Feeding behaviour of Merino wethers under conditions similar to lot-feeding before live export

Abstract

Sheep from different farms (lines) in Western Australia were mixed in 3 experiments and lot-fed for 6-7 days as if for export. A marking method to identify sheep which eat from troughs was tested and used to examine the effects of feeding treatments on the proportion of sheep which eat during lot-feeding. Paint soaked sponges attached to troughs were used to monitor whether sheep ate. Positive linear relationships between liveweight change and paint marking score (R = 0.93, 0.93 and 0.94, in the 3 experiments) suggested that the technique was a reliable indicator of feed intake. Feeding treatments imposed were period of fasting before lot feeding (experiments 2 and 3); and diet type (hay pellets, hay/pellet mix) and trough location in the feedlot (experiment 3). There were large differences between lines in the percentage of sheep not marked. Values ¦ s.e. ranged from 1 ¦ 1 to 79 ¦ 3% for the 8 lines used in 3 experiments. In experiment 2, fasting for 48 h before lot-feeding resulted in more sheep (P<0.05) not marked (18 ¦ 7 3%) than did fasting for <12 h (9 ¦ 3%) and <24 h (8 ¦ 2%). In experiment 3, fasting for 96 h compared with 48 h resulted in fewer sheep marked daily when fed a hay-pellet mixture (75 ¦ 2 v. 93 ¦ 1%; P<0.001). When fed only pellets in experiment 3, the percentages of marked sheep increased with time (days). Feeding pellets only compared with a hay-pellet mixture resulted in fewer sheep marked daily (60 ¦ 2 v. 79 ¦ 2%; P<0.001) and more sheep not marked (11 ¦ 3 v. 3 ¦ 2%; P<0.05). If troughs were located in the centre of yards instead of on the fenceline, it took 2 rather than 7 days for the daily percentage of animals marked on the pellets only diet to exceed 80%. The central location also resulted in a mean of 78 ¦ 2% of sheep marked daily compared with 67 ¦ 2% for fenceline troughs (P<0.001) and a mean intake higher (P<0.01) by 0.13 ¦ 0.04 kg/wether.day. It was concluded that line of sheep, fasting, diet and trough location all had significant effects on feeding behaviour during lot feeding. Of these treatments, the greatest variation in feeding behaviour was associated with the line of sheep.