GROWTH ENHANCEMENT FOLLOWING DIETARY DELIVERY OF RECOMBINANT PORCINE SOMATOTROPIN TO DIPLOID AND TRIPLOID COHO SALMON (ONCORHYNCHUS-KISUTCH)

Diploid (2n) and triploid (3n) coho salmon were fed upon control (diet 1), recombinant porcine somatotropin (rpST)-supplemented (diet 2; 20 mug rpST/g body wt/day) or rpST/antacid/detergent-containing feed (die t 3; 20, 100 & 20 mug/g body wt/day respectively) for 16 wk. Fish were weighed and measured bimonthly and their relative performances assess ed. By wk 4, 2n and 3n groups fed upon diet 2 were significantly heavi er and longer than control 2n fish. At the termination of the trial, d iet 3 fed animals were greater in weight than all other treatment grou ps. Diet 3 salmon also returned better feed conversion efficiencies th an either diet 1 or 2 groups. RpST therapy induced a 28.7% and 60.2% i ncrease in group wt for 3n diet 2/3 coho versus (-vs-) controls. Likew ise, 2n rpST-treated fish increased wt -vs- 2n control coho by 17% and 50% respectively over the same period. No differences were recorded b etween groups for body moisture, but diet 2, 3n and both diet 3 groups exhibited decreased condition factors when compared to control fish ( p less-than-or-equal-to 0.05).