...with later lambing schedule

Waimarino Bulletin, Volume 1, Issue 38, 13 March 1984, Page 11

...with later lambing schedule

Last Spring an article was presented to highlight the need to lamb later. In the Waimarino a feed shortage is characteristic at lambing. Feed shortages at this time are known to reduce ewe milk production and lamb growth rates. For this reason it is important to time lambing with Spring pasture supply, (see graph). A trial done recently in Southland highlighted the need to time lambing with pasture growth. Three lambing dates were compared: 6 September, 23 September, 6 October. Results showed: (a) Ewe liveweights were up to 14kg higher for later lambing dates after six weeks of lactation. Single rearing ewes were progressively heavier than twin rearing ewes during lactation of 6kg by 6 weeks and 10kg by 12 weeks; (b) Later lambing increased ewe greasy .wool •roduction between June nd January by up to 0.41kg; (c) Later lambing increased lamb growth in the first six weeks of lactation from 208 to 279 g / head / day (40%) for singles

and 135 to 215 g/head/day (60%) for twins. As a result oft the high growth rate of laihbs in the late lambing group there was no difference in the weaning weight of lambs, when all lambs were weaned on 5 January. Conclusion Even though the late born lambs are four weeks younger than the early born lambs, weaning weight of lambs is largely unaffected by lambing date if weaning at a constant date, say 5 January. An optimal lambing date will result in higher ewe fleece weights and higher ewe weaning weights. From a management point of view, a heavier ewe at weaning means it is well on its way to achieving a good tupping weight at its next mating. It is my view that to achieve the optimal lambing date for the Waimarino, rams should go out between 15 and 25 April depending on location and stocking rate on the property. General Comments (a) One common argument

for early lambing is to get lambs away to the works early. This used to apply when the freezing companies paid pre-Christmas premiums for early killed lambs. Now the schedule doesn't alter over the killing season and is unlikely to over the next 12 months. (b) Timing lambing with pasture growth cuts costs of supplementary feeding. (c) General 'peace of mind' with farmers improves considerably with the knowledge that grass is available for lambing ewes. (d) Later lambing will not only give a more concentrated lambing but in most cases increase lambing percentage. This was a common observation with farmers who lambed later last year. Will Wilson Farm Advisory Officer