Atlantic salmon (Salmo salar) protein hydrolysate - Effect on growth performance and intestinal morphometry in broiler chickens

An experiment was conducted to evaluate the effect of two salmon protein hydrolysates on growth performance and intestinal morphometry in broiler chickens. Two different Atlantic salmon protein hydrolysates (SPH) from viscera were produced, one without the addition of exogenous enzymes and the other with added papain+bromelain during hydrolysis. The hydrolysates were included at 5% and 10% in both the starter and grower diets for broiler chickens. Additionally, one fish meal diet (FM) and a plant protein-based (PP) diet were included as controls in each period. Immediately after hatching, 5282 Ross308 broiler chickens were allotted to 66 pens and fed the starter diet from days 0-9 and the grower diet from days 10-28. Growth performance data were recorded for the starter period, early grower period (days 10-20) and late grower period (days 21-28), and duodenum, jejunum and ileum were sampled at day 10 for morphometric analysis. Inclusion of 10% SPH in the diet increased average daily gain (ADG) (P<0.05) compared with the broiler chickens fed the PP, FM and 5% SPH diets. Using contrast statistical analysis, the gain to feed ratio (G:F) was significantly higher in the groups fed the 10% SPH diets compared with the groups fed the PP and FM diets in the starter period. Also, ADG values were higher for the 5% SPH diet groups compared with the groups fed the FM (FM vs. 5% SPH, P<0.001) and PP (PP vs. 5% SPH, P=0.015) diets in the starter period. In the grower period, the impact of SPH inclusion on ADG diminished compared with the FM diet group; however, broiler chickens fed the PP diet did not reach the same final live-weight as broiler chickens fed the marine protein diets. There was a tendency towards longer villi in the duodenum and ileum, as well as larger villi absorption area in the ileum, of broiler chickens fed marine proteins compared with those fed the PP diet. No adverse effect on mortality or litter quality was detected when salmon protein hydrolysates were included in the broiler chicken diet. In conclusion, addition of salmon protein hydrolysates to broiler chicken starter diets improved growth performance compared with the PP and FM diets. Additionally, starter diets with inclusion of marine proteins tended to improve the small intestinal development in broiler chickens compared to a plant protein-based diet.