You can help control calf birthweight

By Gary Sliworsky
OMAFRA Rep.

Calving time is very near or started already for some and with it comes some calving problems.
Some of these problems are caused by physical misalignment in utero and are unavoidable. However, problems caused by breeding large-birthweight bulls to heifers or small cows and calving overfinished heifers can be prevented.
First, recognize that some calving difficulties are acts of nature and you have no control over them. Legs back, head back, breech or backward presentations, and upside down are examples of calving problems you can do nothing about. No amount of selection, training, or calving knowledge helps to position the calf correctly before birth.
The factor you can help control is calf birthweight. It can be selected with a high degree of certainty. Expected Progeny Differences (EPDs), generated from thousands of records, take much of the guesswork out of bull selection. Small cows or heifers require smaller birthweight calves than do larger, mature cows. No selection system is perfect, and there may be the odd calf or two that is large, even out of a high calving ease bull. Remember that the frame type of the bull can also have an effect on potential calving problems.
In selecting for birthweight, try to use bulls with birthweights no larger than 9% of the mature cow weight, i.e., a 90-pound-birthweight calf on a 1,000-pound cow. This is the upper limit, and the cow would need to be a mature cow for this mating. A comfortable range would be 8%, or an 80-pound birthweight on a 1,000-pound cow. The objective is to get the largest live calf possible to be born without complications. Generally, the larger the calf at birth, the heavier it is at weaning.
When using EPDs, remember they are generated from within averages of breeds. An EPD of 0 for a Simmental bull is quite different from 0 for an Angus bull. Know the breed average for traits when using EPDs. That EPD of 0 for a particular bull may make a tremendous difference to the cow having the calf. It may mean the difference in an unassisted birth and one where there are problems.
Overfeeding young cattle can cause calving difficulties by causing the calf to grow too large late in gestation. High protein feeds have been implicated in large birthweights as well. You must balance feeding so you have the heifer in good condition without having her fat before calving.

Dates to Remember
Feb. 11 – Equine presentation and discussion by Nor-West Animal Clinic, 1:00 pm – 4:00 pm, Devlin/LaVallee Municipal Office