Research and practical on-farm experience over the years has shown us that grouping cows according to age, nutritional needs and milk production at specific stages of the lactation can provide an economic benefit to many dairy farms. The dairy farmer who’s able and willing to group cows can do a more efficient and effective job of managing his herd. It opens the door for fine-tuning of feed rations, which has the potential to increase overall lactational performance and maximize income-over-feed-costs (IOFC) for individual groups. Properly formulated feed rations targeted for specific stages of lactation will result in a more productive and healthy cow.

Jeff Dunklee milks about 450 Holsteins on his family’s Vern-Mont Farm in Vernon, Vermont. The rolling herd average for the herd is 24,500 pounds. Dunklee keeps the milking herd divided into four groups: an early and late lactation first-calf heifer group, a high production group of mature cows and a late lactation group. He really stresses the importance of keeping the heifers in a separate group of their own. Keeping them away from the older, larger and more dominant cows gives them a much better chance of reaching their potential. Because of the way his barns are constructed, he’s able to separate the heifers into an early and late lactation group – enabling just that much more fine-tuning of the heifer feed rations.

Dunklee explains that the dairy puts a lot of effort into raising heifers and improving the genetics of the herd. The younger you can get your heifers into the milk barn, the fewer heifers you need on the dairy to sustain your culling rate. The average age of his heifers calving for the first time is currently about 23 months. The difference between having heifers calving at 27 months as opposed to 23 months adds up to a lot of extra heifer raising – and costs – every year.

The Vern-Mont facility is an older one and Dunklee says that if he had the opportunity to make changes or re-do things he’d also have a fresh cow group to better meet the nutritional needs of those cows in the first month or so of lactation. He also has a close-up dry cow group in which those cows are fed a close-up ration for three weeks prior to freshening.

Steve Couture is the dairy herd manager at the William H. Miner Agricultural Research Institute in Chazy, New York. Miner Institute has a milking herd of over 300 cows and was currently milking 280 cows in July. The herd was producing a 97 lb average (3X and Posilac). Couture said the herd is divided into a fresh group and those cows are kept there up to 20 days. First-calf heifers have their own group in which they remain for most of the lactation. A high group is kept up to about 150 days before being moved and the ration is balanced for over 100 lbs of milk. A mid group runs from about 150 to 200 days in milk depending on how milk production is holding up and a low group is balanced for 60 to 70 lbs of milk. According to Couture the heifer group has helped diminish the ‘sophomore slump’ that cows often have in second lactation. He stresses that the criteria for moving cows is dependent on both milk production and days in milk as well as how much room there is in a pen.

Grouping cows on a dairy isn’t an exact science. Producers can divide a mature cow’s lactation into roughly four stages: fresh, high, mid and low. Many are also discovering the advantage of keeping a close-up dry cow group to help transition the mature fresh cows.

A fairly straightforward way of grouping a milking herd can be:

•Fresh cows < 30 DIM

•High cows 30-100 DIM

•Mid cows 100-200 DIM

•Low cows 200 DIM to drying off

If you’re able to group heifers, they’re often left in a single corral for nearly the entire lactation, since milk production for heifers tends to be more linear rather than curvilinear.

Grouping cows doesn’t necessarily have to be limited to a large herd to get an economic benefit.

Steve Pechetti, the managing partner at Wrights Dairy Farm in North Smithfield, Rhode Island, milks about 100 cows. In 2003, he built a new freestall barn divided down the center with a feed lane, 50 cows on each side. Understanding the practical limitations of making too many groups in a small herd, Pechetti, today, keeps mature cows in early and mid- lactation on one side of the barn and first-calf heifers and late-lactation cows on the other side. He purchases one high protein grain mix and mixes it at different amounts in his TMR. The high group is balanced for about 90 pounds of milk and the lower group is balanced for about 65. Pechetti’s herd averages over 70 lbs of milk most of the year. He’s kicking around the idea of making a fresh group.

The central focus of grouping cows should be to maximize IOFC at each stage of lactation – in other words, getting as much milk out of the cow for a specific increment of feed cost. As a dairy cow progresses through her lactation, her nutritional needs change along the way. In order to get a cow to produce 25,000 lbs of milk, for instance, she needs a nutrient-dense diet at the start of the lactation – which often costs more – but she doesn’t require that same density later in the lactation when she’s six months pregnant and only producing 60 pounds of milk. Herein lies the rationale for grouping cows. A much less costly ration can be mixed for a tail-ender using less expensive feedstuffs.

If you’re in the process of planning a new facility or modifying an existing one, definitely talk to producers who are grouping cows as well as industry professionals such as nutritionists and vets for grouping strategies. You’ll find it advantageous to group cows according to milk production, DIM and even parity. Many will agree that there are economic advantages to doing so – when milk prices are low and when milk prices are high.

Some management items to consider when grouping cows:

•Watch body conditions in all groups so fresh cows don’t get too thin and late lactation cows get too fat. Adjust rations accordingly.

•When moving cows to a new group, try to move them in larger groups. Cows are social and they take longer to adapt to a new pen if left all alone.

•Make ration changes gradually to allow the rumen time to adapt.

•Work within the limitations of your facilities and avoid overcrowding.

•Avoid the temptation to micromanage the groups and changing rations too often – there still can be a large DIM range within a single group.

•Formulate a feed ration for a milk production level that is about 10 pounds over the highest milk producer in a given group. PD