Hogget liveweight-oestrus relationship among sheep breeds

H.H. Meyer, R.L. French

Ruakura Animal Research Station, Hamilton

Proceedings of the New Zealand Society of Animal Production. 1979, 39: 56-62

Within the F₁ progeny of nine sire breeds, a positive relationship was observed between hogget liveweight and incidence of hogget oestrus. Across breeds, however, there was no relationship between mean hogget weights and either proportion of hoggets showing oestrus or number of oestruses per hogget. Finn x Romney F₁ hoggets showed a higher incidence of oestrus (88%), and straightbred Romneys a lower incidence (25%), than the remaining seven breeds, which ranged from 52% to 67%.

The ovulation rate was very high for Booroola x Romney (1.69) and Finn x Romney (1.42) F₁ ewe hoggets. Remaining breeds ranged from 1.02 to 1.11 ova per ovulating hogget. Within the two high ovulating breeds, twin ovulators averaged 6% heavier than single ovulators.

Number of hogget oestruses was positively related to subsequent ovulation rate observed at 1½ years of age. Because numerous factors (such as hogget and 1½ year liveweights) are confounded, it cannot be assumed that the observed phenotypic relationship is genetic in origin.

Keywords: NZSAPAB;

Last Updated 12-09-1998