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.     

高温对荷斯坦种公牛精液品质及精清生化指标的影响研究

以荷斯坦种公牛为试验牛研究了高温对其精液品质和精清生化指标的影响。结果表明:(1)高温可造成种公牛精液品质显著下降。使原精活力、精子密度、活精子百分数和顶体完整率分别比春季下降3·13%(P<0·05)、34·8%(P<0·01)、15·0%(P<0·01)和17·8%(P<0·01),精子畸形率比春季上升25·5%(P<0·01)。(2)夏季荷斯坦种公牛精清睾酮含量仅为4·31pg/mL,极显著低于非高温季节(P<0·01)。(3)高温环境使得荷斯坦种公牛精清钾、钙、镁处于最低水平(P<0·01),精清碱性磷酸酶(ALP)、酸性磷酸酶(ACP)处于最高水平(P<0·01),使精清钠由春季至夏季呈显著下降趋势。     

Tunica dartos index as a parameter for measurement of adaptability of rams to subtropical conditions of Egypt

The aim of the present study was to investigate the effects of hot summer climatic conditions (compared to winter) on the libido, semen quality traits, level of serum testosterone hormone and some physiological and body measurements of Egyptian Suffolk rams. A parameter for the tolerance of the rams to adverse hot climatic conditions, designated as the tunica dartos index (TDI), was estimated as the multiplication of the percentage change in scrotal length and that of the percentage difference between rectal temperature and scrotal skin temperature. The relationships between the TDI and semen characteristics were also estimated. The results showed that in summer, the reaction time, pH, percentage dead and abnormal spermatozoa, acrosomal damage and temperatures of rectum, body skin and scrotal skin and scrotal length were significantly higher, while sperm motility, sperm concentration, scrotal circumference and testis length were significantly lower than in winter. The correlation coefficient (r) values estimated between the TDI and each of the semen pH, ejaculate volume, sperm motility and sperm cell concentration were positive, and those estimated between the TDI and each of the reaction time, dead and abnormal spermatozoa and acrosomal damage were negative. The best values of libido (low reaction time), semen pH, semen motility percentage, sperm cell concentration and testosterone level were recorded with a high TDI level (7.5 and more), while those of percentage of dead spermatozoa, sperm abnormalities and acrosomal damage were recorded with a low TDI level (less than 4.5). It can be concluded that the TDI correlates well with the reproductive ability of the ram and can be a reliable parameter to indicate the tolerance of rams to hot subtropical conditions in Egypt.     

Monthly changes in some reproductive parameters and in testosterone and thyroxine values of rams throughout one year under continental climate conditions

Ten sexually mature rams were used in this study. Blood and semen was collected monthly from rams for one period of 12 months to study semen characteristics and to determine serum testosterone and thyroxine (T4) hormones. Results showed that all of the rams are continuous breeders as they show sexual desire and produce semen throughout the whole year. However, monthly variations in reproductive and semen characteristics were detected. Relative testes volume, ejaculate volume, sperm motility, sperm concentration and serum testosterone levels were higher during autumn months than at other months of the year. In addition, autumn months showed moderate percentage of abnormal spermatozoa. Furthermore, serum T4 was significantly higher in summer and autumn months than that observed in winter and spring. These results indicate that ram semen quality in Afyon continental climate conditions may be better during late summer and early autumn months than during other months of the year.     

Estimation of Genetic Parameters and Analysis of Season Effects and Age Effects for Semen Traits in Landrace Boars

The purpose of this study was to estimate the genetic parameters of semen traits of Landrace boars in South China and to analyze the influence of the age and season of semen collection on semen traits, so as to provide theoretical basis for formulating reasonable boar breeding program. The Asreml-R was used to analyze the 107 221 semen data of 1 605 Landrace boars from 2 AI stations in Southern China, the single-trait repeatability animal model was used to estimate the variance components, heritability and repeatability of each semen traits, two-trait repeatability animal model was used to estimate genetic correlation and phenotypic correlation of semen volume, semen density, sperm motility and percentage of abnormal sperm. The general linear model of R language program was used to analyze the influence of age and season of semen collection on semen traits. The results showed that the semen volume and percentage of abnormal sperm had medium heritability (0.23 and 0.38), and the variation coefficient of percentage of abnormal sperm was 85.42%, while the other traits had low heritability (0.07-0.19). Semen volume-semen density and sperm motility-percentage of abnormal sperm had extremely significantly negative genetic correlation(-0.77 and -0.90, respectively). Semen density-sperm motility showed extremely significantly positive genetic correlation (0.50). The influence of the age of semen collection on semen traits was significant(P<0.05). After boars reached sexual maturity, semen volume showed a significant increase, semen density and percentage of abnormal sperm showed a general decrease, and total sperm number and functional sperm number were significantly higher in the 13-18-month of age group than those in the other groups (P<0.05). The semen density was the highest in spring, and the total sperm number and functional sperm number were significantly higher in autumn and winter than those in spring and summer (P<0.05). In conclusion, the semen volume and percentage of abnormal sperm of Landrace boars can be selected as candidate traits. In the boar production management, boar whose semen production after 36 months of age decline, will be considered to update. Boar semen quality was significantly higher in autumn and winter than those in spring and summer. It is suggested that cooling work should be done in advance in Southern China in summer.     

长白公猪精液性状遗传参数评估及采精月龄和季节因素分析

旨在估计华南地区长白种公猪精液性状遗传参数以及分析公猪采精月龄和季节对精液性状的影响,为合理制定种公猪育种方案提供理论依据。本研究采用Asreml-R对华南地区两个公猪站1 605头长白公猪107 221条精液数据进行统计分析,利用单性状重复力动物模型估计公猪精液各性状的方差组分、遗传力和重复力,利用两性状重复力动物模型对精液体积、精液密度、精子活力和精子畸形率等性状进行遗传相关和表型相关估计;利用R语言程序中的一般线性模型分析采精月龄和季节对精液性状的影响。结果表明,精液体积和精子畸形率属于中等遗传力（0.23和0.38）,其中精子畸形率的变异系数较大,为85.42%,其余性状都为低遗传力（0.07~0.19）;精液体积与精液密度以及精子活力与精子畸形率为极显著遗传负相关（-0.77和-0.90）;精液密度与精子活力呈极显著的遗传正相关（0.50）。采精月龄对精液性状影响显著（P<0.05）,在公猪达到性成熟后,精液体积呈显著上升趋势,精液密度和精子畸形率总体呈下降趋势,精子总数和有效精子数在13~18月龄组显著高于其他组（P<0.05）。在春季精液密度最高,精子总数和有效精子数在秋、冬季显著优于春、夏季（P<0.05）。综上,长白公猪精液体积和精子畸形率具有较大的选育潜力,可作为候选性状进行选择。在公猪生产管理方面,公猪36月龄后精液产量下降,考虑更新淘汰。公猪精液品质在秋、冬季显著优于春、夏季,在中国南方夏季应提前做好降温工作。     

Determination of the relationship between sperm morphologic classifications and fertility in stallions: 66 cases (1987-1988)

The analysis of breeding records and sperm morphologic classifications from ejaculated semen during 99 stallion seasons, over a 2-year period, revealed a significant correlation (r = 0.34, P less than 0.01) between the percentage of morphologically normal sperm in ejaculates and the per cycle fertility estimate of the stallions studied. In addition, the percentage of sperm classified as having major defects (abnormal heads, proximal droplets, and abnormal midpieces) was significantly inversely correlated (r = -0.36, P less than 0.01) with the same fertility estimates. Multiple variable regression demonstrated that the variation in 2 morphologic features classified as major defects, abnormal heads, and proximal droplets, accounted for the largest amount of variation in fertility. It appears that in stallions, a large percentage of ejaculated sperm with major defects or other defects in combination with major defects is associated with a larger reduction in fertility than is associated with other defects.     

不同季节肉用种公牛精液品质与生理常值、血清及精清生化指标相关关系研究

以利木赞和夏洛来种公牛为试验牛，研究不同季节对其精液品质、冻精产量、生理常值、血清及精清生化指标的影响。结果表明：（1）与其它季节相比，夏季肉用种公牛的原精活力、冻精活力、活精于百分数、顶体完整率均显著降低，而精于畸形率显著升高（P〈0．05）。精子密度以秋季最低。（2）冻精产量夏季处于最低水平，平均每月仅为7388支。（3）夏季肉用种公牛的血清LH、睾酮、T3、皮质醇的含量分别为48．12、4．15、1．11、4．89ng／L，显著低于春、秋、冬季（P〈0．01）。（4）夏季肉用种公牛血清钠、钾、钙、镁均处于最低水平，显著低于其它季节（P〈0．01）。（5）夏季肉用种公牛精清睾酮水平明显下降，显著低于春季、秋季和冬季。（6）精清钠、钾、钙夏季含量最低，分别为83．12mmol／L、18，77mmol／L和4．63mmol／L；精清镁含量由春季至秋季呈显著下降趋势；精清磷含量夏季最高，为4．65mmol／L，显著高于春季、秋季和冬季。（7）肉用种公牛精清ALP夏季含量为1784．3U／L，显著高于春、秋两季，但低于冬季。（8）精清睾酮与精液品质各指标存在显著相关；血清生化指标与精清生化指标存在显著相关；直肠温度、呼吸频率与精液品质及血清生化指标存在显著相关性，与精清生化指标相关性不大。     

Seasonal changes in semen characteristics, composition of seminal plasma and frequency of acrosome reaction induced by calcium and calcium ionophore A23187 in Large White boars

This study attempted to explain the mechanisms regulating boar fertility by examining seasonal changes in semen characteristics, the composition of seminal plasma and responsiveness of sperm acrosomes to Ca(2+) and the Ca(2+) ionophore A23187 (Ca(2+)/A23187). Sperm-rich and sperm-poor fractions were separately collected from 3 mature fertile Large White boars once a month over a one-year period. During the period of study, ambient temperature and relative humidity were recorded for within the stall in which the boars were kept and the semen characteristics, composition of the seminal plasma of sperm-rich fractions, and occurrence of the acrosome reaction in response to Ca(2+) (3 mM)/A23187 (0.3 microM) were examined. The highest mean maximum and minimum ambient temperatures were recorded in August-September, whereas the lowest mean maximum and minimum ambient temperatures were recorded in December and January, respectively. There was a moderate peak in relative humidity from July to October. The lowest percentages of motile spermatozoa and of spermatozoa with intact acrosomes and highest percentage of spermatozoa with abnormal morphology and strongest agglutination were seen in August-September. The total protein and albumin concentrations were lowest in August-September. Testosterone levels increased gradually as day length decreased after the summer solstice (June) and peaked in October-November. The percentage of acrosome reactions in response to Ca(2+)/A23187 was highest with the quickest response in August-September, as shown by the shortest time required for 50% of relative acrosome reactions. The farrowing rates were lowest in these same 2 months. These results suggest that seasonal infertility in Large White boars may be due, at least in part, to a combination of low motility, abnormal morphology including acrosomal abnormality, and early occurrence of the acrosome reaction in response to stimulus, possibly resulting from a decrease in acrosomal stabilizing proteins in the seminal plasma during summer. These changes may be modulated by heat/humidity stress and/or photoperiod-regulated testosterone.     

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.     

Therapeutic effect of frequent injections of GnRH analogue in a beagle with knobbed acrosome abnormality of sperm

A Beagle dog (3 years old) that ejaculated high percentages (mean ± SE: 29.1 ± 1.2%) of sperm with a knobbed acrosome abnormality and a low number of sperm and that also had a low plasma testosterone (T) level was given 10 subcutaneous injections of 1 μg of gonadotropin-releasing hormone analogue (GnRH-A) at 3-day intervals. The plasma T level and number of sperm increased 12-14 weeks after the first injection. Although the percentages of sperm with knobbed acrosome abnormality did not change after the GnRH-A therapy, the number of sperm and percentage of actively motile sperm increased after the therapy, and a bitch gave birth to 5 healthy puppies after intravaginal artificial insemination with fresh semen collected 14 weeks after the first injection.     

Alleviation of reproductive toxicity of gossypol using selenium supplementation in rams

The objective of this study was to evaluate the reproductive toxicity of gossypol and the possible counteracting effect of selenium supplementation in rams. Twenty-five mature crossbred (Barki × Rahamni) rams were randomly divided into 5 equal groups. The first group served as a control (no gossypol in diet). The second and third groups received diets containing free gossypol of 9 and 14 mg·kg(-1) BW·d(-1)(low level and high level of gossypol), respectively. The fourth and fifth groups received the same diets given to the second and third groups, respectively, with an oral administration of 1 mg selenium (as sodium selenite) daily for each animal. Results showed reductions in ejaculate volume (P = 0.028), percentage of dead sperm (P = 0.003), total functional sperm fraction (P < 0.001), and blood serum concentration of testosterone (P < 0.001) in the presence of both levels of gossypol inclusion. Furthermore, high level of gossypol reduced forward motility (P < 0.001) and semen initial fructose concentration (P = 0.002) and increased abnormal-head sperm (P = 0.003) and blood serum concentration of triiodothyronine (P = 0.006). Regardless of selenium supplementation, increasing level of free gossypol in diet resulted in a significant decrease in the percentage of forward motility (P = 0.037) and significant increases in the mean values of sperm concentration (P < 0.001), total sperm output (P = 0.002), percentage of total abnormal sperm (P = 0.058), and abnormal-head sperm (P = 0.016). On the other hand, regardless of levels of gossypol inclusion, selenium supplementation resulted in significant increases in libido (P < 0.001), mean values of ejaculate volume (P < 0.001), percentage of forward motility (P = 0.019), total sperm output (P < 0.001), total functional sperm fraction (P < 0.001), semen initial fructose concentration (P = 0.031), and blood serum concentrations of both testosterone and triiodothyronine (P < 0.001). In conclusion, free gossypol in diet induced adverse effects on semen quality in rams, but selenium supplementation successfully counteracts most of the hazardous effects of gossypol on semen characteristics.     

The effect of some exogenous hormones on seminal characteristics, libido and peripheral plasma testosterone concentrations in the male Beagle

The effect of short term treatment with exogenous hormones viz. HCG, testosterone, betamethasone and delmadinone, on semen characteristics, libido and peripheral plasma testosterone concentrations was studied in five mature Beagle dogs. HCG caused a slight increase in the total ejaculatory volume whilst betamethasone depressed the total ejaculatory volume, reduced sperm output and increased the number of abnormal spermatozoa. Delmadinone reduced libido, ejaculatory volume and total sperm output.     

Fluctuation in the concentration of sex steroids and aflatoxin B1 in the seminal plasma of boars and its relation to sperm production

The concentration of testosterone, 17-beta oestradiol and aflatoxin B1 were studied in the semen plasma of 21 boars of four breeds for the period of twelve months. The following spermiological parameters were investigated: semen volume, sperm concentration, percentage of abnormal spermatozoa, and survival of spermatozoa. The fertilizing capacity of ejaculates was evaluated according to the conception rate of sows and gilts after the first insemination, according to the average number of piglets per litter and average number of live-born piglets per litter. The highest aflatoxin B1 residues in sperm were recorded in March to May and were related with aflatoxin concentration in feed ration. The group of boars with fertility disorders had more aflatoxin in their sperm (up to 100 pmol . l-1), lower sperm concentration, lower survival of spermatozoa, and a larger proportion of abnormal spermatozoa. The year season had a significant influence on the concentration of the hormones. The highest average value of testosterone (10.2 +/- 1.28 nmol) was obtained in autumn and lower values were recorded in winter. The changes in 17-beta estradiol concentration were similar to the changes in testosterone content, with the maximum value in November (0.249 nmol X 1(-1]. The boars with reproduction disorders had a significantly lower concentration of 17-beta oestradiol. Significant correlations were found between the concentration of the hormones, semen volume, and sperm concentration. 17-beta oestradiol also had a significant positive correlation to abnormal spermatozoa and to the activity of aspartate aminotransferase.     

Plasma Hormone Levels and Semen Quality in Male Cats during Non-Breeding and Breeding Seasons

Female cats are known to be seasonal breeders and male cats annual breeders. Despite this, there are limited data on the influence of breeding season (BS) on hormone concentration and semen quality in the male cat. This study compared plasma concentrations of LH and testosterone (T), and semen quality during the non-breeding season (NBS) and BS in five male cats subject to natural hours of daylight but a constant environmental temperature. Plasma LH and T concentrations were higher during the BS in 2/35 and 3/5 cats, respectively, although when comparing both hormones combined, values were higher during the BS than the NBS in all cats (p < 0.01). There were no significant differences in the percentage of abnormal sperm between the cats. Overall, semen quality was superior during the BS with larger semen volume in 2/5, sperm motility in 2/5 and sperm viability in 3/5 cats. Although there was a clear seasonal effect on hormone secretion and semen quality, during the NBS all cats were likely to have been fertile.     

公火鸡外周血浆促黄体激素、睾酮浓度的变化及其与精液品质相关性的研究

8只公火鸡自然光照下饲养,每隔10d收集一次血样和精样,连续5个月(6-10月份)。用放射免疫法测定外周血浆的促黄体激素及睾酮浓度,并用常规方法估测精液品质。结果表明,血浆LH浓度从6月上旬到10月下旬逐步降低,其与白昼长度及湿度呈显著的相关性(r分别为0.553和-0.586)。血浆睾酮浓度的变化趋势与LH相似,血浆睾酮浓度与LH浓度、白昼长度呈显著的相关性(r分别为0.747和0.953)。射精量的变化与白昼长度的变化一致,相关系数为0.655。本实验还表明,LH与射精量呈弱正相关,而与精子密度和死亡精子百分数呈中等强度正相关(r分别为0.368、0.591和0.553)。睾酮浓度与精液品质指标皆呈弱正相关。公火鸡换羽时,血浆LH浓度、射精量,精子密度及死亡精子百分数显著低于非换羽期,睾酮浓度没有发生明显的变化。     

A comparison of electro-ejaculation with the artificial vagina for ram semen collection

Nine fertile three-year-old Romney rams were ejaculated both by means of electro-ejaculation and by the artificial vagina. The ram repeatabilities of semen volume, concentration, total sperm number, percentage normal sperm and wave motion score of ejaculates collected by electro-ejaculation were 0.17, 0.08, 0.12, 0.61 and 0.23 respectively compared with the repeatabilities of ejaculates collected by the artificial vagina of 0.28,0.79, 0.56,0.72 and 0.54. The repeatability results showed that it was possible to rank rams on the quantity of sperm produced in a single ejaculate obtained by an artificial vagina, but not on the quantity obtained by electro-ejaculation. The correlation co-efficients between the ram means for the two techniques were for volume 0.05, concentration 0.06, total sperm number -0.21, percentage normal sperm 0.73, and wave motion score 0.35. Only the percentage normal sperm coefficient was significant.     

Estimation of genetic parameters and genome scan for 15 semen characteristics traits of Holstein bulls

A QTL detection experiment was performed in French dairy cattle to search for QTL related to male fertility. Ten families, involving a total of 515 bulls, were phenotyped for ejaculated volume and sperm concentration, number of spermatozoa, motility, velocity, percentage of motile spermatozoa after thawing and abnormal spermatozoa. A set of 148 microsatellite markers were used to realize a genome scan. First, genetic parameters were estimated for all traits. Semen production traits were found to have moderate heritabilities (from 0.15 to 0.30) while some of the semen quality traits such as motility had high heritabilities (close to 0.60). Genetic correlations among traits showed negative relationships between volume and concentration and between volume and most quality traits such as motility or abnormal sperm while correlations between concentration and these traits were rather favourable. Percentages of abnormal sperm were negatively related to quality traits, especially with motility and velocity of spermatozoa. Three QTL related to abnormal sperm frequencies were significant at p < 0.01. In total, 11 QTL (p < 0.05) were detected. However, the number of QTL detected was within the range of expected false positives. Because of the lack of power to find QTL in this design further analyses are required to confirm these QTL.     

Reproductive function of Hungarian Mangalica boars: effect of seasons

Seasonal changes in testis volume, testosterone (T) productivity (GnRH test) and semen characteristics of Mangalica boars were studied. The biggest testis volume was measured in autumn and the smallest in winter. Significant differences were demonstrated between autumn-winter (P = 0.012) and autumn-spring (P = 0.015) in testis volume. The highest basic T concentration (Tb) was observed in autumn and the lowest in summer. The provoked T concentration (Tincr) was significantly higher in autumn than in spring (P = 0.0007). A strong correlation was observed between T concentrations and testis volume in spring. The highest ejaculate volume was measured in winter while the lowest in autumn. Significant differences were found in semen concentration as well as in the total number of spermatozoa per ejaculate between seasons. The highest number of abnormal sperm cells was observed in spring while the lowest in summer. It can be concluded that the ejaculate of the Mangalica breed tends to be of lower volume and higher sperm concentration as compared to most pig breeds. Seasonal differences could be observed in testicular measurements, testosterone production capacity and sperm morphological features; however, sperm motility remained constantly high during the study.     

Exploratory analysis of differences in sperm morphology in Nelore and Gir (Bos indicus) bulls

The aim of this study was to evaluate the effects of breed and season on semen quality parameters of zebu bulls. Data (1,632 registers) of semen production from Gir (n?=?4) and Nelore (n?=?15) bulls were collected between October 2005 and November 2009. The ejaculates were collected twice a week during various seasons (summer, fall, winter, and spring) and evaluated for the following semen parameters: ejaculate volume, sperm concentration, sperm motility, forward progressive motility (FPM), and sperm morphology. Factor analysis was used to determine the relationship among variables. The effect of breed (Gir and Nelore) and season and their cross effect on each parameter and extracted factor were tested using ANOVA. A negative correlation (P?<?0.05) was observed between FPM and proximal droplet, as well as with abnormal loose head, abnormal small head, pouch formation, abnormal mid-peace, and strongly folded tail. Gir bull sperm showed more major defects, detached acrosome, and minor FPM (P?<?0.01), whereas Nelore bulls showed a higher number of sperm with normally loose head.