Temperament and reproductive biology: emotional reactivity and reproduction in sheep

Abstract

Reproductive capacity is controlled by a large number of factors such as season, social interactions and metabolic status. However, the influence of emotional reactivity on reproductive success has not been intensively investigated in farm animals. In this review, we define emotion reactivity and the expression of its inter individual variability named temperament. We briefly describe our protocol to measure temperament in sheep and discuss the heritability of temperament traits. Using the results obtained from our flock of sheep selected for calm or nervous temperament, we illustrate how this selection affects the reproductive biology from changing the inexperienced ewe's response to the male effect to improving lamb survival and ovulation rate. We conclude that the mechanisms by which selection for temperament affects the different steps of the reproductive cycle are not yet understood but nevertheless this type of selection could have a great impact on reproduction efficiency of sheep and other domestic ruminants.

Exploration of the Hypothalamic-Pituitary-Adrenal Axis to Improve Animal Welfare by Means of Genetic Selection: Lessons from the South African Merino

“…This study indicated the role of the PVN to translate signals of emotional stress via the HPAA to increase or decrease cortisol levels accordingly [ 73 ]. Furthermore, the emotional reactivity (temperament) of sheep has been successfully used as selection criterion in breeding programmes to improve reproductive biology [ 92 ]. Selection for “calm” ewes increased lamb survival and maternal behaviour [ 77 ].…”

Calm Merino ewes have a higher ovulation rate and more multiple pregnancies than nervous ewes

“…The ewes of the selection lines have similar productive outcomes when not challenged by the environment or nutrition (Bickell et al, 2010a;Blache and Bickell, 2010;Hawken et al, 2012). When under sub-optimal conditions, the calm ewes perform better than the nervous ewes (Hawken et al, 2012).…”

“…In fact, the analysis showed that ewes in the calm line carried more foetuses (1.39, n = 472) compared with nervous ewes (1.29, n = 302). The calm ewes carried a higher proportion of twins, 35.4% compared with 14.6% for the nervous ewes (P < 0.001; Blache and Bickell, 2010).…”

“…In 1990, two different selection lines of Merino sheep were established for low and high behavioural reactivity (also called calm and nervous temperament, respectively) at the University of Western Australia (Murphy et al, 1994;Blache and Bickell, 2010). In the early years of the selection, low behavioural reactivity was more strongly correlated with improved maternal behaviour and greater lamb survival than in the high behavioural reactivity ewes (Murphy et al, 1994;Murphy, 1999).…”

“…In the early years of the selection, low behavioural reactivity was more strongly correlated with improved maternal behaviour and greater lamb survival than in the high behavioural reactivity ewes (Murphy et al, 1994;Murphy, 1999). After 10 to 13 years of selection, the differences in maternal behaviour and lamb survival between the two lines had dissipated (Bickell et al, 2010b), but breeding records of the two lines obtained over 4 years showed that 10% to 19% more lambs (to mated ewes) were weaned from the calm ewes than from the nervous ewes (Blache and Bickell, 2010). The higher reproductive success of the ewes of the calm line compared with those of the nervous line could be explained by diverse impacts of behavioural reactivity on the reproductive biology of each line (Blache and Bickell, 2010).…”