Beef bulls are prepared in different ways before the upcoming breeding season. Some are ignored, maybe left on some distant stubble field or in a drylot pen, and inadequately fed. Other bulls are fed too well, so they waddle with fat. The rest are properly prepared for the breeding season, putting them in the best body condition to promote good fertility and get their cow herd in calf.
Whether these successful bulls are young or mature, they must maintain or achieve a body condition score (BCS) of 5.0-6.0 (one being thin and nine being obese) by the start of the breeding season. That’s because beef bulls in this optimum body condition have the highest viable sperm count and have high sex drive. To gain an even better premium on fertility, we should also segregate the young first-year bulls and returning two-year olds from mature bulls and put them on their own feeding program to gain weight into maturity.
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For example, for a group of mature bulls weighing 2,000 lbs., we want yearling bulls to weigh about 1,300 lbs. (65 per cent of mature weight). Two-year olds should weigh about 1,500 lbs. (75-80 per cent of mature weight) at the beginning of the breeding season. Such a growth rate of the yearlings will largely be based upon their adjusted autumn weaning weight, while two-year bull performance depends upon weight-loss recovery at the end of their first breeding season. In both cases, the daily weight gain is estimated to be about two to three pounds per head.
As a case in point, I have a friend who operates a 250-cow-calf operation and calves them in mid-March to the end of April. Bulls are released onto breeding pastures in early June and pulled by the end of July. (Note: A few weeks before the main cow herd is bred, calving-ease bulls are released to breed his first-calf replacement heifers). At the end of the last year’s breeding season, all bulls were separated according to stage of maturity by putting them on their own recovering hayfields until the first snowfall. Then, they were brought onto pastures near my friend’s home and overwintered on harvested forages, concentrates and a good mineral-vitamin program.
A nutrition program
A few months before the present 2023 breeding season begins, here are some dietary and related details on how my friend ensures all his bulls are ready to breed when the time comes.
1. Body condition of the bulls (as well as the entire cow herd) is evaluated. This allows time to increase the plane of dietary energy of all mature and young bulls, either to put back some BCS or increase the rate of growth.
2. A midwinter inventory of available forages is taken. Last winter, there was a feed shortage due to the previous year’s drought, which put my friend’s bulls (and cows) in less-than-adequate shape and fertility. This winter there is an adequate supply of good quality alfalfa-grass hay and barley silage.
3. Mature bulls (three years old and older) in fairly good shape are maintained diet of 58-60 per cent TDN and 12-14 per cent crude protein. Yearlings and returning two-year olds are moved to achieve optimum BCS by consuming a higher plane of 62-65 per cent TDN and 13-14 per cent protein.
4. The actual pre-breeding diet is really an extension of the overwinter program — mature bulls are fed alfalfa-grass hay, plus five to 10 lbs. of barley silage. Yearling bulls and two-year- olds get 30 lbs. of barley silage plus a couple pounds of barley. When weather gets cold and nasty, the dietary energy is increased — mature bulls may get a few pounds of barley added to their all-forage diet.
5. A fortified mineral/vitamin program is introduced to all bulls at the same time as their pre-breeding diet. My friend provides them with a breeder-type mineral fortified with chelated (more bio-available and retained) trace minerals and higher levels of vitamins A, D and E. He likes to refer to a classic Kansas State University study that fed zinc-methionine rather than regular zinc to breeding bulls, which resulted in a 33 per cent increase in sperm production.
Right now, the body condition scores of most of my friend’s bulls are in optimum body shape for successful breeding. Therefore, he is optimistic about the 2023 breeding season. High-fertile bulls will yield high conception rates throughout his cow herd, and each pregnant cow will eventually go on to birth and nurse a profitable calf in 2024.
