Symposium review: The impact of absorbed nutrients on energy partitioning throughout lactation

Lactational performance of dairy cows fed diets based on corn silages varying in ruminal degradability of starch and fiber

Corn silage (CS) is a cornerstone component in dairy cattle diets, contributing up to 50% of the total dietary NEL intake. Selecting high-quality CS hybrids is critical for improving production efficiency and reducing the carbon footprint of dairy operations. The rumen fermentable organic matter index (RFOMI) assesses CS nutritional quality, with a focus on rumen fermentable NDF (RFNDF) and starch (RFST), which together account for the majority of digestible silage OM. The objective was to evaluate the effects of feeding CS with similar RFOMI but varying RFST and RFNDF contents on lactational performance, enteric gas emissions, nutrient digestibility, and nitrogen utilization in dairy cows. Rumen fermentable NDF and RFST were determined using established in vitro and in situ methods, incorporating digestibility coefficients and nutrient fraction analyses. A total of 48 mid-lactation Holstein cows (16 primiparous, 32 multiparous) were used in this study. Post-ensiling RFST to RFNDF ratios (RFST:RFNDF) in CS were used for treatment designation. The study was a randomized complete block design where cows within a block were randomly assigned to treatment diets. The diets were fed as TMR and contained 50% CS (dietary DM basis) with RFST:RFNDF of 1.62, 1.85, 1.92, or 2.08. Animal performance and enteric gas emissions were evaluated using polynomial linear or quadratic effects of postfermentation CS RFST:RFNDF ratios. A quadratic effect of treatment on DMI was observed, where cows fed CS with the lowest RFST:RFNDF ratio resulted in the greatest DMI. Dairy cows fed CS with an increasing RFST:RFNDF ratio tended to have increased milk yield, but no effects were observed on ECM yield. Increasing RFST:RFNDF of CS in the diet increased quadratically feed and ECM feed efficiencies, CH4 emission yield (as g/kg DMI), and total-tract DM and OM digestibilities. These results indicated that feeding CS with RFST:RFNDF ratios within 1.85 to 1.92, when compared with CS hybrids outside that range of RFST: RFNDF, at 50% of dietary DM, may promote a reduction in DMI but increase feed and ECM feed efficiencies andCH4 yield by enhancing apparent total-tract DM digestibility in lactating dairy cows.

Effects of Postpartal Relative Body Weight Change on Production Performance, Serum Biomarkers, and Fecal Microbiota in Multiparous Holstein Cows

This study aimed to determine effects of postpartal relative body weight change (PRBWC) on production performance, serum biomarkers, and the relation between PRBWC and gastrointestinal microbiota. A total of 59 multiparous cows participated in this research. Every cow's PRBWC was calculated by the following equation: PRBWC = (BW21 - BW0)/BW0 × 100%, in which BW21 refers to body weight on Day 21 post-calving and BW0 refers to body weight on the day of parturition. Among the 59 enrolled cows, cows with the top 21 ranked PRBWC values were categorized into the high PRBWC (H-PRBWC) group; cows with the bottom 21 ranked PRBWC values were categorized into the low PRBWC (L-PRBWC) group. PRBWC did not have significant influences on average daily milk yield (ADMY). However, on Day 21, cows in the H-PRBWC group displayed significantly higher body weight (BW) and body condition scores (BCS) (BW, p = 0.02; BCS, p < 0.01). Additionally, levels of serum glucose (GLU) and albumin (ALB) were significantly higher in the H-PRBWC group on Day 21 (GLU, p = 0.05; ALB, p < 0.01), while the lipopolysaccharide-binding protein (LBP) level was significant lower (p = 0.03). Moreover, the microbiota of fecal samples on Day 0 (FE0) differed notably between groups, as evidenced by various alpha diversity indices, including Shannon (p = 0.02), Simpson (p = 0.03), Pielou_e (p = 0.02), and principal coordinate analysis (p = 0.002). The relative abundances of Monoglobus, norank_f__UCG-010, and Christensenellaceae_R-7_group were significantly higher in the H-PRBWC group (p < 0.05), while the relative abundances of Clostridium_sensu_stricto_1, Turicibacter, and Romboutsia were significantly lower (p < 0.05). Pathways related to amino acid biosynthesis were significantly enriched in the FE0 of the H-PRBWC group, while pathways involved in carbohydrate metabolism were significantly upregulated in the FE0 of the L-PRBWC group. This study argues the potential of PRBWC to describe alteration of energy status in the postpartum, evidenced by production performance, serum biomarkers, and the fecal microbiota.

Former Food and Agro-Industrial By-Products in Dairy Cow Diets: Effects on Milk Quality and Cheese Production

The use of former foodstuff and by-products in cow diets could improve the environmental sustainability of livestock. However, knowledge about the effects of these feeds in ruminant diets on the quality of dairy products is lacking. This study investigated the effects of integrating wheat distillers' grain with solubles (WDGS) and a former foodstuff product (FFP) into the diet of dairy cows on milk and cheese quality. The environmental impact of the two feeding systems has been evaluated by LCA. A double crossover design was set up with 84 Holstein cows, alternating a control diet and a circular one. In the circular diet, traditional feeds were partially replaced with 4 kg/d WDGS and 3 kg/d FFP. The results showed no effects on dry matter intake and milk yield, while fiber digestibility improved. A reduction in the milk fat content and a modification of the fatty acid profile of milk and cheese were observed. Conversely, cheese yield, composition, and sensory attributes were not affected. The environmental impact of the diet was significantly reduced in terms of land occupation, net fresh water, and global warming potential. These findings suggest that these feeds can be safely included in dairy cow diets. This approach could significantly contribute to reducing greenhouse gas emissions, enhancing the sustainability of the dairy system.

Effects of including a palmitic acid-enriched supplement in low- and high-starch diets on milk production and energy partitioning of primiparous and multiparous dairy cows between mid and late lactation

The aim of our study was to assess the effects of low- or high-starch diets with or without palmitic acid (C16:0) supplementation on the yield of milk, milk components, and energy partitioning of primiparous and multiparous dairy cows between mid and late lactation. Thirty-two Holstein cows, 12 primiparous (163 ± 33 DIM; mean ± SD) and 20 multiparous (179 ± 37 DIM; mean ± SD), were used in a split-plot Latin square design. Parity was considered the main plot, and within each plot, treatments were then randomly assigned in a replicated 4 × 4 Latin square with 21-d periods and balanced for carryover effects. Treatments were in a 2 × 2 factorial arrangement of dietary starch level and fatty acid (FA) supplementation as main factors. The starch factor comprised either low (LS; 16% of diet DM) or high (HS; 32% of diet DM) dietary starch. Dietary starch was altered by varying the proportion of ground corn, whole cottonseed, and soyhulls, with LS and HS diets containing ∼15% and 18% forage NDF (fNDF) and ∼37% and 25% NDF, respectively. The FA supplementation factor consisted of either control with no FA supplementation (CON) or a C16:0-enriched supplement at 1.5% of diet DM replacing soyhulls (PALM). Compared with LS, HS increased plasma insulin (0.20 μg/L) and energy partitioning to body reserves (2.04 percentage units), tended to increase BCS and BW change, and decreased DMI (1.10 kg/d), milk fat yield (0.04 kg/d), and MUN (2.10 mg/dL). Compared with CON, PALM increased energy output to milk (1.10 Mcal/d) and the yields of milk fat (0.10 kg/d), 3.5% FCM (1.90 kg/d), and ECM (1.60 kg/d), and had no effect on BW-related variables. We observed a 3-way interaction between parity, starch, and FA supplementation affecting multiparous but not primiparous cows, where PALM increased plasma insulin concentration (0.14 μg/L) in LS but had the opposite effect in HS by tending to decrease insulin. Our results demonstrate important interactions between parity, starch levels, and FA supplementation. Overall, feeding a low-starch diet to mid- and late-lactation dairy cows helped prevent excessive body condition and weight gain while increasing milk fat yield compared with a high-starch diet. Multiparous cows may benefit the most from a low-starch diet because multiparous cows seemed more prone to accumulating body reserves. Feeding a C16:0-enriched supplement increased milk fat yield and ECM without increasing weight gain, regardless of starch level or parity.

Effects of Dietary Coated Folic Acid and Folic Acid Addition on Lactation Performance, Rumen Fermentation, and Hepatic Lipid Content in Early Lactation Dairy Cows

This study evaluated the influences of coated folic acid (CFA) and folic acid (FA) on lactation performance, apparent digestibility, rumen volatile fatty acid (VFA) production, blood metabolism, and hepatic lipid content in cows. A total of 140 Holstein cows were allocated to seven groups in a randomized block design. Cows in the control received no addition, those in the in low CFA (LCFA), medium CFA (MCFA), and high CFA (HCFA) groups received CFA at 135, 270, and 405 mg FA/d, and those in the low FA (LFA), medium FA (MFA), and high FA (HFA) groups received FA at 135, 270, and 405 mg/d. The experiment began 5 weeks before calving to 6 weeks after calving. When increasing the level of CFA, the fat-corrected milk (FCM), fat and protein yields, de novo fatty acid content, and feed efficiency increased linearly. A linear increase was observed for nutrient digestibility and ruminal total VFAs. The blood total protein, albumin, superoxide dismutase, glutathione peroxidase, and folate increased linearly, but blood non-esterified fatty acids and β-hydroxybutyric acid and hepatic lipids decreased linearly. When increasing the level of FA, the FCM and milk fat yields increased linearly, but the rumen total VFA increased quadratically. Compared with MFA, cows receiving MCFA had a greater milk yield and lower hepatic lipids. Overall, the addition of CFA increased the milk yield and decreased the hepatic lipid content in cows.

Dietary macronutrient composition and partial soybean meal replacement with slow-release urea: Effects on performance, digestibility, rumen fermentation, and nitrogen metabolism in dairy cows

A 2 × 2 factorial arrangement of treatments was used to investigate the interactive effects of dietary macronutrient composition (high-starch, low-fat, low-fiber [HsLFF] diet or low-starch, high-fat, high-fiber [LsHFF] diet) and N source (soybean meal [SBM] or partially replaced by slow-release urea [SRU]) on lactation performance, rumen fermentation, N utilization efficiency, nutrient digestibility, blood metabolites, and feeding behavior in cows. A replicated 4 × 4 Latin square design was used involving 12 multiparous Holstein cows (milk yield of 40.5 ± 5.6 kg/d, BW of 590 ± 20 kg; 81 ± 12 DIM). The HsLFF diet contained 300 g/kg starch, 31.3 g/kg fat, and 301 g/kg NDF, without straw or additional fat. In contrast, the LsHFF diet contained 195.5 g/kg starch, 60.8 g/kg fat, and 367.5 g/kg NDF, enriched with wheat straw (100 g/kg), and additional fat (34 g/kg). The diets were formulated to be iso-nitrogenous and isocaloric. Cows fed the HsLFF diet had greater DM intake, digestibility of DM and CP, milk yield, and milk protein percentage, but lower intakes of NDF, and physically effective NDF, and milk fat percentage than cows fed the LsHFF diet. Replacing SBM with SRU significantly increased milk solids yield without affecting other lactation performance or BW. Cows fed the LsHFF diet had higher ruminal pH and branched-chain VFA proportions but lower total VFA concentrations compared with the HsLFF diet, while those on the LsHFF-SRU diet had the highest ruminal ammonia levels. Compared with the HsLFF diet, cows fed LsHFF had lower NE intake, milk energy output and energy requirement for maintenance, although energy balances were similar among groups. The HsLFF diet improved N utilization, resulting in higher N content in milk and lower N excretion in feces. Blood metabolite studies showed significant interactions between the main factors, particularly for blood glucose and creatinine, with the lowest levels in cows fed the LsHFF-SRU and LsHFF-SBM diets. In addition, alanine aminotransferase levels were higher in cows fed the LsHFF diet than in cows fed the HsLFF diet. This could indicate early-stage liver stress due to the metabolic imbalance caused by a high-fat, low-starch diet, which can alter energy metabolism. Cows on the HsLFF-SRU diet had the highest glucose levels, indicating possible changes in carbohydrate metabolism or a higher metabolic rate. The concentration of BUN increased steadily after feeding in the LsHFF diet and peaked after 4 h in the LsHFF-SRU diet, with no difference between N sources in the HsLFF diet. Partial replacement of SRU with SBM had no effect on BUN. The interaction between the main factors had a significant effect on MUN content, which was highest in LsHFF-SRU and lowest in HsLFF-SRU, with no difference between the N sources in the HsLFF diets. Overall, while diets with reduced starch and increased fiber and fat compromised lactation performance, partially substituting SRU with SBM helped maintain milk production and milk nitrogen efficiency. However, the LsHFF-SRU diet was less efficient in N utilization, as shown by higher levels of ruminal ammonia, BUN and MUN.

Developmental programming of production and reproduction in dairy cows: V. Association of the main and interactive effects of maternal level of milk production and milk fat to protein ratio with offspring's birth weight, survival, and productive and reproductive performance from birth to the first lactation period

Level of dam milk production (DMP) and dam milk fat to protein ratio (DFPR), as an indicator of metabolic status in dairy cows, have been identified to be associated with productive and reproductive performance of the offspring. Yet whether the interaction of DMP by DFPR can be associated with performance of the offspring have not been studied to our knowledge. Therefore, the present study was conducted to investigate the association of the main and interactive effects of DMP and DFPR with offspring's birth weight, survival, milk yield and fertility. To this end, data of birth weight, culling rate, milk yield and reproductive variables of offspring born to lactating dams (n = 14,582) and data associated with DMP and DFPR during 305-day lactation were retrieved. Afterwards, offspring were classified in three categories of DMP, including DMP1 (dams with <10.00 × 103 kg of 305-day milk production), DMP2 (dams with ≥10.00 × 103 kg and <14.00 × 103 kg of 305-day milk production), DMP3 (dams with ≥14.00 × 103 kg of 305-day milk production), and three categories of DFPR, including DFPR1 (offspring born to dams with <1.00 FPR), DFPR2 (offspring born to dams with ≥1.00 and < 1.40 FPR) and DFPR3 (offspring born to dams with ≥1.40 FPR). Statistical analysis revealed no association of the interaction effect of DMP by DFPR with investigated variables in the offspring (P > 0.05). However, the main effect of DMP was positively associated with milk yield, but negatively associated with survival, age at first insemination and conception during nulliparity, and transgenerational improvement in milk yield in the offspring (P < 0.05). Moreover, the main effect of DFPR was positively associated with birth weight, survival and first service conception rate during nulliparity, but negatively associated with metabolic status and reproductive performance during primiparity in the offspring (P < 0.05). In conclusion, the present study did not find any interaction effect of DMP by DFPR on productive and reproductive variables in the offspring. This finding implicates the association of DMP with milk production in the offspring was regardless of DFPR. Moreover, this finding implies the association of DFPR with postpartum metabolic status and reproductive performance in the offspring was regardless of DMP.

Effects of raw and roasted high oleic soybeans on milk production of high-producing dairy cows

Processing method of soybeans has the potential to influence dairy cow production performance, therefore we determined the effect feeding raw or roasted, ground high oleic acid soybeans (HOSB) on production responses of high-producing dairy cows. Thirty-six multiparous Holstein cows (45.6 ± 6.22 kg/d of milk; 110 ± 61 DIM) were randomly assigned to treatment sequences in a 4 × 2 Truncated Latin square design with 35-d periods. Treatments were: 1) control diet containing soybean meal and soybean hulls (CON), 2) 16% roasted and ground HOSB (RST), 3) 16% raw and ground HOSB (RAW-D), and 4) 16% raw and ground HOSB + additional rumen by-pass protein (RAW-U). High oleic acid soybeans replaced conventional soybean meal and hulls in the control diet and rumen by-pass protein replaced soybean meal in RAW-U to maintain diet nutrient composition (%DM) of ∼28.0% NDF, 21.3% forage NDF, 27.3% starch, and 17.8% CP. Fatty acid content of CON, RST, RAW-D, and RAW-U was 1.60, 4.30, 4.36, and 4.34%DM, respectively. Pre-planned contrasts included the overall effect of HOSB inclusion {CON vs. HOSOY [1/3 (RST + RAW-D + RAW-U)]}, the effect of soybean processing {RST vs. RAW [1/2 (RAW-D + RAW-U)]}, and the effect of increasing RUP content within the raw HOSB treatments (RAW-D vs RAW-U). For most variables tested, there were significant interactions between treatment and week, as HOSOY increased production variables compared with CON and RST increased production responses compared with RAW, with only the magnitude of difference varying between weeks. Overall, HOSOY increased DMI and yields of milk, 3.5% FCM, ECM, and milk fat, but did not affect milk protein yield. RST did not impact DMI but increased yields of milk, 3.5% FCM, ECM, milk fat, and milk protein. Compared with RAW-D, RAW-U increased yields of milk and milk protein and tended to increase ECM. Overall, HOSB inclusion of 16% DM increased production responses in high-producing dairy cows, but roasted HOSB had a greater impact than raw HOSB, and the addition of rumen-bypass protein positively affected milk protein response.

Lactation performance, feed efficiency, and blood metabolites of dairy cows treated with recombinant bovine somatotropin: A systematic review and meta-analysis

A systematic review and meta-analysis were conducted to assess the impact of recombinant bovine somatotropin (rbST) on lactation performance, feed efficiency, and blood metabolites in dairy cows. In the systematic review, articles were selected based on the following criteria: (1) Data focusing on the influence of bovine somatotropin doses on milk production; (2) Submission of original data; (3) Articles published in journals; and (4) Articles in English or Portuguese. The analysis of variance was used with a completely randomized design and mixed models methodology. Polynomial regression was applied to significant fixed effects (rbST dose). The use of rbST resulted in increased milk yield and 4% fat-corrected milk yield, while fat, protein, and lactose contents remained unaffected. Dry matter and metabolizable energy intakes, as well as milk/feed efficiency, exhibited a linear increase, but body condition score (BCS) was negatively impacted. The administration of rbST led to higher blood concentrations of triglycerides and insulin. Cows treated with rbST showed a 23% increase in non-esterified fatty acid (NEFA) concentrations compared to non-treated cows. Additionally, growth factors IGF-1 and IGF-2 displayed a linear increase with rbST treatment. In summary, rbST administration increased milk yield and fat-corrected milk yield without affecting milk components. However, despite increasing intake, it resulted in BCS losses and alterations in blood parameters such as NEFA, IGF-1, and IGF-2.

Effects of increasing dietary inclusion of high oleic acid soybeans on milk production of high-producing dairy cows

Recent research has highlighted the importance of dietary fatty acid profile of fatty acid supplements on production responses of high-producing dairy cows. Conventional soybeans contain ∼15% oleic acid and ∼50% linoleic acid whereas high oleic acid soybeans (HOSB) contain ∼70% oleic acid and ∼7% linoleic acid. We determined the effect of increasing dietary inclusion of roasted and ground HOSB on production responses of high-producing dairy cows. Twenty-four multiparous Holstein cows (50.7 ± 4.45 kg/d of milk; 122 ± 57 DIM) were randomly assigned to treatment sequences in a replicated 4 × 4 Latin square design with 21-d periods. Treatments were increasing doses of HOSB at 0, 8, 16, and 24% DM. The HOSB replaced conventional soybean meal and hulls to maintain similar diet nutrient composition (% DM) of 27.4 - 29.4% (NDF), 20.6% forage NDF, 27.5% starch, and 15.9 - 16.5% CP. Total fatty acid content of treatments was 1.65, 3.11, 4.52, and 5.97% DM, respectively. Pre-planned polynomial orthogonal contrasts included the linear, quadratic, and cubic effects of increasing HOSB. Increasing dietary inclusion of HOSB linearly decreased DMI and milk urea nitrogen and increased yields of milk, 3.5% fat corrected milk, energy corrected milk, and milk fat, and quadratically increased milk protein. The increased response to milk fat was due to an increase in preformed milk fatty acids. Due to the increase in milk component yields and decrease in DMI, there was an increase in feed efficiency. Increasing HOSB inclusion linearly decreased plasma BUN concentration and tended to decrease plasma insulin. Increasing HOSB had no effect on BW change or BCS change. In summary, increasing dietary inclusion of HOSB up to 24% DM increased production responses of high-producing dairy cows and did not affect body reserves.

Developmental programming of production and reproduction in dairy cows: IV. Association of maternal milk fat and protein percentage and milk fat to protein ratio with offspring's birth weight, survival, productive and reproductive performance and AMH concentration from birth to the first lactation period

Although the association of maternal milk production with developmental programming of offspring has been investigated, there is limited information available on the relationship of maternal milk components with productive and reproductive performance of the offspring. Therefore, the present study was conducted to analyze the association of maternal milk fat and protein percentage and milk fat to protein ratio with birth weight, survival, productive and reproductive performance and AMH concentration in the offspring. In study I, data of birth weight, milk yield and reproductive variables of offspring born to lactating dams (n = 14,582) and data associated with average maternal milk fat percentage (MFP), protein percentage (MPP) and fat to protein ratio (MFPR) during 305-day lactation were retrieved. Afterwards, offspring were classified in various categories of MFP, MPP and MFPR. In study II, blood samples (n = 339) were collected from offspring in various categories of MFP, MPP and MFPR for measurement of serum AMH. Maternal milk fat percentage was positively associated with birth weight and average percentage of milk fat (APMF) and protein (APMP) and milk fat to protein ratio (FPR) during the first lactation, but negatively associated with culling rate during nulliparity in the offspring (P < 0.05). Maternal milk protein percentage was positively associated with birth weight, APMF, APMP, FPR and culling rate, but negatively associated with milk yield and fertility in the offspring (P < 0.05). Maternal FPR was positively associated with APMF and FPR, but negatively associated with culling rate, APMP and fertility in the offspring (P < 0.05). However, concentration of AMH in the offspring was not associated with MFP, MPP and MFPR (P > 0.05). In conclusion, the present study revealed that maternal milk fat and protein percentage and their ratio were associated with birth weight, survival, production and reproduction of the offspring. Yet it was a preliminary research and further studies are required to elucidate the mechanisms underlying these associations.

The Effect of a Direct Fed Microbial on Liveweight and Milk Production in Dairy Cattle

This longitudinal study aimed to quantify the effects of dietary supplementation of a direct-fed microbial (DFM) consisting of three lactobacilli isolates on milk yield, milk fat and protein yields, somatic cell count (SCC), and liveweight in a single dairy herd in Australia. A total of 150 dairy cows were randomly selected based on parity and days in milk and divided into two groups: control (n = 75) and DFM treatment (n = 75). Throughout the study, the two groups of cows were housed separately in a dry lot yard, and each group had their own feeding area. For the DFM treatment group, selected cows in mid-lactation were supplemented with 10 mL/cow/day of the DFM via top dressing of the feed for the remainder of the lactation and through the dry period, extending into subsequent lactation. The control group had no supplementation. The milk yield and liveweight were recorded daily. Milk samples were collected every two months for milk component analysis (fat, protein, and somatic cell count [SCC]). The DFM-treated cows gained more liveweight across the study (19.40 kg, 95% CI 0.44 kg; 38.30 kg, p = 0.05) compared to the control cows. In the second production year, the DFM-treated cows mobilized more liveweight (-6.06 kg, 95% CI -10.49 kg; -1.61 kg, p = 0.01) and produced more milk (0.39 L/d 95% CI 0.10; 0.89, p = 0.05). Over a full lactation, DFM cows yielded at least 258 L (95% CI 252 L; 265 L) more milk than controls. No significant differences were found in fat and protein yield or SCC. This study suggests that consistent and ongoing supplementation with a Lacticaseibacillus- and Lentilactobacillus-based DFM could have a positive effect on milk production, but further research is needed to understand the underlying mechanism.

Cloprostenol sodium improves reproductive performance of multiparous sows during lactation

This study aimed to determine the effect of prostaglandin F2α (PGF2α) analog (D-cloprostenol sodium and DL-cloprostenol sodium) administration on the milk yield of multiparous sows (MS) and piglet growth performance. In total, 320 Landrace×Yorkshire parturient MS were randomly divided into three groups on day 115 of pregnancy: without treatment (N = 50), with 75 μg D-cloprostenol sodium (N = 137), and with 200 μg DL-cloprostenol sodium (N = 133). After delivery, the sows treated with D-cloprostenol sodium and DL-cloprostenol sodium were randomly allocated into three subgroups, respectively: (i) no additional treatment after farrowing; (ii) administration of cloprostenol sodium at 3 h and 5 days after farrowing; and (iii) administration of cloprostenol sodium at 3 h, 5 days, and 10 days after farrowing. Cloprostenol sodium effectively induced sows to synchronize parturition approximately 23 h after administration and increased the daytime delivery rates (p < 0.05). Compared with DL-cloprostenol sodium, D-cloprostenol sodium shortened the farrowing duration and birth interval of sows for inducing farrowing (p < 0.05). Moreover, we observed that a single administration of both D-cloprostenol sodium and DL-cloprostenol sodium a day before delivery significantly reduced the rates of stillborn piglets type II in MS (p < 0.05). Compared to no treatment and single treatment with cloprostenol sodium, quartic treatments with cloprostenol sodium significantly increased the daily feed intake of MS, litter weight after weaning, and average daily gain of piglets (p < 0.05). Cloprostenol sodium improved the 21-day milk yield, with D-cloprostenol sodium showing the best effect, which increased lactation ability by 30.30% (176.72 kg vs. 135.63 kg) (p < 0.05). DL-cloprostenol sodium followed closely, increasing lactation ability by approximately 25.00% (169.71 kg vs. 135.63 kg) (p < 0.05). During lactation, sows administered with D-cloprostenol sodium observed increased serum prolactin levels. Compared to untreated sows, the sows administered with D-cloprostenol sodium and multiple DL-cloprostenol sodium visibly shortened the weaning-to-estrus interval (WEI) and weaning-to-service interval (WSI) (p < 0.05). Furthermore, quartic injections of D-cloprostenol sodium resulted in an 18 percentage point increase in the pregnancy rate of breeding sows compared to controls (82.61% vs. 64.58%) (p > 0.05). In summary, cloprostenol sodium could enhance the reproductive performance of MS, particularly in terms of lactation performance. Additionally, the effect of quartic injections of D-cloprostenol sodium was the most pronounced.

Early versus late body condition score loss in dairy cows: Reproductive performance

This study aimed to compare milk production and reproductive performance in high yield Holstein cows that lose BCS early and late in the postpartum period. Lactating dairy cows (n = 76) were received first timed AI at 60 to 75 DIM using the farm-managed estradiol-progesterone-GnRH-based timed AI protocol. The BCS of all cows was daily evaluated by automated BCS cameras. Aiming to evaluate the effect of the days in milk (DIM) in which a cow reached the nadir BCS on the reproductive parameters, cows were separated into two groups: early BCS loss (n = 42), cows that reached the nadir BCS ≤ 34 DIM, and late BCS loss (n = 34), cows that reached the nadir BCS > 34 DIM. The optimal cut-off point for determining the relationship between days to nadir BCS and pregnancy by 150 DIM (P150) was calculated using the receiver operating characteristic (ROC) curve. From the ROC analysis, the cut-off was 34 DIM (Se, 80.9%; Sp, 66.7%; AUC, 0.74; P < 0.01). No differences (P>0.05) were detected between groups on the BCS and milk production. The average of milk production in both groups was 46.65 ± 6.15 Kg/day. Cows that reached the nadir BCS early postpartum presented lower (P < 0.01) calving interval and greater (P < 0.01) pregnancy at first AI and P150. In summary, cows that lost BCS early had better reproductive performance and had similar milk yield compared with cows that lost BCS late in the postpartum period.