THE MALE EFFECT IN THE AUSTRALIAN CASHMERE GOAT .2. ROLE OF OLFACTORYCUES FROM THE MALE

Exposing seasonally anovulatory does to bucks may induce a synchronise d onset of fertile reproductive cycling, the 'male effect'. The role o f fleece and urine odours from the buck in mediating this effect was e xamined in three experiments. In each experiment, ovarian activity was assessed at laparoscopy on Days - 1, 5 and 10 or 11 after the applica tion of treatments. In Experiment 1 (April), more 18-month-old nullipa rous anovulatory does ovulated during 11 days of exposure to two bucks (18/18) than after continued isolation from bucks (0/18), wearing emp ty face masks (2/19), wearing face masks containing buck fleece (1/17) . or wearing face masks containing a chloroform/methanol extract of bu ck 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 s exual 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 o f does ovulating after exposure to bucks, buck fleece sprayed with uri ne, or to continued isolation from bucks was 7/29, 2/30 and 1/26, resp ectively. 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 Experime nt 3 (March) more anovulatory multiparous does ovulated during 10 days of continuous exposure to bucks (18/19) than during 10 days continuou s 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 spraye d onto the bag of fleece, and onto each doe's muzzle, daily. The effec t of wearing empty masks for 16 h day-1 on the response to bucks was e quivocal, with significant heterogeneity between replicates (9/10 and 3/10 does ovulating). Amongst does ovulating by Day 5, more of those e xposed to buck odours lapsed into an anovulatory state by Day 10, comp ared with those exposed to bucks (10/15 vs. 2/27; P < 0.001). We concl ude that: (a) exposure to buck fleece alone may induce an ovulatory re sponse 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 n ot enhanced by the addition of buck urine; (d) the intensity and durat ion of exposure to buck stimuli influences the ovulatory response obta ined. Overall the data suggest that the male effect in these goats is not a simple reflex response to olfactory cues but rather a complex re sponse involving the integration of a range of exteroceptive stimuli f rom the buck.