Pregnancy Rates in Lactating Holstein–Friesian Cows after Artificial Insemination with Sexed Sperm

The effects of artificial insemination (AI) using sexed sperm on pregnancy rates have seldom been studied in lactating dairy cows on commercial dairy farms. We evaluated pregnancy results after AI of 306 lactating dairy cows, of which 157 were inseminated with 2x10(6) frozen/thawed sexed sperm and 149 with 15x10(6) frozen/thawed unsexed sperm. The average pregnancy and calving rates were 21.0% and 20% for the sexed-sperm AIs and 46% and 45% for the unseparated control-sperm AIs respectively (p<0.001). The proportion of female calves derived from sexed-sperm AI was 82% compared with 49% for control AI (p<0.01). The proportion of live and healthy calves in single births was 100% for sexed-sperm AI and 97% for control AI (p>0.05). Our results indicate that AI with low-dose sexed sperm under field conditions in commercial dairy herds without oestrus synchronization results in significantly reduced pregnancy rates compared with normal-dose AI. Improved insemination strategies combined with increased sperm doses are needed before the use of sexed sperm can be of any significant benefit for the dairy and beef industry.     

Genome‐Wide Association Study for Sperm Concentration in Holstein‐Friesian Bulls

The aim of the study was to screen the entire bull genome to identify markers and candidate genes underlying sperm concentration. The analysed data set originates from a population of 877 Polish Holstein‐Friesian bulls. Based on sperm concentration value, two extreme groups of bulls were created: Low (L, n = 126) and High (H, n = 140). Each bull was genotyped using the Illumina BovineSNP50 BeadChip. Genome‐wide association analysis was performed with the use of GoldenHelix SVS7 software. An additive model with a Cohran–Armitage test, Correlation/Trend adjusted by a Bonferroni test, was used to estimate the effect of SNP marker for sperm concentration. Thirteen markers reached genome‐wide significance. The most significant SNPs were located on chromosome 3 (rs109154964 and rs108965556), 14 (rs41621145) and 18 (rs41615539), in the close vicinity of protein arginine methyltransferase 6 (PRMT6), Sel1 repeat containing 1 (SELRC1), triple QxxK/R motif containing (TRIQK) and zinc finger homeobox 3 (ZFHX3) genes, respectively. For three other candidate genes located close to significant markers (within a distance of ca 1 Mb), namely histone deacetylase 9 (HDAC9), an inhibitor of DNA binding 2 (ID2) and glutathione S‐transferase theta 1 (GSTT1), their potential role in the production of male germ cells was confirmed in earlier studies. Six additional candidate genes (Vav3, GSTM1, CDK5, NOS3, PDP1 and GAL3ST1) were suspected of being significantly associated with sperm concentration or semen biochemistry. Our results indicate the genetic complexity of sperm concentration but also open the possibility for finding causal polymorphism useful in marker‐assisted selection.     

应用计算机辅助精子质量分析系统对猪常温精液的品质检验

计算机辅助精子质量分析(computer-assisted sperm analysis,CASA)系统具有快速、客观、精确等特点,与传统人工分析法相比具有明显的优势。实验选择3个品种9头公猪的精液,采用计算机辅助分析法和人工分析法同时分析精液密度和活力,比较两种方法的差异。CASA采用伟力彩色精子质量检测系统(WLJY-9000),人工分析法采用《种猪常温精液》(GB23238-2009)规定的方法。结果表明,CASA法和人工分析法对精子密度的检测结果差异不显著(P0.05),对杜洛克和大白公猪精子活力的检测差异不显著(P0.05)。CASA与人工分析法对精液密度和活力的检测结果较为一致,CASA更能体现精子的运动状态,对畸形率的观测更为清晰。     

广州地区娟姗公牛与荷斯坦公牛精液品质的比较研究

本试验选择亚热带气候条件下广州地区的娟姗公牛和荷斯坦公牛各5头,比较两个品种公牛的精液品质(采精量、原精密度、原精活力、细管精液产量、冻后活力、低渗膨胀率及穿透率)。研究表明,荷斯坦公牛每次采精的采精量(16.14±0.06 mL)和细管精液产量(189.17±3.11支)都极显著地高于娟姗公牛(4.74±0.05 mL,158.46±2.64支)(P<0.01);娟姗公牛的原精密度(8.95±0.08亿/mL)极显著地高于荷斯坦公牛(8.32±0.07亿/mL;P<0.01);娟姗公牛原精活力(0.731±0.004)高于荷斯坦公牛(0.729±0.003),但两者差异不显著(P<0.05);娟姗公牛精液的冻后活力(0.355±0.003)极显著高于荷斯坦公牛(0.339±0.003;P<0.01);娟姗公牛冷冻精液的低渗膨胀率(34.50%±0.49%)显著高于荷斯坦公牛(31.21%±0.59%;P<0.01);娟姗公牛冷冻精液对去透明带仓鼠卵的穿透率(84.51%±13.83%)显著高于荷斯坦公牛(81.52%±6.13%;P<0.05)。     

奶牛性控冻精和常规冻精活力对比试验分析

试验观测对比奶牛性控冻精和常规冻精解冻后精子存活时间,为进一步把握输精时间,提高受胎率提供依据。试验结果表明:性控冻精刚解冻时活力较高,为0.5级以上,但活力下降快、存活时间较短,解冻后6h活力降低为零;常规冻精刚解冻时活力在0.4～0.5级之间,但存活时间较长,活力下降速度慢,解冻后8h活力降低为零。所以性控冻精解冻后,要求输精技术员尽快输精。     

Comparison between the Sperm Morphology in Semen Samples Obtained from Yearling Beef Bulls by Transrectal Massage of the Ampullae and Cauda Epididymal Dissection

As electroejaculation (EEJ) is prohibited for use on unanaesthetized animals in Sweden, there is a need for an alternative method of semen collection from bulls in the field. The aim of the present study was to evaluate the use of transrectal massage (TM) of the ampullae to collect semen from yearling beef bulls under field conditions in Sweden. Transrectal massage was performed on 52 yearling beef bulls. Volume of semen collected, duration of procedure, percentage progressively motile sperm, and sperm concentration were measured. Smears were prepared for sperm morphology examination. Semen samples were obtained from 47 of 52 bulls. Mean volume was 3.2 ml (SD +/- 3.7), mean duration of collection was 7.4 min (SD +/- 2.8), mean percentage progressively motile sperm was 43.5% (SD +/- 29.2) and mean concentration was 201.9 x 10(6) spermatozoa/ml (SD +/- 278 x 10(6)). Twenty-three of the 52 bulls were slaughtered 3-4 days after semen collection and aliquots of the cauda epididymal contents were collected for sperm morphology examination. The percentages of proximal droplets, abnormal tails and abnormal midpieces were significantly higher (p < 0.05) and the percentage of detached heads was significantly lower (p < 0.05) in the post-mortem samples compared with those in the TM samples. However, importantly there was no significant difference between the two sample types in the percentages of abnormal heads. This study demonstrates that semen can be collected from yearling beef bulls by TM. We think that TM constitutes a useful tool, when semen collection with EEJ or artificial vagina (AV) is not possible under field conditions, when included in the bull breeding soundness evaluation (BBSE) protocol. However, further studies are needed, and presently being carried out, to evaluate if semen samples collected by TM are comparable with semen samples collected by AV.     

Genetic Parameters for Semen Production Traits in Austrian Dual-Purpose Simmental Bulls

Genetic parameters were estimated for semen production traits collected in an Austrian AI centre in the years 2000-2004. In total, 12,746 ejaculates from 301 Austrian dual-purpose Simmental (Fleckvieh) AI bulls were examined considering different effects on ejaculate volume, sperm concentration, percentage of viable spermatozoa in the ejaculate, total spermatozoa per ejaculate and motility. The model for genetic parameter estimation included the fixed effects age of bull, collection interval, number of collections on collection day, bull handler, semen collector, year and month of collection, a random additive genetic component and a permanent environmental effect. Correlations between estimated breeding values for semen traits and male fertility from the routine evaluation were calculated. The fertility trait considered in the routine evaluation is non-return rate 90 for the first insemination. All semen production traits were moderately heritable. Heritabilities for volume, concentration, percentage of viable spermatozoa, total number of spermatozoa and motility were 0.18, 0.14, 0.10, 0.22 and 0.04, respectively. Correlations between breeding values for semen quality traits and routinely estimated breeding values for male fertility were low and ranged from 0.08 to 0.17 indicating that semen production traits are rather poor predictors of male fertility.     

Functional Sperm Parameters and Fertility of Bull Semen Extended in Biociphos-Plus® and Triladyl®

Twenty ejaculates from five dairy AI‐bulls were used to compare, in a split‐sample experiment, the fertility [56 day‐non‐return‐rate (NRR) from more than 14000 AI) and sperm viability post‐thaw of semen diluted with an egg yolk‐ (Triladyl®) or soybean‐based (Biociphos‐Plus®) commercial extender. The in vitro evaluations were divided in two experiments. Experiment 1 (n = 20) included post‐thaw evaluations of motility (subjective and computerized), membrane integrity (CalceinAM/EthD‐1, SYBR‐14/PI, and osmotic resistance test; ORT), and capacitation status (CTC/EthD‐1). Experiment 2 (n = 10) included evaluations of the capacitation‐(CTC/EthD‐1) and acrosome status (FITC‐PSA/EthD‐1) during incubation with/without a challenge with solubilized zona pellucida proteins (SZP). No significant difference in the fertility (69.1 ± 0.8 versus 69.2 ± 0.8) results was found between the two extenders. In experiment 1, the computerized motility evaluations post‐thaw (CASA) showed higher values for Biociphos‐Plus® processed semen for the velocity patterns and lateral sperm head displacement. After 6 h at room temperature (20–22°C) all the CASA motility patterns were significantly higher for Biociphos‐Plus®. The proportion of spermatozoa with intact membranes assessed by CalceinAM was significantly higher in Biociphos‐Plus® (p < 0.001) compared to Triladyl®, but such difference was not seen when using SYBR‐14 or the ORT‐assay. When using the CTC/EthD‐1 assay, a lower proportion of acrosome reacted (AR) spermatozoa post‐thaw (p < 0.01) was found in Biociphos‐Plus® processed semen, as well as a tendency (p < 0.07) for a higher number of uncapacitated spermatozoa. In experiment 2, the proportion of uncapacitated spermatozoa was significantly higher for Biociphos‐Plus® when semen was incubated (38°C and 5% CO₂) without SZP at both 0 (p < 0.001) and 30 min (p < 0.05). Concomitantly, Triladyl® showed a higher percentage of capacitated spermatozoa at 0 (p < 0.01), 30 (p < 0.05) and 120 min (p < 0.05). A higher (p < 0.05) incidence of AR‐spermatozoa was seen in Triladyl® at the beginning of the incubation with SZP. No significant difference between extenders was detected for the acrosome status by the FITC‐PSA‐assay. Incubation with SZP induced acrosome reaction of capacitated spermatozoa in both extenders, which was detected by CTC and FITC‐PSA assays. In conclusion, fertility was not affected by Biociphos‐Plus® when 15 × 10⁶ of spermatozoa per AI dose were inseminated. The finding that higher frequencies of spermatozoa seemed more membrane stable post‐thaw, when frozen in Biociphos‐Plus®, might indicate that this extender better protects the sperm viability compared with Triladyl®.     

Pulmonary surfactant from healthy Belgian White and Blue and Holstein Friesian calves: biochemical and biophysical comparison

The biochemical composition and biophysical behaviour of pulmonary surfactant samples isolated from healthy Belgian White and Blue (BWB) and Holstein Friesian (HF) calves have been investigated and compared. Interesting differences in composition have been demonstrated. In particular, a higher level of total hydrophobic surfactant-associated proteins (SP) (due to higher levels of SP-B and SP-C) is reported in HF calves compared to BWB calves. Higher levels of phosphatidylcholine (PC) and especially the disaturated form of PC were also found in HF as compared to BWB calves. No immediate effect on the surface tension properties evaluated by the pulsating bubble surfactometer was found between the surfactant samples of the two breeds under physiological conditions. However, since a high content of disaturated PC and the presence of the SP-B and SP-C are thought to be essential for the surface activity, we propose that the reported modifications could contribute to the apparently lower resistance of the BWB calves to respiratory troubles in comparison with HF calves.     

Influence of Random Factors and Two Different Staining Procedures on Computer-assisted Sperm Head Morphometry in Bulls

Contents Computer-assisted sperm analysis has the potential to improve reproducibility and objectivity in the assessment of sperm morphology. The aim of this study was to evaluate the use of a computer-assisted sperm morphometry analysis system for the determination of sperm head dimensions in bulls. Two experiments were performed to determine the variability caused by random factors and the influence of two different staining procedures. In the first experiment, three ejaculates were collected from each of five clinically healthy bulls. Air-dried semen smears were stained using a modified Farelly staining. The slides were observed via bright field microscopy with green filter using a 100× oil immersion objective. A video camera attached to the microscope transmitted images to a personal computer. Each sperm head was identified and analysed by the computer software (Morphology Analyzer V. 1.5; Mika Medical GmbH, Ismaning, Germany). Area, length and width of each sperm head were calculated and stored in a database for further statistical analysis. A minimum of 100 sperm heads were evaluated per slide. In experiment 2, the influence of two different staining procedures (Farelly and Papanicolaou) on sperm head dimensions was determined. The mean spermatozoal head measurements across all slides for area, length and width were 40.49 μm², 9.70 μm and 5.30 μm, respectively. On the basis of these results, the variability between slides, ejaculates and bulls using variance component estimation was calculated. All random factors (bull, ejaculate and slide) had a significant effect (p < 0.001) on sperm head dimensions. However, the variability attributable to bull (18.89–51.72%) was considerably higher compared with that of slide and ejaculate (0.17–5.27%). Additionally, differences existed between bulls concerning the shape and normality of histograms of their sperm head dimensions. The minimum number of spermatozoa required for analysis of sperm head dimensions was found to be about 60 spermatozoa per sample. The use of Papanicolaou stain resulted in significantly smaller sperm head dimensions, e.g. sperm head area 31.48 versus 38.35 μm² (p < 0.001). In conclusion, computer-assisted sperm head morphometry provides an objective, precise and reproducible tool. Comparisons of results from different studies should consider the influence of random and experimental factors to avoid misinterpretation.     

Repeatability and Heritability of Ovulation Number and Embryos in Dam-daughters Pairs in Superovulated Holstein–Friesian Cows

Holstein-Friesian dams (n = 28) and daughters (n = 28) were superovulated (total number of observations was 235) to determine the repeatability and heritability of ovulation number and embryo collection result for FSH treatment. The donor cows were superovulated with FSHp, artificial insemination was performed and embryo collection was carried out 7 days later. For the analysis, the raw corpdata of the number of corpora lutea (CL), the number of collected embryos (EM) and their log-transformed values were used (log CL, log EM). The genetic parameters were calculated by using the VCE4 software. For calculating heritability, the number of embryo collection was used as a random effect; for calculating repeatability, the permanent environment was fitted. The additive genetic variance of CL was 8.91 and that of the EM was 9.23. The additive genetic variance for the log CL and log EM were 0.457 and 0.340, respectively. The estimated heritability for CL and EM were 0.234 and 0.159, and repeatability were 0.386 and 0.301, respectively. Higher heritabilities but lower as the previous repeatabilities were observed for the log-transformed data, 0.266, 0.194 and 0.294, 0.208 for log CL and for log EM, respectively.     

Association Between ETFA Genotype and Activity of Superoxide Dismutase,Catalase and Glutathione Peroxidase in Cryopreserved Sperm of Holstein–Friesian Bulls

The aim of this study was to determine whether C/T missense mutation within the ETFA gene is associated with sperm antioxidant enzymatic activity. One hundred and twenty Holstein–Friesian bulls were genotyped by the PCR‐RFLP technique (MwoI). Commercial straws of frozen‐thawed semen were used to evaluate the activity of three antioxidant enzymes: superoxide dismutase, catalase and glutathione peroxidase. Among all bulls investigated, genotype CT was the most frequent (44.2%), in comparison with CC (42.5%) and TT (13.3%). Significant differences in glutathione peroxidase activity were observed between homozygous individuals (CC vs TT) with heterozygous CT having intermediate values. Dismutase activity was significantly associated with ETFA genotype, although only bulls with the CT genotype were significantly different from bulls carrying the CC genotype. The activity of catalase showed a similar trend (but was not statistically significant). In conclusion, we found that bulls with the ETFA TT genotype produce sperm with the highest glutathione peroxidase activity and can therefore be more efficiently protected from reactive oxygen. The mechanism of this interaction needs to be elucidated in future research.     

Assessment of Different Sperm Quality Parameters to Predict in vitro Fertility of Bulls

Frozen‐thawed semen from six bulls with high (> 60%) and low (20–35%) in vitro fertility was used for studying the predictive value of simple sperm quality tests with respect to in vitro fertilization (IVF) outcome as assessed by pronucleus (PN) formation ability. Sperm quality parameters, such as sperm concentration, motility, progressive motility, live‐dead sperm ratio, morphology, membrane integrity, mitochondrial activity and acrosomal status were analysed using both conventional and automatic techniques at three time points during the IVF process, namely after sperm thawing, Percoll differential gradient centrifugation and IVF. Associations between the sperm quality parameters before and after IVF, and PN formation ability were assessed by using linear regression analyses. The percentages of motility, progressive motility and normal morphology determined after sperm thawing, and the percentage of live spermatozoa assessed after Percoll preparation by using nigrosin‐eosin (N‐E) staining showed a good correlation with PN formation ability, but the regression parameters were borderline not significant. These parameters formed the most reliable basis for predicting IVF outcome. After IVF, the percentage of live spermatozoa determined by using N‐E staining was the only sperm quality parameter showing a significant association with the PN formation ability of a given bull. This sperm quality test can be used as a non‐invasive method to estimate the PN formation ability of oocytes which are further cultured to assess embryonic development.     

种公牛阴囊周径与部分精液指标之间的相关性研究

通过对山东中大种公牛站现有四个品种(西门塔尔、利木赞、盖普威、荷斯坦)种公牛阴囊周径(scrotal circumference,SC)的测量,分析其与采精量、精子活率、精子密度、6周总采精量、6周总有效精子数5个指标间相关关系.结果表明:不同品种的种公牛SC之间差异显著(P＜0.01);同品种不同年龄的种公牛SC之间差异极显著(P＜0.01);不同品种间种公牛SC与精子活力、精子密度、总有效精子数呈正相关.     

夏南牛与夏洛来公牛精液品质的对比分析研究

[目的]通过比较夏南牛和法系夏洛来的精液品质,探索中原地区肉牛改良的适合品种。[方法]选择中原地区的夏南牛和法系夏洛来种公牛各5头,比较两个品种种公牛的精液品质（采精量、原精密度、原精活力、细管产量、冻后活力、精子畸形率）。[结果]表明：夏南牛公牛精液品质极显著的高于夏洛来牛。[结论]夏南牛公牛更适应中原地区的气候条件...     

荷斯坦牛和西门塔尔牛冻精品质及其体外受精后早期胚胎发育的比较研究

为探讨荷斯坦牛和西门塔尔牛冻精的精液品质及体外受精后胚胎发育能力的差异,利用目测法、低渗膨胀法和考马斯亮蓝染色法评估了荷斯坦牛和西门塔尔牛冻精的活力、质膜完整率和顶体完整率,并比较了二者冻精体外受精后胚胎的卵裂率和囊胚率。结果表明,荷斯坦牛和西门塔尔牛冻精的活力(30.4%和27.2%)、质膜完整率(41.96%和36.22%)和顶体完整率(77.02%和73.02%)均无显著差异(P>0.05),但荷斯坦牛冻精体外受精后的卵裂率(57.5%和48.6%)和囊胚率(30.3%和23.2%)显著高于西门塔尔牛冻精(P<0.05)。提示,不同品种公牛精液体外受精后的发育能力有显著差异(P>0.05)。     

鸡精液稀释配方对低温保存精子活力和输精效果的影响

为了完善中国南方地区鸡场公鸡精液的保存技术、提高精液的利用率，本试验研究了在低温（4 ℃）保存的条件下，不同的保存时间（0、4、8、24 h）、不同的稀释液配方（原精液、配方Ⅰ和配方Ⅱ）对精液的精子活力变化以及人工输精繁殖效果的影响。选用33周龄黄鸡母鸡192只、公鸡42只，192只母鸡依笼号分为12组（3种处理精液×4个保存时间），每组16只母鸡，公鸡不分组。统一采精后用两种不同稀释液稀释、低温（4 ℃）保存至0、4、8、24 h后观察精子活力，并对母鸡输精，分组收集鸡蛋，对各组受精率、出雏率、健雏率进行比较分析，以原精液低温保存作为对照。结果显示，两种稀释液组的精子低温（4 ℃）保存4、8、24 h，其精子活力极显著高于原精液组（P<0.01），配方Ⅱ组精子的活力高于配方Ⅰ组（P>0.05）；两种配方稀释液组的精液低温（4 ℃）保存4 h，输精受精率高于原精液组（P<0.05）；两种配方稀释液组的精液在低温（4 ℃）保存8 h，输精受精率极显著高于原精液组（P<0.01）。表明这两种精液稀释液更有利于精液保存，经稀释后的精液可以显著提高受精率，可为中国南方鸡场种公鸡精液保存技术的完善提供有力的数据支撑。     

A comparison of Friesian, Aberdeen Angus × Friesian and Belgian Blue × Friesian steers finished at pasture or indoors

Cross-breeding of dairy cows with beef bulls is common in Ireland with the Aberdeen Angus and Belgian Blue beef breeds both widely used. These breeds differ in maturity and consequently in their suitability for production systems differing in intensity and slaughter age. The objective of this study was to compare spring-born Holstein–Friesian (FR), Aberdeen Angus × Holstein–Friesian (AA) and Belgian Blue  × Holstein–Friesian (BB) steers slaughtered off pasture at the end of their second grazing season or slaughtered at the end of the second winter following indoor finishing. Fifty-four (18 per breed type) steers were managed together to 16 months of age. They were then blocked on weight within breed type and assigned to a 3 (breed types) × 2 (finishing strategies) factorial experiment. The two finishing strategies were (i) concentrate supplementation (mean 3.65 kg/day) at pasture for 105 days to slaughter, and (ii) pasture only for 105 days followed by indoor finishing on grass silage plus concentrates for 141 days to slaughter. Mean slaughter and carcass weights per day of age for FR, AA and BB were 852, 802 and 834 (S.E. 13.1) g, and 427, 412 and 452 (S.E. 7.3) g, respectively. Corresponding kill-out proportions, carcass conformation and carcass fat classes were 501, 514 and 542 (S.E. 2.4) g/kg, 1.90, 2.15 and 2.89 (S.E. 0.073), and 3.09, 3.27 and 2.59 (S.E. 0.122), respectively. The response to concentrates at pasture was 101 g live weight and 83 g carcass weight per kg dry matter. It is concluded that there were few differences between FR and AA in carcass growth and composition but BB had heavier carcasses of better conformation with higher proportions of lean meat and high-value lean joints than both FR and AA. Acceptable live weight and carcass weight gains were obtained on pasture plus concentrates but BB and FR carcasses were not acceptably finished off pasture. Both FR and AA produced acceptable carcasses following indoor finishing and BB carcasses, while below the target fat class, were acceptably finished based on internal fat and dissected carcass fat proportions.     

Colloidal Centrifugation of Stallion Semen: Changes in Sperm Motility,Velocity, and Chromatin Integrity during Storage

The current study investigated the changes in sperm quality (motility, velocity, and chromatin integrity) occurring during storage at room temperature or 5°C for up to 48 hours in spermatozoa after extension or single-layer centrifugation (SLC) through Androcoll-E. In unselected samples, all parameters of sperm quality deteriorated significantly during storage (P < .01), although the deterioration was faster at room temperature (22–30°C) than for cool storage (P < .01). The SLC-selected spermatozoa had higher motility, velocity, and chromatin integrity than the overall unselected population (motility: selected 85 ± 10%, unselected 56 ± 13%; P < .001; velocity: selected 85.1 ± 13 μm/second, unselected 63.5 ± 15 μm/second; P < .001; and DFI selected 12.2 ± 4.8 μm/second, unselected 23.6 ± 7.4 μm/second; P < .001). Furthermore, sperm quality did not deteriorate with storage in the SLC-selected samples, either at room temperature (22–30°C for 24 hours) or cooled to 4°C (for at least 48 hours), whereas a significant deterioration in sperm quality was observed in the unselected sperm samples (P < .01). Thus, room temperature storage of SLC-selected spermatozoa may be an option for insemination doses from stallions whose spermatozoa do not tolerate cooling. In addition, a new sperm analyzer, the Qualisperm, showed good correlation with subjective motility assessment (r = 0.8, P < .001), was user-friendly, and provided a reasonable volume of data. This instrument may be a useful adjunct to sperm quality assessment at the stud.     

内蒙古绒山羊精液冷冻过程中精子活力、活率及顶体变化的探讨

作者用Tris型稀释液冷冻山羊精液效果良好,解冻后精子平均活率达46.99%,最高活率为58%,顶体异常率在37%左右。