High ME silages as an alternative feed source for the Australian feedlot industry

Summary

This project has demonstrated: That high quality silage diets could sustain live-weight gains in the range of 0.8 to 1.1 kg per day when fed as a sole diet to yearling steers. High silage - low grain diets gave better net returns per head than high grain diets. Carcases suitable for domestic trade were produced from steers on all diets (it took a little longer to finish silage only steers). There were no adverse affects of silage feeding on fat colour, meat colour, marbling or the physical properties of the meat associated with tenderness.

These findings have particular ramifications for the feedlot sector as they indicate that high quality silages (> 9.5 MJ/Kg DM) have the ability to replace a certain amount of grain in feedlot rations. This must have direct financial implications especially during periods of high grain prices. Silage research for the beef industry has been conducted in NSW, WA and Victoria. At the Agricultural Research Institute Wagga Wagga, a wide range of silage production and utilisation issues have been studied, including the composition of silage parent materials, cereal and legume crops, the production of silage from sub-clover based pastures, and other legumes, and silage production from maize, forage sorghums and millets etc. Beef cattle work at Bunbury in Western Australia has focused on the use of pasture silage plus grain supplements to finish cattle. The superiority of silage compared to hay made from the same pasture has been clearly demonstrated. In Victoria in recent years cattle have been successfully fed various maize silage supplements. The role of silage fed as a supplement to pasture in finishing systems for steers destined for the Japanese Ox market has been studied at Hamilton. There has been a deal of research on silage in the dairy industry carried out particularly in New South Wales and Victoria, which has important implications for the beef industry. A substantial research effort has also been put into the production and nutritive value of maize silage in both States. New South Wales has focused on the quality of the parent forage for silage production, with emphasis on maize and Kikuyu grass.

It can be expected that the agronomic studies and plant breeding programs carried out here on maize will be of particular importance to the feedlot industry. Silage research in the dairy industry has been carried out in Victoria since the late 1970s where emphasis is on the production of pasture silages examining the degree of wilting for silage production along with silage chop lengths. The development of the round bale silage system, including optimum bale density, has been carried out at Ellinbank. Maize silage research has been conducted at Kyabram examining the agronomy and management of irrigated maize crops and the use of this silage for backgrounding activities in the beef industry is being undertaken there. Silage produced from cereal crops and annual pasture is being used in lamb finishing diets in Western Australia while the MRC are about to finance further research under the Lamb Consistency Key Program in NSW into production from lambs on silage diets.

There is no doubt that the Australian silage research programs have demonstrated that cattle live weight gain in the range of 0.9-1.1 kg/day can be achieved feeding silage (ME ?9.5MJ/kg DM) alone and these gains can be increased by the addition of grain and protein supplements in the ration. Work with maize silage has been carried out both with dairy and beef cattle showing that it has much to offer as high metabolisable energy source. The potential of sorghum silage both grain and fodder varieties have been identified but further applied research needs to be carried out to select those varieties which have the greatest potential to produce under grainfed conditions in the feedlot regions of Northern NSW and south-east Queensland.