Reproductive traits of Holsteins and Jerseys. Effects of age, milk yield, and clinical abnormalities on involution of cervix and uterus, ovulation, estrous cycles, detection of estrus, conception rate, and days open

Combining reproductive outcomes predictors and automated estrus alerts recorded during the voluntary waiting period identified subgroups of cows with different reproductive performance potential

The objective was to compare differences in reproductive performance for dairy cows grouped based on the combination of data for predictors available during the prepartum period and before the end of the VWP, automated estrus alerts (AEA) during the VWP, and the combination of both factors. In a cohort study, data for AEA and potential predictors of the percentage of cows that receive insemination at detected estrus (AIE) and pregnancies per AI (P/AI) for first service, and the percentage of cows pregnant by 150 DIM (P150) were collected from -21 to 49 DIM for lactating Holstein cows (n = 886). The association between each reproductive outcome with calving season (cool, warm), calving-related events (yes, no), genomic daughter pregnancy rate (gDPR; high, medium, low), days in the close-up pen (ideal, not ideal), health disorder events (yes, no), rumination time (high or low CV prepartum and high or low increase rate postpartum), and milk yield (MY) by 49 DIM (high, medium, low) were evaluated in univariable and multivariable logistic regression models. Individual predictors (health disorders, gDPR, and MY) associated with the 3 reproductive outcomes in all models were used to group cows based on risk factors (RF; yes, n = 535 or no, n = 351) for poor reproductive performance. Specifically, cows were included in the RF group if any of the following conditions were met: the cow was in the high MY group, had low gDPR, or had at least one health disorder recorded. Cows were grouped into estrus groups during the VWP based on records of AEA (E-VWP, n = 476 or NE-VWP, n = 410). Finally, based on the combination of levels of AEA and RF cows were grouped into an estrus and no RF (E-NoRF, n = 217), no estrus and RF (NE-RF, n = 276), no estrus and no RF (NE-NoRF, n = 134), and estrus and RF (E-RF, n = 259) groups. Cows received AIE up to 31 d after the end of the VWP, and if did not receive AIE, received timed AI after an Ovsynch plus progesterone protocol. Logistic and Cox proportional hazard regression compared differences in reproductive outcomes for different grouping strategies. The NoRF (AIE:76.9%; P/AI:53.1%; P150:84.5%) and E-VWP (AIE:86.8%; P/AI:44.8%; P150:82.3%) groups had more cows AIE, P/AI, and P150 than the RF (AIE:64.5%; P/AI:34.9%; P150:72.9%) and NE-VWP (AIE:50.0%; P/AI:38.9%; P150:72.1%) groups, respectively. When both factors were combined, the largest and most consistent differences were between the E-NoRF (AIE:91.3%; P/AI:58.7%; P150:88.5%) and NE-RF groups (AIE:47.3%; P/AI:35.8%; P150:69.5%). Compared with the whole population of cows or cows grouped based on a single factor, the E-NoRF and NE-RF groups had the largest and most consistent differences with the whole cow cohort. The E-NoRF and NE-RF group also had statistically significant differences of a large magnitude when compared with the remaining cow cohort after removal of the respective group. We conclude that combining data for AEA during the VWP with other predictors of reproductive performance could be used to identify groups of cows with larger differences in expected reproductive performance than if AEA and the predictors are used alone.

Dissecting the genomic regions of selection on the X chromosome in different cattle breeds

Mammalian X and Y chromosomes independently evolved from various autosomes approximately 300 million years ago (MYA). To fully understand the relationship between genomic composition and phenotypic diversity arising due to the course of evolution, we have scanned regions of selection signatures on the X chromosome in different cattle breeds. In this study, we have prepared the datasets of 184 individuals of different cattle breeds and explored the complete X chromosome by utilizing four within-population and two between-population methods. There were 23, 25, 30, 17, 17, and 12 outlier regions identified in Tajima's D, CLR, iHS, ROH, FST, and XP-EHH. Bioinformatics analysis showed that these regions harbor important candidate genes like AKAP4 for reproduction in Brown Swiss, MBTS2 for production traits in Brown Swiss and Guernsey, CXCR3 and CITED1 for health traits in Jersey and Nelore, and BMX and CD40LG for regulation of X chromosome inactivation in Nelore and Gir. We identified genes shared among multiple methods, such as TRNAC-GCA and IL1RAPL1, which appeared in Tajima's D, ROH, and iHS analyses. The gene TRNAW-CCA was found in ROH, CLR and iHS analyses. The X chromosome exhibits a distinctive interaction between demographic factors and genetic variations, and these findings may provide new insight into the X-linked selection in different cattle breeds.

Association of dry matter intake, milk yield, and days to first ovulation with cytological endometritis in Holstein cows

Dry matter intake (DMI, kg/d) is closely related to the magnitude of negative energy and protein balance during the transition period, and the metabolic adaptations to support lactation in dairy cows. Thus, DMI might affect the development of cytological endometritis in the early postpartum period. Difficulty to adapt to these metabolic changes is related to impaired immune function and increased occurrence of reproductive disorders. We aimed to examine the association of pre- and postpartum DMI, body weight (BW), body condition score, milk yield and milk composition, and days to first ovulation with cytological endometritis at 15 (CYT15) and 30 DIM (CYT30). A second objective was to understand the association of vaginal discharge with CYT15 and CYT30 and performance. We conducted a pooled statistical analysis of 5 studies, including data from 280 multiparous Holstein cows. Based on the cutoffs for the percentage of uterine polymorphonuclear cells (PMN), determined by taking the median value of the data set for 15 and 30 DIM, cows were categorized as follows: LOW15 (PMN % at 15 DIM ≤24%; n = 125), HIGH15 (PMN % at 15 DIM >24%; n = 125), LOW30 (PMN % at 30DIM ≤7%; n = 141); and HIGH30 (PMN % at 30DIM >7%; n = 139). Cows in HIGH15 consumed an average of 1.97 ± 0.5 kg/d less DM than cows in LOW15 during prepartum, and 3.01 ± 0.5 kg/d less DM during postpartum. Dry matter intake (as a percentage of BW) was higher for cows in LOW15 during pre- and postpartum than for cows in HIGH15. Moreover, cows in HIGH15 tended to have lower milk yield than cows in LOW15 from the third until the fifth week postpartum. Although DMI was not associated with CYT30, DMI (as a percentage of BW) was lower for cows in LOW30 pre- and postpartum than for cows in HIGH30. There was no association between CYT30 and milk yield. Cows in LOW15 had greater days to first ovulation than cows in HIGH15, while cows in LOW30 also had greater days to first ovulation than cows in HIGH30. Simple regression analyses demonstrated linear associations of increased DMI, particularly postpartum, with decreased uterine PMN percentage and lower vaginal discharge score. Additionally, increased units of vaginal discharge score and increased percentage units of uterine PMN were linearly associated with decreased milk yield. Corroborating with the notion of the ovarian function being associated with uterine inflammatory status, cows in HIGH15 and HIGH30 ovulated on average 3 d before than cows in LOW15 and LOW30, respectively. Cytological endometritis at 15 DIM was associated with lower DMI from 4 wk before calving until 4 wk postpartum and was associated with lower milk yield. The association of vaginal discharge with cytological endometritis was variable and dependent on the day of evaluation.

Effect of a targeted reproductive management program designed to prioritize insemination at detected estrus and optimize time to insemination on the reproductive performance of lactating dairy cows

The primary objective of this randomized controlled experiment was to evaluate the insemination dynamic and reproductive performance of cows managed with a targeted reproductive management (TRM) program designed to prioritize artificial insemination (AI) at detected estrus (AIE) and optimize timing of AI by grouping cows based on detection of estrus during the voluntary waiting period (VWP). Our secondary objective was to evaluate reproductive outcomes for cows with or without estrus during the VWP. Lactating Holstein cows fitted with an ear-attached sensor for detection of estrus were randomly assigned to a TRM treatment that prioritized AIE based on detection of estrus during the VWP (TP-AIE; n = 488), a non-TRM treatment that prioritized AIE (P-AIE; n = 489), or an all-timed AI (TAI) treatment with extended VWP (ALL-TAI; n = 491). In TP-AIE, cows with or without automated estrus alerts (AEA) recorded during the VWP received AIE if detected in estrus for at least 31 ± 3 or 17 ± 3 d after a 49 d VWP, respectively. Cows not AIE with or without AEA during the VWP received TAI after Ovsynch with progesterone supplementation and 2 PGF_2α treatments (P4-Ov) at 90 ± 3 or 74 ± 3 d in milk (DIM), respectively. In P-AIE, cows received AIE if detected in estrus for 24 ± 3 d after a 49 d VWP, and if not AIE received TAI at 83 ± 3 DIM after P4-Ov. In ALL-TAI, cows received TAI at 83 ± 3 DIM after a Double-Ovsynch protocol. Data were analyzed by logistic and Cox's proportional hazard regression. The proportion of cows AIE did not differ for TP-AIE (71.0%) and P-AIE (74.6%). Overall P/AI at 39 d after first service was greater for the ALL-TAI (47.6%) than for the P-AIE (40.2%) and TP-AIE (39.5%) treatments. The hazard of pregnancy up to 150 DIM was greater for cows in TP-AIE (hazard ratio (HR) = 1.2; 95% confidence interval: 1.1-1.4) and P-AIE (hazard ratio = 1.2; 95% confidence interval: 1.1-1.4) than for cows in the ALL-TAI treatment which resulted in median time to pregnancy of 89, 89, and 107 d. Conversely, the proportion of cows pregnant at 150 DIM did not differ (ALL-TAI 78.5%, P-AIE 76.3%, TP-AIE 76.0%). Except for a few outcomes for which no difference was observed, cows detected in estrus during the VWP had better performance than cows not detected in estrus. Cows with AEA during the VWP were more likely to receive AIE, had greater P/AI, and greater pregnancy rate up to 150 DIM regardless of first service management. We conclude that a TRM program designed to prioritize AIE by grouping cows based on detection of estrus during the VWP was an effective strategy to submit cows for first service resulting in similar or improved performance than a non-TRM program that prioritized AIE or an all-TAI program with extended VWP. Also, AEA recorded during the VWP might be used as a strategy for identifying subgroups of cows with different reproductive performance.

Ovarian and uterine haemodynamics and their relation to steroid hormonal levels in postpartum Egyptian buffaloes

The current study aimed to assess the ovarian and uterine haemodynamics in postpartum (pp) Egyptian buffaloes and their relation to steroid hormonal levels (progesterone and estrogen). Six multiparous buffalos with normal calving were examined by using trans-rectal Doppler sonography to assess the blood flow in ipsilateral and contralateral ovarian and uterine arteries. Doppler parameters viz. peak systolic velocity (PSV), blood flow volume (BFV), resistance (RI) and pulsatility index (PI) were measured at 1st till 6th postpartum weeks. In addition, diameters (mm) of the ovarian and uterine arteries and the vascularisation area (mm2) of ovary were determined. The blood samples were collected starting from 1st week post calving and every week thereafter following each ultrasound Doppler examination for assay of progesterone and estradiol. Results indicated that PI and RI increased consistently and significantly (P<0.05) till the 6th week post calving as compared to those recorded at 1st week in ipsilateral ovarian and uterine arteries. However, the blood flow volume and peak systolic velocity in both ovarian and uterine arteries decreased gradually from 1st week till the 6th week after calving. There were very strong positive correlations between PSV and BFV, in both ipsilateral and contralateral ovarian and uterine arteries. Blood concentrations of progesterone were lower (P<0.05) during the first four weeks than those recorded at 5th and 6th postpartum weeks. This trend was reversed for blood estradiol 17-β. The results of the present investigation concluded that Doppler ultrasonography is a suitable tool for assessing changes in ovarian and uterine perfusion during the puerperium.

Accessory corpus luteum induced by human chorionic gonadotropin on day 7 or days 7 and 13 of the estrous cycle affected follicular and luteal dynamics and luteolysis in lactating Holstein cows

Our objective was to determine the effect of inducing an accessory corpus luteum (CL) with human chorionic gonadotropin (hCG; 3,300 IU) on d 7 (hCG7) or 2 accessory CL with hCG on d 7 and 13 (hCG7+13) of the estrous cycle in noninseminated lactating Holstein cows. Cows (n = 86) between 39 and 64 DIM were pretreated with an Ovsynch + CIDR protocol, and only synchronized cows were used (n = 64). The day of the last GnRH of Ovsynch was considered d 0 of the estrous cycle. Follicular and luteal dynamics of cows were evaluated daily during an entire estrous cycle by ovarian ultrasonography. Blood samples were collected daily to measure serum concentration of progesterone (P4). Cows were randomly assigned to CON (n = 22, no treatment), hCG7 (n = 20), or hCG7+13 (n = 22) treatments. Two cows from hCG7+13 failed to ovulate after hCG and were removed from the analyses post-hCG treatment. The first day of luteolysis was considered the day that P4 declined to more than 2 SD of the mean for the 4 consecutive P4 concentrations with the greatest mean in late diestrus for each individual cow. The P4 cut-off for complete luteolysis was <1.0 ng/mL. Mean P4 on d 7 (3.23 ± 0.16 ng/mL) did not differ among treatments. Cows treated with hCG had greater total luteal and original CL volume and serum P4 during diestrus than CON. Cows treated with hCG7+13 had greater serum P4 after d 13 of the cycle than hCG7. Cycles were classified as having atypical cycles if the dominant follicle or future dominant follicle at the time of luteolysis did not ovulate (delayed ovulation; CON, n = 2; hCG7, n = 4; hCG7+13, n = 3), had a short cycle (CON, n = 1), delayed (CON, n = 2) or incomplete luteolysis (CON, n = 1; hCG7, n = 4; hCG7+13, n = 5). The remainder of cycles with normal complete luteolysis followed by ovulation were considered to be typical. Based on blood perfusion, the CON cow with incomplete luteolysis had 2 original CL remaining functional after first onset of luteolysis. The rest of the cows with incomplete luteolysis (9/10) had one or more CL regressing and at least one remaining functional after first onset of luteolysis. No specific pattern for CL side (ipsilateral vs. contralateral to a CL with complete regression) was observed for nonregressed CL. Cows with incomplete luteolysis had a second onset of luteolysis to undergo complete functional luteolysis. The proportion of cows with typical cycle was 73% (16/22) for CON, 60% (12/20) for hCG7, and 55% (11/20) for hCG7+13. Cows with typical cycles treated with hCG (hCG7 and hCG7+13) had a later onset of luteolysis, prolonged time to undergo complete luteolysis, and greater proportion of cows with 3 follicular waves than CON, resulting in a longer interovulatory interval for hCG7 and hCG7+13 than CON. In summary, accessory CL induced by hCG during diestrus not only altered follicular and luteal dynamics but also deferred and prolonged the luteolytic process.

Effects of GnRH and hCG administration during early luteal phase on estrous cycle length, expression of estrus and fertility in lactating dairy cows

Our objective was to determine the effects of a single treatment of human chorionic gonadotropin (hCG) or GnRH from d 5 to 7 of the estrous cycle on cycle length, expression of estrus and fertility in lactating dairy cows. Lactating Holstein cows (n = 354) located in Farm 1 and lactating Jersey cows located in Farm 2 (n = 210) detected in estrus by an Automated Activity Monitor (AAM) system from 27 to 50 days in milk (DIM) were randomly assigned to receive one of three treatments from d 5 to 7 of the estrous cycle: control (untreated; CON; Holstein, n = 111; Jersey, n = 66), GnRH (86 μg gonadorelin acetate im; Holstein, n = 116; Jersey, n = 75), or hCG (3,300 IU im; Holstein, n = 127; Jersey, n = 69). Ovaries were scanned with ultrasound in a random subgroup of cows (Holstein/Farm 1, n = 147; Jersey/Farm 2, n = 94) on the day of treatment and 3 or 4 d later to determine ovulation. Estrus was detected after treatment by an AAM, and peak activity and heat index were recorded. A random subgroup of cows observed in estrus after treatment received first AI from 51 to 80 DIM (Holstein, n = 208; Jersey, n = 138). Pregnancy diagnoses were performed by transrectal ultrasonography at 37 ± 3 d post-AI. Holstein and Jersey cows treated with GnRH and hCG had an increased (P < 0.05) ovulatory response compared with controls. Human chorionic gonadotropin decreased (74%; P = 0.05) and GnRH tended to reduce (75%; P = 0.07) the proportion of multiparous Holstein cows returning to estrus compared with CON (86%). Cows treated with hCG had a longer (P < 0.01) estrous cycle length (24.6 ± 0.3 d, Holstein; 23.0 ± 0.3 d, Jersey) compared with CON cows (22.7 ± 0.3 d, Holstein; 21.3 ± 0.3 d Jersey) and GnRH (22.9 ± 0.3 d, Holstein; 21.1 ± 0.3 d Jersey). The percentage of cows with high (≥80) peak activity and heat index did not differ (P > 0.50) between treatments, and milk production did not affect (P > 0.65) the duration of estrus. Pregnancy per AI (P/AI) was not affected by treatments in Holstein (P = 0.93; CON: 34.3%, GnRH: 35.4%, and hCG: 31.5%) and in multiparous Jersey cows (P = 0.35; CON: 34.3%, GnRH: 35.4%, and hCG: 31.5%), but hCG had greater (P = 0.03; 55%) P/AI than GnRH (30.0%) and a trend (P = 0.06) for greater P/AI than CON (33.3%) in primiparous Jersey cows. In summary, inducing the formation of an accessory corpus luteum from d 5 to 7 of the estrous cycle with hCG reduced expression of estrus in multiparous Holstein cows. Moreover, hCG increased estrous cycle length in Holstein and Jersey cows, and it did not affect first service P/AI at 37 ± 3 d post-AI in Holstein and multiparous Jersey lactating cows. However, hCG increased P/AI in primiparous Jersey cows. Future research with a larger number of cows is needed to confirm these intriguing fertility results.

Association of low serum calcium concentration after calving with productive and reproductive performance in multiparous Jersey cows

Consequences of postpartum low blood calcium (Ca) concentration are still under study and literature describing this condition in Jersey cows is scarce. A prospective cohort study was conducted to evaluate the association of low serum Ca concentration shortly after calving with milk and energy-corrected milk yields, somatic cell count linear score, and pregnancy to first service and within 150 d in milk in multiparous Jersey cows from 2 commercial herds. Blood samples for serum Ca determination were collected on average at 3 h 10 min postpartum from 352 multiparous Jersey cows. Productive data up to the 10th monthly test were obtained from the Dairy Herd Improvement Association and reproductive data were obtained from herd records. Multiple linear, log-binomial, and Cox's proportional hazards regressions were used to evaluate the association of low serum Ca concentration with productive and reproductive outcomes. Serum Ca concentration ≤2.18 mmol/L was associated with 1.43 and 1.85 kg/d more milk and energy-corrected milk. However, lower serum Ca concentrations were associated with a 0.28-unit-higher somatic cell count linear score per monthly test (Ca ≤2.00 mmol/L), and decreased pregnancy risk at first service (risk ratio = 0.64; Ca ≤1.94 mmol/L) and hazard of pregnancy within 150 d in milk (hazard ratio = 0.40; Ca ≤1.90 mmol/L). The present study is based on a convenience sample of multiparous Jersey cows from 2 commercial herds; further research including more herds and additional blood Ca determinations is needed to describe postpartum blood Ca dynamics and its association with productive and reproductive outcomes for the Jersey breed.

Transition cow metabolites and physical traits influence days to first postpartum ovulation in dairy cows

Physical activities are associated with the health of transition dairy cows and pregnancy outcomes are positively related to early resumption of postpartum estrous cycles. The objective was to assess key metabolites and patterns of prepartum and postpartum physical activity as they relate to the onset of first postpartum ovulation in lactating dairy cows. Close-up dry Holstein cows (n = 82) and late gestation heifers (n = 78) were enrolled beginning 3 wk before expected calving date (Day 0). Cows were fit with Cow SensOor ear tags to assess transitional changes in eating, resting, rumination, high activity, and ear-surface temperatures. Rectal temperatures were assessed and blood samples were collected on Days 0, 3, 7, and 14 to measure concentrations of glucose, free fatty acids (FFA), β-hydroxybutyrate (BHB), calcium, and haptoglobin. Body condition scores (BCS) and body weights (BW) were measured weekly, and blood samples were collected weekly from Day 21 ± 3 through 70 ± 3 to quantify changes in progesterone to detect luteal function after ovulation. Cows first ovulating before median Day 33 were classified as early (n = 76), whereas those first ovulating after Day 33 were classified as late (n = 84). Early ovulating cows first ovulated earlier (P < 0.001) than the late ovulation cows (24.3 ± 1.2 d [range: 16-32 d] vs. 48.8 ± 1.2 d [range: 33-74 d]), respectively. Mean days to first ovulation excluded seven cows that failed to ovulate before insemination. Compared with late ovulating cows, early ovulating cows had lesser (P < 0.05) concentrations of FFA, BHB, and haptoglobin on Days 0, 3, 7, and 14 in addition to having lesser (P < 0.05) rectal temperatures and ear-surface temperatures. Ear-surface temperatures began to decrease 4 d before parturition and remained less (P < 0.05) after calving than cows that subsequently ovulated late. Early ovulating cows tended (P = 0.07) to spend more time eating, and less (P = 0.02) time resting and being active during the first 3 wk after calving, and lost less (P = 0.03) BW and BCS during the first 9 wk compared with late ovulating cows. Although no differences were detected in yields of milk or energy-corrected milk during the first 9 wk after calving, early compared with late ovulating cows produced more (P < 0.01) milk protein. We concluded that metabolic measures during the first 2 wk after calving, and physical and behavioral traits are associated with the onset of postpartum ovarian activity.

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.

Effect of flunixin meglumine and aspirin administration on conception rate and estrous cycle characteristics of Egyptian Baladi cows during hot season

The current investigation aims to evaluate the effects of flunixin meglumine (FM) and aspirin as non-steroid anti-inflammatory drug (NSAID) administration on estrous cycles characteristics and conception rate of Egyptian Baladi cows during hot season. In the first phase, 30 cows were divided into 3 groups, 10 cows for each treatment. The first group was treated with FM at the rate of 1.1 mg/kg body weight (BW) intramuscular, while the second group was administrated aspirin solution orally at the rate of 50 mg/kg BW. The third group was assigned as control (CG) that has no treatment. The FM group was administrated on day 14 after mating, while aspirin was given on day 14 and day 15 post-mating. All cows were mated naturally after showing estrus signs. Pregnancy diagnosis was carried 60 days after mating by rectal palpation. In the second phase, cows were monitored for estrus behavior by visual observation twice a day. The length of normal estrous cycles was 20, 23, and 22 days in cows treated with FM, aspirin, and control cows, respectively. There was no significant effect of treatment on the length of normal estrous cycles in Egyptian cows (P < 0.05). Proportions of long cycles in Egyptian cows that treated with FM or aspirin and control were 75, 67.7, and 57.1%, respectively. Short cycles were completely absent in cows that treated with FM or aspirin, but it was 29% in CG. Mounting behavior and tail rising were not detected in CG compared to 0 and 33% in FM or 25 and 33% in aspirin treated cows, respectively. Conception or pregnancy rate were 60, 40, and 30%, respectively, in FM, aspirin treated, and CG. Treatment cows whether FM or aspirin group did not influence (P < 0.05) progesterone concentration during the 14 days and 21 days from estrous cycle in pregnant and non-pregnant Egyptian Baladi cows than CG. In conclusion, the results of this study clearly indicated beneficial effect of FM and aspirin administration on intense of displayed estrous behavior and conception rate of Egyptian Baladi cows during the hot season.

Associations of cigarette smoking with gray and white matter in the UK Biobank

Cigarette smoking is associated with increased risk for myriad health consequences including cognitive decline and dementia, but research on the link between smoking and brain structure is nascent. In the current study, we assessed the relationship of cigarette smoking with gray matter (GM) and white matter (WM) in the UK Biobank, controlling for numerous confounding demographic and health variables. We used negative-binomial regression to model the association of cigarette smoking (having ever smoked regularly, cigarettes per day, and duration smoked) with GM and WM (GM N = 19,615; WM N = 17,760), adjusting for confounders. Ever smoked and duration were associated with smaller total GM volume. Ever smoked was associated with reduced volume of the right VIIIa cerebellum and elevated WM hyperintensity volume. Smoking duration was associated with reduced total WM volume. Regarding specific tracts, ever smoked was associated with reduced fractional anisotropy in the left cingulate gyrus part of the cingulum, left posterior thalamic radiation, and bilateral superior thalamic radiation, and increased mean diffusivity in the middle cerebellar peduncle, right medial lemniscus, bilateral posterior thalamic radiation, and bilateral superior thalamic radiation. This study identified significant associations of cigarette exposure with global measures of GM and WM, and select associations of ever smoked, but not cigarettes per day or duration, with specific GM and WM regions. By controlling for important sociodemographic and health confounders, such as alcohol use, this study identifies distinct associations between smoking and brain structure, highlighting potential mechanisms of risk for common neurological sequelae (e.g., dementia).

A shortened resynchronization treatment for dairy cows after a nonpregnancy diagnosis

We hypothesized that a shortened version of a modified Ovsynch program (OVS: GnRH-1 - 7 d - PGF_2α-1 - 24 h - PGF_2α-2 - 32 h - GnRH-2 - 16 h - AI) that excluded GnRH-1 to resynchronize ovulation in cows bearing a corpus luteum (CL) after a non-pregnancy diagnosis (NPD) or including progesterone supplementation with the OVS treatment for cows without a CL would produce shorter inter-insemination intervals and pregnancy per AI (P/AI) not different from that of cows treated with the OVS treatment. Of the 1697 lactating Holstein cows enrolled in this experiment, complete data were available for only 1584 cows because the remainder was not treated, inseminated per treatment design, left the herd before pregnancy diagnosis, or some other outcome was missing. Cows were enrolled in the study and assigned to either of three treatments at NPD (32 ± 3 d after AI [Day 0]). Cows with a detected CL were assigned randomly to: (1) a modified Ovsynch (OVS; GnRH-1 - 7 d - PGF_2α-1 - 24 h - PGF_2α-2 - 32 h - GnRH-2 - 16 h - AI) or (2) Short Synch (SS; PGF_2α-1 - 24 h - PGF_2α-2 - 32 h - GnRH-2 - 16 h - AI). Cows with no CL were assigned to OVS plus a progesterone insert (CIDR). Blood was collected at NPD to measure progesterone concentration and determine accuracy of treatment assignment (progesterone ≥ 1 ng/mL for a functional CL). Overall progesterone concentration at NPD was less in OVS + CIDR cows (1.5 ± 0.3 ng/mL) than in OVS (5.2 ± 0.2 ng/mL) or SS cows (3.7 ± 0.3 ng/mL). No differences in luteolytic risk (progesterone < 0.5 ng/mL at 72 h after PGF_2α-1) were detected after PGF_2α (>96.7%) and ovulation risk after GnRH-2 was 93.8, 91.7, and 86.2% for SS, OVS, and OVS + CIDR, respectively. Mean and median inter-insemination interval were less in SS (mean = 34.3 ± 0.05 d [median = 35 d] than OVS cows (40.2 ± 0.05 d [42 d]), but that in OVS cows did not differ from OVS + CIDR cows (41.4 ± 0.05 d [42 d]). Technicians were more accurate in visually detecting a functional CL than a non-functional CL (81.2 vs. 61.1%). Sensitivity of detecting a functional CL by technicians averaged 91.2%, but specificity was 39.8%. Pregnancy per AI at 32 ± 3 d after AI was less for SS (16.5% [n = 115]) than OVS (29.3% [n = 133] when a functional CL was inaccurately detected, but did not differ when a functional CL was detected accurately (27.6% [n = 561] vs 30.3% [508]). Pregnancy per AI did not differ between OVS and OVS + CIDR cows regardless of CL status. Short synch is an alternative to the entire modified Ovsynch program to produce similar P/AI when the CL status was detected accurately, and regardless of functional CL status, SS reduced inter-insemination intervals by 7 d.

Predicting the probability of conception in dairy cows with clinical endometritis based on a combination of anamnestic information and examination results

The objective of this study was to improve prediction of the probability of conception in dairy cows with clinical endometritis by means of a combination of examination results. For this purpose, a total of 1386 dairy cows were screened for clinical endometritis and data from 286 cows were collected including the calving history, puerperal or concurrent diseases and cow-specific data (breed, parity, BCS at puerperal control 1 (PC 1 = 22-45 days in milk (DIM)), and daily milk yield). The diagnosis of clinical endometritis was made at PC 1 by vaginal discharge scoring with a Metricheck device on a scale from 1 to 3 (endometritis score (ES) 1 to 3). A detailed clinical and gynecological examination including external inspection, transrectal palpation and ultrasonographic examination of the genital tract (cervix, uterus, and ovaries), vaginoscopy and microbiological analysis of the intrauterine content were performed. All cows with clinical endometritis (n = 286) were treated according to the ovarian findings (corpus luteum, dominant follicle) at PC 1. A second puerperal control was performed 21 ± 1 days later. Data was collected until 200 DIM. The risk factors for ES 3 and their effect on the distribution of ES were determined by the Chi-square test and binary logistic regression. Multivariable implications of a large sum of examination parameters on the pregnancy outcome at different DIM (100, 150 and 200 DIM) were analyzed on the basis of conditional inference trees. The prevalence of clinical endometritis was 28%. The ovarian findings at PC 1 did not have any impact on reproductive performance. Puerperal diseases prior to the study, visible vaginal discharge (VVD) and the presence of Trueperella pyogenes (TP) were associated with an ES 3. The prediction of pregnancy status for all DIM times was dominated significantly by VVD or TP as decisive factors. Cows with VVD or TP had lower conception rates at all DIM times than cows without these findings, but the predictive accuracy was similar for both groups. These results suggest that VVD is a valuable and practical examination parameter, which can be used for pregnancy prediction on farm. Therefore, it might facilitate early breeding decisions in cows with clinical endometritis under farm conditions.

Absence of a corpus luteum and relatively lesser concentrations of progesterone during the period of pre-ovulatory follicle emergence results in lesser pregnancy rates in Bos indicus cattle

Concentrations of progesterone before AI have had variable effects on fertility in both Bos indicus and Bos taurus cattle. The aim of this study was to determine if fertility and concentrations of progesterone after AI were affected in Bos indicus females when pre-ovulatory follicles develop in the absence or presence of a corpus luteum (CL). Between 6.5-7.5 days after a synchronised oestrus, all follicles ≥4 mm in diameter were aspirated (Day 0) and cloprostenol was administered on Days 0 and 1 (LP4, n = 36) or on Days 4 and 5 (HP4, n = 40). Animals were inseminated on detection of oestrus until Day 9. Breeding continued using natural mating between Days 9 and 19, AI on detection of oestrus between Day 19 and 29 and natural mating between Days 29-90. Mean concentrations of progesterone were less on Days 2-4 in the LP4 compared to the HP4-treated animals but similar on Days 14 and 20. In the LP4- compared to the HP4-treated animals, the odds of being detected in oestrus and ovulating close to the first AI were similar, but odds of pregnancy to first AI (OR = 0.19, 95% CI 0.07 - 0.52) and after 1, 4 and 13 weeks of breeding were less (P ≤  0.051). Absence of a CL and relatively lesser concentrations of progesterone during emergence of pre-ovulatory follicles resulted in lesser pregnancy rates to AI in Bos indicus cattle but did not affect concentrations of P4 after ovulation.

Change of daily milk yield during estrous period in Holstein cattle raised under Mediterranean climate

This study was conducted to determine the effect of estrus on the daily milk yield in Holstein cows and to investigate the chance of using the possible milk yield changes in determining the estrus. During the 3-year period of the study, 103 dairy cows were observed 4 days before and 4 days after daily milk yield of 240 estruses and a total of 2174 daily milk yields were evaluated. Variance analysis was used to determine the factors affecting the daily milk yield, and the LSD test was used for multiple comparisons. Insemination year, insemination season, number of lactation, milk yield group, and daily milk yield of lactation period were found to be significant (P < 0.01). On the other hand, the effect of estrus days on milk yield was insignificant. In the days of estrus, the least square mean of milk yield is 31.0 kg, while the lowest and highest milk yields are 10.2 kg and 62.9 kg. The daily milk yield in the estruses decreased by an average of 300 g, which decreased to 400 g by continuing 1 day after the estruses. The next day, however, it increased rapidly by 600 g, and then dropped again, probably due to the effect of metestrus. It was found that, among all estruses, 31.3% of cows decreased their milk yield, whereas 26.5% of cows increased their milk yield. However, 42.2% of cows both decreased and increased their milk yield in different estruses. The interval between birth and the first insemination after were found to be longer (97.5 days and 92.9 days) at high milk-yielding cows compared to the low milk-yielding cows. According to the results of this study, daily milk yield changes could not be used as an estrus indicator.

Impacts of chronic and increasing lipopolysaccharide exposure on production and reproductive parameters in lactating Holstein dairy cows

Lipopolysaccharide (LPS) administration causes immunoactivation, which negatively affects production and fertility, but experimental exposure via an acute bolus is unlikely to resemble natural infections. Thus, the objectives were to characterize effects of chronic endotoxemia on production parameters and follicular development in estrous-synchronized lactating cows. Eleven Holstein cows (169 ± 20 d in milk; 681 ± 16 kg of body weight) were acclimated to their environmental surroundings for 3 d and then enrolled in 2 experimental periods (P). During P1 (3 d) cows consumed feed ad libitum and baseline samples were obtained. During P2 (7 d), cows were assigned to continuous infusion of either (1) saline-infused and pair-fed (CON-PF; 40 mL/h of saline i.v.; n = 5) or (2) LPS infused and ad libitum fed (LPS-AL; Escherichia coli O55:B5; 0.017, 0.020, 0.026, 0.036, 0.055, 0.088, and 0.148 μg/kg of body weight/h i.v. on d 1 to 7, respectively; n = 6). Controls were pair-fed to the LPS-AL group to eliminate confounding effects of dissimilar nutrient intake. Infusing LPS temporally caused mild hyperthermia on d 1 to 3 (+0.49°C) relative to baseline. Dry matter intake of LPS-AL cows decreased (28%) on d 1 of P2, then progressively returned to baseline. Relative to baseline, milk yield from LPS-AL cows was decreased on d 1 of P2 (12%). No treatment differences were observed in milk yield during P2. Follicular growth, dominant follicle size, serum progesterone (P4), and follicular P4 and 17β-estradiol concentrations were similar between treatments. Serum 17β-estradiol tended to increase (115%) and serum amyloid A and LPS-binding protein were increased (118 and 40%, respectively) in LPS-AL relative to CON-PF cows. Compared with CON-PF, neutrophils in LPS-AL cows were initially increased (45%), then gradually decreased. In contrast, monocytes were initially decreased (40%) and progressively increased with time in the LPS-AL cows. Hepatic mRNA abundance of cytochrome P450 family 2 subfamily C (CYP2C) or CYP3A was not affected by LPS, nor was there a treatment effect on toll-like receptor 4 or LBP; however, acyloxyacyl hydrolase and RELA subunit of nuclear factor kappa B tended to be increased in LPS-AL cows. These data suggest lactating dairy cows become tolerant to chronic and exponentially increasing LPS infusion in terms of production and reproductive parameters.

Uterine Involution and Ovarian Activity in Postpartum Holstein Dairy Cows. A Review

Following parturition in the cow, there is a significant period of sexual quiescence of variable length. This period of reproductive quiescence was found to be longer in suckling or intensively milked animals.This acyclic period is generally considered as the postpartum anoestrous period. The postpartum period constitutes an important period in the reproductive life of dairy cows because of its enormous influence upon subsequent fertility. The entire postpartum period, puerperium, is defined as the period from parturition until the genital organs return to its normal physiological and histological condition, as in normal non-gravid state. They added that any extension of the puerperium in cows might have a detrimental effect on the reproductive performance of the individual animal. Thus, the main determinant of this period is essentially dependent on the resumption of normal ovarian cycles, the manifestation of estrus behaviour and conception following insemination.

Level of circulating concentrations of progesterone during ovulatory follicle development affects timing of pregnancy loss in lactating dairy cows

The objective of this experiment was to determine the effect of high versus low progesterone (P4) during the pre-dominance or dominance phase (or both) of ovulatory follicle development on follicular dynamics and fertility of lactating dairy cows. Progesterone (P4) was manipulated to reach high (H) or low (L) serum concentrations during the pre-dominance phase (d 0 to 4 of the wave) and dominance phase (d 5 to 7 of the wave) of a second follicular wave ovulatory follicle, creating 4 treatments: H/H, H/L, L/H, and L/L. Luteolysis was induced with PGF_2α on d 7 of the wave and ovulation was induced with GnRH 56 h after PGF_2α. Cows (n = 558) received artificial insemination (AI) 16 h following GnRH. Pregnancy was determined at 6 intervals during gestation and at calving to quantify pregnancy loss beginning at d 23 post-AI utilizing pregnancy-specific protein B (PSPB) in novel within-cow comparisons. Cows with single ovulations assigned to the L/L treatment had greater pre-ovulatory follicle diameter compared with cows assigned to the L/H or H/L treatments. Cows with single ovulations had greater pre-ovulatory follicle diameter compared with cows with double ovulations. Low P4 in H/L, L/H, and L/L increased double ovulation rate compared with H/H. Cows with double ovulations had greater pregnancies per AI (P/AI) on d 23 post-AI compared with cows with single ovulations but had greater losses if ovulations were unilateral. Cows with low P4 during the entire period of the ovulatory follicle development also had greater P/AI on d 23 post-AI compared with cows with high P4 during both phases. However, full-term P/AI was not different between treatments. This was a result of the greater incidence of pregnancy losses between d 35 and 56 of gestation for cows with unilateral double ovulations compared with bilateral double ovulations and single ovulatory cows. Cows with single ovulation and low circulating P4 during the dominance period of follicle development had increased pregnancy losses between d 35 and 56 of gestation compared with cows with single ovulations and high P4. The PSPB measurements on d 16 and 23 post-AI were highly accurate in the prediction of pregnancy at d 28. The PSPB differed on d 23 and 28 between cows that had versus cows that did not have pregnancy losses between d 28 and 35 of gestation. In summary, circulating concentrations of P4 during ovulatory follicle development affected numbers of follicles ovulated and timing of subsequent pregnancy losses.

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.

Dairy cow breed interacts with stocking rate in temperate pasture-based dairy production systems

Economic optimum stocking rates for grazing dairy systems have been defined by accounting for the pasture production potential of the farm [t of dry matter (DM)/ha], the amount of feed imported from outside the farm (t of DM/ha), and the size of the cow (kg). These variables were combined into the comparative stocking rate [CSR; kg of body weight (BW)/t of feed DM available] measure. However, CSR assumes no effect of cow genetics beyond BW, and there is increasing evidence of within-breed differences in residual feed intake and between-breed differences in the gross efficiency with which cows use metabolizable energy for milk production. A multiyear production system experiment was established to determine whether Jersey (J) and Holstein-Friesian (HF) breeds performed similarly at the same CSR. Fifty-nine J cows and 51 HF cows were randomly allocated to 1 of 2 CSR in a 2 × 2 factorial arrangement; systems were designed to have a CSR of either 80 or 100 kg of BW/t of feed DM (J-CSR80, J-CSR100, HF-CSR80, and HF-CSR100 treatment groups). Data were analyzed for consistency of farmlet response over years using ANOVA procedures, with year and farmlet as fixed effects and the interaction of farmlet with year as a random effect. The collated biological data and financial data extracted from a national economic database were used to model the financial performance for the different breed and CSR treatments. On average, annual and individual season pasture DM production was greater for the J farmlets and was less in the CSR100 treatment; however, the effect of CSR was primarily driven by a large decline in pasture DM production in the HF-CSR100 treatment (breed × CSR interaction). This interaction in feed availability resulted in a breed × CSR interaction for the per-cow and per-hectare milk production variables, with HF cows producing more milk and milk components per cow in the CSR80 treatment but the same amount as the J cows in the CSR100 treatment. On a per-hectare basis, HF cows produced the same amount of 4% fat-corrected milk and lactose as J cows in the CSR80 treatment, but less fat; at CSR100, J cows produced more 4% fat-corrected milk, fat, and protein per hectare than HF cows. Our results support a greater gross efficiency for use of metabolizable energy by the J cow; 11% less total metabolizable energy was required to produce 1 kg of fat and protein at a system level. Economic modeling indicated that profitability of both breeds was less at CSR100, but the decline in profitability with increasing stocking rate was much greater in the HF breed. Holstein-Friesian cows were more profitable at CSR80 but were less profitable at CSR100.

A review of oestrous behaviour and detection in dairy cows

A number of measurable physiological events characteristically occur and cause changes during the perioestrual period including the classical, diagnostic sign of standing behaviour. The onset of oestrus coincides with peak titres of oestradiol-17β that subsequently induce the preovulatory surge of LH within 1 to 3 h and ovulation of a mature follicle some 24 to 32 h after the onset of oestrus. Although detection efficiencies are consistently greater in higher producing herds, oestrus-detection efficiency generally has declined in recent years as herd size and milk production have increased. New technologies have introduced some needed assistance for detecting cows in oestrus. These include various in expensive heat mount detectors to more sophisticated electronic gadgetry, such aspedometry and radiotelemetric sensors that detect temperature, tissue impedance, and pressure. Oestrus detection aids are usually more efficient but not necessarily more accurate than visual observation. Differences in housing and environmental conditions, in addition to labor inputs, costs, and efficacies, result in variable acceptance of such technologies. Detection efficiency and accuracy can be improved by simultaneous use of synergistic technologies; those that compliment each other and monitor different indicators of oestrus. Combining technologies for simultaneous measurements of several physiological events associated specifically with the onset of oestrus and their radiotelemetrically signaling to a central computer for subsequent analysis should provide greater efficiency ofoestrus detection with fewer false positives. The ultimate goal of determining the onset of oestrus or ovulation is to predict the optimal timing for insemination. Ultimately, herd personnel must interpret information gathered by these technologies and judge whether or not and when to inseminate cows based on their visual inspection of identified cows.

Pregnancy losses in cattle: potential for improvement

For heifers, beef and moderate-yielding dairy cows, it appears that the fertilisation rate generally lies between 90% and 100%. For high-producing dairy cows, there is a less substantive body of literature, but it would appear that the fertilisation rate is somewhat lower and possibly more variable. In cattle, the major component of embryo loss occurs in the first 16 days following breeding (Day 0), with emerging evidence of greater losses before Day 8 in high-producing dairy cows. In cattle, late embryo mortality causes serious economic losses because it is often recognised too late to rebreed females. Systemic concentrations of progesterone during both the cycle preceding and following insemination affect embryo survival, with evidence of either excessive or insufficient concentrations being negatively associated with survival rate. The application of direct progesterone supplementation or treatments to increase endogenous output of progesterone to increase embryo survival cannot be recommended at this time. Energy balance and dry matter intake during the first 4 weeks after calving are critically important in determining pregnancies per AI when cows are inseminated at 70-100 days after calving. Level of concentrate supplementation of cows at pasture during the breeding period has minimal effects on conception rates, although sudden reductions in dietary intake should be avoided. For all systems of milk production, more balanced breeding strategies with greater emphasis on fertility and feed intake and/or energy must be developed. There is genetic variability within the Holstein breed for fertility traits, which can be exploited. Genomic technology will not only provide scientists with an improved understanding of the underlying biological processes involved in fertilisation and the establishment of pregnancy, but also, in the future, could identify genes responsible for improved embryo survival. Such information could be incorporated into breeding objectives in order to increase the rate of genetic progress for embryo survival. In addition, there is a range of easily adoptable management factors, under producer control, that can either directly increase embryo survival or ameliorate the consequences of low embryo survival rates. The correction of minor deficits in several areas can have a substantial cumulative positive effect on herd reproductive performance.

Reproductive performance in Holstein-Friesian cows in relation to genetic merit and level of feeding when grazing pasture

One hundred and eight Holstein-Friesian cows in six herds were run on six separate farmlets over a 5-year period from 1995 to 1999 at Wollongbar Agricultural Institute, on the subtropical north coast of New South Wales, Australia. Three of the herds comprised high genetic merit (HGM) cows — Australian breeding value (ABV) of +49·1 kg for milk fat (F) plus protein (Pr) and three herds comprised low genetic merit (LGM) cows-ABV of 2·3 kg. Within genetic merit groupings, one herd was given 0·34 t (l), one herd was given 0·84 t (m) and one herd 1·71 t (h), of concentrate per cow per lactation. Within each genetic merit group, cows were matched for milk yield and live weight, and over all groups for time of calving and age at the commencement of the study. The 30 paddocks within each farmlet were matched between farmlets for pasture type and pasture growth rate and soil fertility. Half the cows within each herd calved over a 3-month period in spring and the other half in autumn. Strict management criteria ensured that there was no bias towards particular treatment groups.

HGM cows were ‘open’ (days from calving to conception) for 8 days longer than the LGM cows (99 v. 91 days). The lHGM cows took 11 days longer to commence luteal phase activity and 21 days longer to first observed oestrus post calving than hLGM cows (P < 0·001), with the other groups being intermediate.

After 24 days of mating, 22% of lHGM cows were pregnant, and this was less than half of the rate of the best herd-mLGM. After 9 weeks of mating, the chances of an LGM cow being pregnant was 87% greater than an HGM cow. After 12 weeks of mating, 70% of lHGM cows were pregnant compared with a mean pregnancy rate of 87% for the LGM cows.

The number of cows treated for abnormal ovarian activity (anoestrus, cystic) was highest (P < 0·001) in the HGM herds given ‘l’ and ‘m’ levels of concentrate compared with the remaining herds (0·24 v. 0·12 treatments per cow mated, respectively).

There was a significant positive relationship between live-weight change from 4 weeks before, to the start of, the mating period and the chances of a cow being pregnant at 24 days (P < 0·05) and at 6 and 9 weeks after the commencement of mating.

There was a significant negative relationship (P < 0·001) between the change in daily F plus Pr yield, from the start to 4 weeks after mating began, and pregnancy rate at 9 weeks. The change in F plus Pr yield was +63 g/day for cows pregnant at nine weeks as opposed to +154 g/day for cows not pregnant.

The results of the present study indicate that the reproductive performance of HGM cows, with a mean of 61% North American (NA) genes, is lower than LGM cows (22% NA genes) under a predominantly pasture-based system of farming. The influence on reproduction was possibly due to genes favouring partitioning of energy to milk yield rather than body-condition maintenance in the HGM cows and when food intake was inadequate, then being more willing to use body reserves.

These reproductive problems may be reduced by more intensive reproductive management. However, such practices are costly and time consuming. Another approach may be to ensure that live-weight loss over the mating period is minimized by strategic supplementary feeding.

Declining fertility in dairy cattle: changes in traditional and endocrine parameters of fertility

Reproductive performance of 714 Holstein Friesian dairy cows was monitored between October 1995 and June 1998 using thrice weekly milk progesterone determinations. Defined endocrine parameters such as interval topost-partumcommencement of luteal activity, inter-ovulatory interval and length of luteal and inter-luteal intervals were used with a number of traditional measures of reproductive performance to investigate the current status of fertility in a sample of United Kingdom dairy herds. A comparison of the results of the 1995 to 1998 trial with those of a previous (1975 to 1982) milk progesterone database, which included 2503 lactations in British Friesian cows monitored using a similar milk sampling protocol, revealed a decline infertility between these periods.

Between 1975-1982 and 1995-1998, pregnancy rate to first service declined from 55·6% to 39·7% (P< 0·001), at a derived average rate approaching 1% per year. This decline was associated with an increase (P< 0·001) in the proportion of animals with one or more atypical ovarian hormone patterns from 32% to 44%. There was a significant (P< 0·001) increase in the incidence of delayed luteolysis during the first cyclepost partum(delayed luteolysis type I; 7·3% to 18·2%) and during subsequent cycles (delayed luteolysis type II; 6·4% to 16·8%), although the incidence of prolonged anovulation post partům (delayed ovulation type I; 10·9% to 12·9%) and prolonged inter-luteal intervals (delayed ovulation type II; 12·9% to 10·6%) did not alter significantly. These changes resulted in an increase in mean luteal phase length from 12·9 (s.e. 0·09) to 14·8 (s.e. 0·17) days and an increase in inter-ovulatory interval from 20·2 (s.e. 0·1) to 22·3 (s.e. 0·2) days. The decline infertility was also reflected in traditional measures of fertility since although interval to first service remained relatively unchanged (74·0 (s.e. 0·4) to 77·6 (s.e. 1·1) days) calving interval lengthened from 370 (s.e. 2·2) to 390 (s.e. 2·5) days. Collectively these changes may have contributed to the decline in pregnancy rates observed over the last 20 years.

Effect of manipulating progesterone before timed artificial insemination on reproductive and endocrine parameters in seasonal-calving, pasture-based Holstein-Friesian cows

Fertility to timed AI (TAI) is profoundly affected by progesterone (P4) levels during hormonal synchronization protocols. Holstein-Friesian dairy cows managed in a seasonal-calving, pasture-based production system were randomly assigned to 2 treatments to manipulate P4 before TAI during growth of the preovulatory follicle. Cows in the first treatment (High P4; n=30) were submitted to a Double-Ovsynch protocol {Pre-Ovsynch [GnRH; 7 d, PGF2α; 3 d, GnRH] followed 7 d later by Breeding-Ovsynch [GnRH (G1); 7 d PGF2α; 24 h, PGF2α; 32 h, GnRH (G2); 16 h, TAI]}. Cows in the second treatment (n=30; Low P4) received the same Double-Ovsynch protocol but with an additional PGF2α treatment 24 h after G1. Overall, synchronization rate did not differ between treatments and was 92% (55/60). Unexpectedly, 37% of Low P4 cows were detected in estrus ~24 h before scheduled TAI and were inseminated ~16 h before scheduled TAI. Overall, P4 did not differ between treatments at G1, whereas High P4 cows had greater P4 concentrations at PGF2α and G2 than Low P4 cows. High P4 cows had the smallest mean follicle diameter at G2, whereas Low P4 cows with no estrus before TAI had intermediate mean follicle diameter at G2, and Low P4 cows with estrus before TAI had the largest mean follicle diameter. Low P4 cows with estrus before TAI had larger corpora lutea 15 d after TAI than Low P4 cows without estrus before TAI or High P4 cows. In accordance with corpus luteum size on d 15, High P4 cows and Low P4 cows without estrus before TAI had lower P4 from 4 to 46 d after TAI than Low P4 cows with estrus before TAI. Relative mRNA levels of the interferon-stimulated genes ISG15, MX1, MX2, and OAS1 were greater for Low P4 than for High P4 cows, whereas relative mRNA levels of RTP4 were greater for High P4 than for Low P4 cows 18 d after TAI. Treatment did not affect plasma pregnancy-associated glycoprotein concentrations after TAI; however, pregnancy-associated glycoprotein concentrations were affected by pregnancy status and parity. Treatment did not affect pregnancy per artificial insemination at 29, 39, or 60 d after TAI, and no pregnancy losses were observed from 39 to 60 d after TAI. We concluded that (1) Low P4 cows were more likely to express estrus than High P4 cows; (2) the subpopulation of Low P4 cows that expressed estrus had larger preovulatory follicles and greater P4 concentrations after TAI; and (3) regardless of estrus before TAI, all Low P4 cows had greater mRNA expression for 5 of 6 interferon-stimulated genes than High P4 cows 18 d after TAI.

Ultrasonographic Doppler Use for Female Reproduction Management

Transrectal color Doppler ultrasonography is a useful technique to get new information about physiologic and pathophysiologic alterations of the uterus and ovaries in female cattle. During all reproductive stages characteristic changes in uterine blood flow are observed. Cows with puerperal disturbances show delayed decrease in uterine blood flow in the first few weeks postparturition compared with healthy cows. Measurement of follicular blood flow is used to identify normally developing follicles and predict superovulatory response. Determination of luteal blood is more reliable than B-mode sonography to distinguish between functional and nonfunctional corpora lutea. Color Doppler ultrasonography is a promising tool to improve reproductive management in female cattle.

Pregnancy rate in dairy cows treated with progesterone for six days during estrus synchronization with PGF2α

The present study evaluated the effect of progesterone supplementation during a double PGF2α injection synchronization protocol on pregnancy per artificial insemination (P/AI) and on the incidence of twin births. Seven hundred and eighty three dairy cows were synchronized with two injections of PGF2α 14 days apart, starting on day 35 postpartum for their first postpartum insemination. Six days before the second PGF2α injection, cows were treated either with a progesterone-releasing intravaginal device (PRID-Delta) and an intramuscular injection of 500mg of progesterone (n=387) or served as control (n=396) and did not receive progesterone treatment. Cows were inseminated 12h after being detected in estrus. Pregnancy was diagnosed 40-45 days later by transrectal palpation. Progesterone administration improved (P<0.05) the percentage of cows detected in estrus in multiparous [(192/255) 75% vs (161/267) 60%], but not in primiparous cows [93/132 (70%) vs 90/129 (70%)]. Progesterone treatment increased P/AI in multiparous [53/192 (28%) vs 27/161 (17%)] but not in primiparous cows [25/93 (27%) vs 29/90 (32%)]. The incidence of twin births tended to be lower (P=0.09) in cows treated with progesterone [1/74 (1%)] than in the control group [4/53 (7%)]. It is concluded that progesterone administration during estrus synchronization with two PGF2α injections in dairy cows improves estral response and increases P/AI in multiparous, but not in primiparous cows, and tended to decrease the incidence of twin births.

Effect of Lipopolysaccharide on Progesterone Production during Luteinization of Granulosa and Theca cells In Vitro

The aim of this study is to examine the effect of lipopolysaccharide (LPS) on progesterone production during luteinization of granulosa and theca cells isolated from bovine large follicles. Granulosa and theca cells isolated from large follicles of bovine ovaries were exposed to LPS under appropriate hormone conditions in vitro. Progesterone (P4) production in theca cells, but not granulosa cells, was decreased by long-term exposure of LPS. Long-term exposure of LPS suppressed the gene expression of luteinizing hormone receptor in theca cells. Although long-term exposure of LPS did not affect the expression of steroidogenic acute regulatory protein (StAR) and 3β-hydroxy-steroid dehydrogenase (3β-HSD) genes, it did inhibit the protein expression of StAR and 3β-HSD in theca cells. These findings suggest that theca cells, rather than granulosa cells, are susceptible to LPS during luteinization and that LPS inhibits P4 production by decreasing protein levels of StAR during luteinization of theca cells.

The effect of puerperal uterine disease on histopathologic findings and mRNA expression of proinflammatory cytokines of the endometrium in dairy cows

The aim of this study was to investigate the effect of puerperal uterine disease on histopathologic findings and gene expression of proinflammatory cytokines in the endometrium of postpuerperal dairy cows; 49 lactating Holstein-Friesian cows were divided into two groups, one without (UD-; n = 29) and one with uterine disease (UD+; n = 21), defined as retained fetal membranes and/or clinical metritis. General clinical examination, vaginoscopy, transrectal palpation, and transrectal B-mode sonography were conducted on days 8, 11, 18, and 25 and then every 10 days until Day 65 (Day 0 = day of calving). The first endometrial sampling (ES1; swab and biopsy) was done during estrus around Day 42 and the second endometrial sampling (ES2) during the estrus after synchronization (cloprostenol between days 55 and 60 and GnRH 2 days later). The prevalence of histopathologic evidence of endometritis, according to the categories used here, and positive bacteriologic cultures was not affected by group (P > 0.05), but cows with uterine disease had a higher prevalence of chronic purulent endometritis (ES1; P = 0.07) and angiosclerosis (ES2; P ≤ 0.05) than healthy cows. Endometrial gene expression of IL1α (ES2), IL1β (ES2), and TNFα (ES1 and ES2) was higher (P ≤ 0.05) in the UD+ group than in the UD- group. In conclusion, puerperal uterine disease had an effect on histopathologic parameters and on gene expression of proinflammatory cytokines in the endometrium of postpuerperal cows, indicating impaired clearance of uterine inflammation in cows with puerperal uterine disease.

The effect of metritis and subclinical hypocalcemia on uterine involution in dairy cows evaluated by sonomicrometry

The objective of this study was to examine the effects of metritis and subclinical hypocalcemia on reduction of uterine size in dairy cows using ultrasonography and sonomicrometry. Four piezoelectric crystals were implanted via laparotomy into the myometrium of the pregnant uterine horn of 12 pluriparous Holstein Friesian cows 3 weeks before the calculated calving date. Sonometric measurements were conducted daily from 2 days before parturition (= Day 0) until Day 14 after calving and then every other day until Day 28. Distances between adjacent crystals were expressed in relation to reference values obtained before calving. The diameter of the formerly pregnant uterine horn was measured using transrectal B-Mode sonography starting on Day 10. Cows were retrospectively divided into the following groups: cows without metritis (M-; n = 7), cows with metritis (M+; n = 5), cows with normocalcemia (SH-; Ca > 2.0 mmol/l on Days 1 to 3; n = 5) and cows with subclinical hypocalcemia (SH+; Ca < 2.0 mmol/l in at least one sample between Days 1 and 3; n = 7). Metritis did not affect (P > 0.05) sonometric measurements, but the diameter of the formerly pregnant horn was larger (P ≤ 0.05) between Days 15 and 21 in M+ cows than in M‒ cows. Reduction in uterine length in hypocalcemic cows was delayed (P ≤ 0.05) between Days 8 and 21 compared with normocalcemic cows, but the uterine horn diameter was not related to calcium status. In conclusion, both diseases affected reduction of uterine size until Day 28. Cows with metritis had a larger uterine diameter, possibly attributable to accumulation of lochia, and cows with subclinical hypocalcemia had delayed reduction of uterine length, presumably related to reduction of myometrial contractility.

Intravaginally administered lactic acid bacteria expedited uterine involution and modulated hormonal profiles of transition dairy cows

The objective of this investigation was to evaluate whether intravaginal infusion of lactic acid bacteria (LAB) around parturition could expedite involution rate of the uterus and improve reproductive performance of postpartum dairy cows. One hundred pregnant Holstein dairy cows were assigned to 1 of 3 experimental groups: (1) 1 dose of LAB in wk -2 and -1 and 1 dose of carrier in wk 1 relative to the expected day of parturition (TRT1); (2) 1 dose of LAB in wk -2, -1, and 1 (TRT2); and (3) 1 dose of carrier in wk -2, -1, and 1 (CTR). The LAB treatment was a lyophilized mixture of Lactobacillus sakei FUA3089, Pediococcus acidilactici FUA3138, and Pediococcus acidilactici FUA3140 with a cell count of 10(8) to 10(9) cfu/dose. Uterine involution and ovarian activity was evaluated by transrectal ultrasonography weekly from d 7 to 49 postpartum. Blood samples were collected from a subset of cows to quantify prostaglandin (PG) F2α metabolite (PGFM), PGE2, and progesterone. Cows treated with LAB had smaller cross-sectional areas of gravid horn and uterine body on d 14 postpartum. Cows in TRT2 resumed ovarian cyclicity earlier, as indicated by increased concentrations of serum progesterone. Cows in TRT1 had fewer days open than those in the CTR (110 vs. 150 d), whereas cows in TRT2 and CTR did not differ in days open. In addition, both TRT1 and TRT2 increased the concentrations of PGFM at calving week, and cows in TRT2 also had greater concentrations of PGE2 on d 14 and d 21 postpartum relative to CTR. Overall, cows treated intravaginally with LAB had smaller gravid horn and uterine body on d 14 postpartum than those in the CTR group. Treatment with LAB also increased concentrations of serum PGFM (3,533±328pg/mL in TRT1, 4,470±372pg/mL in TRT2, and 2,000±328pg/mL in CTR on d 0, respectively), with the TRT1 group having fewer cows that resumed ovarian cyclicity but fewer days open compared with both TRT2 and CTR groups. More research is warranted to better understand the mechanism(s) by which intravaginal LAB expedited uterine involution and affected hormonal profiles.

Perfil de progesterona em novilhas com diferente atividade luteal e tratadas com implantes vaginais

O dispositivo de liberação de progesterona (DLP) é muito importante em protocolos de Inseminação Artificial em Tempo Fixo (IATF). Representa cerca de 43% dos custos e é objeto de estudos sobre a eficiência da sua reutilização. No entanto, perfis de liberação de progesterona (P4) em animais com diferentes concentrações endógenas desse esteroide não são claramente descritos. Este estudo teve como objetivo avaliar a concentração sérica de P4 em fêmeas com diferentes situações de atividade luteal, tratadas com DLP novo (1g de P4) por 8 dias. Trinta novilhas mestiças cíclicas foram divididas em três grupos: em G1 e G2, o DLP foi inserido (D0) sete dias após a ovulação induzida. Adicionalmente, 0,15mg de D-cloprostenol foi administrado três dias depois para promover a luteólise em G2. Para G3, o corpo lúteo foi lisado antes da inserção do DLP para que a P4 exógena fosse a única fonte desse hormônio. O sangue foi coletado no D0, D3, D5 e D8, e a P4 avaliada por RIA. Médias de P4 foram comparadas entre os grupos em cada dia e dentro do grupo, entre os dias, utilizando o teste Tukey. Antes da inserção do implante (D0), os níveis de P4 foram, nos grupos, semelhantes em G1 e G2, e superiores a G3 (5,3±3,1a e 5,3±1,4avs 0,6±0.3bng/mL, respectivamente-P<0,05). No D3, ocorreu o mesmo perfil (5,7±2,6a e 5,4±2,0a e 3,6±0.8bng/mL, respectivamente para G1 e G2 vs G3, P<0,05). Trinta e seis horas (D5) após a PGF, a P4 no G2 caiu para níveis semelhantes aos do grupo G3 e ambos diferiram (P<0,05) de G1 (3,3±1,6b vs 2,4±0,9b e 2,1±0.7bng/mL). Essa diferença se manteve (P<0,05) em D8 (3,1±1,3a, 1,8±0,8b e 1,6±0.6b ng/mL). O aumento da P4 após a inserção (D3 - D0) foi maior (P<0,05) em G3 que em G1 e G2 (2,8±0,9a vs 0,4±1,8b e 0,2±1.4bng/mL). Os animais com maior P4 endógena levam a menor liberação de P4 exógena a partir do DLP. Portanto, os níveis remanescentes de P4 no DLP após o uso dependem da concentração endógena de P4 do animal e possíveis alterações durante a permanência.

Effect of progesterone supplementation on fertility responses of lactating dairy cows with corpus luteum at the initiation of the Ovsynch protocol

The objectives of this study were to determine the effects of supplemental progesterone on fertility responses of lactating dairy cows with a CL at the initiation of the timed artificial insemination (AI) program. Holstein cows were subjected to the Ovsynch protocol (Day -10 GnRH, Day -3 PGF2α, Day -0.7 GnRH, and Day 0 timed AI). Ovaries were scanned by ultrasonography on Day -10 and cows with CL were blocked by pen and assigned randomly to receive no supplemental progesterone (control, n = 863) or to receive a controlled internal drug-release (CIDR) insert containing progesterone from Days -10 to -3 (1CIDR, n = 862). Cows were observed for signs of estrus beginning on Day -9 based on removal of tail chalk and those in estrus received AI on the same day. Blood sampled from a subset of cows was analyzed for progesterone concentrations on Days -10, -9, -7, -5, -3, 0, 6, 13, and 19. Pregnancy was diagnosed on Days 32 and 60 after AI. Supplementation increased (P < 0.01) progesterone concentrations between Day -9 and -3 compared with control (7.5 vs. 6.2 ng/mL). Treatment had no effect on the ovulatory response to the first and final GnRH injections of the Ovsynch protocol, the proportion of cows that maintained their CL until the day of PGF2α injection, or the diameter of the ovulatory follicle before AI. Although the overall proportion of cows in estrus at AI did not differ between treatments, progesterone supplementation prevented (P < 0.01) cows from coming into estrus from Days -9 to -3 (0.0% vs. 4.7%), whereas it increased (P = 0.02) the proportion of cows inseminated in estrus from Days -2 to -1 (7.1% vs. 4.5%). Pregnancy per AI (P/AI) tended to be reduced (P = 0.06) by supplemental progesterone on Day 32 (40.5% vs. 45.0%), but not on Day 60 after AI (36.6% vs. 39.7%). A tendency for an interaction (P = 0.09) between treatment and the presence of CL at the PGF2α injection was observed for P/AI on Day 32 in cows that received timed AI because progesterone supplementation reduced P/AI in cows that maintained their CL until Day -3 (40.3% vs. 46.7%); however, it increased P/AI in those that did not have a CL at PGF2α (38.1% vs. 27.7%). Treatment did not affect pregnancy loss between Days 32 and 60 of gestation. In conclusion, incorporating a single intravaginal insert to the timed AI program increased progesterone concentrations in plasma by 1.3 ng/mL, but did not benefit fertility in dairy cows that have CL at the initiation of the synchronization protocol.