title: Reducing exposure to long days from 75 to 30 days of extra-light treatment does not decrease the capacity of male goats to stimulate ovulatory activity in seasonally anovulatory females.
abstract: The response of male goats exposed to different durations of long days (LD) during an extra-light treatment in autumn-winter, and their ability to induce ovulations in seasonally anovulatory goats were investigated in 2 experiments. In experiment 1, control males were exposed to natural photoperiod (n = 5), whereas 4 additional groups (n = 5/group) were exposed to 16 h of light per d during 75, 45, 30, or 15 d of LD. In the 4 groups, photoperiodic treatments ended on January 15th. Plasma concentrations of testosterone were determined in blood samples obtained once a week from October 15th to May 30th. The rise of testosterone levels occurred earlier in males from the 75-LD and 45-LD groups than in those from the 30-LD, 15-LD, and control groups (P < 0.05). In addition, the time during which levels of testosterone remained >5 ng/mL was longer in males from the 75-LD and 45-LD than in those from the 30-LD and 15-LD groups (P < 0.05). In experiment 2, a group of anovulatory goats (n = 13) was isolated from males, while 3 additional groups were put in contact during 15 d with males previously exposed to 75, 45, or 30 days of LD (n = 25, 27, and 26 females/group, respectively and n = 3 males per group). The proportion of goats that ovulated was higher in the 3 groups in contact with the photo-stimulated males (range: 88%-92%) than in the group isolated from them (0%; P < 0.05). The proportion of pregnant females did not differ between the 3 groups of does in contact with photo-stimulated males (range: 78%-92%; P > 0.05). We conclude that, in our experimental conditions, a photoperiodic treatment as short as 30 d of LD during autumn-winter, stimulated testosterone secretion of bucks during their period of sexual rest and rendered them able to induce ovulations in seasonal anestrous goats and to obtain pregnancies in these females.
authors.affiliation: Centro de Investigación en Reproducción Caprina, Universidad Autónoma Agraria Antonio Narro, Periférico Raúl López Sánchez y Carretera a Santa Fe, Torreón, Coahuila, México.
authors.forename: J L
authors.initials: JL
authors.lastname: Ponce
authors.affiliation: Centro de Investigación en Reproducción Caprina, Universidad Autónoma Agraria Antonio Narro, Periférico Raúl López Sánchez y Carretera a Santa Fe, Torreón, Coahuila, México.
authors.forename: H
authors.initials: H
authors.lastname: Velázquez
authors.affiliation: Centro de Investigación en Reproducción Caprina, Universidad Autónoma Agraria Antonio Narro, Periférico Raúl López Sánchez y Carretera a Santa Fe, Torreón, Coahuila, México.
authors.forename: G
authors.initials: G
authors.lastname: Duarte
authors.affiliation: Centro de Investigación en Reproducción Caprina, Universidad Autónoma Agraria Antonio Narro, Periférico Raúl López Sánchez y Carretera a Santa Fe, Torreón, Coahuila, México.
authors.forename: M
authors.initials: M
authors.lastname: Bedos
authors.affiliation: Centro de Investigación en Reproducción Caprina, Universidad Autónoma Agraria Antonio Narro, Periférico Raúl López Sánchez y Carretera a Santa Fe, Torreón, Coahuila, México.
authors.forename: H
authors.initials: H
authors.lastname: Hernández
authors.affiliation: Physiologie de la Reproduction et des Comportements, UMR 7247 INRA-CNRS Université de Tours-37380, Nouzilly, France.
authors.forename: M
authors.initials: M
authors.lastname: Keller
authors.affiliation: Physiologie de la Reproduction et des Comportements, UMR 7247 INRA-CNRS Université de Tours-37380, Nouzilly, France.
authors.forename: P
authors.initials: P
authors.lastname: Chemineau
authors.affiliation: Centro de Investigación en Reproducción Caprina, Universidad Autónoma Agraria Antonio Narro, Periférico Raúl López Sánchez y Carretera a Santa Fe, Torreón, Coahuila, México. Electronic address: joaldesa@yahoo.com.
authors.forename: J A
authors.initials: JA
authors.lastname: Delgadillo
mesh_terms: D000818:Animals; D005260:Female; D006041:Goats / Q000502:physiology*; D008297:Male; D010060:Ovulation / Q000502:physiology*; D017440:Photoperiod; D012621:Seasons; D012726:Sexual Behavior, Animal; D013997:Time Factors
keywords: Caprine; Male effect; Ovulation; Photoperiod; Sexual behavior; Testosterone secretion