Working towards short dry periods

Shortening the dry period to 40 days is one strategy being tried in a high yielding herd to reduce cow stress around calving. In addition, producers Peter and Mike Jones of Parc Gwyn Farm near Abergavenny are boosting their cows’ immune system by starting to feed just one dry cow diet throughout the dry period. Their aims are to improve the health of freshly-calved cows and reduce the incidence of metritis, as well as put more milk in the bulk tank.

Last year, the 160-cow herd averaged 10,600kg – and a metritis rate of 26 cases/100 cows/year. This is actually half what it was previously and it is a figure that has dropped even further to 21 cases, after high levels of vitamin E were added to transition diets. However, the incidence rate is still higher than the target 15 cases/100 cows in a high yielding herd, says the farm’s vet Rob Smith of Abbey Vet Group in Abergavenny. The herd doesn’t have a big problem with retained cleansings causing metritis, says Mr Smith, it is more a stress issue relating to nutrition at a time when the cow’s immune system isn’t up to scratch.

“Going to a shorter dry period with a single dry cow diet is all about lessening stress and maintaining energy balance in these high yielding cows. We need to boost the immune system, not compromise it. When it is compromised at, or around, calving, the cow is more susceptible to infection of the uterus,” he explains.

“We thought that if we shortened the dry period, Peter and Mike would get extra milk in the tank, as cows milk on for longer.  In addition, we could give dry cows one diet of only moderate energy density for 40 days.  Simplifying nutrition means no change in diets or groups at a sensitive time. This reduces social stress on cows, increases dry matter intakes and, hopefully, we have happier healthier cows which get back in-calf.”

One relevant factor in this herd is that Peter Jones thinks cows being on a diet too high in energy density for too long damages their udders. In other words, the suspensory ligament gives out as calving approaches, so that cows’ udder conformation is severely disrupted. Mr Smith thinks too much milk stacking up in the udder ruptures the ligaments and this physical effect leaves the cow with permanent udder damage. Feeding a higher energy diet for longer periods could also lead to overfat cows at calving, he adds.

Having only started short dry periods this summer, Mr Jones says it’s early days to report any major results. “Although we’ve had no problems with ketosis since shortening the dry period., we haven’t calved 20 cows yet on the new regime. Because we have a fair few twins born, which can easily appear 10 days early, we aren’t doing the whole herd on a 40-day dry period, just 75% of cows and will see how it goes,” he says.

With cows now milking on for longer, he hopes they will naturally reduce daily yields themselves. A key issue with drying off high yielding cows is that they are often still giving 30 litres/day. “I wait until they are yielding below 20 litres/day, but sometimes we have to change their diet onto straw to reduce yields, although we don’t like doing this too often.”

Newly dry cows at Parc Gwyn were typically moved into a bare paddock and onto a diet of straw, silage and minerals. Two weeks before calving, they switched to the transition ration. Now, Mr Jones and Mr Smith are working on a single dry cow ration, to be fed right through the 40 days, that incorporates the same ingredients (forage and straights) as used for milking cows, just in different quantities. “We will keep the high levels of vitamin E, plus maize silage, grass silage, chopped straw, a protein source, magnesium chloride and a dry cow mineral to provide a low DCAB diet of 10 MJ ME/kg DM energy density,” adds Mr Smith.

Mr Jones is using Cephaguard® DC (which is licensed for dry periods as short as 35 days) together with a teat seal at drying off. This means cows are fully protected from mastitis when dry, without risking an overlong milk withdrawal period. “It’s been working well as far as mastitis goes, so far, we have had no problems,” he says.

Mastitis is a key issue when cows are only going to be dry for a short period. Although there are benefits to taking two weeks off the conventional dry period, Mr Smith still thinks some cows need a longer rest between lactations. “When a cow is fit and in reasonable condition (score 3), it won’t hurt to drop to 40 days, but only when she’s not had lots of mastitis during lactation. If she has, it’s better for the udder to rest and repair. Really short dry periods (less than 35 days) don’t give the cow enough time to rest and prepare for her next lactation, or the udder chance to repair. There is also a major chance that a high cell count infection won’t be cured in such a short dry period. This has to be balanced by the fact that with shorter dry periods, cows are less likely to pick up new intramammary infections.”

Equally, thin cows or those carrying twins need a longer dry period for a rest.  And with twins calving a bit prematurely, cows could end up dry for just three weeks, he points out. “Problems also arise when calving dates are inaccurate: there might be repercussions if calving 2-3 weeks early on a 40-day dry period. But short dry periods have definitely got a place and could well help improve production efficiency in the right herds with the right cows. As long as records are accurate and cows are fit and healthy, the concept is relevant whatever the breed or yield.”