Effect of Dietary Crude Protein Reduction in Weaning Pigs

Abstract

This experiment was conducted to evaluate the effect of dietary crude protein reduction on growth performance, blood profiles, and nutrient digestibility in weaning pigs. A total of 128 crossbred piglets ([Yorkshire × Landrace] × Duroc), weaned at 21 ± 3 d of age with average initial body weight of 7.68 ± 0.2 kg were used in this experiment during 5 weeks. Weaning pigs were assigned to one of 4 treatments in a randomized complete block (RCB) design in 8 replicates with 4 pigs per pen. Control diet had same level of dietary crude protein as NRC (1998) recommended, and 2% of dietary crude protein was reduced from 2% to 6% less then NRC recommendation. Three phase feeding programs were used in this experiment (phase I, d 0 to 7

phase II, d 7 to 21

phase III, d 21 to 35). In growth performance, reduction of dietary crude protein resulted in decrease of growth performance, but 2% reduction of dietary crude protein treatment showed significantly same rows with control diet (P<0.05). Pigs fed control diet showed the highest serum blood urea nitrogen (BUN) concentration, but insulin-like growth factor-1 (IGF-1) level was decreased by dietary crude protein reduction (linear, P<0.05). Sixteen crossbred barrows (4 pigs per treatment) averaging 16.28 ± 1.82 kg body weight were alloted in apparent nutrient digestibility. Dry matter digestibility was increased by dietary crude protein reduction (linear, P<0.05

quadratic P<0.01), and 4% reduction of dietary crude protein treatment showed significantly higher dry matter digestibility than other treatment (P<0.01). Four percent reduction of dietary crude protein treatment showed significantly power total nitrogen excretion than other treatment (P<0.01). Also, dietary crude protein digestibility was lowered by dietary crude protein digestibility (linear, P<0.05), and crude ash digestibility was increased by dietary crude protein reduction (linear, P<0.05

quadratic, P<0.05). Crude fat digestibility showed some tendency of increased than decreased, and 4% reduction of dietary crude protein treatment showed the highest crude fat digestibility (quadratic, P=0.08). In nitrogen retention, fecal nitrogen was decreased by dietary crude protein reduction (linear, P<0.05), and also, urinal nitrogen showed decreased tendency by dietary crude protein reduction (P=0.067). Consequently, reduction of dietary crude protein level in weaning pig diet reduce growth performance, but improve nutrient digestibility. And 4% dietary crude protein reduction could be acceptable for commercial weaning pigs feed with considering impact of environmental pollution.