Preparation of Teaser Bull for Effective Estrus Detection in Cattle

Preparation of a teaser bull refers to the process of modifying a healthy and fertile bull into an infertile one that can be used to detect estrus (heat) in females without the risk of causing pregnancy. This is achieved by rendering the bull sterile or preventing penile penetration, while retaining its libido and mating behavior.

Accurate detection of estrus is a key to a successful artificial insemination (AI) program in animals. Estrus detection is an important tool to evaluate the efficacy of the synchronization protocols and to troubleshoot problems.

Several estrus detection methods exist, including tailhead paint; mount detectors, self- adhesive heat detection patches, and visual observation.

All these methods depend on female cattle standing for mounting during estrus. Thus these methods might miss females with weak or short estrus behaviour.

Bulls are the most efficient estrus detector and hence utilization of a teaser bull (intact sterilized male) is the most reliable method of estrus detection in the utilization of an AI program.

Consideration for Teaser Bull Preparation

• First and most important is to be sure that the bull is unable to impregnate the cows
• Secondary importance in creating a teaser that is a non-entry teaser and will not spread venereal disease.
• A third aspect is the libido of the bull.
• Young bull is far more sexually active than an older more lethargic bull, and therefore makes a superior teaser bull.
• Teaser bull should be prepared every year because teaser bull will remain sexually active for a year.
• The ideal bull needs to be of moderate size, mild temperament, and easily handled.

Methods of Preparation of Teaser Bull

Teaser bull procedures can be divided into two categories: those that block semen flow and deliver sterility and those that prevent penile penetration.

There are several methods for preparation of teaser bull:

1. Vasectomy
2. Epididymectomy
3. Penile-prepuce translocation
4. Penopexy
5. Preputial pouch technique (Preputial obliteration)
6. Artificial corpus cavernosal thrombosis
7. Phallectomy (Penectomy)
8. Transection of the apical ligament

1. Vasectomy

Vasectomy is one of the earliest techniques described for the preparation of a teaser bull. Vasectomy will render a bull sterile but does not prevent normal mating and copulation behaviour.

2. Epididymectomy

The epididymectomy consists of removing the tail of epididymus, and this technique has been described for both bulls and rams.

Caudal epididymectomy is preferred over vasectomy because the caudal epididymectomy is easier to perform.

3. Penile-prepuce Translocation

Penile-prepuce translocation (“sidewinder”) is the surgical transposition of the penis and prepuce from the ventral midline to the right or left flank of a bull.

This procedure allows normal protrusion and erection but does not permit intromission.

4. Penopexy

Penopexy is the iatrogenic creation of phimosis by surgically creating an adhesion of the penis to the ventral body wall.

This procedure prevents protrusion of the penis, thus preventing normal intromission or copulation.

5. Preputial Pouch Technique (Ventral Slot with Preputial Orifice Obliteration)

The preputial pouch technique creates a fistula on the ventral prepuce and closes the normal preputial orifice. This technique prevents penile extension but allows for passage of urine through the ventral fistula.

6. Artificial Corpus Cavernosal Thrombosis

Artificial corpus cavernosal thrombosis is a surgical method used to render a bull incapable of penile erection. In this procedure, thrombogenic agents are injected into the corpus cavernosum of the penis to induce localized clot formation, leading to fibrosis and permanent loss of erectile function.

7. Phallectomy (Penectomy)

Phallectomy, also known as penectomy, involves the complete surgical removal of the penis. This irreversible procedure is usually reserved for situations where preventing intromission and semen deposition is critical.

8. Transection of the Apical Ligament

Transection of the apical ligament is a technique aimed at preventing penile extension and intromission during mounting. The apical ligament, which supports the distal end of the penis, is surgically cut to disrupt the alignment and rigidity needed for penetration.