Effects of fertilizer and stocking rate on pasture and beef production from sown pastures in north Cape York Peninsula. 2. Beef production and its relation to blood, faecal and pasture measurements

Abstract

The animal production from two grass/legume pastures was measured over three years. The pastures were grazed at four stocking rates and annually received one of three maintenance rates of phosphorus fertilizer. The animals were given a phosphorus supplement at two rates. The grasses were either Brachiaria decumbens cv. Basilisk or Panicum maximum (common guinea grass) each sown with Stylosanthesguyanensis cv. Endeavour and Macroptilium atropurpureum cv. Siratro. The grasses had little effect on animal production although three Panicum pastures at higher stocking rates became overgrazed and required destocking during the experiment. Even though 73.5 kg ha-1 of phosphorus was used to establish the pastures, the maintenance rate of 40 kg ha-1 gave higher production than the 10 kg ha-1 rate in the first two years. In the third year, production was similar for each fertilizer rate. There was a concomitant rise in faecal phosphorus level with fertilizer rate but no such effect with blood inorganic phosphorus levels. Over the three years of the experiment the liveweight gain per hectare was similar (mean of 0.54 kg per day) at 1.7 and 1.9 beasts ha-1 but was significantly less at lighter stocking rates. In the last two years stocking rate did not significantly affect liveweight gain per head. At the highest stocking rate, gains were greater during the wet season and losses greater during the dry season than those at the lowest stocking rate. The phosphorus supplement did not affect animal production but increased blood inorgainc phosphorus levels. The relationships of animal production with blood and faecal compositions and with the pasture measurements described in a previous paper are discussed.