Acúmulo e desaparecimento de forragem e variações na estrutura de pastos de capim-xaraés submetidos a intensidades de pastejo em lotação intermitente

The aim of this study was to evaluate the effects of residual leaf area index (rLAI), years of evaluation and grazing cycles on the accumulation and disappearance of forage, and changes in the pasture structure of xaraes palisadegrass submitted to grazing intensities and intermittent stocking in two summers. The experiment was carried out at the Faculdade de Ciencias Agrarias e Veterinaria of Unesp, Campus of Jaboticabal, SP and the intensities of grazing were defined by four rLAI: 0.8, 1.3, 1.8 and 2.3. When the canopy intercepted 95% of incident light, the animals were placed on the pasture for grazing and kept until the rLAI target has been reached. Pastures were grazed by non-lactating Holstein cows (Bos Taurus Taurus L.), using the technique of mob-stocking. It was evaluated the canopy height, accumulation, disappearance and morphological components of forage and rest period. Residual leaf area index from 1.3 to 1.8 are the best in the accumulation and disappearance of forage and pasture structure. It is observed variability of the accumulation and disappearance of forage and pasture structure for years of assessment and grazing cycles within each year.

Cana-de-açúcar hidrolisada para vacas em lactação

Pós-graduação em Zootecnia - FCAV

Retenção de placenta no proteinograma de vacas Holandesas

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

Controle e estimulação de crescimento folicular em doadoras da raça holandesa para a produção in vitro de embriões

Pós-graduação em Medicina Veterinária - FCAV

Perfil de fatores de virulência das Escherichia coli isoladas do útero de vacas holandesas após o parto e sua relação com a microbiota uterina

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

Avaliação das características do líquido ruminal associada à termografia digital e atividade pedométria em vacas holandesas

Pós-graduação em Medicina Veterinária - FMVZ

Aplicação de modelos de regressão aleatória utilizando diferentes estruturas de dados

A total of 3.035 lactations of Holstein cows from four farms in the Southeast, to check the influence of data structure of milk yield on the genetic parameters. Four dataset with different structures were tested, weekly controls (CW) with 122.842 controls, monthly controls (CM) 30.883, bimonthly controls (CB) with 15,837 and quarterly controls (CQ) with 12,702. The random regression model was used and was considered as random additive genetic and permanent environment effects, fixed effects of the contemporary groups (herd-year-month of test-day) and age of cow (linear and quadratic effects). Heritability estimates showed similar trends among the data files analyzed, with the greatest similarity between dataset CS, CM and CB. The dataset submitted all the CB estimates of genetic parameters analyzed with the same trend and similar magnitude to the CS and CM dataset, allowing the claim that there was no influence of the data structure on estimates of covariance components for the dataset CS, CM and CB. Thus, milk recording could be accomplished in a CB structure.

Pharmacokinetics of tetracycline in plasma, synovial fluid and milk using single intravenous and single intravenous regional doses in dairy cattle with papillomatous digital dermatitis

The purpose of this study was to compare the pharmacokinetics of tetracycline in plasma, synovial fluid, and milk following either a single systemic intravenous (i.v.) injection or a single i.v. regional antibiosis (IVRA) administration of tetracycline hydrochloride to dairy cattle with papillomatous digital dermatitis (PDD). To this end, plasma and synovial fluid tetracycline concentrations were compared with the minimal inhibitory concentration (MIC) values of the major bacteria, which are known to cause digital diseases and thus assess its efficacy in PDD. Residual tetracycline concentrations in milk from cows treated by both methods were also determined. Twelve Holstein cows with various stages of PDD were randomly assigned to two groups of six animals. Group 1 received a single systemic i.v. injection of 10 mg/kg of tetracycline hydrochloride. Group 2 received 1000 mg of tetracycline hydrochloride by IVRA of the affected limb. Blood, synovial fluid and milk samples were taken prior to tetracycline administration (time 0 control), and then at 22, 45 and 82 min, and 2, 3, 4, 6, 8, 12, 24, 48, 72, 96, and 120 h following drug administration. Tetracycline concentrations were determined by high-performance liquid chromatography. Mean tetracycline plasma and milk concentrations in Group 1 were higher than Group 2. The opposite was observed for synovial fluid concentrations. Group 2 synovial fluid concentrations were higher than the MIC value over 24 h for the bacteria most frequently responsible for claw disease. Compared with i.v. administration, IVRA administration of tetracycline produced very high synovial fluid and low plasma and milk concentrations.

Reaction norm model to describe environmental sensitivity across first lactation in dairy cattle under tropical conditions

Reaction norm models have been widely used to study genotype by environment interaction (G × E) in animal breeding. The objective of this study was to describe environmental sensitivity across first lactation in Brazilian Holstein cows using a reaction norm approach. A total of 50,168 individual monthly test day (TD) milk yields (10 test days) from 7476 complete first lactations of Holstein cattle were analyzed. The statistical models for all traits (10 TDs and for 305-day milk yield) included the fixed effects of contemporary group, age of cow (linear and quadratic effects), and days in milk (linear effect), except for 305-day milk yield. A hierarchical reaction norm model (HRNM) based on the unknown covariate was used. The present study showed the presence of G × E in milk yield across first lactation of Holstein cows. The variation in the heritability estimates implies differences in the response to selection depending on the environment where the animals of this population are evaluated. In the average environment, the heritabilities for all traits were rather similar, in range from 0.02 to 0.63. The scaling effect of G × E predominated throughout most of lactation. Particularly during the first 2 months of lactation, G × E caused reranking of breeding values. It is therefore important to include the environmental sensitivity of animals according to the phase of lactation in the genetic evaluations of Holstein cattle in tropical environments.

Estresse calórico sobre a luteólise de vacas holandesas não lactantes

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

The manipulation of progesterone profiles during progesterone + estradiol timed ai protocols in dairy cattle: effects on fertility

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

Proteinograma sérico de bezerros recém-nascidos alimentados com colostro de vacas com mastite

The aim of this study was to evaluate the serum protein concentration in newborns fed with colostrum derived from healthy cows (n = 10), cows with subclinical mastitis (n = 10) and cows with clinical mastitis (n = 10). 30 Holstein cows were assigned to their respective groups according to macroscopic examination of colostral secretion, somatic cell count, CMT and presence of bacteria in colostrum samples. Blood samples of the calves were collected immediately after birth, at 24 and 48 hours after ingestion of colostrum. The total protein was measured by the biuret method and the concentrations of immunoglobulin A (IgA), immunoglobulin G (IgG), transferrin, albumin and haptoglobin was determined by sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE). No differences were obser- ved amongst groups in the concentrations of albumin, total protein and IgA. In animals from cows with subclinical and clinical mastitis haptoglobin concentrations were higher than those of healthy animals. The concentrations of IgG and transferrin were significantly lower in calves from cows with mastitis. We concluded that the ingestion of colostrum from infected and uninfected glands from cows with mastitis (GII e GIII) is unlikely to be an important contributor to the high rate of failure of passive transfer of immunoglobulins in calves.

Óleo funcional na dieta de vacas leiteiras

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Efeito da adição de vesículas extracelulares intrafoliculares de vacas holandesas submetidas ao estresse térmico em meio de maturação oocitária in vitro

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Fatores que afetam a expressão de estro detectado por monitores de atividade e riscos de concepção em vacas leiteiras lactantes

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)