Growth performance, carcass quality, immune response, and production economics of broiler chickens fed avocado seed meal under feed restriction

Abstract

Feed restriction is effective in reducing feed costs, however it may have adverse effects on growth performance. Phytogenic feed additives has been explored for their potential to enhance digestion and support growth in poultry. Therefore, this study aimed to evaluate the effects of avocado seed meal on growth performance, carcass quality, immune response, haematological indices, and production economics of broiler chickens under feed restriction. One hundred and twenty 1-day-old Cobb 500 broiler chicks were assigned to a 2 × 2 factorial arrangement comprising two feeding regimens (ad libitum and 8-hour time-restricted feeding) and two avocado seed meal (ASM) levels (0 mg/kg and 3000 mg/ kg), resulting in four treatments with 12 replicates during 42-day feeding trial. Feed restriction significantly (P < 0.05) decreased final body weight (11.42%), weight gain (11.60%), feed intake (11.10%), slaughter weight (12.24%), and dressing percentage (3.13%) but increased relative organ weights (lung, liver, heart, spleen, gizzard, and pancreas) of the broiler chicken compared to unrestricted group. Supplementation of ASM had no significant effect (P > 0.05) on growth performance and carcass traits except for relative heart and pancreas weights of the broiler chickens. Economic analysis showed that feed-restricted broilers had lower feed costs (N3376.39) but reduced revenue (N6866.87) and income over feed costs (N3490.48) compared to the ad libitum group, while ASM inclusion did not significantly (P > 0.05) affect economic outcomes. Feed-restricted broilers exhibited lower red (2.68 × 1012/L)) and white blood cell counts (3.20 × 109/L), while ASM supplementation maintained normal haematological parameters. Immune responses showed elevated IgG (313.75mg/dL) and IgM (153.17mg/dL) levels in feed-restricted broilers, with ASM inclusion affecting IgM levels but not IgG concentrations. The influence of feed restriction × ASM supplementation interaction was not significant (P > 0.05) on final body weight, body weight gain, feed intake, cost of feed intake, revenue, and income over feed cost per bird across treatments. However, a feed restriction × ASM supplementation interaction occurred on feed conversion ratio, dressing percentage, liver, heart, gizzard, pancreas weights and IgM levels across treatments. The study concludes that supplementation of ASM at 3000 mg/kg could minimize the negative influence of feed restriction on growth performance, carcass traits, and economic returns during production.