LORI.bovine

Technique for artificial insemination; bovine.

Keywords:  bovine, vagina, insemination, A.I., AI, technique.

Routine artificial insemination (AI) in cattle is more complex than routine AI in mares.  The common method of AI in mares usually involves non-frozen semen. A gloved hand is simply inserted into the vagina then a finger into the cervix, enabling guidance of an insemination pipette into the uterus. In cattle, semen is almost invariably frozen and must be thawed carefully then inseminated by guiding an insemination rod through the cervix using transrectal manipulation. The bovine vagina, especially in heifers, will not permit the easy entry of a gloved hand and certainly, a finger cannot be passed through the cervix of a normal non-pregnant cow or heifer.

Excellent basic guidelines on those procedures can be found in publications such as this one from the UAE. or this, from Penn State University.

The intent of this entry is to illustrate the mechanics of handling an insemination rod and the act of insemination itself. The author is indebted to Select Sires US & Canada for allowing these images to be used in LORI. Select Sires holds the copyright to all images in the entry and should be contacted regarding their use outside of this image library.

After removing most of the feces from the rectum, the gloved hand is used to grasp the cervix transrectally. Then, using paper towel, the vulva lips are cleaned briefly, and the cow's tail is deflected to one side using the arm in her rectum. The vulva lips are parted (if a helper is not available, one of  the techniques described in the text box below can be used) and the AI gun is inserted into the vestibule at an upward angle. Obviously, care must be taken not to contaminate the vagina. See figure 1. It is important to grasp the cervix and push it cranially to eliminate vaginal folds that often impede passage of the AI gun.

Figure 1. An AI gun is inserted to the level of the external cervical os. In the author's opinion, the hand shown here should advance cranially to hold the entire cervical body. Holding the entire cervix in one's hand allows it to be manipulated effectively. At this point, the author also advances the AI gun so that it can be felt against the fifth digit (small finger) in the ventral part of the cervical fornix. With the entire cervix is within one's grasp, the external cervical os is lifted and fed over the tip of the AI gun. Image size:1000 x 680

Variations: One can hold the base of the loaded insemination between one's teeth; a valuable "third hand". The paper towel that has been wrapped around the AI gun to prevent semen cold shock, is removed. Some technicians fold this paper towel, kink it and place it in the ventral vulva commisure. This opens the vulva lips and serves as a surface upon which to slide the AI gun upward and into the vagina. In any case, the vulva lips should be wiped as clean as possible; generally not repeating this action without more paper towel, as that leads to more contamination than otherwise. The author uses a different approach, pushing down slightly on the cleaned perineal body using the elbow of the arm in the rectum. This causes the vulva lips to gape while the AI gun is inserted into the vagina.

  

Figure 2. An approach where the cranial vagina is narrowed over the external cervical os to facilitate entry of the AI gun into the external cervical os. As stated above, the author uses a different to technique to locate an entry point for the AI gun. The external cervical os can also be located using an endoscope designed for this purpose. However, this does not necessarily facilitate passage of the AI gun through the cervix, often the most challenging part of AI in cattle. Image size:1000 x 680

Using either technique, after the AI gun has entered the cervical canal, the rings of the cervix are manipulated over the tip of the AI gun.  See figure 3. Note the emphasis on manipulating the cervix over the gun and not placing primary emphasis on moving the gun cranially, attempting to bypass the cervical "rings" (they are not true rings but a series of crescents). The AI gun should not be forced cranially in hopes of displacing the annular rings .

Figure 3: Manipulating the annular rings (folds) of the cervix over the AI gun as it is moved gently towards the uterine body. Image size: 800 x 554

Although it is not illustrated in this entry, it is essential to place a finger over the cranial aspect of the cervix to determine that the AI gun has emerged from the internal cervical os and lies within the uterine body. The plunger of the AI gun is then depressed, expelling semen into the uterus (see figure 4). One should ensure that the AI gun is not pulled caudally into the cervix while the plunger is depressed.

Figure 4. Depositing semen within the uterine body. Image size:1000 x 680

Clitoral stimulation in both cows and heifers immediately after insemination has been shown to increase pregnancy rates marginally in some studies but this effect (especially in heifers) is not consistent. 

Some studies show advantages to intra-cornual (in the uterine horns) insemination, others not. The situation remains unclear. For routine AI therefore, it is reasonable to suggest that semen should be deposited within the uterine body (the short section of the uterus that extends only 2 to 3 cm cranial to  the internal cervical os). On the other hand, there appear to be no detrimental effects when intra-cornual insemination is used. Therefore intra-cornual should be considered when sexed semen is used or when super-ovulation is practiced.  Passing an AI gun up the uterine horn requires different techniques to those shown here, akin to those used for embryo collection. 

Selected references:

Carvalho P.D. et al. 2013 Effects of deep-horn AI on fertilization and embryo production in superovulated cows and heifers. Theriogenology. 80:1074–1081

Ciro, M. et al . Comparison between deep intracornual artificial insemination (dIAI) and conventional artificial insemination (AI) using low concentration of spermatozoa in beef cattle. Braz. arch. biol. technol.[Internet]. 2012 June.cited 2019. 55: 371-374.

Lunstra, D.D. et al. 1983. Clitoral stimulation and the effect of age, breed, technician, and postpartum interval on pregnancy rate to artificial insemination in beef cattle. Theriogenology. 19:555-563

Momont, H. et al. 1989 Does intrauterine site of insemination in cattle really matter? Theriogenology 32:19-26

Segura, C.V.M. and Rodriguez, R.O.L. 1994. Effect of clitoral stimulation after artificial insemination on conception in Zebu-crossbred heifers in the tropics. Theriogenology 42:781-787