One of the lessons I have learned while dairy farming is to feed a high-fiber, low-energy diet to dry cows before they calve.
These dry cow diets typically contain finely chopped golden wheat straw. When delivered correctly, this dry cow diet maximizes rumen, or stomach, health before and at the time of calving, which benefits the cow as she begins producing milk. Not too much energy, not too little fiber … but just right in terms of outcomes; hence the name the industry uses to refer to it, the Goldilocks diet.
Cows are ruminants, designed to eat forages. In the rumen, longer stems consumed float on the top of rumen liquid, creating a fiber mat. The cow burps up masses of forage from the mat, and chews them (chews her “cud”). In doing so, she macerates the plant material further and exposes more of its surface area to bacteria and protozoa when it is swallowed back to her rumen.
These microscopic “rumen bugs” (bacteria and protozoa) digest the fibrous forages, making fatty acids, amino acids and so forth that will be absorbed by the cow as nutrients from her diet. It is critical for a cow to eat adequate fiber in the dry period to maintain an optimal rumen mat, which in turn plays a role in optimal digestion during lactation.
During the dry period, the cow is on a 60-day vacation from daily milking. Research has shown cows produce more in their next lactation when they have a dry period. The dry period allows for an involution of milk secretory tissue and a subsequent preparation for production again, moderated by the hormones of pregnancy and calving.
Nutritionally, our goal during the dry period is to maintain existing body condition of the cow and provide nutrients she needs for herself and her calf. The cow will gain overall weight as her fetal calf grows larger, but we want her body condition (fat stores) to stay constant.
When we look at feeds to feed the dry cow, the first two parameters we evaluate are energy and potassium levels. We like to make the dry cow total mixed ration, or TMR, low in energy concentration to drive pounds of intake but not body fat gain. Using feed ingredients low in potassium helps lower the incidence of milk fever at calving.
The feeds we typically have stored for feeding milking cows aren’t what we feed to the dry cows. Corn silage has too much energy too be fed free choice. It is typically low in potassium, however, so small amounts can be incorporated into the dry cow ration for energy and moisture. Alfalfa hay or haylage has too much energy and very high levels of potassium, so it is not included in dry cow rations. Grass hay can fit the bill, but it is difficult to get enough.
Wheat straw is a forage that can fit the bill: low in energy and potassium, relatively palatable, and available in a consistent quantity. Our dry cow diets consist of wheat straw, sudan grass baleage, a protein/vitamin/mineral mix and a little bit of corn silage. We feed our close-up dry group additional rumen-protected amino acids, and this helps fresh cow performance considerably.
Optimally, straw should be finely chopped to prevent sorting of the ration at the feed bunk. We buy straw which has been processed through a rotary combine, therefore its stem length is already shorter than straw run through a conventional combine. On our end, we change knives in our mixer regularly and mix batches long enough to assure the straw pieces are delivered to the cows in short, uniform lengths.
The ultimate test for a dry cow feeding program is fresh cow performance. The Goldilocks diet works. We have been feeding wheat straw diets to our dry cows for almost to 10 years. The wheat straw contributes to the rumen mat and helps transition the newly calved cow to the high energy lactating diet.