Hill country sheep production

Abstract

Data from 484 6-year-old ewes over the period 1969 to 1971 were used to study the effects of flock and vear on oestrous incidence and ovulation rate at first, third, and fifth oestrus. The sheep were from two straightbred Romney (RCR, RER) and first-cross (Ft>, secondcross (F2), and third-cross (F:J) Border Leicester X Romney flocks that had been grazed together from birth at the Whatawhata Hill Country Research Station. Oestrous activity extended from early March, the proportion of ewes showing oestrus increasing rapidly to a peak in late March, then declining after mid June. There were no differences between flocks in oestrous activity. Total ovulations observed over the first plus third oestruses were 2.5,2.6, 3.1,2.9, and 3.1, and over the first plus third plus fifth oestruses were 3.7, 3.9,4.6. 4.3, and 4.7 respectively for the RCR, RER, Fj , F2, and Fa flocks. These were related to the number of lambs born per lambing over the previous four lambings (2-to 5-year-old), and to pre-tupping live weights.