|Noah Litherland, dairy nutrition specialist with the University of Minnesota, advocates the use of wheat to reduce energy levels in dry cow diets.
It's far too easy to let dry cows get fat. After all, most of their daily amusement comes from bellying up to the bunk.
With too much palatable alfalfa or corn silage in the total mixed ration (TMR), it's not long before cows are packing on the pounds. And good things never happen to fat cows.
"Dry cows do a poor job of moderating their energy intake,” says Noah Litherland, a dairy nutrition specialist at the University of Minnesota.
"The forages on most dairy farms are too nutrient-dense for dry cows. Dry cows, if allowed to, will consume 30% to 60% more megacalories than their bodies require,” he says.
"Excessive energy intake, in turn, may lead dry cows to be metabolically lazy,” Litherland says. Too much energy in the dry cow diet cascades into a host of challenges:
There is no
- Insulin resistance that is similar to Type 2 diabetes in humans.
- Increased body fat mobilization metabolized through the liver, which can lead to ketosis and fatty liver.
- Reduced feed intake, causing secondary metabolic and health disorders.
one correct way to feed dry cows, Litherland readily admits. But the more he works with high-bulk, moderate-energy diets, the more he's convinced they are the way to go for most producers.
The key ingredient in many moderate-energy diets is a low-energy, bulky, palatable forage. Wheat straw fits the bill in many cases. "The high neutral detergent fiber level of wheat straw allows cows' rumens to fill up, but cows stop eating before they consume excessive amounts of energy,” Litherland says.
The typical dry cow diet shoots for 30 lb. of dry matter intake daily. No more than 30% of this, or 9 lb., would be wheat straw. Often, it's even less—4.5 lb. to 7.5 lb./cow/day.
"Dry cows have all day to stand around and sort the TMR for particle size,” Litherland adds. So to prevent sorting, the straw must be processed to less than 2". Wheat straw should be processed first in a tub grinder before adding to the TMR mixer. It should also be the first ingredient loaded into the mixer to further process and ensure adequate mixing.
If your nutritionist uses a Penn State shaker box, a good thumb rule is that 10% to 15% of the straw should remain in the top pan, and at least 50% in the bottom.
Weigh-backs should be less than 10% different from the as-fed diet in both particle size and nutrient composition. Weigh-backs greater than this suggest dry cows are sorting and likely consuming too much energy.
Wheat straw diets
|To prevent sorting, straw should be processed to less than 2".
also tend to dry out quickly. That can be a problem if rations are fed once a day, and even more so if dry cows are fed once every two days. Consider adding water to the TMR to adjust the dry matter to about 50%. Some producers use liquid mineral/protein supplements in the TMR to hold the diet together.
Other straws can also be used. In order of preference, Litherland likes wheat, barley and then oats. The barley and oat straws are more difficult to process. Oat straw tends to be higher in potassium and protein, is more rapidly digested and has a faster rate of passage—all things that are negatives in a dry cow ration.
Some producers have tried soybean straw, but it doesn't process well. It's either too coarse, which allows sorting, or it pulverizes into dust with too much processing.
Cornstalks also can work. But they're often contaminated with dirt and they have high ash content, which affects digestion and can even disrupt the immune system. Cornstalks are also often stored in round bales outside and are prone to moisture wicking, which results in mold. While they can work in winter, Litherland suggests switching to straw when the weather warms up in spring to avoid problems.
feeding straw diets throughout the dry period. Then, three weeks prior to calving, add anionic salts and your prefresh minerals for the close-up group.
He also recommends keeping 1 lb. to 1½ lb. of straw in the fresh cow diet. The straw adds rumen fill and diet consistency, which is a good thing as cows transition from dry status to lactation. Litherland suggests keeping the straw in the fresh cow diet for three weeks after calving. Avoid diluting the energy of fresh cow diets too much, since energy is critical to avoiding ketosis after calving. DT
OTHER FIBER SOURCES
If straw is unavailable, other forages can be used. Here are the pros and cons of each.
Pros: Adds moisture; low in protein, calcium and potassium; highly palatable.
Cons: May be too high in starch and energy; low fill factor, high sorting. Should not provide more than 50% of forage dry matter to avoid overconditioning.
Pros: Low energy and starch; moderate calcium, potassium;
Cons: High in ash; low moisture; easily sorted; molds can be a problem.
Pros: Moderate energy, fill factor and minimal sorting.
Cons: High protein, potassium and calcium; limit to 30% to 50% of forage dry matter.
Pros: Moderate protein, energy and potassium; sorting is less an issue than with dry hay; low calcium.
Cons: High in potassium if orchardgrass (2%), leading to high dietary cation-anion difference (DCAD).
Pros: Moderate protein and energy; high fill factor.
Cons: High in potassium; high sorting; is sometimes more difficult to process.
Pros: High in moisture; moderate energy and starch; low in protein and calcium.
Cons: Can be high in potassium; less digestible.
Soybean stubble hay
Pros: High fiber; moderate energy; low starch.
Cons: High to moderate potassium; high calcium.
Pros: High fiber; low energy, calcium and protein; palatable.
Cons: Possible rapid rate of passage.
Pros: Low energy, starch, potassium and calcium.
Cons: Low bulk effect; rapid rate of digestion and passage.
Diets During Far-Off and Close-Up Dry Periods Affect Periparturient Metabolism and Lactation in Multiparous Cows
More about Noah B. Litherland