Submitted to: Journal Of Poultry Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/6/1999
Publication Date: N/A
Citation: Interpretive Summary: Selection of domestic animals for rapid growth alters the pattern of organ growth. The growth of supply organs such as the heart and liver precede that of muscle growth. This has been proposed to occur early in embryonic development. As tissue function matures, organ function increases at the expense of growth. Little is known of this relationship in the turkey embryo. This study was conducted to determine differences in growth and glycogen concentration of supply and demand tissues in turkey embryos whose parents were selected for either growth or egg production. The results of this study suggest that selection for egg promotion affects embryonic growth and organ development differently than does selection for growth. Dietary iodide seems to influence embryo development. The results of the study will be of interest to other scientists and extension people.
Technical Abstract: In prior studies it has been shown that the growth of turkey embryos was dependent upon maternal dietary iodide as well as the genetic selection of the sire and dam that affects egg size. The current study posed the question of which organ systems are responding to the genetics and maternal thyroid function. Embryos from genetic lines selected for 16 week body weights grew at the same rates as non-selected embryos until 21 days of incubation. Genetic based differences in growth of the embryos selected for increased 16 week body weights could be accounted for in increased liver and heart tissue growth at the expense of muscle growth. Muscle growth increased in the growth selected line prior to pipping. Muscle growth was affected less when dams were selected for egg production. Muscle growth was slowed in egg line embryos compared to that of RBC1 but liver and heart growth were slowed at internal and external pipping stages in egg embryos compared to RBC1. When iodide was included in the maternal diet, genetic ability to increase muscle growth may occur earlier in development and to a greater extent in growth selected than in egg production selected embryos. Measurements indicated decreased tissue glycogen in liver, heart and muscle of selected lines may be one possible mechanism by which growth and or organ function may come in conflict.