Modelos bayesianos para análise de características reprodutivas de fêmeas Nelore

Pós-graduação em Genética e Melhoramento Animal - FCAV

Effects of calcium salts of soybean oil on factors that influence pregnancy establishment in Bos indicus beef cows

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Accuracy of genomic predictions in Bos indicus (Nellore) cattle

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Genome-wide association analysis of feed intake and residual feed intake in Nellore cattle

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Analysis of the risk factors relating to cows' resistance to Rhipicephalus microplus ticks during the peripartum

This study aimed to evaluate season, breed, number of lactations and milk production as risk factors relating to Rhipicephalus microplus infestation in dairy cows during the peripartum. Eighty-four animals were randomly selected through proportional stratified sampling. All engorged and partially engorged female R. microplus specimens measuring 4.5-8.0 mm were counted during the 5 weeks before calving, calving week and 5 weeks after calving. The peripartum had a significant effect [calving (p < 0.05; prevalence ratio (PR)= 3.12) and post calving (p < 0.05; PR = 2.02)] on R. microplus infestation. Although the average tick count was higher during the rainy season than during the dry season, there was no significant difference (p = 0.055; PR = 0.63). The average R. microplus count was significantly higher (p < 0.05; PR = 2.10) in Bos taurus animals, followed by F1 (p < 0.05; PR = 1.64) and Girolando (p < 0.05; PR = 1.39). The average R. microplus count was significantly higher (p < 0.05; PR = 0.97) in first-lactation animals, followed by those at the second, third and, fourth or subsequent lactation. Milk production showed a negative correlation with R. microplus count, such that high-production animals were significantly (p = 0.003; PR = 2.04) more vulnerable to infestation than were low-production animals. First-lactation and high-production B. taurus animals had greatest vulnerability to R. microplus infestation over the peripartum period, and constituted the at-risk group in the dairy herd.u

Genome-wide association study for feedlot average daily gain in Nellore cattle (Bos indicus)

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Immunocastration improves carcass traits and beef color attributes in Nellore and Nellore x Aberdeen Angus crossbred animals finished in feedlot

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

In vivo embryo production in cows superovulated 1 or 2 days after ovum pick-up

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Inducing ovulation early postpartum influences uterine health and fertility in dairy cows

The objective of the current study was to evaluate the effect of GnRH early postpartum on induction of ovulation, uterine health, and fertility in dairy cows. Holstein cows without a corpus luteum (CL) at 17 +/- 3 DIM were assigned randomly to receive i.m. GnRH (n = 245) at 17 +/- 3 and 20 +/- 3 DIM or remain as controls (n = 245). Ovaries were scanned by ultrasonography twice weekly totaling 4 examinations. Ovulation was characterized by the appearance of a CL >= 20 mm at any ultrasound or CL <20 mm in 2 consecutive examinations. Clinical and cytological endometritis were diagnosed at 35 DIM. Compared with control, GnRH increased ovulation up to 3.5 d after the last treatment (78.7 vs. 45.0%) and did not affect the prevalence of clinical endometritis (23.9 vs. 18.6%) or cytological endometritis (30.9 vs. 32.8%). Prevalence of clinical endometritis increased in cows that had calving problems (32.6 vs. 15.9%) and metritis (40.6 vs. 15.8%). Metritis increased prevalence of cytological endometritis (50.7 vs. 23.5%). Treatment with GnRH did not affect pregnancy per artificial insemination at 32 (37.6 vs. 38.6%) or 74 d after artificial insemination (35.0 vs. 31.5%), but reduced pregnancy loss (6.8 vs. 18.1%). No overall effect of GnRH treatment on hazard of pregnancy was observed; however, an interaction between GnRH treatment and ovulation showed that GnRH-treated cows that ovulated had increased hazard of pregnancy by 300 DIM compared with GnRH-treated and control cows that did not ovulate (hazard ratio = 2.0 and 1.3, respectively), but similar to control cows that ovulated (hazard ratio = 1.1). Gonadotropin-releasing hormone early postpartiim induced ovulation without affecting uterine health, but failed to improve pregnancy per artificial insemination or time to pregnancy, although it reduced pregnancy loss.

Manipulation of the periovulatory sex steroidal milieu affects endometrial but not luteal gene expression in early diestrus Nelore cows

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Risk factors for anaplasmosis in dairy cows during the peripartum

Anaplasma marginale is endemic in tropical and subtropical areas around the world. Some studies have suggested that cows during peripartum may present a transient immunosuppression state and development of clinical signs of anaplasmosis. The aim of this study was to investigate the relationship between some risk factors and the seroprevalence of A. marginale in dairy cows during peripartum in Rio de Janeiro, Brazil. The risk factors analyzed in association with the prevalence of antibodies against A. marginale in dairy cows were calving season, reproductive experience, breed standard, tick infestations, stocking density, and milk yield. The antibodies against A. marginale were tested in indirect enzyme-linked immunosorbent assays. A primary screening using a 2 x k contingency table of the exposed variables with the outcomes was performed. All variables for which p < 0.20 were included in a fixed effects log regression. The risk factors investigated to anaplasmosis were calving (OR 2.61, IC 1.08-7.63), breed standard (OR 3.83, IC 0.08-0.28), reproductive experience (OR 33.7, IC 2.14-5.16), milk yield (OR 3.9, IC 2.24-7.03), Rhipicephalus microplus infestations (OR 10.3, IC 0.05-0.17), and stocking density (OR 22.3, IC 0.05-0.17). Low titers of antibodies against A. marginale during peripartum had been characterized as a period previous to development of clinical anaplasmosis. Thus, studies on anaplasmosis should consider each farm as an epidemiological unit, where environmental and immunological factors may influence the endemic status of the pathogen.

Reducing supplementation frequency for Nellore beef steers grazing tropical pastures

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Effect of lipid sources with different fatty acid profiles on the intake, performance, and methane emissions of feedlot Nellore steers

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)