Assessment different selection criteria for reproduction rate in Dormer and S.A. Mutton Merino sheep. 2. Luteinizing hormone c

Author: N.M. Kritzinger, H.W. Stindt & J.M. van der Westhuizen
Year: 1984
Issue: 2
Volume: 14
Page: 84 - 87

Data of all the lambs born to the Elsenburg Dormer (n = 303) and SA Mutton Merino (n = 325) flocks during the 1977 and 1978 lambing seasons as well as their female relatives were used to study various aspects regarding the use of prepubertal serum LH levels as a possible physiological selection criterion for reproduction rate in sheep. Results obtained showed a significant effect (P 0,01) of breed and sex on the serum LH levels of lambs at different ages. Correlations between serum LH measurements at 30, 60 and 90 days of age, however, were low and insignificant, indicating that this parameter is of low repeatability and of little or no value, if the age at which measurements are taken is not defined. Neither sire not birth type had any significant effect on the prepubertal serum LH levels for either of the two breeds and no positive relationship between serum LH levels of lambs and the reproductive performance of their female relatives or between serum LH levels of ewe lambs and their own subsequent reproductive performance could be established. It thus seems that prepubertal serum LH levels in lambs offer little, if any, advantage as a selection criterion to improve the reproductive performance of sheep.



Keywords: reproduction rate, selection criterion, Serum LH levels, sheep
Read article