J. Anim Sci.
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J. Anim Sci. 1973. 36:457-465.
© 1973 American Society of Animal Science
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Factors Influencing Milk Yield of Hariana Cattle

L. O. Ngere1, R. E. McDowell, S. Bhattacharya2 and H. Guha3

Cornell University,,4 Ithaca, New York 14850 and Central Livestock Research-cum-Breeding Station, Haringhata

Abstract

OVER 4,000 lactation records, irrespective of length up to 300 days, for one or more calvings of 1,460 Hariana cows were used to determine the relative contribution of certain environmental factors to lactation milk yield. There were 42% of records with recorded conditions that could have made them abnormal in length and yield. Reproductive disorders, physical injury, calf died, cow died and cow sold reduced both length of lactation and milk yield significantly. Aftosa, mastitis and miscellaneous causes were unimportant. Loss of calf resulted in short lactations and 16.4% less yield (P<.05). System of roughage feeding—green vs. dry—was not important. Although frequency of milking was confounded by years, 3X gave about 12% higher yield than 2X. Effects of season of calving, year, age of calving, the interactions and length of lactation were significant (P<.05) with the latter accounting for 45% of the total variation in yield. Days open, days dry and calving interval accounted for only 2 to 6% of the total variance in lactation yields. The proportional change in production with advancing age was similar to that for European breeds. Adjustment factors for age and short records due to death of calf are presented. This study clearly shows that the customary procedure of deleting short lactation records when attempting to evaluate differences among cows of breeds indigenous to tropical areas will lead to serious biases. Dropping short records removes a large proportion of low yielders where no cause can be identified but such a procedure removes only a small portion of the records where environmental disturbances could be a factor influencing the estimated value of cows. Tendency for the vast majority of cows to cease lactation following death of calf shows this factor should be taken into consideration where the milking process is carried out in the presence of the calf. Although milk yield may appear associated with age, adjustment for age differences should only be considered after taking into account possible effects of lactation length, the time after starting the herd and year effects. It is also evident that in adjusting to a common age, the age of calving is more appropriate than lactation number.

Footnotes

1 Present address: Animal Science Department, University of Ghana, Legon.

2 Present address: FAO Technical Assistance Group, Syrian Arab Republic, Damascus, Syria.

3 Present address: Directorate of Animal Husbandry, West Bengal, Calcutta—1, India.

4 Department of Animal Science.






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Copyright © 1973 by the American Society of Animal Science.