Dam line and sire line effects on turkey embryo survival and thyroid hormone concentrations at the plateau stage in oxygen consumption

Authors: CHRISTENSEN, V. - NORTH CAROLINA STATE; HAVENSTEIN, G. - NORTH CAROLINA STATE; ORT, D. - NORTH CAROLINA STATE; McMurtry, John; NESTOR, K. - OHIO STATE UNIVERSITY

Submitted to: Poultry Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/18/2007
Publication Date: 9/1/2007
Citation: Christensen, V.L., Havenstein, G.B., Ort, D.T., McMurtry, J.P., Nestor, K.E. 2007. Dam line and sire line effects on turkey embryo survival and thyroid hormone concentrations at the plateau stage in oxygen consumption. Poultry Science. 86:1861-1872.

Interpretive Summary: Survivability and viability of turkey embryos and poults are major issues confronting the domestic turkey industry. In turkeys, increased embryo death during tucking has been attributed to the female line, while increasing mortality at pipping has been associated with the male line. Commercial turkeys are the product of multiple genetic line crosses. Understanding gene expression patterns of thyroid hormones in turkey embryos derived from various breeding lines may provide clues to understanding the viability of commercial turkey embryos and neonates. The dam line and the sire line may independently affect embryo thyroid hormone concentrations. In this study, turkey embryo thyroid hormone concentrations were determined in plasma obtained from different sire and dam lines of breeding turkeys. Results of this study strongly indicate that the dam line and the sire line have distinct effects on turkey embryo thyroid hormone function. The effects are line-specific and dependent upon the selection history of the line. This data are the first to describe separate dam and sire effects on the inheritance of embryo thyroid function. This information will be of interest to other scientists and poultry geneticists.

Technical Abstract: Inheritance of embryo thyroid function was measured in lines of turkeys. Two lines that had been selected for either increased egg production (E) or increased 16-wk BW (F) and their respective randombred controls (i.e., RBC1 and RBC2) were examined. Reciprocal crosses of dams and sires from each selected line and its randombred control were made to estimate sire line and dam line effects. Orthogonal contrasts were used to determine if the differences found were due to the presence of additive, nonadditive, or maternal, sex-linked, or both, gene effects. With the data involved, sex-linkage and maternal effects could not be separated. Embryo survival was measured for all lines and their reciprocal crosses. Crossing the RBC1 sire and E dam also resulted in better embryo survival and lower death losses at pipping than for the other cross- or purelines. Reciprocal crosses of the F and RBC2 lines showed better total embryo survival, and they survived pipping better than the F or RBC2 purelines. Thyroxine (T4) and triiodothyronine (T3) concentrations differed between the reciprocal crosses at external pipping, but the effects were inconsistent for the 2 data sets. Reciprocal tests indicated that maternal, sex-linked, or both, effects were present for T3 concentrations at internal pipping in the E and RBC1 lines and at external pipping for the F and RBC2 lines. Reciprocal effects were significant for T4 at internal pipping for both data sets. The RBC1 sire embryos had significantly higher T3:T4 ratios than the E line sire embryos at internal and external pipping, and the pureline RBC1 embryos had consistently higher ratios than the pureline E embryos. The differences for the T3:T4 ratios between these 2 lines at internal pipping, external pipping, and hatch appeared to be consistently additive in nature, although significant nonadditive or heterotic effects were present for the ratio at external pipping. Similar effects on the T3:T4 ratio were observed for the F and RBC2 lines at external pipping.