Reproductive Performance Of Dairy Cows Research Articles

Conception Rate and Reproductive Hormone Secretion in Holstein Cows Immunized against Inhibin and Subjected to the Ovsynch Protocol.

Simple SummaryIn recent decades, conception rates in lactating dairy cows have dramatically decreased, and improving the conception rate has become a major challenge in dairy cow reproduction. Various Ovsynch protocols have been developed to aid in the resumption of ovarian follicular activity for timely breeding in post-partum cows. However, the effect of Ovsynch protocols on improving the conception rate is unsatisfactory. In addition, immunization against inhibin was reported to improve the fertility of domestic animals. Thus, a novel reproductive technique combining immunization against inhibin and the widely used Ovsynch protocol was proposed and tested in this study. Our results showed that immunization against inhibin has the potential to improve conception rates in cows, but also compromised luteal function. According to these results, additional luteal-stimulating treatments are suggested to further improve cow fertility based on immunization and the Ovsynch protocol.This study was conducted to investigate the feasibility of improving fertility in dairy cows via immunization against inhibin. Thirty-two cows were divided into Control (n = 11), Low-dose (n = 10) and High-dose (n = 11) groups. The High-dose and Low-dose cows were treated with 1 and 0.5 mg of the inhibin immunogen, respectively. All the cows were subjected to the Ovsynch protocol from the day of antigen administration and were artificially inseminated. Blood samples were serially collected over a 24-day period from the start of the Ovsynch protocol to 14 days after insemination. The results showed that immunization against inhibin dose-dependently increased the plasma concentrations of follicle-stimulating hormone (FSH), estradiol (E2), and activin A, but decreased progesterone (P4) concentrations in the luteal phase. Immunization also increased the plasma interferon (IFN)-τ concentrations in pregnant cows on day 14 after initial insemination. The conception rates in High-dose (45.5%) and Low-dose (40%) cows marginally increased compared to that in Control cows (27.3%), but the increases were not significant (p > 0.05). In conclusion, a single immunization against inhibin has the potential to improve conception rates, despite impaired luteal development. To further improve the reproductive performance of dairy cows, additional luteal-stimulating treatments are suggested in combination with immunization against inhibin and Ovsynch techniques.

Assessment of associations between transition diseases and reproductive performance of dairy cows using survival analysis and decision tree algorithms

This study aimed to evaluate the associations between transition cow conditions and diseases TD with fertility in Holstein cows, and to compare analytic methods for doing so. Kaplan-Meier, Cox proportional hazard, and decision tree models were used to analyze the associations of TD with the pregnancy risk at 120 and 210 DIM from a 1-year cohort with 1946 calvings from one farm. The association between TD and fertility was evaluated as follows: 1 cows with TD whether complicated with another TD or not TD-all, versus healthy cows, and 2 cows with uncomplicated TD TD-single, versus cows with multiple TD TD+; complicated cases, versus healthy cows. The occurrence of twins, milk fever, retained placenta, metritis, ketosis, displaced abomasum, and clinical mastitis were recorded. Using Kaplan-Meier models, in primiparous cows the 120 DIM pregnancy risk was 62% (95% CI: 57–67 %) for healthy animals. This was not significantly different for TD-single (58%; 95% CI: 51–66 %) but was reduced for TD+ (45%; 95% CI: 33–60 %). Among healthy primiparous cows, 80% (95% CI: 75–84 %) were pregnant by 210 DIM, but pregnancy risk at that time was reduced for primiparous cows with TD-single (72%; 95% CI: 65–79 %) and TD+ (62%; 95% CI: 49–75 %). In healthy multiparous cows, the 120 DIM pregnancy risk was 53% (95% CI: 49–56 %), which was reduced for TD-single (36%; 95% CI: 31–42 %) and TD+ (30%; 95% CI: 24–38 %). The 210 DIM pregnancy risk for healthy multiparous cows was 70% (95% CI: 67–72 %), being higher than the 210 DIM pregnancy risk for multiparous cows with TD-single (47%; 95% CI: 42–53 %) or TD+ (46%; 95% CI: 38–54 %). Cows with TD-all presented similar pregnancy risk estimates as for TD + . Cox proportional hazards regressions provided similar magnitudes of effects as the Kaplan-Meier estimates. Survival analysis and decision tree models identified parity as the most influential variable affecting fertility. Both modeling techniques concurred that TD + had a greater effect than TD-single on the probability of pregnancy at 120 and 210 DIM. Decision trees for individual TD identified that displaced abomasum affected fertility at 120 DIM in primiparous while metritis was the most influential TD at 120 and 210 DIM for multiparous cows. The data were too sparse to assess multiple interactions in multivariable Cox proportional hazard models for individual TD. Machine learning helped to explore interactions between individual TD to study their hierarchical effect on fertility, identifying conditional relationships that merit further investigation.

Characterization of Reproductive and Productive Performance of Indigenous and Crossbreed Dairy Cows in Angot District, North Wollo Zone, Ethiopia

The study was undertaken in Angot district, North Wollo Zone, Ethiopia from June 2019 up to March 2020. The objective of the study was of characterize the reproductive and productive performance of indigenous and crossbred dairy cow in Angot district. The participatory rural appraisal (PRA) method was used to generate information during exploratory survey and 100 households were selected for formal survey by using random and purposive sampling technique. The estimated daily milk yield of local and crossbred cow was found to be 1.32±0.11 and 4.62±0.35 liters, respectively. The mean lactation length for local and crossbred dairy cow were reported by the respondents were 9.15±0.63 and 10.8±1.02 months, respectively. The estimated lactation yield of local and crossbred dairy cow in the study area was 365.42±1.96 and 1565.65±11.98 liters, respectively. The average age at first service of local and crossbred dairy heifers in the study area was 34.5±2.71 and 23.41±1.54 months, respectively. The age at first calving (AFC) of the indigenous and crossbred was 45.13±2.31and 34.51±1.94 months, respectively. The average calving interval of local and crossbred dairy cows in the study area were 18.38±1.05 and 15.52±0.97 months, respectively. The estimated average number of calf per lifetime of cow in the study area was 6.21±0.32 (for local) and 9.59±0.49 (for crossbred). The average reproductive lifetime of local and crossbred dairy cows in the study rea ware 16.21±0.27 and 14.07±0.23 years, respectively. The calculated reproductive efficiency of local and crossbred dairy cows were 46% and 77.53%, respectively. In conclusion, the present study indicated that the reproductive performance of dairy cow in the study area was low, thus it calls attention to improve management system to improve the reproductive performance of dairy cows.

Twinning rate is not genetically correlated with production and reproduction traits in Iranian dairy cows

Context Any interruption to the reproductive system can negatively influence animal performance, and suitable animal-management practices should be adopted that will decrease the occurrence of reproductive problems such as may be the case with twinning. Aims The study was designed to estimate genetic parameters for twinning rate (TR) and to estimate genetic correlations between twinning rate and production and reproductive performances in the first lactation of Iranian Holstein cows. Methods The dataset used in this study was collected by the Animal Breeding Center of Iran during 1991–2013 and consisted of 273742 records of calving type (singleton or twin), 435742 records of 305-day milk yield, 424175 records of milk fat percentage, 253901 records of milk protein percentage, 251558 records of first calving interval, and 153632 records of number of days to first service. A single Gibbs sampling chain with 500000 rounds was generated to run linear and threshold animal models. Key results Posterior mean estimates of heritabilities for traits were: TR 0.0028, milk yield 0.28, milk fat percentage 0.33, milk protein percentage 0.38, first calving interval 0.064, and days to first service 0.061. Genetic correlations between TR and performance traits were negligible and varied from –0.08 (between TR and milk yield) to 0.04 (between TR and protein percentage). Conclusions Diminishing TR by genetic selection is a slow task owing to its low heritability. Negligible genetic correlation between TR and performance traits suggests that selection for decreased TR would not cause a significant decrease in milk production, nor is it likely to have a negative impact on the reproductive performance of dairy cows. Implications Dairy cattle breeders should follow genetic selection programs, especially for milk-production traits, without concern for an increase in twinning rate.

Effects of increasing lipopolysaccharide concentrations on in vitro developmental competence of ovine oocytes.

Although a considerable number of studies have investigated the effects of lipopolysaccharide (LPS) on the reproductive performance of dairy cows, the response of ovine oocytes to LPS during their in vitro maturation and development is not well defined yet. Ewe’s ovaries were obtained from a slaughterhouse, the oocytes were collected and matured in the presence of increasing concentrations (0, 0.01, 0.1, 1 and 10 µg/mL) of LPS in order to evaluate the meiotic maturation by measuring the proportion of oocytes reaching the MII stage. The concentration of intracellular glutathione (GSH) was measured in oocytes following maturation in vitro. In addition, concentrations of selected metabolites including glucose, pyruvate, lactate and glutamine were quantified in the medium following maturation. A number of treated matured oocytes along with the control group were subsequently fertilized using frozen semen and assessed for the rate of cleavage and for the proportion reaching the blastocyst stage. The number of oocytes in MII stage was significantly reduced in response to the increasing concentrations of LPS (77.83%, 70.64%, 68.86%, 66.32%, respectively, in case of 0.01, 0.1, 1 and 10 µg/mL LPS when compared to the control group, 76.34%; P<0.05). There were no differences neither in the intracellular concentration of GSH in the oocytes nor in case of the metabolites in the maturation medium. Although the rate of cleaved oocytes was not affected by increasing levels of LPS, the blastocyst rate was reduced in a dose dependent manner (36.69%, 34.21%, 30.35%, 17.27% and 14.03% for the control, 0.01, 0.1, 1 and 10 µg/mL LPS, respectively (P<0.05). These results demonstrate that the developmental competence of ovine oocytes may be affected detrimentally by LPS and such deleterious effects could be related to the maturation process.

Combined effect of mastitis and parity on pregnancy loss in lactating Holstein cows

The main objective of this study was to examine the combined effect of mastitis and parity on pregnancy loss (PL) in lactating Holstein cows. A secondary objective was to estimate the cost of mastitis including that of PL attributable to mastitis. A total of 1,774 lactation periods from 1,047 Holstein cows with different parities from one dairy farm were included in a matched case-control study. All study cows were diagnosed pregnant by transrectal ultrasonography on day 33 after timed artificial insemination (TAI). Case cows (n = 222 lactations) were those later diagnosed non-pregnant by transrectal palpation on day 47 or 75 after TAI. Control cows (n = 1,552 lactations) were those confirmed pregnant by transrectal palpation on day 75 after TAI. Case cows were matched with eligible controls according to year of calving and calving-to-conception interval (CCI) ± 3 days. Cows with different parities were classified as exposed to subclinical mastitis (somatic cell score (SCS) > 4.5 in at least one Dairy Herd Improvement Association (DHIA) test day) or clinical mastitis (with or without evidence of subclinical mastitis) during two exposure periods: 1–42 days before breeding or 1–75 days during gestation (1 to PL diagnosis day in case cows, or 1–75 day in control cows). Conditional logistic regression was used to model the odds of PL as a function of previous exposure to mastitis in different parities. Cost of PL attributable to mastitis ($/case) among cows with mastitis was estimated based on attributable risk calculated in the epidemiologic analysis. We observed a higher than expected combined effect between exposure to mastitis (subclinical or clinical) before breeding and parity 3 or ≥ 4, and during gestation and parity ≥ 4 on PL. The cost of PL attributable to mastitis was highest ($196/case) in cows in parity ≥ 4 affected with clinical mastitis during gestation. Overall, study results indicate the impact of mastitis on PL is higher in older cows (parity ≥ 3). Dairy farmers and attending veterinarians can consider the combined effect of mastitis and parity when evaluating causes for PL and strategies for optimizing reproductive performance in dairy cows.

Productive Response and Reproductive Performance of Dairy Cows Subjected to Different Feeding Systems

Fifty Holstein cows (2.6 ± 1.0 lactations) in early lactation (52.6 ± 16.4 days in milk) calved in autumn and producing 34.3 (±4.4) kg milk per cow·day-1 were randomly assigned for 27 weeks to one of two treatments (feeding systems) in 10 groups (pens) of 5 animals each (5 groups/treatment). The confined treatment was a total mixed ration (TMR_100) whereas the supplemented grazing system was defined by a partially mixed ration (PMR_75) with 75% TMR and 25% oat pasture (Avena sativa L.) during the autum-winter (Period I) and alfalfa pasture (Medicago sativa L.) plus concentrate (7.0 kg per cow·day-1) (P + C) during the next spring (Period II). Milk production was daily and individually recorded throughout the trial while the chemical composition of milk was measured on individual samples every 2 weeks. Live weight (LW) and body condition score (BCS) using a scale of 1 to 5 were recorded every 3 weeks after the morning milking. Simultaneously, blood samples were taken for determinations of glucose, urea, non-esterified fatty acids (NEFA), insulin, somatotrophin (GH) and somatomedin C (IGF-I). Total DM intake was measured using the difference method four times per repetition in the months of July, August, September and October. The experimental herd was inseminated at fixed time at the start of the service (May-July) and on the return with estrus detection. The diagnosis of pregnancy was made by transrectal ultrasonography at 30 and 60 days after the start of the service. The productive data were analyzed according to a model with repeated observations in time adjusted by covariate with 2 periods and using the animal as the experimental unit. Data of DM intake were analyzed using ANOVA for 2 treatments with 5 repetitions. Cows from the TMR_100 group produced more milk (kg·cow-1·day-1) during Period I (33.7 vs. 32.3) and Period II (28.8 vs. 27.8) (P ·cow-1·day-1) in Periods I (1.33 vs. 1.24) and II (1.10 vs. 0.92) and for milk protein (1.19 vs. 1.13 and 0.99 vs. 0.93). The lower energy intake of grazing cows (45.0 vs. 43.1 and 40.9 vs. 38.9 Mcal per cow·day-1 for TMR_100 vs. PMR_75 and TMR_100 vs. P + C) coupled to the extra energy cost associated with grazing activity would explain the difference in milk production. Milk protein content (%) resulted higher (P kg·cow-1·day-1) in the cows of the TMR_100 group in both periods (0.69 vs. 0.34 and 0.49 vs. -0.22) was consistent with the increase in the plasmatic levels of glucose and IGF-I and the reduction in the circulating levels of GH, but not with the lack of increases in plasma insulin concentration or decreases in circulating levels of NEFA, parameters that were not affected by treatments. Despite the positive effects of TMR_100 on parameters linked to energy balance, no significant differences were detected in any of the reproductive parameters evaluated and the final rate of pregnancy was 80.0 and 91.3% for the confined and grazing system with supplementation respectively. Free milk liters over feeding costs were higher in the grazing system with supplementation compared to the confined system (18.5 vs. 15.5 l, respectively). The results indicate that the grazing system with supplementation can be economically competitive compared to the confined system of milk production.

IMPACT OF INTRAVAGINAL PROBIOTICS INOCULATION ON REPRODUCTIVE PERFORMANCE OF HOLSTEIN DAIRY CATTLE DURING TRANSITION PERIOD

In this study we tested the hypothesis that intravaginal infusions of lactic acid bacteria (LAB) around calving would improve uterine involution and reproductive performance of dairy cows. The probiotic culture used in this study was a mixture of 2 LAB strains isolated previously from the vaginal tract of healthy pregnant heifers. Forty pregnant 2nd lactation dairy cows 2 wk before the expected day of calving were assigned to one of 2 groups, first group was the control group (C) receiving 1 mL of media only, and the 2nd group was the treated group (T) receiving 1 mL of media enriched with probiotic bacteria at 1010 to 1012 cfu / treatment. Intravaginal infusions were performed once during wk −2, −1, +1, +2, +3, and +4 relative to parturition with probiotic bacteria. All cows were observed for reproductive performance and reproductive diseases until next conception using ultrasonography. The incidence of uterine infections in the multiparous cows were measured. Days open, conception rate at 1st, 2nd and 3rd insemination and repeat breeders (%) were calculated. Incidence of purulent and foul-smelling discharges on +1, +2, +3 and +4 wk relative to parturition and numbers of cows in the clean-up program were measured, cervix diameters (C.D) and uterine horn diameters (U.H.D) were measured at days (22-29) and days (38-45) postpartum. Ovarian structures and endometritis were determined. Results revealed that uterine and cervical involution of postpartum dairy cows were earlier in cows treated with LAB. Cows showed purulent and fowl smelling discharges are fewer in number in treated group than control, also data showed that percentage of cows in the cleanup program was higher in the control group (40%) than in the treated group (20%). The averaged insemination number per conception was lesser in the treated group (2.55) than control (4). The conception rate at 1st insemination and 3rd insemination was higher in the treated group (35%, 20%) than in control one (25%, 10%), and the %of repeated breeder cows was lower in the treated group (30%) than control (40%), finally days open in the treated group (116.4) was much lower than in the control (154.72). Therefore it can be conclude that, intravaginal treatment of transition dairy cows with a mixture of lactic acid bacteria (LAB) could improve uterine involution, lower the incidence rates of uterine infections, and improve the reproductive performance.

Quantifying the effects of mastitis on the reproductive performance of dairy cows: A meta-analysis

The objective of this study was to conduct a meta-analysis to quantitatively characterize the effects of mastitis on the reproductive performance of dairy cows as well as to identify factors that interact with this relationship. A total of 29 publications were identified that contributed 24, 41, 27, 38, and 13 trial results to the meta-analysis of how mastitis is related to time to first service (TFS), days open (DO), services per conception (SPC), pregnancies per insemination at first service (FSP/AI) and pregnancy loss (PL), respectively. The meta-analyses were conducted using multilevel linear mixed-effects models. Overall, high levels of heterogeneity were present and meta-regression models only explained a small amount of heterogeneity. Results suggest that cows with mastitis pre-first insemination experience, on average, an additional 13.29 d to first service [95% confidence interval (CI): 6.64, 19.95] when compared with cows with no mastitis in the same time period. Moreover, in relation to cows with no mastitis in the same time period, 22.34 additional DO (95% CI: 12.89, 31.79) were estimated, on average, for cows with clinical mastitis at pre-insemination leading to conception. Additionally, 32.41 added DO (95% CI: 20.58, 44.25) were estimated, on average, for cows with clinical mastitis at pre- or post-insemination leading to conception compared with cows with no mastitis in the same time period. Finally, 20.03 additional DO (95% CI: 3.11, 36.95) were estimated, on average, for cows with subclinical mastitis pre- or post-insemination leading to conception compared with cows with no mastitis in the same time period. Effect size estimates from the meta-regression models for SPC, in relation to cows with no mastitis in the same time period, suggest that, on average, SPC increases by 0.46 inseminations (95% CI: 0.30, 0.62) for a cow experiencing mastitis pre-insemination leading to conception. When mastitis occurs either pre- or post-insemination leading to conception, SPC is expected to increase, on average, by 0.72 inseminations (95% CI: 0.48, 0.95) compared with cows with no mastitis in the same time period. The estimated effect sizes for FSP/AI suggest a risk ratio of conceiving at first insemination of 0.90 (95% CI: 0.82, 0.99) for cows with mastitis diagnosed pre-first insemination with respect to cows with no mastitis in the same time period, and a risk ratio of 0.79 (95% CI: 0.72, 0.86) for cows diagnosed with mastitis either pre- or post-first insemination with respect to cows with no mastitis in the same time period. Publication bias was identified in 4 of the meta-analysis models (TFS, DO, SPC, and FSCR), but no influential trials were identified in any models; the reliability of the meta-analysis results should be interpreted carefully keeping these limitations in mind. Further meta-regression analysis would be valuable as additional studies are published that report other potential sources of heterogeneity.

The factors associated with postpartum body condition score change and its relationship with serum analytes, milk production and reproductive performance in dairy cows

Objectives were to (1) identify factors associated with postpartum body condition (BCS) maintenance/gain, (2) determine the optimum pre-calving BCS predictive of postpartum BCS maintenance/gain, and (3) evaluate the relationship between postpartum BCS change categories, serum analytes and performance in dairy cows. The BCS were determined in 271 primiparous and 640 multiparous cows from 11 dairy herds in Alberta, Canada at (mean ± SD) 9.0 ± 2.3 d pre-calving and at 34.6 ± 4.0 d post-calving, using a 5-point scale with 0.25 increments. Cows were grouped into BCS change categories according to BCS change between post- and pre-calving as follows: lost ≥ 0.75 units (extreme loss; EL; n = 343), lost either 0.25 or 0.50 units (moderate loss; ML; n = 390), no change in BCS (maintained; M; n = 104), or gained ≥ 0.25 units (gained; G; n = 74). In a subset of 178 cows, the concentrations of glucose, beta-hydroxybutyrate, non-esterified fatty acids, urea, cholesterol, haptoglobin and aspartate aminotransferase were measured in serum at 9.0 ± 2.3 d pre-calving and at 8.2 ± 3.7 d post-calving.The proportion of cows grouped into EL, ML, M and G categories were 38, 43, 11 and 8%, respectively. Pre-calving BCS, season of calving and sickness were identified as factors associated with BCS maintenance/gain. The optimum pre-calving BCS predictive of postpartum BCS maintenance/gain was 3.25 for primiparous cows and 3.00 for multiparous cows. Mean serum concentration of beta-hydroxybutyrate, urea, cholesterol and haptoglobin did not differ among BCS change categories. However, G cows tended to have greater mean serum concentration of glucose compared with ML cows, and mean serum concentration of aspartate aminotransferase tended to be greater for EL cows compared with other BCS change categories. Mean serum concentration of non-esterified fatty acids was greater post-calving for EL cows compared with other BCS change categories. Milk yield by 25 and 90 days in milk (DIM) did not differ among BCS change categories; however, peak and 305-d mature equivalent milk yields were greater for EL compared with G cows. Overall, EL cows had reduced fertility compared with other BCS change categories, including a smaller proportion of cows with a corpus luteum by 35 DIM, reduced pregnancy to first AI and pregnancy by 150 DIM, and reduced hazard ratio of pregnancy risk up to 250 DIM. In summary, EL cows had reduced fertility compared with other BCS change categories and increased milk yield compared with G cows. Ensuring cows calve at an appropriate BCS to promote BCS maintenance, or only moderate loss, will improve fertility without sacrificing milk yield.

Vegetable Oils Rich in Polyunsaturated Fatty Acids Supplementation of Dairy Cows’ Diets: Effects on Productive and Reproductive Performance

Simple SummaryRuminants milk contains some bioactive lipids that have a beneficial effect on human health. The present study aimed to evaluate the benefit of incorporating polyunsaturated fatty acids rich vegetable oils on productive and reproductive performance of dairy cows. The results show that including polyunsaturated fatty acids and rich vegetable oils in rations of dairy cows improve the nutritional profile of milk and some reproductive parameters. Ruminant milk often has a negative image for health because of its fat content and its composition. A way to improve the nutritional profile of the milk is to supplement dairy cows’ diets with polyunsaturated vegetable oils, which makes it healthier for the consumer and improves the commercial value of the milk in view of the continued decline in fertility among dairy cows. The possibility of supplementing the diet with vegetable oils rich in polyunsaturated fatty acids as a means of improving reproductive performance has considerable interest for dairy producers.The aim of this study was to determine how polyunsaturated fatty acids (PUFA) supplementation can affect the productive and reproductive performance in dairy cows subjected to a fixed-time artificial insemination (TAI) protocol under farm conditions. One hundred and ninety-eight Holstein non-pregnant cows were used. Treatments consisted of a control diet (CON), without added oil, and two diets supplemented with either 2.3% soybean oil (SOY) or 2.3% linseed oil (LIN) as dry matter. The diets were formulated to be isoenergetic and isoproteic. Dry matter intake and milk yield were similar among treatments (p > 0.05). Both the percentage of fat (p = 0.011) and protein (p = 0.022) were higher in milk from animals not fed with oil (CON). The greatest saturated fatty acid (SFA) concentration (p < 0.0001) was observed in milk from cows fed the control diet, without added oil. The monounsaturated fatty acids (MUFA), PUFA, and the n-3 PUFA content was higher (p < 0.0001) in the milk from animals fed with oil with respect to the control treatment. The C18:2 cis-9, trans-11 in the milk of animals fed with oil supplements was significantly higher (p < 0.0001) than in that of the control group. Animals supplemented with linseed oil tended to show higher plasma progesterone level (p = 0.09) and a higher number of pregnant cows on the first artificial insemination (p = 0.07). These animals tended to reduce the number of TAI (p = 0.08). In brief, results showed that vegetable oils rich in PUFA supplementation considerably improve the nutritional profile of milk. PUFA n-3 supplementation slightly improves some reproductive parameters in dairy cows subjected to the fixed-time artificial insemination (TAI) protocol.

Postpartum Uterine Bacterial Contamination without Clinical signs in Rela-tion to Reproductive Performance in Dairy Cows

The study was performed to find out the relation between the uterine bacterial contaminations without clinical signs and postpartum (PP) reproductive performance of dairy cows. So that, uterine bacterial samples from postpartum dairy cows total (n = 44) were taken at 3rd, 15th and 30th day, and the bacterial count and score were applied. The animals were grouped to low, medium and high uterine bacterial contamination (15, 15, and 14 cows for each group respectively) according to score. Results revealed that uterine bacterial score (UBS) was decreased by the time in 3rd, 15th and 30th day (PP) for Low bacterial contamination group (5.73, 2.80, and 1.20 respectively), for Medium bacterial contamination group (7.80, 2.73, and 1.47 respectively), and for High bacterial contamination group (9.29, 6.57, and 2.21 respectively). Also, it revealed that there was a significant increase (P&lt;0.05) in the duration of lochia in High than Low and Medium bacterial contamination groups. At 3rd day (PP), uterine location in all cows was represented in the abdominal cavity, but at15th day (PP), uterine involution as reaching to its normal non pregnant position in pelvic cavity was delayed in High (50%) than Low (80 %,) and Medium (53.30%) UBS groups. Moreover, at 30th day, uterine location in all cows was represented in pelvic cavity. The first estrus (PP) was significantly shorter in Medium, Low than High UBS groups. The number of services per conception showed a significant increase in High than in Low and Medium UBS groups. Also, at the 90th day (PP), the conception rate was lower in High UBS group than Low UBS group and Medium UBS group. We conclude that there was a relation between postpartum uterine bacterial contamination without clinical signs especially high contamination and reproductive performance in cows.

Uterine Involution and Reproductive Performance in Dairy Cows with Metabolic Diseases.

Simple SummaryMetabolic diseases, such as hypocalcemia, ketosis and lipomobilization, cause financial losses in dairy farms, mainly due to the costs of treatment, milk discharges and decreased milk production of diseased animals. Four groups of dairy cows were selected. The uterine involution of the animals was evaluated by palpation and transrectal ultrasonography during the postpartum period. In conclusion, cows with metabolic diseases had a delayed uterine involution when compared to animals without metabolic diseases.The aim of this study was to investigate the effects of metabolic diseases on uterine involution and reproductive performance during the postpartum period. Multiparous Holstein dairy cows (n = 50) were divided into four groups based on whether they were healthy (n = 14), or had lipomobilization (n = 14), hypocalcemia (n = 11), and hyperketonemia (n = 11). Transrectal palpation and transrectal B-Mode sonography were carried out on days 7, 14, 21, 30, 45 and 60 after parturition. Cows with metabolic disease had a greater (p < 0.05) uterine size as assessed transrectally compared with cows without metabolic disease. Sonographic measurements revealed a greater (p < 0.05) horn diameter and endometrial thickness in cows of the metabolic disease groups than in the healthy cows. Metabolic disease affected (p < 0.05) the milk yield, percentage of service per pregnancy, days to first ovulation and days open. In conclusion, metabolic disease affected the uterine involution and fertility during the postpartum period.

Effect of Milking Frequency on Body Condition Score, Somatic Cell Count, and Reproductive Performance of Dairy Cows Milked by An Automatic Milking System

The objective of this study was to determine the effect of milking frequency using an Automatic Milking System (AMS) on body condition scores (BCS), somatic cell count (SCC), and reproductive performance of Holstein cows. The study was conducted in Hiroshima University Farm. Eight multiparous cows and four primiparous cows were divided into two treatments of groups (2 and 4 times milking frequency). Cows were fed by Partial Mixed Ration (PMR) ad libitum and concentrate diet (5-8 kg) at every milking. The PMR consisted of Italian ryegrass silage 35% dry matter (DM), oat hay (8% DM), alfalfa hay (8% DM), pellet bit pulp (8% DM), formula feed (39% DM), minerals and vitamin. The PMR nutrients contents were 13.6% crude protein (CP) and 70% total digestible nutrient (TDN), while concentrate contained 20.6% CP and 82.4% TDN. On days 20, 35, and 50 postpartum, BCS was observed, and milk samples were collected for SCC analysis. Reproductive performance data collected were S/C, calving interval, and postpartum mating. The MIXED model for repeated measures (SAS 2004) was used for testing the difference in BCS and SCC. Significance was declared at P < 0.05, and tendency at P < 0.10. The research showed that no difference on BCS and SCC between 2 and 4 times milking by AMS, but the probability of occurrence of high SCC (> 100,000) was lower for four times milking cows than 2 times milking cows (6% vs 59%). The effect of milking frequency did not show any difference on S/C, calving interval, and postpartum mating. Increasing milking frequency may positively affect on SCC without any effects on BCS and reproductive performance in this experiment.

Inferior fertility and higher concentrations of anti-Müllerian hormone in dairy cows with longer anogenital distance

Anogenital distance (AGD), which is an indicator of prenatal androgen exposure, has been reported to have high variability and negative association with fertility in dairy cows. Prenatal exposure to androgens could influence the development of primordial follicles and size of ovarian reserve, which is related to reproduction. However, the relationship between AGD and size of ovarian reserve has not been studied. Therefore, the present study was conducted to determine the association between AGD and circulating anti-Müllerian hormone (AMH), as an indirect marker of ovarian reserve, and to evaluate serum AMH concentration and reproductive performance in dairy cows with short and long AGD. Anogenital distance was measured 28 to 32 d postpartum, and based on the median of AGD, cows were divided into 2 subsets including short (n = 43) and long (n = 43) AGD groups. Afterward, serum AMH was evaluated on the day of estrus in cows that were estrus-synchronized. Furthermore, reproductive data of dairy cows during the previous lactation period were collected from the herd database. Concentrations of serum AMH tended to be positively associated with length of AGD, and there was a tendency for higher serum AMH concentrations in the long (634.89 ± 74.52 pg/mL) than short (451.39 ± 45.92 pg/mL) AGD group (0.05 <P ≤ 0.10). There was a tendency for more days to first service, lower first service conception rate, and higher proportion of repeat breeders in long (99.95 ± 5.34 d, 30.23% and 32.56%, respectively) than short (89.07 ± 4.97 d, 48.84% and 16.28%, respectively) AGD cows (0.05 <P ≤ 0.10). Services per conception did not differ between short (2.30 ± 0.27) and long (2.93 ± 0.29) AGD cows (P > 0.05). Calving to conception interval was prolonged in long (194.30 ± 17.12 d) than short (147.14 ± 13.11 d) AGD cows (P ≤ 0.05). In conclusion, the present study revealed elevated serum AMH concentrations and poor reproductive performance in cows with longer AGD compared with cows with shorter AGD.

Association of postpartum diseases occurring within 60 days after calving with productivity and reproductive performance in dairy cows in Fukuoka: A cow-level, retrospective cohort study.

Peripartum disorders in dairy cows negatively influence their productivity and reproductive performance. However, only a few reports have clearly indicated the influence of such disorders on the productivity and reproductive performance at a local-area or cow-level in Japan. This study aimed to elucidate the influence of diseases occurring within 60 days after calving on subsequent productivity and reproductive performance. Accordingly, a wide-area database on dairy production was used for epidemiological analysis; subsequently, multivariable analysis was performed to investigate the association of such diseases with productivity or reproductive performance in 6,545 cows from 178 farms in Fukuoka. We used 305-day energy-corrected milk (305 ECM) as an index of productivity and conception and culling as indices of reproductive performance. With regard to causality, mixed-effects model was used for analyzing the association between disease and productivity, and Cox proportional hazard model was used for analyzing the association between disease and reproductive performance. Compared to the disease absence group, the disease presence group demonstrated significantly lower 305 ECM [−154 kg; 95% confidence interval (CI), −229 to −79] and risk of pregnancy [hazard ratio (HR), 0.85; 95% CI, 0.80–0.91] and higher risk of culling (HR, 1.36; 95% CI, 1.17–1.59). These results indicate that, in Fukuoka, dairy cows affected by diseases within 60 days after calving exhibit lower productivity and reproductive performance. Therefore, proper dairy cow management during the peripartum period to prevent diseases during early lactation may maintain or improve productivity.

Effect of prostaglandin F2α and GnRH administration at the time of artificial insemination on reproductive performance of dairy cows.

The present study aimed to determine the effect of administrating prostaglandin F2α (PGF2α) and GnRH at the time of artificial insemination (AI) on the pregnancy per artificial insemination (P/AI) and the pregnancy survival rate of dairy cows. A number of 830 lactating Holstein cows were randomly divided into four groups. Cows in group 1 (n=200) treated with 150 µg d-cloprostenol. In group 2 (n=212), cows received 10 µg buserelin acetate, and group 3 (n=205) was treated with both 150 µg d-cloprostenol and 10 µg buserelin acetate. In addition, 213 cows were assigned as control group which received normal saline as placebo (group 4). To measure progesterone, milk samples were collected at the insemination day and five days later. Pregnancy diagnosis was performed 28 and 60 days after the insemination, and the size and number of corpus luteum (CL) and twin pregnancies were recorded. Hormone therapies had no effect on the P/AI, pregnancy survival rate, and the size and number of CL. The P/AI ratio in groups 1, 2, 3 and 4 were 38.50%, 42.92%, 41.46% and 40.84%, and the pregnancy survival rates in groups 1, 2, 3 and 4 were 84.42%, 86.81%, 88.23% and 83.91%, respectively. The probability of a twin pregnancy was significantly higher in group 1 (15.58%) than other groups. There was no significant difference between groups in terms of the offspring gender. In conclusion, the administration of d-cloprostenol or buserelin acetate at the time of AI had no effect on P/AI and pregnancy survival rate in dairy cattle under no heat stress condition, while the administration of d-cloprostenol increased the probability of twin pregnancies.

Associations of Puerperal Metritis with Serum Metabolites, Uterine Health, Milk Yield, and Reproductive Performance in Dairy Cows

Associations of Puerperal Metritis with Serum Metabolites, Uterine Health, Milk Yield, and Reproductive Performance in Dairy Cows

Relationships between Calving Season and the Incidence of Postpartum Disorders, Milk Yield, and Reproductive Performance in Dairy Cows

Relationships between Calving Season and the Incidence of Postpartum Disorders, Milk Yield, and Reproductive Performance in Dairy Cows

Effects of nutrition and genetics on fertility in dairy cows.

Optimal reproductive function in dairy cattle is mandatory to maximise profits. Dairy production has progressively improved milk yields, but, until recently, the trend in reproductive performance has been the opposite. Nutrition, genetics, and epigenetics are important aspects affecting the reproductive performance of dairy cows. In terms of nutrition, the field has commonly fed high-energy diets to dairy cows during the 3 weeks before calving in an attempt to minimise postpartum metabolic upsets. However, in the recent years it has become clear that feeding high-energy diets during the dry period, especially as calving approaches, may be detrimental to cow health, or at least unnecessary because cows, at that time, have low energy requirements and sufficient intake capacity. After calving, dairy cows commonly experience a period of negative energy balance (NEB) characterised by low blood glucose and high non-esterified fatty acid (NEFA) concentrations. This has both direct and indirect effects on oocyte quality and survival. When oocytes are forced to depend highly on the use of energy resources derived from body reserves, mainly NEFA, their development is compromised due to a modification in mitochondrial β-oxidation. Furthermore, the indirect effect of NEB on reproduction is mediated by a hormonal (both metabolic and reproductive) environment. Some authors have attempted to overcome the NEB by providing the oocyte with external sources of energy via dietary fat. Conversely, fertility is affected by a large number of genes, each with small individual effects, and thus it is unlikely that the decline in reproductive function has been directly caused by genetic selection for milk yield per se. It is more likely that the decline is the consequence of a combination of homeorhetic mechanisms (giving priority to milk over other functions) and increased metabolic pressure (due to a shortage of nutrients) with increasing milk yields. Nevertheless, genetics is an important component of reproductive efficiency, and the incorporation of genomic information is allowing the detection of genetic defects, degree of inbreeding and specific single nucleotide polymorphisms directly associated with reproduction, providing pivotal information for genetic selection programs. Furthermore, focusing on improving bull fertility in gene selection programs may represent an interesting opportunity. Conversely, the reproductive function of a given cow depends on the interaction between her genetic background and her environment, which ultimately modulates gene expression. Among the mechanisms modulating gene expression, microRNAs (miRNAs) and epigenetics seem to be most relevant. Several miRNAs have been described to play active roles in both ovarian and testicular function, and epigenetic effects have been described as a consequence of the nutrient supply and hormonal signals to which the offspring was exposed at specific stages during development. For example, there are differences in the epigenome of cows born to heifers and those born to cows, and this epigenome seems to be sensitive to the availability of methyl donor compounds of the dam. Lastly, recent studies in other species have shown the relevance of paternal epigenetic marks, but this aspect has been, until now, largely overlooked in dairy cattle.