Successful coaches do everything they can to make sure their teams are match fit before the season starts. A pre-season fitness test, pre-season training and appropriate footwear all contribute to a team’s readiness. The same applies to your bull team if you want to successfully use them for natural mating after AI. Local research conducted by Andy Hancock found 1 in 5 bulls tested failed a veterinary bull breeding soundness examination (VBBSE). Testing your bull team in the pre-season will ensure problems can be resolved before they impact on your herd’s reproductive performance.
Pre-season fitness test
Prior to joining we recommend that all bulls undergo a veterinary bull breeding soundness examination (VBBSE). This should be done 2-3 months before joining and involves both a physical and semen examination. The physical component involves assessing the ability of a bull to seek out and serve females on heat. This is done by assessing the head, gait, feet and legs of the bull to identify any potential risks to his serving ability. The reproductive organs of the bull are also examined as any abnormalities in this region are highly likely to be a risk factor for infertility. Semen is then collected and assessed immediately for the level of activity, and a sample is sent to the lab for assessment of sperm shape. Both of these factors have been shown to have a strong association with a bull’s fertility.
Select your bull team and have them on farm and grouped 2-3 months before joining. This allows the bulls enough time to sort out their social hierarchy before joining. Assess the bulls’ body condition which should be moderate. Supplements with additional vitamins and minerals may be needed if the bulls are too thin.
Lameness is a significant factor in bulls failing VBBSE especially at the end of joining. As a preventative measure, we recommend placing rubber blocks on all the feet of all your bulls to prevent lameness. The pictures at right show the wear and tear that can occur to blocks applied to a bull’s feet after only four weeks of joining. Imagine the wear and tear on the hoof if the blocks were not there.
All bulls to be used should be vaccinated to prevent vibriosis. Vibriosis is a venereal disease of which bulls are symptomless carriers. They spread the bacteria to cows and heifers during joining and it results in early pregnancy losses. As the bulls are normally the carriers of vibriosis in dairy herds, vaccinating the whole bull team 2-4 weeks prior to joining every year is an effective prevention method for the whole herd. Bulls should also be ear-notched to rule out Bovine Viral Diarrhoea Virus (BVDV) infection, as this can potentially reduce conception rates if bulls are infected during joining.
During the season
Bulls should be observed daily during the mating period to check for signs of illness, lameness and loss of libido. Sperm take about 70 days to develop in the testes, so any infections or inflammation that result in a high testicular temperature during mating have the potential to reduce a bulls semen quality and therefore his fertility for an extended period of time.
Rotation and replacement of bulls is important to reduce fatigue over the period the bulls are being used. The power of the bull team comes from having an adequate number of bulls available to serve the expected number of cows on heat. The current recommended ratio of bulls to cows is 3 per 100 cows to be joined (at the start of AI) and 4 per 100 if synchrony is used. Always have more than one bull in at any one time. There are many different rotation systems used by farmers, and the rotation policy must work for you. The important thing is that bulls are able to have a rest.
So when preparing for the bull joining period, consider your bull team as an elite sports team with you as the coach! It is important to have a good game plan. Call The Vet Group Farm Services to book your bull team in for a VBBSE, to have rubber blocks placed on their feet or if you need help with your plan.