SIR, – I read with interest Jim Cameron’s letter in The SF (December 19 issue) debating methods of semen testing bulls.

Jim is correct in stating that artificial vagina (AV) collection of semen is still the method of choice in bull studs worldwide for collection of semen for processing and freezing. However, as somebody that has been involved in training many vets in the technique of electro-ejaculation (EEJ) since its introduction into UK over 15 yrs ago, I thought it was worth clearing up any potential confusion around the role of the two techniques.

AV collection is the gold standard method of collecting semen from a bull as it allows an assessment of physical ability to serve as well as providing a sample of semen for examination and /or processing for AI. The primary role of EEJ is that it allows routine pre-breeding examination of large numbers of stock bulls to be carried out safely and efficiently on farm.

After a thorough physical examination in a suitable handling crush, EEJ provides a 'biopsy' of semen to allow detailed sperm motility and morphological examination which can often reveal problems that physical examination alone would not have detected.

I agree with Jim that a healthy bull with normal physical examination and scrotal circumference (SC) findings should not be condemned on the basis of failure to produce an ejaculate with EEJ. These bulls can be re-examined by EEJ on a later date or collected by AV if indicated.

All stock bulls should have an annual pre-breeding physical examination, with detailed palpation of the scrotal contents and SC measurement and semen quality evaluation by EEJ adds another level of confidence to their suitability for breeding.

Physical ability to serve needs proven with an oestrus female and should be monitored during the breeding season. Without the technique of EEJ, the routine pre-breeding examination of stock bull studs would simply not be done and we would miss the opportunity to detect many potentially sub-fertile or infertile bulls that can cause enormous economic loss.

Colin Penny MRCVS

60 St Albans Road,