Photoperiod-Treatment in Mediterranean Bucks Can Improve the Reproductive Performance of the Male Effect Depending on the Extent of Their Seasonality

Abstract

This study examines the effectiveness of the photoperiod treatment (extra light for 88 days) to render the bucks sexually active during the seasonal anoestrous in order to induce a male effect, depending on the reproductive seasonality of the breed of the bucks used. In April, 57 anoestrous Blanca Andaluza does were distributed into four groups with three males each: 13 were exposed to control Murciano–Granadina bucks (lower seasonality); 15 were exposed to photostimulated Murciano–Granadina bucks; 14 were exposed to control Blanca Andaluza bucks (higher seasonality), and 15 were exposed to photostimulated Blanca Andaluza bucks. After male introduction, the sexual behaviour of the bucks was assessed, and harness marks recorded doe oestrous behaviour. Ovulation was confirmed from plasma progesterone, and the ovulation rate was assessed by transrectal ultrasonography. Fecundity, fertility, prolificacy and productivity were also determined. All of the does in all of the groups showed ovulation. Interaction between both sources of variation was observed: the percentage of females showing oestrous (p < 0.01) and productivity (p < 0.05) was the lowest in the Blanca Andaluza control group (50% and 0.36 ± 0.17 goat kids born/female, respectively). In conclusion, photoperiod-treated bucks efficiently induce a male effect, but photostimulation could be more necessary for breeds with deep seasonality.

The High Testosterone Concentrations of the Bucks Used in the “Male Effect” Is Not a Prerequisite for Obtaining High Ovarian Activity in Goats from Mediterranean Latitudes

“…But, anestrous ewes triggered a reduced response [23,24]. However, in the present experiment and others performed by our group [18], we observed a similar response, suggesting that at Mediterranean latitudes or with the Spanish breeds used, the anestrous does can induce a rapid increase in testosterone concentration, observed just after buck introduction, more quickly than the estrous response of the females. These results suggest that the bucks isolated from the does are stimulated by them even when they are anestrous.…”

“…This breed has reduced seasonality. We have demonstrated that the photoperiod treatment is more effective when was applied to bucks of a breed with an intense seasonal anestrous, such as the Blanca Andaluza breed [18]. This fact could demonstrate that under Mediterranean conditions, the testosterone concentrations of the bucks when they are introduced to the does is not a primary factor in obtaining an adequate reproductive response.…”

“…However, our group has observed a very high ovarian activity in Mediterranean goats when non-photostimulated bucks are used. In those bucks, increased testosterone concentrations were observed following their introduction to the does [18].…”

Microbiota in Goat Buck Ejaculates Differs Between Breeding and Non-breeding Seasons

“…Murciano-Granadina is a Spanish goat breed that is well-adapted to Mediterranean environmental conditions. Previous studies have shown significant seasonal variation in semen quantity and quality, but we can consider that it is a breed with low reproductive seasonality (21,22,26,34). Although the males from this breed show a longer reaction time in spring (34), and plasma testosterone concentrations display a well-defined seasonal pattern (26,35), the quality of ejaculates is good all year long (21).…”

“…This center is located in the Spanish town of Segorbe (Castellón; coordinates 39.86 N, 0.50 W), which belongs to the Valencian Community (east Spain). This breed presents low reproductive seasonality, and its non-breeding season goes from February to May (26). The animals were housed in pens.…”