The male effect in the Australian cashmere goat. 2. Role of olfactory cues from the male

• Published in: Animal reproduction science Vol. 32; no. 1; pp. 55 - 67
• Main Authors: Walkden-Brown, S.W., Restall, B.J., Henniawati
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.07.1993
• Subjects: CAPRIN; CAPRINOS; GOATS; MACHO; MALE; MALES; OLFACCION; OLFACTION
• ISSN: 0378-4320; 1873-2232
• DOI: 10.1016/0378-4320(93)90057-X

Exposing seasonally anovulatory does to bucks may induce a synchronised onset of fertile reproductive cycling, the ‘male effect’. The role of fleece and urine odours from the buck in mediating this effect was examined in three experiments. In each experiment, ovarian activity was assessed at laparoscopy on Days −1, 5 and 10 or 11 after the application of treatments. In Experiment 1 (April), more 18-month-old nulliparous anovulatory does ovulated during 11 days of exposure to two bucks ( 18 18 ) than after continued isolation from bucks ( 0 18 ), wearing empty face masks (2/19), wearing face masks containing buck fleece (1/17), or wearing face masks containing a chloroform/methanol extract of buck fleece (3/17) ( P<0.001). Face masks were applied for 6 hr on Days 0 and 1 and for 2 hr on Days 2–8. In Experiment 2 (March), previous sexual experience did not influence the ovulatory response of 30-month-old nulliparous does to 10 days of intermittent exposure (16 h day −1) to bucks or buck fleece and urine in a mask. Overall, the proportion of does ovulating after exposure to bucks, buck fleece sprayed with urine, or to continued isolation from bucks was 7 29 , 2 30 and 1 26 , respectively. More does ovulated when allowed to run with two bucks for 16 h day −1 than in the other treatments combined ( P<0.05). In Experiment 3 (March) more anovulatory multiparous does ovulated during 10 days of continuous exposure to bucks ( 18 19 ) than during 10 days continuous exposure to buck fleece ( 8 20 ) or buck fleece and urine ( 7 20 ) ( P<0.01). More does ovulated in each of these treatments than in isolated controls ( 1 20 ) ( P<0.05). Buck fleece was hung in a bag in the pen and was rubbed daily on each doe's muzzle. Fresh buck urine was sprayed onto the bag of fleece, and onto each doe's muzzle, daily. The effect of wearing empty masks for 16 h day −1 on the response to bucks was equivocal, with significant heterogeneity between replicates ( 9 10 and 3 10 does ovulating). Amongst does ovulating by Day 5, more of those exposed to buck odours lapsed into an anovulatory state by Day 10, compared with those exposed to bucks ( 10 15 vs. 2 27 ; P<0.001 ). We conclude that: (a) exposure to buck fleece alone may induce an ovulatory response in seasonally anovulatory does; (b) this response is attenuated in comparison with that induced by bucks, with fewer does ovulating, and fewer ovulating does going on to re-ovulate; (c) the response is not enhanced by the addition of buck urine; (d) the intensity and duration of exposure to buck stimuli influences the ovulatory response obtained. Overall the data suggest that the male effect in these goats is not a simple reflex response to olfactory cues but rather a complex response involving the integration of a range of exteroceptive stimuli from the buck.