Use of Pacific thread herring ( Opisthonema libertate ) protein hydrolysates in Nile tilapia ( Oreochromis niloticus ) feeds: Productive performance and antioxidant enzymes on organisms exposed to a heat‐induced stress

The Nile tilapia (Oreochromis niloticus) industry represent the 71% of aquaculture total world production and demands for novel feeds and better proteins. In this sense, Pacific thread herring (Ophistonema libertate) contains high-quality proteins suitable to produce protein hydrolysates (PH) with antioxidant activity for tilapia feeds. In this study, two Alcalase herring muscle PH were prepared at 10% and 30% degree of hydrolysis (DH) and were supplemented on two formulated feeds, FH10 and FH30 respectively. One hundred eighty tilapia juveniles were fed with the experimental and a control feed (CF) for 6 weeks and then submitted to an acute stress by temperature increment for 24 hours. The results revealed that organisms fed with the FH10 shown the highest (p < 0.05) weight increment compared to the other feeds, showing a better protein yield. The enzymatic activity of superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx) measured in Nile tilapia livers was influenced by the experimental feeds, the organisms fed with FH10 exhibited the highest activity in SOD and CAT and the best productive performance, while the tilapias fed with FH30 showed an elevated GPx activity, suggesting that herring muscle PH in feeds are a suitable option to bring a potential benefit for Nile tilapias.