The influence of degree of adaptation to tether-housing by sows in relation to behaviour and energy metabolism

Abstract

In response to tethering, many sows develop seemingly non-functional repetitive behaviour (stereotypies), which may be performed for several hours in a day.The quality and quantity of activity performed by sows with different degrees of adaptation to tethering was studied in relation to energy expenditure. Three groups of five sows were recognized: (1) High, sows which showed a high incidence of stereotyped activity after prolonged tethering; (2) T/Low, sows with limited experience of tethers; and (3) G/Low, the same sows as in group 2 after regrouping.High sows were about three times more active than T/Low sows: the proportions of time involved in 24 h were 0·35 and 0·13 respectively. Most of the former sows' activity was in the form of sterotypies. The activity level of the G/Low sows was between that of the two tether treatments (proportionately 0·17 of 24 h). Both tethered treatments spent proportionately about 0·05 of 24 h in using drinkers compared with proportionately less than 0·02 of the time for the G/Low sows.High sows produced proportionately 0·36 more heat than T/Low sows during the 12-h light period in each day. During this period, proportionately 0·40 and 0·20 of heat production from High and T/Low sows was associated with activity. The diurnal activity of the G/Low sows was associated with proportionately 0·24 of heat production.Stereotypies and excessive drinker use accounted for proportionately 0·86, 0·52 and 0·24 of the activity of High, T/Low and G/Low sows. The proportions of metabolizable energy intake required for these activities were 0·23, 0·07 and 0·04 respectively for the three treatments. The study concludes that tethering is stressful when sows develop, and then indulge in frequent coping behavioural patterns which increase metabolic rate.