Birth weight and behaviour of crossbred lambs from Merino ewes supplemented with expeller canola meal or lupin seed

Abstract

Proc. Aust. Soc. Anim. Prod. I996 Vol. 2 I BIRTHWEIGHT AND BEHAVIOUR OF CROSSBRED LAMBS FROM MERINO EWES SUPPLEMENTED WITH EXPELLER CANOLA MEAL OR LUPIN SEED J.T.B. MILTON, P.M. MURPHY, A. COUTY and C.M. OLDHAM Faculty of Agriculture, The University of Western Australia, Nedlands, W.A. 6907 In a pen study, Masters and Mata (1996) showed that reproducing ewes supplemented with expeller canola meal (ECM, canola seed residue heated to 110O C during mechanical extraction of oil) increased their wool growth and fibre diameter over ewes supplemented with lupin seed. Single lambs from ewes fed ECM in their study weighed less (4.9 vs 5.4 kg) possibly due to residual glucosinolates in ECM affecting iodine metabolism. In a field study to investigate the value of ECM to improve wool production in reproducing ewes, we also measured the birthweight, behaviour and level of thyroid hormones of lambs from ewes supplemented with either whole lupin seed or pellets containing ECM. Two groups of Merino ewes pregnant to White Suffolk rams and with similar ratios of single to twin bearing ewes were offered oaten silage ad libitum. One group was fed a base supplement of 230 g/head.day of pellets containing 65% crushed expeller canola meal, 24% milled lupin seed, 10% rolled oat grain and 1% calcium hydroxide (canola pellets). The canola pellets were made with a steam pellet mill and reached 80�C. The other group was fed a base supplement of 200 g/head.day of whole lupin seed. These 2 base supplements, each plus equal increasing quantities of whole lupin seed, provided all ewes with the same amount of supplementary crude protein and metabolisable energy to meet their requirements during the 4 weeks pre- and 4 weeks post-partum. The ewes lambed over 14 days with the mid-point of lambing 29 days after supplementation commenced. All lambs were weighed, ear tagged and had their sex and birth type recorded at birth. Only single lambs born during daylight hours were monitored for behavioural activity in the first hour after birth. Ten single lambs from ewes fed canola pellets and 8 from ewes fed lupins were observed every 10 seconds to record their activity of lying, standing or standing and sucking. Plasma was taken from single lambs (15 from ewes fed canola pellets and 16 from ewes fed lupins, average age 24 days) and analysed for thyroid hormones (T3 and free T4) by radioimmunoassay. Table 1. Birthweights, time taken to stand, time spent standing and spent sucking, and plasma concentrations of thyroid hormones for lambs from ewes supplemented with canola pellets or lupin seed Single lambs from ewes fed canola pellets took 20 minutes longer to stand and stood for 16 minutes less in the first hour after birth than single lambs from ewes fed lupin seed. It is thus surprising that the time spent sucking by single lambs did not differ between groups. The low activity of single lambs from ewes fed ECM does not appear to be associated with disturbed iodine metabolism since the levels of thyroid hormones in the single lambs were not affected by maternal diet. Despite the differences in both the behaviour of singles and the birthweights of twins, lamb survival to 29 days within each birth type was similarly high (singles - 92%, twins - 83%) for the 2 feed groups. MASTERS, D.G. and MATA, G. (1996). Proc. Aust. Sot. Anim. Prod. 21: 368. 375