Nutritional evaluation of fish protein hydrolysate and its application in piglet production

This study was conducted to determine the digestible energy (DE), metabolizable energy (ME), and ileal digestibility of amino acids (AA) of fish protein hydrolysate (FPH), and to evaluate the effects of FPH on the performance of piglets. In Exp. 1, the available energy content of FPH was determined by difference methods: 12 barrows with an initial body weight (BW) of 40.0 ± 2.1 kg were randomly assigned into two dietary treatments with six replicates per treatment, the treatments contained a corn basal diet and an experimental diet in which 20% corn was replaced by FPH. The experiment lasted for 12 d, with 7 d adaptation period followed by 5 d total collection of feces and urine. In Exp. 2, the standardized ileal digestibility (SID) of AA in FPH by the N-free method was determined, 12 barrows (initial BW of 35.3 ± 1.8 kg) with ileal T-cannulas were randomly allotted into two treatments with six replicates per treatment, and the dietary treatments consisted of an experimental diet and a N-free diet. The experiment was lasted for 7 d, with 5 d adaptation period followed by 2 d collection of ileal digesta. In Exp. 3, the effect of FPH on the performance of piglets was conducted. One hundred ninety-two piglets (initial BW of 8.10 ± 1.8 kg) were randomly allotted into four treatments with six replicates per treatment. The treatments were a control diet with fish meal (FM) and part or all FM was replaced by FPH, receiving diets containing 2%, 3%, or 5% FPH. The experiment lasted for 28 d. Results showed that in Exp. 1, the DE and ME of FPH were 21.12 and 20.28 MJ/kg. In Exp. 2, the SID of Lys, Met, Thr, and Trp was 79.99%, 87.17%, 68.29%, and 71.53%, respectively. In Exp. 3, addition of 3% FPH increased nutrient digestibility and volatile fatty acid content in feces. Addition of 5% FPH increased the average daily feed intake (ADFI), significantly increased (P < 0.05) the activities of total antioxidant capacity (T-AOC), superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), and immunoglobulin A (IgA), while significantly decreased (P<0.05) the average daily gain (ADG). In conclusion, FPH had a high value of digestible energy and ileal digestible essential amino acids, and could improve nutrient digestibility, immunity, antioxidant capacity, and intestinal health of piglets, while adverse to nitrogen deposition in piglets.