Feeding Prolific Ewes in Late Pregnancy and Rearing Triplet Lambs.

Abstract

In prolific flocks a significant proportion of ewes give birth to 3 or more lambs. It was considered that the birth weight of triplet lambs, and also of twins, could be increased by offering ewes a higher than normal level of concentrate supplementation in late pregnancy. Trials for the evaluation of rates of supplementation were conducted during the years 2000 and 2001. In-wintered ewes were offered silage ad libitum. Based on scanning results groups of twin-bearing (twins) and triplet-bearing (triplets) mature ewes were offered one of three rates of supplementation in late pregnancy. The lower rate in each case was set at a level considered appropriate for twins or triplets. Two groups of twin-bearing hoggets were offered either a low or high rate of supplementation. Average silage intake over the last 6 weeks of pregnancy was 0.8 to 0.9 kg dry matter per day. Intake by triplets was about 95 percent of that by twins, while intake by triplets at the high rate of supplementation was 90 percent of that at the low rate. Total dry matter and metabolisable energy intakes were increased by supplementation. Triplets had significantly lower condition score than twins at lambing but the rate of supplementation did not affect condition score. Average condition score of all ewes decreased by 0.6 units between mid pregnancy and lambing, a decline that is considered acceptable.Average birth weight of triplet lambs was about 1 kg lower than for twins from mature ewes. The high rate of supplementation increased the birth weight of twins by 0.51 kg and triplets by 0.26 kg. Birth weight of twins from hoggets was not affected by the rates of supplementation offered. The rearing of triplet lambs by their dam, rather than cross fostering or artificial rearing the third lamb, may be a useful option in prolific flocks. Previous research findings showed that triplets were reared successfully by selected ewes when the ewes were offered concentrate supplementation for 4 to 6 weeks at pasture post lambing, and the lambs received creep feed from birth to sale. Trials were carried out over two years to assess the response to concentrate supplementation of ewes at pasture post lambing and creep feeding lambs with a view to reducing the quantity and cost of concentrates for rearing triplet lambs. Concentrates at 1 kg/ewe/day were offered to ewes at pasture for 3 or 6 weeks post lambing. Creep feed was available to lambs from week 1 and offered at one of three rates : 300g/day to age 10 weeks: 300 g/day to sale, or 600 g/day to sale. Lambs were drafted for sale by weight and condition and carcasses were classified according to MLC standards. There was no response to feeding concentrates to ewes for 6 weeks rather than 3 weeks in this situation when grass supply was considered adequate. Weaning weight was increased by offering creep feed to lambs to 14 rather than 10 weeks. All lambs were finished to acceptable carcass weights and grades. The main effect of continuing creep feeding lambs to sale was to reduce the average age at sale. The medium and high levels of creep reduced the average age at sale by 20 and 45 days respectively compared with the low rate. However the total quantity of concentrates offered per ewe plus 3 lambs was about 60, 120 and 180 kg for the vi low, medium and high rates of creep respectively, including 21 kg concentrates for the ewes post lambing.