Abstract:
Proc, Aust. Soc. Anim. Prod. Vol. 18 LIVEWEIGHT GAIN IN MERINO WETHERS FED TWICE WEEKLY ON A BARLEY SUPPLEMENT TREATED WITH VIRGINIAMYCIN S.I. GODFREY*, P.J. MURRAY* and J.B. ROWE* Wethers grazing cereal stubbles have shown little response in liveweight gain over the first 45 days of feeding when supplemented with barley grain (Rowe et al. 1989). The experiment reported here was designed to measure liveweight gain and feed intake in penned sheep fed a wheat chaff ration supplemented The performance of these animals was compared with twice weekly with barley. other groups supplemented with barley plus virginiamycin (VM, 40 g/tonne) or lupins. Merino wethers, 18 months of age and 35 kg live weight, were divided into four groups of 17 and penned individually. All sheep were fed wheat chaff twice daily ad libitum. Supplements were fed twice weekly at the equivalent of 200 g/day to thr ee groups with the fourth group receiving chaff only. Table 1 Mean liveweight gain (g/d), chaff intake (g/d) and feed conversion (kg supplement/kg gain above sheep fed chaff alone) measured in sheep fed wheat chaff with various supplements Following the introductory period, weeks 1-3, liveweight change was linear between weeks 4-8 and between weeks 8-13. These two periods were considered separately. Liveweight change and chaff intakes for each treatment group in each period were compared using analysis of variance. Least significant differences were used to compare treatment means if the variance ratio test comparing all treatment means was significant (PxO.05). Iiveweight gain during weeks 4-8 for sheep supplemented with barley twice weekly did not differ from animals fed chaff only (P~0.05). Sheep supplemented with lupins and barley plus VM had a greater liveweight gain (P<O.Ol, P<O.O5 respectively) compared to sheep fed chaff only or chaff supplemented with barley. Intake of chaff for sheep supplemented with barley was less than for sheep supplemented with lupins (P<O.Ol) or barley plus VM (PxO.05). Use of supplement was less efficient for animals supplemented with barley during weeks 4-8, The improved liveweight gain after week 8 in sheep supplemented with barley indicates an adaptation of rumen micro organisms to the supplementary feeding regime. VM increased liveweight gain, feed intake and feed conversion during the initial 8 weeks of feeding the barley supplement by altering rumen fermentation. The addition of VM therefore appears to have the potential to make barley grain an alternative to lupins for short term feeding of ruminants where digestible energy is the primary limiting nutrient. ROWE, J-B., BROWN, G., RALPH, I-G., Aust. J. Exp. Agric. 29: 29. FERGUSON, J. and WALLACE, J-F.(1989). * Sheep and Wool Branch, Dept Agriculture, South Perth, W.A. 6151. 480
