Reproductive Performance Of Dairy Cows Research Articles

Harnessing Vaginal Probiotics for Enhanced Management of Uterine Disease and Reproductive Performance in Dairy Cows: A Conceptual Review.

Uterine disease in cattle impairs reproductive performance and profitability and increases antibiotic use and antimicrobial resistance. Thus, probiotics offer a promising alternative therapy. This review presents conceptual findings on the efficacy of probiotics in managing uterine diseases and fertility in cows. Probiotics containing Lactobacillus spp. and Bifidobacterium spp. individually or as composite formulations are known to improve fertility. Strategic intravaginal administration of these formulations would likely enhance uterine immunity, particularly during the postpartum period. While current findings on the benefits to uterine health are encouraging, there is still significant knowledge missing, including a lack of empirical information from large-scale field trials. This review underscores the need for evidence-based guidelines for probiotics, such as genomic selection of formulations, targeted delivery, or potential synergy with other interventions. Future research should address these gaps to maximize the potential of probiotics in managing uterine diseases and enhancing the reproductive health of dairy cattle.

The association between time-series milk β-hydroxybutyrate dynamics and early reproductive performance of dairy cows

The DeLaval Herd Navigator is an on-farm sensor system that measures on a frequent basis milk progesterone (P4) and β-hydroxybutyrate (BHB) in individual cows to closely monitor reproductive performance and energy balance. This information provides the opportunity to investigate the dynamics of BHB measured in milk (mBHB) and study the association between mBHB and early reproductive performance. The objectives of the study were (1) to describe mBHB dynamics within the first 20 d in milk (DIM), and (2) to evaluate the association between mBHB dynamics and early reproductive performance at cow-level. Two-year time-series data from 4,133 dairy cows in 38 Dutch dairy farms were available for analysis. Data included information on mBHB, daily milk yield and the indicators of early reproductive performance, days from calving to resumption of cyclicity, days from calving to first estrus, and days from calving to first insemination. The following mBHB dynamic parameters were defined based on the first 20 DIM for each individual cow: average mBHB (AvgBHB), DIM when mBHB was for the first time ≥80 μmol/L (OnsetKeto), the total number of consecutive days a cow had mBHB concentration ≥80 μmol/L, and the number of measurements mBHB concentration was ≥80 μmol/L. Three Cox proportional hazard regression models with random herd effect were developed to evaluate the association between cow level mBHB dynamics and days from calving to resumption of cyclicity, first estrus, and first insemination. Results showed that the mean AvgBHB within 20 DIM among all cows was 73 μmol/L. The mean OnsetKeto within 20 DIM, was 8 DIM. Among all cows having hyperketolactia, 55.8% (1,350/2,419) had OnsetKeto in the first week of lactation. In total, 41.5% (1,714/4,133) of the cows did not have OnsetKeto in the first 20 DIM. An early onset of hyperketolactia was associated with delayed fertility events. Cows with higher AvgBHB have a prolonged time interval from calving to resumption of cyclicity and first estrus. Information on mBHB dynamics and the association with early reproductive performance provides insights that might be helpful to improve reproductive performance of individual dairy cows.

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

Although some studies investigated the relationship of dam milk production (DMP) with offspring birth weight and productive performance, limited information is available on the association of level of DMP with reproductive performance in dairy cows. Therefore, the present study was conducted to understand whether dams with various levels of milk production produce offspring with different fertility. In study I, offspring were classified based on the level of DMP into five categories, including DMP1 (dams with <10.00 × 103 kg of 305-day milk production), DMP2 (dams with ≥10.00 × 103 kg and <12.00 × 103 kg of 305-day milk production), DMP3 (dams with ≥12.00 × 103 kg and <14.00 × 103 kg of 305-day milk production), DMP4 (dams with ≥14.00 × 103 kg and <16.00 × 103 kg of 305-day milk production) and DMP5 (dams with ≥16.00 × 103 kg of 305-day milk production). In study I, data of birth weight, milk yield and reproductive variables of 14,536 offspring born to lactating dams and corresponding data of DMP were retrieved. In study II, blood samples (n = 339) were collected from offspring in various categories of DMP for measurement of serum AMH. Offspring were heavier at birth in DMP4 and DMP5 categories than DMP1 and DMP2 categories (P < 0.05). Milk yield of offspring increased as DMP elevated (P < 0.05); however, offspring in DMP1 and DMP2 categories produced higher milk as compared with their dams during primiparity (P < 0.05) whereas offspring in DMP3, DMP4 and DMP5 categories produced less milk as compared with their dams during primiparity (P < 0.05). Milk fat to protein ratio during the first month of lactation was greater in DMP4 and DMP5 categories than DMP1 category (P < 0.05). Offspring of DMP4 and DMP5 categories were inseminated and conceived at younger ages than offspring of DMP1 category during nulliparity (P < 0.05). Calving to conception interval was longer in DMP5 than DMP1 category in primiparous offspring (P < 0.05), but concentration of AMH did not differ among various categories of DMP (P > 0.05). In conclusion, dams with greater level of milk production produced heavier offspring with higher milk yield but worse transgenerational improvement in milk production and diminished reproductive performance, which were seemingly under higher pressure of negative energy balance during the first month of lactation.

Horário da inseminação artificial na taxa de prenhez das vacas Holandesas usando monitoramento automatizado de atividades

ABSTRACT: This study evaluated the probability of pregnancy and associated factors for two times artificial inseminations (AI), 8 or 10 hours after automated activity monitoring (AAM) alarm on the first postpartum AI of 1,054 Holstein dairy cows. The estrus was synchronized by prostaglandin or estradiol-progesterone program. Stepwise logistic regression was performed to analyze the probability of pregnancy, and associated factors (activity, estrus intensity, parity, peripartum health, retained placenta, postpartum vaginal discharge, and season). The highest pregnancy rates were obtained with multiparous animals, inseminated ten hours after the AAM alarm, in the fall or winter season, with a high activity peak and estrus intensity (P &lt; 0.05). Peripartum diseases, retained placenta, and postpartum vaginal discharge negatively influenced the pregnancy rate, regardless of parity. Thus, the optimization of AAM models by including on-farm measures like parity, peripartum health history, and environmental conditions may favor the correct identification of estrus and improve the AAM alarm regarding the ideal moment for AI, increasing the reproductive performance in dairy cows.

Impact of different hormonal protocols for the treatment of smooth inactive ovaries (SIO) and the subsequent reproductive performance in dairy cows

Impact of different hormonal protocols for the treatment of smooth inactive ovaries (SIO) and the subsequent reproductive performance in dairy cows

The effect of the silvopastoral system on milk production and reproductive performance of dairy cows and its contribution to adaptation to a changing climate in the drylands of Benin (West-Africa)

Knowledge about dairy cows raised in small-scale agroforestry systems in dryland areas is of paramount importance to inform policy and decision making in the dairy production sector in the current context of climate change. The aim of this study was to evaluate the effect of integrated farming systems on daily milk yield and demographic traits of dairy cows in drylands. A study conducted on 447 dairy cows was carried out to compare their milk yield and demographic parameters under different small-scale agroforestry systems in drylands of Benin: traditional silvopasture (TSS); Improved silvopasture (ISS); Small Integrated Agrosilvopasture (SIAS) and Large Integrated Agrosilvopasture (LIAS). The type of cattle farms had a significant effect (p &amp;lt; 0.05) on daily milk yield and demographic traits. Dairy cattle from ISS farms had the highest daily milk yield regardless of the type of dairy cow breed. Demographic traits of herds were significantly (p &amp;lt; 0.05) influenced by the type of dairy cattle farms. The proportion of lactating cows was higher (p &amp;lt; 0.05) in herds of ISS (48.4%) followed by those in TSS and LIAS (36.1 and 25.0% respectively) while SIAS was the lowest in (14.4%). The pre-weaning mortality rate was higher (p &amp;lt; 0.05) in TSS and LIAS farms (18.3 and 17.6 % respectively) compared to SIAS and ISS farms (5.20 and 4.60 % respectively). The fertility rate was higher (p &amp;lt; 0.05) in ISS and SIAS farms (92.3 and 89.6% respectively) compared to TSS and LIAS farms (68.3 and 74.2% respectively). The weaning productivity was higher (p &amp;lt; 0.05) in ISS and SIAS (88.6 and 85.8 % respectively) than in TSS and LIAS farms (66.1 and 67.6 % respectively). This study showed that ISS farms are characterized by higher milk yield and demographic parameters. ISS systems can then be promoted in smallholder cattle farming to improve milk production and reproductive performance of dairy cows in drylands.

Evaluation of breeding objectives, breeding practices and reproductive performance of indigenous dairy cows in selected districts of Kaffa Zone, South West Ethiopia.

Breeding objectives are designed to achieve targeted dairy cow production goals, which can be affected by production type, farmer preferences, environmental factors and genetic factors individually or in combination. Breeding practices, such as both controlled and uncontrolled, and artificial insemination (AI) are the tools used to obtain the desired breeding objectives. The lower reproductive performance of indigenous dairy cows affects the total milk production and calf crops that are produced during their lifetime. Designing appropriate breeding objectives and breeding practices can improve the reproductive performance of dairy cows and their overall production performance. The current study was conducted with the objective of evaluating the breeding, practices and performance of indigenous dairy cattle in the south western part of Ethiopia. The districts of Gesha and Chena were purposefully chosen. The study design for the 384 household surveys was a cross-sectional survey with a simple random sample approach. Data analysis was carried out by MS-Excel (2010) and the general linear model procedure of SAS of 2008. The current study revealed that methods of breeding were predominantly natural-controlled mating, followed by natural-uncontrolled mating and AI in descending order. Breeding objectives were input function, output function, sociocultural and economic functions and assets and security functions in decreasing order of rank. Reproduction performance indexes of indigenous dairy cows age at first service (3.72±0.05 years), age at first calving (AFC) (4.71±0.07 years), calving interval (CI) (1.58±0.03 years), days open (DO) (4.26±0.11 months), services per conception in natural mating (1.4±0.08) and AI (2.73±0.14), age of bull at maturity (4.17±0.74 years), interoestrus interval (23.18±0.61 days), calves crop (7.53±0.22) and the life span of indigenous dairy cow (11.94±0.26 years) were significant (p<0.01) between two districts, whereas the values of age of bull at maturity and number of services per conception in natural mating were significant (p<0.05) between districts. Using AI and major reproduction performances, such as AFC, CI and DO of indigenous dairy cows in the study area, were very low. Therefore, concerned bodies should intervene to improve reproduction performance through the utilization of AI techniques, with the integration of forage development activities and improvements in livestock health care.

Postpartum health is associated with detection of estrus by activity monitors and reproductive performance in dairy cows

The objective of this prospective observational study was to investigate associations of postpartum health with estrus detection (ED) by activity monitors and pregnancy outcomes in dairy cows. A total of 1,743 Holstein cows from 2 commercial dairy herds in Ontario, Canada were enrolled 3 wk before expected parturition and examined for health variables until 9 wk postpartum. Body condition score (BCS) and lameness were measured at 3 wk prepartum, and serum concentrations of total Ca, haptoglobin (Hp), and nonesterified fatty acids were measured at 2 and 6 ± 2 d in milk (DIM), and blood β-hydroxybutyrate (BHB) and metritis were assessed at 4, 8, 11, and 15 ± 2 DIM. Cows were examined for purulent vaginal discharge (PVD) and endometritis (ENDO) by endometrial cytology at wk 5, for lameness at wk 3 and 7, for BCS at wk 9 postpartum, and for time to onset of cyclicity by biweekly serum progesterone (P4) measurements. Additional disease data were obtained from farm records. Reproductive management for first AI was primarily based on ED by activity monitors until at least 75 DIM, and cows not detected in estrus were synchronized. Data were analyzed in multivariable logistic or Cox proportional hazards regression models including blood markers, health variables, potential covariates, and herd as a random effect. Estrus was detected in 77% of primiparous and 66% of multiparous cows between 50 or 55 DIM and 75 DIM. In 1,246 cows, the model-predicted probability of ED (percentage point difference) was lower in cows that had retained placenta (-14%), ENDO (-7%), PVD (-8%), delayed cyclicity (no P4 > 1 ng/mL by wk 9; -12%), or ≥0.5-point BCS loss (-14%) compared with cows without each of these risk factors, and it was negatively associated with blood BHB at 15 DIM. Considering only variables measured on farm (not requiring laboratory analysis), the probability of ED was lower (56 vs. 81%) in cows with >1 risk factor compared with cows without risk factors. The predicted probability of pregnancy at first artificial insemination (percentage point difference) was lower in cows that had ENDO (-7%) or PVD (-7%), and negatively associated with serum Hp at 6 ± 2 DIM. In cows detected in estrus by 75 DIM (n = 888), risk factors for reduced pregnancy rate by 250 DIM (adjusted hazard ratio (AHR); 95% confidence intervals) included difficult calving (AHR: 0.67; 0.45 to 1.00), metritis (AHR: 0.79; 0.61 to 1.01), PVD (AHR: 0.79; 0.65 to 0.97), or lameness (AHR: 0.79; 0.62 to 1.01), and it was negatively associated with serum Hp at 6 ± 2 DIM. Monitoring postpartum health may be used to identify cows that are more or less likely to be detected in estrus by activity monitors and to become pregnant in a timely manner. This would support a selective reproductive management program with targeted interventions.

Seasonal effects on multiparous dairy cow behavior in early lactation

Controlled studies have shown that heat stress abatement positively influences health, productivity, behavior, and reproductive performance of dairy cows during all stages of the lactation cycle. Based on previous findings, the present study focused on a better understanding of how seasonal changes affect the behavior of multiparous lactating dairy cows kept in typical free-stall housing with the objective to aid in the management of lactating cows exposed to variable environmental conditions. Automated monitoring devices (Nedap, the Netherlands) were used to assess behavioral activity of mature Holstein dairy cows during the “hot season” (HS; n = 19; July, August, and September) and the “cool season” (CS; n = 15; December, January, and February) under normal management conditions. Cows received a leg tag to measure daily lying time, and number of steps and standing bouts, and a neck tag to measure eating and rumination time. All cows were housed in sand-bedded freestall barns equipped with cooling systems (soakers and fans). Behavior, milk production and milk components were recorded for the first 9 wk of lactation after calving. Average temperature-humidity index (THI) was 78.2 ± 0.4 (± standard error) in the HS and 54.4 ± 0.2 in the CS. Fat-corrected milk yield was greater in the CS compared with HS during the first 5 wk of lactation. Milk protein percentage was lower in CS during the first 2 wk of lactation. In contrast with HS, milk fat percentage was greater in the CS. Compared with CS, overall, during HS cows spent less time eating, lying down, and tended to spend less time ruminating. In addition, exposure to high THI resulted in increases in standing bouts, and overall standing time in HS relative to CS. No differences in number of steps were observed between HS and CS. In summary, exposure to high THI during lactation seems to negatively affect the behavior and consequently the daily time budget of lactating Holstein cows, even under housing conditions with active cooling. A better understanding on how different seasons affect the daily time budget of lactating dairy cows may contribute to the development of more effective management strategies to decrease the negative effects of heat exposure.

Effect of Dam Body Conformations on Birth Traits of Calves in Chinese Holsteins.

The objective of this study was to explore the effect of dam body conformations on birth traits including stillbirth, dystocia, gestation length and birth weight of Chinese Holstein calves and to provide a reference for improving cow reproductive performance. We collected phenotype data on 20 conformation traits of Chinese Holstein cows and analyzed the impact of dam conformation trait linear scores on stillbirth, dystocia, gestation length and calf birth weight. The feet angle, set of rear legs, fore udder attachment and rear attachment height traits of the dairy cows significantly affected the risk of stillbirth. The risk of dystocia decreases with the increase in stature and pin width. The bone quality of dairy cows had a significant positive correlation with gestation length. There was a significant positive correlation between fore udder attachment and calf weight at birth. The birth weight of calves from cows with high body conformation traits was significantly higher than that of calves with a low composite score. These results suggest that improving the body conformation traits, especially the selection of mammary system and body shape total score, will be beneficial in improving the reproductive performance of dairy cows.

Effects of Ovarian Status at the Time of Initiation of the Modified Double-Ovsynch Program on the Reproductive Performance in Dairy Cows

Effects of Ovarian Status at the Time of Initiation of the Modified Double-Ovsynch Program on the Reproductive Performance in Dairy Cows

Impact of postpartum time period associated body condition score on reproductive performance in dairy cows

This study was designed to identify the time period at which the body condition score (BCS) most critically affects the reproductive performance after calving in dairy cows. Data were collected from 4865 lactation records (1821 from primiparous and 3044 from multiparous cows) on 28 dairy farms, including the BCS (at calving, and month 1 and the first artificial insemination [AI] after calving), the presence of peri- or postpartum disorders, reproductive data, and the weather. The data on the extent of BCS loss from calving to the first AI was divided into two periods, namely, between calving and month 1 after calving (period 1), and between month 1 and the first AI after calving (period 2). Cows with BCS of 3.0, 3.25 and ≥ 3.5 at the first AI after calving were more likely (P < 0.05-0.01) to be pregnant at 30 (odds ratio [OR]: 1.36, 1.64, and 1.90) and 45 (OR: 1.39, 1.75, and 1.99) days post-AI and more likely (P < 0.05-0.01) to be pregnant within 180 days after calving (hazard ratio [HR]: 1.18, 1.43, and 1.58) than cows with BCS of ≤2.75. In addition, cows who suffered a BCS loss of ≥0.5 units during period 1 tended to be less likely (HR: 0.79, P < 0.1) to be pregnant within 180 days after calving than cows without a BCS loss. Cows with BCS of 3.0, 3.25, and ≥3.5 at calving were less likely (P < 0.1-0.05) to lose their pregnancy (OR: 0.37, 0.33, and 0.16) than cows with BCS of ≤2.75. These results indicate that the linearly higher BCS (3.0, 3.25, and ≥3.5) at the first AI is positively associated with the probability of pregnancy per AI after the first AI and the likelihood of pregnancy within 180 days after calving, whereas a higher BCS loss of ≥0.5 units during period 1 was adversely associated with the likelihood of pregnancy within 180 days after calving.

Impact of subclinical mastitis on uterine health, reproductive performances and hormonal profile of Zebu × Friesian crossbred dairy cows in and around Jimma town dairy farms, Ethiopia

A longitudinal observational study was carried out from January 2020 to July 2021 to assess the impact of subclinical mastitis (SCM) on reproductive performance and its association with uterine health of crossbred dairy cows. The California Mastitis Test (CMT) and cytobrush technique were used to screen subclinical mastitis and subclinical endometritis, respectively. Milk samples positive for subclinical mastitis were subjected to bacteriological analysis. Data from 84 clinically healthy cows collected and analyzed. The present study revealed a prevalence of subclinical mastitis of 51.2% (43 of 84). The mean days from calving to first service interval were significantly longer in subclinical mastitis positive cows than negative (control) cows (120.51 ± 24.5 and 85.15 ± 28.3, respectively) (P < 0.05). The mean number of services per conception was significantly higher in positive cows (2.51 ± 0.83) than in negative cows (1.59 ± 0.81) (P < 0.05). Lower conception and pregnancy rates at first services were observed in subclinical mastitis cows. Risk factors analysis revealed that prevalence of subclinical mastitis significantly differed with the parity and body condition score (P < 0.05). The current study revealed that subclinical mastitis was significantly and directly associated with subclinical endometritis (P < 0.05). Subclinical mastitis significantly decreased (P = 0.000) progesterone concentrations and increased (P = 0.001) the cortisol concentrations. Staphylococcus aureus were the most predominant bacterial isolates from subclinical mastitic milk, followed by coagulase negative staphylococci (CNS) and streptococci. This study concludes a high prevalence of subclinical mastitis caused by Staphylococcus aureus could inflict harmful effects on reproductive performance of dairy cows, emphasizing the relevance of mastitis control programs in dairy farms.

Effects of source of supplementary trace minerals in pre- and postpartum diets on reproductive biology and performance in dairy cows

Our objectives were to evaluate the effects of complete replacement of inorganic salts of trace minerals (STM) with organic trace minerals (OTM) in both pre- and postpartum diets on ovarian dynamics, estrous behavior measured by sensors, preimplantation conceptus development, and reproductive performance in dairy cows. Pregnant cows and heifers (n = 273) were blocked by parity and body condition score and randomly assigned to either STM or OTM diets at 45 ± 3 d before their expected calving. Pre- and postpartum diets were formulated to meet 100% of recommended levels of each trace mineral in both treatments, taking into consideration both basal and supplemental levels. The final target concentrations of Co, Cu, Mn, Se, and Zn were, respectively, 0.25, 13.7, 40.0, 0.3, and 40.0 mg/kg in the prepartum diet, and 0.25, 15.7, 40.0, 0.3, and 63.0 mg/kg in the postpartum diet. The STM group was supplemented with Co, Cu, Mn, and Zn sulfates and sodium selenite, while the OTM group was supplemented with Co, Cu, Mn, and Zn proteinates and selenized yeast. Treatments continued until 156 d in milk (DIM) and were assigned to individual cows using automatic feeding gates. Starting at 21 DIM, ultrasonography examinations of the ovaries were performed weekly to determine the presence of a corpus luteum and postpartum resumption of ovarian cyclicity. Cows were presynchronized with 2 injections of PGF2α at 42 and 56 DIM. Estrous behavior was monitored using electronic activity tags that indirectly measured walking activity. Cows detected in estrus after the second PGF2α were inseminated, and those not detected in estrus by 67 DIM were enrolled in a synchronization program. Cows that returned to estrus after artificial insemination (AI) were reinseminated. Pregnancy diagnosis was performed 33 d after AI, and nonpregnant cows were resynchronized. Transcript expression of interferon-stimulated genes in peripheral blood leukocytes was performed in a subgroup of cows (STM, n = 67; OTM, n = 73) on d 19 after AI. A different subgroup of cows (28 STM, 29 OTM) received uterine flushing 15 d after AI for recovery of conceptuses and uterine fluid for analyses of transcriptomics and metabolomics, respectively. In addition, dominant follicle diameter, luteal size and blood flow, and concentration of progesterone in plasma were measured on d 0, 7, and 15 relative to AI. After flushing, PGF2α was given and the dominant follicle was aspirated 2 d later to measure the concentration of trace minerals by mass spectrometry. Estrous behavior, size of the dominant follicle and corpus luteum, concentration of progesterone, time to pregnancy, and proportion of cows pregnant by 100 d of the breeding period did not differ between treatments. A greater proportion of cows supplemented with OTM had a corpus luteum detected before presynchronization (64.3 vs. 75.2%), and primiparous cows supplemented with OTM tended to resume cyclicity earlier than their STM counterparts. Cows supplemented with OTM had a greater concentration of Cu in follicular fluid than cows supplemented with STM (0.89 vs. 0.77 µg/mL, respectively). In pregnant multiparous cows, expression of receptor transporter protein 4 in peripheral blood leukocytes was 42% greater in the OTM group. Conceptuses of the 2 treatments had 589 differentially expressed transcripts, with many indicating advanced conceptus elongation and greater transcript expression of selenoproteins in the OTM group. In pregnant cows, 24 metabolites were more abundant in the uterine fluid of OTM, including spermidine, sucrose, and cholesterol. In conclusion, replacing STM with OTM caused modest improvements to resumption of ovarian cyclicity and important changes in preimplantation conceptus development, but it did not alter conception risk and pregnancy rate.

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

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

Association of precalving serum NEFA concentrations with postpartum diseases and reproductive performance in multiparous Holstein cows: Cut-off values.

High concentrations of NEFA relative to a defined reference or 'cut-point' values before calving can predict the risk of specific or collective periparturient disease events. A field-based cohort study was conducted to evaluate the value and critical points of serum nonesterified fatty acids (NEFA) at the precalving time to predict the occurrence of postpartum diseases and reproductive performance in dairy cows. Blood samples were taken from 521 high-yielding dairy cows at 1 week (±3days) before calving and NEFA levels were measured. Health and reproduction information of each cow includes dystocia, retained placenta, milk fever, metritis, mastitis, pregnancy in the first insemination and pregnancy in the first two inseminations, and culling in the first 60 days of lactation and milk production. Our results show that there are significant relationships between precalving NEFA with the probability of pregnancy at the first and the first two inseminations after calving. The cows that had NEFA concentrations less than 0.5mmol/L at the last week of pregnancy were 3.51 and 3.15 times more likely to be pregnant at first insemination and the first two inseminations, respectively. Also, our results showed that there are significant relationships between precalving NEFA concentration and the likelihood of dystocia and milk fever. The probability of dystocia and milk fever occurrence were 2.56 and 1.91 times greater in those cows that had NEFA concentrations more than 0.3mmol/L, respectively. The present results indicated that Increasing NEFA during the prepartum period could adversely affect the reproductive efficiency of dairy cows.

Effect of Supplementing Vitamin E, Selenium, Copper, Zinc, and Manganese during the Transition Period on Dairy Cow Reproductive Performance and Immune Function.

The transition dairy cows are challenged by various stresses such as decreased dry matter intake, liver dysfunction, increased inflammation, and oxidative stress, particularly in subtropical regions. These might increase the requirement for vitamin E and trace elements. To examine whether supplementation of vitamin E, selenium or copper, zinc, and manganese complex would help transition dairy cows to achieve greater reproduction performance by overcoming the immune function and postpartum disorders in subtropical Taiwan. A total of 24 Holstein Friesian dairy cows were enrolled in this study and divided into three groups (n = 8 cows/group): treatment 1 supplemented with organic selenium and vitamin E (SeE), treatment 2 supplemented with organic copper, zinc, and manganese complex (CZM) and control (CON). The results showed SeE supplementation improved immune function, reproductive performance, and milk yield, but not negative energy balance status. Supplementation of CZM improved milk yield and energy regulation through antioxidative capacity and immune function, but had no influence on reproductive performance.

Associations of Eliminating Free-Stall Head Lock-Up during Transition Period with Milk Yield, Health, and Reproductive Performance in Multiparous Dairy Cows: A Case Report

The objective of this retrospective case study was to understand the effects of eliminating free-stall lock-up time during 21 days postpartum on milk yield, reproductive performance, and health events at a large dairy herd. A group of 200 cows were selected as the treatment (TRT) group, which did not receive a lock-up time during early lactation, and a separate group of 200 cows served as the control (CON) group, which received on average 2 h/day of lockup time. The TRT group had greater milk yield (mean ± SE) on the third monthly milk test day (33.1 ± 0.75 vs. 29.9 ± 1.22; p = 0.04) and tended to have greater milk yield on the second test day (38.3 ± 1.55 vs. 39.1 ± 0.79; p = 0.06) compared to the CON cows. Milk fat% (mean ± SE) was greater in the TRT group than in the CON group on the first monthly milk test (3.65 ± 0.06 vs. 3.31 ± 0.12, p = 0.01). The TRT group had lower linear somatic cell scores on the first monthly milk test day compared to the CON group (2.6 ± 0.24 vs. 3.2 ± 0.11; p = 0.01). Cows in the TRT group had lower days in milk at first breeding (DIMFB) (66.2 ± 3.7 vs. 76.7 ± 2.9; p = 0.02) and were confirmed pregnant earlier as indicated by smaller days in milk to pregnancy (DIMPREG) (96.9 ± 12.32 vs. 112.1 ± 5.5; p &lt; 0.01). Cows in the TRT group also had fewer incidences of all health events combined (13% vs. 30.5%; p &lt; 0.001), lameness (3% vs. 9.5%; p = 0.01), and mastitis (3% vs. 16%; p &lt; 0.001). We conclude that eliminating the stall lockup may have contributed to the increased milk yield, health, and reproductive performance of dairy cows in this dairy herd. Future prospective cohort studies are needed to further assess the potential effect of eliminating lock up time on cow performance.

Influence of Ovarian Status and Steroid Hormone Concentration on Day of Timed Artificial Insemination (TAI) on the Reproductive Performance of Dairy Cows Inseminated with Sexed Semen.

This study aimed to evaluate the effect of the ovarian status and steroid hormone concentration on the day of TAI on the reproductive performance of dairy cows subjected to estrus synchronization treatment and timed artificial insemination with sexed semen. Seventy-eight cyclic Holstein cows pre-treated with PGF2α-GnRH were divided in two groups-I (Preselect-OvSynch, n = 38) and II (OvSynch+PRID-7-day+eCG, n = 40)-and inseminated with sexed semen. The presence of preovulatory follicle (PF) with or without corpus luteum (CL), the PF diameter, the estradiol (E2) and progesterone (P4) concentrations on the day of TAI, the pregnancy rate (PR) and embryo loss were determined. On the day of TAI, 78.4% of all the pregnant cows presented a PF (mean size 1.80 ± 0.12 cm) without CL, low P4 (0.59 ± 0.28 ng/mL) and high E2 (12.35 ± 2.62 pg/mg) concentrations. The positive correlation between the size of the PF and the level of E2 in the pregnant cows from group II was stronger than that of group I (R = 0.82 vs. R = 0.52, p < 0.05). The pregnancy rate on day 30 (57.5% vs. 36.8%) and day 60 (50% vs. 26.3%; p < 0.05) and the embryo losses (13% vs. 28.5%) showed better effects of treatment in group II. In conclusion, the ovarian status and the steroid hormone concentration on the day of TAI influence the pregnancy rates of dairy cows subjected to estrus synchronization and timed artificial insemination with sexed semen.

DIO1 Gene Polymorphism Is Associated with Thyroid Profiles and Reproductive Performance in Dairy Cows

Thyroid hormones mediate the interaction between the metabolic and reproductive systems, while their metabolism is controlled by different deiodinases. The present study aimed to search for associations of cow genotypes with SNPs in the deiodinase type 1 gene (DIO1) with thyroid profiles and reproductive traits. The blood was sampled from Russian black-and-white cows 2–6 weeks before calving and 1–13 weeks after calving to measure the hormonal levels by ELISA. RT-PCR analysis was performed for known mutations in the bovine DIO1 gene, and a polymorphism at position 13,149 was found. In animals with the CG genotype, the blood concentration of reverse triiodothyronine 6 weeks prepartum was higher and decreased much earlier than in animals with the CC genotype. Furthermore, 1 week after calving, the total triiodothyronine to reverse triiodothyronine ratio in cows with the CG genotype was higher than in cows with the CC genotype. A higher proportion of animals with better values of fertility traits was revealed in the CC group compared to the CG group. Thus, cows with the CC genotype of the DIO1 gene more often have a high reproductive ability, which may be associated with the rT3 profile features during the prepartum and early postpartum periods.