Training the novice stallion for artificial breeding.

Although the act of breeding is instinctive to the stallion, the use of a phantom mare and AV represent an unnatural element to this act. The use of these devices, as well as proper breeding manners and etiquette, must be taught to the stallion. The novice stallion usually learns these techniques rapidly and is quite manageable if proper restraint is used during training. Positive reinforcement for good behavior is essential. The ultimate goal in training the novice stallion is to develop an individual that will enter the breeding area with controlled enthusiasm, develop an erection and gracefully mount the phantom or mare in a quiet manner, and rapidly ejaculate into an AV.     

Training the novice stallion for natural breeding.

There are myriad problems that can arise when training the novice stallion for natural service. Many problems can be avoided by proper early training of the novice stallion. In the final analysis, common sense should prevail. The major ally of common sense is patience. One should keep in mind that the goal is to have a stallion behave in a disciplined manner, allowing for his expression of libido and effective mounting, intromission, and ejaculation. This is accomplished through judicious training and, as with any training process, takes some time and work. Proper training will help circumvent many potential problems and make the ultimate goal of impregnating mares more efficient.     

Evaluation of stallion semen.

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.     

Penile haemangiosarcoma in a breeding stallion

A 9‐year‐old Arab stallion was presented for haematuria and a haemorrhagic mass on the urethral process of the penis. Clinical examination and surgical excision suggested a tumour of the penis, histologically confirmed as a haemangiosarcoma. The stallion was successfully treated with surgical excision; however, successful breeding has not been achieved thus far (28 months). To the authors' knowledge, haemangiosarcoma of the equine penis has not previously been described.     

Atrial fibrillation management in a breeding stallion

A 20-year-old warmblood breeding stallion presented to a University practice for semen collection and evaluation was incidentally diagnosed with atrial fibrillation (AF). Electrocardiogram recordings during breeding revealed inappropriately rapid tachycardia and occasional ventricular premature depolarizations/aberrant ventricular conduction. Transvenous electrical cardioversion was performed. After successful cardioversion the horse displayed supraventricular ectopy and atrial contractile dysfunction and was administered sotalol hydrochloride in an attempt to decrease the risk of AF recurrence. Supraventricular ectopy and echocardiographic evidence of atrial dysfunction gradually improved and normalized over 6 months. No direct adverse effects of the chronic anti-arrhythmic treatment were observed and libido and semen quality were unaffected. AF recurred 6 months after cardioversion and sotalol therapy was continued to control the ventricular ectopy/aberrant ventricular conduction during semen collection. Considerations regarding pathologic arrhythmias and inappropriately high heart rates in breeding stallions with AF may be similar to those in riding horses. Sotalol hydrochloride was a safe anti-arrhythmic drug in the management of this case.     

Azoospermia due to testicular degeneration in a breeding stallion

In a breeding stallion with azoospermia clinical andrological evaluation, transscrotal testicular ultrasonography, testicular biopsy and hormonal analysis were carried out.For differentiation of testicular versus obstructive azoospermia a testicular biopsy was carried out. The histological examination revealed testicular degeneration.     

Factors associated with failure in breeding soundness examination of Western USA rams

Breeding-soundness examination (BSE) and eradication of Brucella ovis infection in rams are critical components of flock-health programs. The aims of this retrospective, cross-sectional study were to describe the results of BSE in a large sample of rams in the Western USA and to determine the association between BSE outcome and the semen collection method (penis manually extended vs. retained in the preputial cavity), ram body-condition score (BCS), the presence of ulcerative posthitis, and the size of the flock of origin. We evaluated the first BSE in a given year for rams from Colorado, Wyoming, and Utah, USA, from 2000 through 2007. Breeding-soundness examination consisted of physical examination, scrotal circumference and BCS measurement, semen collection by electroejaculation, and microscopic examination of semen motility, morphology, and leukocyte concentration. We assigned a reason for failure to each failed BSE and used multivariable logistic and Poisson regressions to measure associations between ram and flock variables and the risk or reason for failure on BSE. A non-random, owner-selected subset of rams was tested for antibodies to B. ovis by serum indirect ELISA (iELISA). The Rogan-Gladen corrected B. ovis seroprevalence was measured. Of the 14,667 BSEs performed on 11,804 rams, 29.0% were classified as "failed;" the most common reason for failure was substandard semen parameters (43.8%). Breeding-soundness examinations were more likely to have been categorized as failure for inflammatory causes when performed on rams from medium-sized flocks (OR 1.6; 95% CI 1.1, 2.3) and large flocks (OR 1.4; 95% CI 1.0, 1.9) (P=0.02), suggesting that larger flocks are at higher risk of contagious diseases. The adjusted seroprevalence of B. ovis antibodies among tested rams in this study was 10.0%. Of 233 rams seropositive to B. ovis, 125 (53.6%) were subclinical, a finding that supports the importance of this test in ram BSE. We found that emaciation in rams was associated with an increased risk of BSE failure from substandard semen parameters (P<0.001), but ulcerative posthitis and the semen collection method were not (P=0.09 and 0.34, respectively). However, collection of semen with the penis retained in the preputial cavity resulted in greater odds of leukospermia relative to semen collection with the penis extended (OR 4.1; 95% CI 2.9, 5.9; P<0.001), presumably from contamination of the semen sample with preputial leukocytes. For ram BSE, therefore, semen collection with the penis manually extended from the sheath is recommended to limit leukocyte contamination of the sample.     

Factors affecting breeding soundness classification of beef bulls examined at the Western College of Veterinary Medicine

Breeding soundness evaluation records from 2110 beef bulls, for the period of 1986 to 1999, were analyzed to determine the prevalence and importance of factors affecting breeding soundness classification. The percentage of all bulls classified as satisfactory ranged from 49.0% in January to 73.3% in May. The percentage of physically normal bulls with satisfactory semen quality ranged from 65.7% in January to 87.5% in June. Poor body condition or excessive body condition, below average or below the recommended minimum scrotal circumference, lameness, and severe scrotal frostbite significantly reduced the probability of a satisfactory breeding soundness classification. The percentage of sperm with midpiece defects declined significantly and the percentage of sperm with head defects increased significantly with the approach of summer. Photoperiod, cold stress, poor or excessive body condition, and reduced feed quality may interact to reduce semen quality in the winter months.     

Effect of scrotal bifurcation on breeding soundness traits in Beetal bucks during summer season

Relationship of scrotal bifurcation or splitness with breeding soundness traits was investigated in 15 Beetal bucks (17–20 months of age and 48.72?±?1.57 kg mean BW). Breeding soundness traits of conjoined/unsplit (n?=?6) scrotal bucks was compared with split (n?=?9) scrotal bucks having lengthwise >?1 in. bifurcation. Two consecutive semen ejaculations per buck were collected at monthly interval during summer season (April to June 2018) using intact buck as teaser and sexual behavior was simultaneously recorded. Scrotal morphometry parameters, i.e., scrotal circumference, scrotal volume, scrotal skin thickness, testis length, width, and thickness were also recorded. Bucks with split scrotum had relatively more scrotal dimensions (scrotal circumference (P?<?0.01), scrotal volume (P?<?0.01), testis length (P?<?0.01)) than conjoined scrotal bucks. Among various semen attributes, semen volume of first ejaculate (P?<?0.01), second ejaculate (P?<?0.05), mean semen volume (P?<?0.01), total sperm count of first ejaculate, and mean sperm count of both ejaculates were more (P?<?0.01) in split scrotal bucks. However, scrotal bifurcation had no influence on sexual behavior of bucks. It is concluded that Beetal bucks with split scrotum had relatively better breeding efficiency traits than conjoined scrotal bucks.

     

The effect of amount of body fat and loss of fat on breeding soundness classification of beef bulls.

Two hundred and fifty-one Aberdeen Angus, Horned Hereford, Polled Hereford, and Charolais bulls were examined at the time of sale (sale) and again from 10 to 85 days later (test) to determine the effect of amount of body fat and loss of fat on semen quality. Sale and test measurements included body weight, backfat depth, and scrotal circumference. Breeding soundness evaluations were done at test. For all bulls, over all years, the positive correlations of body weight loss vs. backfat loss, weight loss vs. scrotal circumference loss, and backfat loss vs. scrotal circumference loss were highly significant. Aberdeen Angus, Horned Hereford, Polled Hereford, and Charolais bulls lost weight at a mean rate of 1.77, 2.19, 1.94, 1.16 kg per day, respectively, in the interval from sale to test. Bulls classified as unsatisfactory lost significantly more weight than satisfactory bulls. However, bulls classified as unsatisfactory did not differ significantly from satisfactory bulls in the amount of backfat at sale and test and in the amount of backfat lost. No significant relationship could be demonstrated between increments of backfat and classifications of breeding soundness evaluations. Bulls with satisfactory semen quality had significantly larger scrotal circumference measurements than those with questionable or unsatisfactory classifications. Backfat data at bull sales may be helpful in selecting bulls with desirable growth characteristics, as well as reducing the risk of purchasing bulls with poor semen quality due to excessive body fat.     

Llama medicine. Conformation and soundness

Conformational problems tend to be common in llamas and alpacas. Without setting a standard, basic conformation can still be evaluated by comparing with equine conformation, especially in terms of straightness of limbs. Good conformation should evoke a sense of balance in the observer. Conformation faults predispose to unsoundness.     

Adrenal-testis interaction in the stallion.

The authors describe the short and long term effects of synthetic adrenocorticotrophin and of cortisol on peripheral plasma testosterone concentrations in 2 stallions. A single injection of either hormone temporarily raised plasma testosterone concentrations but repeated injection (twice daily for 5 days) depressed plasma testosterone concentrations. Cessation of treatment was followed by a rise in plasma testosterone to concentrations higher than those in the pretreatment period. These findings are briefly discussed.     

Estimation of genetic parameters among breeding soundness examination components and growth traits in yearling bulls

Data on breeding soundness examinations (BSE) and performance traits were obtained on 549 yearling beef bulls at the San Juan Basin Research Center, Hesperus, Co from 1976 to 1984. Genetic parameters estimated for components of BSE included percent motility (PMOT), percent primary abnormalities (PPRIM), percent secondary abnormalities (PSEC), percent normal sperm (PNOR), scrotal circumference (SC) and BSE score (BSESC). Performance traits included birth weight, weaning weight, yearling weight and average daily gain. The least squares model included birth year, age of dam and breed as fixed effects, sire/breed as a random variable, and age and percent inbreeding as covariates. Paternal half-sib estimates of heritability were PMOT, .08 +/- .07; PPRIM, .31 +/- .09; PSEC, .02 +/- .05; PNOR, .07 +/- .06; BSESC, .10 +/- .06 and SC, .40 +/- .09. Phenotypic correlations among BSE components and growth traits were generally favorable. Genetic correlations involving percent secondary abnormalities were highly variable with large standard errors. Seminal traits improved as age increased and became poorer as inbreeding increased.     

Impact of selection for residual feed intake on breeding soundness and reproductive performance of bulls on pasture-based multisire mating

There is concern in the beef industry that selecting bulls for feed efficiency based on residual feed intake (RFI) may have a negative impact on bull reproductive performance and fertility. Here we investigated the impact of selection of bulls for low RFI on breeding soundness evaluation (BSE), reproductive performance, and fertility of bulls under natural service in multisire mating groups on pasture. Of the 412 RFI-tested bulls available, 98 (23.8%) were culled for performance, type, temperament, or other reasons, and 88 (21.4%) were culled for failing BSE, for an overall cull rate of 45.1%. From among the 314 bulls subjected to BSE, 32 (10.2%), 20 (6.4%), and 36 (11.4%) were culled for poor feet and legs, scrotal circumference, and semen quality, respectively. The BSE traits were not different (P > 0.10) between bulls categorized as either inefficient (+RFI) or efficient (-RFI), but the proportion of bulls that failed to meet the 60% minimum sperm motility requirement tended (P = 0.07) to be greater in the -RFI group than in the +RFI group (10.2% vs. 4.4%, respectively). In a subpopulation of 115 bulls, individual progressive sperm motility was greater (P < 0.05) in +RFI (85%) than -RFI (80%) bulls. A multisire natural mating experiment was conducted during 2 consecutive breeding seasons (2006 to 2007 and 2007 to 2008) using 18 +RFI and 18 -RFI bulls. The overall calving rate (calves born/cows exposed) was 72.9%. Mean number of progeny per sire was significantly greater (P < 0.01) in -RFI bulls (18.3) than in +RFI bulls (11.8). Selection for feed efficiency based on RFI appears to have no detrimental impact on reproductive performance and fertility in beef bulls bred in multisire groups on pasture. However, the decreased sperm motility and the greater number of progeny per sire associated with -RFI status need further investigation.     

Evaluation of a portable device for assessment of motility in stallion semen

In horse breeding, quality assessment of semen before insemination is often requested. Non‐laboratory‐based techniques for objective analysis of sperm motility are thus of interest. The aim of this study was evaluating a portable device for semen analysis (Ongo sperm test) and its comparison with computer‐assisted semen analysis (CASA). Semen was collected from 10 stallions, diluted to 100, 50 and 25 × 10⁶ sperm/ml and analysed for total (TM) and progressive motility (PM). The final sperm concentration influenced total motility analysed by Ongo (p < 0.05) which was higher at 100 × 10⁶ sperm/ml when compared to 25 × 10⁶ sperm/ml (p < 0.05) but not when compared to 50 × 10⁶ sperm/ml (n.s.). Sperm concentration did not influence total motility when assessed by SpermVision (n.s.). Agreement between methods was evaluated by correlation analysis and Bland–Altman plot. Intra‐assay variation of Ongo was 5.2% ± 3.0 for TM and 6.9% ± 3.4 for PM. Correlation between Ongo and CASA was r = 0.79, 0.88 and 0.83 for 100, 50 and 25 × 10⁶ sperm/ml for TM, and r = 0.87, 0.89 and 0.87 for PM, respectively (all p < 0.001). At the 100 and 25 mio/ml dilutions, the difference between the two systems deviated significantly from 0, while no such bias existed at the 50 mio/ml dilution (TM Ongo 85.0%, CASA 82.3%; PM Ongo 64.1%, CASA 66.1%). The 95% confidence interval was 19.9%, 18.9% and 19.2% ± mean for TM and 20.7%, 17.4% and 20.3% ± mean for 100, 50 and 25 × 10⁶ sperm/ml, respectively. In conclusion, Ongo sperm test sperm motility data were strongly correlated with data obtained by CASA. In addition, at a concentration of 50 × 10⁶ sperm/ml values measured with both systems were close to identical. At this concentration, which is recommended in equine AI, Ongo and CASA can be used interchangeably.