Effects of dietary threonine and tryptophan supplementation on growing pigs induced by porcine respiratory and reproductive syndrome vaccination

A total of 32 growing pigs were used in a 2 × 2 factorial arrangement of treatments with two different diets (conventional [CON] diet vs. threonine [Thr]- and tryptophan [Trp]-rich [TTR] diet) and two immunological challenge regimens (porcine respiratory and reproductive syndrome [PRRS] vaccine vs. phosphate buffer solution [PBS]) to study the hypothesis that dietary supplementation with Trp and Thr would benefit for growing pigs vaccinated with PRRS vaccine. After feeding the experimental diets for 21 d, the pigs were intramuscularly vaccinated with PRRS or PBS. Performance data were recorded over a period of 10 weeks and are presented for the pre-challenge period (3 weeks) and the challenge period (7 weeks, where on day 1, pigs were immunologically challenged). During the pre-challenge period, the growth performance was not different between dietary treatments. PRRS vaccination resulted in increased rectal temperature and decreased feed intake and growth rate (p