We evaluated sexual behavior of St. Croix White (SC; n = 5) and Barbados Blackbelly hair (BB; n = 4) rams under two environmental conditions in the tropics. Sexually naive rams were individually exposed for 15 min to a restrained, ovariectomized ewe, three times during a 3-wk period in June, in a pen with shade (SHADE; 33.1+/-.3 degrees C) or without shade (SUN; 38.3+/-.3 degrees C). Rectal temperature (RT) of rams was measured before and after each test. Sexual behaviors were recorded by observers outside the pens. The number of mounts and ejaculations were similar (P > .10) between the SUN (12.1+/-2.8 and 3.6 +/-.5, respectively) and SHADE (10.7+/-2.9 and 3.4+/-.4, respectively) tests. There was no breed x test pen interaction for any of the behaviors recorded (P > .10). The BB rams mounted the ewe more (P < .04) than did the SC rams (15.7+/-2.8 vs 7.3+/-2.7 mounts, respectively). The overall level of activity (foreleg kicks, attempted mounts, mounts, and ejaculations) was similar (P > .10) between BB and SC rams (64.9 +/-8.5 vs 45.4+/-8.5 events, respectively). Rectal temperature before testing was similar (P > .10) in BB and SC rams (39.4+/-.1 vs 39.4+/-.1 degrees C, respectively). The change in RT of rams was not different (P > .10) between SUN and SHADE tests (.6 +/-.1 vs .8+/-.1 degrees C), but BB rams had a greater (P < .02) change in RT than SC rams (.9+/-.1 vs .5+/-.1 degrees C, respectively). The change in RT was positively correlated with time to first service (r = .39, P < .01) and number of mounts (r = .52, P < .001) and negatively correlated with number of services (r = -.47, P < .0008). These results show that under tropical conditions, hair sheep rams exhibit a full repertoire of sexual behaviors. There does not seem to be a negative influence of elevated ambient temperature during testing on the level of sexual behavior of these rams.
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"These behaviours are considered as libido activities that males use in order to determine the sexual receptivity of females (Price et al 1992, Ungerfeld and Gonzalez 2008). These sexual behaviours are indicative of hair sheep (Godfrey et al 1998) and other breeds (Kridli et al 2007). All hair rams exhibited a full repertory of sexual behaviour throughout the three seasons. "
[Show abstract][Hide abstract] ABSTRACT: The objectives of the present study were to evaluate the libido and serving capacity of Pelibuey (PB), Blackbelly (BB), Dorper (DR) and Katahdin (KA) hair sheep rams in three seasons under tropical environmental conditions. Twenty-eight mature rams were individually exposed for 10 minutes to an immobilized, oestrous-induced ewe twice per season. The total number of sexual behaviours, reaction time to first mating and latencies between mating were recorded. Reaction time and latencies were affected by breed effect (P < 0.05) and except for the latency time for the second ejaculation, the season was also significant (P < 0.05) while no interaction effects were observed (P > 0.05). All rams attained at least one ejaculation during testing. The overall mean (± S.E.M.) of reaction time and latencies to second and third mating were 37.62 ± 4.97s, 136.43 ± 9.75 and 180.95 ± 11.87 seconds, respectively. PB, BB and KA rams were faster than DR in reaction time and latency to second mating (P < 0.05). For latency to third mating, PB and KA rams were faster than BB and DR (P < 0.05). The libido activities that rams performed most frequently were anogenital sniffing and foreleg kicks. It was concluded that under tropical environmental conditions PB, KA and BB rams showed better serving capacity than DR, with shorter reaction time and latency to second mating. Hair rams exhibited more frequencies of anogenital sniffing and foreleg kicks.
Full-text · Article · Dec 2014 · Archivos de Medicina Veterinaria
"Measurements of ram sexual development may be useful for predicting reproductive capacity in rams sires (Katz et al., 1988; Price et al., 2000). Sexual behavior differs between breeds and herd management plays an important role in the speed of the start of puberty (Godfrey et al., 1988; Maina and Katz, 1997; Price et al., 2000, 2001). Although spermatogenesis is an organized process throughout the life of the male (Cheng et al., 2010; Michelle et al., 2009; Leblond and Clermont, 1952), it does not occur simultaneously in all seminiferous tubules but rather in wave-like sequences of maturation, referred to as cycles of the semniferous epithelium. "
[Show abstract][Hide abstract] ABSTRACT: This experiment was designed to study the relationship between growth rate and sexual development in Najdi ram lambs. Forty-five Najdi ram lambs were used in nine age groups (1–9th month age), keeping 5 lambs in each group. Results show that mean testis size and scrotal circumference increased at a constant rate, reaching a maximum value of 392.00 ± 2.00 g and 25.00 ± 0.32 cm respectively, at the age of 9 months. A similar trend of growth was observed for the mean body weight, reaching a maximum value of 40.2 ± 0.20 kg at the age of 9 months. There was a positive correlation between the increasing rates of body weight and size of the testis. There were significant differences (P < 0.05) in testis size, scrotal circumference and body weight of lambs between all ages (1–9 months). The histological section of testis showed that a small number of mature sperms appeared in the eighth month of age and their numbers increased in the ninth month. In conclusion, the current findings indicated that puberty in Najdi rams occurs between the 8th and 9th months of age.
Full-text · Article · Jan 2013 · Saudi Journal of Biological Sciences
"Unlike woolled sheep that have evolved in temperate regions, hair sheep show no evidence of a photoperiodic effect on fertility at tropical latitudes (Fitzhugh and Bradford 1983). Furthermore, Godfrey et al (1998) observed that under tropical conditions, Saint Croix rams display full reproductive activity during June. This breed adaptation to photoperiod and temperature explain why Suffolk males displayed a decrease in their daily sexual activity during the mid-day hours, when there is an increase in solar radiation, unlike the more stable sexual activity of Saint Croix rams. "
[Show abstract][Hide abstract] ABSTRACT: En las razas de origen templado, la conducta sexual disminuye durante los días largos, mientras que en los carneros tropicales se observa poco este efecto. Sin embargo, los cambios en la conducta sexual entre estas dos razas no se han comparado, y tampoco se han considerado para su análisis otros factores ambientales que pudieran estar involucrados, diferentes a la longitud del día. El propósito de este estudio preliminar fue el de evaluar la conducta sexual de carneros Santa Cruz y Suffolk a latitudes medias (19º N), durante días largos, durante su exposición a borregas Suffolk en anestro estacional, con el fin de evitar la retroalimentación sexual de las hembras. En el primer grupo (T1), tres machos Suffolk se expusieron de manera continua por 13 días a las hembras, mientras que en el segundo grupo (T2) se utilizaron tres machos Santa Cruz. Los machos Santa Cruz realizaron más (P < 0,05) vocalizaciones y olfateos que los Suffolks (60,6 ± 12.4 vs. 26,8 ± 5,4 y 141,9 ± 17,1 vs. 62,5 ± 11,2, frecuencias/h, respectivamente). La actividad sexual disminuyó (P < 0,01) en los carneros Suffolk a medida que el experimento transcurrió (y = 1,72x + 42,76; P < 0,05), sugiriendo una habituación a largo plazo hacia las hembras. Además, la actividad sexual también disminuyó durante el mediodía en un patrón altamente relacionado (r = 0,8; P < 0,05) con la luz solar, mientras que los machos Santa Cruz mantuvieron un patrón más homogéneo de actividad sexual entre y dentro de los días. Se concluye que a latitudes medias (19º N) la menor actividad sexual de los carneros Suffolk en comparación con los Santa Cruz durante los días largos se ve exacerbada por el efecto de la radiación solar y la habituación a hembras sexualmente inactivas.
Full-text · Article · Dec 2012 · Archivos de Medicina Veterinaria