CARACTERIZAÇÃO DO STAPHYLOCOCCUS COAGULASE NEGATIVO ISOLADOS DE QUARTOS MAMÁRIOS DE VACAS COM MASTITE SUBCLÍNICA

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

Rumen microbial diversity under influence of a polyclonal antibody preparation against lactate-producing and proteolytic bacteria in cows fed different energy sources

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

Random regression models to estimate genetic parameters for milk production of Guzerat cows using orthogonal Legendre polynomials

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

Plasma anti-mullerian hormone: an endocrine marker for in vitro embryo production from Bos taurus and Bos indicus donors

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

Predicting breeding values for milk yield of Guzera (Bos indicus) cows using random regression models

Given the importance of Guzera breeding programs for milk production in the tropics, the objective of this study was to compare alternative random regression models for estimation of genetic parameters and prediction of breeding values. Test-day milk yields records (TDR) were collected monthly, in a maximum of 10 measurements. The database included 20,524 records of first lactation from 2816 Guzera cows. TDR data were analyzed by random regression models (RRM) considering additive genetic, permanent environmental and residual effects as random and the effects of contemporary group (CG), calving age as a covariate (linear and quadratic effects) and mean lactation curve as fixed. The genetic additive and permanent environmental effects were modeled by RRM using Wilmink, All and Schaeffer and cubic B-spline functions as well as Legendre polynomials. Residual variances were considered as heterogeneous classes, grouped differently according to the model used. Multi-trait analysis using finite-dimensional models (FDM) for testday milk records (TDR) and a single-trait model for 305-days milk yields (default) using the restricted maximum likelihood method were also carried out as further comparisons. Through the statistical criteria adopted, the best RRM was the one that used the cubic B-spline function with five random regression coefficients for the genetic additive and permanent environmental effects. However, the models using the Ali and Schaeffer function or Legendre polynomials with second and fifth order for, respectively, the additive genetic and permanent environmental effects can be adopted, as little variation was observed in the genetic parameter estimates compared to those estimated by models using the B-spline function. Therefore, due to the lower complexity in the (co)variance estimations, the model using Legendre polynomials represented the best option for the genetic evaluation of the Guzera lactation records. An increase of 3.6% in the accuracy of the estimated breeding values was verified when using RRM. The ranks of animals were very close whatever the RRM for the data set used to predict breeding values. Considering P305, results indicated only small to medium difference in the animals' ranking based on breeding values predicted by the conventional model or by RRM. Therefore, the sum of all the RRM-predicted breeding values along the lactation period (RRM305) can be used as a selection criterion for 305-day milk production. (c) 2014 Elsevier B.V. All rights reserved.

Inferences of body energy reserves on conception rate of suckled Zebu beef cows subjected to timed artificial insemination followed by natural mating

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

Temporal analysis of prostaglandin F2 alpha receptor, caspase 3, and cyclooxygenase 2 messenger RNA expression and prostaglandin F2 alpha receptor and cyclooxygenase 2 protein expression in endometrial tissue from multiparous Nelore (Bos taurus indicus) cows treated with cloprostenol sodium during puerperium

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

Methicillin-resistant Staphylococcus aureus of lineage ST398 as cause of mastitis in cows

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Impact of Probing the Reproductive Tract During Early Pregnancy on Fertility of Beef Cows

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

Sexual Precocity of Nellore Bulls that are Offspring of Super Precocious, Precocious and Normal Cows in Extensive Farming Conditions

Contents The objective of this work was to verify that mothers classified as super precocious (M1) and precocious (M2) produce more precocious bulls than females classified as normal (M3). This study included 21186 animals with an average age of 21.29 +/- 1.77months that underwent a breeding soundness evaluation from 1999 to 2008. Of these animals, 2019, 6059 and 13108 were offspring of M1, M2 and M3 females, respectively. In the breeding soundness examination, the animals were classified as sound for reproduction, sound under a natural mating regime, unsound for reproduction and discarded. To compare the averages obtained for each category of mother within the individual breeding soundness classes, a chi-square test with a 5% error probability was used, considering the effects of year and month of birth and farm. For the three classes of mothers (M1, M2 and M3), 67.26, 67.22 and 64.16% of bull calves were considered sound for reproduction and 19.71, 19.46 and 21.90% were considered unsound for reproduction, respectively. There was no difference in the frequency of animals that were sound for reproduction under the natural breeding regime between the three classes of mothers (8.87, 9.31 and 9.19%, respectively). There was a difference between the numbers of precocious and normal females that were discarded, with frequencies of 4.01 and 4.75%, respectively (p<0.05). There were differences in year and month of birth and farm between super precocious and precocious cows in relation to the breeding soundness classification of the animals. It was concluded that the bull offspring of super precocious and precocious cows presented a higher percentage of approval in the breeding soundness examination than the bull offspring of normal cows, demonstrating that the selection for precocity of females has contributed to an increase in the sexual precocity of the herd in relation to the sexual maturity of bulls.

The physiology and impact on fertility of the period of proestrus in lactating dairy cows

In cattle, proestrus begins with the initiation of luteolysis and ends with initiation of estrus and the GnRH/LH surge. This period is marked by a dramatic decrease in circulating progesterone (P4) that reaches a nadir by about 36-48 h in cows undergoing natural or prostaglandin F2 alpha (PGF)-induced luteolysis. Inadequate luteolysis is a cause of reduced fertility particularly in timed AI programs with small elevations in circulating P4 reducing fertility. Increasing circulating estradiol (E2) during proestrus is dependent on presence, size, and function of the dominant follicle and this varies during natural proestrus, due to whether animals have two or three follicular waves, and during PGF-induced proestrus, according to stage of the follicular wave at time of PGF treatment. Inadequate circulating E2 can limit fertility and increase pregnancy loss in some specific circumstances such as in cows with low BCS and in cows during heat stress. Thus, studies to optimize the length of proestrus and the concentrations of E2 and P4 during proestrus could produce substantial improvements in fertility and reductions in pregnancy loss.

Estresse término na reprodução de vacas leiteiras

Climate change in tropical countries, like Brazil, causes major problems in dairy production due to an increase of heat stress effects. In recent years, milk production in Brazil increased 36.07%. The Southeast region remains a leader in production with herds of high producing Holstein cattle (mostly), which is more susceptible to heat stress. Thermal stress decreases fertility in direct and indirect ways. Conception rates are reduced of 40-60% during cooler months of the year and 10-20% in the warmer months. Negative effects of heat stress involve changes in reproductive hormones, follicular development, oocytes, and embryos, and decreased dry matter intake. Several studies discuss change in reproductive hormones, such as reduction in plasma concentration of GnRH, LH, and oestradiol, which lead to decreased detection of estrus and ovulation. Various methods are being studied to bypass these negative effects and increase the fertility of dairy cows under heat stress. Cooling systems are the most advantageous and can be associated with technologies such as ET and TAI

Uso de microarray para determinação da expressão gênica diferencial em oócitos Bos Taurus Indicus e Bos Taurus Taurus submetidos ao estresse térmico

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Fontes de ácidos graxos insaturados na alimentação de vacas leiteiras no período seco

Pós-graduação em Zootecnia - FCAV

Ovarian superstimulation using FSH combined with equine chorionic gonadotropin (eCG) upregulates mRNA encoding proteins involved with LH receptor intracellular signaling in granulosa cells from Nelore cows

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