A study on the grazing ability and the behaviour of sheep on tethering

Abstract

The grazing ability and the behaviour of sheep on tethering were observed for the purpose of investigating the potential of sheep for weed control.
One relatively submissive type ewe and another relatively nervous type ewe were used for tethering. Ewes were tethered on 2 m of rope each a short distance apart using dog collars to keep them safe from twining each other's rope. Tethering started at 10 : 00 and finished at 15 : 00, and was repeated six times. Ewes were kept in a pen from the evening of the day before the tethering, given only water. The behaviour of sheep on tethering was recorded by a video-recording system. Grazing behaviour, drinking behaviour, resting behaviour, and investigative behaviour were investigated. A previous measurement was done on the amount of feces and urine of sheep during a five-hour span using three ewes with paper diapers, and repeating the procedure twice while pasturing.The amount of grazing during tethering was estimated from the body weight increase and the amount of feces and urine during the five hour time period.
Sheep 1 and sheep 2 showed 3.35-4.57 hours and 3.03-4.55 hours of grazing behaviour, respectively. The means of grazing bout duration of sheep 2 were 0.6-2.1 minutes, showing a tendency to be shorter than that of sheep 1. The resting behaviour count of sheep 1 (the relatively submissive type) was observed to be 1-3 times for each observation except for the fourth observation. However, resting frequency of sheep 2 (the relatively nervous type) was just twice only on the second observation, with no rests observed any other time. From the first to the fifth observation, sheep 1 and sheep 2 showed cautious and investigative behaviour 0.4-6.6 times and 6.6-27.8 times per hour, respectively. The body weight increases during five hours' tethering were 3.0-4.8 kg for sheep 1 and 1.2-6.8 kg for sheep 2. During the first three observations, sheep 2 showed only a little body weight increase. Both ewes grazed enough on the fourth observation and the estimated amounts of grazing were 5.5 kg for sheep 1 and 7.5 kg for sheep 2, respectively. Sheep 2 (the relatively nervous type) seems to have become accustomed to tethering and to have grazed enough since the fourth observation. Although it was somewhat noisy on the sixth observation, the estimated amount of grazing for sheep 2 was 3.7 kg.
These results showed the utility of tethering sheep for weed control, demonstrating that sheep became accustomed to a tethered situation faster by tethering two sheep a short distance apart, although there were some differences on the adaptability to tethering. They grazed well as much as 4 kg during five hours' tethering in the daytime.