Evaluation of the potential for using a chinook salmon (Oncorhynchus tshawytscha) pituitary extract versus bovine growth hormone to enhance the growth of coho salmon (Oncorhynchus kisutch)

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Abstract
Groups of yearling coho salmon, held at 10 °C and on a 12-h photoperiod, were injected intramuscularly once weekly with 10 or 100 μg of a chinook salmon pituitary extract (oncPE)/g body weight, 0.1–10 μg (9.2 × 10−3 IU) of bovine growth hormone (bGH)/g body weight, solvent, or no treatment for 70 days.Both oncPE and bGH treatment stimulated growth in length and weight. The potency of oncPE per unit weight was about one-ninth that of bGH. The lowest effective bGH dosage was 3.2 μg/g body weight, while 10 μg/g body weight induced the maximum growth response. Coho given 100 μg of oncPE/g body weight had the highest growth rates. Condition factors of bGH-treated fish were depressed when the dosage exceeded 1.0 μg/g body weight.It is concluded that use of bGH is more economical than the available pituitary extracts or purified piscine growth hormones for coho salmon culture. Two alternatives to the use of native growth hormones in salmon culture are discussed.