Havaintoja ja laskelmia lehmävasikoitten sekä hiehojen kasvusta Viikin koetilan karjassa

Authors

• Aarne Mäkelä Helsingin yliopiston kotieläintieteen laitos, Viikin koetila

DOI: https://doi.org/10.23986/afsci.71500

Abstract

In the Ayrshire herd of the University Farm Viik the calves have been weighed at birth since 1947, and the weight and the height at withers measured at stated intervals since 1952. Similarly heifers have been weighed and measured at the ages of 1 and 1 ½ years. In the feeding of heifer calves a standard feeding system has been used in which the allowance of milk and of concentrates has been the same at the same age irrespective of the birth weight and of the weight of the mother. Hay and water, however, have been given ad libitum since birth. The total allowance of whole milk per calf has been about 270 kg, of skimmilk about 860 kg, and of concentrates until six months of age about 68 kg. The main results as to the weights and the heights at withers were as follows. The mean of the birth weight of 288 heifer calves was 32.1 ± 0.25 kg, the standard deviation being 4.3 ± 0.18 kg, and the coefficient of variation 13.4 ± 0.57 % when the subject matter included only the single birth cases. The variation of birth weight can be seen from table page 305. The birth weight of the bull calves was on an average 2.4 kg (P <0.001) more than that of the heifer calves. The calves of the first calving were on an average 2.5 kg (P <0.01) lighter than those of the second, third, and fourth calving. The gain in weight of heifer calves is in the two first months from birth relatively independent of the birth weight. Thereafter the calves with a great birth weight grow faster than the calves with a small birth weight. Figures 1 and 3 show the weight developments of heifer calves and of heifers. The increase in height at withers seems to be relatively independent of the birth weight (Figures 2 and 4). The relative rate of growth measured as a gain in weight and increase in height at withers is greater in calves with small birth weight. The relatively faster gains in weight of calves with small birth weight during the first months of life may principally be due to the standard feeding system. In the two first months the increase in weight of the bull calves is about the same as that of the heifer calves. Later the bull calves grow faster. As to the live weight the standard deviation is relatively greater, the measuring more accurate, and the gain relatively faster than in the case of the height at withers, the individuality of the growth of calves manifests itself more clearly in weights than in the heights at withers. The correlation coefficient between the weight and the height at withers was for the heifer calves r = +0.53 (P<0.001) the influence of age being eliminated. The weight and the height at withers thus vary considerably independently of each other. Therefore it is advisable in observing the growth development of calves not only to weigh the animals but also to measure their height at withers.