Induction of sexual activity of male creole goats in subtropical northern Mexico using long days and melatonin.

One experiment was conducted to determine whether the treatment with artificial long days and exogenous melatonin can induce reproductive activity during spring (seasonal anoestrus) in Mediterranean goats that are in daily contact with bucks and whether this treatment causes a variation in the reactivation of the reproductive activity in the normal breeding season. The experiment started on 4 November 2005 and finished on 27 October 2006. Thirty-four adult and barren does were used, distributed into two groups balanced according to their live weight (LW) and body condition score (BCS). Seventeen females were exposed to long days (16 h of light/day) from 14 November 2005 to 20 February 2006. On 20 February, they received one s.c. melatonin implant (LD-M group) and were exposed to natural photoperiodic changes in an open shed. The other females during the experiment were placed in an open shed under natural photoperiod and remained as the control group (C group). The C and LD-M groups were keeping in contact with males during the whole experiment. During the experiment, the LW, BCS and plasma progesterone concentrations were measured weekly, oestrous activity was tested daily using entire aproned bucks, and ovulation rate was evaluated by laparoscopy 7 days after positive identification of the oestrus. A clear treatment–time interaction was observed for plasma progesterone concentrations ( P,0.001), with a period of high progesterone concentrations during the natural seasonal anoestrus in the LD-M group. Although 94.1% of females in the LD-M group presented ovarian activity during this period, no female in group C did. Resumption of ovarian activity in the subsequent natural breeding season was 2 weeks later in the LD-M group in comparison with group C ( P,0.05). We can conclude that in Mediterranean goat breeding systems, when females are in daily contact with bucks, the treatment with 3 months of long days and melatonin implant at the end of the light photoperiodic treatment can induce ovarian and oestrous activity during the seasonal anoestrus. Finally, this treatment causes a short delay in the subsequent reactivation of ovarian activity in the natural breeding season

Section: Discussionsupporting

confidence: 87%

Artificial long days in addition to exogenous melatonin and daily contact with bucks stimulate the ovarian and oestrous activity in Mediterranean goat females

Zarazaga

Gatica

Celi

et al. 2011

“…Recently, we found that treatment by long days followed by melatonin implants stimulates some sexual activity in Alpine bucks under temperate latitude (Delgadillo et al, unpublished results). However, the responses of Alpine males in terms of testosterone and sexual behavior were not as strong as those observed in the subtropics in this study or with local Mexican bucks (Flores et al, 2000;Delgadillo et al, 2001). The ovarian response of anestrous light-untreated Alpine does exposed to these Alpine long days and melatonintreated bucks was limited (50% of does ovulating; Delgadillo et al, unpublished results).…”

Section: Discussioncontrasting

confidence: 56%

“…Therefore, artificial photoperiod treatments could be used to modify the reproductive seasonality in males and females. Indeed, exposure of animals to 2 or 3 months of long -E-mail: joaldesa@yahoo.com days followed by either short days or a melatonin treatment, a hormone that mimics the effects of short days, stimulates their sexual activity during the non-breeding season (Donovan et al, 1994;Delgadillo et al, 2001;Chemineau et al, 2007). Another possibility to stimulate the sexual activity in anestrous females is the use of socio-sexual relationships.…”

Section: Introductionmentioning

confidence: 99%

Stimulation of reproductive activity in anovulatory Alpine goats exposed to bucks treated only with artificially long days

Delgadillo

Vélez

2010

Two experiments were conducted in a subtropical latitude to determine the response of Alpine male goats to a treatment with artificially long days (experiment 1), and the response of anovulatory lactating Alpine does exposed to males treated only with artificially long days (experiment 2). In experiment 1, one group of males was kept under natural photoperiod ( n 5 4) while another was exposed to 2.5 months of artificially long days (16 h of light/day) from 1 December ( n 5 4). Plasma testosterone concentrations were determined weekly. Intensity of odor of males was determined every 2 weeks. Sexual behavior of bucks was observed during 3 days about 90 days after the end of the long day treatment. A treatment-by-time interaction was detected for testosterone secretion ( P , 0.001). In control males, low plasma concentrations of testosterone were observed from March to June. In contrast, in long-day treated males, high levels of testosterone were observed from March to June ( P , 0.05). A treatment-by-time interaction was detected for the intensity of male odor ( P , 0.01). The male odor was stronger in long-day treated bucks than in untreated ones from March to June ( P , 0.05). The number of ano-genital sniffing, nudging and flehmen was greater in long-day treated males than in untreated ones when exposed to anestrous does ( P , 0.05). In experiment 2, one group of males was left under natural photoperiod variations ( n 5 5) and the other ( n 5 5) was submitted to the same photoperiodic treatment described in experiment 1. On 3 May, three untreated and three long-day treated males were put in contact with anestrous Alpine does left under natural photoperiod. Fertility was higher in does exposed to light-treated males (36/45, 80%) than those in contact with untreated ones (3/45, 7%; P , 0.05). Prolificacy was similar ( P . 0.05) in does exposed to treated (1.8 6 0.1) and untreated males (1.7 6 0.3). These results indicate that the sexual activity of Alpine male goats raised in subtropical latitudes can be induced using only artificially long days and that such males are effective in stimulating reproductive activity in anovulatory females in late spring.Keywords: seasonal anestrous, photoperiod, male effect, sexual behavior, ovulation ImplicationsThese results demonstrated that, in lactating Alpine female goats raised in subtropical latitudes, sexual activity can be induced during the anestrous season by exposure to males rendered sexually active by a long-day treatment. These results have an important practical application because they show that in subtropical latitudes the photoperiodic treatment of females is not necessary to stimulate their reproductive activity by the male effect, in contrast to that reported for the same breed under temperate latitudes.

“…On January 16, males of the experimental group received two subcutaneous ear melatonin implants and were then exposed to natural photoperiodic changes. This light-treatment during the non-breeding season stimulated LH and testosterone secretion, sexual behavior and sperm production from the end of February to the end of April (Delgadillo et al, 2001). Then, we tested whether these photoperiod-treated bucks could stimulate the sexual activity of anestrous goats.…”

Section: Control Of the Sexual Activity Of Male And Female Goatsmentioning

confidence: 95%

Environmental and social cues can be used in combination to develop sustainable breeding techniques for goat reproduction in the subtropics

2011

Goat breeds from subtropical latitudes show different annual reproductive cycles. Some of them display large seasonal variations in their annual breeding season, while others display a moderate seasonality or sexual activity all year round. This reproductive seasonality causes seasonality of milk, cheese and meat productions and, as a consequence, induces wide variation in producer incomes. To solve this problem and provide methods allowing producers to breed animals during the anestrous period and stabilize production all year round, it is necessary to have a deep knowledge of their annual sexual activity and to identify the environmental factors controlling the timing of the annual reproductive cycle. Then, it is possible to build on these knowledge sustainable breeding techniques adapted to the environmental, economic and social characteristics of the local breeding system. In this review, I will illustrate this strategy through the example of our experiments in subtropical goats. First, we determined the characteristics of the annual breeding season in both male and female goats. Second, we identified the photoperiod as the major environmental factor controlling the timing of this annual breeding season. Third, we used the photoperiod to stimulate indirectly the sexual behavior of does. Indeed, we used photoperiodic treatments to stimulate the sexual activity of bucks during the non-breeding season. These sexually active male goats were then used to induce and synchronize the estrous behavior and ovulatory activity of anestrous females in confined or grazing conditions by using the 'male effect'. Under subtropical conditions, these results constitute an original manner to control the reproductive activity of local goats using the photoperiod combined with the 'male effect.'