The value of cereal straw in drought rations for lot fed ewes.

Abstract

Proc. Aust. Soc. Anim. Prod. Vol. 18 THE VALUE OF CEREAL STRAW IN DROUGHT RATIONS FOR LOT FED EWES B.L, ASHTON* and A. E. KING* In droughts, sheep are often fed rations low in fibre because hay becomes scarce and expensive. Straw, which at times is abundant, could be used in place of hay. The aim was to compare barley straw with oaten hay as the roughage in feedlot drought rations with barley grain as the major source of energy and protein. Straw was fed at 40% higher rate than hay because it was assumed that straw could be obtained for 70% of the price of hay. Two hundred mixed age S.A. Merino ewes were put into a feedlot in November 1988 for 33 days. The sheep were then allocated by age and weight to five equal Over two weeks the groups. The average fasted live weight was 43.0 kg. rations were changed from oat grain to those shown in Table 1. Over the following 11 weeks the sheep were fed twice weekly, grain and roughages at the same time. Salt and finely ground limestone were added to the grain at 1% each. The barley grain contained 12.5 MJ of metabolisable energy (ME) per kg (of dry matter) and 12.4% crude protein (CP), The oaten hay had 8.8 XJ/kg of ME and 8.5% CP. The straw was Galleon barley tailings, baled directly behind the header without slashing. It contained 8.0 MJ/kg of ME and 2.6% CP. Table 1 Treatment rations and sheep responses after 13 weeks Sheep that lost more than 7 kg of live weight during the experiment were termed poor doers (see Table 1). The liveweight change (measured 72 h after feeding) in treatments 1 and 3 was of normal distribution, however the variance was greater than for treatments 4 and 5. This could have been because some sheep regularly missed out on their share of hay, as the hay was eaten quickly. The straw was eaten less quickly although it was all eaten in less than 24 hours. The sheep took more than 24 hours to eat the grain. There were no differences in fleece weight at shearing, tender wool or in death rate between poor doers and other sheep. At shearing in April, the wool, bulked from all sheep, was 56 N/ktex breaking strength and there were 2.5% tender fleeces. The wool from all groups was satisfactory. The average death rate of the sheep to shearing was 2.5%. Unexpected ME values for barley and straw resulted in rations of unequal ME. The ME for the barley straw was high. However, five samples of similar barley straw, baled by farmers on Eyre Peninsula averaged 7 -5 W/kg of ME, showing that the straw used in this trial was not uncommon. Theresults of the trial confirmed that straw can be more than 70% of the-feed value of oaten hay. There were less poor doers, and sheep lost less live weight, on rations containing straw than on rations containing hay. * Department of Agriculture, P-0. Box 1783, Port Lincoln, S.A. 449 5606.