An equation based on heat transfer theory was presented to estimate the rate of heat loss from cattle exposed to a tropical environment, specified by the air temperature, humidity, solar radiation, and wind speed. The animals’ variables (sweating rate, rectal temperature, respiratory rate, surface temperature, haircoat color, and body weight) were considered together with environmental variables (air temperature and humidity, solar radiation, wind speed, and globe temperature). The equation allows the prediction of (a) the metabolic heat production level necessary […]

The work was carried out to evaluate the microbial protein production determination by means of the urinary excretion of purine derivatives; to compare the microbial protein production by means of purine base methods and of the urinary excretion of purine derivatives; to determine the microbial protein production on the dry matter intake and percentage of neutral detergent fiber in the diet; and to establish the allantoin: uric acid ratio, in relation to the xanthine and hypoxanthine in the urine. Five […]

The objective of this experiment was to study the carcass traits and their correlation with the tissue composition. Twenty-two intact male lambs, sired by Texel males, from crossbreed Texel -Ideal dams were used. At the beginning of the experiment (24 hours after birth), four lambs were slaughtered to serve as reference and a group of six lambs were slaughtered at weaning time and at 28 and 33 kg LW. The lambs were confined in individual stall with their respective mothers […]

This work was conducted with the objective to determine the body composition for fat, protein and ash, the net requirements of energy and protein for weight gain, and the requirements of metabolizable protein of growing lambs. Twenty-two male lambs, sired by Texel males, from crossbreed Texel x Ideal dams were used. Four lambs were slaughtered at the beginning of the experiment (24 hours after birth) and groups of six lambs were slaughtered at weaning, at 28 and 33 kg of […]

The objective of the present work was to validate the ruminal and post-ruminal nutrient dynamics and the ruminal microbial growth predictions, by using the equations of the Cornell system. The experiment was carried out during the rainy and dry seasons of the 1996 year, in a natural pasture area situated in the county of Viçosa (MG). Esophageally, ruminally and abomasally cannulated steers were used during two experimental periods within each season, and external markers (Cr2O3 and Eu) were used to […]

The objectives of the present work were to characterizate and determinate the parameters estimates related to the ruminal degradation kinetics of the carbohydrates in extrusa samples from animals maintained in a natural pasture of the Zona da Mata (MG) region, during the rainy and dry seasons of the year. To obtain representative samples, four esophageal fistulated steers were used in two experimental periods during the rainy season, and three of these animals were used in two experimental periods during the […]

An experiment was conducted, on extraction and analysis of n-alkanes, to investigate the use of n-alkane (C35) present in forages as an internal marker for the digestibility determination. Samples of forages and feces were taken from conventional digestibility trials, which were previous conducted from 1978 to 1982. The C35 underestimated the dry matter and organic matter digestibilities, presenting an average difference in relation to in vivo of 4.68 (± 0.69) and 4,43 (± 0.85) perceptual units, respectively. The coefficient of […]

The effects of dietary concentrate levels were evaluated on the microbial synthesis efficiency, the nitrogenous compounds balance, the ammonia concentrations and the ruminal fluid pH, the ruminal digesta passage rate and the endogenous losses of nitrogen compounds (N). Five F1 Simental x Nellore bulls fistulated in the rumen, abomasum and ileum, full fed diets with 25.0; 37.5; 50.0; 62.5; and 75.0% of concentrate and allotted to 5×5 Latin square, were used. The ammonia concentrations and the ruminal pH were determined […]

Fifty-one postpartum Nellore cows were used to study the effect of the utilization of protein concentrate, during the summer time, on the forage intake, weight gain and body condition score changes after parturition of Nellore cows. The animals were randomly allotted in the following treatments: T0 – without supplementation; T1 – supplemented with 1 kg and T2 – supplemented with 2 kg of concentrate with 40.8% of crude protein, during 105 days. During this period, body score and body weight […]

The digestibilities of dry matter (DM), crude protein (CP), ether extract (EE), neutral detergent fiber (NDF), gross energy (GE) and total digestible nutrients (TDN) were determined by using four internal markers (acid detergent fiber – ADF and lignin and acid insoluble ash – AIA). The three first markers were submitted to in vitro disappearance for three and six days and the results were compared with data determined by total feces collection. The nutrient digestibility estimated by NDF, ADF and lignin […]