Long-term effect of dietary protein supplementation on resistance to gastrointestinal nematode infections and production in young grazing Merino ewes.

Abstract

24A Long_term effect of dietary protein supplementation on resistance to gastrointestinal nematode infections and production in young grazing Merino ewes Kaidong Deng1, M.R. Knox2, C.W. Wong1 and J.V. Nolan1 1 2 Animal Science, University of New England, Armidale NSW 2351 CSIRO Livestock Industries, Locked Bag 1, Ar midale NSW 2350 kdeng3@metz.une.edu.aul Young sheep are more susceptible to internal parasite infections than older sheep, but immunity is enhanced by dietary protein supplementation (van Houtert et al. 1995; Datta et al. 1999). A study was made of the effect of protein supplementation of young grazing sheep on their later resistance to gastrointestinal nematodes. Twelve groups of 15 Merino ewe weaners 4_5 months old were allocated to 0.8 ha pasture plots and given cottonseed meal pellets daily for 10 weeks at the rates of 0, 85 or 170 g per head. All groups remained in their respective plots for a further 8 weeks after supplementation ceased, and were then treated with anthelmintic and grazed as one flock. Faecal egg counts (FEC) and liveweight gains (LWG) were monitored each 2 weeks up to Week 18, and then at Weeks 29, 42 and 52. Fleece weight was recorded at shearing at Week 31. Supplementation lowered FEC (P<0.05) during the feeding period and this effect persisted up to 8 weeks after supplementation ceased (P<0.05), but there was no significant carry_over effect at Weeks 29, 42 and 52 (Figure 1). Supplementation increased LWG during the 11 10 , epg) supplementation period and in the following 8 weeks (P<0.05); this effect was still apparent 19 weeks after supplementation ceased (Week 29) but not at Weeks 42 and 52 (Figure 2). Fleece weight was increased (P<0.05) by supplementation; mean weights � SEM were 2.12 � 0.02, 2.19 � 0.05 and 2.31 � 0.01 kg for the 0, 85 and 170 g/d, respectively. These results suggest that protein supplementation enhanced host resistance to gastrointestinal nematode infections and production in grazing young Merino ewes and that these benefits were carried over for at least 8 weeks. Datta, F.U., Nolan, J.V., Rowe, J.B., Gray, G.D. and Crook, B.J. (1999). Long_term effects of short_term provision of protein_enriched diets on resistance to nematode infection, and liveweight gain and wool growth in sheep. International Journal for Parasitology 29, 479_488. van Houtert, M.F., Barger, I.A. and Steel, J.W. (1995). Dietary protein for young grazing sheep: interactions with gastrointestinal parasitism, Veterinary Parasitology 60, 283_295. 9 8 7 6 5 4 3 2 4 6 8 10 12 14 16 18 29 43 52 Weeks af ter commencing supplementation 0g 85 g 170 g Figure 1 Mean � SEM faecal egg counts (FEC, epg) in grazing ewe weaners given 0, 85 or 170 g cottonseed meal pellet per head per day. FEC raised to the power 0.33 to nor malize data for statistical analysis. Faecal egg counts (FEC 0.33 Cumulative Live-weight Gains (kg) 12.0 10.0 8.0 6.0 4.0 2.0 0.0 0 2 4 6 8 10 12 14 16 18 29 43 52 Weeks after commencing supplementation 0g 85 g 170 g Figure 2 Cumulative live_weight gains, mean � SEM, of grazing ewe weaners given 0, 85 or 170 g cottonseed meal pellet per head per day. Recent Advances in Animal Nutrition in Australia, Volume 13 (2001)