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Dairy Nutrition
The Forest for the Trees

by John S. Hibma

Many areas of the Northeast are heavily forested and very hilly. As one travels through the countryside, winding, climbing and descending, long, panoramic vistas are few and far between because the terrain and trees obstruct the view. There might be a lake or a field only 50 feet away, but a traveler won’t even know it’s there.

I recently went for an airplane ride with my pilot-friend, Dave. We cruised along in a single-engine Cessna and from our 1,500-foot perch we were able to enjoy a bird’s-eye view of the Connecticut River valley from Hartford, south to the Long Island Sound. With a little bit of altitude, one gets a completely different perspective of things, seeing where the river curves over here or how a forest is situated over there. You see the countryside from a different point of view.

One of the most crucial areas of management that’s very easy to lose sight of on a dairy farm is the herd’s days-in-milk (DIM). It can be a difficult number to keep track of and easy to forget about. When you’re slugging away everyday just to get the cows milked and fed; when you’re trying to stay ahead of the hay harvest and get the corn planted, herd management details get lost in the shuffle.

It starts innocuously with one bad pregnancy check. Then there’s another and another, and next thing you know you’re several months later with a whole bunch of cows that are still open. Today’s commercial dairy should have an average calving interval of 13 to 14 months as one of its management goals. Ideally, we would like to have cows calve as close to every 12 months as possible. Unfortunately, there are always cows in a herd that, due to undetected reproductive or metabolic problems, do not conceive in the desired 60 to 80-DIM time slot. Instead, they take three to six months or more to conceive, which then results in calving intervals of considerably longer than 12 months.

If you have a herd with an average calving interval of about 13 months, you will have an average DIM of about 165 days. What does it mean if you find your DIM at 180 or 190? It means you have a higher percentage of the herd in late lactation than in early lactation, and since cows in late lactation produce less milk than cows in early lactation, it understandably means you have a lower milk average than you would if those cows were in early lactation.

The place to start with keeping the DIM in your herd down is with the dry cow and fresh cow nutrition. Dry cow rations, more often than not, do have adequate energy, however, they are prone to be low in protein due to excessive levels of corn silage coupled with very low quality hay for many farms in the Northeast. Diets should be a minimum of 12 percent crude protein and preferably 13 percent with about a 50-50 split of rumen degradable and undegradable protein sources. As cows get closer to freshening, incorporating some anionic salts into the diet to help prevent milk fever and other metabolic disorders is highly recommended to keep cows’ rumen in top condition and ready to ferment the massive amounts of dry matter that she must consume after freshening.

There’s no question that adequate energy levels along with proper protein fractions, amino acid and mineral/vitamin balances will have an effect on a cow’s ability to conceive by the third month of lactation. With feed costs being the single biggest expense on a dairy, it’s tempting for a dairy farmer to trim a few dollars off of a feeding program with the hopes that it won’t adversely affect the milk production or the reproduction. At the risk of
sounding too cliché, you get what you pay for when it comes to ration costs. If you want the big milk and, at the same time, run a 13.5-month calving interval, you’re going to have to spend the money on proper nutrition.

Avoiding a prolonged period of negative energy balance for the fresh cow during the first two months of lactation should be a top priority for the transition cow diet. A healthy cow’s dry matter intake will usually catch up to her productive and metabolic requirements four to five weeks into the lactation. It isn’t unusual for a cow to pull down a full body condition score or more, as much as 200 pounds of body weight, during the first weeks of lactation, and it’s the dairy management’s responsibility to see that the cow is receiving adequate dietary energy levels that will in turn allow her to express a strong estrus even during the voluntary waiting period prior to breeding. An extended period of negative energy balance will first and foremost reduce milk production as the cow compensates for the lack of energy, but will also delay estrus and strong heats. A cow in a negative energy balance will not conceive.

Even though it should be a no brainer that cows won’t get pregnant if they don’t get bred, it’s pretty hard to ignore the fact that reproduction efficiencies and high DIM on many dairy farms is dismal simply because cows don’t get bred. All of the feeding programs can be the best but, if you’re breeding AI and heats are missed or if you’re using bulls to breed and they can’t do their jobs, the DIM in the herd will soar. Poor reproduction efficiencies on a dairy result in fewer fresh cows per year, more cull cows and fewer replacement heifers.

A dairy’s ability to maintain both adequate and consistent cash flow is highly dependent upon keeping a consistent and predictable number of cows freshening every month of the year. Don’t lose sight of the bigger picture by letting DIM get out of control. By regularly monitoring the herd’s average DIM and the size of the dry herd, and quickly responding to undesirable trends, a dairyman can avoid unpleasant surprises in his cash flow months down the road.

The author is a dairy nutritional consultant and works for Central Connecticut Farmer’s Cooperative in Manchester, Conn. Comment or question? Visit www.farmingforumsite.com and join in the discussions.