Abstract
Assessment of the productive efficiency of 30 primiparous Aberdeen Angus cows of different body sizes, classified at calving as heavy (375±10.5 kg) or light (283±7.7 kg), and different total milk-yield levels, classified as high (868±24.5 kg) or low (547±18.3 kg). Heavy cows were superior in weight at calving and weaning, but there were no differences in milk yield and weight at birth and weaning of calves. Heavy cows were less efficient than light cows in the production of kilograms of calves per 100 kg of cows at calving and at weaning. High-producing cows were heavier at calving and had heavier calves at birth and weaning, but did not differ between the milk-yield levels for the variation in daily weight. The variation in daily weight of the calves was greater from high-producing cows. High-producing dairy beef cows were more efficient at weaning, and their calves required less milk to produce one kilogram of live weight.
Highlights
The intensification and competitiveness of beef cattle farming lead producers to seek moreefficient animals adapted to the productive systems, with greater production in less time and at lower costs, thereby providing better economic indices to the activity
The present study aimed to evaluate the productive performance from calving to weaning of primiparous Aberdeen Angus beef cows with two body sizes and two milk yields under extensive rearing conditions, as depending on body size and milk production of inhibitors of the production efficiency of the herds
The classification of groups according to cow weight determined differences in cow body weight at calving (P
Summary
The intensification and competitiveness of beef cattle farming lead producers to seek moreefficient animals adapted to the productive systems, with greater production in less time and at lower costs, thereby providing better economic indices to the activity. Productive systems usually associate better feeding conditions to the nutritional requirements of the categories. In extensive conditions in the subtropics used in southern Brazil the nutrient availability does not meet the requirements of animals, resulting in low productive indices, which impacts production. In the South of Brazil, approximately two cows are required to wean one calf per year (VAZ et al, 2010a). The best indicator for evaluating beef-cattle breeding herds under extensive conditions is the weaning rate (VAZ et al, 2010b). The weight of calves at weaning and the kilogram of calves per cow kept in the herd are efficient indicators for the evaluation and decision-making process of production systems
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