With four out of every five calves born on beef farms sired by a stock bull, bull fertility is very important, writes Catherine Egan, Teagasc Beef Specialist.
The stock bull on your farm is key to maintaining a compact calving period, maximising the genetic potential and value of the calf crop, and overall herd profitability.
Key considerations include:
- A bull’s fertility status can change from year to year. Therefore, it is good practice to have a fertility test carried out on the stock bull prior to the start of the breeding season. It is estimated that 25% of stock bulls are sub-fertile. The cost of the test is very low when compared to carrying empty cows for the summer, and results are available to you before the technician leaves the yard.
- A bull must be able to maintain body condition score (ideally BCS 3), repeatedly mount and serve cows for 12 weeks and have a long working life in the herd. If you have bought a bull, find out from the seller what diet and current concentrates he is being fed and vaccinations he has received.
- A blood test might be useful to check for BVD, IBR, Johne’s Disease and Leptospirosis. If vaccinating or treating for parasites, these should be administered at least six to eight weeks in advance of the breeding season as they could lead to reduced fertility. Consult your vet for advice on the health of the bull. Remember a young bull in his first season should serve no more than 20 cows.
- It is important to avoid sudden changes and not to over feed the bull, as this can reduce fertility and lead to feet problems. He needs to be fit, but not over-fat.
- In advance of the breeding season, check feet and legs well and take remedial action if required.
- Watch the bull working to check he is serving cows correctly.
- If possible, rotate bulls or scan cows early so that an infertile bull or sub-fertile bull can be identified early.
- Record when you see a cow being mated and watch for signs of cows coming on heat repeatedly.
- If a large number of your cows are repeating, you need to take action to find out what is wrong. You must be prepared to start using AI or if you have a second bull with another group of cows, he may be utilised to serve more cows.
- Pregnancy scanning - when it is at least 35 days since the last cow in the herd could have been served then you should consider scanning the cows. It offers many advantages:
- Firstly, it will identify which cows are in calf and cows that are not in calf. This will allow you to cull empty cows instead of expecting these cows to calve next year.
- Secondly, most scanners are able to give you a good estimate of the number of weeks that each cow has gone in calf. This is extremely helpful when a stock bull is used on the farm to identify expected calving date.
- Thirdly, if the scanning reveals, for example, that more than 5% of your cows are empty then this may signify that there is a fertility problem in your herd. Maybe it was a bull issue or perhaps a mineral deficiency or a disease problem. Either way, it should prompt you into investigating the issue further.
Vigilance key
It is important to be vigilant and keep records during the breeding season. Every year we hear of unfortunate stories on farms when a farmer finds out their bull is not working. You think it will never happen to you. Every autumn, this is the situation some farmers find themselves in. Upon scanning, the result shows that a high percentage of the cows are not in calf. Hence, it is important that this year in particular to keep records and carry out a scan if you think there is an issue.
Also read: 3 important things to consider as turnout and breeding meet
