Bull Fertility testing

Bull Fertility testing
By Travis Scott, Veterinarian, Anexa Vets Raglan

For many of the dairy farms we deal with, bull performance after the AI period can be a significant problem, with higher than expected empty rates being a significant cost to your business, and reducing your ability to cull for milk production or quality. There are multiple reasons why your bulls may not perform as well as you would hope, including lack of bull power, poor AI performance, or poor fertility in your bulls.

There are several steps that should be undertaken to ensure that your mating performance of your bulls is optimized. One of these steps is to ensure that the bulls you are using over your cows are in good health and producing appropriate amounts of fertile sperm and that enough bulls are being used. Bull fertility testing is one way that this can be assessed in your bulls prior to mating.

Bull semen assessment is a quick and simple test that can be conducted on farm with minimal equipment and impact on the bull. All that we require to conduct the test is a set of yards where the bull can be restrained, we bring all the rest of the equipment. A full physical examination of the bull is conducted to ensure the bull is of sufficient body condition, in good health and has testicles of adequate size. A semen sample is collected from the bull. It is then immediately assessed under a microscope, where the quantity and quality of the sperm is assessed. This results in an immediate pass/fail grade being given to each bull.
There are multiple causes of poor semen fertility in bulls, ranging from genetic conditions through to short-term infertility following sickness or poor body condition. Without assessing the semen of a bull, it can be very difficult to identify a problem as they will continue to service normally if they have infertile semen, with the issue only being noticed with a high rate of returns, or not until scanning. With bull power having a significant impact on reproductive performance, it only takes one or two bulls to be infertile in a mob to result in issues with getting cows pregnant. Bull fertility testing is especially important when the cow to bull ratio is above 30:1 or only use a small number of bulls due to small herd size.

Date Added: Tuesday, 30th July 2019