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1.
The time required to train rams to an artificial vagina (AV) makes collecting semen from large numbers of rams difficult. To manage this problem, we developed a glass, round-bottomed, 1.9-cm i.d. x 9.8-cm long vaginal collection vial (VCV). Three experiments were conducted to determine whether the VCV affected 1) semen volume per collection, 2) percentage of motile spermatozoa, 3) forward progressive motility score before and after extension and after freezing and thawing, and 4) our ability to collect semen from untrained rams. A soft rubber cap with a hole in the center was used to cover the VCV. A VCV was inserted into the vagina of an estrual ewe, and a monofilament line attached to the VCV was clipped to the wool near the vulva. Rams were joined with unrestrained ewes in a pen until they ejaculated into the VCV. In Exp. 1, five rams trained to an AV were used in a switchback design with four collection periods. During each period (1 d), semen was collected with an AV and a VCV. Immediately after collection, semen volume and sperm motility were quantified. Semen was extended with an aloe vera gel-based diluent at a 1:4 dilution rate, motility was quantified again, and semen was frozen. At 1 h after freezing, semen was thawed and sperm motility was quantified. Ejaculate volume (mean = 0.7 mL) and all measures of motility after collection were similar (P > 0.05) for the two collection methods. In Exp. 2, 10 rams trained to an AV were used in a switchback design with five collection periods (period = 3 d). On d 1 and 3 of each period, an AV and a VCV were used to collect semen. Collection method did not affect (P > 0.05) ejaculate volume (mean = 1.0 mL), percentage of motile cells, or forward progressive motility score. In Exp. 3, 51 untrained rams were used in a switchback design with a single collection period (2 d). Semen was collected with an AV and a VCV. Ability to collect an ejaculate and time required for collection were recorded. The likelihood of collecting semen from untrained rams was greater (P < 0.01) using a VCV (mean = 31.4%) than using an AV (mean = 9.8%). Collection method did not affect (P > 0.05) ejaculate volume (mean = 0.8 mL), percentage of motile cells, or forward progressive motility score. We concluded that a VCV could be used to collect semen from rams that are not trained for semen collection without decreasing ejaculate volume or sperm motility.  相似文献   

2.
Artificial vagina (AV) and electroejaculation (EE) are the 2 methods used to obtain semen from bulls. The purpose in the present study was to evaluate these 2 methods of collection when 2 markers, cortisol and progesterone, were injected IV. During period 1 (control measurement), semen was obtained by EE at 0, 20, 60, 120, and 180 minutes. In period 2, bulls were injected (3 days later) with a mixture of cortisol (113 mg) and progesterone (100 mg), and then samples were obtained by EE. In period 3, cortisol and progesterone were injected (3 weeks later), and samples were obtained by AV. Seminal plasma concentrations of cortisol and progesterone were maximal at 20 minutes in EE and AV collections. Seminal plasma concentrations of progesterone and cortisol were roughly 50% less in EE than in AV collection. However, the total excretion of progesterone and cortisol per collection was similar in both techniques. Excretion of cortisol was 14 to 33 times greater than that of progesterone. It was concluded that concentrations of markers in the EE were significantly less than those in AV collection. For this reason, total excretion and concentration of marker in semen should be accounted for when conducting excretion studies.  相似文献   

3.
This study was conducted to evaluate changes in ram seminal plasma composition from ejaculates obtained using artificial vagina (AV) and electroejaculation (EE). To address this question, we assessed the effect of semen collection method on volume, sperm concentration, sodium concentration, potassium concentration, sodium/potassium ratio, total protein content and protein profile using sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) and 2-D polyacrylamide gel electrophoresis. The main findings from this study were: (i) similar volume was obtained, while sperm concentration was significantly lower for EE method; (ii) potassium and sodium/potassium concentration ratio were not influenced by recovery method, while sodium concentration increased significantly when semen was recovered using EE; (iii) approximately 80% of the total relative seminal plasma protein is represented by four protein fractions of molecular weights around 15, 21, 24 and 50 kDa and there were not differences and (iv) focussing the two-dimensional SDS-PAGE gel on the 10–25 kDa rank, the image analysis software detected around 22 spots with isoelectric points ranging from 5.1 to 6.1. Two protein spots (15 kDa and 5.5 and 22 kDa and 5.2 for molecular weight and isoelectric point respectively) increased significantly when semen was recovered using EE. One spot protein with molecular weight around 25 kDa and isoelectric point of 5.2 were only found in the seminal plasma from the semen recovery by AV. As it was demonstrated, ejaculates obtained with EE modify the sodium concentration, alter two proteins concentration and induced the loss of one protein in seminal plasma.  相似文献   

4.
This study was conducted to evaluate the response of Bali bulls (Bos javanicus) to different semen collection methods and their effects on fresh and post‐thawed semen quality. The collection methods employed were electro‐ejaculation (EE), transrectal massage (RM) and RM followed by EE (RM + EE). A total of 25 untrained Bali bulls (age between 2 and 4 years old) were subjected to the different semen collection methods. Fresh semen samples from all the 25 bulls were evaluated for volume, pH, general motility, live/dead ratio and abnormality using the conventional method. For fresh and frozen samples collected by EE and RM from 10 bulls, computer‐assisted semen analysis system was used for precise quantitative measurement of motility, velocity and forward progression. Accucell photometer was used to measure sperm concentration in all samples, regardless fresh and frozen. Semen samples were obtained 100% of the attempts using EE, 84% using RM and 96% using RM + EE. There were no differences among the collection methods for fresh semen quality characteristics, including motility, morphology and viability, but pH and volume were higher for EE than RM and RM + EE. Higher sperm concentration was observed in semen collected by RM than the other two methods. Different age groups (2–3 and >3–4 years old) of the bulls did not show significant differences in volume, pH, sperm concentration, percentages in motility, live/dead ratio and normal sperm morphology. The quality of semen for general and progressive motility, VAP, VSL and VCL and acrosomal integrity after thawing was higher for RM than EE. In conclusion, Bali bulls appeared to respond best to EE and the combination of RM + EE than RM, as a method of semen collection, with a shorter time of stimulation required. Differences in age of the Bali bulls did not affect the semen quality.  相似文献   

5.
This study aimed to develop a polymerase chain reaction (PCR)‐based sexing and effective semen collection methods for black‐headed and straw‐necked ibis species. However, most birds are not sexually dimorphic, that is, the sexes appear similar. Therefore, the gender should be determined before semen collection. DNA was extracted from the blood samples of 11 black‐headed and 4 straw‐necked ibis. The sex was determined after PCR amplification of the EE0.6 region of W‐chromosome. The PCR products were separated using gel electrophoresis. A single band indicated the presence of the EE0.6 region and that the individual was a female, while no band indicated that the individual was a male. Further, the single bands from seven specimens were amplified. Semen collection was performed by massage or a combination of massage with electro‐ejaculation and was attempted during all four seasons. The semen was successfully collected in March from male straw‐necked ibis using the massage method. Limited motility, viability and concentration of straw‐necked ibis sperm were observed. The sperm length was 180 μm and that of the nucleus was 30 μm with acrosome located at the tip of the nucleus. Thus, the PCR‐based sexing proved to be an accurate molecular sexing method for black‐headed and straw‐necked ibis. Furthermore, we successfully collected semen and observed the stained sperm nucleus and acrosome of the straw‐necked ibis sperm. We propose that the use of this PCR methodology can be applied as a routine method for sex determination and semen collection in ibis species for future ecological research. However, considering our limited success, further studies on semen collection method are required.  相似文献   

6.
This article outlines a basic method for conducting a stallion semen evaluation. After the removal of the gel fraction of the ejaculate, semen gel-free volume is determined, and any abnormality in appearance is noted. Concentration of sperm cells in semen can be determined with the use of either a hemacytometer or spectrophotometer after appropriate dilution of raw semen. The percentage of progressively motile sperm is evaluated promptly after collection of semen with the use of a phase-contrast microscope. The total numbers of sperm and progressively motile sperm in the ejaculate are calculated. The determination of seminal pH and the classification of sperm morphologic features are additional seminal characteristics evaluated during a semen evaluation. Sperm motion characteristics can be further evaluated with the use of computerized sperm image analysis systems and may add additional information concerning the quality of ejaculated sperm. Unfortunately, no single seminal characteristic has in itself been shown to be highly correlated with fertility, although various seminal characteristics are known to affect fertility. Therefore, to properly interpret the fertility of a semen sample, a complete and thorough semen evaluation must be performed.  相似文献   

7.
Low egg fertility and hatchability is a common problem in captive populations of rockhopper penguins (Eudyptes chrysocome chrysocome). These conditions make sustaining a captive population challenging. A method for collecting and evaluating semen from rockhopper penguins was developed to assist in the evaluation of low egg fertility found in one captive population. Six adult male rockhopper penguins were conditioned to allow semen collection once a week from the start of breeding season until ejaculates no longer contained sperm. A total of 59 ejaculates was collected between 17 September and 31 December 2004. Forty-five of these samples were evaluated for volume, pH, sperm concentration, and sperm quality (motility, viability, and morphology). There was a large variation between individuals and between collections for each individual. The mean motility was 34.5% (+/- 22%). Mean volume of ejaculate was 0.23 ml (+/- .31 ml). Mean concentration was 16.9 x 10(6) sperm/ml (+/- 48.7 x 10(6) sperm/ml). Mean number of sperm per collection was 1.7 x 10(6) (+/- 4.2 x 10(6)). Mean percentage of living sperm was 82.9% (+/- 18.1%). Mean percentage of sperm with normal morphology was 82.1% (+/- 18.8%). Mean pH was 6.47 (+/- 0.49). During this season, only one of these males paired with a female. The pair produced one fertile egg, but the embryo died early in incubation. Male rockhopper penguins had low sperm concentration and low motility indicating that low male fertility may be contributing to the poor egg fertility rate. This work represents the first step in an ongoing study to improve captive breeding of rockhopper penguins.  相似文献   

8.
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.  相似文献   

9.
The present study investigated daily sperm output and sperm morphology of fresh semen in eight Swedish Warmblood stallions aged 5–8 years. They were used for artificial insemination, and their fertility during the breeding season of semen collection exceeded 60% per cycle. One ejaculate of semen was collected daily for 10 consecutive days from each stallion. The gel-free volume was measured, and the sperm concentration was assessed with a Bürker chamber. The volume of gel-free fraction was multiplied by the sperm concentration to give the total number of spermatozoa (TSN). Sperm morphology was examined in ejaculates collected on days 2, 5 and 10. An aliquot from each ejaculate was fixed in 1 ml formol–saline immediately after collection and examined under a phase-contrast microscope (magnification 1000×) to assess morphological abnormalities. Furthermore smears were prepared and stained according to Williams (carbolfuchsin–eosin) for a more detailed examination of the sperm heads under a light microscope (magnification 1000×). Analysis of variance was applied to data. Total spermatozoa number decreased progressively during the first 8 days of collection, and daily sperm output (DSO) was calculated as mean TSN of collections on days 8–10, being 6.4 × 109 spermatozoa. The overall percentages of morphologically normal spermatozoa in ejaculates collected on days 2, 5 and 10 were above 70%, being significantly lower in ejaculate 2 (68.6%) compared with ejaculates 5 and 10 (72.9% respectively 75.3%).  相似文献   

10.
采用后备北极公狐在配种期内用6个阶段的采精频率检测公狐精液的采出率、射精量、精子活力和密度。精液采出率以3月下旬和4月上旬最高,极显著地高于3月上旬(P<001);射精量以3月下旬和4月上旬最高,3月上、中旬最低(P<005);精子活力以4月上旬最高,极显著地高于4月下旬(P<001),但4月上旬与其他阶段差异不显著(P>005);精子密度以3月中旬和4月中旬最大,3月下旬最低,二者差异显著(P<005)。结果表明,不同的采精阶段对后备公狐的射精量、精子活力和密度均有一定的影响,尤其对后备公狐发情开始和接近结束阶段的影响更大。  相似文献   

11.
Males of Muscovy duck (Cairina moschata) are mainly used for mule duck production via artificial insemination of females originated from wild mallard duck (Anas platyrhynchos); therefore, the quantity and quality of drake semen play a crucial role. The assessment results of male reaction to sexual stimulation by dummy female and basic semen characteristic (ejaculate volume, sperm concentration and morphology) of 12 individually kept Muscovy drakes carried out during the entire reproductive season are described. The male and period of the reproductive season effect on scored semen traits are documented. In total, 792 individual semen collections and evaluations were performed. The average of positive reaction in the entire reproductive season varied from 90.6% in December and April to 50.0% in July, while for individual males, it varied between 97.1% and 29.0%. Throughout the season, the ejaculate volumes ranged from 0.05 to 2.45 ml, sperm concentration from 0.15 × 109 ml−1 to 4.44 × 109 ml−1, total number of live spermatozoa from 68.0% to 100% and live normal (properly formed, with any deformations) from 51.0% to 99.0%. Our study indicates the necessity of male breeders pre-selection before the onset of the reproductive season, and the need to leave an appropriate number of males to ensure adequate amount of semen for female insemination, especially when using Muscovy drakes (Cairina moschata) for interspecies crossing with Anas platyrhynchos ducks.  相似文献   

12.
Frequency of semen collection was used to determine methods of stabilising epididymal sperm reserves in young boars in order to measure daily sperm output which then allows estimation of daily sperm production. By collecting from boars 3 times a week (Monday, Wednesday and Friday) most boars reached epididymal stabilisation within 4 weeks and the daily sperm output could be calculated from the following 6 collections. A more rapid method of measuring daily sperm output was achieved by collecting from boars 4 or 5 times during one day and daily for the following 4 days. Daily sperm output measured by this method was not found to be significantly different from the method requiring collections over a 6-week period. Frequency of collection had a significant effect on semen characteristics. Collecting 3 times a week resulted in significantly greater volumes, sperm concentration, total number of sperm in the ejaculate and daily sperm output compared with collecting at intervals of 48 h. A collecting frequency of 48 h resulted in significantly greater volumes, sperm concentration and total number of sperm in the ejaculate but not daily sperm output when compared with collecting every 24 h.  相似文献   

13.
选择在广州地区亚热带气候条件下2岁~6岁的娟姗公牛5头,观察其精液品质(采精量、原精密度、原精活力以及细管精液产量)在全年不同月份的变化情况.结果表明:娟姗公牛的每次采精量和细管精液产量在气温较高的7~9月份会因为采精频率的减少而增加,10月份会因为周采精频率增加而使每次采精量和细管精液产量有明显减少;娟姗公牛的原精密度在气温适宜的2月份和采精频率较低的8月份会出现两个高峰值;娟姗公牛的原精活力在气温较高的月份会出现明显的下降趋势,2月份气温适宜时原精活力最好.  相似文献   

14.
The aim was to estimate the optimal frequency of semen collection from pigeons in relation to ejaculate volume, sperm concentration, total spermatozoa in ejaculate and percentage of live morphologically normal cells. The study was carried out on 455 ejaculates collected from two groups of pigeons, each of 10 males (group I: meat-type breed; group II: fancy pigeon). The birds were selected and kept individually in cages under a natural photoperiod. A two-person technique was used for semen collection (lumbo-sacral and cloacal region massage). Semen was collected once, twice or three times per week. Colour, consistency and volume of ejaculates were evaluated macroscopically immediately after collection. Sperm concentration and total number of cells in the ejaculate were estimated after dilution with Ringer's solution. A live-dead stain technique (nigrosin-eosin) was used to determine the percentage of live and normal spermatozoa. Semen collected 3x/week was of high quality. The average volume of a single ejaculate was small (21 microl in group I and 19 microl in group II), but sperm concentration was high--1.58 x 10(9)/ml and 1.96 x 10(9)/ml, respectively. The mean number of spermatozoa per ejaculate was 30.48 x 10(6) in group I and 39.49 x 10(6) in group II. An increased percentage of live and normal spermatozoa in semen collected more frequently was also observed. Collecting pigeon semen 3x/week provides spermatozoa in larger amounts and of better quality than less frequent collections (1x/week or 2x/week) and is recommended for obtaining more insemination doses.  相似文献   

15.
Since rabbit bucks are usually housed under constant long daylight in artificial insemination (AI) centers, the main purpose of this study was to investigate whether constant long day influenced ejaculate parameters of rabbits housed in AI centers in the Spanish Mediterranean area. The study was carried out in Murcia, Spain (37° N). Twenty commercial hybrid male rabbits, aged between 14 and 15 weeks, were randomly allotted to two groups and housed under either natural day length (n=10, ND) or a constant 16-h daylight exposure of 16 h (n=10, CLD). Other management conditions, such as air temperature or reproductive handling, were identical for both groups. Two successive ejaculates were collected twice weekly from every male, and the first one was used to monitor ejaculate characteristics. Measurement of semen production, in terms of ejaculate and semen volume, sperm concentration and total sperm per ejaculate, and sperm quality, in terms of motility index, viability, morphology and acrosome integrity, was assessed in 783 ejaculates collected during 15 months (from October to December). No differences (P>0.05) in either semen production or sperm quality were shown among ejaculates collected from rabbits housed under ND and CLD conditions. A limited influence of season was observed (P<0.01); semen volume and motility index were highest and lowest, respectively, during summer. The increase of air temperature and humidity index (THI) had a significant detrimental effect (P<0.01) on both sperm production and quality parameters with a lag of 6 and 3 weeks, respectively. On the basis of these findings, annual variations of semen production and sperm quality in male rabbits seems more related to THI than to daylight length under conditions of AI management in the Mediterranean area of Spain.  相似文献   

16.
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.  相似文献   

17.
The aim of our study was to compare the quality parameters of fresh feline ejaculates collected by three different techniques—urethral catheterization after medetomidine administration (CT), electroejaculation (EE) and epididymal slicing after orchiectomy (EP). A total of 34 adult male cats (Felis catus) were included in the study. In all male cats, the sperm collection was performed under general anaesthesia by three collection methods in the following order: urethral catheterization, electroejaculation and epididymal slicing. The sperm parameters evaluated were as follows: volume, motility, viability, sperm concentration, total sperm count and morphological examination. The highest quality semen parameters were achieved using EE. The comparison of results of the evaluated sperm quality parameters from EE and EP showed significant differences only in one case—the percentage of head abnormalities and lower percentage of head abnormalities were achieved using EE compared to EP: 8.5% (3.0%–21.0%) versus 10.0% (4.0%–22.0%). Semen collected by CT rendered the lowest quality samples when compared to sperm samples collected by EE and EP, especially with respect to the motility and total sperm count which were significantly lower (p < 0.001). Our study showed that sperm samples collected by EE and EP result in better quality of feline ejaculates compared to collection by CT from sperm samples collected from the same male cats. These results demonstrate the necessity of further research of urethral catheterization as a novel technique of semen collection in male cats.  相似文献   

18.

This study was conducted to determine the best combination between two collection method and two extenders in the cryopreservation of semen from creole bulls adapted to highlands of the Ecuadorian Andes. Sixty ejaculates from three adult Creole bulls were evaluated after collection by artificial vagina (AV) and electroejaculation (EE). Semen samples were split into two aliquots and diluted with a soy lecithin extender (Andromed®; A) or an egg yolk-containing extender (Triladyl®; T) and packed in straws of 0.25 ml with 20 × 106 sperms. Optical microscopy and computer-assisted semen analysis system (CASA) were used to evaluate semen quality characteristics. The effects of collection methods and extender type as well as its interaction were evaluated by a factorial ANOVA and Bonferroni’s test. Semen samples collected with EE and frozen with T (EE-T) and A (EE-A) had greater proportion of spermatozoa with optical assessed individual progressive motility (IPM), plasmatic membrane intact (HosT), and lower tail abnormalities than those obtained with AV and frozen with the same extenders (AV-T and AV-A); however, differences were significant only between EE-A and AV-T. CASA assessment indicated that the total mobility (TM) was greater (P < 0.05) in semen samples diluted with T, although these samples had a greater proportion (P < 0.05) of sperms with local motility (LM) and fewer immobile sperms (IS), than those extended with A. Generally, semen samples obtained with EE or AV and diluted with T seems to be the best option to ciopreserve gametes of Creole bulls raised in highlands of Ecuadorian Andes.

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19.
The level of fertility in the male ostrich exerts considerable influence on the efficiency of the fertilization procedure, and thus also on reproductive performance. The determination of the reproductive capacity is of particular interest with regard to the selection of single individuals for optimizing reproduction ratios. Although the breeding and raising of ostriches has become increasingly important in many countries, little research has been completed on reproductive parameters and factors that may possibly influence them. This study presents observations made concerning the quantity and quality of sperm as found in the spermatological testing of 411 ejaculate samples taken from male ostriches on two farms in Namibia. The semen volume varied between 0.1 and 1.5 ml (mean, 0.64 ml). Normal ejaculate colours ranged from white to ivory; the consistency ranged from thin creamy to viscous. The measured pH values lay between 6.4 and 8.0 (mean, 7.3). Microscopic investigations revealed sperm concentrations of 8.9–78.1 million/μl and individual sperm motility from 42 to 96% (mean, 78%). No mass motility was detectable in 42% of the ejaculates; weak mass motility was found in 46%, and clear mass movements were to be found in only 12% of samples. Regarding the morphology of the sperm, 5 to 26% were abnormal (mean, 17%) and 4 to 28% (mean, 20%) were dead. Seasonal patterns of sperm concentration and the influence of frequency of semen collection were investigated in a group of 56 healthy male ostriches. Peak sperm concentrations were found at the beginning of the breeding season in spring; the lowest values were found at the end of the breeding season in autumn. The highest quality ejaculate was obtained from those males whose semen was collected once a week. The results of this study provide fundamental data for the establishment of minimum quality requirements for ostrich sperm to be met by individuals receiving certification as breeding animals and for the selection of suitable males for use in artificial insemination.  相似文献   

20.
1. Seven 35-week-old Hubbard broiler breeder males were subjected to three semen collection frequencies either once every 2 d (48 h), daily (24 h) or twice daily (12 h). 2. Semen characteristics including motility, volume, concentration and sperm numbers per ejaculate were determined for each ejaculate. 3. Sperm motility was unaffected by collection interval, but semen volume was lower at 12 than 24h intervals. Sperm concentration was lower at 12 than 48h intervals. 4. At 24 and 48 h number of sperm per collection (1.7+/-0.2, 1.8+/-0.2 x 10(9)) were higher than at 12 h (1.2+/-0.1 x 10(9)). 5. The number of semen doses over a 6-d period increased linearly as the frequency of collection increased from once every 2 d to twice daily. 6. It is concluded that output was theoretically maximal at twice daily collection, but in practice not all cockerels may be able to maintain full performance with such a demanding regime.  相似文献   

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