Ioften hear producers complaining about twins. If twins are both born alive, are the same sex and you have a cow to foster one of the calves, life is great.
We all know the opposite picture – twins coming malpresented (mixed up). You finally get them out (with or without veterinary assistance) and both are dead. The cow doesn’t clean and then becomes a problem to rebreed.
Dystocias from fetal malpresentation are the biggest reason twins have a lower survival 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 all the legs and two heads coming backwards and forwards, it is no wonder there are mix-ups.
The original British breeds rarely twinned but with the advent of the exotics, better nutrition and other factors, twinning can reach eight per cent in Simmentals, Charolais and Holsteins. This creates a lot of extra calves. If they reach weaning that can definitely improve the bottom line. The key is getting them out alive, grafting one to another cow and then getting the cow rebred.
CAN BE A BENEFIT
U. S. research on a twinner population over the last 10 years has found to be a definite economic benefit for twins. They selected and kept cows with a propensity to twin and had over 60 per cent twinning, so knew to watch them closely and jump in when problems developed.
In a commercial operation there are a few clues to help us. Cows with any history of having twins should be monitored when they calve. Twinners should be pulled from the main herd and fed with the heifers where there is less competition, and where they can be observed more closely.
The most common presentation for twins is one backward and one forward. With the backward 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 first prevents 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 quick enough.
When calving twins, remember to follow the legs back to make sure they are from the same calf and the top calf is the one which must come out first.
THEY COME EARLY
Gestation for twins is about a week shorter than for a single birth so it is not uncommon to have a higher percentage of twins early in the calving season. To avoid missing twins, it never hurts to start observing cows one week before the first one is due.
Having an extra calf earlier is great because there will be 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 92 per cent of these heifer calves will be freemartins (very little development of the female reproductive organs) and will be sterile. Some freemartins you can definitely identify as the external genitalia are different with a prominent clitoris. Others look normal and may even cycle but will not breed. Because they possess more male influence, freemartins will 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 selecting them for replacement status as they will be in the upper 25 per cent for growth in the heifers. Mark their tag well with “Twin” or use a different-colour tag to avoid this mistake. When they are identified in the feedlot, freemartins do better implanted with the steer implants.
MONITOR THE COW
Any cows which deliver twins are more prone to certain clinical diseases. Retained placenta and metritis are the obvious ones and because they are generally more run down the immune system is compromised and conditions such as mastitis and ketosis are increased. If the cows are raising both calves, giving them better-quality feed, at least for the first few days, as well as an extra vitamin E, A and D shot, may help with retained placenta.
As mentioned earlier, a higher number will be treated for retained placentas. Watch for signs of depression and a fever which 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 results in fetal membranes not being expelled and the accumulation of micro-organisms. This combination or when extensive intervention at calving leads to metritis.
Since twins are earlier in gestation, the fetal membranes are immature so don’t release as quickly. This is why in almost all abortions, retained placentas are common as well. 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 get bred on time. There will be more open cows after twins or often they will take another cycle to get bred on average so it is imperative to provide this extra care post-calving.
I would be remiss to not talk about colostrum supplementation with twins. Postnatal survival is lower with twins and the greatest cause of this 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.
After a slow birth, oxygen-deprived calves may be kind of stupid and have a poor suck reflex. All this is where an extra supply of colostrum either saved from your herd or using the good-quality commercial colostrum is 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, as we can’t really prevent them, and do our best to save them, raise more pounds of beef and get their mothers rebred.