DRY FACTS A shorter dry period reduces stress and health problems for cows, and means you can produce more milk with fewer animals
Shorter is better when it comes to the dry period for dairy cows, says Daniel Lefebvre, general manager of Valacta, the centre for excellence in dairy production for Quebec and the Atlantic provinces.
“The recommendation to dry cows for 60 days between lactations has been wrong for several decades,” Lefebvre told attendees at the recent Western Canadian Dairy conference.
“This might not be adapted to today’s dairy cows, which produce a lot more milk. When we come to dry them off 60 days before calving, they’re still producing quite a bit of milk.”
This is stressful for the cows, said Lefebvre who recommends a short dry period of 35 days.
During the conventional 60-day system, rations are changed several times — there is a late lactation ration, followed by a fall-off ration high in forage, then a close-up pre-calving ration 21 days before calving, and finally a lactation ration. Each change causes stress in a cow, said Lefebvre, including stress to the mammary gland during dry-off, nutritional stress with each ration change, and physiological and environmental stress from being moved into a new pen or group.
In the 35-day system, cows do not go through the fall-off ration and move directly into the close-up ration close to calving. Fewer transitions equals less stress, researchers from Laval University and Agriculture Canada found in a study of 13 commercial herds in Quebec. In one study, 800 cows — half coming out of their first lactation and half mature cows — were divided into two groups, with one undergoing the conventional 60-day program and half a short dry period. The latter were less likely to suffer ketosis and had a decrease of Plasma NEFA. Mature cows in the short dry period had an increase in retained placentas, but this didn’t seem to cause any reproductive problems. There was a slight decrease in cows with udder edema in early lactation and producers saw less shrinkage of the udder for cows that were dry for a shorter period of time. There was no difference in the rates of clinical mastitis in either system.
Cull rates lower
There were fewer cows culled in lactation in short dry-period management, while reproduction rates were unaffected. And, critically, you need fewer cows to generate the same economic performance.
“It’s more expensive to feed her, but you get extra revenue so it’s a profitable strategy,” Lefebvre said. “If you’re over quota, then that’s a different story. This is a management tool that can very easily apply to the current situation of the farm.”
When implementing this system, it’s critical to use a single dry-period ration during the entire period and cows should be moved from the lactation ration to the close-up, pre-calving one. Lefebvre recommended producers aim for a dry period of 35 days as research has found periods of less than 30 days increases mortality rates, reduces production, and ups the risk of antibiotic residues in the milk.
Some cows simply can’t transition to a 35-day dry period and should remain on the conventional cycle, said Lefebvre. Cows that produce 20 kilos of milk 60 days prior to calving are the best candidate for the short dry cycle. Cows going into their first dry period can also be included in the short dry period cycle, as they tend to produce more milk in their first lactation.
Lefebvre stressed the importance of maintaining accurate breeding records and well-balanced rations. Gradual ration change is preferred over abrupt ration change.
“Minimizing stress and maximizing comfort is the key to the short dry period cycle,” he said.