Seasonal variation in semen characteristics of White Leghorn,New Hampshire and indigenous chicken in Iraq

1. The effects of season, temperature, humidity and light on semen volume, pH, concentration, motility and the proportions of dead and abnormal spermatozoa were investigated on White Leghorn, New Hampshire and Iraqi cockerels.

2. All semen characteristics, with the exception of pH, were significantly influenced by season.

3. The semen quality of the Iraqi breed was similar to that of the New Hampshire breed.     

Seasonal variation in semen quality of bulls and correlations with metabolic and endocrine parameters

Sperm output and semen quality of 17 bulls sampled over 12 months showed minimal output in mid-winter and late summer and minimum quality in late summer. Monthly measurements of luteinising hormone and testosterone concentration in plasma and testosterone concentration in semen were made over 12 months. Serum non-esterified fatty acids (NEFA), albumin and total protein were also measured for the final seven months of this period. Plasma testosterone showed a strong negative correlation with sperm numbers two months hence but not in the current month. Plasma testosterone by bull and semen testosterone by month was also correlated with sperm output. Plasma luteinising hormone three months and serum total protein two months prior was positively correlated with sperm numbers ejaculated and the normality of sperm morphology, possibly by affecting the luteinising hormone dependent A0 to A1 spermatogonial division. NEFA was correlated with initial and post freezing/thawing motility in the current month, possibly by affecting membrane stability. The value of examining the bull in diagnosing infertility of cows where nutritional stress may have occurred is suggested, as is the use of albumin/total protein and NEFA measurements as a prognostic aid for time to return to normality of function of such bulls.     

Forms of Reproductive Disorders in Cattle and Buffaloes in Middle Egypt

The objective of this study was to investigate the common forms of reproductive disorders and trends of fertility in cattle and buffaloes in Middle Egypt, and investigate nutritional deficiencies or imbalances as a cause of infertility. During the period from 2003 to 2006 a total of 4276 animals (2755 cattle and 1521 buffaloes) were examined, during winter and summer at three districts of Middle Egypt. Based on the owner complains, animals were categorized as anestrum, repeat breeder and those for pregnancy diagnosis. Feedstuffs of these districts were assessed for nutrient and mineral contents. Animals were examined by rectal palpation and by transrectal ultrasonography. The results showed that, ovarian inactivity was the most common cause of anestrum, whereas endometritis was the main frequent finding of repeat breeding. District, season and year affected the incidences of infertility. The pregnancy rate remained constant (cattle) or increased (buffaloes) from 2003 to 2006. The incidence of ovarian inactivity in both species decreased over the same period. In winter, the commonly used feedstuffs would be adequate to supply the animals with needs, but in summer, rations seem to be deficient in many essential nutrients. In conclusion, ovarian inactivity is the main cause of infertility in cattle and buffaloes in Middle Egypt. There is a link between poor nutrition in summer and the high incidence of ovarian inactivity. Fertility trends during the past few years are encouraging.     

Mycobiotic Flora of Female Genitalia of Buffaloes and Cows with Reproductive Disorders

Veterinary Research Communications -     

Reproductive Performance of Purebred Swedish Landrace and Swedish Yorkshire Sows: I. Seasonal Variation and Parity Influence

The objective of this retrospective study was to investigate the causes of variation in the reproductive performance of purebred Swedish Landrace (L) and Swedish Yorkshire (Y) sows. Data analysed comprised farrowings from 1994 through 1997 from 19 Swedish nucleus herds and included 20 275 litters from 6989 purebred sows (3598 L and 3491 Y). The main traits analysed were litter size, weaning-to-first-service interval (WSI), farrowing rate, remating rate and age at first farrowing. Analysis of variance was used for the statistical analysis of quantitative data. Logistic regression analysis was applied for binary data using the GLIMMIX macro in the SAS program. Factors included in the analyses were breed of sow, breed of boar, parity number, herd-year combination within breed, mating type (natural mating or artificial insemination), lactation length and month of the year. L sows, compared with Y sows, produced larger litters [11.61 vs 11.54 total born/litter (ns) and 10.94 vs 10.58 born alive/litter (P<0.001)] and had a longer WSI (5.5 vs 5.4 days, P<0.001), a higher farrowing rate (82.8 vs 80.9% units, P<0.05) and a lower remating rate (6.2 vs 8.8% units, P<0.001). On average, L sows were younger at first farrowing than Y sows (355.6 vs 368.6 days, P<0.001). The seasonal influence on WSI was greater for primiparous sows than for multiparous sows. Primiparous sows weaned from June to October had a longer WSI than those weaned from January to May or in November (P<0.05). Mating in August resulted in the lowest farrowing rate and the highest remating rate. The seasonal influence on farrowing rate and WSI was more pronounced in Y sows than in L sows. However, season had no significant influence on litter size in either L or Y sows.     

Seasonal Variation of Reproductive Performance,Foetal Development and Progesterone Concentrations of Sheep in the Subtropics

The aim of the present study was to investigate the effect of breeding season [late spring (LSP) vs winter (WIN)] on reproductive performances, foetal development and progesterone (P₄) concentrations of sheep in the subtropics. Ewes of Farafra breed were exposed for mating in LSP (n = 79) and WIN (n = 45). Ultrasonographic examinations were performed at days 25, 45 and 75 of mating to estimate the pregnancy rate, incidence of twinning and percentage of foetal losses. Foetal growth rate was determined at 10‐day interval, and blood samples were taken on days 0 (oestrus), 8, 18 of oestrous cycle and on days 30, 45, 60 and 90 of pregnancy for P₄ analysis. The results showed that pregnancy and lambing rates were greater (p < 0.01) for ewes mated in LSP (93.7% and 92.4%) than for those mated in WIN (75.6% and 71.1%), respectively. There was no effect of season on the incidence of twinning (overall 19.1%) or the frequency of foetal losses (overall 7.3%). Transient reduction of placental size, foetal growth and P₄ concentration was observed following LSP matings. In conclusion, pregnancy and lambing rates were higher following LSP matings. Summer heat stress of the late spring mated ewes transiently interferes with foetal growth and P₄ concentrations.     

An apparent Effect of Immunopotentiation During Late Gestation on the Postpartum Reproductive Performance of Nili-Ravi Buffaloes (Bubalus Bubalis)

Thirty-two Nili-Ravi buffaloes were used to determine the effect of prepartum immunopotentiation in late gestation with levamisole hydrochloride (0.5 mg/kg), vitamin E+selenium (vitE-Se) (Etosol-SE, 10 ml intramuscularly) or Bacille Calmette Guerin (BCG) (0.5 ml/animal, subcutaneously) on postpartum reproductive performance. The immunopotentiating treatment was given twice, with treatments one week apart, approximately 80 days prior to the expected date of parturition. Prepartum treatment with vitE-Se or BCG significantly (p<0.05) reduced the calving to first oestrus interval and the length of the postpartum service period compared to the control group. The uterine involution period was significantly shorter in buffaloes treated with vitE-Se compared to the control group. Levamisole hydrochloride apparently improved the reproductive performance, but this result was not statistically significant.     

Seasonal variations in sexual behavior, testosterone, testicular size and semen characteristics, as affected by social dominance, of tropical hair rams (Ovis aries)

The purpose of this study was to examine the effect of day length on seminal characteristics, testicular size, sexual behavior and testosterone concentration (T4) in dominant and subordinate Pelibuey rams. Six groups of three animals were evaluated every 2 weeks over a 12 month period. Dominant (D), medium (M) and subordinate (S) animals in each group were identified through a food competition test every 15 days. All rams ejaculated and produced semen throughout the year. A linear hierarchy was clearly established and maintained during the year. S rams had lower levels (P < 0.05) of semen volume, sperm concentration and testicular volume than D rams, regardless of season. Scrotal circumference was not influenced (P > 0.05) by their social position. D rams were more affected by the photoperiod, decreasing (P < 0.05) reaction times, increasing (P < 0.05) T₄ and producing more (P < 0.05) sperm per ejaculation than S rams during short days (14.65 ± 1.22 vs 26.92 ± 1.65 s; 8.68 ± 0.44 vs 7.37 ± 0.40 ng/mL and 3.37 ± 0.17 vs 2.04 ± 0.16 sperm/10⁹, respectively). Semen volume and sperm concentration were significantly (P < 0.05) greater during short days in all rams, regardless of their social status, with the exception of sperm concentration in D rams where no variation was found. M rams displayed variable values in the range between the D and S rams. It was concluded that the magnitude of the seasonal effects was not sufficient to prevent the rams being used for breeding throughout the year and that seasonal variation within the variables affected the social ranks differently.     

Behavioural responses of cockerels to semen collection and their influence on semen characteristics.

One-hundred-and-twenty cockerels of Strain L2 Taiwan Country chicken from the National Chung-Hsing University were tested for their behavioural responses to semen collection at 21 to 30, 34 to 43 and 57 to 66 weeks of age. At every age period, semen was collected from every cockerel 4 times within a 1-week period. 2. Cockerel performances on most semen traits, including volume, concentration, total number of sperm, ease of collection and sensitivity to massage were very consistent within each age period. 3. Males that did not respond nervously to handling or were less sensitive to massage appeared to produce less semen. However, contamination was more serious in males that responded very nervously or were very sensitive to massage. 4. Sensitivity to massage, like semen volume, is an invariant character as indicated by the high correlation between measures taken at different age periods.     

The Effect of Seasonal Thermal Stress on Lipid Mobilisation,Antioxidant Status and Reproductive Performance in Dairy Cows

Heat stress is a major factor contributing to low fertility of dairy cows with a great economic impact in dairy industry. Heat‐stressed dairy cows usually have reduced nutrient intake, resulting in a higher degree of negative energy balance (NEB). The aim of this study was to investigate the seasonal thermal effect on lipid metabolism, antioxidant activity and reproductive performance in dairy cows. Thirty‐two healthy dairy heifers were included in the study. According to the ambient temperature, animals were divided into two groups: winter (N = 14) and summer season (N = 18). Metabolic parameters, paraoxonase‐1 (PON1) activity and total antioxidant status (TAS) were monitored at the time of insemination (basal values) and from 1 week before until 8 weeks after calving. Number of services per conception and calving‐to‐conception (CC) interval were calculated from the farm recording data. Serum triglyceride, non‐esterified fatty acids (NEFA) and beta‐hydroxybutyrate (BHB) concentrations were significantly increased after calving in summer compared to winter, indicating higher degree of NEB in cows during summer. PON1 activity was significantly decreased after calving in both summer and winter group. TAS concentration was significantly lower in summer than that in winter. A significantly higher number of services were needed for conception in summer compared to winter, and CC interval was significantly longer in summer than that in winter as well. Additionally, reproductive performance significantly correlated with the severity of NEB, suggesting that lipid mobilization and lower antioxidant status contributed to poor reproduction ability in dairy cows during hot months.     

Effect of frequent ejaculation on semen characteristics in rams.

Sixteen Suffolk rams were ejaculated repeatedly for a period of eight hours during the month of November. Ejaculates were examined for semen characteristics. Volume density and number of sperm per ejaculate declined significantly in successive ejaculates. Motility and percentage abnormal sperm were not affected by frequent collection. It is concluded that the number of sperm per ejaculate, after the eighth ejaculate, could fall below that required for fertilisation to occur, particularly in progestagen treated ewes.     

AMS(Wistar)封闭群大鼠的繁殖性能及季节对其影响的研究

军事医学科学院动物中心饲养的大鼠源于Wistar鼠种,已封闭饲养40多年,被称为AMS(Wistar)封闭群大鼠.本试验对饲养于开放系统的该群大鼠繁殖性能进行了研究,同时观察了胎次、季节对其的影响.试验结果表明,该群大鼠具有较高的繁育性能,平均窝产仔数、窝初生重、个体初生重、交配妊娠率和交配至分娩间隔天数分别为11.67±3.05只(2～21只)、85.05±19.96g、6.47±0.89g(3.7～10g)、95.45％和24.79±1.61 d(20～30d).后代性比为?:?=1.15:1,有显著的偏雄现象.窝产仔数遗传力h~2=0.378.在每窝留养10只仔鼠情况下,断奶个体重为61.39±8.67g(31～85g),断奶成活率为91.20％.随着胎次的增加,大鼠的窝产仔数、体重初生重、断奶重、断奶成活率等繁殖性能逐渐增大,到第三胎最大,以后下降.此外,该群大鼠的繁殖性能受季节影响很大.交配至分娩的间隔天数7、8月份短,其他月份较长,与舍内月平均温度成负相关γ=0.556(P>0.05).大鼠繁殖所需最适温度为21～25℃.     

雄性恒河猴生殖功能的季节性变化

采用随机抽样法和放射免疫测定法 ,分析了雄性恒河猴在不同季节的体重、睾丸容积、射精量、促卵泡刺激素(FSH)、促黄体生成素 (L H)和睾酮的变化情况。试验结果显示 ,雄性恒河猴的体重、睾丸容积和射精量的变化受季节因素的影响。在非生殖季节 ,雄性恒河猴的 FSH、L H和睾酮分泌水平明显偏低。在生殖季节 ,雄性恒河猴的 FSH、L H和睾酮分泌水平显著升高。揭示雄性恒河猴的生殖功能存在季节性变化     

Effect of semen collection frequency on seasonal variation in sexual behaviour,testosterone, testicular size and semen characteristics of tropical hair rams (<Emphasis Type="Italic">Ovis aries</Emphasis>)

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.