The nutritional value of intact seed pods of Townsville lucerne (Stylosanthes humilis)

Abstract

Two experiments were done on the digestibility of Townsville lucerne seed with pod by sheep in metabolism cages. In one experiment, all sheep were fed the same amount (454 g dry matter seed with pod each day) and mean dry matter digestibility was 58.6 ¦ 3.4 per cent. In the other, three different levels of seed with pod were fed, and mean organic matter digestibility ranged from 54.0 ¦ 1.2 to 68.3 4 1.8 per cent, but digestibility was not significantly inversely related to mean organic matter intake which ranged from 438 ¦ 69 to 335 & 10 g/day (P>0.05). The seed with pod contained, as per cent of dry matter, 5.54 per cent nitrogen, 0.36 per cent phosphorus, 0.30 per cent sulphur, and 0.88 per cent calcium. The sheep were in positive nitrogen balance, but in negative phosphorus balance. Between 8 and 14 per cent of actual seed consumed was defaecated unbroken. Up to 25 per cent of the faecal organic matter was unbroken seed, which was of high germination capacity (76 per cent). Amount of defaecated seed (P<0.001) and the defaecated seed as a percentage of faecal organic matter (P<0.02) were linearly related to amount of actual seed consumed. Factors affecting the amount of undamaged seed in the faeces and a possible technique for assessing seed consumption by grazing animals are discussed.