Effects of increasing dietary arginine supply during the three first weeks after weaning on pig growth performance, plasma amino acid concentrations, and health status

Abstract

A total of 425 weaned pigs [Exp. 1: 225 pigs (5.8 ± 0.9 kg); Exp. 2: 200 pigs (6.1 ± 1.2 kg)] were used to determine the optimal dietary standardized ileal digestible (SID) arginine (Arg) level in early nursery diets based on growth and health responses. The basal diet in Exp.1 was formulated to meet SID Arg recommendation (0.66 % - NRC, 2012) and in Exp. 2 SID Arg was set to simulate current industry practices for feeding nursery pigs (1.15 %). Basal diets were supplemented with 0.3, 0.6, 0.9, and 1.2% of L-arginine to provide 5 levels of dietary SID Arg. Experimental diets were fed during phases 1 (d0-d7) and 2 (d8-d21) with common diets until market. Feed disappearance and body weight (BW) were measured at d7, 14, 21, and 43. Final BW was recorded at first removal of pigs for market. Pen fecal score was assigned daily from d0 to d21. Plasma immunoglobulin A (IgA) was determined at d0, 7, and 14 and amino acids (AA) concentration and plasma urea nitrogen (PUN) at d0 and 14. Orthogonal polynomial contrasts were used to determine the linear and quadratic effects of dietary Arg. Optimal SID Arg was determined by fitting the data with piecewise regression, using growth performance as the primary response variable. In Exp. 1, dietary Arg linearly increased (P<0.1) BW, average daily gain (ADG), and gain to feed ratio (G:F) ratio at d21, as well as reduced (χ2=0.004) the percentage of pigs that lost weight (PLW) in week 1 by 29%. Dietary Arg resulted in linear improvement (P=0.082) of ADG for the overall nursery period and quadratic improvement (P<0.1) of final BW at marketing. In Exp. 2, dietary Arg linearly increased (P<0.05) ADG and average daily feed intake (ADFI) in week 1, BW and ADFI (P<0.1) at d14, as well as reduced (χ2=<.001) PLW in week 1. From d0 to 21, G:F was improved quadratically (P<0.1). Dietary Arg linearly increased (P<0.1) ADG and BW at d43. Dietary Arg supplementation decreased incidence (χ2<0.05) of soft and watery feces during the first weeks after weaning and lower concentration of plasma IgA at d7 and 14. Dietary Arg linearly and/or quadratically influenced plasma AA concentrations (P<0.05), including an increase in Arg, Leu, Phe, Val, citrulline, ornithine, and PUN concentrations. Overall, weaned pigs exhibit optimal nursery growth performance and health when provided with dietary SID Arg ranging from 1.5% to 1.9%. This dietary range contributes to a reduction in the occurrence of fall-back pigs and improvements final BW at marketing.