Effects of Anti-phospholipase A₂ on the Growth of Rainbow Trout

Abstract

Ingestion of a meal stimulates an inflammatory response in the gut of most vertebrates as the first line of defense against food-borne pathogens. In terrestrial farm animals, blocking gut inflammation with antibodies to the phospholipase A₂ (PLA₂) enzyme results in improved growth and feeding efficiency. Phospholipase A₂ is a rate-limiting enzyme in the biochemical pathway that leads to the production of prostaglandins and leukotrienes, which are key mediators of the gut inflammatory response. The purpose of the present investigation was to test the effects of anti-phospholipase A₂ (aPLA₂) on the growth of rainbow trout Oncorhynchus mykiss. The antibody was mass-produced by injecting laying hens of the domestic chicken Gallus gallus domesticus with PLA₂, collecting the antibody-rich eggs, and preparing an egg powder that was then top-dressed onto standard fish diets. There were three treatment groups: Control, 0.15%, and 0.30% aPLA₂ egg powder added to an extruded Silver Cup steelhead (anadromous rainbow trout) diet (45% protein, 16% fat). There were six 115-L tanks per treatment, and each was stocked with 12 fish. The fish were carefully fed to apparent satiation once daily. Total feed input to each tank was recorded. After 2 months, fish in the 0.15% and 0.3% treatment groups grew 11.1% and 27.8% greater, respectively, than controls. Feed conversion ratios in the control, 0.15%, and 0.30% treatment groups were 0.93, 0.93, and 0.86, respectively. It is concluded that aPLA₂ can be used as a feed additive to enhance the growth of rainbow trout.