The preservation of a Nandi Setaria silage and its feeding value for dairy cows

Abstract

The process of vacuum ensilage of Setaria Sphacelata (cv. Nandi) (33 per cent DM ; 7 per cent soluble carbohydrates; 1.36 per cent M) was studied, and the resultant silage was evaluated chemically, in milk production trials with dairy cows and in digestion trials with dry cows. The silage was well preserved in a chemical sense (pH 4.5; lactic acid 1.7 per cent, volatile acids 1.2 per cent DM ; volatile bases 9.8 per cent total N) but, because of the structural rigidity of the harvested grass, air could not be completely excluded even from the polythene-covered vacuum stack. The temperature reached 43¦C in the first week of storage and considerable surface wastage occurred. The silage (DM digestibility 42 per cent, voluntary DM intake 81 g/kg0.75) was of poorer quality than the grass harvested (DM digestibility 54 per cent, voluntary DM intake 84 g/kg0.75) and, even by feeding concentrates, only a low level of milk production could be sustained in (mainly Jersey) cows in the 5th-9th months of lactation. In silage-fed cows given a protein supplement (cottonseed meal) milk production was lower (3.8 kg day-1) but fat content higher (5.4 per cent) than in those given an energy supplement (sorghum grain) or energy plus protein (4.7 kg day-1 and 4.9 per cent fat). When fed lucerne hay and given the same energy plus protein supplement, cows gave significantly more milk (5.7 kg day-1 and 4.6 per cent fat). The poor nutritive value of the silage is attributed to the nature and composition of the material ensiled rather than to any defect in the ensilage process itself, and may be a feature of most silage made from tropical grasses.