Evaluation of the effects of sire and dam calving group on age at first calving in Brahman heifers

Earnhardt, Audrey L; Neuendorff, D.A.; Long, C. R.; Welsh, T. H.; Randel, R.D.

doi:10.1016/j.theriogenology.2021.03.005

Cited by 3 publications

(3 citation statements)

References 16 publications

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“…Selection for early‐calved bulls could have a big contribution to the livestock industry. Indeed, a recent study showed that selection for Brahman heifers capable of calving early is more effective from the sire side than the dam side (Earnhardt et al, 2021). Therefore, efforts should be made to implement this trait into beef genetic programs because it could also favourably impact female fertility and the stayability in the herd.…”

Section: Discussionmentioning

confidence: 99%

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Calving date as a potential predictor for the probability of approval in the first breeding soundness evaluation of Nellore bulls

Diaz-Miranda

Penitente-Filho

Gomez-León

et al. 2023

Reprod Domestic Animals

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Beef production systems primarily use natural service (NS) for breeding. However, a significant number of bulls used for NS are subfertile, limiting the profitability of the cow‐calf operations. Therefore, producers should select bulls based on breeding soundness evolutions (BSE) to ensure higher pregnancy rates. Several factors can affect the bull ability to pass a BSE. We hypothesize that calving date would be a factor that affects the bull probability of approval at the first BSE. For this purpose, a multivariate logistic regression in a dataset of 14,737 BSEs from young Nellore bulls was used. Correlations between calving date, biometrics, and semen traits were evaluated using Pearson's correlation coefficient. Our results demonstrated that the calving date affected the probability of approval at the first BSE (p < .05). Indeed, the variable that added more information to our model was the calving date, far more than the age group of the bulls according to Akaike's information criterion. Hence, bulls born on day 0 of the calving season have 1.26 more chances to be approved at the first BSE than bulls born 21 days later. This result highlights the importance of getting the dams of future bulls pregnant as soon as possible in the breeding season. In addition, the calving season should be no longer than 47 days to achieve 80% BSE approval in 20–22 months old Nellore bulls. The strongest correlation was with SC, which decreased as the calving date increased. Therefore, the calving date may be used as a predictor of the outcome of the first BSE in young bulls. In that way, the calving date can help seedstock producers to maximize efficiency in making crucial management decisions during the breeding and calving season including nutrition, reproductive, and culling.

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Section: Discussionmentioning

confidence: 99%

“…Selection for early-calved bulls could have a big contribution to the livestock industry. Indeed, a recent study showed that selection for Brahman heifers capable of calving early is more effective from the sire side than the dam side (Earnhardt et al, 2021).…”

Section: Ta B L E 2 Comparison Of Akaike Information Criterion (Aic)mentioning

confidence: 99%

Calving date as a potential predictor for the probability of approval in the first breeding soundness evaluation of Nellore bulls

Diaz-Miranda

Penitente-Filho

Gomez-León

et al. 2023

Reprod Domestic Animals

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“…In this context, it is important to mention that cow and bull fertility are favorably genetically correlated; therefore, cow fertility could be genetically improved by indirect selection on bull fertility (Mackinnon et al, 1990). Indeed, a recent study showed that the best way to select for calving date was through the father side, instead of the mother side in order to increase the production of Brahman heifers (Earnhardt et al 2021). Calving date is the day within the calving season in which the heifer or cow calved (Cammack et al, 2009); it is one of the key reproductive traits in beef genetic programs because its high heritability and has an economic impact .…”

Section: Genetic Relationships With Reproductive Traitsmentioning

confidence: 99%

Predictors of success in the breeding soundness evaluation and infertility in bulls

Miranda¹

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Bull fertility is critical for the profitability and sustainability of the cattle industry. To date, the Breeding soundness evaluation (BSE) is the best methodology to estimate the reproductive potential of future bulls. However, the guidelines for the BSE differ between practitioners and societies, perhaps due to a lack in research in this area. Therefore, our first study hypothesized that by the implementation and use of strict BSE guidelines the number of approved Nellore bulls and their reproductive quality would increase overtime. Furthermore, our second study hypothesized that bulls born early in the calving season are more likely to be approved in their first BSE when compared to males calved later. To evaluate these two hypotheses, records of 20 years and 46,566 BSE were used in two separate analyses including a multivariate logistic regression to measure the effect of the year and farm, and to predict the probability of approval in Nellore young bulls at their first BSE according to their dams calving date. Bulls were classified as approved (satisfactory potential breeders and qualified for natural breeding service) and not approved (deferred and unsatisfactory potential breeders). Overall, there was no improvement in the percentage of approved bulls. However, there was an increase in the number of bulls approved in the first BSE and an increase in the percentage of bulls classified as satisfactory potential breeders (P-value <0.05), which means that the quality of the bulls improved over time. On the other hand, it was demonstrated that the calving date affected the probability of approval at the first BSE. Hence, bulls born on day 0 of the calving season had 1.26 more chances to be approved at the first BSE than bulls born 21 days later. In our studies, 53% of the bulls were not approved due to poor sperm quality, specifically abnormal sperm morphology. Bull ejaculates with the aplastic midpiece defect (AMD) have poor motility and fertility and it’s related to have a putative genetic origin. Therefore, our third study aimed to understand the origin and factors contributing to the abnormal sperm production of the AMD in Dairy Gyr bulls. Six Dairy Gyr Bulls (three control bulls and three bulls with AMD) obtained from the same farm and management were castrated to conduct a sperm morphofunctional and proteomic study and evaluate the redox state of reproductive tissues. The morphological analysis demonstrated that the AMD is a consequence of defective spermiogenesis. Control bulls also produced a high percentage of AMD but have an effective mechanism of removal of the defective sperm prior to epididymal transit. This mechanism generates mild oxidative stress in the testis and caput of the epididymis (measured as MDA and CAT; P-value <0.05); however, the redox state was reestablished in the corpus and cauda of the epididymis. Furthermore, qualitative and quantitative proteomic analysis showed that the sperm maturation of the bulls with the AMD should be deficient once they had differences in protein expression and a poor enrichment of critical pathways for sperm fertility. Finally, our last study hypothesized that binder of sperm (BSP) proteins could be used as a potential biomarker of defective sperm. Therefore, we characterized the binding properties and abundance of the BSP proteins after discontinuous gradient centrifugation and found that; in the supernatant fractions, there was an increase of BSP proteins abundance when compared to the sperm pellet fractions (P- value <0.05). In the sperm pellet fractions, BSP1 and BSP3 bound predominately to the acrosomal region of the sperm head, whereas BSP5 had a high affinity for the midpiece. Furthermore, high BSP proteins abundance was found to be correlated with acrosome and membrane damage induced by permeabilization. Therefore, the abundance of BSP proteins could be used as biomarker of defective sperm or sperm with compromise function. Our results allowed us to complement the knowledge on bull fertility, from the basic but functionally BSE to biomarkers for defective sperm specially on Bos indicus cattle. Keywords: Bull fertility. Sperm morphology. BSPs. Biomarkers.

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Effect of sires’ expected progeny difference for scrotal circumference and juvenile ADG on the puberty of crossbred beef heifers

Barroso

Ferraz

Oliveira

et al. 2023

Trop Anim Health Prod

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Evaluation of the effects of sire and dam calving group on age at first calving in Brahman heifers

Cited by 3 publications

References 16 publications

Calving date as a potential predictor for the probability of approval in the first breeding soundness evaluation of Nellore bulls

Calving date as a potential predictor for the probability of approval in the first breeding soundness evaluation of Nellore bulls

Predictors of success in the breeding soundness evaluation and infertility in bulls

Effect of sires’ expected progeny difference for scrotal circumference and juvenile ADG on the puberty of crossbred beef heifers

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