Effects of frequency of provision on the utilization of a treated barley supplement.

Abstract

Proc. Aust. Soc. Anim. Prod. Vol. 19 EFFECTS OF FREQUENCY OF PROVISION ON THE UTILIZATION OF A TREATED BARLEY SUPPLEMENT A. ROBAINA, B. J. HOSKING and R. M. DIXON School of Agriculture and Forestry, University of Melbourne, Parkville, Vic. 3052. Most studies with cereal grain supplements for ruminants involve daily feeding, although differences associated with frequency of offering supplements occur (Egan et al. 1986). The present study examined the effect of intermittent feeding of a grain supplement on the intake and digestion of a roughage diet by young sheep. Grain was treated with virginiamycin to encourage rapid adaptation to the barley supplement (Godfrey et al. 1990). Thirty 18-month-old wether sheep were allocated to dietary treatments (n = 6) consisting of chaffed oaten hay (0.8%N) fed ad libitum on its own (NIL) or supplemented with the equivalent of 200 g/day of a barley supplement fed daily (Tl) and at intervals of 3 (T3), 6 (T6) or 12 days (T12). The barley was treated with an antibiotic (virginiamycin, 4Og/t; Smith-Kline Beecham). A 40% (w/v) solution of urea-ammonium sulfate was added to the grain at the rate of 30 niL/200 g immediately prior to feeding. Feed intake was recorded daily. Sheep were weighed at 12-day intervals over the 36-day experimental period. Wool growth was measured from dye-bands applied 3 days before treatments commenced and at the end of the experiment. Half the sheep in each treatment were fistulated in the rumen. Nylon bags containing chaff or barley were suspended in the rumen for 24-h periods on 3 successive days after offering grain supplements (days 15-18) in T3, T6 and T12 treatments and loss of dry matter from the bags was recorded. Rumen ammonia concentration and pH were also measured. Table 1. Feed intake, liveweight change (LWC), wool growth and 24 h dry matter loss from nylon bags in the rumen of sheep fed treated-barley supplements at intervals from l-12 days There were no differences in chaff intake between treatments (P > 0.05). Supplement feeding increased total intake and reduced the rate of liveweight loss. There were no significant differences in liveweight change or wool growth between supplement treatments, although the greatest responses tended to be found with daily supplementation (Tl) and the least with T6. Sheep fed treatments Tl, T3 and T6 consumed all the grain offered within 24 h. Sheep in the T12 treatment consumed the supplement gradually over days l-6 after feeding. Frequent supplementation (Tl and T3) increased 24 h chaff DM loss (P < 0.01) over the NIL treatment. Less frequent supplementation (T6 and T12) resulted in reduced chaff DM loss. The results indicate barley grain treated with virginiamycin and urea/ammonium sulfate can be fed at intervals of up to 12 days without the high rates of substitution or acidosis commonly associated with cereal supplementation. The small differences in liveweight change and wool growth between barley treatments suggested that feeding frequency did not markedly affect supplement use at this level of inclusion in the diet. EGAN, A. R., FREDERICK, F. and DIXON, R. M. (1986). In ` Ruminant Feeding Systems Utilizing Fibrous Agricultural Residues.' (Ed. R. M. Dixon.) pp. 69-83. (IDP: Canberra). GODFREY, S., MURRAY, P. J. and ROWE, J. B. (1990). Proc. Aust. Sot. Anim. Prod. 18: 480. 303