ORANGE CITY, Iowa — Winter is a time when cow-calf producers direct their attention to calving and developing replacement heifers. But, herd bulls are often a second thought until spring appears and the breeding season is just around the corner.
Now is the time to carefully manage your herd bulls so they are ready for the breeding season. Bulls should be body condition scored just like cows. Body condition score (BCS) ranges from 1 (an extremely thin animal) to 9 (a very fat animal). Ideally, a bull should have a BCS of 5.5 to 6 on this 9-point scale before breeding season.
The difference between two scores is about 90 pounds. So, if the bull this fall is a BCS 5, he will have to gain 90 pounds to achieve a BCS 6. This weight gain should be gradual (1 to 1.5 pounds per day). At one pound per day, it will take 90 days for the bull to improve one body condition score.
Aim for optimal condition six weeks or more before the start of the breeding season. Bulls that are too thin during the breeding season are less active and will not breed as many cows and heifers. This will reduce breeding success.
Age and BCS have a major impact on scrotal circumference. A larger circumference is positively related to fertility. However, excessive fat in the scrotum can negatively affect semen quality. Semen quality is reduced for bulls in a BCS 7 or greater or those with a BCS less than 4.
In addition to optimal nutritional management, bulls should be maintained in facilities with wind
protection and plenty of bedding. The bull’s ability to withstand cold is dependent on a clean, dry hair coat. Bedding is absolutely necessary to prevent sore feet and frost-bitten scrotums — both of which will reduce the number of pregnancies in the upcoming breeding season.