145 Performance, postweaning diarrhea, and apparent total tract nutrient digestibility responses of weanling pigs to nucleotide supplementation of low-protein diets

Abstract

Abstract Feeding low protein (LP) diets to nursery pigs has been reported to improve intestinal health, reduce incidence of post-weaning diarrhea (PWD) and nitrogen excretion. However, these benefits are often undermined by significant reduction in growth performance. This study evaluated the effects of low protein diets supplemented with dietary nucleotides on growth performance, post weaning diarrhea and nitrogen utilization. A total of 210 piglets (Duroc × Landrace × Yorkshire) were weaned at 21 d of age and allowed a 3-d adaptation to a common solid post weaning diet. At 24 d old, pigs were reweighed (6.02 ± 0.05 kg) and allocated to 5 dietary treatments in a completely randomized block design to give 7 replicates per treatment (n = 6 piglets per replicate). The 5 dietary treatments included i) a high protein positive control diet (PC) with 24% crude protein (CP); ii) a low protein negative control (NC) with 16% CP; iii) NC with 0.1% dietary nucleotide inclusion (NC01); iv) NC with 0.3% dietary nucleotide inclusion (NC03); and v) NC with 0.9% dietary nucleotide inclusion (NC09). All diets were corn-soybean meal based, supplemented with lysine, methionine, tryptophan, and threonine, with all low protein diets (LP) additionally fortified with crystalline isoleucine, and valine to meet the ideal amino acid requirements. Diets were provided ad libitum for 35 d and weekly feed intake (FI) and body weight (BW) were measured. On d 35, blood and fecal samples were collected to determine serum metabolites and nutrient digestibility respectively. Data were analyzed by PROC GLM and orthogonal polynomial contrast of SAS. Comparison between positive and negative control diets and nucleotide levels were performed with orthogonal contrast analysis. Relative to PC, NC diet had decreased overall average daily gain (343.5 vs. 305.5 g/d), incidence of PWD (2.5 vs. 1.2 fecal consistency score), blood urea nitrogen (BUN; 11.3 vs. 3.4 mg/dL) and total tract digestibility of energy (81.3 vs. 80.1 %; P < 0.05, P < 0.05, P < 0.0001 and P < 0.1, respectively). Relative to PC, the NC01, NC03 and NC09 treatments had comparable average daily gain (P > 0.05) while maintaining reduced (P < 0.05) BUN and incidence of PWD. Total tract digestibility of dry matter (83.1 vs. 82.1%) and energy (81.3 vs. 80.1%) were similar between PC and NC09 treatments (P > 0.05). Crude protein reduction decreased serum glutathione (P < 0.05), but without an effect of nucleotide supplementation. Serum glucose and insulin concentrations were not different across treatments (P > 0.05). Results suggest that feeding LP diets supplemented with dietary nucleotide after weaning can increase protein utilization efficiency, reduce incidence of PWD while partially ameliorating the negative effects of LP diets on growth performance.