Abstract
The effects of supplementation with different protein: carbohydrate ratios on body composition, carcass characteristics and protein and energy deposition efficiency of young were assessed. Twenty-four Nellorecalves (132.5 ± 5.5 kgand 90-150 days of age) were kept on pasture for a 430 day experimental period. The treatments were: Control = mineral mixture only; HPHC = high-protein and high-carbohydrate supplement; HPLC = high-protein and low-carbohydrate supplement; LPHC = low-protein and high-carbohydrate supplement; LPLC = low-protein and low-carbohydrate supplement. Four animals at begning and 20 animal at end of experiment were slaughtered to evaluate the carcass composition. Control bulls had the lowest (p 0.05) between supplemented bulls (13 Mcal day -1 ). Although non-supplemented bulls had less (p 0.05) between supplemented bulls. High-carbohydrate supplements were associated with more (p 0.05) in the energy efficiency between the groups. Therefore, supplementation increases the intake and retention of protein and energy without changing the retention efficiency.
Highlights
The efficiency of feed utilization by cattle has been a concern of animal nutritionists and producers for centuries due to its obvious economic and environmental impacts
Animal Sciences protein and energy supply on feed utilization have been of interest during the last decades, our knowledge of the response and the efficiencies of feed utilization is relatively poor (SCHROEDER; TITGEMEYER, 2008), mainly with respect to grazing conditions
V. 36, n. 2, p. 215-224, Apr.-June, 2014 amounts of N being excreted into the environment (SCHROEDER; TITGEMEYER, 2008)
Summary
The efficiency of feed utilization by cattle has been a concern of animal nutritionists and producers for centuries due to its obvious economic and environmental impacts. The efficiency of feed use can be decreased by a lack, excess or unbalance of energy and nutrients in the feed. Animal Sciences protein and energy supply on feed utilization have been of interest during the last decades, our knowledge of the response and the efficiencies of feed utilization is relatively poor (SCHROEDER; TITGEMEYER, 2008), mainly with respect to grazing conditions. The efficiency of N utilization by ruminants is usually low, leading to high feeding costs and to large. Ruminants have low efficiency of use of nutrients, and cattle normally retain only 10 to 20% of nutrient intake (COLE et al, 2006). Many factors may affect the energy and protein efficiency of tissue deposition in an animal body
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