Seasonal aspects of reproductive physiology in captive male maned wolves (Chrysocyon brachyurus, Illiger 1815).

The aim of the study was to evaluate the seasonality of andrological characteristics and hormonal profile of captive maned wolves (Chrysocyon brachyurus, Illiger 1811). Three adult males were evaluated from the Companhia Brasileira de Metalurgia e Mineração Scientific Breeding Center in Araxá, MG, Brazil, over 13 months. Semen was collected 2-3 times weekly and analysed. Scrotal circumference, biometrics and testicular volume were measured. Stool samples were collected 2-3 times weekly to analyse corticosteroid and testosterone metabolite concentrations. A success rate of 100% was achieved in the collection attempts during the breeding season (BS) and 77.8% during the non-breeding season (NBS). The interval to achieve penile erection was 1-5 min in the BS and 6-10 in the NBS (p < 0.001). Of the ejaculates collected, 80.0% contained sperm during BS, while 28.6% did during the NBS. The ejaculate had only one fraction, was odourless, predominantly translucent (72.4%), with a watery appearance, pH 6.7 and osmolarity of 352.8 mOsmol. Seasonal influences were seen in ejaculate volume (1.3 ml vs 0.4 ml), number of spermatozoa per ejaculate (73.9 × 10(6) vs 6.1 × 10(6) ) and percentage of live sperm (82.0% vs 66.1%) between the BS and NBS (p < 0.05), respectively. A high percentage of major sperm defects were observed in both seasons (50.1% in BS; 65.7% in NBS). Testicular volume was larger (p < 0.05; right testicles 13.1 cm(3) in BS vs 4.0 cm(3) in NBS, while left testicles 12.9 cm(3) in BS vs 5.3 cm(3) in NBS) and testicular consistency increased in the BS. No difference was seen in the basal faecal metabolite concentrations of testosterone; however, the corticosteroid concentrations were higher in the BS. Based on these results, it is possible to conclude that the collection of semen is feasible in captive maned wolves without compromising libido, seminal characteristics and reproductive behaviour and that sperm production is influenced by seasonality; however, it appears that there is no seasonal influence on basal testosterone concentrations.

Comparison of serum hormone levels of captive and free-living maned wolves Chrysocyon brachyurus.

Serum hormone levels were compared between captive and free-living maned wolves and seasonal variations of sex hormones were studied. Blood samples were collected from 16 male and 26 female adult animals from Brazilian zoos, and from 30 male and 24 female free-living adults to determine serum progesterone and testosterone by radioimmunoassay. Serum testosterone concentrations varied (P < 0.05) across seasons for 16 captive males, being higher in autumn (2184.7 +/- 355.1 pg/mL) than in summer (1080.7 +/- 205.4 pg/mL), winter (1270.1 +/- 276.6 pg/mL) and spring (963.9 +/- 248.1 pg/mL), although they did not differ between summer, winter and spring. Testosterone concentration of 30 free-living males differed (P < 0.05) between autumn (824.1 +/- 512.2 pg/mL), winter (14.4 +/- 8.0 pg/mL) and spring (151.9 +/- 90.5 pg/mL). Comparison between captive and free-living animals showed no difference in autumn (P > 0.05). Sixteen captive males showed higher testosterone concentration during winter and spring compared with 30 free-living animals (P < 0.05). Progesterone concentration varied among seasons in 26 captive females (P < 0.05), being higher in autumn (15.3 +/- 3.1 ng/mL) than in summer (6.6 +/- 1.5 ng/mL), winter (5.3 +/- 3.1 ng/mL) and spring (4.3 +/- 0.7 ng/mL). Progesterone concentration of 24 free-living females varied between autumn (17.1 +/- 6.0 ng/mL) and winter (1.7 +/- 0.3 ng/mL) (P < 0.05), but we could not obtain data for spring or summer. No difference in progesterone levels was observed between captive and free-living females in autumn and winter.

Comparison of serum hormone levels of captive and free-living maned wolves Chrysocyon brachyurus

Serum hormone levels were compared between captive and free-living maned wolves and seasonal variations of sex hormones were studied. Blood samples were collected from 16 male and 26 female adult animals from Brazilian zoos, and from 30 male and 24 female free-living adults to determine serum progesterone and testosterone by radioimmunoassay. Serum testosterone concentrations varied (P < 0.05) across seasons for 16 captive males, being higher in autumn (2184.7 ± 355.1 pg/mL) than in summer (1080.7 ± 205.4 pg/mL), winter (1270.1 ± 276.6 pg/mL) and spring (963.9 ± 248.1 pg/mL), although they did not differ between summer, winter and spring. Testosterone concentration of 30 free-living males differed (P < 0.05) between autumn (824.1 ± 512.2 pg/mL), winter (14.4 ± 8.0 pg/mL) and spring (151.9 ± 90.5 pg/mL). Comparison between captive and free-living animals showed no difference in autumn (P > 0.05). Sixteen captive males showed higher testosterone concentration during winter and spring compared with 30 free-living animals (P < 0.05). Progesterone concentration varied among seasons in 26 captive females (P < 0.05), being higher in autumn (15.3 ± 3.1 ng/mL) than in summer (6.6 ± 1.5 ng/mL), winter (5.3 ± 3.1 ng/mL) and spring (4.3 ± 0.7 ng/mL). Progesterone concentration of 24 free-living females varied between autumn (17.1 ± 6.0 ng/mL) and winter (1.7 ± 0.3 ng/mL) (P < 0.05), but we could not obtain data for spring or summer. No difference in progesterone levels was observed between captive and free-living females in autumn and winter.