Carlos Augusto de Alencar Fontes

Tamanho relativo dos órgãos internos de zebuínos sob alimentação restrita e Ad libitum

The effects of genetic group and nutritional level on relative size of internal organs were studied. Sixty-three bulls, 16 Gyr, 16 Guzera, 15 Nellore and 16 Mocho de Tabapua, averaging twenty four months of age, and initial live weight of 376.4, 357.6, 362.0, and 368.6 kg, respectively were used. The animals from each breed were randomly assigned to five groups. One group was immediately slaughtered (AB), three groups were full fed, in individual free stall, a diet containing 50% of concentrate on dry matter basis (group1, 2 and 3), and one group was fed with a restricted amount of the same diet to supply the levels of protein and energy 15% above maintenance (AR). The animals of groups 1, 2 and 3 were slaughtered when they reached the individual live weights of 405, 450 and 500 kg, respectively. At slaughter, the empty body weight (EBW) was determined and the weight of internal organs and viscera were recorded. There were no differences among breed regarding to weight of liver, spleen, small and large intestines, reticulo-rumen, omasum, stomach and gastrointestinal tract (GIT), per 100 kg of EBW. The feed restriction did not affect the weights of heart and lungs, but reduced the weight of liver and GIT components

Exigências de energia para mantença de bovinos zebuínos não-castrados em confinamento

The net requirements of energy for the maintenance of bulls from four Zebu breeds (Gyr, Guzera, Mocho-Tabapua and Nellore) were estimated with 63 bulls averaging 24 months of age and 366 kg initial LW and (15 Nellore and 16 from the Gyr, Guzera and Macho-Tapabua). Fifteen animals, four Gyr, Guzera and Mocho-Tabapua breed and three Nellore breed, were slaughtered at the beginning of the trial and the remaining were allotted to four groups of 12 animals, being three animals from each breed. One group was restricted fed, supplying levels of protein and energy 15,0% over maintenance requirements, according to NRC (1984). The animals of the last three groups were full fed to reach the target live weight slaughter of 405, 450 and 500 kg, respectively. A diet containing 50,0% concentrate as dry matter base and was fed individua lly to all animals. The net energy requirement for maintenance was determined as an estimation of heat production at zero metabolizable energy intake, by extrapolation of the regression equation of log of the heat production on the metabolizable energy intake. The estimated pooled net energy requirements for maintenance for the animals from the four breeds were 60.4 kcal/kgLW.75•day, 21.85%, lower than the value proposed by NRC (1996).

Composição corporal e exigências de macroelementos minerais (Ca, P, Mg, Na e K) de bovinos não-castrados de quatro raças Zebuínas

RESUMO - A composicao corporal e as exigencias de macroelementos minerais (Ca, P, Mg, Na e K) para ganho de peso de bovinos de quatro racas zebuinas (Gir, Guzera, Mocho-Tabapua e Nelore) foram estimadas com 63 animais nao-castrados, com idade media de 24 meses e 366 kg de PVinicial. Dezesseis animais das racas Gir, Guzera e Mocho-Tabapua e 15 da raca Nelore foram usados. Quinze animais, quatro das racas Gir, Guzera e Mocho-Tabapua e tres da Nelore, foram abatidos ao inicio do estudo e os demais, distribuidos em tres grupos, com tres animais de cada raca e alimentados individualmente, ad libitum, com racao contendo 50% de concentrado na materia seca, ate atingirem peso de abate de 405, 450 e 500 kg, respectivamente. Equacoes de regressao do logaritmo do conteudo corporal de macroelementos minerais, em funcao do logaritmo do corpo vazio (PCV), foram ajustadas para estimar os composicao corporal dos constituintes para qualquer PCV, dentro do intervalo incluido na pesquisa (250 a 450kg). Pela derivacao destas equacoes, a composicao do ganho de PCV foi obtida. Animais das quatro racas nao diferiram quanto a composicao corporal de macroelementos minerais e as exigencias liquidas para ganho de peso. Houve decrescimo na concentracao dos cinco macroelementos no PCV e no peso ganho, com a elevacao do PCV. As exigencias liquidas estimadas para ganho de PCV, para os cinco macrominerais, foram inferiores aos valores fixos sugeridos pelo ARC (1980). Os requerimentos liquidos estimados de Ca e P para ganho de peso de um bovino naocastrado de 400 kg PV foram 16 e 24% inferiores, respectivamente, aos propostos pelo AFRC (1991).

Body composition and energy and protein requirements for weight gain of bulls from four Zebu breeds

The body composition and the requirements for weight gain of energy and protein of cattle from four Zebu breeds (Gyr, Guzera, Mocho-Tabapua and Nellore) were estimated with 63 bulls averaging 24 months of age and 366 kg LW initial. Fifteen animals, four from Gyr, Guzera and Mocho-Tabapua breed and three from Nellore breed, were slaughtered at the beginning of the trial and the remaining were allotted to three groups, with three animals from each breed, which were individually full fed a diet containing 50% concentrate (%DM), to reach target live weights of 405, 450 and 500 kg, respectively. Regression of the log of body content in energy, fat, and protein on log of the empty body weight (EBW) was fitted to estimate the total body content of those constituents for any EBW inside the range included in the research (250 to 450 kg). By differentiation of those regressions, the composition of EBW weight gain was rejusted. The animals from the four breeds did not differ regarding to body composition of fat, protein and energy. The requirements of protein and net energy for the rejusted weight gains were similar to the adopted by NRC (1996) and the metabolizable energy as the adopted by AFRC (1993).

Utilização de método indireto para predição da composição química corporal de zebuínos

The objective of this study was to develop equations to predict chemical body composition from zebu cattle, based on chemical composition from carcass representative section. Sixty-three young bulls from Gyr, Guzera, Nellore and Mocho de Tabapuã breeds were used. Body content of protein, fat and minerals were determined on samples from the carcass section that included the 9th, 10th and 11th rib joint (HH joint), and from the remaining body tissues. Protein, fat, energy and ash contents from the HH joint, except for magnesium, were closely related to protein, fat, energy and ash contents in the body. Prediction equations based on chemical composition from HH joint showed to be reliable for comparative studies of body composition of zebu cattle.The objective of this study was to develop equations to predict chemical body composition from zebu cattle, based on chemical composition from carcass representative section. Sixty-three young bulls from Gyr, Guzera, Nellore and Mocho de Tabapua breeds were used. Body content of protein, fat and minerals were determined on samples from the carcass section that included the 9th, 10th and 11th rib joint (HH joint), and from the remaining body tissues. Protein, fat, energy and ash contents from the HH joint, except for magnesium, were closely related to protein, fat, energy and ash contents in the body. Prediction equations based on chemical composition from HH joint showed to be reliable for comparative studies of body composition of zebu cattle.

Produção de leite e desempenho dos bezerros de vacas Nelore e mestiças

The research was carried out to evaluate the lactation curves of Nellore and Crossbred F1 Limousin-Nellore (LN) and Simmental-Nellore (SN) cows and the performance of the progeny. Thirteen cows from each breed group, with age ranging from 5 to 9 years, and the respective calves were used. From 15 days after calving until weaning of the calves (210 days), the cows and calves were kept in individual pens. The nutritional requirements of the cows for maintenance and lactation were met. The same ration was offered to the calves from the 90 days of age, in limited amounts to supply 30% of the nutritional requirements. The ration was formulated with 30% of concentrate and 70% of silage, DM basis. Monthly, milk production of the cows was estimated, utilizing the weigh-suckle-weigh method. By means of nonlinear model, it was estimated the time needed for the cows to reach the peak of lactation, the production at the peak of lactation; the persistence of milk production and total and daily average milk production. Nellore cows showed lower production at the peak of lactation, total and daily average milk production, but higher persistency than crossbred cows. The productions in the lactation peak, total and daily average, in cows SN, were higher than in cows LN, however, no difference was observed between these groups for lactation persistence. Calves from Nellore cows had lower birth weight, weaning weight and preweaning weight gain than those from crossbred cows. There was no difference between calves from the two crossbred groups. It is concluded that crossbred cows have higher maternal ability than Nellore cows.

Ganho de peso, eficiência alimentar e características da carcaça de novilhos de origem leiteira

The objective of this work was to evaluate the weight gain, feed efficiency and carcass characteristics of dairy steers. Sixteen Holstein dairy steers with initial average age and weight of 20 months and 202,0 kg were used. The animals were divided into four groups. One group of animals was slaughtered at the beginning of the trial (AI) and three groups were ad libitum fed (AL-1, AL-2 and AL-3) and they were slaughtered when the individual weights of 250.0, 300.0 and 350.0 kg were reached, respectively. The diet contained 1:1 forage to concentrate ratio on dry matter basis with 12.48% of crude protein. Feed intake per kg of live weight gain increased as live weight increased, from 250.0 to 350.0 kg. There were no differences in live weight gain among the three groups AL-1, AL-2 e AL-3 (respectively, 1.26, 1.14, and 1.01 kg/day). There were also no differences among the three groups regarding to the proportion of muscle and fat tissues, and bones in the carcass. There was a tendency of decrease in the percentage of bones, as animal live weight increased. No differences were observed among the groups for carcass dressing and their primal cuts yield. Linear regression equations that allowed good estimates of empty body weight, in function of the live weight and of the carcass weight and in function of empty body weight, were obtained.

Uso do abate comparativo na determinação da exigência de energia de mantença de gado de corte pastejando capim-elefante: descrição da metodologia e dos resultados

The maintenance net energy requirement of steers grazing elephangrass (Pennisetum purpureum, Schum) cv. Napier, as unique food, was determined. The trial lasted 175 days. Nine 0.5 ha paddocks were implanted in flat-land, in rotational grazing, were used. Thirty-six ¾ Gyr-Holstein steers averaging initial age of 20 months and 332 ± 37 kg body weight (BW) were used. Half of animals had grazing time restricted to four hours daily, to limit energy intake at a level close to maintenance, and half had free access to pasture. Six steers were slaughtered at the beginning of trial to determine initial body composition (reference group), and six were slaughtered each 35 days. Body composition was determined by chemical analysis of representative samples of all animal body. The net energy maintenance requirements were estimated as heat production at zero level of metabolizable energy intake, regressing log heat production on metabolizable energy intake, per day and per unit metabolic size. Two equations were fitted: for the first, metabolic size was calculated as a function of body weight (BW0.75) and for the second as function of empty body weight (EBW0.75). Forage intake and digestibility of forage consumed (extrusa) were determined monthly. The grazing time restricted to four hours a day allowed intake of energy at level close to maintenance as indicated the individual weight gains, showing that the procedure used in this research might be used in future trials. The net energy maintenance requirement observed was 57 kcal/kg LW0.75 or 63,27 kcal/kg EBW0.75. The values obtained fall into the range of values observed in Brazil and were lower than those recommended abroad for European type cattle.

Avaliação nutricional da grama-estrela cv. Africana para vacas leiteiras em condições de pastejo

An nutritional analysis of stargrass cv. Africana fed dairy cattle under rotational grazing was evaluated in this research. Ten Holstein-Zebu crossbred cows were managed in 2 ha covered with the grass and divided in 11 paddocks /ha with three grazing days 30 days of resting period. During the experimental period the animals were milked twice a day for 16 days and were feed two kg of concentrate. Representative samples of the pasture consumed (extrusa) were taken and determined the nutritional composition. The dray matter intake of the animals was estimated by means of chromium and indigestible DM as external and internal markers. The individual performance of the cows was evaluated by daily milk production and by weighting the animals. The food matter dynamics was estimated with gravimetric in vitro techniques, cumulative gas production from microbial fermentation and estimates of the passage kinetics of solid end liquid phases. The amount of total net energy (NEt) in MJ/d meet the energetic requirement by the animals. The predicted values for metabolizable protein (MP) corresponded to the supply of 91% of the MP required by those animals. The predictions for macrominerais met only 75% of the Ca required, however met the requirements by other macrominerals. The stargrass pasture meet the nutritional requirements for maintenance and production of 11.7 kg of milk per day. In the studied circumstances, it is needs to supplement nutrients that complement MP e Ca not fully met. The content and kinetic characteristics of stargrass fiber caused niether rumen fill effect nor constrained int1ake of grazing dairy cows.

Conteúdo corporal e exigências líquidas de energia e proteína de novilhos mestiços Holandês-Gir em ganho compensatório

Thirty-three 39 crossbreed Holstein-Gyr steers were used in a research aiming to evaluate the effects of feed restriction prior to the confinement on the changes in body composition and in the net requirements of energy for maintenance and weight gain, and protein for weight gain. Thirty animals were submitted to a high grazing pressure, while the remaining nine steers had unrestricted access to forage (continuous gain group), after what, six animals from the first group and three from the second group were slaughtered, and the remaining animals were confined. From 24 animals of the compensatory growth group, 12 were fed ad libitum (compensatory growth group) and 12 were fed 15% above the maintenance level (maintenance group), while six animals from continuous gain group were fed the same ad libitum diet. The diet was constituted by corn silage and 26% of concentrate. The net energy requirement for maintenance was determined by regression of the heat production, in function of the metabolizable energy intake (ME), adjusting for heat production at zero level. Regression equations of the log of the body contents of fat, protein and energy in function of the log of the empty-body weight (EBW) were fitted. The average maintenance net energy requirements for the animals in the compensatory growth group was 47,50 kcal/kg0.75/day. The total fat and energy content in body-weight-gain increased as body live weight increased. The net requirements of energy and protein for 1 kg of EBW gain were 3.13 Mcal/day and 189.4 g/day, respectively, for a 300 kg live weight steer.