The effect of nutritional management of the dairy cow on reproductive efficiency

Early Gestational Hepatic Lipidomic Profiles Are Modulated by One-Carbon Metabolite Supplementation and Nutrient Restriction in Beef Heifers and Fetuses

Background: Maternal nutrition during early gestation induces metabolic adaptations that support maternal health and fetal development. This study evaluated the effects of maternal one-carbon metabolite (OCM: methionine, choline, folate, and vitamin B12) supplementation and restricted rates of maternal gain on the hepatic lipid profiles of dams and fetuses at day 63 of gestation. Methods: Thirty-one crossbred Angus heifers were inseminated and assigned to a 2 × 2 factorial design with two factors: maternal dietary intake (control [CON]; 0.60 kg/day average daily gain [ADG] vs. restricted [RES]; -0.23 kg/day ADG) and OCM supplementation (supplemented [+OCM] vs. not supplemented [-OCM]). The four resulting groups (CON - OCM, CON + OCM, RES - OCM, RES + OCM) were maintained for 63 days post-breeding. Maternal and fetal liver samples were collected, and lipidomic profiling was performed using ultra-performance liquid chromatography-tandem mass-spectrometry. Results: In maternal liver, 485 lipid metabolites were detected, with 243 differing significantly in maternal gain. RES heifers showed increased levels (p ≤ 0.05) of acylcarnitines, plasmalogens, lysoplasmalogens, glycosphingolipids, and sphingomyelins. Additionally, RES combined with OCM supplementation led to the accumulation of secondary bile acids and a depletion of monoacylglycerols (p ≤ 0.05) in maternal liver. In fetal liver, 487 lipid metabolites were detected, but treatment effects were minimal. Conclusions: Maternal rate of gain significantly influenced hepatic lipid metabolism in the maternal liver, while fetal liver lipid profiles remained relatively unaffected. These findings underscore the significant role of dietary intake/rate of gain compared with OCM supplementation in modulating hepatic lipid metabolism and highlight the maternal liver's metabolic adaptations during early pregnancy.

Influence of the intrauterine application of a phytotherapeutic agent and other parameters on the uterine involution of sows in a free farrowing system

Endometritis and postpartum dysgalactiae syndrome are common postpartum disorders in sows revealing antimicrobial treatment. This study evaluated the influence of the intrauterine application of a phytotherapeutic agent (EucaComp©) after farrowing containing essences of marjoram, marigold, melissa and eucalyptus and other sow-related parameters on the uterine involution. In total, 150 Landrace x Large white sows (parity 1-9) were divided randomly into three groups (no intervention (Control), 300 ml sodium chloride (Placebo) and 300 ml of phytotherapeutic agent (Phytotherapeutic)). Several sow-related parameters were assessed such as, parity, Body Condition Score (1-5), birth induction (Yes/No), and feed intake. On days 2, 3, 5, 7 and 21 postpartum, uterine involution was assessed by measuring the diameter on three locations of the uterine horns using ultrasound. The mean uterine diameter changed from 36.4 ± 6.5 mm on day 2-20.4 ± 5.9 mm on day 7 (reduction of 43.81 %) and 14.0 ± 3.2 mm on day 21 (reduction of 61.15 %). No significant differences between the groups and the regression of uterine involution were detected. However, birth induction had a positive effect on uterine involution, increasing the relative uterine involution by 8 %, whereas lack of appetite postpartum, lead to a decrease of 7 % until day 7. An suboptimal BCS (≤2; ≥4) and a parity ≥2 lead to a reduction of uterine involution regression on day 21 by 7 and 5 %. In conclusion, a single postpartal intrauterine application of a phytotherapeutic agent demonstrated no significant impact on uterine involution, while sow-specific and management factors remained pivotal.

Associations between milk infrared-predicted plasma biomarkers of stress resilience and fertility in dairy cattle: Insights for enhancing breeding programs and herd management

Fertility is a crucial aspect of dairy herd efficiency and sustainability. Among factors influencing fertility in dairy cattle, metabolic stress and systemic inflammation of animals are of main relevance, especially in the postpartum stage when ovarian activity begins and cows are inseminated. Our study aimed to infer the associations between milk infrared-predicted blood biomarkers of stress resilience and fertility traits, namely the interval from calving to first service (iCF), days open (DO), and the pregnancy rate at first service (PRF) in a multibreed population of 89,097 dairy cows. The blood metabolites (15 blood biomarkers related to hepatic damage and function, oxidative stress, inflammation, and innate immunity) were predicted using milk Fourier-transform mid-infrared (MIR) spectroscopy. A gradient boosting machine approach with leave-one-batch-out cross-validation (R2 range from 0.45 to 0.82) was implemented to an independent calibration database of 1,367 lactating cows reared in 5 herds. Calibration equations were then applied to a population database of 1,799,186 MIR milk spectral data, that were then merged with fertility data collected by the Breeders Federation of Alto Adige (Bolzano province, Italy) generating a final database of 285,145 records. The 2 databases were merged according to the milk test day (and thus, the MIR spectrum) closest to the date of insemination. The interval fertility traits were fitted as the hazard of either receiving the first service after calving at time t for iCF or becoming pregnant after calving at time t for DO in a Cox proportional-hazards model. Statistical analyses were performed including in the model the number of lactations, year of calving, and herd as fixed effects. The independent effect of the MIR-based predictions of metabolites was also included with each metabolite evaluated separately and discretized into 7 levels based on percentiles. Pregnancy rate at first service, however, was analyzed using logistic regression and the same explanatory variables. The metabolites linked to liver function and damage, such as aspartate aminotransferase, total bilirubin, and alkaline phosphatase, had a relevant influence on iCF and DO in terms of the hazard ratio (HR). Relevant results were also obtained for the biomarkers related to oxidative stress, inflammation, and innate immunity. Specifically, increasing levels of ceruloplasmin, total reactive oxygen metabolites, and advanced oxidation protein products resulted in a relevant decrease in the HR of cows becoming pregnant. The logistic regression analysis did not reveal any significant effect of the aforementioned biomarkers on PRF, indicating that the effects of the stress response mainly concern the resumption of the ovarian cycle after calving. The results for the associations of the predicted biomarkers of the stress response with iCF and DO were consistent with expected physiological patterns. In conclusion, the predicted biomarkers investigated revealed to be promising novel phenotypes for assessing animal health and welfare, in the view of enhancing fertility in dairy cattle also through selective breeding, thus improving the overall efficiency of dairy herds.

The Relationship of Th1/Th2 Cytokine Polarization at Parturition in Cows and SOCS3 Level With Some Postpartum Diseases

Th1/Th2 polarisation and suppressor of cytokine signalling-3 (SOCS3) are important indicators of the humoral and cellular immune system activity in cows. The aim of this study was to determine the correlation of postpartum diseases with the levels of Th1/Th2 polarisation and SOCS3 at the time of parturition. The study examined 180 cows (90 with normal parturition [NP] and 90 with dystocia [D]). Blood samples were taken from the cows once at the time of calving. Two subgroups were created among cows with NP: those without the postpartum disease (NP [-], n = 45) and those with postpartum disease (NP [+], n = 45). Likewise, two subgroups were created among D cows: those without postpartum disease (D [-], n = 45) and those with postpartum disease (D [+], n = 45). Cytokine analyses were performed using species-specific commercial ELISA kits. In the NP (-) group, it was found that Th1/Th2 cytokine polarisation was in the Th1 direction due to the increase in the concentration of IFN-γ, TNF-α and IL-2 in four subgroups grouping with different types of parturition and diseases. It was concluded that it would be appropriate to strengthen cellular immunity. In cases of postpartum diseases, Th1/Th2 polarisation shifted towards Th2 due to the increase in IL-4 and IL-5 concentrations in cows that performed NP and developed mastitis in the postpartum period. These results suggest that it would be beneficial to support the Th2 aspect (i.e. humoral immunity) in cows that have undergone NP and develop mastitis in the postpartum period.

Genotype-by-environment interactions in beef and dairy cattle populations: A review of methodologies and perspectives on research and applications

Modern livestock production systems are characterized by a greater focus on intensification, involving managing larger numbers of animals to achieve higher productive efficiency and animal health and welfare within herds. Therefore, animal breeding programs need to be strategically designed to select animals that can effectively enhance production performance and animal welfare across a range of environmental conditions. Thus, this review summarizes the main methodologies used for assessing the levels of genotype-by-environment interaction (G × E) in cattle populations. In addition, we explored the importance of integrating genomic and phenotypic information to quantify and account for G × E in breeding programs. An overview of the structure of cattle breeding programs is provided to give insights into the potential outcomes and challenges faced when considering G × E to optimize genetic gains in breeding programs. The role of nutrigenomics and its impact on gene expression related to metabolism in cattle are also discussed, along with an examination of current research findings and their potential implications for future research and practical applications. Out of the 116 studies examined, 60 and 56 focused on beef and dairy cattle, respectively. A total of 83.62% of these studies reported genetic correlations across environmental gradients below 0.80, indicating the presence of G × E. For beef cattle, 69.33%, 24%, 2.67%, 2.67%, and 1.33% of the studies evaluated growth, reproduction, carcass and meat quality, survival, and feed efficiency traits, respectively. By contrast, G × E research in dairy cattle populations predominantly focused on milk yield and milk composition (79.36% of the studies), followed by reproduction and fertility (19.05%), and survival (1.59%) traits. The importance of G × E becomes particularly evident when considering complex traits such as heat tolerance, disease resistance, reproductive performance, and feed efficiency, as highlighted in this review. Genomic models provide a valuable avenue for studying these traits in greater depth, allowing for the identification of candidate genes and metabolic pathways associated with animal fitness, adaptation, and environmental efficiency. Nutrigenetics and nutrigenomics are emerging fields that require extensive investigation to maximize our understanding of gene-nutrient interactions. By studying various transcription factors, we can potentially improve animal metabolism, improving performance, health, and quality of products such as meat and milk.

Severe body condition loss lowers hepatic output of IGF1 with adverse effects on the dominant follicle in dairy cows

The severe loss of body condition score (BCS) during the early lactation period has been associated with infertility in cows. However, the mechanisms are not fully understood. The aim of this study was to examine the effect of BCS loss on liver health, and ovarian functions in cows during early lactation. Retrospectively multiparous cows from two farms were categorized based on units of BCS (1-5 scale) loss as Moderate (MOD, <0.75 units; n = 11) or Severe (SEV, ≥0.75 units; n = 9) loss groups. From Weeks -3 to 7, relative to calving, MOD and SEV cows lost on average 0.4 and 1.0-unit BCS, respectively. All data except hepatic transcriptomes were analyzed with PROC MIXED procedure of SAS. The plasma concentration of non-esterified fatty acids at Week 0 and 1, ß-hydroxy butyrate at Week 1, and γ-glutamyl transferase at Weeks 1 and 7 relative to calving were higher in SEV cows. Hepatic transcriptome analysis showed that 1 186 genes were differentially expressed in SEV (n = 3) compared to MOD (n = 3) cows at Week 7 after calving. Pathway analysis revealed that significant DEGs in SEV cows enriched in lipid metabolisms including, lipid metabolic process, ether lipid metabolism, fatty acid beta-oxidation, fatty acid biosynthetic process, fatty acid metabolic process, fat digestion and absorption, linoleic acid metabolism, alpha-linolenic acid metabolism. The impaired liver function in SEV cows was associated with 1.5-fold reduction of hepatic IGF1 gene expression and lower serum IGF1 concentrations. At the ovarian level, SEV cows had lower IGF1 concentration in the follicular fluid of the dominant follicle of the synchronized follicular wave compared to that of MOD cows at 7 weeks after calving. Further, the follicular fluid concentration of estradiol-17β was lower in SEV cows along with lower transcript abundance of genes from granulosa cells associated with dominant follicle competence, including CYP19A1, NR5A2, IGF1, and LHCGR. These data show that SEV loss of BCS during early lactation leading up to the planned start of breeding is associated with liver dysfunction, including lower IGF1 secretion, and impaired function of the dominant follicle in the ovary.

Genetic diversity and positive signatures of selection in indigenous cattle breeds of Iran

Animal domestication, climate changes over time, and artificial selection have played significant roles in shaping the genome structure of various animal species, including cattle. These processes have led to the emergence of several indigenous cattle breeds with distinct genetic characteristics. This study focused on unraveling the genetic diversity and identifying candidate genomic regions in eight indigenous cattle breeds of Iran. The data consisted of ∼777 962 single nucleotide polymorphisms (SNPs) of 89 animals from Iranian indigenous cattle scattered throughout the country. We employed various methods, including integrated haplotype score, FST, and cross-population composite likelihood ratio, to conduct a genome scan for detecting selection signals within and between cattle populations. Average observed heterozygosity across the populations was 0.36, with a range of 0.32-0.40. In addition, negative and low rates of inbreeding (FIS) in the populations were observed. The genome-wide analysis revealed several genomic regions that harbored candidate genes associated with production traits (e.g., MFSD1, TYW5, ADRB2, BLK, and CRTC3), adaptation to local environmental constraints (CACNA2D1, CXCL3, and GRO1), and coat color (DYM). Finally, the study of the reported quantitative trait loci (QTL) regions in the cattle genome demonstrated that the identified regions were associated with QTL related to important traits such as milk composition, body weight, daily gain, feed conversion, and residual feed intake. Overall, this study contributes to a better understanding of the genetic diversity and potential candidate genes underlying important traits in Iranian indigenous cattle breeds, which can inform future breeding and conservation efforts.

Biomarkers of oxidative stress and liver function in early lactation and their relationship with the reproductive efficiency of multiparous grazing dairy cows in Argentina. A retrospective study

This study aimed to analyze the possible relationship between days to conception and different oxidative stress (OS) biomarkers and liver functional parameters in multiparous dairy cows. Besides, a fast reliable method for the accurate measurement of malondialdehyde (MDA) by liquid chromatography-tandem mass spectrometry was developed in several matrices. During lactation, the days to conception of 28 cows were determined for a retrospective study. According to this parameter, cows were divided into two groups: high and low days to conception (HDC and LDC, respectively). Blood, urine and liver biopsies were sampled 21 days before the expected calving date, and 7 and 21 days after calving. The method developed for MDA was validated according to international requirements. The lower limit of quantification was 0.25 µmol/L for plasma and urine and 10.00 µmol/L for liver tissue. No differences between groups were observed in the systemic concentration of non-esterified fatty acids, β-hydroxybutyric acid and liver triacylglycerol content (P > 0.05). Cholesterol concentration was higher in the LDC than in the HDC group (P < 0.05). Plasma 3-nitrotyrosine (3-NT) concentration was lower in the LDC than in the HDC group on day 21 post-calving (P < 0.05). Superoxide dismutase activity was higher in the LDC than in the HDC group (P < 0.05). Particularly, in the liver, 3-NT and MDA concentrations were lower in the LDC than in the HDC group (P < 0.05). These results allow inferring that the amelioration of OS biomarkers in plasma and liver could be related to a better reproductive performance of dairy cows.

Precision technologies for the management of reproduction in dairy cows

Precision livestock farming (PLF) utilizes information and communication technology (ICT) to continuously monitor, control, and enhance the productivity, reproduction, health, welfare, and environmental impact of livestock. Technological advancements have facilitated the seamless flow of information from animals to humans, enabling practical decision-making processes concerning health, reproduction management, and calving surveillance. With the increasing population of livestock per farm, it has become impractical for farmers to individually track every animal within these large groups. Historically, cattle management decisions heavily relied on human observation, judgment, and experience. However, it is impossible for a single individual to gather reliable audio-visual monitoring data round the clock. Presently, dairy cows exhibit subtler indicators of estrus, resulting in a substantial chance of missing an estrus cycle. Furthermore, calving complications sometimes go unnoticed on farms, resulting in a higher number of culled cattle. In addition, an increasing number of crossbred cows experience delayed return to estrus after calving due to low body condition scores (BCS). The decline in BCS during the dry period is associated with a reduced likelihood of pregnancy following the first and second postpartum inseminations. Precision technologies enable the monitoring and tracking of an individual cow's physiological behavior and reproductive parameters, thereby optimizing management practices and farm performance. Despite the exploration of various technologies, there are still some common challenges that need to be addressed, including battery lifespan, transmission range, specificity and sensitivity, storage capacity, and economic affordability. Nonetheless, the demand for these tools from farmers and researchers is growing, and the implementation of PLF in grazing systems can yield positive outcomes in terms of animal reproductive welfare and labor optimization. This review primarily focuses on the different aspects of reproduction management in dairy using sensors, automated cameras, and various computer software.

[Influence of an eCG administration on puerperal involution and fertility in Simmentaler cows]

SUBJECT AND AIM

In the literature, various methods aiming for a promotion of uterine involution and ovarian function in post-partum dairy cattle have been described. Recently, successful use of equine choriongonadotropin (eCG) in this context has been repeatedly reported, while other studies have failed to demonstrate positive effects of eCG administration on puerperal involution in cows. Due to the contradictory results described in the literature, the aim of this field study was to verify whether the administration of eCG on day 10 post-partum exerts a positive effect on uterine involution, ovarian activity and fertility indices in Simmental cows.

MATERIAL AND METHODS

In nine dairy farms, 205 Simmental cows were divided by lot into three groups: Group 1 animals received 500 I.U. eCG, group 2 received 50 µg gonadorelin, and group 3 animals received 250 mg butafosfan and 125 µg cyanocobalamin (control group). Treatment was administered on day 10 post-partum in each case. The animals were examined clinically and ultrasonographically on the 10th, 25th and 42nd day post-partum and the time to insemination and pregnancy were recorded. Group comparison with respect to the recorded parameters was initially performed without considering confounding factors by analysis of variance. In the second step, potential influencing variables (lactation, milk yield, change in backfat thickness, retentio secundarium and serverity of the obstetric intervention) were taken into account, as well as the combination of the random factors "farm" and "individual animal within the farm".

RESULTS

The administration of eCG exhibited no significant effect on uterine involution, however, the cervical involution was influenced significantly. In the group of cows with eCG treatment, ovarian cysts were detected significantly more frequently on day 25 post-partum (p=0.04). This difference did not persist on the 42nd day post-partum. Neither voluntary waiting period nor the days open were significantly shortened by eCG administration. Lactation number showed a significant effect on uterine involution. Heifers exhibited more rapid involution by day 42 post-partum than cows.

CONCLUSION

Administration of eCG in Simmentaler cows at day 10 post-partum showed no positive effect.

CLINICAL RELEVANCE

The use of eCG in early puerperium to promote fertility in the cow should be avoided.

Prepartum Magnesium Butyrate Supplementation of Dairy Cows Improves Colostrum Yield, Calving Ease, Fertility, Early Lactation Performance and Neonatal Vitality

Butyrate promotes rumen epithelium growth and function; however, the effect of prepartum butyrate supplementation on dairy cow productivity, health and their offspring has not been extensively studied. Furthermore, no studies have investigated the effect of magnesium butyrate (MgB), which is also a source of magnesium. A trial was performed to test the hypothesis that prepartum MgB supplementation (105 g/cow/day) would increase colostrum quality and improve calving, newborn calf vitality and cow health. Multiparous Holstein cows were randomly assigned to MgB supplemented (n = 107) and Control groups (n = 112). Colostrum yield and the total yield of IgG, protein and lactose were higher (p ≤ 0.05) in the supplemented group. The calving assistance rate was lower (p ≤ 0.012), and the neonatal vitality score was higher (p ≤ 0.001) in the MgB group. Improved parameters related to cow health and fertility were observed in the supplemented group. The MgB group also had higher milk yield during the first week of lactation (p ≤ 0.001), and a higher (p ≤ 0.05) body condition score from 3 to 9 weeks after calving. In conclusion, prepartum MgB supplementation provides a wide range of benefits for dairy cows, as well as their newborn calves.

Transvaginal ultrasound-guided oocyte retrieval in cattle: State-of-the-art and its impact on the in vitro fertilization embryo production outcome

Transvaginal ultrasound-guided oocyte retrieval (commonly called OPU) and in vitro embryo production (IVP) in cattle has shown significant progress in recent years, in part, as a result of a better understanding of the full potential of these tools by end users. The combination of OPU and IVP (OPU-IVP) has been successfully and widely commercially used worldwide. The main advantages are a greater number of embryos and pregnancies per unit of time, faster genetic progress due to donor quick turn around and more elite sires mating combinations, larger spectrum of female age (calves, prepuberal, heifer, cow) and condition (open, pregnant) from which to retrieve oocytes, a reduced number of sperm (even sexed) required to fertilize the oocytes, among other benefits. OPU-IVP requires significant less donor preparation in comparison to conventional embryo transfer (<50% of usual FSH injections needed) to the extent of no stimulating hormones (FSH) are necessary. Donor synchronization, stimulation, OPU technique, oocyte competence, embryo performance, and its impact on cryopreservation and pregnancy are discussed.

Contribution of key elements of nutritional metabolism to the development of cystic ovarian disease in dairy cattle

The alteration of signaling molecules involved in the general metabolism of animals can negatively influence reproduction. In dairy cattle, the development of follicular cysts and the subsequent appearance of ovarian cystic disease (COD) often lead to decreased reproductive efficiency in the herd. The objective of this review is to summarize the contribution of relevant metabolic and nutritional sensors to the development of COD in dairy cows. In particular, we focus on the study of alterations of the insulin signaling pathway, adiponectin, and other sensors and metabolites relevant to ovarian functionality, which may be related to the development of follicular persistence and follicular formation of cysts in dairy cattle. The results of these studies support the hypothesis that systemic factors could alter the local scenario in the follicle, generating an adverse microenvironment for the resumption of ovarian activity and possibly leading to the persistence of follicles and to the development and recurrence of COD.

Associations of automated body condition scores at dry-off and through early lactation with milk yield of Holstein cows

The objective of this study was to analyze the associations of body condition score (BCS) and BCS change (∆BCS) during the dry period and the first 100 d of lactation with daily milk yield. Examining the involvement of health status in the associations between BCS and milk yield was a secondary objective of this research. Data included 12,042 lactations in 7,626 Holstein cows calving between April 2019 and January 2022 in a commercial dairy operation located in Colorado, USA. BCSs were generated daily by an automated BCS camera system located at the exit of the milking parlor. The assessment points selected for this study were dry-off (BCSdry), calving (BCS1), 7 DIM (BCS7), 14 DIM (BCS14), 21 DIM (BCS21), and nadir (nBCS; defined as the lowest daily BCS from calving to 100 DIM). Subsequently, these BCS were categorized considering quartiles (Q1 = 25% lowest BCS; Q4 = 25% greatest BCS), separately for primiparous and multiparous cows. Changes in BCS were calculated from dry-off to calving (multiparous); and from calving to 7 DIM, 14 DIM, 21 DIM, and nadir and assigned into quartile categories considering Q1 as the 25% of cows with the greatest decrease of BCS. Lactations were classified based on the number of health events before nadir as healthy, affected by one event, or having multiple events. Data were examined in primiparous and multiparous cows separately using ANOVA. The least square means for daily milk at 60 DIM and 305 DIM were calculated by category of BCS and ∆BCS at multiple time points and time periods. Subsequently, lactation curves were created by BCS and ∆BCS categories and by health status. Multivariable models included calving season and BCS1 as covariables. The largest differences in milk yield among categories of BCS and ∆BCS were identified for BCS originated at nadir and for the ∆BCS between calving and nadir. The differences in average daily milk yield between cows in the lowest and the greatest nBCS category (Q1 vs. Q4) were 3.3 kg/d (60 DIM) and 3.4 kg/d (305 DIM) for primiparous cows and 2.4 kg/d (60 DIM) and 2.1 kg/d (305 DIM) for multiparous cows. During the period from calving to nadir, primiparous cows in Q1 (greatest decrease of BCS) produced 4.3 kg/d (60 DIM) and 3.8 kg/d (305 DIM) more than cows in Q4. For multiparous cows, the differences were 3.0 kg/d (60 DIM) and 1.9 kg/d (305 DIM) in favor of Q1 cows. Overall, the associations between BCS and ∆BCS categories and milk yield were not consistent across time and they depended on the parity category. Nonetheless, as the assessment of BCS and ∆BCS approached the nadir, the association between greater milk yield and lower BCS or greater reduction in BCS became more evident.

Mastitis: What It Is, Current Diagnostics, and the Potential of Metabolomics to Identify New Predictive Biomarkers

Periparturient diseases continue to be the greatest challenge to both farmers and dairy cows. They are associated with a decrease in productivity, lower profitability, and a negative impact on cows’ health as well as public health. This review article discusses the pathophysiology and diagnostic opportunities of mastitis, the most common disease of dairy cows. To better understand the disease, we dive deep into the causative agents, traditional paradigms, and the use of new technologies for diagnosis, treatment, and prevention of mastitis. This paper takes a systems biology approach by highlighting the relationship of mastitis with other diseases and introduces the use of omics sciences, specifically metabolomics and its analytical techniques. Concluding, this review is backed up by multiple studies that show how earlier identification of mastitis through predictive biomarkers can benefit the dairy industry and improve the overall animal health.

Changes in body condition score from calving to first insemination and milk yield, pregnancy per AI, and pregnancy loss in lactating dairy cows: A meta-analysis

We determined the association of body condition score (BCS) at calving, at first postpartum artificial insemination (AI), and change in BCS between calving and first AI on pregnancy per AI (P/AI) at 30-45 d, pregnancy loss to 60-85 d, and milk yield in lactating dairy cows. Outcome data were included from 15 studies and 47 herd-year combinations. Additional variables included season of AI, herd, days in milk at first AI, parity, and of mean daily milk yield within 2 wk of first AI. The BCS scale employed was a standard 1-5 scale (1 = severe under conditioning or emaciated and 5 = severe over conditioning) with 0.25 cut points. Presynchronization treatments that included PGF_2α and GnRH increased (P < 0.05) the proportion of cows with luteal function before AI compared with PGF_2α alone. Compared with no presynchronization treatment those that included PGF_2α or PGF_2α and GnRH increased (P < 0.05) first P/AI. Cows having BCS ≥2.75 at AI had greater (P < 0.01) first P/AI than cows with BCS <2.75. As BCS at first AI increased, P/AI increased in a linear (P = 0.04) fashion and was greater in cows expressing estrus when BCS at AI was <2.50. Presynchronization had no association with P/AI for cows with BCS at calving <3.00 compared with those with BCS ≥3.00. In contrast, multiparous cows tended (P = 0.06) to have greater P/AI when they calved with BCS ≥3.00 compared with <3.00. Increasing BCS at AI was associated with decreased (P = 0.01) pregnancy loss. Pregnancy per AI did not differ among cows according to the magnitude of prebreeding BCS loss, but more multiparous cows losing more than 0.5 units of BCS tended to have greater pregnancy losses in second-parity cows (P = 0.09) and in cows of third or greater (P < 0.001) parity. Daily milk yields at first AI differed among parities as expected, but a parity by BCS at calving interaction was detected (P = 0.008). Daily milk yield at first AI decreased (P < 0.001) linearly as BCS at AI increased, with an exacerbated greater negative effect during summer. More prebreeding loss in BCS was associated with more (P < 0.05) milk yield in first- and second-parity cows. We concluded that greater BCS at first AI was associated with improved P/AI, but magnitude of prebreeding BCS loss was not associated with P/AI. In contrast, more pregnancy loss was associated with more prebreeding BCS loss in multiparous cows. Cow having lesser BCS at AI and greater prebreeding loss in BCS produced more milk than their herd mates of greater BCS and lesser prebreeding loss in BCS, respectively.

Metabolic exchanges between the oocyte and its environment: focus on lipids

Finely regulated fatty acid (FA) metabolism within ovarian follicles is crucial to follicular development and influences the quality of the enclosed oocyte, which relies on the surrounding intra-follicular environment for its growth and maturation. A growing number of studies have examined the association between the lipid composition of follicular compartments and oocyte quality. In this review, we focus on lipids, their possible exchanges between compartments within the ovarian follicle and their involvement in different pathways during oocyte final growth and maturation. Lipidomics provides a detailed snapshot of the global lipid profiles and identified lipids, clearly discriminating the cells or fluid from follicles at distinct physiological stages. Follicular fluid appears as a main mediator of lipid exchanges between follicular somatic cells and the oocyte, through vesicle-mediated and non-vesicular transport of esterified and free FA. A variety of expression data allowed the identification of common and cell-type-specific actors of lipid metabolism in theca cells, granulosa cells, cumulus cells and oocytes, including key regulators of FA uptake, FA transport, lipid transformation, lipoprotein synthesis and protein palmitoylation. They act in harmony to accompany follicular development, and maintain intra-follicular homeostasis to allow the oocyte to accumulate energy and membrane lipids for subsequent meiotic divisions and first embryo cleavages.

A Longitudinal Study of Cattle Productivity in Intensive Dairy Farms in Central Ethiopia

Ethiopia is witnessing an emergence of intensive urban dairy farming. The aims of this study were to capture cattle productivity parameters in selected intensive dairy farms in and around Addis Ababa (Central Ethiopia). The study is a pre-requisite and baseline for further economic analysis of diseases such as bovine tuberculosis (BTB) and to assess some of the current challenges faced by farm owners for optimal animal performances. Hence, a 3-year longitudinal observational study was conducted for the first time in Ethiopia, in 24 dairy farms with intensive husbandry, including a total of 1,705 dairy animals. Herd characteristics, animal movement, and productivity parameters (fertility, morbidity, mortality) were recorded in a herd-book. Whereas, half the farms saw their animals increase in number over the 3 years, 37.5% (mainly large farms) saw their herd size decrease. Offtakes accounted for 76.6% of all animal exits. One hundred and ninety (11.1%) animals died of natural causes. Highest mortality was observed in young stock (13.9%). Overall, diseases were the leading cause for death (57.5%). The majority of calves (69%) that died, did so within the first week of life. Mean calving interval (CI) was 483.2 days. Successful conception after artificial insemination (AI) was 66.1% with Addis Ababa and smaller farms faring worst. Mean time interval from calving to first service was 152 days. Date of birth to first service was 592.2 days and date of birth to first calving was 794.7 days. In conclusion, the study showed sub-optimal productivity performances in intensive dairy cattle and highlighted some of the current gaps and challenges in urban dairy productivity.

Body status and blood metabolites profiles during resumption of postpartum ovarian activity in yak (Poephagus grunniens)

We examined the changes in body weight (BW), back-fat thickness (BFT) and blood metabolites in relation to postpartum (PP) ovarian activity status in twenty female yaks raised under semi-intensive system. BFT and ovarian activities, like follicle development, ovulation (OV) and corpus luteum (CL) development, were monitored from 4 to 15 weeks (wk) PP using ultrasonography. Resumption of ovarian activity was confirmed with ovulation of dominant follicle (DF) and subsequent CL development, and >1 ng/ml progesterone concentration in blood plasma sample after 1week of ovulation. Yaks were further classified as cyclic (with CL), acyclic (without CL), and cystic (with >25 mm follicular cyst; FC). Within 20 weeks PP, 60% yaks resumed cyclic ovarian activity, while 25% failed to initiate cycling activity, and 15% developed follicular cysts. In all categories of yak, BW gradually decreased (p < .05) till nadir; however, nadir reached earlier (p < .05) in acyclic yaks. BFT differed (p < .05) among the yak groups, but it tended to be higher in cyclic yaks as compared to acyclic and cystic. No difference (p > .05) in non-esterified fatty acids (NEFA) values was found among the different categories of yaks, whereas, beta-hydroxy butyrate (BHB) levels were higher in cystic animals as compared to acyclic and cyclic. Blood glucose levels decreased in all yaks during initial 2 weeks after calving. Our findings suggest that yaks with low BW, BFT and glucose levels, and higher BHB values were at risk of delayed resumption of ovarian activity and concomitant development of follicular cysts.

Unintended consequences of selection for increased production on the health and welfare of livestock

Modern farming technologies, including quantitative selection and breeding methods in farm animal species, resulted in increased production and efficiency. Selection for increased output in both intensive and extensive production systems has trade-offs and negative outcomes, often more pronounced in intensive systems. Animal welfare and health are often adversely affected and this influences sustainable production. The relative importance of animal welfare differs among developed and developing countries due to the level of economic development, food security and education, as well as religious and cultural practices which presents challenges for sound scientific research. Due to breeding goals in the past set on growth performance, traits such as fertility, welfare and health have been neglected. Fertility is the single most important trait in all livestock species. Reduced fertility and lameness, claw health and mastitis results in unnecessary culling and reduced longevity. Selection pressure for growth accompanied with inbreeding has resulted in a number of genetic defects in beef, sheep and pigs. This review demonstrated the importance of inclusion of animal welfare concepts into breeding objectives and selection strategies. Accurate phenotyping of welfare traits is a limiting factor in the implementation of mitigating strategies, which include diagnostic testing, control of inbreeding and genomic selection.

The effects of glutathione ethyl ester in in vitro maturation on the developmental ability of oocytes derived from cattle with liver abnormalities

The main objectives of this study was to identify the effects of a relationship of hyper-concentration of Gamma-glutamyltransferase (γ-GTP) in follicle fluid (FF) on the levels of glutathione (GSH)/reactive oxygen species (ROS) in oocytes and subsequent embryo development in cattle with abnormal livers. Furthermore, we investigated the effect of supplementing in vitro maturation medium with glutathione ethyl ester (GSH-OEt) on the subsequent developmental potential of oocytes from such cattle. We used a control group of cattle (with normal livers) and a liver disorder (LD) group, in which the liver was diagnosed as being abnormal. In experiment 1, the LD group was divided to two subgroups according to the concentration of γ-GTP in FF: a low group (≤50 IU/L; the low LD group), and a high group (>50 IU/L: the high LD group). Cumulus oocyte-complexes (COCs) were matured and fertilized in vitro and then cultured to the blastocyst stage. The levels of GSH and ROS in the matured oocytes after IVM were then assessed in each group. On day 7 after fertilization, embryo cleavage and development were assessed. We found that the rate of development to the blastocyst stage was significantly lower in the high LD group than in the control group and the low LD group. The levels of GSH in matured oocytes were significantly lower in the high LD group than in the control group and low LD group. The levels of ROS in matured oocytes was significantly higher in the high LD group than in the control group and the low LD group. In experiment 2, COCs from cattle in the high LD group were matured in m-199 supplemented with 5 mM GSH-OEt, then IVF and IVC was performed for 7 days. The GSH levels were determined in some COCs after IVM. The supplementation of media with GSH-OEt during IVM increased the levels of GSH in mature oocytes and improved the rate of blastocyst development compared with the control group. In conclusion, GSH-OEt supplementation to media during IVM can improve the developmental potential of oocytes in liver-diseased cattle with high γ-GTP concentrations in the FF by increasing intracellular GSH synthesis and scavenging ROS.

Patterns of blood biochemical parameters of peripartum dairy cows raised in either smallholder or semi-commercial dairy farms in Thailand

Background and Aim:

Data about dynamics of serum biochemical parameters and negative energy balance (NEB) related conditions differ among geographical areas or farm types. It should be cautious about applying those data to justify control and prevention strategies of NEB problems. Therefore, dynamics of blood biochemical parameters related to NEB condition of peripartum dairy cows raised in either smallholder (SH) or semi-commercial (SC) farms were studied.

Materials and Methods:

Thirty-two healthy pregnant dry cows were selected from five dairy farms in Western part of Thailand, including 15 and 17 cows from three SH and two SC farms, respectively. Blood samples were collected at 2 weeks before the expected calving date, and 1, 2, 4, and 8 weeks postpartum to determine concentrations of glucose, non-esterified fatty acid (NEFA), and b-hydroxybutyrate (BHBA). Body condition scores (BCSs) and milk yields were also recorded.

Results:

Dairy cows in both farm types suffered from NEB by elevation of serum NEFA and BHBA, and loss of BCS postpartum. Degrees of elevation in serum NEFA and BHBA were different between farm types. The SC cows showed more BCS loss postpartum, but lower serum NEFA. In the SH cows, even with less BCS loss, the cows showed high serum NEFA concentrations.

Conclusion:

Dairy cows in our study entered NEB condition even with low milk yields. Moreover, elevation of serum NEFA and BHBA postpartum was higher in our studied cows as compared with other studies in high producing cows of commercial dairy farms in temperate areas.

Postpartum Uterine Involution and Embryonic Development Pattern in Chinese Holstein Dairy Cows

Understanding the postpartum uterine involution pattern and embryonic development could facilitate bovine reproduction management, improve reproductive efficiency, and diagnosis of the reproductive disorder, which would contribute to the success of the dairy business. This study aimed to investigate postpartum uterine involution and embryonic developmental patterns or postconceptional marks of embryonic fetal development in Chinese Holstein dairy cows using B-mode ultrasonography. The results revealed a significant decline in the involution period with an increase of parity and age. The uterine involution period was shorter in multiparous cows when compared with cows with lower parities. Consistently, cows over 4 years old recovered faster than younger cows (2 or 3 years). Besides, the elder cows (over 4 years) had a relatively larger size of resumed cervix uteri and horns. Postpartum uterine involution pattern analysis revealed that the reproductive tract recovered very fast during the first 16 days postpartum for all the parity. Results of postconceptional marks of embryo development revealed a slow increase in diameter of the gravid uterine horn and crown-rump length (CRL) before day 60. In contrast, this increase was dramatic and rapid after the 60th day. We also established two models to estimate gestational age based on gravid uterine horn diameter or CRL. A formula was established to determine the gravid uterine horn size during postconceptional on day 30th–day 90th (r = 0.8714, P < 0.01). In addition, a significant positive correlation between CRL and gestational age (r = 0.98151, P < 0.01) was built. In conclusion, these results illustrated that parity and calving age had significant effects on uterine involution in Chinese Holstein cows. Crown-rump length and gravid uterine horn diameter are both efficient for evaluating the embryo growth. These current findings broaden the understanding of basic reproductive pattern in Chinese Holstein cows and could benefit bovine reproductive management primarily in postpartum and early pregnant cows to reduce the calving interval and avoid periparturient metabolic diseases.

Effects of herd fertility on the economics of sexed semen in a high-producing, pasture-based dairy production system

This study used a stochastic simulation model to estimate the potential economic benefit of using sexed semen in heifers only and in heifers and lactating cows in a high-producing, pasture-based system under 3 fertility scenarios. Three breeding strategies were modeled: (1) only heifers inseminated with sexed semen and cows inseminated with conventional unsexed semen (SSH); (2) both heifers and cows inseminated with sexed semen (SSHC); and (3) a reference scenario in which all females were inseminated with conventional, unsexed semen (CONV). Each scenario was evaluated under 3 herd fertility states: high (HF), medium (MF), and low (LF), which, under the reference scenario, corresponded to herd replacement rates of 21, 25, and 31%, respectively. The model estimated the economic profit, including the net present value of the genetic gain from selection intensity. The economic return from adoption of sexed semen strategies declined, with reduced levels of baseline herd fertility turning negative in the LF state. The mean (±SD) sexed semen advantage (SSA) per cow for HF-SSH, MF-SSH, and LF-SSH scenarios were €30.61 ± 8.98, €27.45 ± 7.19, and €14.69 ± 11.06, respectively. However, the SSA per cow for HF-SSHC, MF-SSHC, and LF-SSHC scenarios were €49.14 ± 15.43, €18.46 ± 30.08, and -€19.30 ± 57.11. The range in economic profit for SSA for SSH was most sensitive to calf prices in HF-SSH and the pregnancy rate of sexed semen as a percentage of conventional unsorted semen in MF-SSH and LF-SSH. The range in economic profit for SSA for SSHC scenarios was most sensitive to the pregnancy rate of sexed semen as a percentage of conventional unsorted semen in HF-SSHC, MF-SSHC, and LF-SSHC. This study highlights the effect of baseline herd fertility state on the financial advantage of adopting sexed semen in a pasture-based dairy production system.

Mineral profile of abandoned cows suffering from anestrus

The present investigation was carried out with an objective of studying the mineral profile in abandoned cows affected by anestrus (N=83). Overall 83 abandoned cows kept in 18 Goshalas were diagnosed to be affected with anestrus. The macro minerals, i.e. calcium (Ca), magnesium (Mg) and microminerals, viz. copper (Cu), zinc (Zn), cobalt (Co) and manganese (Mn) were estimated from plasma. Nutritional supplementation led to a successful recovery in 42.17% cows. Mineral profile suggested that inorganic phosphorus and copper concentration increased significantly in recovered anestrus cows. All other minerals also witnessed a non-significant increase in recovered as well as nonrecovered cows after treatment. In conclusion, anestrus could be successfully treated to an extent following nutritional supplementation.

Kick-starting ovarian cyclicity by using dietary glucogenic precursors in post-partum dairy cows: a review

The objective of this review is to describe how dietary glucogenic precursors could stimulate ovarian activity in post-partum dairy cows and improve reproductive success. Although the nutrient requirements for the early resumption of ovarian cycles, and for follicle and embryo development are quantitatively small, reproductive success is deteriorated by post-partum negative energy balance. Since very little glucose is absorbed directly from the digestive tract of ruminants one of the targets for nutritional manipulation could be the glucogenic potential of the diet. This could be achieved by giving rumen-resistant starch or mono-propylene glycol. Both these adaptations increase glucose, insulin and insulin-like growth factor-1 plasma concentrations and stimulate ovarian follicle growth.

Effects of a n-3 polyunsaturated fatty acid-enriched diet on embryo production in dairy cows

Beneficial effects of n-3 polyunsaturated fatty acid (PUFA) supplementation on dairy cow reproduction have been previously reported. The objectives of the present study were to assess whether n-3 PUFA supplementation would affect in vitro embryo production (IVP) after ovarian stimulation. Holstein cows received a diet with 1% dry matter supplementation of either n-3 PUFA (n = 18, microencapsulated fish oil) or a control, n-6 PUFA (n = 19, microencapsulated soy oil). Both plasma and follicular fluid FA composition showed integration of total PUFA through the diet. All cows underwent an IVP protocol consisting of ovarian stimulation, ultrasound-guided transvaginal oocyte retrieval (ovum pick-up, OPU, five per cow) followed by in vitro maturation, fertilisation and 7 days of embryo development. A tendency toward an increase in the blastocyst rate (diet effect, P = 0.0865) was observed in n-3 cows, with 49.6 ± 5.5% vs 42.3 ± 5.5% in control n-6 cows. A significant increase (diet effect, P = 0.0217) in the good-quality blastocyst rate (freezable blastocysts) was reported in n-3 cows (42.2 ± 7.7%) compared to control n-6 cows (32.7 ± 7.7%). A significant difference in lipid composition was shown in the oocytes recovered by OPU from n-3 and n-6 treated cows, by intact single-oocyte MALDI-TOF mass spectrometry. The 42 differentially abundant identified lipids were mainly involved in cell membrane structure. In conclusion, n-3 PUFA supplementation enhanced oocyte quality and modified their lipid composition. Further studies are necessary to investigate the potential link of these lipid modifications with enhanced oocyte quality.

Metabolic biomarkers, body condition, uterine inflammation and response to superovulation in lactating Holstein cows

The objective was to determine associations between response to superovulation and body condition, subclinical endometritis and circulating metabolic biomarkers [adiponectin, leptin, insulin, IGF1, tumor necrosis factor (TNF) α, interleukin (IL) 1β, IL6, and urea] in lactating dairy cows. Ten multiparous lactating Holstein cows in each body condition score (1-5; 1 emaciated; 5 obese) category (BCSC) 2.00 to < 2.50 (BCSC1), 2.50 to < 3.00 (BCSC2), 3.00 to <3.50 (BCSC3), 3.50 to <4.00 (BCSC4) and 4.00 to 5.00 (BCSC5) groups (total n = 50) were randomly selected and superovulated, timed artificially inseminated with frozen-thawed semen from three sires and embryos collected (n = 50 collections). At embryo collection, blood samples and embryo recovery fluid were collected for determination of metabolic markers and presence of subclinical endometritis (lavage technique; > 6% PMN). In total, 379 embryos were collected (average of 7.6 embryos per superovulation). Mean numbers of total ova and embryos was greater for cows in BCSC2, BCSC3 and BCSC4 groups compared with cows in BCSC1 and BCSC5 groups (P < 0.01). Total number of transferrable embryos were greater for cows in BCSC 2 and BCSC3 groups compared with cows in BCSC1, BCSC4 and BCSC5 groups (P < 0.01). Mean number of total ova and embryos and of transferrable embryos was higher for cows with 0 or 1-6% PMN compared to cows with >6% PMN (P < 0.01). In addition, there was a quadratic association between blood urea nitrogen concentrations and % transferrable embryos (r² = 0.85; P < 0.05) and between BCS and % transferrable embryos (r² = 0.73; P < 0.05). Circulating adiponectin, leptin, insulin, IGF1 and TNFα were greater in cows with moderate to good body condition compared to thin or obese cows (P < 0.05). Circulating adiponectin, leptin, IGF1 and insulin were greater in normal cows (≤6% PMNs), whereas, TNFα and IL1β and IL6 were greater in cows with subclinical endometritis (P < 0.05). In conclusion, BCS and subclinical endometrial inflammation were associated with superovulatory response and embryo quality. Further, circulating metabolic biomarkers were associated with superovulatory response and embryo quality, likely due to donor's metabolic status and uterine environment. Optimizing superovulatory responses and embryo quality in lactating dairy cows requires management of nutrition and uterine health.

Model-based exploration of the impact of glucose metabolism on the estrous cycle dynamics in dairy cows

BACKGROUND

Nutrition plays a crucial role in regulating reproductive hormones and follicular development in cattle. This is visible particularly during the time of negative energy balance at the onset of milk production after calving. Here, elongated periods of anovulation have been observed, resulting from alterations in luteinizing hormone concentrations, likely caused by lower glucose and insulin concentrations in the blood. The mechanisms that result in a reduced fertility are not completely understood, although a close relationship to the glucose-insulin metabolism is widely supported.

RESULTS

Following this idea, we developed a mathematical model of the hormonal network combining reproductive hormones and hormones that are coupled to the glucose compartments within the body of the cow. The model is built on ordinary differential equations and relies on previously introduced models on the bovine estrous cycle and the glucose-insulin dynamics. Necessary modifications and coupling mechanisms are thoroughly discussed. Depending on the composition and the amount of feed, in particular the glucose content in the dry matter, the model quantifies reproductive hormones and follicular development over time. Simulation results for different nutritional regimes in lactating and non-lactating dairy cows are examined and compared with experimental studies. The simulations describe realistically the effects of nutritional glucose supply on the ovulatory cycle of dairy cattle.

CONCLUSIONS

The mathematical model enables the user to explore the relationship between nutrition and reproduction by running simulations and performing parameter studies. Regarding its applicability, this work is an early attempt towards developing in silico feeding strategies and may eventually help to refine and reduce animal experiments.

REVIEWERS

This article was reviewed by John McNamara and Tin Pang (nominated by Martin Lercher).

Metabolomic Profile of Oviductal Extracellular Vesicles across the Estrous Cycle in Cattle

Oviductal extracellular vesicles (oEVs) have been proposed as key modulators of gamete/embryo maternal interactions. The aim of this study was to examine the metabolite content of oEVs and its regulation across the estrous cycle in cattle. Oviductal EVs were isolated from bovine oviducts ipsilateral and contralateral to ovulation at four stages of the estrous cycle (post-ovulatory stage, early and late luteal phases, and pre-ovulatory stage). The metabolomic profiling of EVs was performed by proton nuclear magnetic resonance spectroscopy (NMR). NMR identified 22 metabolites in oEVs, among which 15 were quantified. Lactate, myoinositol, and glycine were the most abundant metabolites throughout the estrous cycle. The side relative to ovulation had no effect on the oEVs' metabolite concentrations. However, levels of glucose-1-phosphate and maltose were greatly affected by the cycle stage, showing up to 100-fold higher levels at the luteal phase than at the peri-ovulatory phases. In contrast, levels of methionine were significantly higher at peri-ovulatory phases than at the late-luteal phase. Quantitative enrichment analyses of oEV-metabolites across the cycle evidenced several significantly regulated metabolic pathways related to sucrose, glucose, and lactose metabolism. This study provides the first metabolomic characterization of oEVs, increasing our understanding of the potential role of oEVs in promoting fertilization and early embryo development.

Long-term high-grain diet altered the ruminal pH, fermentation, and composition and functions of the rumen bacterial community, leading to enhanced lactic acid production in Japanese Black beef cattle during fattening

To increase intramuscular fat accumulation, Japanese Black cattle are commonly fed a high-grain diet from 10 to 30 months of age although it can result in the abnormal accumulation of organic acids in the rumen. We explored the effect of long-term high-concentrate diet feeding on ruminal pH and fermentation, and its effect on the rumen bacterial community in Japanese Black beef cattle during a 20-month fattening period. Nine castrated and fistulated Japanese Black beef cattle were housed with free access to food and water throughout the study period (10-30 months of age). The fattening stages included Early, Middle, and Late stages (10-14, 15-22, and 23-30 months of age, respectively). Cattle were fed high-concentrate diets for the experimental cattle during fattening. The body weight of the cattle was 439 ± 7.6, 561 ± 11.6, and 712 ± 18.5 kg (mean ± SE) during the Early, Middle, and Late stages, respectively. Ruminal pH was measured continuously during the final 7 days of each stage, and rumen fluid and blood samples were collected on day 4 (fourth day during the final 7 days of the pH measurements). The 24-h mean ruminal pH during the Late stage was significantly lower than that during the Early stage. Total volatile fatty acid (VFA) during the Late stage was significantly lower than during the Early and Middle stages, but no changes were noted in individual VFA components. The lactic acid concentration during the Late stage was significantly higher than that during the Early and Middle stages. The bacterial richness indices decreased significantly during the Late stage in accordance with the 24-h mean ruminal pH. Among the 35 bacterial operational taxonomic units (OTUs) shared by all samples, the relative abundances of OTU8 (Family Ruminococcaceae) and OTU26 (Genus Butyrivibrio) were positively correlated with the 24-h mean ruminal pH. Total VFA concentration was negatively correlated with OTU167 (Genus Intestinimonas), and lactic acid concentration was correlated positively with OTU167 and OTU238 (Family Lachnospiraceae). These results suggested that long-term high-grain diet feeding gradually lowers ruminal pH and total VFA production during the Late fattening stage. However, the ruminal bacterial community adapted to feeding management and the lower pH during the Late stage by preserving their diversity or altering their richness, composition, and function, to enhance lactic acid production in Japanese Black beef cattle.

Effect of recombinant bovine somatotropin (rbST) treatment on follicular population and development in non-lactating dairy cows

The aim of this study was to evaluate the long-term effects of recombinant bovine somatotropin (rbST) on follicle population and ovulatory follicle development in non-lactating dairy cows. Twenty-one Jersey cows were allocated in rbST (n=11) or control (n=10) groups. On day -60, cows in rbST group received 500 mg of somatotropin (s.c. Lactotropin®, Elanco). On day 0, control and rbST cows received an intravaginal progesterone-releasing device (1.9 g, CIDR^®, Zoetis) and GnRH (100 mg, IM, Factrel^®, Zoetis). On day 8, cows received PGF2α (25 mg, IM, Lutalyse®, Zoetis) and the CIDR^® was removed. Twelve hours after device removal (D8), serum, follicular fluid and granulosa cells samples were collected. Serum and follicular concentration of estradiol (E2) and progesterone (P4) were analyzed. Total RNA was extracted from granulosa cells to measure gene expression of LHCGR, STAR, HSD-3B1, CYP11A1, CYP19A1, CYP17A1, IGFR and PAPPA by real-time PCR. Ultrasonography was performed on days -60, -53, -46, -14, -7, 0 and 8 for antral follicle count. Results were analyzed by repeated measures ANOVA and t-test. There was no effect of rbST treatment on the number of follicles during the 60 days period, as well as no effect on serum and follicular fluid E2 and follicular fluid P4 at the moment of follicle aspiration. There was a reduction in PAPPA (P = 0.006), CYP11A1 (P = 0.04) and CYP19A1 (P = 0.002) mRNA levels in granulosa cells of the pre-ovulatory follicle of rbST treated cows. In conclusion, a single dose of rbST did not have long-term effects on antral follicle population, serum and follicular E2/P4 concentrations in non-lactating dairy cows. Despite that, rbST injection decreased granulosa cell expression of genes related to steroidogenesis in the pre-ovulatory follicle.

Purulent vaginal discharge diagnosed in pasture-based Holstein-Friesian cows at 21 days postpartum is influenced by previous lactation milk yield and results in diminished fertility

In a subset of dairy cows, prolonged pathological uterine inflammation results in purulent vaginal discharge (PVD), which can have negative consequences for both fertility and milk production. However, unlike for intensive systems, analysis of the effects of PVD in predominantly pasture-based herds is limited. The objective of this study was to assess the effect of PVD in spring-calving, pasture-based dairy cows on production and reproduction indices, stratified according to previous full-lactation milk yield. We assessed clinical disease as defined by vaginal mucus score (VMS) in 440 Holstein-Friesian cows from 5 farms. Cows were categorized as healthy (VMS 0) or having PVD (VMS 1-3) at 21 d postpartum. We recorded 305-d milk, milk protein, and milk fat yields (kg) before and after disease diagnosis, as well as fertility data, such as services per conception and the calving-conception period (CCP). Using SAS 9.4 (SAS Institute Inc., Cary, NC), we analyzed data using PROC MIXED, PROC PHREG, and PROC LOGISTIC to determine the least squares means differences and hazard and odds ratios between the groups, respectively. Overall, a 60% prevalence of PVD was recorded at 21 d postpartum. Milk yield and milk constituents were similar between all VMS categories and between healthy cows and cows with PVD. Although cows in the 4 VMS categories had statistically similar CCP, cows with PVD had a significantly longer CCP than healthy cows on average (9 d). The hazard ratio for cows with PVD was 0.66, indicating a 34% higher risk of a prolonged CCP than healthy cows. Odds ratio analysis determined that cows with PVD were 3 times more likely not to conceive at all, twice as likely not to conceive at first service, twice as likely not to conceive by 100 d postpartum, and 3 times more likely to fail to conceive before 150 d postpartum compared with healthy cows. Cows were retrospectively categorized as having low or high milk yield, based on whether they were above or below the median 305-d milk yield of the study population (6,571 kg) in the lactation before vaginal mucus scoring. Based on a univariate odds ratio, high-yield cows were 1.6 times more likely to present with PVD in the subsequent lactation. The number of services per conception did not differ between healthy and PVD cows in the low- and high-yield groups. In the high-yield group, cows with PVD were 4.9 times more likely not to conceive, 2.7 times more likely to require multiple services to conceive, 2.1 times more likely to remain not pregnant by 100 d postpartum, and 4.4 times more likely to remain not pregnant by 150 d postpartum. The CCP was also significantly longer in cows with PVD than their healthy counterparts (115.9 ± 4.9 and 104 ± 7.4 d, respectively). In conclusion, PVD significantly increased the CCP in all cows, but to a greater extent in cows with a high milk yield in the lactation before disease diagnosis.

The Effect of Abnormal Reproductive Tract Discharge on the Calving to Conception Interval of Dairy Cows

Prolonged calving-to-conception interval (CCI) can increase economic loss in cattle. We investigated the effect of post-calving abnormal reproductive tract discharge (ARTD) on CCI in dairy cows and quantified the relationship of ARTD and associated risk factors with CCI. The source population was dairy cows that calved in the study period on three pasture-based, year-round calving farms in the Riverina, NSW, Australia. Farm records and records from veterinarians' visits were analyzed. ARTD was defined as the presence of reproductive tract discharge according to the following classification: per vaginum purulent discharge ≥21 days post-calving or mucopurulent discharge >26 days post-calving. The incidence of ARTD was calculated. A Kaplan-Meier survivor function was used to estimate median time to conception post-calving dependent on the presence or absence of ARTD. Mixed effects Cox-proportional hazard models were used to estimate the direct and indirect effects of ARTD, and other potential risk factors on CCI such as body condition score (BCS), ambient temperature, and milk yield. Model structures were guided by a directed acyclic graph of potential risk factors for ARTD. The incidence of ARTD in lactations was 16% (95% CI 13.8–18.5%) and did not differ significantly between the three farms (P > 0.05). The median CCI was 176 and 118 days for lactations with and without ARTD, respectively (P < 0.01). The rate of pregnancy following calving in cows with ARTD was significantly decreased relative to the rate of pregnancy in cows without (total effect hazard ratio = 0.62, se = 0.18, P = 0.01). High peak milk yield (>32 L) and parity >2 also significantly extended CCI. We did not observe an effect of BCS or ambient temperature on CCI. The incidence of ARTD in the current study was consistent with clinical endometritis (considered a major source of ARTD) reported in other studies. In contrast—and despite regular veterinary assessment and treatment of on the farms in this study—ARTD extended CCI. Evaluation of the economic impact of ARTD on dairy farms in this region is warranted, and methods to identify high risk cows and develop effective interventions are required.

Novel sampling procedure to characterize bovine subclinical endometritis by uterine secretions and tissue

Subclinical endometritis (SE) in cattle is defined as clinically unapparent inflammation of the endometrium. It is reported to impair fertility in affected cows and causes economic loss within the dairy industry. A gold standard for diagnosis of SE has not been set. Uterine cytology and histopathology are both applied, but low agreement between these methods has been described. The objective of the present study was to assess the capability of uterine secretions (US) as a new medium for diagnosis of SE. A novel sampling tool was applied to retrieve US as well as cytological, histological and bacteriological samples of the endometrium after a singular passage through the cervix in 108 dairy cows (43-62 days post-partum [dpp]). To assess the quality of the US samples, a proteome analysis of samples from five healthy donors was performed, demonstrating that in vivo sampling of US was feasible and generated samples suitable for diagnostic purposes. Diagnosis of SE was realized by the combination of clinical, cytological, and histopathological findings. Quantitative analysis of pro- and anti-inflammatory cytokines (interleukin (IL)1B, IL6, IL8, IL17A, IL10) in US was conducted using AlphaLISA-technology. RNAlater-fixed endometrial biopsies were used for gene expression analysis of the cytokines IL1B, IL6, IL8, IL10 and tumor necrosis factor alpha (TNFα) as well as the prostaglandin-endoperoxide synthase 2 (PTGS2) and the antimicrobial peptide S100A9 by reverse transcription quantitative real-time polymerase chain reaction (RT-qPCR). Cows were assigned to groups according to their uterine health status. A large group of animals (n = 83) displayed no signs of endometritis (E.NEG). Cytological and histopathological examination revealed low agreement; hence, animals with SE were differentiated into SE(cyto) and SE(histo) groups (n = 7 and n = 13, respectively). One animal in group SE(cyto + histo) as well as four animals with signs of clinical endometritis (CE) were excluded from further analysis. SE(cyto) showed significantly higher median concentrations of IL1B, IL8 and IL17A in US as well as a significantly higher median expression of IL1B, IL8 and IL10 in endometrial biopsies compared to E.NEG. No significant differences were found for IL6 and IL10 in US and IL6, TNFα, PTGS2 and S100A9 in endometrial tissue between these groups. SE(histo) presented no differences concerning the analyzed parameters compared to E.NEG. In conclusion, a method to sample US was successfully established in dairy cows. The cytokines IL1B, IL8 and IL17A are promising candidates in diagnosing cytological endometritis by US. Further assessment of US might contribute to a better understanding of the pathological mechanisms leading to chronic endometrial inflammation and to impaired fertility in affected cows.

Genetic selection for bovine chromosome 18 haplotypes associated with divergent somatic cell score affects postpartum reproductive and metabolic performance

The susceptibility of animals to periparturient diseases has a great effect on the economic efficiency of dairy industries, on the frequency of antibiotic treatment, and on animal welfare. The use of selection for breeding cows with reduced susceptibility to diseases offers a sustainable tool to improve dairy cattle farming. Several studies have focused on the association of distinct bovine chromosome 18 genotypes or haplotypes with performance traits. The aim of this study was to test whether selection of Holstein Friesian heifers via SNP genotyping for alternative paternal chromosome 18 haplotypes associated with favorable (Q) or unfavorable (q) somatic cell scores influences postpartum reproductive and metabolic diseases. Thirty-six heifers (18 Q and 18 q) were monitored from 3 wk before calving until necropsy on d 39 (± 4 d) after calving. Health status and rectal temperature were measured daily, and body condition score and body weight were assessed once per week. Blood samples were drawn twice weekly, and levels of insulin, nonesterified fatty acids, insulin-like growth factor-I, growth hormone, and β-hydroxybutyrate were measured. Comparisons between the groups were performed using Fisher's exact test, chi-squared test, and the GLIMMIX procedure in SAS. Results showed that Q-heifers had reduced incidence of metritis compared with q-heifers and were less likely to develop fever. Serum concentrations of β-hydroxybutyrate were lower and insulin-like growth factor-I plasma concentrations were higher in Q- compared with q-heifers. However, the body condition score and withers height were comparable between haplotypes, but weight loss tended to be lower in Q-heifers compared with q-heifers. No differences between the groups were detected concerning retained fetal membranes, uterine involution, or onset of cyclicity. In conclusion, selection of chromosome 18 haplotypes associated with a reduced somatic cell score resulted in a decreased incidence of postpartum reproductive and metabolic diseases in this study. The presented data add to the existing knowledge aimed at avoiding negative consequences of genetic selection strategies in dairy cattle farming. The underlying causal mechanisms modulated by haplotypes in the targeted genomic region and immune competence necessitate further investigation.

Effects of l-arginine on endometrial estrogen receptor α/β and progesterone receptor expression in nutrient-restricted sheep

This study aimed to determine the effects of l-arginine (L-Arg) supplementation on steroid hormone receptors in non-pregnant ovine endometrium. All experimental ewes were randomly assigned to either a control group (n = 6), a nutrient-restricted group (n = 6), or an L-Arg supplemented nutrient-restricted group (n = 6). The effects of L-Arg on estrogen receptor α/β (ERα/β) and progesterone receptor (PGR) expression in the ovine endometrium were assessed. Our results showed that levels of ERβ and PGR expression were significantly increased by nutrient restriction, but L-Arg counteracted the effect of nutrient restriction on ERβ and PGR expression (p < 0.05). Also, expression of endometrial ERα was substantially increased (p < 0.05) by L-Arg supplementation. Furthermore, ERα/β and PGR were mainly detected in the endometrial luminal epithelium and glandular epithelium. Therefore, we isolated and identified endometrial epithelial cells (EECs) from sheep. Different concentrations of L-Arg were added to investigate the effects on ERα/β and PGR in EECs. The expression levels of endothelial nitric oxide synthase, ERβ, and PGR were significantly increased in response to low-concentration (200 μmol) L-Arg supplementation, which subsequently decreased with a high concentration (800 μmol) (p < 0.05). Otherwise, ERα expression was remarkably increased at both L-Arg concentrations in EECs (p < 0.05). Overall, the results indicated that L-Arg performed crucial roles in the regulation of ovine steroid hormone receptor expression in the endometrium. The results of this study provide a theoretical basis and technical means for the normal function of endometrium in response to low nutrient levels.

Associations between metabolic profiles, post-partum delayed resumption of ovarian function and reproductive performance in Egyptian buffalo: Roles of IGF-1 and antioxidants

This study was conducted on 47 pluriparous pregnant Egyptian buffalo. Body condition score (BCS) was classified and blood samples were collected pre-partum and post-partum for estimation of IGF-1, hormonal, metabolic and antioxidants values. There was palpation per rectum and ultrasonography in addition to quantitation of progesterone (P₄) and estradiol-17β (E-17β) for monitoring post-partum ovarian resumption. Reproductive indices were calculated 60, 90, 120 and 150 days post-partum. Based on the concentrations of P₄ and E-17β, buffalo were divided into ovulatory and non-ovulatory groups. The P₄ and E-17β were greater (P < 0.001) in ovulatory compared to non-ovulatory buffalo. The BCS and IGF-1 post-partum were greater (P =  0.024; 0.001, respectively) in ovulatory than non-ovulatory buffalo. Glucose and albumin were greater during pre- (P < 0.001; 0.013) and post-partum (P = 0.005; 0.003) periods in ovulatory than non-ovulatory buffalo. Post-partum, NEFA and BHBA concentrations were greater (P < 0.001) in non-ovulatory than ovulatory buffalo. The BUN concentrations were greater (P =  0.002) in non-ovulatory buffalo during pre- and post-partum periods. There were differences in GSH and SOD concentrations between groups (P < 0.001; 0.002, respectively). The BCS, albumin, IGF-1, GSH and SOD concentrations post-partum were negatively correlated with the delay of post-partum ovulation. The post-partum NEFA and BHBA concentrations, however, were positively correlated with delayed post-partum ovulation. Ovulatory buffalo had fewer (P < 0.01) days non-pregnant and for calving intervals as well as greater pregnancy rates than non-ovulatory buffalo. In conclusion, buffalo with delayed post-partum ovarian resumption were prone to have negative energy balance.

Sensor based eating time variables of dairy cows in the transition period related to the time to first service

In dairy cattle, reproductive diseases and infertility are some of the most important reasons for culling, where postpartum negative energy balance (NEB) reduces reproductive performance. This single cohort observational study reports the association between eating time and the interval between calving and first service in 2036 dairy cows on 17 commercial farms in The Netherlands. Cows were equipped with a commercially available neck sensor (Nedap, Groenlo, The Netherlands), that measured the time cows spent eating, from 28 days (d) before until 28 d after parturition. Primiparous cows spent a mean of +45 minutes (min) eating time per day ante partum and +15 min eating time post partum more than multiparous cows. A Cox proportional hazard model was used to analyze eating time variables in relation to the interval between calving and first service. From 4 weeks before until 4 weeks after calving eating time variables per week were used. Weeks -4, -3 + 3 and +4 were used as weeks with stable eating time patterns and therefore the mean eating time per week and the standard deviation of the mean eating time per week were used. Weeks -2, -1, +1 and +2 were addressed as periods with unstable eating patterns and therefore the slope in eating time per week and the residual variance of the slope per week were modeled. Significant results were the mean eating time in week -4 and +3 where in both weeks higher eating time lead to a higher hazard for first service. Difference between primiparous and multiparous cows were also significant with a higher hazard for first service for primiparous cows. Week 4 post partum presented a significant difference between eating time of primiparous cows and multiparous cows. These results display how eating time variables in the transition period could be related to the interval between calving and first service, and that there is a relation between mean eating time in week -4, +3, +4 and the interval between calving and first insemination.

Elevated free fatty acids affect bovine granulosa cell function: a molecular cue for compromised reproduction during negative energy balance

High-yielding dairy cows postpartum face the challenge of negative energy balance leading to elevated free fatty acids levels in the serum and follicular fluid thus affecting the ovarian function. Here, we investigated effects of physiological concentrations of palmitic acid (PA), stearic acid (SA) and oleic acid (OA) on the viability, steroid production and gene expression in a bovine granulosa cell (GC) culture model. Treatment with individual and combined fatty acids increased the CD36 gene expression, while no significant apoptotic effects were observed. Both PA and SA significantly upregulated the expression of FSHR, LHCGR, CYP19A1, HSD3B1, CCND2 and increased 17β-estradiol (E2) production, while OA downregulated the expression of these genes and reduced E2. Interestingly, STAR was equally downregulated by all fatty acids and combination treatment. E2 was significantly reduced after combination treatment. To validate the effects of OA, in vivo growing dominant follicles (10-19 mm) were injected with bovine serum albumin (BSA) with/without conjugated OA. The follicular fluid was recovered 48 h post injection. As in our in vitro model, OA significantly reduced intrafollicular E2 concentrations. In addition, expression of CD36 was significantly up- and that of CYP19A1 and STAR significantly downregulated in antral GC recovered from aspirated follicles. The ovulation rates of OA-injected follicles tended to be reduced. Our results indicate that elevated free fatty acid concentrations specifically target functional key genes in GC both in vitro and in vivo. Suggestively, this could be a possible mechanism through which elevated free fatty acids affect folliculogenesis in dairy cows postpartum.

Blood metabolite concentration, milk yield, resumption of ovarian activity and conception in grazing dual purpose cows supplemented with concentrate during the post-partum period

Cattle grazing on natural pasture face seasonal variation in pasture availability and nutritive value. Improving the nutrition of cows by providing supplementary feeds during periods of pasture or nutrient deficit is necessary for improved productivity. This study was conducted to determine the effect of feed supplementation during the post-partum period on the metabolic status and reproductive performance of 40 grazing Sanga and Friesian × Sanga cows. Twenty out of a total of 40 cows (10 Sanga and 10 Friesian × Sanga cows) were supplemented with 2.5 kg of concentrate per day for 16 weeks after calving. Parameters measured include daily milk yield, concentration of blood metabolites, resumption of ovarian activity and conception. Supplemented cows had higher partial milk yield than their non-supplemented counterparts (2.07 vs. 1.60 kg/day; P < 0.001). Sanga cows had lower milk yield than the Friesian × Sanga crossbreds (1.61 vs. 2.05 kg/day; P < 0.01). Supplemented cows had higher mean total protein (86.7 vs. 81.3 g/L; P = 0.007) and globulin (53.0 vs. 47.7; P = 0.014) concentrations than non-supplemented cows. Sanga cows had higher glucose (P = 0.027), total protein (P < 0.001) and globulin (P < 0.001) but lower triglyceride (P = 0.003) and progesterone (P = 0.023) concentrations than Friesian × Sanga cows. Supplemented cows had less proportion not cycling (20 vs. 55%; P = 0.022) and less days open (95.8 vs. 106 days; P = 0.032) than non-supplemented cows. The Friesian × Sanga cows had higher progesterone concentrations at first progesterone rise (3.34 vs. 1.32 ng/mL; P = 0.032) and shorter interval from calving to conception (96.7 vs. 106 days; P = 0.042). The results from this study indicate the beneficial effects of feed supplementation in terms of increased milk yield, better metabolic status and reproductive performance.

Effects of plane of nutrition and arginine on ovarian follicles in non-pregnant sheep: Cell proliferation, and expression of endothelial nitric oxide and its receptor

The aim of this study was to investigate the role of the nitric oxide (NO) system in ovarian function, by determining if arginine (Arg) supplementation impacts follicle number, cell proliferation, and expression of the NO system members in nutritionally compromised ewes. Ewes were randomly assigned into maintenance (C, 100% requirements), excess (O; 2xC), or restricted (U; 0.6xC) diets 8 weeks prior to Arg treatment. Ewes were individually fed twice daily with pelleted diets. Ewes from each nutritional group were randomly assigned to one of two treatments: saline or Arg, which was initiated on day 0 of the estrous cycle and administered 3 times per day. Ovaries were collected at the early-luteal, mid-luteal and late-luteal/follicular phases of the estrous cycle to determine 1) the number of surface follicles, 2) follicle cell proliferation marked by Ki67 protein expression, and 3) expression of endothelial nitric oxide (eNOS; NOS3) and soluble guanylyl cyclase beta (sGC; GUCY1B3) protein and mRNA in granulosa (G) and theca (T) layers using immunohistochemistry followed by image analysis and qPCR, respectively. During nutritional treatment, C maintained body weight, O gained 6±1.2 kg, and U lost 14±1.3 kg. Our data show that: 1) Ki67 was expressed in all ovarian compartments, eNOS protein was detected in blood vessels of T and stroma, and sGC protein was detected in T cells, and blood vessels of T layer and other ovarian compartments; 2) plane of nutrition affected the number of surface follicles, and thus folliculogenesis, cell proliferation in the T layer, eNOS and sGC protein expression in T, and NOS3 and GUCY1B3 mRNA expression in G; 3) Arg treatment affected cell proliferation in G and T, eNOS and sGC protein expression in T, mRNA expression of NOS3 in T in all groups, and GUCY1B3 in G depending on the stage of the estrous cycle; and 4) G and T cell proliferation, and expression of eNOS and sGC protein in T was affected by the stage of the estrous cycle. Our data demonstrated that plane of nutrition and Arg are involved in the regulation of follicular functions in non-pregnant sheep.

Uterine inflammation and fertility of beef cows subjected to timed AI at different days postpartum

The aim of this study was to evaluate the uterine health and fertility of postpartum beef cows subjected to timed AI (TAI) protocols at different days from calving. Lactating Nelore cows (Bos indicus; n = 244) were used in this study. The TAI protocols were initiated between 20 and 60 days postpartum (DPP). Cows were subjected to an estradiol-progesterone based TAI protocol. The cows were divided into three groups according to the days postpartum at the time the hormonal treatment was initiated: 1) Early (n = 64), cows between 20 and 30 DPP; 2) Middle (n = 115), cows between 31 and 45 DPP; and 3) Late (n = 65), cows between 46 and 60 DPP. At Day 0 of the protocol, endometrial cytobrush samples were collected. Slides for polymorphonuclear (PMN) cell counting were prepared and cytobrush was used for RNA extraction and analysis of relative abundance of il1, il6, il8, and tnf mRNA. Cows from the Early group had less (P < 0.05) pregnancies per AI (P/AI) than cows from Middle and Late groups; 29.7% (19/64), 45.2% (52/115), and 52.31% (34/65), respectively. Accordingly, the Early group had a greater (P < 0.05) proportion of PMN cells in the uterus than Middle and Late groups; 9.0%, 3.8%, and 2.2%, respectively. Relative abundances of il1 and il8 mRNA were greater (P < 0.05) in the Early group than Middle and Late groups. These results indicate that beef cows subjected to TAI protocols early postpartum (< 30 DPP) are less likely to become pregnant, which is associated with increased inflammation and relative abundance of mRNA for the proinflammatory cytokines il1 and il8.