Better Lambing Rates In The South

Press, Volume CVIII, Issue 31835, 13 November 1968, Page 29

Better Lambing Rates In The South

For many years, the South Island has returned better lambing percentages than the North Island. Why the difference?

Writing in the 1968 edition of the Perendale handbook, the founder of this breed (Sir Geoffrey Peren, of Palmerston North) suggests the difference may lie in management.

“For years suggestions have been put forward to account for the fact that lambing percentages in the southern half of the South Island are invariably higher than in any other provinces of the North Island,*’ he writes.

“More often than not, certain aspects of the climate are held to be responsible—to influence the number of' eggs shed by the ewe at tupping. But data collected by the Romney survey show that the ewe is not altogether to blame—that management also plays an important part. “To put the position in a nutshell, whereas the percentage of ewes lambing twins may account for a third or a half of the difference between the North and the South, according to the season, the remainder is made up of dry sheep and deaths, of which at least a

certain proportion can be charged to less careful management.

“This statement may be challenged, but it is hard to account for a proportion of the losses in any other way.

“Take the case of dry ewes: The figures appear to be consistently in favour of the South Island, only by 2 to 3 per cent, but one of the several minor contributions which make up the major differences in the percentages of lambs docked. “The figure for ‘dry/dry’ ewes, be it noted, is bigger than that for ‘wet/dry’ ewes, which suggests that less care is taken in the North to cull for infertility—it is hardly reasonable to assume, in the absence of reliable data, that the rams are responsible, year after year. “Such a theory would have to assume an effect on the fertility of the rams of either climate, type, strain or management or a combination of two or more of these. “Since there has been no word of a greater incidence in the north of disease causing sterility in rams, or abortion in ewes, the regular difference in the percentage of ‘wet/dry’ ewes in favour of the South suggests a heavier culling for shy breeding, and better care and nutrition of the pregnant ewes, in particular during the first month after

conception, when it has been shown that the embryo can easily be lost. “It may be claimed that a greater rate of development in the North has necessitated a faster build-up in numbers in mauy flocks, but this would not account for the greater number of deaths in lambs. For example, the figure for lambs lost between birth and docking at three days is higher for the North. “The question is why should these losses, due in the main to weak lambs, be higher in the North. On the average, the climate should be easier on the pregnant ewe and more favourable for the new-born lamb. It cannot be a matter of low temperatures. Does rainfall and its distribution play an important part, or is it a case of management —a more regular feed supply to the pregnant ewe in the South where the provision of crops for winter feed is essential?