Conception Rate Of 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.

Effect of Removal of Follicular Cyst Content on Success of Ovsynch in Dairy Cows

The purpose of this study was to evaluate the effect of removing cyst content on conception rate in dairy cows treated for follicular cysts with Ovsynch. The trial was conducted using data collected over regular herd health visits in a private practice.

Heat Detection, Conception and Pregnancy Rates of Holstein Cows in Central Chile

Although the HDR of this particular Chilean cattle population may be considered good, there is still room for progress in order to improve fertility of Chilean dairy herds.

Effect of progesterone, human chorionic gonadotropin and progesterone + human chorionic gonadotropin treatment on conception rates in repeat breeder cows

The aim of this study was to investigate the effects of hormonal support on the pregnancy rate in repeat breeder cows. Prostaglandin F2α + Ovsynch oestrus synchronization protocol was applied to the cows. Following the fixed time insemination (day 0), the cows were divided into 4 groups. In Group 1 (n = 42), progesterone releasing intravaginal device (PRID) was placed vaginally at 84 h and removed on the 9th day after the artificial insemination. In Group 2 (n = 40), the cows were administered human chorionic gonadotropin (hCG) on the 7th day. Group 3 (n = 45) was applied a combination of progesterone and hCG. Group 4 (n = 42) was not given any treatment. Blood samples were collected from all cows 4 times on days 3.5, 7, 12, and 18 to evaluate progesterone concentrations. The pregnancy rates were 40.47%, 37.50%, 44.44%, and 30.95% in Group 1, 2, 3, and 4, respectively (P > 0.05). In addition, in cows with progesterone concentrations <2 ng/ml on day 3.5, the pregnancy rates were found to be lower than in the cows with progesterone concentrations >2 ng/ml in Group 4 (P < 0.05). Progesterone supplementation in cows with progesterone concentrations < 2 ng/ml appeared to increase pregnancy rates (P < 0.05) in Groups 1 and 3. As a result, post-insemination hormonal applications in the repeat breeder cows did not increase the pregnancy rate. However, it was concluded that determination of progesterone concentrations on day 3.5 following artificial insemination and then hormonal support in the cows with low concentrations would increased the pregnancy rate.

An investigation of the time period within which frozen-thawed semen delivers a high conception rate in lactating dairy cows.

We determined the length of time within which frozen-thawed semen delivered a high conception rate in present-day lactating dairy cows. The cows utilized were a total 100 milking Holstein-Friesian cows kept in tie-stall style farms. We carried out artificial insemination (AI) during the periovulatory period at a predicted time based on ovulation, and checked ovulation at 6-h intervals after AI. The period from AI to ovulation ranged from 48 h (i.e., 48 h before ovulation) to -12 h (i.e., 12 h after ovulation). High conception rates averaging 63.0% were obtained by carrying out AI > 6–30 h before ovulation, significantly higher than the conception rates of 30.0% (P < 0.05) and 26.9% (P < 0.01) from AI carried out earlier than 30 h before ovulation and later than 6 h before ovulation, respectively. It was concluded that frozen-thawed semen delivers a conception rate of ≥ 60% for > 24–30 h after AI, and that a conception rate of ≥ 60% can be achieved by carrying out AI 6–30 h before ovulation using frozen-thawed semen.

Effect of seasons on the conception rate of cows and buffaloes inseminated by A.I. in Baghpat of Uttar Pradesh

Effect of seasons on the conception rate of cows and buffaloes inseminated by A.I. in Baghpat of Uttar Pradesh

394 Exploring the relationships between cow-calf management systems as affected by protein/methionine nutrition during gestation on the performance of cow-calf pairs prior to weaning

Abstract A three-way factorial arrangement was used to assess impacts of protein/methionine nutrition during gestation and two lactational management systems on performance of cow-calf pairs pre-weaning. 140 crossbred beef cows were managed in drylot and randomly assigned to one of six nutritional treatments during the third trimester of gestation. Cows were fed to meet 110% (HP), 100% (MP), or 90% (LP) of metabolizable protein requirements for late-gestation (NRC, 2016), with(without) rumen-protected methionine (RPM) for 8 weeks prior to parturition. Post-partum, cow-calf pairs were managed in drylot (DL) and fed ad libitum, a ration formulated to meet lactational nutrient requirements, or rotationally grazed on pasture (PAS). Cow body weights (BW) and body condition scores (BCS) and calf BW were recorded at regular intervals. All data were analyzed using PROC GLIMMIX (SAS v9.4). HP cows were heaviest at calving (P = 0.02), but calf birthweight was unaffected by gestational nutrition (P &amp;gt; 0.19). Gestational nutrition did not impact cow conception rate (CR), or calf BW and ADG (P &amp;gt; 0.17). Lactational management system (PAS, DL) did not affect cow BCS or CR (P &amp;gt; 0.13), but impacted cow and calf BW and ADG. PAS calves were heavier, had greater ADG, and heavier weaning BW than DL calves (P &amp;lt; 0.02). This came at the expense of BW loss throughout lactation and lower ADG for PAS cows, versus BW gains and greater ADG for DL cows (P &amp;lt; 0.0001). An interaction between protein level and RPM supplementation was present for cow BW at calving and weaning, and BW change throughout lactation (P &amp;lt; 0.04), with tendencies for interactions for cow ADG and BCS (P &amp;lt; 0.09). Overall, prepartum protein/methionine supplementation did not affect calf performance prior to weaning, but may have affected cow performance during lactation. Rotationally grazing cow-calf pairs on pasture improved pre-weaning calf gains, but reduced cow gains throughout lactation.

Effect of SpermVital® technology on conception rate in repeat breeder multiparous dairy cows: preliminary results

The aim of this study was to investigate the effect of SV technology on conception rates in repeat breeder multiparous dairy cows. Seventy-nine multiparous Holstein cows from a private dairy farm were used in the study. These animals were cows that had failed to conceive from at least 3 regularly spaced services (repeat breeders). Estrus cycles of the cows were synchronized by 2 injections of the PG analogue, administered 11 days apart. GnRH was applied 48 h after the second injection of PG. Twenty-four h after this administration, the animals were randomly divided into 2 groups, control and SV. The animals in the control group (n = 28) were inseminated with standard processed semen, and the cows in the SV group (n = 51) were inseminated with SV® technology processed semen. A lower pregnancy rate (35.5%) was determined in the control group than in the SV (47.1%) group. The difference between pregnancy rates in the groups was statistically significant (P < 0.05). We are at too early a stage to say that SVArtificial insemination, repeat breeder, SpermVital® technology® Technology can fully respond to the deficiencies in herd management. This work may also lead to future studies into the use of more animal material.

155 Fertility of sexed semen in Holstein heifers and cows

Compared with conventional semen, use of sexed semen decreases the conception rate (CR); therefore, it is important to address the factors that lead to sperm damage. Recently, a novel sexed semen technology was developed for improving dairy cattle fertility (Betthauser et al. 2016 J. Dairy Sci. 99 (E-Suppl. 1), 534). However, there are few reports about the fertility of this novel sexed semen in dairy cattle in Japan. The objective of this study was to compare the CR of traditional sorting semen (S1: flow cytometry/cell sorting) and the novel sexed semen (S2: SexcelTM, ABS Global Inc.) in Holstein heifers and cows in Japan. The CR for the first insemination was obtained from 391 Holstein cows and 148 heifers (10.7-17.8 months old) from 14 dairy farms in Hokkaido from June 2017 to April 2019. Semen used for AI was collected from six bulls and packaged into 0.25-mL straws and frozen. Cows inseminated with conventional frozen semen (S3: unsexed semen in 0.5-mL straws) were used as controls. Calving data were collected from 123 cows and 69 heifers that had calved between January 2018 and May 2019. The diagnosis of pregnancy was confirmed using ultrasonography between 30 and 45 days after insemination. The CR and sex ratio were analysed using chi-square test. The average parity number was 1.9±1.1, and average days open was 84.9±20.4 days. The average interval between calving and the first service was 86.2±20.3 days. The average milk yield (at 305 days) was 12 195±1595 kg. All of the animals were inseminated after the onset of standing heat or removal of the tail chalk of natural heats and oestrus and ovulation synchronisation programmes on the farm. Conception rates of heifers of the first service of S1 (n=54) and S2 (n=94) were 68.5 and 70.2%, respectively. Conception rates of cows of the first service of S1 (n=32), S2 (n=173), and S3 (n=186) were 56.3, 57.8, and 53.8%, respectively. There were no significant differences in CR between these groups (P&amp;gt;0.4). The proportion of female calves produced using S1 (n=61) and S2 (n=57) was 91.8 and 93.0%, respectively, which was significantly more (P&amp;lt;0.01) compared with the 50.0% produced using S3 (n=74). There were no significant differences between S1 and S2 (P&amp;gt;0.8) in terms of the proportion of calves produced. The results of this study demonstrated that the traditional sorting and novel sexed semen (S1 and S2, respectively) did not differ in terms of the first-service CR and produced considerably more female calves than when the conventional semen (S3) was used. Furthermore, these findings indicate that the use of this novel sexed semen could achieve a sex ratio close to 90% female offspring.

Short communication: A splice site mutation in CENPU is associated with recessive embryonic lethality in Holstein cattle

A genome scan for homozygous haplotype deficiency coupled with whole-genome sequence data analysis is a very effective method to identify embryonic lethal mutations in cattle. Among other factors, the power of the approach depends on the availability of a greater amount of genotyping and sequencing data. In the present study, we analyzed the largest known panel of Illumina BovineSNP50 (Illumina Inc., San Diego, CA) genotypes, comprising 401,896 Holstein animals, and we report the mapping of a new embryonic lethal haplotype on chromosome 27, called HH7. We fine mapped the locus in a 2.0-Mb interval using an identical-by-descent approach and analyzed genome sequence data from 4 carrier and 143 noncarrier Holstein bulls to identify the causative mutation. We detected a strong candidate variant in the gene encoding centromere protein U (CENPU), a centromere component essential for proper chromosome segregation during mitosis. The mutant allele is a deletion of 4 nucleotides located at position +3 to +6 bp after the splicing donor site of exon 11. Cross-species nucleotide alignment revealed that the nucleotide at position +3 is entirely conserved among vertebrates, suggesting that it plays an important role in the regulation of CENPU splicing. For verification, we genotyped the candidate variant in 232,775 Holstein individuals and did not observe any homozygotes, whereas 16 were expected (Poisson P-value = 1.1 × 10-7; allele frequency = 0.8%). In addition, genotyping of 250,602 animals from 19 additional breeds revealed that the mutant allele is restricted to animals of Holstein descent. Finally, we estimated the effect of the candidate variant on 2 fertility traits in at-risk mating (i.e., between carrier bulls and daughters of carrier bulls) versus non-risk mating. In agreement with a recessive lethal inheritance pattern, we observed a marked reduction in both conception rate and 56-d nonreturn rate in heifers and cows. The effect on 56-d nonreturn rate suggests that a substantial proportion of homozygous mutants die before 35 d after insemination, which is consistent with the early embryonic death previously reported in CENPU-/- mouse embryos. In conclusion, we demonstrate that with more than 400,000 genotypes, we can map very rare recessive lethal mutations segregating at a frequency below 1% in the population. We recommend performing new analyses regularly as data are accumulating.

Identification of loci associated with conception rate in primiparous Holstein cows

BackgroundSubfertility is a major issue facing the dairy industry as the average US Holstein cow conception rate (CCR) is approximately 35%. The genetics underlying the physiological processes responsible for CCR, the proportion of cows able to conceive and maintain a pregnancy at each breeding, are not well characterized. The objectives of this study were to identify loci, positional candidate genes, and transcription factor binding sites (TFBS) associated with CCR and determine if there was a genetic correlation between CCR and milk production in primiparous Holstein cows. Cows were bred via artificial insemination (AI) at either observed estrus or timed AI and pregnancy status was determined at day 35 post-insemination. Additive, dominant, and recessive efficient mixed model association expedited (EMMAX) models were used in two genome-wide association analyses (GWAA). One GWAA focused on CCR at first service (CCR1) comparing cows that conceived and maintained pregnancy to day 35 after the first AI (n = 494) to those that were open after the first AI (n = 538). The second GWAA investigated loci associated with the number of times bred (TBRD) required for conception in cows that either conceived after the first AI (n = 494) or repeated services (n = 472).ResultsThe CCR1 GWAA identified 123, 198, and 76 loci associated (P < 5 × 10− 08) in additive, dominant, and recessive models, respectively. The TBRD GWAA identified 66, 95, and 33 loci associated (P < 5 × 10− 08) in additive, dominant, and recessive models, respectively. Four of the top five loci were shared in CCR1 and TBRD for each GWAA model. Many of the associated loci harbored positional candidate genes and TFBS with putative functional relevance to fertility. Thirty-six of the loci were validated in previous GWAA studies across multiple breeds. None of the CCR1 or TBRD associated loci were associated with milk production, nor was their significance with phenotypic and genetic correlations to 305-day milk production.ConclusionsThe identification and validation of loci, positional candidate genes, and TFBS associated with CCR1 and TBRD can be utilized to improve, and further characterize the processes involved in cattle fertility.

Body Condition Score and Milk Production on Conception Rate of Cows under a Small-Scale Dairy System

Simple SummarySmall-scale dairy farms are important because they generate jobs in rural areas and improve food security, income, and livelihood worldwide. On the other hand, high fertility is strongly associated with the profitability of dairy farms. Therefore, improving reproductive performance would increase milk production and farmers’ incomes. In the present study, we focus on the effect of body condition score (BCS) of Holstein cows at calving and when they are bred for the first time (after calving) on a key reproductive performance indicator: conception rate to first service. Additionally, we studied the association between BCS at calving and milk production, assuming that cows had a moderate genetic potential for milk production. Our results highlight the importance of BCS on the future reproductive performance and productivity of cows in a small-scale dairy system. These results are useful to implement management strategies in order to increase conception rate to first service and milk production in this type of dairy farm.Management and production characteristics impact conception rate to first service (CR1S) in small-scale dairy farms, but the impact of body condition score (BCS) and milk production levels on cows’ fertility is unknown. Our objective is to determine the effect of BCS and milk production on CR1S in small-scale dairy farms of western Mexico. Logistic regression models are used to determine the effect of BCS (at calving and first service), 60-d and 305-d milk production, protein and fat production, lactation number, and days at first service on CR1S. BCS at calving does not affect CR1S in cows with three or more lactations (39.5%; p > 0.1). However, first-lactation cows with BCS < 3.0 at calving and second lactation cows with BCS ≤ 2.5 at calving have higher CR1S (63.2 and 67.9%, respectively; p < 0.1). This result is perhaps due to reduced milk production, which leads to lower metabolic stress. BCS ≤ 2.5 at calving is associated (p < 0.05) with a reduced milk yield, explaining partially the observed higher CR1S in these groups. Cows with BCS ≤ 2.5 at first service in the higher quartile of 60-d milk production (≥ 28kg/day) show lower CR1S (23.9 and 51.1%, respectively; p < 0.01). In conclusion, BCS at calving and at first service, 60-d milk production, and lactation number are factors associated with CR1S.

Association of lipid-related genes implicated in conceptus elongation with female fertility traits in dairy cattle

Elongation of the preimplantation conceptus is a requirement for pregnancy success in ruminants, and failures in this process are highly associated with subfertility in dairy cattle. Identifying genetic markers that are related to early conceptus development and survival and utilizing these markers in selective breeding can improve the reproductive efficiency of dairy herds. Here, we evaluated the association of 1,679 SNP markers within or close to 183 candidate genes involved in lipid metabolism of the elongating conceptus with different fertility traits in US Holstein cattle. A total of 27,371 bulls with predicted transmitting ability records for daughter pregnancy rate, cow conception rate, and heifer conception rate were used as the discovery population. The associations found in the discovery population were validated using 2 female populations (1,122 heifers and 2,138 lactating cows) each with 4 fertility traits, including success to first insemination, number of services per conception, age at first conception for heifers, or days open for cows. Marker effects were estimated using a linear mixed model with SNP genotype as a linear covariate and a random polygenic effect. After multiple testing correction, 39 SNP flagging 27 candidate genes were associated with at least one fertility trait in the discovery population. Of these 39 markers, 3 SNP were validated in the heifer population and 4 SNP were validated in the cow population. The 3 SNP validated in heifers are located within or near genes CAT, MYOF, and RBP4, and the 4 SNP validated in lactating cows are located within or close to genes CHKA, GNAI1, and HMOX2. These validated genes seem to be relevant for reducing pregnancy losses, and the SNP within these genes are excellent candidates for inclusion in genomic tests to improve reproductive performance in dairy cattle.

Quantitative relationship between climatic conditions and the conception rate of Japanese Black cattle in commercial cow–calf operations

Heat stress has a major effect on mammalian reproductive function. To clarify the relationship between heat stress and reproduction, it is important to investigate the quantitative relationship between the conception rate (CR) of beef cattle and climatic conditions. Therefore, the present study aimed to investigate the quantitative relationship between the CR of beef cattle and climatic conditions, as measured by the maximum temperature (MAX) and the temperature-humidity index (THI), in commercial cow–calf operations. Data were collected from 10,599 farms in Miyazaki, Japan, including records for 131,837 services of 79,265 heifers and 821,807 services of 147,464 cows between January 2005 and December 2014. Climate data in the vicinity of the farms were collected from the Japan Meteorological Agency. THI was calculated as 0.8 × meanT + (meanRH/100) × (meanT - 14.4) + 46.4; where T was the temperature, and RH was the relative humidity. The observational unit was an artificial insemination (AI) record, and the dependent variable was conception (1 or 0). Climatic conditions were calculated as the average value during the 21 days prior to the AI date, and each climatic condition was separately entered into the model for analysis. The mean CR in heifers was 57.4%. The CR in heifers was associated with climatic conditions (MAX and THI) and the AI number (P < 0.05), but not with the age at first AI. There were no interactions between factors regarding the CR of heifers. The CR of heifers increased with increasing MAX (odds ratio, 1.002) and THI (odds ratio, 1.001). The mean CR in cows was 54.9%. In a model using the MAX, the CR was associated with the MAX, parity, interval from calving to first AI, and AI number (P < 0.05). Significant interactions were found between the MAX and the interval from calving to first AI, and between the quadratic effect of MAX and the AI number. In a model using the THI, the CR was associated with the THI, parity, interval from calving to first AI, and AI number (P < 0.05). Significant interactions were found between the THI and the interval from calving to first AI, and between the THI and the AI number. In summary, low environmental temperature was associated with low CR in Japanese Black cattle.

Estimation of inbreeding effect on conception in Czech Holstein

The influence of calculated inbreeding coefficients on the conception of heifers and cows was analysed by a two-trait binary model for conceived/not conceived after each insemination on 677 234 Czech Holstein cows and heifers with 3 248 299 insemination records as the covariable in a statistical model. The data between 1996 and 2014 were analysed. Various effects and their statistical influence on traits were tested by a generalized linear model. Consequently, genetic parameters were estimated by the Gibbs sampling method and used in predicting breeding values using the best linear unbiased prediction by animal model (BLUP-AM). The mean for the conception rate of cows averaged over lactations was 33.7% and for heifers it reached 53.8%. Average inbreeding coefficient increased from 1% in 1996 to almost 5% by 2013 and was in the range of 0–45%. The rate of inbreeding per generation was 0.20%. Although the effect of inbreeding was statistically significant (P = 0.05) for both traits, the proportion of variability explained by the models was relatively low. Estimated genetic parameters were low for both traits. Coefficient of heritability was 2.00% and 1.30% for cows and heifers, respectively, whereas coefficients of repeatability reached 6.09% and 7.08% for cows and heifers, respectively. The random effect of the permanent environment (PE) reached higher values than the additive genetic variance (G) and explained 5.67% and 4.09% of variability for cows and heifers, respectively. A negative impact of inbreeding on heifer and cow conception was observed, whereby every 10% increase in inbreeding coefficient resulted in a conception decline by 2.23%. Calculated Spearman’s rank correlation coefficient between estimated breeding values considering and not considering the effect of inbreeding was close to one. Presented results indicate that inbreeding has a negligible influence on the breeding values of conception. The results also indicate that it is not necessary to include inbreeding coefficient in the routine breeding value evaluation of conception rate of heifers and cows. On the other hand, monitoring of inbreeding is necessary to avoid an increase of its rate.

Udder and Claw-Related Health Traits in Selection of Czech Holstein Cows

Abstract The aim of the study was to investigate the impact of the implementation of new health traits into the breeding objective and selection criteria for Czech Holstein cows on the genetic selection response in the breeding objective traits. Incidence of overall claw diseases was included into the current breeding objective for cows (11 traits together). Three traits that indicated claw health (incidence of claw diseases overall and infectious and non-infectious claw diseases) and incidence of clinical mastitis were successively added to the current selection criteria in a cow selection index (a maximum of 19 traits). Selection responses in the breeding objective traits were estimated by applying the general principles of the selection index theory. The required genetic variances for the new traits, the economic weights for all breeding objective traits and the genetic correlations among the selection index traits were estimated within this study. The marginal economic weights, which were calculated for two-year-old cows by applying a bioeconomic model with implemented gene flow, were -193 and -168 € per case for clinical mastitis and overall claw disease incidence, respectively. Using the comprehensive selection index with 19 traits, the reduction in the incidence of both udder and claw diseases was calculated to be 0.004 cases per cow per year. At the same time, a more favourable genetic selection response was obtained for other functional traits, e.g., +0.020% for cow conception rate and +0.010 years for productive life of cow (which represented the profit of 67 € and 367 € per herd and per year, respectively) when compared to the current index. Based on this study, a direct selection of cows for claw and udder health is nowadays recommended to improve the health status of herds and economics in production systems.

Short communication: Phenotypic and genetic effects of the polled haplotype on yield, longevity, and fertility in US Brown Swiss, Holstein, and Jersey cattle

Phenotypes from the December 2018 US national genetic evaluations were used to compute effects of the polled haplotype in US Brown Swiss (BS), Holstein (HO), and Jersey (JE) cattle on milk, fat, and protein yields, somatic cell score, single-trait productive life, daughter pregnancy rate, heifer conception rate, and cow conception rate. Lactation records pre-adjusted for nongenetic factors and direct genomic values were used to estimate phenotypic and genetic effects of the polled haplotype, respectively. No phenotypic or direct genomic values effects were different from zero for any trait in any breed. Genomic PTA (gPTA) for the lifetime net merit (NM$) selection index of bulls born since January 1, 2012, that received a marketing code from the National Association of Animal Breeders (Madison, WI), and cows born on or after January 1, 2015, were compared to determine whether there was a systematic benefit to polled or horned genetics. Horned bulls had the highest average gPTA for NM$ in all 3 breeds, but that difference was significant only in HO and JE (HO: 615.4 ± 1.9, JE: 402.3 ± 3.4). Homozygous polled BS cows had significantly higher average gPTA for NM$ than their heterozygous polled or horned contemporaries (PP = 261.4 ± 43.5, Pp = 166.1 ± 13.7, pp = 174.1 ± 1.8), but the sample size was very small (n = 9). In HO and JE, horned cows had higher gPTA for NM$ (HO = 378.3 ± 0.2, JE = 283.3 ± 0.3). Selection for polled cattle should not have a detrimental effect on yield, fertility, or longevity, but these differences show that, in the short term, selection for polled over horned cattle will result in lower rates of genetic gain.

A Large-Scale Genome-Wide Association Study in U.S. Holstein Cattle.

Genome-wide association study (GWAS) is a powerful approach to identify genomic regions and genetic variants associated with phenotypes. However, only limited mutual confirmation from different studies is available. We conducted a large-scale GWAS using 294,079 first-lactation Holstein cows and identified new additive and dominance effects on five production traits, three fertility traits, and somatic cell score. Four chromosomes had the most significant SNP effects on the five production traits, a Chr14 region containing DGAT1 mostly had positive effects on fat yield and negative effects on milk and protein yields, the 88.07–89.60 Mb region of Chr06 with SLC4A4, GC, NPFFR2, and ADAMTS3 for milk and protein yields, the 30.03–36.67 Mb region of Chr20 with C6 and GHR for milk yield, and the 88.19–88.88 Mb region with ABCC9 as well as the 91.13–94.62 Mb region of Chr05 with PLEKHA5, MGST1, SLC15A5, and EPS8 for fat yield. For fertility traits, the SNP in GC of Chr06, and the SNPs in the 65.02–69.43 Mb region of Chr01 with COX17, ILDR1, and KALRN had the most significant effects for daughter pregnancy rate and cow conception rate, whereas SNPs in AFF1 of Chr06, the 47.54–52.79 Mb region of Chr07, TSPAN4 of Chr29, and NPAS1 of Chr18 had the most significant effects for heifer conception rate. For somatic cell score, GC of Chr06 and PRLR of Chr20 had the most significant effects. A small number of dominance effects were detected for the production traits with far lower statistical significance than the additive effects and for fertility traits with similar statistical significance as the additive effects. Analysis of allelic effects revealed the presence of uni-allelic, asymmetric, and symmetric SNP effects and found the previously reported DGAT1 antagonism was an extreme antagonistic pleiotropy between fat yield and milk and protein yields among all SNPs in this study.

Efficacy of different estrus synchronization protocols on estrus induction response and conception rate in acyclic and cyclic crossbred cows

A study was carriedout under field conditions on 50 acyclic/anestrus and 50 cyclic/ repeat breeder HF crossbred cows to evaluate the efficacy of four standard estrus induction/ ovulation synchronization protocols, viz., Ovsynch (GPG), Ovsynch Plus (PMSG+GPG), Doublesynch (P-GPG) and Estradoublesynch (P-GPE) (10 cows in each protocol, and in untreated controls) in terms of estrus induction response and conception rates at induced estrus with fixed time AI (FTAI) and overall of 3 cycles. All the selected animals received pre-synchronization treatment, viz., Inj. Ivermectin and Tono-vita once i/m and multimineral bolus 1 daily for 7 days. Repeat breeding cows received additional single shot i/m injection of Enrofloxacin. All the anestrus and repeat breeder cows (100 %) under all four treatment protocols exhibited induced estrus within 48-72 hrs from PGF 2 α injection. The conception rates obtained in anestrus cows at induced estrus (FTAI) and overall of three cycles post-treatment were 20.0 and 60.0 % with Ovsynch; 20.0 and 50.0 % with Ovsynch Plus; 40.0 and 80.0 % with Doublesynch, and 30.0 and 60.0 % with Estradoublesynch protocol, respectively. The corresponding conception rates in repeat breeder cows were 30.0 and 70.0 % with Ovsynch; 30.0 and 50.0 % with Ovsynch Plus; 40.0 and 80.0 % with Doublesynch, and 20.0 and 60.0 % with Estradoublesynch protocol, respectively. All non-conceived repeat breeding cows under each protocol, except 1 in Ovsynch Plus protocol, continued cycling, while among 10 anestrus cows each treated with Ovsynch, Ovsynch Plus, Doublesynch and Estradoublesynch protocol, 2, 2, 0 and 1 cows again turned out to be anestrus by 60 days post-induction/FTAI, respectively. Among the untreated control anestrus and repeat breeder cows (10 each), 2 and 3 cows conceived over a period of 90 days follow up giving overall conception rates of only 20.0 and 30.0 %, respectively, as against the overall fertility rate of 62.50 and 65.00 % in treated anestrus and repeat breeder cows, respectively, over just mean 28-32 days of treatment, suggesting the economic utility of these protocols in handling the problem breeder cows under field conditions.

Fucosyltransferase gene expression in goat endometrium during the estrous cycle and early pregnancy

Regulation of the expression of the alpha(1,2)fucosyltransferase (FUT) genes and their enzymatic products, including the H-type 1 antigen (HT1), on the luminal surface of the uterus is believed to be critical for establishment of pregnancy in mammals. The FUT1 gene is a marker for conception rates in dairy cows and HT1 is a marker for uterine receptivity in rodents. To determine the spatiotemporal expression patterns of FUT1 and FUT2 genes in goats, endometrial tissues were obtained on six days spanning the estrous cycle (Days 5, 11, 13, 15, 17 and 19) and seven days spanning early pregnancy (Days 5, 11, 13, 15, 17, 19 and 25). In all data, we found no effect of status (cyclic or pregnant; P > 0.1) and pooled data where appropriate. We cloned FUT1 cDNA from goat endometrium and made probes from it for Northern and slot blot analyses. The analyses indicated that FUT1 gene expression was high until Day 13, and then declined. In situ hybridization revealed a change in the cell-specificity of FUT1 gene expression over the estrous cycle and early pregnancy. In situ hybridization signal intensity scores indicated that FUT1 expression by uterine epithelium was high on Day 5, moderate on Day 11, and minimal on subsequent days. In situ hybridization signals in uterine glandular epithelial cells remained high from Day 5 to Day 13, with weaker signals thereafter. Quantitative reverse transcription-PCR (RT-qPCR) assays were used for quantitation of FUT1 and FUT2 mRNAs. Quantitative RT-qPCR data were generated from endometrium collected from cyclic and pregnant animals on Days 5, 11 and 17. Relative levels of FUT1 mRNA were high on Days 5 and 11, but then fell 5-fold by Day 17 (P < 0.01). FUT2 mRNA concentrations were below the accurate detectable limit of the assay. High levels of HT1 were observed on the apical surface of uterine luminal epithelia on Days 5, 15, 17 and 19, with much lower levels on Days 11 and 13. Thus, data suggests that FUT1 is the primary enzyme responsible for the high levels of HT1 antigen present on the uterine luminal epithelium between Days 5 and 11 of the estrous cycle and early pregnancy. But changes in the expression of the FUT1 gene does not directly correlate to HT1 staining, which increased from Day 13–15. Future studies are required to understand the regulation of the HT1 antigen on the luminal surface of endometrium.