Managing bulls after the breeding season

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Source: Ontario Ministry of Agriculture, Food and Rural Affairs

Over the course of the breeding season, bulls can lose between 100 and 200 lbs. of weight. To achieve a tight calving pattern that will deliver both a uniform crop of calves and a calf per cow per year requires a breeding season of around 63 days. This means that for a mature bull running with 36 or more cows at any one time, there is little time available for feeding and resting during this intensely active period. It’s completely understandable that after this level of exertion that post breeding recovery can take between 4 and 8 months. A good recovery period is essential for bulls to be fit and ready for next year’s breeding season. Post breeding recovery is important for all ages of bulls but special attention to this recovery should be given to young bulls that are still growing (i.e. those less than 36 months).

Mature bulls that are in good condition at the end of the breeding season will easily recover any weight lost through access to good quality grazing followed by good quality winter forage (i.e. hay) without the need for grains or other supplementary feeding. Target hay quality of around 8% to 10% crude protein. The aim is to get bulls into ideal body condition score, i.e. 2.5 to 3, for the start of the breeding season but not fat. Over-conditioned bulls at the start of the breeding season will have low sperm counts and display lower breeding activity than a bull in ideal condition. Bulls that are thin at the end of the breeding season may need some supplementary grains to help with weight recovery – the amount of grains will depend on the nutritional quality of grazing and other forages available after the breeding season.

Young bulls are still growing so they need access to good quality grazing after the breeding season. Grain supplementation may or may not be needed depending on the quality and quantity of high-quality pasture available. Body condition scoring and feed testing is important prior to the start of the winterfeeding period. From those results a winter-feeding program can be formulated so that the young bull can gain 1½ to 2 pounds per day depending on the magnitude of weight loss during the breeding season. Winter diets should target around 10 – 12% crude protein level.

Producers who run two calving seasons (spring and fall) often are in the situation of double using their bulls. In this situation bulls must recover their body condition in the short time between breeding seasons. In these situations, its important producers plan for the post breeding management of their bulls and ensure both high quality pasture and supplementary grains are available to get those bulls back into shape as quickly as possible. Young bulls may not be the best choice for this type of system as they would potentially have to gain over 2½ lbs. per day to recover body condition between breeding seasons, depending on the weight loss incurred.

Where bulls are maintained in a coral or indoors post breeding, adequate space should be provided to allow the bull to get exercise. Daily exercise is necessary so that the bull has built up the stamina to put in the distance required during the next breeding season. Simply placing water and feed at opposite sides of the barn or coral will force the bull to walk between stations, thereby getting the necessary daily exercise. Be careful when putting multiple bulls together after the breeding season – introductions should be done slowly to avoid fighting.

It’s critically important for a successful breeding season that the performance of breeding bulls is examined closely while they are with the cows. Pay close attention to herd estrus behavior; note cows that are mated and if they show estrus again approximately 21 to 45 days later. Identifying and rectifying a situation where a bull that may be infertile or have sub-clinical fertility is critical to ensuring a good breeding season. Such a situation may require the replacement of the bull with another bull or using timed AI to save the current year’s breeding season and to avoid issues with subsequent breeding seasons.

There are several factors that must be considered when making decisions around culling a beef bull. The main reason beef bulls are culled is for reproductive failure, which, unfortunately, is sometimes only recognized when cows are scanned. This can have a significant negative impact on next year’s calf crop and a significant negative economic outcome from reduced calf sales. It is therefore imperative that the breeding herd is watched for breeding repeats to quickly prevent a subclinical bull becoming a breeding disaster.

Other culling decisions relate to issues of age. As bulls age they become less active and their breeding performance declines. Health issues is another common culling criterion, particularly related to feet and legs, which should be examined after the breeding season. If injuries have occurred, these should be treated, and it should be determined if they will heal adequately enough to enable the bull to perform well next year. Where treatment is not likely to be successful, this should be determined early so decisions around next year’s bull can be contemplated. The movement of older bulls move should also be observed to determine if arthritis is becoming a problem.

Where beef cow culling practices revolve around retaining home produced heifers, bulls will need to be culled to prevent inbreeding. This necessity is less of a problem on farms that run multiple bulls, but good breeding records must be maintained to prevent inbreeding.

Producers should also note the degree of dystocia (calving difficulty) that can be attributed to an individual bull. In some cases, this may not be obvious initially but over time as the cow herd changes as new breeding females with different genetics enter the herd, dystocia may become a problem. The primary cause of dystocia is fetal-maternal mismatch, i.e. the calf being too big at the time of calving to be born easily. Birth weight, which determines size, is strongly genetically determined by the male line.

The temperament of bulls can change and an initial quiet bull may become aggressive and dangerous over time. No matter how good the quality of calves or the number of calves that a bull produces, an aggressive and dangerous bull must always be culled from the herd, and the sooner the better.

Finally, producers should also consider the quality of calves being produced. Although a lot of emphasis is placed on the capacity of the cow to breed a good quality calf, it must be remembered that 50% of that quality comes from the bull. Producers should carefully consider if the poor quality of calf produced is a bull or cow factor. One of the ways to identify this is to examine the quality of calves produced by that set of cows bred to the bull. Where the overall quality is good, any poor-quality calf is likely to be related to the genetics of the cow rather than the bull. Where the vice versa though is true, the decision to cull will depend primarily on economics, i.e. will a new bull increase the quality of calves sufficiently to justify the cost of acquiring that new bull.

Once the breeding season ends, it’s important to start getting breeding bulls back in good shape. In most cases, access to good quality grazing followed by good winter forage is all that is required. The end of the breeding season is also a good time to think about the role the breeding bull plays in the overall breeding program. Consideration should be given to such factors as bull health, presence of daughters in the herd, bull temperament, history of calving difficulty and calf quality when making decisions around culling. Ideally, decisions around culling should be made as early as possible once the breeding season is completed to allow as much time as possible for research into and finding the ideal replacement.

References:

Field, J. and Anderson, N. 1985. Beef Breeding Season Management. OMAFRA Fact Sheet 85-054. Accessed July 6th, 2020.
Greiner, S. 2010. The Rules of Yearling Bull Management. BEEF Magazine. Accessed July 6th, 2020
Halfman, W., 2016. Bull Management 101 for Breeding Season Success. University of Wisconsin-Madison Beef Information Centre. Accessed July 3rd, 2020.
Rasby, R., 2012. Management of Young Bulls Before and After the Breeding Season, Cattle Production, University of Nebraska-Lincoln. Accessed, July 3rd 2020.
Selk, G. 2020. What to do with the Bull after the Breeding Season? Beef 2 Live. Accessed July 3rd, 2020.

Author: James Byrne, Beef Cattle Specialist, OMAFRA

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