Glacier FarmMedia – Dairy farmers give their cows 50 to 60 days off each lactation, but research suggests a shorter period could make sense for farmers and cows.
Barry Bradford, a dairy management and nutrition professor at Michigan State University, says in some circumstances, cows will perform well with 40 to 50 days of dry period.
More important, says Bradford, are the days of gestation. Cows that carry a calf to full term can handle a shorter dry period, but cows that calve early with a short dry period can have difficulty performing at the same levels as herd mates.
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Cows are given a dry period for the involution process to occur in the udder, preparing it for the next lactation. Researchers who did not give cows any dry period found that the milk volume in the next lactation is significantly reduced.
Physiological change requires different nutrition in the last four weeks of gestation and it makes sense to separate cows to feed them differently in that period.
At the recent Western Canadian Dairy Seminar in Red Deer, a poll of the audience during Bradford’s presentation indicated 80 per cent of farmers still use a 50 to 60 day dry period.
Problems caused when cows calve early hasn’t been factored into many previous studies.
Bradford’s doctoral student, Katie Meyer, looked at about 900 cows over 16 herds in the United States and found that problems were mostly with short gestation cows, not short dry periods.
Cows with short gestations, around 270 days, were 34 per cent more likely to be removed from the herd in the first 60 days of lactation compared to longer gestation cows, who carried the calf on average 277 days or more.
“In our data set, we really found very few reasons to be concerned about the short dry period length, if we accounted for short gestations,” said Bradford.
There were no effects on milk production, although fat production was suppressed.
There are several reasons that cows have short gestations, including selection for calving ease. Cows with twins calve five days earlier on average. Heat stress can cause early calving and cows that have inflammation, which indicates greater stress, can calve earlier.
Bradford says research also highlighted the challenges with long dry period cows that had an average gestation. These cows are more likely to be fat. In fact, some research suggests a short dry period or no dry period could help over-conditioned cows avoid metabolic diseases.
Cows that produce at a high level going into their dry period could also use a longer dry period, says Bradford.
Farmers should be able to target a dry period of 45 to 50 days, says Bradford, and not worry about it. Cows are calving earlier and many farm management programs default lactation length to 283 days, when most cows calve by 277 days.
