Response of Ingestive Behaviour of Sheep to Restricted Time at Pasture and Indoor Feeding

This study was conducted to investigate the response of ingestive behaviour of sheep to the restriction of time at pasture combined with indoor feeding.Thirty castrated male Ujumuqin lambs were randomly assigned to 5equal groups:(i)no grazing(0H;control),(ii)2hgrazing(2H),(iii)4hgrazing(4H),(iv)8hgrazing(8H),and(v)12hgrazing(12H).Behavioural activities of two lambs from each treatment were monitored daily by 2observers during the first 10 days of July,August and September(investigating periods),respectively.Observations of each group were conducted for a 2dperiod and daily observation time was 15 hfrom 06:00to 21:00throughout the whole investigating period.The results showed as follow:(1)Restrictions at pasture significantly affected animal behavioural pattern.With the time at grazing reduction,the proportion time spent grazing increased(P0.001),while the time spent resting and walking,and walking distance decreased significantly(P0.001).2Hand 4Htreatments had no time to rest during grazing.(2)Chewing rate was significantly affected by treatments(P=0.003).0Htreatment present the lowest chewing rate and 4H,8Hand 12 Htreatments present the highest,however,lambs in the 2Htreatment had a lower chewing rate than the 4H,8Hand 12 Htreatments.Biting rate tended to be affected by treatment(P=0.067),and lambs allocated to the 2Hand 4H treatments had higher biting rates(+3.6and +1.8bites·min-1)compared to the 12Htreatment(51bites·min-1).(3)Behavioural activities were significantly affected by the season.The time spent on grazing in July was more than(P0.001)that in August and September.A significant(P0.001)reduction in walking distance was observed in 8Hand 12 Htreatments from July to September,but no difference was found between 2Hand 4Htreatments.Lambs decreased(P0.001)their biting rates and increased(P0.001)their chewing rates as the season progressed.Animals restricted access of 4hper day at pasture has the strong ability to adapt their behavioural activity through increasing the proportion of grazing time,decreasing the proportion of resting time,and accelerating the chewing rate to improve grazing efficiency in compensation for the reduced access time to pasture.