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Gestation length

Big Muddy rancher

Well-known member
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
 

Shelly

Well-known member
Thanks BMR. The bull we bought is supposedly a Black Angus, but I'm thinking he may only be half. The other half is either Simmental or Maine Anjou, birthweights are all over the scale but so far good luck. The cows are still calving early, anywhere from 6 to 9 days early. In the other post about genetics, someone had mentioned that maybe this bull carried a certain gene that causes his calves to come earlier also. I'm starting to believe it's quite possible! At this rate, most of the cows we sold to our friend will be done calving before the end of January.
 

Denny

Well-known member
Shelly said:
Thanks BMR. The bull we bought is supposedly a Black Angus, but I'm thinking he may only be half. The other half is either Simmental or Maine Anjou, birthweights are all over the scale but so far good luck. The cows are still calving early, anywhere from 6 to 9 days early. In the other post about genetics, someone had mentioned that maybe this bull carried a certain gene that causes his calves to come earlier also. I'm starting to believe it's quite possible! At this rate, most of the cows we sold to our friend will be done calving before the end of January.

He should have some money making calves come fall either way.
 

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