The effects of stocking rate on liveweight gain of dorper wethers
An experiment on the effects of stocking rate on liveweight gain of Dorper wethers was conducted at Kabete) in Kenya from 23rd February to 13th July, 1981. The wethers were continuously grazed on natural pasture predominantly composed of Kikuyu grass (Pennisetum clandestinum). The experimental design was completely randomized. Each plot was set stocked with 3 wethers and there were 4 replicates. There were 3 sizes of plots, approximately 0.087, 0.0650 and 0.0433 hectares, corresponding to stocking rates of 34.6, 51.8 and 69.1 sheep per hectare. Results showed that the overall weight gain per head was 7.15, 5.54 and 3.8 kg at the low, medium and high stocking rates respectively. In the dry period (5weeks), the wethers lost a mean weight of 0.54 kg per head at the high and medium stocking rates. However, the wethers at the low stocking rate gained a mean weight of 0.54 kg per head. In the wet period (15 weeks), the wethers gained a mean weight of 6.67, 6.10 and 4.33 kg per head at the low medium and high stocking rates respectively. The differences in weight.changes between the different stocking rates for each period were only significantly different in the overall period, (P <0.05). An evaluation of the finishing stage showed that 50, 25 and 8% of the sheep at the low, medium and high stocking rates respectivel~ were ready for slaughter at the end of the experiment. The overall mean weight gain per hectare was 248.69, 288.14 and 262.00 kg at the low, medium and high stocking rates respectively. In the dry period, there was mean ~eight loss of 28.06 and 37.43 kg per hectare at the medium and high stocking rates respectively. However, there was mean weight gain of 18.75 kg at the low stocking rate. In the wet period, there was mean weight gain of 229.95, 319.84 and 299.43 kg per hectare at the low, medium and high stocking rates respectively. However, there were no significant differences in weight changes between stocking rates for any of the periods (P> 0.05). There was an increased emergence of herbs and forbs at the high stocking rate in the wet period. Changes in foliage cover showed that Kikuyu grass was tolerant to heavy grazing but there were signs of overgrazing at the high stocking rate. It was concluded that the medium stocking rate could be suitable but with caution because it was unable to finish off 80% of the sheep. Continuous rainfall was required if overgrazing had to be averted at the high stocking rate.