Effects of dietary fish silage and fish fat on growth performance and meat quality of broiler chicks
Two experiments were conducted to study the effect of concentrated fish silage and additional fish fat on growth performance (exp. 1) and meat quality (exp. 2) of broiler chicks. In exp.1, 600 day-old male and female chicks with an initial weight of 36.3 g ± 0.6 SD were allocated to five treatment groups. The treatments were a control diet, two test diets with 50 g kg−1 fish silage and different levels of fish fat (6 or 8 g kg−1), and two diets with 100 g kg−1 fish silage and different levels of fish fat (8 or 10 g kg−1). In exp. 2, 150 day-old female chicks with an initial weight of 36.3 g ± 0.7 SD were allocated to five treatment groups. The treatments were a control diet, and one of four test diets containing 50 g kg−1 fish silage and different levels of fish fat (2, 9, 17 or 25 g kg−1). In exp. 1, chicks fed diets with fish silage had a greater weight gain (P < 0.001), a greater feed intake (P < 0.05) and a lower feed-to-gain (MJ ME kg−1) (P < 0.001) than those fed the control diet. In exp. 2, no significant differences in weight gain or carcass weight were found among diets. The proportions of the fatty acids C18:3, C20:1, C20:5, C22:5 and C22:6 in abdominal fat, and C20:1, C22:1, C22:5 and C22:6 in breast meat, increased by the dietary inclusion of fish silage and fish fat. Increasing levels of dietary fish fat decreased blood plasma levels of vitamin E and ceruloplasmin. The diets containing the highest levels of fish fat (16.8 or 24.8 g kg−1) caused off-odour and off-taste of thigh meat stored at −16 °C for both six months and one month. Key words: Fish silage, fish fat, broilers, growth performance, sensory quality