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Effect of Heterosis and Maternal Influence on Gestation Length and Birth Weight in Reciprocal Crosses among Angus, Charolais and Hereford Cattle1
J. A. Sagebiel2, G. F. Krause, Bob Sibbit, L. Langford, A. J. Dyer and John F. Lasley
University of Missouri, Columbia 65201
Abstract
A study involving 869 calves of Angus, Charolais and Hereford breeds and all reciprocal crosses among them was conducted to determine the effects of heterosis and maternal influence on birth weight and length of the gestation period. Six years' data have been analyzed by least-squares procedures.
All three main effects (bull breed, cow breed and year) were found to exert a significant influence on both traits. The interaction between bull breed and year also was significant in most analyses.
The lack of a significant interaction between bull breed and cow breed indicates that heterosis is not important for these traits. Comparisons involving each two-breed cross verify this conclusion.
Maternal effects on length of the gestation period were found to be significant, which indicates that the fetus is not always responsible for variation in the gestation period. No significant maternal effect on birth weight was observed.
Of the straightbreds, the Herefords had the longest gestation period, but both Herefords and Charolais had significantly longer gestation than the Angus.
Charolais and Hereford bulls significantly delayed parturition and increased birth weights of calves born to Angus cows. Angus bulls slightly decreased gestations and birth weights of calves born to Hereford cows while Charolais bulls significantly increased birth weights of calves from Hereford cows.
Footnotes
J. A. Sagebiel2, G. F. Krause, Bob Sibbit, L. Langford, A. J. Dyer and John F. Lasley
University of Missouri, Columbia 65201
Abstract
A study involving 869 calves of Angus, Charolais and Hereford breeds and all reciprocal crosses among them was conducted to determine the effects of heterosis and maternal influence on birth weight and length of the gestation period. Six years' data have been analyzed by least-squares procedures.
All three main effects (bull breed, cow breed and year) were found to exert a significant influence on both traits. The interaction between bull breed and year also was significant in most analyses.
The lack of a significant interaction between bull breed and cow breed indicates that heterosis is not important for these traits. Comparisons involving each two-breed cross verify this conclusion.
Maternal effects on length of the gestation period were found to be significant, which indicates that the fetus is not always responsible for variation in the gestation period. No significant maternal effect on birth weight was observed.
Of the straightbreds, the Herefords had the longest gestation period, but both Herefords and Charolais had significantly longer gestation than the Angus.
Charolais and Hereford bulls significantly delayed parturition and increased birth weights of calves born to Angus cows. Angus bulls slightly decreased gestations and birth weights of calves born to Hereford cows while Charolais bulls significantly increased birth weights of calves from Hereford cows.
Footnotes