Efficiency of the male effect with photostimulated bucks does not depend on their familiarity with goats.

In ewes, the ovulatory response of females exposed to familiar rams is lower than the response of those exposed to novel ones. In goats, males rendered sexually active by exposure to long days are more efficient to induce ovulation in seasonal anestrous females than untreated males. Two experiments were conducted to determine 1) whether male goats remain familiar to females after 45days of separation; and 2) whether photostimulated males are able to stimulate the sexual activity of females, independently of their familiarity with them. In Experiment 1, three groups of goats (n=10 goats per group) were put in contact with males (n=2 per group) during 10days in November (familiarization period). These males were called familiar males. After 15, 30 and 45days of separation from the males, females of each group were exposed to familiar or novel males during 10min. In each test, goats in contact with novel males displayed more distress bleats, escapes, head butts, and sniffing than those in contact with familiar males (P<0.05). In Experiment 2, we used sexually inactive (n=4 control males), and sexually active males (n=4 photostimulated males). In February, two groups of goats (n=50 each) were put in contact with control or photostimulated males (n=2 each) during 10days ("familiar" control or photostimulated male, respectively). After 45days of separation from the males, both groups of females were further divided into two groups (n=25 goats per group). In April, two groups were re-exposed to "familiar" control or "familiar" photostimulated males (n=2 per group), whereas the other two groups were exposed to "novel" control or "novel" photostimulated males (n=2 per group). The photostimulated males displayed a higher level of sexual behavior than the controls. The proportion of goats that ovulated and displayed estrus was higher when exposed to the photostimulated males than when exposed to control ones (≥80% vs. 0%; P<0.05). These proportions did not differ between groups exposed to familiar or novel photostimulated males (P>0.05). We concluded that after 45days of separation, males are still familiar to females. The photostimulated males are able to induce the sexual activity of seasonally anestrous goats independently of their familiarity with them.

The physiological consequences of crib-biting in horses in response to an ACTH challenge test.

Stereotypies are repetitive and relatively invariant patterns of behavior, which are observed in a wide range of species in captivity. Stereotypic behavior occurs when environmental demands produce a physiological response that, if sustained for an extended period, exceeds the natural physiological regulatory capacity of the organism, particularly in situations that include unpredictability and uncontrollability. One hypothesis is that stereotypic behavior functions to cope with stressful environments, but the existing evidence is contradictory. To address the coping hypothesis of stereotypies, we triggered physiological reactions in 22 horses affected by stereotypic behavior (crib-biters) and 21 non-crib-biters (controls), using an ACTH challenge test. Following administration of an ACTH injection, we measured saliva cortisol every 30 min and heart rate (HR) continuously for a period of 3h. We did not find any differences in HR or HR variability between the two groups, but crib-biters (Group CB) had significantly higher cortisol responses than controls (Group C; mean ± SD: CB, 5.84 ± 2.62 ng/ml, C, 4.76 ± 3.04 ng/ml). Moreover, crib-biters that did not perform the stereotypic behavior during the 3-hour test period (Group B) had significantly higher cortisol levels than controls, which was not the case of crib-biters showing stereotypic behavior (Group A) (B, 6.44 ± 2.38 ng/ml A, 5.58 ± 2.69 ng/ml). Our results suggest that crib-biting is a coping strategy that helps stereotypic individuals to reduce cortisol levels caused by stressful situations. We conclude that preventing stereotypic horses from crib-biting could be an inappropriate strategy to control this abnormal behavior, as it prevents individuals from coping with situations that they perceive as stressful.