Number Of Inseminations Research Articles

Vertical and Horizontal Transmission of Neosporosis in Three Consecutive Pregnancies of Naturally Infected Pregnant Cows and the Effect of Vaccination on Abortion Rates

Background/Objectives:Neosporosis is a major cause of abortions in cattle worldwide. Primary results showed that the administration of a live attenuated vaccine during the mid-pregnancy stage of naturally infected cows may assist in preventing abortions. In this study, the effect of vaccination was evaluated in five dairy herds, with a follow-up of three consecutive pregnancies and re-vaccination during the subsequent pregnancies of some of the cows. Methods: A total of 1059 heifers were serologically tested during their first pregnancy, and 260 and 21 of them were re-tested during their second and third pregnancies. Vaccination was administered to 193 of 420 cows with antibody titers of 1:800 or higher, and 23 of them were re-vaccinated. Data were collected regarding the outcome of each pregnancy, the number of inseminations required and removal from the herd. Vertical transmission was evaluated in 136 pre-colostral calves born from 29 vaccinated and 107 unvaccinated dams. Results: The total seroprevalence using a cutoff titer of 1:800 was 33.1, 36.5 and 85.7% during the three consecutive pregnancies. The antibody titers of individual cows fluctuated over time. Abortion rates and the rate of removal from the herd were significantly higher in seropositive cows. The rate of vertical transmission increased in correlation with the dam’s antibody titer. Immunization resulted in lower abortion rates at two of the farms. Vaccine efficacy ranged from a negative effect to 54% at different farms, with an overall efficacy of 10.4%. The effect of vaccination on abortions, reproductive performance, antibody titers, vertical transmission and removal from the herd was not significant. Conclusions: These results demonstrate varying vaccine efficacies among farms and suggest that neosporosis is a multifactorial disease that cannot be solely controlled by vaccination.

Reproductive traits and economic aspects on dairy cattle.

This study aimed to characterize the reproductive parameters and economic indicators of dairy farms. Data were from technical assistance of the Programa de Desenvolvimento em Pecuária Leiteira (PDPL-UFV) including 26 farms, from September 2022 to August 2023, comprising an entire production cycle. The following economic indicators were selected as dependent variables: Unit Net Margin (UNM), Operating Profitability (OP) and Rate of Return on Capital (RRC). Reproductive parameters were used as explanatory variables in multiple linear regression analysis. A stepwise selection was performed and only variables significant at p < 0.10 were kept in the final model. Pregnancy rate of cows, number of inseminations per pregnant heifer, and replacement rate were the reproductive parameters with the greatest effect on the evaluated economic indices. The UNM and OP were positively affected by pregnancy rate of cows and number of inseminations per pregnant heifer, but replacement rate negatively affected both indices. Only the pregnancy rate of cows showed a significant and positive effect on RRC. Results suggest that the economic viability of a dairy farm is not only associated with cutting costs such as reducing the number of inseminations in heifers, or increasing revenue by selling animals, which increases the replacement rate.

Evaluation of Fertility Parameters and Nutrition-Fertility Relationship in Dairy Cattle Farms in Ereğli District of Konya Province

In this study, 49 dairy farms (total cow number: 2234) in Ereğli district of Konya province were surveyed using a face-to-face questionnaire to obtain information about the dairy farms animal nutrition, care, and reproductive efficiency of dairy farms. The research material consisted of the data obtained from breeders through the questionnaire. The mean values of the calving interval and number of days open were 374.73 (days), and 95.61 (days), and the number of artificial inseminations and natural mating per pregnancy were 2.27 and 1.7 respectively. In our study, the mean duration of the first postpartum estrus was found to be 44.30 days and 71.42% of the dairy farms had estrous between 20-45 days. It was observed that 95.9% of the dairy cattle owners thought that the energy level of the ration, 85.7% of the protein level of the ration, and 73.5% of the vitamin-mineral supplementation were effective on fertility. It was observed that only 10.2% of dairy cattle owners used pasture for nutritional purposes and 89.8% of those who used pasture thought that pasture was inadequate. It is also observed that the breeders in the region are aware of the nutritional conditions. It is also observed that the dairy farmers in the area are aware of the nutritional conditions. In conclusion, it is observed that the dairy cattle farms in the Ereğli district of Konya province are not effective in terms of the reproductive parameters evaluated in the study. Also, these results regarding grazing clearly show that grazing is insufficient in terms of animal nutrition.

Analysis of influencing factors of clinical pregnancy rate in second cycle intrauterine insemination.

To explore the factors influencing the clinical pregnancy rate in the Reproductive Center of the Affiliated Hospital of North Sichuan Medical College in the second cycle, a retrospective analysis of the clinical data of 175 patients who underwent the second cycle of intrauterine insemination (175 cycles) from July 2019 to July 2022 was performed. According to whether the patients reached clinical pregnancy, they were divided into the pregnant group (32 cycles) and non-pregnant group (143 cycles). The age, infertility years, infertility factors, infertility type, number of sinus follicles, intimal thickness, intimal type, basal follicle-stimulating hormone, basal luteinizing hormone, basal estradiol, stimulation regimen, season, body mass index, and male semen quality were statistically analyzed between the 2 groups. The number of intrauterine insemination (IUI) in the second cycle was 175, and the clinical pregnancy rate was 18.3% (32/175). The age of the pregnant group was lower than that of the non-pregnant group [(26.7 ± 1.07) vs (30.56 ± 0.51), P = .05]. The clinical pregnancy rate in patients aged ≤30 years was significantly higher than that in patients aged > 30 years [28.6% vs 7.1%, P < .05]. Among infertility factors, the pregnancy rate of patients who underwent IUI due to female factors was significantly higher than that of male factors, combined factors (both male and female), and unexplained infertility, and the differences were statistically significant [37.1% vs 22.4%, 18.2%, 3.2%, P < .05]. In multivariate logistic regression analysis, age and infertility factors were independent influencing factors of clinical pregnancy rate in the second cycle of IUI. In, while in artificial insemination, female age and infertility factors were important factors affecting the clinical pregnancy rate of the second cycle of IUI. If the outcome of the first cycle is not pregnant, the female age is <30 years, infertility is the female factor, and the second cycle of IUI can be considered.

Influence of different concentrations of milk urea nitrogen on the reproductive performance of Holstein cows.

The purpose of this study was to assess how various MUN levels affected the reproductive performance traits of Iranian Holsteins. The dataset used in this study included reproduction performance records for 16,000 Holstein cows and was gathered by the Animal Breeding Center and Promotion of Animal Products of Iran on 30 large dairy herds during 2018-2021. The MUN concentrations were grouped into four classes: [Formula: see text] mg/dL (MUN1), [Formula: see text] mg/dL (MUN2), [Formula: see text] mg/dL (MUN3), and [Formula: see text] mg/dL (MUN4). The study took into account various reproductive and fertility traits, such as the number of inseminations per conception (NINS), the percentage of pregnant cows till 120 days in milk (PP120), the calving interval (CI), the days open (DO), the days from calving to the first service (DCFS), the first service conception rate (FSCR), and the abortion rate (ABR). The impact of MUN levels on the incidence of abortion and non-pregnancy in dairy cows was investigated using logistic regression models. Also, to evaluate the effect of MUN concentrations on reproduction traits, a generalized linear model was used. The MUN2 group had the greatest odds of non-pregnancy (P < 0.05; OR = 2.81; MUN2 vs. MUN1). Also, the MUN4 group had the greatest odds of abortion (P < 0.01, OR = 3.36; MUN4 vs. MUN1). The MUN2 and MUN4 groups had the greatest (51.91%) and the lowest (34.32%) FSCR, respectively. MUN classes had a significant influence on DO (P < 0.05), and MUN4 had the largest value (145.44 days). The results indicated the negative association between MUN with reproduction and fertility in Iranian Holsteins.

Genomic regions associated with embryonic loss in primiparous Holstein cows

IntroductionReproductive efficiency in dairy cattle bred by artificial insemination (AI) or via embryo transfer (ET) is important as a means of facilitating the rate of genetic improvement by utilizing superior genetics from sires and donor dams. Fertility is especially challenging in primiparous cows as they have recently calved, are still growing, and are lactating. Fertility, measured by the conception rate from the first service (CCR1), is the number of cows that become pregnant as a result of the first AI or ET compared to all cows serviced, whereas times bred (TBRD) is the number of inseminations cows bred by AI needed to achieve a successful pregnancy.MethodsThis study aimed to identify the loci associated with and gene sets enriched for the CCR1 in primiparous cows that were bred by AI (n = 882) or were ET recipients (n = 353), and to identify the loci associated with the TBRD (n= 1,851) in primiparous cows. A genome-wide association analysis and gene set enrichment analysis were performed using single-nucleotide polymorphism (SNP) data for the CCR1 and TBRD in primiparous cows. In cows bred by AI, two loci containing five positional candidate genes were associated with the CCR1 (p &amp;lt; 1 × 10−5) and one gene set with 18 leading-edge genes was enriched (NES ≥3) for the CCR1.Results and discussionIn cows that were ET recipients, five loci were associated with the CCR1, but no gene sets were enriched for the CCR1. For the second phenotype, five loci with nine positional candidate genes were associated with the TBRD and two gene sets with eight leading-edge genes were enriched for the TBRD. Identifying the loci associated with or gene sets enriched for the CCR1 and TBRD provides an opportunity to better understand embryonic loss in AI-bred and ET-recipient cows and to use this information to select for higher reproductive efficiency.

A comprehensive analysis of the effects of DGAT1 K232A polymorphism on milk production and fertility traits in Holstein Friesian and Jersey cows reared in Türkiye

Abstract. Research on the diacylglycerol acyltransferase 1 (DGAT1) K232A marker in cattle shows inconsistent results across regions, largely due to small sample sizes, limited genetic variation, and data restricted to few lactations, which complicates establishing a reliable genotype–phenotype correlation. This research aimed to determine the effect of the K232A polymorphism of the bovine DGAT1 gene on milk production and quality traits in dairy cattle. We used 1104 cattle, including 828 Holstein Friesian and 276 Jersey cows. The analysis utilized extensive data from six lactations of cows raised on four commercial dairy farms. We genotyped the population using the polymerase chain reaction–restriction fragment length polymorphism (PCR-RFLP) technique and Sanger sequencing for verification. We then evaluated the 305 d and test-day milk yields as well as fat and protein yields and percentages. The number of inseminations per conception and calving ease were also assessed as reproduction indices. Genotype–phenotype associations were quantified using linear mixed models. The AA genotype was absent in Jersey cows, and the heterozygous genotype was predominant in both breeds. The K232A marker was significantly associated with test-day milk yield, fat, and protein content in Jersey cows. Further, it substantially affected the fat percentage of milk in Holstein Friesian cows (p&lt;0.001). We found that the KK genotype is highly desirable for milk quality and especially fat content. This comprehensive assessment demonstrated that the KK genotype of the DGAT1 K232A polymorphism significantly influenced fat and protein contents in dairy cattle.

Genomic prediction and validation strategies for reproductive traits in Holstein cattle across different Chinese regions and climatic conditions

Accurate genomic predictions of breeding values for traits included in the selection indexes are paramount for optimizing genetic progress in populations under selection. The size of the reference populations is a major factor influencing the accuracy of genomic predictions, which is even more important for lowly-heritable traits such as fertility and reproduction indicators. Combining data from different geographical regions or countries can be beneficial for genomic prediction of these lowly heritable traits. Therefore, the objectives of this study were to: 1) evaluate the benefits of performing across-regional genomic evaluations for reproduction traits in Chinese Holstein cattle; and, 2) assess the feasibility of validating genomic predictions across environments based on reaction norm models (RNM) and the Linear Regression (LR) method after accounting for genotype-by-environment interactions. Phenotypic records from 194,574 cows collected across 47 farms located in 2 regions of China were used for this study. The reference and validation populations were defined based on birth year for applying the LR validation method. The traits evaluated included: interval from first to last insemination (IFL), conception rate at the first insemination (CR_f), and number of inseminations (NS) recorded in heifers and first-parity cows. The results indicated that combining data from different regions resulted in greater genomic prediction accuracies compared with using data from single regions, with increases ranging from 2.74% to 93.81%. This improvement was particularly notable for the region with the least amount of available data, where the increases ranged from 26.49% to 93.81%. Furthermore, the predictive abilities could be validated for all studied traits based on the LR method across different environments when fitting RNM. The prediction accuracies and bias of genomic breeding values based on RNM were better than regular single-trait animal models in extreme climatic conditions for IFL and NS, whereas limited increases in predictive abilities were observed for CR_f. Across-regional genomic prediction by RNM can account for genotype-by-environment interactions, potentially increase the accuracy of genomic prediction, and predict the performances of individuals in the environments with limited phenotypic data available.

Strong associations between the FGF-2 gene and productivity traits of Holstein-Friesian dairy cattle

Sustainability in dairy cattle farms depends on the efficiency of milk yield and reproductive traits. Thus, this study aimed to investigate the effect of the FGF-2/Csp6I gene and major environmental factors on these traits in Holstein-Friesian cattle. A total of 212 whole blood samples were collected from the Vena coccygea of cattle and the data obtained from these samples were used in all statistical analyses. Then, the restriction fragment length polymorphism (RFLP) method (determination of genotypes) was conducted and programs including PopGene (allele and genotype frequencies), Minitab (association analyses) and MTDFREML (variance components and genetic parameters) were used. Alleles A (0.4269) and G (0.5731) as well as genotypes AA (0.174), AG (0.505) and GG (0.321) were found, indicating that the population is polymorphic and in Hardy-Weinberg equilibrium (P > 0.05). The effect of the Csp6I polymorphism of FGF-2 gene on peak milk yield (PMY) (P < 0.01); lactation milk yield (LMY), milking time (MT), 305-day and 200-day lactation milk yield (LMY305 and LMY200), average daily milk yield (ADMY) (P < 0.05); 100-day lactation milk yield (LMY100), age of using in first breeding (AUFB) and number of inseminations per conception (NIPC) (P < 0.10) were significant. The heritability of milk yield traits and the correlation between direct and maternal heritability for reproductive traits were high. Furthermore, the breeding value of PMY was higher for the AA genotype (0.745 ± 0.292) than for the AG genotype (−0.268 ± 0.171) (P < 0.05). As a result, the A allele and AA genotype for the FGF-2/Csp6I gene had an increasing effect on milk yield without compromising reproductive performance in Holstein-Friesian dairy cattle.

A Study of the Impact of Surgical Correction of Left Abomasal Displacement on Fertility Parameters in Lactating Holstein Cows

The left displacement of the abomasum (LDA) is a common condition in dairy cows that can significantly impact their welfare, productivity, and fertility. This study was carried out in Greek dairy farms over a period of 3 years. To ensure early detection, the farmers were trained to accurately identify the disease. The reproductive performance and milk production of 306 cows was assessed by considering the time to the first estrus, the calving-to-conception interval, and the number of artificial inseminations required for the establishment of pregnancy. Uterine health status, the timing of disease diagnosis, and the season of the year were also evaluated. In a separate study, the outcomes of 26 cases where cows suffered LDA and underwent surgical treatment with a delay of at least one week from disease onset, were compared to those of cases promptly treated. The results indicate that even early identification and treatment of LDA affects fertility and milk yield; these impacts worsen with the co-existence of uterine infections of affected. However, in late-treated cases, all reproductive and production indices show significant deterioration. Our findings suggest that timely diagnosis of the disease, preferably by the farmer, ensures minimal losses in cows affected by LDA.

Factors influencing pregnancy loss between days 30 and 70 in a single cattle herd: A comprehensive analysis of sire, cow, and other contributing factors

This retrospective study utilized a mixed-effects logistic model analysis to investigate variables associated with the probability of pregnancy loss (PL) between days 30 and 70 in a dataset comprising 9507 pregnancies from a single cattle herd over 10 years. The model incorporated fixed-effect variables including cow breed (Holstein, Crossbred, and Brown Swiss), parity (1st, 2nd, 3rd, and 4th or more), insemination seasons, insemination number (≤3 vs >3), estrus nature (spontaneous vs synchronized), postpartum problems, sire breed (Holstein, Fleckvieh, Brown Swiss, and Montbéliarde), zygote genotypic (pure vs crossbred), days in milk (DIM) at insemination, actual 305-day milk yield, and sire conception rate. Additionally, random effects included sire (n = 129), cow (n = 3463), and production years (n = 10). The results revealed that cows inseminated with Brown Swiss sires or sires with lower initial conception rates had higher PL rates. Biparous cows, cows with lower 305-day milk yield, cows inseminated later in DIM, cows receiving the 4th or subsequent insemination, and cows inseminated during winter or autumn had lower PL rates. The estrus type and zygote genotype did not significantly impact PL. The random effects of cow, sire, and production years were estimated at 0.230, 0.054, and 0.112, respectively. In conclusion, the study findings suggested that improving management practices for high-yielding cows, cows in early lactation stages, and cows exposed to thermal stress conditions, along with utilizing Brown Swiss cows and sires with high initial conception rates per insemination, could potentially decrease overall PL rates on the farm. Nonetheless, the results did not support the use of Crossbred cows, sires from different breeds, or specific sires to mitigate PL rates on the farm.

DETERMINATION OF FERTILITY OF FIRST CALVING COWS UNDER DIFFERENT HOUSING

The best fertilization rate of firstborns was established at the farm “Kutuzivka” under free housing, it was 11% times higher than at the farm “Agroprogres”, and 7% higher than the farm “Dekabrystiv”. The influence of the "farm" factor – 1.0% was probable (p &lt; 0.001). In our opinion, the higher percentage of fertile inseminations of firstborns is explained by the use of an automatic system for determining sexual desire at the farm "Kutuzivka".The season of the year was the most influential factor in the fertilization of the first-born cows among the factors of the external environment. The largest number of inseminations of first-borns at farm “Agroprogres” was in the summer (28%), and the lowest in the winter (23%). On the farm of the farm “Dekabrystiv”, a greater number of inseminations were also carried out in the summer (30%) months, and the smallest share of inseminations – in the winter (21%). The nature of this impact is explained not by the state of the environment, but by the housing technology and feeding animals. During the first insemination after calving, a slightly lower percentage of fertilization of first-borns was observed in all studied farms. During the second insemination, it increased by 4% in the animals of the farm “Agroprogres”, by 7% in the farm “Decembrists”, by 3% in the farm "Kutuzivka". In the subsequent growth of the number of insemination of firstborns in the first two farms did not lead to probable changes in fertility. At the same time, the animals of the the farm "Kutuzivka", starting from the 5th insemination, were fertilized by 11–23% less than from the second insemination. The influence of this factor on the effectiveness of insemination of cows was improbable in the farm “Agroprogres” and amounted to 0.7%, in the farm “Dekabristov” and the farm "Kutuzivka" 0.8%. It was established that in all experimental farms, the number of artificial insemination after the first calving of cows is not the main factor that determines its fertility. The main factor related to the efficiency of insemination is the stage of lactation. Correlation coefficients of the lactation day with the number of artificial insemination in experimental farms ranged from +0.545 to +0.723 and with the daily productivity of first-borns equaled from +0.156 to +0.383. Low fertility in the first 90 days of lactation is primarily due to a high milk dominance, possibly a negative energy balance during this period of lactation.

Intrauterine administration of paternal and maternal peripheral blood mononuclear cells mix as solution for repeated implantation failure.

To date, implantation is the rate-limiting step for the success of in vitro fertilization (IVF) treatment. Accumulating evidence suggests that immune cells contribute to embryo implantation, and several therapeutic approaches have been proposed for the treatment of recurrent implantation failure (RIF). Endometrial immune modulation with autologous activated peripheral blood mononuclear cells (PBMCs) is one of the most widely used protocols. However, the effect of intrauterine insemination of mixed paternal and maternal-activated PBMCs has not yet been attempted and studied. The aim of our study is to test the effect of the addition of paternal lymphocytes on the implantation rate in RIF patients. Mononuclear cells were isolated from the peripheral blood of 98 RIF patients and cultured for 72h before insemination into the endometrial cavity 48h before embryo transfer. Our patients were divided into 4 groups according to the type and number of PBMCs inseminations. Our study shows that activated PBMCs promoted clinical pregnancy rates (CPR) in all groups. Moreover, we found that the groups injected with more than 2 million cells showed a better clinical outcome and, more interestingly, patients inseminated with both paternal and maternal activated PBMCs showed the highest CPR, reaching 47.2%, in addition to the highest implantation rate 31. 2% and the live birth rate 41.39%. Our work demonstrates the importance of administering a large number of activated PBMCs with the addition of paternal activated PBMCs to immunomodulate the endometrium for the success of in vitro fertilization in RIF patients.

Sexual conflict and sexual networks in bed bugs: the fitness cost of traumatic insemination, female avoidance and male mate choice.

Sexual conflict is prevalent among animals and is primarily caused by the fact that the optimal mating rates are often higher in males than in females. While there is a growing appreciation that females can also gain from multiple matings, we still know relatively little about which sex controls the observed mating rates and how close it is to the optimal female mating rates. To address this issue, we tracked female bed bugs (Cimex lectularius) inseminated daily versus weekly and found that weekly inseminated females lived longer and produced over 50% more offspring. In a follow-up experiment employing a social network framework, we placed 24 bed bugs into a semi-naturalistic arena and recorded all sexual interactions. While recently inseminated females did not avoid males more often, they were more frequently rejected by males. Finally, we tracked avoidance behaviour in a single cohort of female bed bugs as they received six successive daily inseminations. Avoidance rates increased and insemination durations decreased with increasing number of prior inseminations. Overall, our results indicate high costs of polyandry. Although females possess some plastic avoidance strategies, the observed rates of insemination fall closer to the male rather than female optimum.

Customized voluntary waiting period before first insemination in primiparous dairy cows: Effect on milk production, fertility, and health

A customized voluntary waiting period (VWP) before first insemination was tested in 18 commercial dairy herds in Sweden to assess milk production, fertility, and health in primiparous cows expected to be suited for extended VWP. Cow selection for extended VWP was based on 3 criteria in early lactation: (1) the 10% of cows with highest genomic persistency index, (2) cows with a difficult calving or disease during the first month of lactation, and (3) cows with higher yield during d 4 to 33 after calving than the herd average for primiparous cows. Cows meeting at least one of these criteria were randomly assigned to either treatment with an extended VWP of at least 175 d (ExtExt; n = 174, calving interval [CInt] = 16.3 mo) or treatment with a conventional VWP of a maximum of 100 d; (ExtConv; n = 173, CInt = 12.4 mo). Cows not meeting any of the criteria were assigned to the conventional VWP treatment (ConvConv; n = 183, CInt = 12.0 mo). We found no differences in milk yield per day in the CInt between treatments, although 305-d and whole-lactation (WL) milk yields were higher for ExtExt cows (10,371 and 13,803 kg) than ExtConv cows (9,812 and 10,257 kg). Milk yield at the last test milking before dry-off was lower in ExtExt compared with ExtConv cows (24.9 vs. 28.3 kg), but the results showed no difference in dry period length between the treatments. Regarding reproductive performance, the ExtExt cows had a higher first service conception rate (FSCR; 60% vs. 45%) and lower number of inseminations per conception (NINS; 1.67 vs. 2.19), compared with the ExtConv cows. As expected, ConvConv cows had the lowest milk yield (305-d, WL, and per day) in the CInt; however, FSCR and NINS did not differ between ConvConv cows and cows in the other 2 VWP treatments. Disease incidence was higher for cows in the ExtConv compared with the ConvConv treatment, but there was no difference between ExtExt and the 2 other VWP treatments. Further, no difference in the proportion of cows with good udder health or culling rate was detected between any of the treatments, though due to low prevalence, the study lacked power to draw major conclusions on these results. Thus, prolonging VWP for suitable primiparous cows can produce benefits such as improved fertility in the form of higher FSCR and lower NINS, as well as lower dry-off yield, without compromising milk yield or prolonging dry period length.

Impact of reproductive traits on productive life in Iranian Holstein dairy cows.

Enhancing reproductive performance is a key strategy to mitigate involuntary culling rates, thereby extending productive life (PL) and ultimately improving profitability in dairy cattle herds. A piecewise Weibull proportional hazards model was used to investigate the effect of several important reproductive traits on PL in Holstein dairy cows. Data comprised 200,747 lactation records from 82,505 cows sired by 1952 bulls across 36 dairy herds. PL was defined as the number of days from the first calving to the last milk record or censoring. The statistical model accounted for the time-dependent fixed effects of changes in herd size, year-season, milk production, fat and protein contents, and the time-independent fixed effect of age at first calving. Herd-year and sire effects were also included as random effects. Reproductive traits include calving traits such as calving ease (CE), calf size (CZ), and calf survival (CS), as well as female fertility traits such as number of inseminations per conception (NI), days from calving to first service (CFS), days from first service to conception (FSC), and days open (DO). All reproductive traits had a significant effect on PL (p < 0.001). Each reproductive trait was analysed separately. The relative risk (RR) of being culled increased as the severity of calving difficulties increased in both primiparous and multiparous cows. Cows that calved small or large calves showed a higher risk of being culled compared with those that calved medium size calves. The increased RR of culling was observed only for primiparous cows that gave birth to dead calves. In addition, cows that required more NI, a longer CFS, FSC, and DO had shorter longevity. These insights can deepen our comprehension of the factors affecting PL and provide information for refining management and breeding strategies, which could lead to increased profitability and sustainability in Iranian dairy farming.

Estimation of genetic correlations and genomic prediction accuracy for reproductive and carcass traits in Hanwoo cows.

This study estimated the heritabilities (h2) and genetic and phenotypic correlations between reproductive traits, including calving interval (CI), age at first calving (AFC), gestation length (GL), number of artificial inseminations per conception (NAIPC), and carcass traits, including carcass weight (CWT), eye muscle area (EMA), backfat thickness (BF), and marbling score (MS) in Korean Hanwoo cows. In addition, the accuracy of genomic predictions of breeding values was evaluated by applying the genomic best linear unbiased prediction (GBLUP) and the weighted GBLUP (WGBLUP) method. The phenotypic data for reproductive and carcass traits were collected from 1,544 Hanwoo cows, and all animals were genotyped using Illumina Bovine 50K single nucleotide polymorphism (SNP) chip. The genetic parameters were estimated using a multi-trait animal model using the MTG2 program. The estimated h2 for CI, AFC, GL, NAIPC, CWT, EMA, BF, and MS were 0.10, 0.13, 0.17, 0.11, 0.37, 0.35, 0.27, and 0.45, respectively, according to the GBLUP model. The GBLUP accuracy estimates ranged from 0.51 to 0.74, while the WGBLUP accuracy estimates for the traits under study ranged from 0.51 to 0.79. Strong and favorable genetic correlations were observed between GL and NAIPC (0.61), CWT and EMA (0.60), NAIPC and CWT (0.49), AFC and CWT (0.48), CI and GL (0.36), BF and MS (0.35), NAIPC and EMA (0.35), CI and BF (0.30), EMA and MS (0.28), CI and AFC (0.26), AFC and EMA (0.24), and AFC and BF (0.21). The present study identified low to moderate positive genetic correlations between reproductive and CWT traits, suggesting that a heavier body weight may lead to a longer CI, AFC, GL, and NAIPC. The moderately positive genetic correlation between CWT and AFC, and NAIPC, with a phenotypic correlation of nearly zero, suggesting that the genotype-environment interactions are more likely to be responsible for the phenotypic manifestation of these traits. As a result, the inclusion of these traits by breeders as selection criteria may present a good opportunity for developing a selection index to increase the response to the selection and identification of candidate animals, which can result in significantly increased profitability of production systems.

Evaluation of the Relationship of Some Environmental Factors and Number of Inseminations per Pregnancy with Milk Yield in Holstein Cows

In order to investigate the relationship between some environmental factors and the number of artificial inseminations per pregnancy with milk yield, data of 90 healthy Holstein breed dairy cows in a private dairy farm in Karapınar district of Konya province were taken. For the utilization of the data, age, number of artificial inseminations, lactation yield, calving season and sequence of lactation records were taken from the herd management program in the enterprise and analysed. As a result of the analysis, the number of artificial inseminations per pregnancy in 2016 was 1.79 and lactation milk yield was 10079,41 kg; the number of artificial inseminations per pregnancy in 2017 was 2.16 and lactation milk yield was 9767.94 kg. There was a statistically significant relationship between the number of artificial inseminations per pregnancy and milk yield during lactation period in both years. As a result, the increase in the number of artificial inseminations per pregnancy negatively affected the average milk yield of lactation period. Genetic and environmental factors are thought to play a major role in this effect.

Genome-wide associative analysis of reproductive characteristics of a black-and-white Holstein cattle population in the conditions of the Northwestern region

In recent years, genomic assessment and the widespread introduction of modern biotechnological techniques have played a leading role in the implementation of breeding programs. For a long time, increasing milk productivity has been the main goal of breeding. This led to a significant decrease in reproduction in herds. The reproductive indicators of the uterine livestock of cattle can largely reduce the total profitability due to additional costs for manual, veterinary assistance and forced culling. Experienced groups are genotyped using the Bovinesnp50 V3 Beadchip chip are formed from the cows of black-and-white holsteinized breed. For the study, the main reproductive traits of cows were chosen: the age of the first insemination, the insemination indices in front of the first (a), the second (b), the third (c), fourth (d) lactation and the period between hotels. Analysis of associations throughout the genome was carried out using EMMAX software. 2 significant SNP and 5 conditionally significant were found. The CAMK2D candidate gene with the age at the first insemination, the TLN2, WSCD2, GAPT genes with the indicator, the number of insemination and genes WDR36, TDRD10 with the inter -suffering period was identified. Based on the studies, we assume that with age there is a change in the genetic factors affecting animal fertility. The identified candidate genes affect the mechanisms of maturation of follicles, so the growth and development of embryos. The results can be used both for the selection of animals to improve reproduction indicators, and for the search for the fundamental foundations of the formation of fertility in cattle.

Genome-wide association study identifies genomic regions associated with key reproductive traits in Korean Hanwoo cows.

Conducting genome-wide association studies (GWAS) for reproductive traits in Hanwoo cattle, including age at first calving (AFC), calving interval (CI), gestation length (GL), and number of artificial inseminations per conception (NAIPC), is of paramount significance. These analyses provided a thorough exploration of the genetic basis of these traits, facilitating the identification of key markers for targeted trait improvement. Breeders can optimize their selection strategies, leading to more efficient and sustainable breeding programs, by incorporating genetic insights. This impact extends beyond individual traits and contributes to the overall productivity and profitability of the Hanwoo beef cattle industry. Ultimately, GWAS is essential in ensuring the long-term genetic resilience and adaptability of Hanwoo cattle populations. The primary goal of this study was to identify significant single nucleotide polymorphisms (SNPs) or quantitative trait loci (QTLs) associated with the studied reproductive traits and subsequently map the underlying genes that hold promise for trait improvement. A genome-wide association study of reproductive traits identified 68 significant single nucleotide polymorphisms (SNPs) distributed across 29 Bos taurus autosomes (BTA). Among them, BTA14 exhibited the highest number of identified SNPs (25), whereas BTA6, BTA7, BTA8, BTA10, BTA13, BTA17, and BTA20 exhibited 8, 5, 5, 3, 8, 2, and 12 significant SNPs, respectively. Annotation of candidate genes within a 500kb region surrounding the significant SNPs led to the identification of ten candidate genes relevant to age at first calving. These genes were: FANCG, UNC13B, TESK1, TLN1, and CREB3 on BTA8; FAM110B, UBXN2B, SDCBP, and TOX on BTA14; and MAP3K1 on BTA20. Additionally, APBA3, TCF12, and ZFR2, located on BTA7 and BTA10, were associated with the calving interval; PAX1, SGCD, and HAND1, located on BTA7 and BTA13, were linked to gestation length; and RBM47, UBE2K, and GPX8, located on BTA6 and BTA20, were linked to the number of artificial inseminations per conception in Hanwoo cows. The findings of this study enhance our knowledge of the genetic factors that influence reproductive traits in Hanwoo cattle populations and provide a foundation for future breeding strategies focused on improving desirable traits in beef cattle. This research offers new evidence and insights into the genetic variants and genome regions associated with reproductive traits and contributes valuable information to guide future efforts in cattle breeding.