Twins – a paradigm shift in beef cow efficiency is possible
Improving fertility has always been a major goal in beef production. Over the last 50 years progress has been made using genetic, nutritional and management methods. Many producers are having success in getting nearly one calf per cow per year but the question I would pose is, “Are we ready to move on to breed and manage a cow herd where most cows will have twins?”
A portion of the farming and animal science community has been looking at this for many years, perhaps framed around the observation that a ewe with only 2 teats and a relatively small udder will often rear two or more good lambs, while a cow with 4 teats and a larger udder rarely raises more than one calf at a time.
Over the last 30 odd years, research groups in Australia, New Zealand, France and USA have all attempted to increase twinning rate in beef cattle by genetic selection and all have made some progress. The most successful of these has been the US group at the Meat Animal Research Centre in Nebraska. This group achieved a 3% improvement in twinning per year in a composite herd which allowed the introduction of proven outstanding individuals of any breed, repeated direct observations of ovulation rate and good recording systems in a large herd. Cattle from this herd (USMARC Twinners) had the potential for a conception rate of up to 60% twins when we started importing them in 2004.
At Cavendish we operate a high fecundity commercial prime lamb flock and a relatively small commercial beef herd which we have been grading up to the USMARC Twinner line. Since we started this program we have had 390 matings of cows with twining bloodlines, with 35% of the calvings resulting in multiple births. This is genetic twinning so the matings are mostly by bulls using natural service or AI (without stimulants) when we need to bring in new semen from North America. We do watch calving quite closely, there are some difficult calvings but these are usually easily corrected and we do need to check that the mother takes both calves during the first couple of days after birth. Once the calves are 3 days old the herd can be handled as normal cows. This extra supervision is really no more than would be expected in most first calf heifer programs. These results confirm that the twinning selection that was done in USA is working here in western Victoria.
Over the period in our herd, the weaning weight of a twin calf is about 80% of that of a single calf. In other words a cow rearing twins produces 160% of the weight of a cow rearing a single. Furthermore, rearing a twin does not seem to reduce the fertility of the cow by very much if at all. We have generally put the steers into the weaner sales where they seem to match the other cattle entered in these sales for the range of weights, condition scores and prices in spite of including a high number of twin born calves.
In 2015 we had 59 cows calving and they produced 89 calves and 16 heifers who produced 19 calves, which means that for all the females that calved, the calving percentage was 144%. Calving commenced in March and the calves were weaned in November. The single weaner heifers weighed 287kg and the twins 253kg (88%). Excluding a couple of animals that were retained as bulls, the single born steers were 317 kg and the twins were 251kg (79%). Thus the average single rearing cow produced 302 kg of weaned calf while the average twin rearing cow produced 504 kg of calf. The 2015 results might seem slightly better than the long term average for our herd, probably because there are now more mature cows in the herd and the proportion of twinner blood has increased.
Thus in answer to the question I posed at the start, it is clear that we do have a herd which can produce a high number of twins and these do offer a dramatic improvement in the possible output per cow and overall herd productivity.