Kepler Euclides Filho

Desempenho de novilhos F1s Angus-Nelore em pastagens de Brachiaria decumbens submetidos a diferentes regimes alimentares

O objetivo deste experimento foi avaliar as eficiencias biologica e economica de sistemas de alimentacao, durante os periodos criticos, como alternativa de reducao da idade de abate de bovinos recriados em pastagens de Brachiaria decumbens. Sessenta bezerros F1s Angus-Nelore desmamados foram distribuidos nos seguintes tratamentos: A) sem suplementacao; B) suplementacao somente no primeiro periodo seco; C) suplementacao apenas na segunda seca; D) suplementacao nos dois periodos secos; e E) suplementacao no primeiro periodo seco e confinamento no segundo. Os suplementos utilizados foram racoes comerciais fornecidas diariamente em quantidades equivalentes a 0,8 e 0,9% do peso vivo, nas primeira e segunda secas, respectivamente. O confinamento durou 100 dias e os novilhos receberam, ad libitum, uma racao contendo 40% de feno de Brachiaria decumbens e 60% de concentrado. O periodo experimental foi da desmama ate o abate (460 kg). Durante o primeiro periodo seco, os animais suplementados apresentaram maiores ganhos de peso diario (GPD) que os nao suplementados, 460 e 70 g, respectivamente. Durante o segundo periodo seco, os animais confinados apresentaram maiores GPD (1.285 g), seguidos dos suplementados em pasto (580 g), enquanto os nao suplementados perderam peso (-180 g). Houve aumento na capacidade de suporte dos pastos, onde os animais receberam suplementacao, em 24 e 30%, durante os primeiro e segundo periodos secos, respectivamente. Os animais que passaram por restricao alimentar no segundo periodo seco apresentaram ganho compensatorio, quando cessou a restricao, mas esse nao foi suficiente para que os animais atingissem pesos de abate a mesma idade dos suplementados. As idades de abate foram 30,1; 28,0; 26,6; 24,2; e 22,0 meses, respectivamente, para os tratamentos A, B, C, D e E. Tambem foi apresentada a avaliacao economica.

Tendência genética na raça Gir

The importance of weight and weight gain for beef cattle production is responsible for the great emphasis that is devoted to these traits by breeders of different breeds. However, it is very important to maintain the animal breeding programs under surveillance in order to evaluate the genetic progress obtained by a breed as a whole. Thus, this study had the objective of evaluating the genetic trends for gain up to weaning and for gain from weaning to yearling considering the direct genetic and maternal genetic effects for preweaning gain and genetic direct effect for postweaning gain. The genetic trends were estimated by the regression of the annual average expected progeny differences on birth year of the calf. Positive trends were observed for preweaning gain, genetic direct and maternal genetic effect as well. This tendency was also observed for genetic direct effect for postweaning gain. The regression coefficients were 0.19, 0.06 and 0.026 g day-1, for genetic direct and genetic maternal effects for preweaning gain, and for genetic direct effect for postweaning gain, respectively.

Eficiência Bionutricional de Animais da Raça Nelore e seus Mestiços com Caracu, Angus e Simental

The data utilized in this study were obtained from 23 intacted animals from three different genetic groups: seven Nellore (N), eight ½ Caracu + ¼ Angus + ¼ Nellore (CCAN) and eight ½ Caracu + ¼ Simental + ¼ Nellore (CCSN). These animals were produced as part of an ample project which is being carried out at Embrapa Gado de Corte whose main objective is to identify a genetic group that besides being adapted, is capable to produce meat of high quality in an efficient and competitive way (Indo-Euro composite project). This particular experiment had the objective of evaluating the bio-nutritional efficiency (EBN) of such animals. In order to do that, the variables weight gain and dry matter consumption were jointly analyzed under a bivariate model. Using the higher eigenvalue, it was established the first discriminant canonical function, which, in turn, was utilized for obtaining the EBN values. The statistical analysis revealed to exist a significant effect of genetic group on EBN. The EBN averages were compared by two different contrasts: C1) CCAN versus CCSN; and C2) average for CCAN and CCSN versus N. Since both contrasts were significant it was concluded that there is difference between the performance of the two crossbred groups and, that the CCAN animals presented better EBN than the CCSN ones (60.72 versus 48.63, respectively). The F1s animals, on the other side, presented better bio-nutritional efficiency than Nellore (54.67 versus 16,70). The least square means for daily dry matter consumption during the evaluation period as well as for average daily gain were, respectively, 6.47 kg and 1.00 kg, 7.90 kg and 1.23 kg, and 7.57 kg and 1.15 kg for N, CCAN and CCSN animals, respectively.

Efeito de idade à castração e de grupos genéticos sobre o desempenho em confinamento e características de carcaça

Seventy-one animals from two genetic groups, ½ Angus - ½ Nellore (AN) and ½ Simmental ¾ ½ Nellore (SN) with different growth potential, which belonged to the Projeto Cruzamento Embrapa 1 were used. These groups were submitted to seven castration treatments. It was observed that the SN animals delayed 14 more days in feedlot in order to be slaughtered in the same degree of finishing as the AN (131 days versus 117 days, respectively) animals. The other evaluated traits, slaughter weight, cold carcass weight, carcass dressing, longissimus muscle area, were not affected by genetic group. The averages for these traits in this same sequence were 471 kg and 476 kg, 266 kg and 274 kg, 58.13% and 57.46% and 72.71 cm2 and 75.79 cm2 for AN and SN animals, respectively. The comparisons among treatment means were carried out through six different contrasts. It was observed that young bulls delayed under feedlot confinement 25 more days than those castrated at birth (136 days versus 111 days, respectively). However, these animals showed heavier slaughter weight than those castrated at birth (515 kg versus 463 kg, respectively). Animals castrated at birth stayed longer in feedlot than those castrated at weaning or castrated as yearling (111 days versus 95 days, respectively). Animals feedlot confined just after weaning, as it should be expected, were those that delayed longer under feedlot confinement (181 days). Since these animals were one year younger than the other animals, the longer time required for them to attain the end point did not result in heavier slaughter weights (455 kg). The average carcass dressing independent on genetic group and treatment was 57.79%.

Eficiência bionutricional de animais Nelore e seus mestiços com Simental e Aberdeen Angus, em duas dietas

This experiment was carried out for two years with the objective of evaluating the performance of genetic groups with different genetic potentials for growth, such as Nellore (N), ½ Angus - ½ Nellore (AN) and ½ Simmental - ½ Nellore (SN).This study is part of an ample project, which has as principal goal, to evaluate the efficiency of production of systems composed by animals with different mature sizes (Projeto cruzamento Embrapa 1). Using a bivariate analysis involving the variables average daily gain and dry matter intake, it was determined the first discriminant canonical function which was used for estimating performance indexes that were denominated bio-nutritional efficiency. The data were obtained from 72 animals under two diets, one composed by Tanzânia hay plus 600 g of ground soybean (diet A), provided ad libitum, and other where this hay was combined with a concentrate ration (diet B). The bio-nutritional efficiency was significantly affected by the interaction between genetic group (GG) and diet (D). Thus, the least square means were compared by four different contrasts. These contrasts were, on diet B: C1) Nellore versus average of crossbreds and, C2) ½ Angus - ½ Nellore versus ½ Simmental - ½ Nellore. And on diet A: C3) Nellore versus crossbreds and, C4) ½ Angus - ½ Nellore versus ½ Simmental - ½ Nellore. The analyses of these contrasts revealed that, independently on diet, Nellore animals had a worst performance than the average observed for the F1s. The average of bio-nutritional efficiencies were equal to 429.74 and 490.46 for Nellore and crossbred animals, respectively, on diet B and, in the same sequence, 299.70 and 376.10 on diet A. Relatively to the F1 animals, their performances were dependent on diet. On diet A, the ½ Angus - ½ Nellore and ½ Simmental - ½ Nellore presented the same bio-nutritional efficiency (376.10) while on diet B, the ½ Angus - ½ Nellore were superiors (529.84 versus 451.09).

Avaliação das carcaças de novilhos F1 Angus-Nelore em pastagens de Brachiaria decumbens submetidos a diferentes regimes alimentares

This trial was conducted at National Beef Cattle Research Center of Brazilian Agricultural Research Corporation (Embrapa Beef Cattle). Forty five F1 Aberdeen Angus-Nellore steers were used to evaluate the effects of different dry seasons feeding schemes on carcass characteristics. The treatments were: control, without supplementation (S/S); supplementation in 2nd dry period (S2S); supplementation in 1st dry period (S1S); supplementation in 1st and 2nd dry periods (S12S) and supplementation in 1st dry period and confinament in 2nd one (S1C2). Animals were slaughtered at 460-480 kg of live weight and the treatments effects were evaluated by least square means. Steers with higher nutritional levels in 2nd dry season (S1C2; S2S; S12S) showed more dressing percentage and higher hot and cold carcass weights than those supplemented only in 1st dry period or non supplemented. Animals supplemented only in 1st dry season showed similar carcasses than non supplemented. It was concluded that increasing the 2nd dry season nutritional level is primary to expand the dressing percentage. Supplementation in 1st dry period solitarily does not affect dressing percentage neither carcass quality.

Efeitos genéticos aditivos direto e materno sobre o peso à desmama em animais mestiços Europeu-Zebu

The data used in this study are results of the evaluations of crosses among European breeds and Nellore breed. The data regarding to the weaning weight of 883 calves resulted from six mating groups involving crosses of Simental, Charolais and Chianina breeds with Nellore, backcrosses and pure Nellore, were used. The weaning weights were adjusted for cow and calf ages and contemporary group (formed by the combination of year and season of birth and sex) to estimate direct and maternal genetic additive effects on weaning weight. These effects were estimated by regression of the weaning weight on the individual breed composition, which was considered as a proportion of Nellore genotype. The direct additive effect estimates were 4.43 kg for Simental breed, 6.58 kg for Chianina breed and 15.24 kg for Charolais breed. The maternal additive effect estimates, however, were 41.78 kg for the Simental breed, 26.50 kg for the Charolais breed and 26.11 kg for the Chianina breed.

FATORES DO AMBIENTE SOBRE O PESO AO DESMAME DE BEZERROS DA RAÇA NELORE EM REGIÕES TROPICAIS BRASILEIRAS

This paper had the objective of studying the influence of non genetic effects on the weaning weight of 105,465 calves of the Nellore cattle breed, born in eight different Brazilian regions, in the period of 1978 to 1994. The statistical analysis was accomplished using the least squares method, GLM procedure (SAS, 1996), with a model that included the fixed effects of sex, month and year of birth of the calf, region, farm within region and the covariable age of dam. All sources of variation included in the model were significant (P<0.0001). The importance of these non genetic effects on body weight of calf at 205 days of age indicates the need to consider them when estimating genetic parameters and breeding values for selection purpose.

Disseminação do melhoramento genético em bovinos de corte

With respect to beef cattle breeding, the emphasis devoted by researchers, beef cattle producers and beef cattle experts has been, in general, focused on identification, evaluation and selection of sires. Little attention has been given to the pathway used to spread the genes from such sires throughout the population as a whole. The reported low annual genetic progress observed in several herds might suggest that, in spite of having some success in promoting genetic improvement as observed in isolated herds, such dissemination occurs in a disorganized manner. Such procedure might explain the observed situation where the progress accomplished by some herds is masked by the negative genetic trends observed in others. The theoretical basis of genetic dissemination in beef cattle is reviewed and some theoretical models involving the pyramidal structure of beef cattle production are analyzed, as well as the calculations of the genetic lags involved in each situation.

Efficiency of calf production of cows from two genetic groups

The objective was to evaluate the effect of weight, age and production efficiency of cows from genetic groups based on the calf weight at calving and at weaning. For a period of five years, data of 120 cows (60 Angus-Nellore (AN) and 60 Simmental-Nellore (SN)) at four to nine-years of age were evaluated. All cows were maintained on Brachiaria decumbens pastures, with two forage availability levels (high and low), distributed in a randomized-block design. The cows were placed together with Canchim bulls to generate the crossbred calves. A supplement, consisting of 200 g/kg crude protein and 820 g/kg of total digestible nutrients, was provided to the calves in creep feeding until 210 days-old (weaning). Supplement had a significant effect on the weight of the cow at calving and weaning. The average weights of the Angus-Nellore cows were 529.19 and 514.23 kg at calving and on the weaning day, respectively. These values were higher for Simmental-Nellore cows, which presented 569.60 and 542.59 kg, respectively. The male-calf weight at weaning was 254.69 kg, which was higher than the females (237.70 kg). Genetic group had no effect on weaning weight. The average weight for Canchim × Angus-Nellore calves was 243.41 kg and for Canchim × Simmental-Nellore it was 248.98 kg. Cow age affected weaning weight, promoting a linear increase of 0.804 kg in the weaning weight each year. Younger and smaller cows (Angus-Nellore) are more efficient for calf production.