Additional Valine and Isoleucine Impact Growth Performance, Intestinal Health, and Muscle Growth in Broilers Under Necrotic Enteritis Challenges

The current study aims to investigate the effects of additional valine and isoleucine in different necrotic enteritis (NE) challenge intensities. A total of 648 seven-day-old male Cobb 500 were allotted to nine treatments with six replicates. Two different NE intensity experiments (Exp-1 and Exp-2) were conducted. The five treatments for each NE experiment were as follows: (1) non-challenged shared control (NC), (2) NE challenge (NE), (3) 130% additional valine (VAL), (4) 130% additional isoleucine (ILE), and (5) 130% valine and isoleucine (MIX). In both experiments, all NE-challenged groups had decreased body weight gain compared to the NC group (<i>p</i> < 0.05). The ILE group in Exp-1 had further reduced body weight compared to the NE group on day 21 (<i>p</i> < 0.05). No significant differences were observed in intestinal permeability, jejunal NE lesion score, jejunal <i>C. perfringens</i> colony counts, jejunal morphology, jejunal gene expression levels, breast muscle yield, and body mineral compositions among all NE-challenged groups (<i>p</i> > 0.05). In conclusion, 130% additional valine and isoleucine hardly mitigated the negative effects of NE. Additional isoleucine may further worsen chicken growth performance, but this effect may vary depending on the intensity of the NE challenge.