In any beef cattle enterprise, irrespective of the size of the herd, the identification and possible culling of unproductive stock is essential to maximise herd productivity. Pregnancy testing is one of the most important tools to achieve this.
Timing of pregnancy testing
Generally, the most convenient time for handling the cows is at weaning and pregnancy testing can be organized easily to coincide with this management procedure. Non-pregnant or ‘empty’ cows can be identified by ‘banging’ tails or by recording identification numbers. These cows can then be segregated and prepared for sale after weaning.
If you want accurate information on the stage of pregnancy, you will need to pregnancy test earlier, however. Between 6 and 12 weeks of pregnancy aging the stage of pregnancy is very accurate, as pregnancy progresses, the precision of aging is reduced and age will be given to the month rather than the week. Towards term a 7-week error can be expected, especially as there can be up to 3 weeks in variation in gestation length between individual cows.
Heifers should be pregnancy tested 7-8 weeks after bulls are taken out. Sufficient numbers of heifers should be retained for a short joining period and those that do not become pregnant should be culled at the time of pregnancy diagnosis.
Pregnancy testing enhances the economic performance of the beef herd in a number of ways. Earlier calves make more money and for every day the average calving date is shortened in a 100-cow herd, $200 is generated if 1kg live weight is worth $2.
A mature cow will consume 8kg of dry matter per day. Without pregnancy testing the cow will not be identified as empty until the end of the calving period, which may be 5 months or more from weaning. If pasture costs around 4c/kg, this equates to a minimum of $10 per month that the cow is costing while producing nothing. If hay is being fed, she is costing much more. Consultants in Southern Australia estimate the cost benefit per cow identified as non-pregnant is at least $100 per cow.
Surplus females can be sold to advantage if they are pregnancy tested in calf. As management improves, there will be a surplus of pregnant females and as the average age of the females in the herd drops, more surplus females will be suitable for sale as replacement breeders.
Pregnancy testing will allow identification of serious herd problems, including infectious disease, which limit fertility. It will also minimise serious financial losses.
Warrnambool Veterinary has a number of experienced veterinarians able to pregnancy test your cows and heifers. Many of our vets use ultrasound for pregnancy testing, but will manually recheck empty animals.