When using photostimulated bucks to induce the male effect in female goats living at Mediterranean latitudes, a male: female ratio of 1:20 is optimum

Abstract

This study examines the reproductive response and reproductive performance of does subjected to the male effect at different male:female ratios when photostimulated males are used. One hundred and thirty does were distributed homogeneously into six groups with male:female ratios of either 1:30 (two repetitions of 30 females with one male each), 1:20 (20 females with one male), 1:15 (15 females with one male), 1:10 (20 females with two males), or 1:5 (15 females with three males). After the introduction of the males (all made sexually active by keeping them for three months under long days), oestrous activity was recorded daily by direct visual observation of the marks left by marking harnesses worn by the males. Ovulation was confirmed via the plasma progesterone concentration. Fecundity, fertility, prolificacy and productivity values were also determined. The 1:30 group returned the lowest percentage of does that ovulated and that showed oestrous activity; it also returned the lowest fecundity and fertility values. The highest values for all these variables were recorded for the 1:5–1:20 groups (with no significant difference between them). These results show that, under Mediterranean latitudes, the reproductive response, fecundity and fertility are diminished when the photostimulated male:female ratio is very low (1:30). The optimum ratio would appear to be around 1:20.

Keywords

• Goat
• male effect
• oestrous activity
• ovulation
• artificial photoperiod