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Analysis of some factors which affect the productivity of beef cows and of their calves in a marginal rainfall area of Rhodesia 2. The yield and composition of milk of suckling cows

Published online by Cambridge University Press:  02 September 2010

F. D. Richardson ,
J. Oliver  and
G. P. Y. Clarke
F. D. Richardson
Affiliation:
Mlezu Rural Technical Institute, PO Box 311, Que Que, Rhodesia
J. Oliver
Affiliation:
Department of Agriculture, University of Rhodesia, PO Box MP 167, Mount Pleasant, Salisbury, Rhodesia
G. P. Y. Clarke
Affiliation:
Department of Agriculture, University of Rhodesia, PO Box MP 167, Mount Pleasant, Salisbury, Rhodesia
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Summary

The milk production of three groups of cows grazing on veld and receiving different amounts of concentrates during winter and the first 8 weeks of lactation was studied over four successive calving seasons. Calves were weaned at either 150 or 240 days.

Cows offered most concentrates and those whose calves had been weaned early in the previous year produced more milk per lactation (P < 0·01) than other cows but weaning age did not affect yield/cow per year. Data for each treatment in each year were considered as a separate class. Regression analyses showed that milk yield increased with cow weight at calving and with calf birth weight. Changes in cow weight during early lactation, after adjusting for initial weight, were directly related to milk yield.

In a concurrent experiment, three groups of heifers were confined in pens and given sufficient amounts of a complete diet to promote either gain, maintenance or loss of weight during lactation. Heifers that gained or maintained weight produced significantly (P<0·01) more milk of a higher solids-not-fat and protein content than those which lost weight. Food intake had a significant (P < 0·01) positive effect on milk yield but the effects of weight and weight change on milk yield were negative after adjusting for food consumption.

Type
Research Article
Information
Animal Production , Volume 25 , Issue 3 , December 1977 , pp. 359 - 372
Copyright
Copyright © British Society of Animal Science 1977

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References

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