Performance, digestibility efficiencies, gut and liver morphologies of snub nose pompano Trachinotus blochii fed spray‐dried haemoglobin meal as protein substitute for fishmeal

Abstract

Spray-dried haemoglobin meal, a by-product and derivative of the swine processing industry, is formed when haemoglobin is separated hygienically from pig's blood. A 120-days feeding trial using snub nose pompano Trachinotus blochii (1.01 ± 0.02 g) tested spray-dried haemoglobin meal (SHM) as an ingredient in six iso-nitrogenous (crude protein of 50%) and iso-lipidic (crude fat of 8%) diets, namely, a diet with 0% SHM (control) and five diets replacing fishmeal with SHM at 4, 8, 12, 16 and 20%. Weight gain percentage (WG%) significantly decreased (p < 0.05) when fish were fed diets with 12, 16 and 20% SHM inclusion levels. Feed conversion ratio and survival significantly decreased (p < 0.05) when fish were fed diets with 16 and 20% SHM inclusion levels. However, visceral somatic index, hepatosomatic index, condition factor and proximate composition were not affected (p > 0.05) by SHM inclusion levels. As an ingredient for pompano feed, SHM has digestibilities for protein, lipid and dry matter at 89, 78 and 45% respectively. No apparent pathological changes were observed in the intestines. However, physiological changes in the liver have been seen in fish fed diets containing 12, 16 and 20% of SHM. Based on the quadratic regression model at the maximum response of weight gain percentage, the optimum inclusion level of SHM was estimated to be 3.08% (5.87% SHM protein in the diet).