Data from Hereford and Nelore breeds and their crosses were used to estimate the effect of genotype and environment interaction on weaning and yearling weights. The statistical analyses were performed by the least-squares method using models that included region, contemporary group within region, month of birth and sex of the calf, linear and quadratic effects of age of the calf and age of the cow, both nested within sex, and the genetic group and genetic group × region interaction effects. […]

The purpose of this study was to compare estimates of genetic effects obtained using the additive-dominance model and another which included parameters for joint-additive (complementarity) and epistatic effects, as well as evaluate alternative objective criteria for choosing the lambda coefficient in ridge regression implementation. The results indicated that the criterion to be employed at the choice of lambda not only depends on the data set and the model used, but also on a previous knowledge about the phenomenon under study […]

Reproduction efficiency of Holstein x Gir crossbred animals in Brazilian dairy farms were evaluated using data provided by the Brazilian Association of Girolando. A total of 2,600 records of age at first calving (IPP) and 3,763 records of calving intervals (IDP) were analyzed using the SAS® GLM procedure. Estimates of genetics effects: additive difference between Holstein and Gir breeds, dominance and additive x additive epistatic effects were obtained by regression models including genetic groups to model the performance of crossbred […]

The objective of this study was to evaluate body condition, weight, weight gain, food intake and efficiency of feedlot finished steers, purebreds (Charolais – C and Nellore – N), crossbreds from second (G2) (¾C ¼N and ¾N ¼C), third (G3) (5/8C 3/8N and 5/8N 3/8C) and fourth (G4) (11/16C 5/16N and 11/16N 5/16C) generations of rotational crossbreeding. The steers were fed the same diet containing 12.32% crude protein, 2.96 Mcal digestible energy/kg of dry matter and roughage:concentrate ratio of 52: […]

The objective of this work was to evaluate the carcass physical composition and meat quality of steers, straightbreds (Charolais – C and Nellore – N), and crossbreds from second (G2) (¾C ¼N and ¾N ¼C), third (G3) (5/8C 3/8N and 5/8N 3/8C) and fourth (G4) (11/16C 5/16N and 11/16N 5/16C) generation of rotational crossbreeding, feedlot finished with 52% corn silage plus 48% of concentrate in the diet. Crossbred steers were superior to the straightbreds mean for absolute weight of muscle, […]

The objective of this work was to evaluate the carcass characteristics of feedlot finished steers, straightbreds (Charolais – C and Nellore – N), and crossbreds from second (G2) (¾C ¼N and ¾N ¼C), third (G3) (5/8C 3/8N and 5/8N 3/8C) and fourth (G4) (11/16C 5/16N and 11/16N 5/16C) generations of rotational crossbreeding. Crossbreds showed higher slaughter, hot and cold carcass weights than the average of the purebreds, being the total heterosis, respectively, 14.95; 18.72 and 18.39% in G2, 19.98; 24.16 […]

The data analyzed were live weights of females (3475) of six genetic groups obtained by crossing red and white Holstein-Friesian (HVB) x Guzerá (Guz), with expected HVB gene fractions 1/4, ½ (F1) , 5/8 (from inter se mating), 3/4, 7/8 and > 31/32. The data were separately analyzed for 374 calves (up to age 120 d) and 524 heifers (121 to 550-d-old), using Proc Mixed of the SAS package, under a model including the fixed effects of genetic group (G), […]

The objective of the experiment was to evaluate the biologic efficiency of Charolais (CH) and Nellore (NE) cows nursing CH and ½NE ½CH (produced by CH cows), NE and ½CH ½NE (produced by NE cows) calves, mantained together until weaning, on native pasture (NP) or winter (oat + italian rye grass) and summer (alexander grass) cultivated pasture (CP). Cows and calves were weighted at birth; 14; 42; 70; 98; 126; 154; 182 days; and at weaning. The cows milk yield […]

Monthly weights (18.089) of 412 females on a demonstration farm in the Zona da Mata, Minas Gerais State, were used to develop a model to describe the liveweight of cows, heifers and calves. The data were analyzed using Proc Mixed of the SAS package, separately for the following categories: a) cows, b) heifers older than 12 mo., c) heifers 70-d to 12 mo-old and d) female calves up to 70 d. For each of these, the regression equations of weight […]

The objective of the experiment was to evaluate the performance of Charolais (CH) and ½Nellore (NE) ½CH (produced by CH cows), NE and ½CH ½NE (produced by NE cows) calves, mantained with the cows until weaning, on native pasture (NP) or winter (oat + italian rye grass) and summer (alexander grass) cultivated pasture (CP). Sixty straigthbred or crossbreds calves were used, and weighted at birth; 14; 42; 70; 98; 126; 154; 182 days; and at weaning. The cows milk yield […]