Reducing crude protein in diets on the metabolic balances for pigs kept in different thermal conditions

Abstract

The objective of this study was to evaluate the reduction of crude protein diets on nitrogen balance, urinary pH and blood parameters of starter pigs. The average initial weight of the animals was 18.5 ± 0.73 kg. Two digestibility experiments were conducted, one in environmental conditions of stress (28.77 ? C) and another in thermal comfort condition (18.13 ? C). In both experiments, the animals were distributed in randomized blocks with four decreasing levels of crude protein (20.5, 19.4, 18.3 and 17.2%) and four replications, totaling 16 experimental units in each experiment, each represented by an animal, totaling 32 animals. The methodology used was the total collection of feces and urine was collected and filtered daily. To assess blood parameters, samples were obtained by jugular vein puncture. The parameters evaluated were ingested nitrogen, excreted in feces and urine, absorbed, retained, retained/absorbed, total excretion, net protein utilization, urine pH, cholesterol, triglycerides, glucose, urea and creatinine in blood plasma. It is concluded that reducing the level of protein in the diet, 20.5 to 17.2%; is an efficient alternative to reduce the amount of nitrogen excreted by pigs in heat stress condition. In thermal comfort condition pigs showed higher concentration of creatinine and serum cholesterol.