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Effect of daylength at birth and lunar phase on the occurrence of first oestrus in beef heifers

Published online by Cambridge University Press:  02 September 2010

R. C. Greer
R. C. Greer
Affiliation:
Department of Agricultural Economics and Economics, Montana State University, Bozeman, Montana 59717, USA
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Abstract

Data records from 556 beef heifers which included age at first oestrus (AFE) were used to test the null hypotheses: 1) daylength at birth is not a determinant of AFE in beef females; and 2) there is not an association between the day on which first oestrus occurred and the lunar phase.

The effect of daylength at birth was measured by forming a variable, X1 where X1 = sine (X1′ 360/365·25)°, and including it among the set of variables in a multiple linear regression equation with AFE as the dependent variable. The resultant estimated coefficient on X1 was -3·617 with a standard error of 21·32, and led to the conclusion that daylength at birth was not a factor which affected AFE in this group of beef heifers.

The lunar phase hypothesis was tested by forming the frequency distribution of the 556 observations of first oestrus over the 30-day lunar cycie. The chi-square test was applied with the theoretical (hypothesized) distribution being the uniform distribution. The value of the test statistic was such that the null hypothesis would not be rejected even with an a value approaching 0·50. Additionally, coefficients of autocorrelation calculated for lag phases of 7, 14 and 21 days were quite small. Thus it was concluded that the occurrence of first oestrus was uniformly distributed over the lunar cycle.

Type
Research Article
Information
Animal Production , Volume 39 , Issue 1 , August 1984 , pp. 59 - 63
Copyright
Copyright © British Society of Animal Science 1984

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References

REFERENCES

Ezekiel, M. and Fox, K. A. 1963. Methods of Correlation and Regression Analysis. 3rd ed., pp. 335–337.Google Scholar
Greer, R. C., Whitman, R. W., Staigmiller, R. B., and Anderson, D. C. 1983. Estimating the impact of management decisions on the occurrence of puberty in beef heifers. J. Anim. Sci. 56: 30–39.Google Scholar
Hawk, H. W., Tyler, W. J. and Casida, L. E. 1954. Some factors affecting age at puberty in Holstein- Friesian heifers. J. Dairy Sci. 37: 252–258.Google Scholar
Lindgren, B. W. and McElrath, E. W. 1966. Introduction to Probability and Statistics. MacMillan, New York.Google Scholar
Little, W., Mallinson, C. B., Gibbons, Diana N. and Rowlands, G. J. 1981. Effects of plane of nutrition and season of birth on the age and body weight at puberty of British Friesian heifers. Anim. Prod. 33: 273–279.Google Scholar
Menge, A. C., Mares, S. E., Tyler, W. J. and Casida, L. E. 1960. Some factors affecting age at puberty and the first 90 days of lactation in Holstein heifers. J. Dairy Sci. 43: 1099–1107.CrossRefGoogle Scholar
Roy, J. H. B., Gillies, Catherine M., Perfitt, M. W. and Stobo, I. J. F. 1980. Effect of season of the year and phase of the moon on puberty and on the occurrence of oestrus and conception in dairy heifers reared on high planes of nutrition. Anim. Prod. 31: 13–26.Google Scholar