Cervid Semen Collection and Freezing

CHAPTER 134 Cervid Semen Collection and Freezing




SEASONALITY


The cervid species mentioned in this section (wapiti, red deer, whitetailed deer, fallow deer, and sika deer) are all seasonal breeders. Because of the relationship between changing daylight length and fertility, there is a limited window of opportunity to collect viable semen1,2 (Fig. 134-1).



This window can be manipulated early via artificial lights or the use of melatonin implants. Melatonin implants have been successfully used to advance the breeding season of red deer.1 Starting 3 months before the normal breeding season, using one implant of Regulin (Regulin, Schering Agrochemical, Ltd., NSW, Australia) per month, it was possible to obtain good quality semen 1 month before other untreated bulls of the same age.2


However, there were undesirable side effects. These bulls rutted early when the temperatures were hot, and then changed into a summer coat in late winter when the temperatures were cold. They also showed irregular antler growth, going through two antler cycles in 1 year.2


At the beginning of the breeding season, a higher percentage of secondary abnormalities can be seen in the semen sample. The timing of this varies between individual males. Similarly, individual males will display a higher percentage of secondary abnormalities toward the end of the breeding season. In some instances an excess of 50% of sperm in one ejaculate will show distal droplets before cessation of viable sperm production.1



METHOD OF COLLECTION


Some workers have reported collections from dummy mounting, as well as indwelling condoms in ovariectomized females treated with estrogen, but realistically electroejaculation is the most accepted method. There are two methods of collecting semen by electroejaculation.



Under Anesthetic


Initially most cervid species were collected this way.1 However, from the late 1980s onward the method of choice to collect red deer and wapiti semen involved the use of no drugs, and a squeeze or chute.1


If wapiti or red deer are in full antler it may still be necessary to tranquilize or anesthetize them. Drugs used to induce lateral recumbency are listed in Table 134-1. They are either narcotic-based mixtures or a mixture of xylazine HCl and Telazol.1,3



Fentazine or the carfentanyl/xylazine mix is reversed with tolazoline hydrochloride (Tolazine, Lloyd Laboratories, Shenandoah, Iowa) (2–4 mg/kg, given half IM, half IV) or yohimbine hydrochloride (Antagonil, Vetrepharm, London, Ontario, Canada) (1.0–1.25 mg/kg) to reverse the xylazine, as well as Narcan (Naloxone hydrochloride injection, DuPont Pharmaceuticals, Dorval, Quebec City, Canada) to reverse the narcotic (Table 134-2). The more nervous smaller cervid species are best done under anesthesia. The drug combination of choice for whitetailed deer bucks is xylazine/Telazol mix. This is reversed with yohimbine or tolazoline hydrochloride (doses as previously given).



Cervids collected under anesthetic are in lateral recumbency with an assistant holding the back legs and another assistant holding the head.1


More electroejaculation stimulation is needed than in standing collection. Anesthetized males are more likely tospoil the collection with urine contamination or accessory sex gland contamination with this method.


A cleaner collection can be obtained by initially snaring the penis with a cotton bandage and directing it into a collection vessel, so as to avoid preputial contamination. Care is taken to collect the ejaculate in fractions, so that every collection can yield some viable sperm. If contamination from urine or accessory sex glands occurs, then that affected fraction is discarded.



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Sep 3, 2016 | Posted by in SUGERY, ORTHOPEDICS & ANESTHESIA | Comments Off on Cervid Semen Collection and Freezing

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