The effect of some pre-treatments on proteolysis during the ensiling of herbage

Two experiments were carried out to examine the nitrogenous changes occurring in herbage during harvesting and ensiling. In the first, ryegrass-clover was wilted rapidly in the laboratory (6 h) and in the field under good (48 h) and poor (48 h and 144 h) weather conditions. Protein breakdown and ammonia formation were negligible in herbage wilted rapidly and it was only when the crop was exposed to a prolonged wilt in humid conditions that appreciable proteolysis occurred. In the second experiment ryegrass-clover was ensiled in laboratory silos after treatment with varying levels of formic and sulphuric acids. An additional treatment included herbage inoculated with a mixture of lactic acid bacteria and glucose. The silos were opened after 4 and 50 d and samples were analysed for protein-N, ammonia-N, water-soluble carbohydrates and organic acids. There was a high negative correlation between level of addition of either acid and the degree of proteolysis and deamination. Even at the highest levels of formic acid (7·7 g per kg) and sulphuric acid (4·0 g per kg) additions, however, about 45% of the original herbage protein was degraded after 50 d in the silo. The inoculum treatment was also effective in reducing proteolysis, the effect after 50 d being comparable with formic acid applied at a rate of 4·1 g per kg.     

The digestibility of diets containing processed dried lucerne by sheep and cows

A series of trials was conducted to compare the digestibility of organic matter in castrated male sheep and non-lactating and lactating cows given diets containing lucerne cobs. Similar digestibility coefficients were determined when sheep and non-lactating cows were given hay and lucerne cobs, but lactating cows digested diets of hay, lucerne cobs and concentrates less well than sheep. It is concluded that if sheep are used in digestibility trials with diets containing processed lucerne and concentrates intended for milking cows, appreciable errors of prediction of digestibility of organic matter may arise.