PSVII-6 Precision feeding and reduced crude protein on nitrogen efficiency of pigs raised under tropical conditions

Abstract

Feeding pigs with low protein diets is suggested to attenuate the negative effects of heat stress in pigs reared in hot climate areas, without changes on pigs performance. This study aimed to evaluate the nitrogen balance of pigs raised under tropical conditions and fed in conventional group-phase feeding systems (CON) or fed individually with daily tailored diets (IPF) receiving diets formulated with low (LCP) or high (HCP) crude protein. Sixty male castrated pigs (39kg±0.98) were assigned to 4 treatments in a 2×2 factorial arrangement. The experiment lasted 56 days (phase 1: d 0–28, and 2: d 29–56). CON fed pigs received within each phase a constant blend of diets A (high nutrient) and B (low nutrient density) supplying the estimated nutrient requirements of the group, whereas IPF pigs received daily a personalized blend providing the estimated amount of nutrients. Body lean was assessed by a dual-energy X-ray absorptiometry at the beginning and at the end of each phase and converted to body protein. Data were analyzed using the MIXED procedure of SAS including the fixed effects of feeding system, feed formulation, and their interactions. Pigs receiving LCP diets reduced the CP intake in 27% (P < 0.001). However, IPF pigs consumed on average 15% less CP than CON pigs (P < 0.001). Regardless of the reduced CP intake, LCP fed pigs showed a greater N retention than pigs receiving HCP diets during the first phase (P < 0.01). Moreover, pigs fed LCP diets excreted 30% less N to the environment than pigs fed HCP diets (P < 0.001). When LCP diets are complemented with the use of IPF technique, the N excreted can be reduced 18% more than in CON system (P < 0.001). Our results indicate that LCP diets and IPF are feasible to improve the nitrogen utilization of pigs raised under tropical conditions.