Spray-dried plasma titration effects on growth performance, intestinal morphology, and immune system indicators of weaned pigs housed in a sanitation-challenged environment

Abstract

An experiment was conducted to test the hypothesis that increasing inclusion of spray-dried plasma (SDP) in diets improves growth performance and intestinal morphology and reduces inflammation in newly weaned pigs. Four-hundred weaned pigs (body weight: 6.05 ± 0.80 kg) were allotted to a randomized complete block design with 5 diets and 2 blocks (16 pens/diet; 5 pigs/pen). Pigs were placed in pens that were not cleaned to create a sanitation challenge. Phase 1 diets containing 0, 20, 40, 60, or 80 g/kg SDP were formulated. One pig per pen was sacrificed on d 14 and samples of intestinal tissue and mucosa were collected. During phase 1, growth performance parameters and body weight of pigs on day 14 increased (linear, P < 0.05) with increasing dietary SDP. Villus width in the jejunum of pigs on day 14 tended to increase (linear, P < 0.10) with increasing inclusion of SDP, and villus height to crypt depth ratio tended to be the greatest (quadratic, P < 0.10) for pigs fed a diet with 80 g/kg SDP. The jejunal mucosa concentration of interleukin- (IL-) 2 tended to be least (quadratic, P < 0.10) at 80 g/kg inclusion of SDP and IL-8 tended to increase (linear, P < 0.10) as SDP inclusion increased in the diet. Secretory immunoglobulin A in the ileal mucosa was greatest at 20 g/kg inclusion of SDP to the diet and then decreased with increasing dietary SDP (quadratic, P < 0.05), and IL-10 tended to be least at 40 and 60 g/kg dietary SDP, but increased with 80 g/kg dietary SDP (quadratic, P < 0.10). Activated T cells and the ratio of activated to regulatory T cells tended to be greatest at 40 g/kg dietary SDP but then decreased as SDP increased in the diet (quadratic, P < 0.10), whereas systemic lymphocytes linearly decreased (P < 0.05) as SDP increased in the diet. The concentration of plasma urea N also linearly decreased (P < 0.05) as dietary SDP increased, indicating greater amino acid utilization with greater dietary SDP. In conclusion, the optimal inclusion of SDP in diets for weanling pigs was at least 80 g/kg as indicated by improvements in growth performance and utilization of amino acids, but data for intestinal morphology and mucosal and systemic inflammation did not result in a conclusive optimum concentration of dietary SDP.