Evaluating forage options for dry cows

Noah B. Litherland, Extension Dairy Scientist

February 14, 2009

Dry cow nutrition might not be the first thing on your mind given current challenges facing the dairy industry. However, proper dry cow nutrition is critically important to improve success in early lactation. Cows fed appropriately during the dry period transition more smoothly, have fewer health problems, and are more productive. It is important to develop a dry cow diet(s) based on a sound forage program. Most successful dry cow diets consist of approximately 70 to 80% forages; thus, nutrients contributions from forages (excesses or deficiencies) partly dictate the success of dry cow diets. No single forage is ideal for dry cows; therefore, a mix of forages is needed to meet nutrient requirements in a total mixed ration. Dry cow nutrient requirements are quite different from lactating cows; therefore, a unique look at forage options is warranted.
A variety of forage options exist (see Table) including corn silage, alfalfa, wheat straw, cool season grasses, sorghum, and corn stalks. Optimal forages for dry cows should:

1. Be moderate in energy density
2. Low in potassium
3. Be palatable
4. Be processed adequately to minimize sorting
5. Be free of negative nutritional factors such as mold
6. Provide consistent quality
7. Provide bulk/fill in the rumen

Feeding diets that prevent dry cows from over-consuming energy appears to be advantageous in reducing a number of health problems in fresh cows. One of the challenges to feeding dry cows is to avoid over-consumption of energy. Dry cows do a poor job of moderating energy intake and will often eat in excess of nutrient requirements predisposing them to metabolic disorders such as ketosis, fatty liver, and associated disorders. Combinations of forages that contribute to moderate energy diets (0.60 Mcal/lb NEL) are advantageous. Forages that are high in potassium and other cations (positively charged minerals such as calcium and sodium) tend to cause hypocalcemia and milk fever.
Forages must be palatable and readily consumed with minimal sorting. If cows aggressively sort forages in favor of concentrate or finer particles, then the result is consumption of a diet that is more nutrient dense than that which was intended. Dry cow forages must be free of mold. Mold may reduce the efficiency of immune function increasing susceptibility to mastitis and metritis after calving. Forages that provide consistent quality are ideal as they contribute to uniform feed mixing and result in more consistent intake. Finally, forages that provide good rumen fill or bulk may be advantageous as they maintain muscular tone and volume in the rumen, maintain feeding and rumination behavior, and may reduce the incidence of displaced abomasum after calving.