Anhydrous ammonia-treated cereal straw for animal feeding. Some results from the Mediterranean area

Abstract

Samples of barley straw, maize stover (1980), wheat straw and maize stover (1981), untreated and treated with 35 g anhydrous ammonia (NH 3)/kg were studied during two successive years (1980–1981) (Trial 1). The ammonia treatment increased their crude protein (CP) content by 52, 144, 47 and 76%, respectively. The organic matter digestibility by wether sheep increased by 10, 19, 19 and 15% and straw voluntary intake increased by 23, 33, 19 and 23%, respectively. In Trial 2, 6 t of barley straw was treated with anhydrous NH 3, 3 t in summer (STS) (38°C ambient temperature) and 3 t in autumn (ATS) (7°C). CP content was 83% higher in the STS than in the ATS. The organic matter digestibility and the quantity of straw consumed by wether sheep were higher ( P < 0.05) in the STS than in the ATS. No differences were found in the amount of retained nitrogen. In Trial 3, the effect of the NH 3 treatment in a commercial oven (24 h at 90°C) on barley straw was studied. As the original straw was of good quality, the effect of the treatment was only a moderate increase (14%) in the ingested digestible organic matter ( P < 0.10), and an increase of 64% in CP content. The amount of nitrogen lost in faeces was higher ( P < 0.01) with treated roughage diets than with untreated diets, but the loss of nitrogen in urine was lower ( P < 0.01). Finally, in Trial 4, the effect of stack size (3.1, 4.2 and 5.0 t of straw) on treatment homogeneity was studied. No differences in CP content or dry matter digestibility in vitro were found between stacks or within stacks of different sizes.