The effect of feeding different levels of sardine fish silage on broiler performance, meat quality and sensory characteristics under closed and open-sided housing systems

Two experiments were conducted to evaluate the use of fish silage prepared from Indian oil sardines, Sardinella longiceps, as partial replacement of soybean meal as a sole source of protein for growing broiler chickens. The main objective of Experiment 1, an ileal digestibility assay, was to assess the nutritional value of fish silage compared with soybean meal for feeding broiler chickens. The two test ingredients, soybean meal and dried fish silage, were incorporated into semi-synthetic diets, as the only component containing protein. The ileal digestibility coefficients of amino acids of fish silage were considerably higher than those of soybean meal (p<0.001). The lower digestibility of amino acids from soybean meal was related to the presence of anti-nutritional factors such as trypsin inhibitors. Fish silage had higher levels of sulphur-containing amino acids than soybean meal. The objective of Experiment 2, a growth study, was to evaluate the effect of feeding fish silage on performance and meat quality characteristics of broiler chickens raised under closed and open-sided housing systems. Four diets containing various levels of fish silage (0, 10, 20 and 30%) were evaluated. Daily feed intake, body weight gain and feed conversion ratio were measured. At the end of Experiment 2, 96 birds were randomly selected and slaughtered to evaluate meat quality characteristics. Housing type had significant effects on feed intake and body weight gain (p<0.01). Birds in the open-sided house consumed 4.7% less amount of feed and gained 10.6% less than their counterparts in a closed house. Birds in both houses fed diets containing 10 and 20% fish silage gained more than birds fed 30% fish silage. The current study produced evidence that fish silage can replace up to 20% of soybean meal in broiler diets without affecting either growth performance or the sensory quality of broiler meat.