Effect of semen collection frequency on seasonal variation in sexual behaviour, testosterone, testicular size and semen characteristics of tropical hair rams (Ovis aries).
28 Apr 2007-Tropical Animal Health and Production (Kluwer Academic Publishers)-Vol. 39, Iss: 4, pp 271-277
TL;DR: The magnitude of the seasonal effects was not sufficient to prevent the rams being used for breeding throughout the year, and seasonal variation within variables was affected differently between semen collection frequencies.
Abstract: The purpose of this study was to examine the effect of day length on seminal characteristics, testicular size, sexual behaviour and testosterone (T4) concentration in Pelibuey rams subjected to different semen collection frequencies. Eighteen intact males were assigned randomly to one of two semen collection frequencies: in the high rate (HR) treatment, two ejaculations per week were obtained from each ram; one ejaculation every two weeks was collected under the low rate (LR) treatment. All animals were housed individually in contiguous 5 m × 5 m wire mesh pens and evaluated over a 12-month period. At the beginning of the experiment rams were 20 months old and 40–50 kg in weight. All rams ejaculated and produced semen throughout the year. Semen volume, sperm per ejaculation, testicular circumference and testicular volume were significantly (p < 0.05) greater during short days in all rams, regardless of the semen collection frequency, with the exception of sperm concentration, for which no variation was found in HR individuals, and reaction time and T4 levels, for which no variation was found in LR males. Rams subjected to HR collection were more affected by the short-day photoperiod than rams collected twice per week, exhibiting greater reduction (p < 0.05) in time to achieve their first ejaculation and in sperm per ejaculation, as well as greater increases (p < 0.05) in T4 concentration than LR rams (14.65 ± 1.22 vs 23.53 ± 5.34 s, (3.37 ± 0.17) × 109 vs (3.52 ± 0.20) × 109 sperm and 8.68 ± 0.44 vs 6.85 ± 0.74 ng/ml, respectively). It was concluded that: (a) the magnitude of the seasonal effects was not sufficient to prevent the rams being used for breeding throughout the year, and (b) seasonal variation within variables was affected differently between semen collection frequencies.
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TL;DR: It is shown that, in the great pond snail Lymnaea stagnalis, receipt of specific SFPs reduces both sperm transfer and paternity success in a subsequent insemination event, demonstrating for the first time that hermaphrodites alter their mates' male as well as female reproductive output.
47 citations
Journal Article•
TL;DR: Ejaculates of both types of crossbreds were characterised by greater spermatozoon motility compared with purebred boars, irrespective of the month of ejaculate collection.
Abstract: The experimental material consisted of 12,285 ejaculates obtained from 93 boars, including 18 Duroc boars, 30 Pietrain boars, 24 ♀Duroc x ♂Pietrain crossbreds and 21 ♀Pietrain x ♂Duroc crossbreds. The boars were utilised for at least 6 months and qualified for insemination from January 1, 1992 to December 31, 2007. Each ejaculate was assessed using standard methods for the following physical traits: volume, sperm concentration, spermatozoon motility, total number of spermatozoa, and number of insemination doses per ejaculate. The data obtained were classified into 12 sub-groups consisting of ejaculates collected in successive months. Ejaculates collected in the summer months had less spermatozoa than in the autumn and winter period. Ejaculates collected in the summer (mainly in July) yielded the least amount of insemination doses. Ejaculates of both types of crossbreds were characterised by greater spermatozoon motility compared with purebred boars, irrespective of the month of ejaculate collection.
32 citations
Cites background from "Effect of semen collection frequenc..."
...(1) demonstrated that there was an impact of the length of photoperiod on the sexual activity of males....
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TL;DR: It is indicated that environmental conditions are important source of variation in litter size, birth, and weaning weight in hair sheep under semi-arid climate.
Abstract: This study was conducted to evaluate the effects of season, year of lambing, parity, and the effect of ram on litter size, birth, and weaning weight through 8 years. Data of 4078 lambs sired by 21 rams and 1072 ewes were analyzed by a lineal model. There was a significant effect (P 0.05). For litter size, the lowest numbers were obtained on the first lambing ewes (1.21 ± 0.03) and the highest ones inewes starting from the fourth lambing (1.69 ± 0.04). Lowest body weights were found in lambs born from first lambing ewes (3.01 ± 0.1 kg) and the highest ones in lambs born from the second (3.14 ± 0.1) to the fifth (3.15 ± 0.2) lambing ewes. The lambing breeding season had a significant effect on weaning weight: the highest weaning weights were recorded in lambs born in spring (12.70 ± 0.20 kg) and the lowest ones in those born in summer (11.93 ± 0.20 kg). Lambing year had a significant effect (P < 0.05) on litter size and weaning weight, since the values of both traits improved through the years. Effect of ram was significant (P < 0.05) for each of the traits considered: there were differences up to one lamb per litter, also differences up to 1.5 kg for birth weight and up to 6.5 kg for weaning weight among rams. In conclusion, these results indicate that environmental conditions are important source of variation in litter size, birth, and weaning weight in hair sheep under semi-arid climate.
22 citations
Cites background or methods from "Effect of semen collection frequenc..."
...Progressive motility, concentration, abnormality, and viability were assessed as described by Aguirre et al. (2007)....
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...…can make positive genetic progresses; hence, the reproductive performance of the flocks will be benefited up to 8–10 % throughout the years (in Saint Croix breed, Wildeus 2005 and Aguirre et al. 2007; in Blackbelly breed, González et al. 2003; and in Finnsheep breed, Afolayan et al. 2008)....
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TL;DR: In conclusion, alterations in both ram testes blood flow and echotexture seem to be moderately correlated with sperm assessed parameters, depending on season and ram age.
Abstract: This study investigated correlations among ram semen quality parameters, testicular vascularity and echotexture. Measurements were performed biweekly for a year, before (BE) and after ejaculation (AE), on seven Chios breed rams [three rams (group A) and four rams (group B) of 2-6 and 9-13 years old, respectively], considering breeding (1) and non-breeding period (2). Hemodynamics [Pulsatility Index (PI), Resistive Index (RI)] were evaluated in each testis. Images of testicular parenchyma were analysed to evaluate echogenicity [Mean Value (MV), Contrast (Con), Gray Value Distribution (GVD), Run Length Distribution (RunLD), Long Run Emphasis (LRunEm)]. Semen volume (V), concentration (C), kinetics (CASA), morphology (Sperm Blue), viability (Eosin-Nigrosin) and DNA fragmentation (Acridine Orange) were assessed. In group A/2, semen V was correlated to left testis PI and right testis RI, BE (r = 0.4, p = 0.013/r = 0.6, p < 0.001, respectively), and to right testis PI and RI, AE (r = 0.5, p < 0.001). In A/1/AE, semen C was correlated to left testis PI (r = -0.5, p = 0.003). In group A/1/BE, RI of both testes was correlated to total and tail abnormalities (left: r = -0.5, p = 0.008/ p = 0.004, respectively - right: r = -0.4/r = -0.5, p = 0.01/ p = 0.008, respectively). In group B/1/BE, sperm tail and total abnormalities were correlated to left testis Con (r = 0.5, p = 0.02/ p < 0.001, respectively), whereas in A/2/BE, they were correlated to left testis LRunEm (r = -0.8/r = -0.7, p < 0.001, respectively). In group A/1/BE, DNA damage was correlated to right testis LRunEm (r = -0.6, p < 0.001) and tail abnormalities to left testis PI (r = -0.5, p = 0.03). In group B/1/AE, right testis LRunEm, GVD, RunLD, were correlated to sperm DNA integrity (r = -0.9, p < 0.001). Immotile spermatozoa and viability were correlated to left testis Con in group B/2/AE (r = -0.6/r = 0.6, p < 0.001) and to right testis MV in group A/1/AE (r = -0.6/r = 0.6, p < 0.001). In conclusion, alterations in both ram testes blood flow and echotexture seem to be moderately correlated with sperm assessed parameters, depending on season and ram age.
16 citations
Journal Article•
TL;DR: Testosterone profi les is not a notable factor for estimating the quality of crossbred rams spermatogenesis and sexual activity, and scrotal circumference showed a positive correlation with reaction time for the second ejaculation, semen pH and spermatozoa concentration.
Abstract: Background: Measurements of testosterone, scrotal circumference and libido have a great value as indicators of onset of puberty, total semen production, semen quality, control of spermatogenesis, testicular state, pathological conditions of testes and the potential sub-fertility or infertility. Therefore, the aim of this study was to determine relationship between levels of peripheral blood testosterone, sexual behavior, scrotal circumference and seminal parameters in crossbred rams. Materials, Methods & Results: Twelve crossbred and sexually mature rams consisting¬ of three Arkharmerino × Moghani (AM × MG), three Baluchi × Moghani (BL × MG), and three Ghezel × Baluchi (GH × BL) and three Ghezel × Arkharmerino (GH × AM) were used in this study. The scrotal circumference (SC) was measured at monthly intervals. Every two weeks the 12 crossbred rams were evaluated for the degree of libido using three ovariectomized ewes. Sexual behavior of crossbred rams was evaluated in terms of (1) reaction time for the fi rst and second ejaculate (2) time taken for the fi rst and second ejaculate (3) number of mounts for the fi rst and second ejaculation. Ram semen was collected by artifi cial vagina and blood samples were obtained via jugular vein. Soon after the collection, semen characteristics and testosterone plasma were assayed. For estimation of the relationship between genetic group and other indices, Statistical analyses were performed by One-way ANOVA and Bivariate correlation coeffi cient was used to calculate the correlations between testosterone by spermatozoa parameters and libido in each genetic group; P < 0.05 considered signifi cant. The results showed that there were no signifi cant differences between crossbred rams in terms of semen characteristics except for spermatozoa progressive motility, semen volume and pH. The highest level of plasma testosterone was recorded in GH × BL rams (7.12 ± 1.87 ng/mL) and the lowest was for AM × MG genetic group (2.99 ± 1.90 ng/mL). However, any signifi cant difference wasn’t observed among the four genetic groups about plasma testosterone. At the present study the mean values of scrotal circumference of Arkharmerino × Moghani were higher than other genetic groups (P < 0.05). Also scrotal circumference showed a positive correlation with reaction time for the second ejaculation, semen pH and spermatozoa concentration (P < 0.05). Discussion: The sexual activity of males is infl uenced by test conditions and the methods applied in tests can vary considerably, even within the same experiment for example with regard to test duration and number of males and females. Among libido indices, only a signifi cant correlation was observed between reaction time for second ejaculate and scrotal circumference. A non-signifi cant correlation was observed between plasma testosterone, concentration, and semen traits. These differences between various reports could be due to the season of the study, breed, age of rams and many other environmental factors. It could be concluded that testosterone profi les is not a notable factor for estimating the quality of crossbred rams spermatogenesis and sexual activity. In addition to the above points, the males should be examined for a number of different tests have been used to assess the fertility or performance of crossbred rams, including scrotal measurement, semen examination, libido testing, hormonal profi le and the other examinations.
14 citations
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TL;DR: The design and analysis of experiments in the animal and medical sciences and the results show clear trends in animal studies and in the medical sciences are consistent with each other.
Abstract: Design and analysis of experiments in the animal and medical sciences , Design and analysis of experiments in the animal and medical sciences , مرکز فناوری اطلاعات و اطلاع رسانی کشاورزی
825 citations
TL;DR: The seasonal cycle highlights the seasonal changes in daylight length, rutting behavior, testicular diameter, sexual skin flush, and concentrations of plasma follicle-stimulating hormone, prolactin, and testosterone in a group of rams throughout the year.
Abstract: Publisher Summary This chapter focuses on the seasonal control of fertility. It discusses two aspects in detail—the way in which changes in the secretion of luteinizing hormone-releasing hormone by the hypothalamus controls the activity of the pituitary and testis, and the way changes in day length influence the activity of the hypothalamus. The downstream events evoked by the hypothalamus are relatively easy to understand, whereas the mechanisms involved in the photoperiodic control are very complex and largely unresolved. While seasonal changes in temperature, rainfall, and food availability are the factors of the environment that dictate survival of adults and young—and are thus ultimately responsible for dictating the timing of the birth season—these are not necessarily the factors used as cues by the animals to regulate their reproductive endocrinology. This is because it is necessary to anticipate the timing of birth by dictating the timing of conception, as the duration of gestation in mammals is usually fixed. As accurate timing of conception is important, animals tend to become reliant on cues from the environment, which are the best predictors of the time of year. The seasonal cycle highlights the seasonal changes in daylight length, rutting behavior, testicular diameter, sexual skin flush, and concentrations of plasma follicle-stimulating hormone, prolactin, and testosterone in a group of rams throughout the year.
595 citations
Additional excerpts
...(Lincoln and Short, 1980; Haynes andSchanbacher, 1983; Pelletier and Almeida, 1987)....
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TL;DR: A waning success in siring counters a ram's high score in competition for ewes.
Abstract: A waning success in siring counters a ram's high score in competition for ewes.
362 citations
"Effect of semen collection frequenc..." refers background in this paper
...Males with an increased copulation frequency have more reproductive success (Preston et al., 2001) as they generally serve more ewes more times (Price et al....
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...Males with an increased copulation frequency have more reproductive success (Preston et al., 2001) as they generally serve more ewes more times (Price et al., 1996)....
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...Larger testicles produce more semen since the rate of semen production per unit of testis weight is constant (Gherardi et al., 1980; Preston et al., 2001)....
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TL;DR: The manifestations of seasonality in both the ram and the ewe are described and special emphasis is given to the neuroendocrine base of photoperiodic regulation of seasonal breeding.
272 citations
"Effect of semen collection frequenc..." refers background in this paper
...…Ciencias Agropecuarias de la Universidad Autónoma del Estado de Morelos, Av. Universidad 1001 Col. Chamilpa, Cuernavaca, Morelos 62210, México e-mail: aorihuela@uaem.mx environments, some breeds have been reported to be almost or completely aseasonal (Thimonier et al., 1986; Rosa and Bryant, 2003)....
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...environments, some breeds have been reported to be almost or completely aseasonal (Thimonier et al., 1986; Rosa and Bryant, 2003)....
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