| ||Why is it so important to evaluate the effects of age and method of castration?
Bull calves are castrated to reduce meat toughness, aggressive behavior, sexual interest and dark cutting. However, the process of castration can be stressful and can lead to weight loss and lowered growth performance. The age and method of castration has a significant impact on growth performance and stress response making it important to choose the right age and method.
How does age of castration affect performance and stress response?
During puberty, the testes produce androgens that promote muscular development by increasing nitrogen retention. After castration, calves loose weight and their average daily gain drops. Studies have found that cattle castrated after puberty lose weight for up to 4.5 months. This weight loss is because of lower daily feed intake as well as the muscular developments of the young bull shrinking because of the natural testosterone withdrawal.
Castration close to birth reduces this weight loss. Calves castrated at birth achieve similar weights as calves left intact and castrated at weaning followed by a prolonged set back due to late castration. It is better to castrate calves at birth or a short period after birth because they recover quicker because of less stress.
Is it good to castrate bulls calves at weaning time?
No. To castrate calves at weaning time which is already a stressful time, often causes calves to succumb to sickness. By castrating well before weaning, stress can be handled better because it is spread over time.
What about the method of castration?
The two most common methods for castrating bulls are surgical and rubber banding. When using plasma cortisol concentrations as a measure of stress response, there is no significant difference between surgically castrated and banded cattle. However, when measuring Haptoglobin levels (a serum protein) to quantify discomfort, the surgical procedure causes higher levels. If done appropriately, banding is the less stressful and safer of the two options.
Is it advisable to band bulls 1-year or older?
Although banding bulls at 1 year of age or older is considered less stressful than surgery, both options cause significant stress to the animal. Rather than fitting the animal to the production system or the market place by castrating, it is often more profitable to change the handling system, feeding environment and marketing system to fit the intact animal, feeding and selling the animal as a bull.
When is the best time to castrate calves?
Calves suffer less when castrated earlier whether it be by banding or surgery. Any advantages to improved growth by leaving them intact as they get older is lost from losses due to stress from castration. As bull calves get older, banding becomes more advantageous than surgery.
Reference article: Bretschneinder, G. 2005. Effects of age and method of castration on performance and stress response of beef male cattle. Liv.Prod. Sci. 97, 89-100