In my practice I often hear producers complaining about twins, mainly because we do sometimes focus on the negative aspects of them. Research has been done on twins over the last 10 years in the U. S. and there were found to be a definite economic benefit. I will try and clarify the positives, negatives and outline how with some small changes you may improve the cost benefit of twins.
There is no doubt twins are great, if they are both born alive, are of the same sex and you have a cow to foster one of them. We all know the opposite picture with twins malpresented (mixed up) at birth, and when you finally get them out (with or without veterinary assistance) both are dead and the cow doesn’t clean and then becomes a problem to rebreed. If we can minimize the bad in this scenario and come up with more positives, twins would be a welcome addition to any herd. Keep in mind they will always require more care and attention and management than single calves.
The original British breeds rarely twinned but with the advent of the exotics, better nutrition and other factors twinning became more commonplace. They can reach eight per cent of births in Simmentals, Charolais and Holsteins. This creates a lot of extra calves which if they reach weaning can definitely improve the bottom line. The key is getting them out alive, grafting one to another cow and then getting the cow rebred.
Dystocias from fetal malpresentation are the biggest reason twins have a lower survival rate at birth. Twin or triplet lambs and kids are seldom mixed up at birth yet calves commonly are. When one ponders all the permutations and combinations of eight legs and two heads coming backwards and forwards it is no wonder mix-ups occur.
In the U. S. where researchers selected and kept cows with a propensity to twin, they had over 60 per cent twinning so they knew how to watch them closely and jump in when problems developed. In a commercial cattle operation there are a few clues that help us.
Twins often drag down a cow’s condition so they should be pulled from the main herd and fed with the heifers where there is less competition and they can be observed more closely at calving. Cows with twins have ovulated two eggs or an egg has split resulting in identical calves. Genetically these cows have a high likelihood of doing it again. You often hear farmers say this cow has had three sets of twins in the last four years or she twins every second year. These are very common scenarios so cows with any past history of having twins likewise should be monitored more closely when they calve.
The most common presentation for twins is one backwards and one forwards. With the backwards presentations the likelihood of a full breech (tail first) is increased and these often require veterinary intervention. These are a great loss if the breech birth is preventing the second calf from being born and both are born dead. With breech births the cows appear in first stage labour for a long period and often don’t initiate calving quickly enough.
When calving twins out; remember to follow the legs back to make sure they are from the same calf. The top calf is the one which must come out first.
Twins have a shorter gestation by about a week than a single birth so it is not uncommon to have a higher percentage of twins early in the calving season. It never hurts to start observing cows one week before the first one is due to avoid missing twins.
Having an extra calf earlier is great because there will be an opportunity to foster one. If a cow loses one right at calving, rub the placenta on the calf to be grafted. If this fails any of the other tricks including placing the skin of the dead calf over the live one can be attempted. This method works very well if an older calf dies and its smell is transmitted to the transplanted calf.
Half the time twins are mixed sex and 95 per cent of these heifer calves will be freemartins (which have very little development of the female reproductive organs) and will be sterile. Some freemartins can be identified by their different looking external genitalia with a prominent clitoris. Others look normal and may even cycle but will not breed. Because they possess more male influence, freemartins grow very well, like a bull calf. Producers generally will graft the freemartins and often the fact they were a twin gets lost in the shuffle.
A common mistake is to select them as replacements because they will be in the upper 25 per cent for growth in the heifers. Mark their tag well with “Twin” written on it or use a different coloured tag to avoid this mistake. In the feedlot, when they are identified, freemartins do better when implanted with steer implants.
Any cows which deliver twins are more prone to certain clinical diseases. Retained placenta and metritis are the obvious ones and because the cow is generally more run down her immune system is compromised and the chance of them developing conditions such as mastitis and ketosis is increased.
If the cows are raising both calves, at least for the first few days, giving them better-quality feed as well as an extra vitamin E A & D shot may help with retained placenta. As mentioned a higher number will be treated for retained placentas. Watch for signs of depression and a fever that may indicate metritis.
Twins often extend the stretching limit of the uterus and it does not contract as well or as fast after calving. This can result is fetal membranes not being expelled and the accumulation of microorganisms. This condition, or extensive intervention at calving that sometimes happens with twin births, can lead to metritis.
Twins being earlier in gestation the fetal membranes are immature so they don’t release as quickly. This is why on almost all abortions retained placentas are a common consequence. Work done several years ago showed using GnRH or prostaglandins at two weeks after calving may get these cows cycling earlier and allow them to be bred on time. There will be more open cows after twins or they will often take another cycle on average to get bred, so it is imperative that they receive this extra care post calving.
I would be remiss if I did not talk about colostrum supplementation with twins. Postnatal survival is lower with twins and the biggest reason is insufficient consumption of colostrum. Perhaps the cow only mothers the first or second calf or simply has not produced enough to supply both calves. Slow-birth oxygen deprived calves may be kind of stupid and have a poor suck reflex. Those are times where an extra supply of colostrum saved from your herd or a good quality commercial colostrum will be a real benefit to improving the survival of twins.
More pounds of calf weaned per cow exposed is definitely possible if more twins are saved. The other negatives can be counteracted with good management and a little more work.
If purchasing twin bulls for breeding keep in mind birth weight is not relevant and they will not have more of a propensity to twin but their heifer offspring at breeding will. Let’s welcome twins. We can’t really prevent them, and if we do our best to save them we will raise more pounds of beef and get their mothers rebred on time.
Roy Lewis is a cattle veterinarian with a practice at Westlock, Alta.