A pre-partum lift in ewe nutrition from a high-energy lick or maize or by grazing Lotus uliginosus pasture, increases colostrum production and lamb survival

This experiment tested the hypothesis that a lift in the nutrition of ewes, before lambing, to increase colostrum production would enhance lamb survival. In all, 261 mature Corriedale ewes, each with a single fetus from a synchronised mating, grazed native pasture to day 130 after mating; at which point they were weighed, condition scored and allocated to graze either native pasture or a pasture dominant with Lotus uliginosus. Five days later (14 days before the expected start of lambing) the ewes were allocated to one of four treatments and fed: (I) native pasture alone, (ii) native pasture plus a commercial high-energy lick, (iii) L. uliginosus pasture alone or (iv) L. uliginosus pasture plus whole maize. The weight, viscosity and concentration of components and immunoglobulin G in the colostrum that had accumulated at parturition, were measured for 10 ewes in each treatment. The lambs that survived to 20 days of age from the 221 ewes that were not milked, were recorded. The ewes supplemented with the lick or maize grain and those that grazed the L. uliginosus pasture alone accumulated two to three times more colostrum at birth than the ewes that grazed native pasture alone (396, 635 and 662 g v. 206 g; P < 0.01). The colostrum from the ewes that grazed only native pasture was more viscous (lower score) than that from the ewes supplemented with the lick or maize grain or the ewes that grazed the L. uliginosus pasture alone (scores of 4.1 v. 6.2, 6.5 and 6.4, P < 0.001) and, not surprisingly, the concentration of lactose in the colostrum of the ewes fed only native pasture was also much lower (1.1% v. 3.0%, 2.8% and 2.6%; P < 0.001). The survival of lambs from the ewes fed only native pasture was less than that of the lambs from ewes fed native pasture plus the commercial lick (81.8% v. 95.5%; P < 0.05) or the L. uliginosus pasture alone (92.4%, P < 0.05), and also tended to be lower than that for lambs born to ewes fed L. uliginosus pasture plus maize (91.8%, P = 0.08). The concentration of glucose in the blood of the lambs from the ewes that grazed only native pasture was lower than that of the other lambs (42.1 v. 60.2 ng/ml, P = 0.012). We conclude that the marked increase in colostrum production associated with the lift in ewe nutrition, just prior to lambing, enhanced lamb survival.