The Benefit of L-Threonine Supplementation on Growth Performance, Carcass Characteristics, Intestinal Morphology and Litter Quality of Broilers.

ABSTRACT This study was carried out to investigate the effect of dietary L-Threonine supplementation on broiler performance, carcass characteristics, duodenal histo-morphology and litter analysis. It was hypothesised that the overall broiler performance would be improved in threonine adequate diets with reduced environmental impact when using L-threonine supplementation. A total of 144-sexed Ross 308 broiler chicks were randomly allocated into 3 dietary treatments. Each treatment was replicated 6 times with 8 birds per replicate (4 male and 4 female). Treatment group 1 served as threonine deficient group, fed with a diet with all limiting amino acids met except threonine as no synthetic form was supplied. Treatment group 2 served as threonine adequate high crude protein, where L-Threonine adequacy was achieved with higher level of crude protein. Treatment group 3 served as L-Threonine adequate but achieved it through L-Threonine supplementation. Treatment effects on growth performance, carcass characteristics, intestinal morphology and litter quality were determined. Results compared to group 1 showed that group 3 at the end of the experimental period (28 days) had improved final body weight P < 0.05, live and carcass weights P < 0.01, dressing yields P < 0.05, relative wing weights P < 0.01 and relative heart weights P < 0.05. However, group 2 showed numeric improvement in all aforementioned parameters but not enough to show significance. Litter moisture and nitrogen content was affected by dietary L-Threonine fortification P < 0.05. The lowest moisture and nitrogen content were noticed in group 3. Meanwhile, group 2 showed the highest nitrogen and group 1 showed the highest moisture content among all groups. Intestinal villi length and villus: crypt ratio was affected by dietary treatments P < 0.001 and P < 0.05 respectively. Group 3 showed the highest villus length and villus: crypt ratio followed by group 2 and group 1. In conclusion correcting L-Threonine deficient diet by adding L-Threonine significantly improved live weight gain and carcass characteristics, while numerically improved feed conversion ratio and breast weight. Correcting the deficit by supplying crude protein had no significant effect. Additionally, dietary L-Threonine supplementation reduced environmental burden by reducing both litter nitrogen and moisture content.