Bovine follicular fluid (FF) constitutes the microenvironment of follicles and includes various biologically active proteins. We performed a study involving 18 healthy nonlactating Holstein cows to determine the protein expression profile of FF at key stages of follicular development. Follicles were individually aspirated in vivo at predeviation (F1 ∼ 7.0 mm), deviation (F1 ∼ 8.5 mm), postdeviation (F1 ∼ 12.0 mm), and preovulatory stages of follicle development, which were confirmed by measurement of follicular estradiol and progesterone concentrations. The FFs from nine cows were selected for proteomic analysis. After albumin depletion, triplicates of pooled FF were reduced, alkylated, and digested with trypsin. The resulting peptides were labeled with TMTsixplex and quantified using liquid chromatography-mass spectrometry/mass spectrometry. A total of 143 proteins were identified and assigned to a variety of biological processes, including response to stimulus and metabolic processes. Twenty-two differentially (P < 0.05) expressed proteins were found between stages indicating intrafollicular changes over development, with expected deviation time critical to modulate the protein expression. For instance, high concentrations of follistatin, inhibin, serglycin, spondin-1, fibrinogen, and anti-testosterone antibody were found during early stages of follicular development. In contrast, apolipoprotein H, alpha-2-macroglobulin, plasminogen, antithrombin-III, and immunoglobulins were increased after deviation. Among the differentially abundant proteins, 19 were found to be associated with steroidogenesis. Pathway analysis identified proteins that were mainly associated with the acute phase response signaling, coagulation system, complement system, liver/retinoid X receptor activation, and biosynthesis of nitric oxide and reactive oxygen. The differentially expressed proteins provide insights into the size-dependent protein changes in the ovarian follicle microenvironment that could influence follicular function.

Heat stress (HS) adversely influences productivity and welfare of dairy cattle. We hypothesized that the thermoregulatory mechanisms vary depending on the exposure time to HS, with a cumulative effect on the adaptive responses and thermal strain of the cow. To identify the effect of HS on adaptive thermoregulatory mechanisms and predictors of caloric balance, Holstein cows were housed in climate chambers and randomly distributed into thermoneutral (TN; n=12) or HS (n=12) treatments for 16 days. Vaginal temperature (VT), rectal temperature (Tre), respiratory rate (RR), heart rate (HR), and dry matter intake (DMI) were measured. The temperature and humidity under TN were 25.9±0.2°C and 73.0±0.8%, respectively, and under HS were 36.3±0.3°C and 60.9±0.9%, respectively. The RR of the HS cows increased immediately after exposure to heat and was higher (76.02±1.70bpm, p<0.001) than in the TN (39.70±0.71bpm). An increase in Tre (39.87±0.07°C in the HS vs. 38.56±0.03°C in the TN, p<0.001) and in VT (39.82±0.10°C in the HS vs. 38.26±0.03°C in the TN, p<0.001) followed the increase in RR. A decrease (p<0.05) in HR occurred in the HS (62.13±0.99bpm) compared with the TN (66.23±0.79bpm); however, the magnitude of the differences was not the same over time. The DMI was lower in HS cows from the third day (8.27±0.33kgd in the HS vs. 14.03±0.29kgd in the TN, p<0.001), and the reduction of DMI was strongly affected (r=-0.65) by changes in the temperature humidity index. The effect of environmental variables from the previous day on physiological parameters and DMI was more important than the immediate effect, and ambient temperature represented the most determinant factor for heat exchange. The difference in the responses to acute and chronic exposure to HS suggests an adaptive response. Thus, intense thermal stress strongly influence thermoregulatory mechanisms and the acclimation process depend critically on heat exposure time.

ResumoObjetivou-se com este estudo estimar índices de desempenho zootécnico e econômico de referência, analisar a influência dos tipos de mão de obra sobre a rentabilidade da atividade e identificar os componentes que exerceram maiores representatividades sobre o custo total e operacional efetivo. Foram analisados 38 índices de tamanho, zootécnico e econômico de 61 sistemas de produção de leite, localizados em Minas Gerais e Rio de Janeiro, agrupados em função do tipo de mão de obra. Os dados foram coletados durante o período de janeiro de 2002 a dezembro de 2011. Os resultados foram comparados pelo teste de ANOVA (distribuição normal), complementado pelo teste LSD, e pelo teste de Kruskal-Wallis (distribuição não normal), também complementado pelo teste LSD. Índices de medição de desempenho de referências devem ser considerados, levando-se em conta os fatores que sejam comuns aos sistemas de produção. O tipo de mão de obra não parece determinar a eficiência econômica do sistema de produção. Os itens componentes do custo total e operacional efetivo que exerceram maiores representatividades foram, em ordem decrescente, alimentação e mão de obra, para os grupos mão de obra contratada e mista, e alimentação e despesas diversas, para o grupo mão de obra familiar. Palavras-chave: análise de rentabilidade; eficiência técnica; índices de referência; pecuária leiteira; recursos humanos. AbstractThe objective of this research was to estimate reference zootechnical and economic performance indices, evaluate the influence of different types of labor on the technical and economic results and identify the components that had greater representativeness on the total and effective operational cost of dairy farms. We analyzed 38 size, zootechnical, and economic indicators of 61 milk production systems, grouped according to the type of labor. The data were collected during January 2002 to December 2011 period. The results were compared by ANOVA test (normal distribution), complemented by LSD test, and Kruskal-Wallis test (nonnormal distribution), also complemented by LSD test. Reference performance indices should be considered, taking into account the factors that are common to dairy farms. The type of labor does not seem to determine

Animal production systems and agribusiness Full-length research article Association between technical and economic performance indexes and dairy farm profitability ABSTRACT-This study aimed to evaluate the determinant profitability indexes of typical dairy farms located in Brazil. The empirical sample included detailed technical and financial information of 61 Brazilian dairy farms across a longitudinal data set (10 years). Numerous technical and economic indexes were estimated, and Pearson's correlation coefficients were calculated to determine the relationship between each index and profitability. After selecting the significant indexes, regression equations were generated to determine the relationship between each index and profitability. The results of the analysis revealed significant interactions between different combinations of technical and financial indexes. Milk production per lactating cow and area were the indexes most positively correlated with profitability. In contrast, total unit cost in relation to the price of milk, total operating cost in relation to total revenues, and total unit operating cost in relation to the price of milk were the indexes most negatively correlated with profitability. Overall, these results indicate that profits could significantly increase if dairy farm production is conducted with more intensive use of inputs and production factors and better combinations of inputs and outputs.

ResumoObjetivou-se estimar índices de desempenho zootécnico e econômico de referência, analisar a influência de diferentes níveis tecnológicos sobre a rentabilidade da atividade leiteira e identificar os componentes que exerceram maiores representatividades sobre o custo total e operacional efetivo. Foram analisados 38 indicadores de tamanho, zootécnico e econômico de 61 sistemas de produção de leite, localizados em Minas Gerais e Rio de Janeiro, agrupados em função de três níveis tecnológicos. Os dados foram coletados durante o período de janeiro de 2002 a dezembro de 2011. Adotou-se a estrutura do custo operacional e do custo total como metodologia para apuração dos custos. Os resultados foram comparados pelo teste de ANOVA (distribuição normal), complementado pelo teste LSD, e pelo teste de Kruskal-Wallis (distribuição não normal), também complementado pelo teste LSD. A estratificação dos sistemas de produção em função do nível tecnológico pareceu não ser um bom critério para ser utilizado quando se deseja realizar comparações entre grupos distintos de produtores, evidenciado pela ausência de significância estatística (P>0,05) na comparação de índices de tamanho e zootécnico entre os grupos baixo e médio nível tecnológico. Os produtores de alto nível tecnológico fizeram investimentos sem as devidas análises de retorno sobre o investimento e risco. Os itens componentes do custo total e operacional efetivo que exerceram maiores representatividades foram, em ordem decrescente, alimentação e mão de obra. Palavras-chave: Análise de rentabilidade, custo de produção, índices de referência, lucratividade, pecuária leiteira AbstractThe objective of this study was to estimate reference zootechnical and economic performance indexes, examine the influence of different technological levels on technical and economic results on dairy farms and identify the components that had higher representativeness on total and effective operational cost. Thirty-eight size, zootechnical and economic indicators of 61 milk production systems, grouped according to three technological levels, were analyzed. The data were collected during January 2002 to December 2011 period. It was adopted the structure of the operating cost and the total cost as methodology for calculating the costs. The results were compared by ANOVA test (normal distribution),