Arena behaviour of ewes selected for superior mothering ability differs from that of unselected ewes

Abstract

As part of a study searching for criteria for the genetic improvement of maternal ability, behavioural parameters were measured in ewes from two flocks, one selected for maternal ability (Fertility Flock), the other unselected (Random Flock). Behaviour was measured in an open-field test prior to mating in 1990 and in an arena test prior to mating in 1990 and 1991, and prior to lambing in 1991. The open-field test consisted of placing the ewes in an enclosed field measuring 16 m × 16 m for a period of 5 min. The field was divided into 16 squares each measuring 4 m × 4 m. The following measures were made: number of squares entered, whether or not the ewe bleated, urinated or defaecated and the number of bleats. The arena test consisted of placing the ewes in an enclosed arena measuring 3 m × 13 m; at one end of the arena there was a pen of sheep, in front of which sat a person. The floor of the arena was marked into 39 squares each measuring 1 m × 1 m. The test lasted 10 min and the following parameters were derived by recording the square in which the animal was located every 15 s; minimum and maximum distance from the person, mean distance from the person and distance travelled. The number of bleats was also recorded for each ewe, as well as whether or not she bleated, urinated or defaecated. There were no differences between the two flocks in any of the parameters measured in the open-field test. However, on all three occasions, there were differences between the two flocks in the total distance travelled and the number of bleats. The coefficients of repeatability of these two parameters, as measured by the intra-class coefficient of correlation, were 0.48 and 0.57 respectively. The results indicate that the arena test measures differences in the behaviour of ewes that differ in maternal ability and may therefore be of use in identifying ewes of superior mothering ability.