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Title: EFFECTS OF GROWTH HORMONE INJECTION TO EMBRYOS ON GROWTH AND MYOSIN HEAVY CHAIN ISOFORMS IN GROWING TURKEYS.

Author
item Maruyama, Kimiaki - Kim
item KANEMAKI, N - AZABU UNIVERSITY
item Proudman, John

Submitted to: Comparative Biochemistry and Physiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/10/1995
Publication Date: N/A
Citation: N/A

Interpretive Summary: Growth is regulated in part by circulating hormones. In this study, we examined possible beneficial effects of growth hormone given before hatching on turkey growth after hatching. Such "imprinting" may play an important role in development. When eggs were injected with growth hormone on 26-day of incubation, body weights, shank length and muscle weights of turkeys were increased and plasma growth hormone concentrations were elevated. While muscle growth rates were increased, the sequential appearance of isoforms of myosin heavy chain which is one of the major muscle proteins, were delayed. These findings strongly suggest that a better understanding of prehatch effects of growth hormones might provide techniques for improving turkey production.

Technical Abstract: Effects of embryonic imprinting with growth hormone (GH) on growth and myosin heavy chain (MyHC) isoforms in Pectoralis muscle were determined by injecting turkey embryos with ovine growth hormone (oGH) at a dose of 10 æg three times a day. Injections were made on days 20 and 26 (Treatment 1), on days 14 and 20 (Treatment 2) or days 14 and 26 (Treatment 3) of incubation. In Treatment 1 poults, plasma GH concentrations were elevated at 3 days post-hatch and in Treatment 3 poults, plasma GH concentrations were elevated at 15 days post-hatch, as compared to control poults. At 4 weeks of age, in males, body weights, shank length and weights of Pectoralis, Gastroconemius and Sartorius muscles were increased in Treatment 3, and in females, body weights, shank length and weights of Gastrconemius muscle of female turkeys were increased in Treatment 1. The growth rate of female turkeys from 4 weeks through 16 weeks was increased by Treatment 1. Treatment 1 resulted in a delay in the transition from the embryonic MyHC isoform to the neonatal MyHC isoform and to the adult MyHC isoform. Treatment 3 induced an earlier appearance of the adult MyHC isoform. No effects on body and muscle growth and MyHC isoforms were observed by Treatment 2.