Manual stimulation of bull on semen collection.
|Friction cannot make bull ejaculate|
Press bull penis glans tight after erection will make him ejaculate quite soon, see the video below.
Good demo video of manual stimulation on bull.
Bull (Bos taurus indicus) ejaculation induced by manual stimulation of the penis.
In the case of electroejaculation, this collection method does not allow the evaluation of the male's libido (Barth et al., 2004). The semen collected by this method presents greater volume when compared to the artificial vagina, however the total number of spermatozoa does not differ between the ejaculates obtained in both techniques (Austin et al., 1961). Furthermore, electroejaculation is prohibited in some countries, requiring an alternative semen collection technique for field bulls (Persson et al., 2007).
Rectal massage of the ampullae of the vas deferens is one of the simplest methods of semen collection in cattle (Palmer et al., 2005). However, ejaculates collected in this way have low quality, low sperm concentration and high contamination (Ohashi, 2008). Palmer et al. (2005) demonstrated that bull semen samples collected by massaging the ampoules had a lower percentage of motility and live spermatozoa when compared to semen samples obtained by electroejaculation. Semen collection by manual stimulation of the penis is the method of choice for dogs (Kutzler, 2005) and swine (Hancock and Howell, 1959). And this technique has already been described in other animals such as the stallion (Crump and Crump, 1989; McDonell and Love, 1990), the zebra (Crump and Crump, 1994) and the bat (Melville et al., 2008) but there are no reports in cattle, until now. The objective of this work is to describe the collection of semen in cattle by manual stimulation of the penis.
MATERIAL AND METHOD
To carry out this study, a 96-month-old purebred Nelore bull (Bos taurus indicus) was used, kept in the field and used for natural breeding. The animal was not conditioned for any semen collection technique. For the development of the work, the bull was transported and housed in an individual pen at the Veterinary Hospital of the Federal University of Paraná, where it received a diet based on corn silage and ryegrass hay, in addition to water and mineral salt ad libitum. In the first phase of the experiment, the bull was submitted to a conditioning process that consisted of performing perineal massage and manual stimulation of the penis twice a week at regular intervals, for three consecutive months. These procedures always took place at the same time in the morning, in the same environment, and were performed by the same person. At the end of each session, the bull received a reward (food) and then released into a paddock. The breeder had a docile temperament, minimizing risks for the technician.
Prior to semen collection, the foreskin was cleaned with a warm shower (36°C) and dried with a paper towel.
Collection by the manual stimulation method was not performed in the presence of a cow in estrus and did not require animal restraint.
The technique consisted of massaging the perineal region (Figure 1A), with movements from top to bottom, until the animal had an erection with exposure of the free end of the penis at the preputial ostium.
After the erection, pressure was exerted with the fingers on the glans (Figure 1B) until the animal responded with friction movements. At the moment of propulsion, the body of the penis was held and pressed with a gloved hand, to mimic the vagina of the cow, and the collection cup was positioned at the free end of the penis to collect the ejaculate (Figure 1C).
The collection cup consisted of a glass funnel attached to a sterilized test tube heated to 36°C.
|Figure 1 - Semen collection technique by manual stimulation of the penis in the bull|
A: massage in the perineal region;
B: digital pressure on the glans;
C: collection of the ejaculate at the moment of propulsion.
After conditioning the animal, collections were performed twice a week with intervals of three days, for three consecutive weeks to evaluate the ejaculates and to time the duration of the collection, from excitation to ejaculation. These samples were placed in a water bath at 36°C and evaluated for macro and microscopic characteristics: aspect, volume (mL), progressive motility (%), spermatic vigor (1 to 5), turbulence (1 to 5), concentration sperm count (per mL), total number of spermatozoa (per ejaculate) and sperm morphology. Motility, vigor and turbidity evaluations were subjectively performed in an optical microscope at 200x magnification, and sperm concentration determined by sperm count in a Neubauer chamber at 400x magnification. The examination of sperm morphology was performed using a smear stained by the Cerovsky method (CBRA, 2013), with a differential count of 200 spermatozoa using a magnification of 1000x in immersion oil. The pH of the semen samples was determined with a pH meter.
Three months after the start of conditioning, semen collection by manual stimulation was successfully performed. After this step, collections continued to be carried out twice a week, sometimes by different people. There were sessions in which erection and ejaculation occurred and others in which collection was unproductive. After another month of this work, the semen collection was productive in 90% of the attempts, even when performed by different people. The results of the ejaculate evaluations and the duration of collection using the manual penile stimulation technique are described in Table 1. All samples had a creamy white appearance. The mean volume was 6.5 ± 1.17 mL; mean progressive motility 83 ± 4.47%; stamina 5; vortex 5; pH 6.05 ± 0.09; sperm concentration 1.475x109 ± 0.32x109 per ml; total number of spermatozoa 9.87x109 ± 3.64x109 per ejaculate and mean percentage of abnormal spermatozoa of 9.6 ± 2.07%. The mean duration of collection was 176.2 ± 12.93 sec.
The semen collection technique by manual stimulation has advantages over the artificial vagina and electroejaculation. Among them, the ease of execution after conditioning the animal, elimination of the need for a female in estrus and/or dummy and animal restraint (less stress), lower operational and instrumental cost, less time spent during the procedure and need for fewer people to carry out the procedure, relevant advantages for reproduction centers. In addition, it could be used for breeders with locomotor or neurological problems who have difficulty or inability to mount. Among the difficulties for performing the technique are the bull's temperament and the relatively long time for conditioning. Similarly, for semen collection with the artificial vagina, males also need conditioning (Palmer, 2005). Another limitation of the manual stimulation method is the fact that it is not possible to evaluate the animal's sexual behavior during copulation, an important parameter during the libido test. For this reason, the technique is recommended for the collection of semen from bulls in semen collection centers, and not for andrological evaluation.
Much has been done with regard to animal welfare. There are alternative techniques for electroejaculation, since this semen collection technique causes discomfort to the breeders (Filho et al., 2009). Among them, the conventional artificial vagina, transrectal massage of the ampoules, use of medication (Palmer, 2005) and the internal artificial vagina (Barth et al., 2004) stand out. In cattle, the technique of manual stimulation of the penis may represent another alternative for semen collection, generating minimal or no stress to the bull.
Currently, genetic improvement programs include temperament among their selection parameters. The aim is to select animals with docile behavior, since they represent lower risk factors for those who handle them and better productive performance (Voisinet, 1997). In a study carried out by Figueiredo et al. (2005), with 5754 Nellore animals, approximately 50% were classified as slightly reactive, 29% as docile and 4% as very docile. It should be taken into account that the bulls to be conditioned for performing the semen collection by manual stimulation of the penis are selected according to their temperament, recommending docility.
Several researchers have demonstrated the influence of the semen collection method on the characteristics of the ejaculate. Leon et al. (1991) analyzed 51 ejaculates collected by artificial vagina from 20 bulls and found the following results: mean volume 5.8 mL, mean progressive motility 80%, pH 6.96 and sperm concentration 1.051x109 per mL. Analyzing these data comparatively, we observed in the present study higher mean values of sperm volume and concentration compared to the artificial vagina, as they result in a greater total number of spermatozoa per ejaculate, and consequently more insemination doses, since the progressive motility was similar. The low pH values of the semen collected by the proposed technique may be related to the acidic diet based on corn silage, since Leon et al. (1991) did not specify the feed provided to the animals. The evaluation of sperm morphology was within the range considered normal for the species (CBRA, 2013). Persson et al. (2006) analyzed 47 ejaculates from 52 bulls obtained by transrectal massage of the ampoules, which presented a mean volume of 3.2 mL, mean progressive motility of 43.5% and mean sperm concentration of 201.9x106 per mL. Comparing again with the results of the present work, the sperm parameters obtained through the collection of semen by manual stimulation of the penis were superior to those previously reported.
Manual stimulation of the penis represents a promising method for collecting semen in bulls, and further studies are needed to prove its repeatability.
|Bull reproductive system.|