Abstract:
BYPASS PROTEIN RESEARCH IN NORTH-EAST VICTORIA G.H. SMITH* On averzjge, the growing season in Northern Victoria extends from . 'May to November which means that dry forage is the major feed available to grazing ruminants, for the balance of the year (except in the nonirrigated areas) a This base feed of either dry, annual pasture or crop stubbles provides little better than stock maintenance. Livestock production in such areas could be considerably improved if higher levels of performance (growth, reproduction, lactation) were possible on this feedHence, one line of research at the Rutherglen Research Institute is examining the potential of bypass protein supplements to boost the performance of' ruminants grazing dry feed* 'An initial experiment examined the effect of four protein supplements on the consumption of poor quality roughage by lambs over a seven-week period. Twenty, cross-bred lambs of mixed sex `and aboutsixa conditioning ', months old were penned individually indoors. . After .period of four-weeks, the lambs were randomly allocated to five treatments, All lambs were provided withanad lib. supply of hammer-milled, poor quality roughage (mature, dry annual pasture of 43% digestible organic matter, 7% crude protein and 40% crude fibre). The roughage was *withdrawn for about 15 minutes each day while the protein supplements were fed and consumed. The same quantity of supplementary, crude protein was fed in each treatment. Individual intakes of'the roughage and liveweights of the lambs were measured weekly. TABLE 1 Roughage consumption and liveweight changes of lambs '. That experiment identified the protected portein nuts as effective supplement in stimulating appetite for the dry pasture promoting growth. A subsequent experiment examined the response cattle fed this supplement while,grazing typical, dry forage over summer of 1980/81. the most and of young the Two groups of 24 weaner steers (Polled Hereford, about 250 kg liveweight, 12 months old) were stocked on either oaten stubble or dry, annual pasturein late December, 1980. The stocking rate was such that the availability of dry feed would not become limiting'over the experimental period. * Department of Agriculture, Rutherglen Research Institute, Rutherglen 3685- 4A * The bypass protein supplement was fed daily at IeveLs of 0, 200, 400, 800 and 1000 q- per head per day - there being four beasts per treatment. The daily proceudre involved yarding the cattle into a small enclosure adjacent to their paddock of dry feed and feeding the supplement to each b.east individu&lly in stalls. The cattle were weighed after a 24 hour fast at the start and end of the experimental feeding period and also weighed full fortnightly during the experiment. . After a conditioning period, the experimental feeding began in mid January and continued for 70 days. To. some extent, the experiment was frustrated by above average summer rain (January 63 mm, (37'mm average); February 85 mm (38. mm average)) which caused germination in February. To counter this, the oaten stubble paddock was sprayed to kill the germination, but this was not practical in the dry pasture paddock. Hence, the results from the steers grazing oaten stubble are probably a true indication of relative performance in that dry feed. But for the pasture treatments, the results at 70 days were no doubt consider-. ably influenced by the green .feed available after about mid-February. Therefore results after six weeks are also presented for those treatments. TABLE 2, Growth 0f.steer.s grazing oaten stubble or dry pasture and supplemented with bypass protein. Under the grazing conditions of this experiment, oaten stubble provided a more productive base feed than did dry annual pasture. The bypass protein supplement appeared to 'be effective in stimulating appetite for dry feed because the response to the supplementary feeding were greater than could be accounted forby the supplement aloneThe results suggest that if a producer is not satisfied with the perfo.rmance of stock graiing dry feed, then .bypass ,protein should be an effective. supplement to feed, Appropriate stock to supplement might . include: weaner sheep, yearling bulis and summer calving cows.