The Cow-Calf Manager

Livestock Update, October 2004

John B. Hall, Extension Animal Scientist, Beef, VA Tech

Managing Reproduction with Fall Nutrition

This summer has been provided adequate forage for most cattle operations. However, even in well managed operations, young spring calving cows (2 & 3 year olds) will often come in at weaning in lower body condition than is optimal for the winter. Cows that are thin going into winter require more feed because they lack insulation provided by body fat. In addition, cows need to be in body condition 5 or 6 by next calving season for optimum calf health and cow reproduction.

Fall calving cows need to maintain weight between calving and breeding. Young cows need to continue to grow during the fall. Nutrition during the fall is critical to a successful breeding season in this winter.

Autumn is the best time to increase body condition because abundant forage and temperate weather conditions are conducive to rapid weight gain. The goal for spring calving cows during the fall should be to get mature cows into BCS 6 before the cold wet weather of winter begins. For feeding or grazing management, cows should be divided into two groups ­ 1) mature cows in adequate body condition and 2) thin mature cows and young cows.

Forage fits the bill
Stockpiled Fescue. In the Mid-Atlantic States, stockpiled fescue is an excellent source of nutrition for both spring and fall calving cows. Research from Virginia Tech indicates that the nutritional content of stockpiled fescue meets or exceeds the nutritional needs of all classes of cows except lactating 2-year old cows. Stockpiled fescue averages 60 % TDN and 11% crude protein.

Just after the calves are weaned, spring calving cows will gain weight rapidly on stockpiled fescue. Cows can easily gain 1.5 to 2.5 lbs per day on stockpiled fescue during this time (mid-gestation). Thin cows and young cows should be allowed to graze separately from mature cows. Another alternative is to graze thin and young cows on a pasture until 50% of the forage is gone then move them to a new pasture. Then allow mature cows in good condition to graze the remaining forage in the pasture the thin and young cows left.

Mature lactating fall calving cows will generally maintain body condition on stockpiled fescue. If stockpiled fescue is still available at the beginning of the breeding season, cows will benefit by continuing to graze during the early breeding season. Even with stockpiled fescue, young cows will need some supplementation to prevent excessive weight loss between calving and breeding. Supplementing young cows with 5 to 6 lbs /cow/day of corn gluten feed or soy hulls will maintain condition through breeding.

Hay and supplement. Not every operation may have stockpiled fescue. Dry conditions or lack of available pasture for stockpiling may require producers to use hay-based diets in place of grazing. For mature dry cows in good condition, most average first cutting hay will provide sufficient protein and energy to meet their needs. Young cows or thin cows will require hay plus a supplement. Some example diets are given in Table 1.

Table 1. Diets to help dry cows gain weight

	Diet Composition (lbs. per cow per day as fed basis)
Ingredient	Diet 1	Diet 2	Diet 3
Fescue Hay	19.5	18.0	10.0
Corn	6.0	0	0
Soybean meal	0.5	0	0
Corn Gluten Feed or soy hulls	0	7.0	16.0
Days to gain 1 condition score	46	57	27
Cost per cow per day	$1.00	$0.89	$1.04

Lactating cows may require considerable supplementation (Table 2) depending on hay quality. These cows need to be fed the best hay on the farm, if grazing is not available. The diets in table 2 are designed using medium quality hay (56% TDN and 10 % Crude protein). Second cutting hay may require less supplementation. However, a forage test need to be taken to insure the correct supplementation is used.

The diets in Table 1 & 2 are example diets. For the most accurate ration development, producers need to test their hays for nutrient content and consult their county agent or nutritionist for help in designing diets.

Donšt overlook minerals
Mineral programs are best designed around your forages and feeding practices. Many county cattlemen's groups have worked with Virginia Tech or consulting nutritionists to design mineral supplements for their areas. However, there are some general recommendations for mineral supplements for fall nutrition.

Calcium, Phosphorus and Magnesium. In most cases, the standard 2:1 calcium : phosphorus ratio should be in the mineral mix, especially for lactating cows. When significant amounts (5+ lbs) of grain or by-products are fed then the grain portion of the diet will provide most of the phosphorus needed. Producers should switch 4:1 calcium to phosphorus mineral mix.

In the fall, all cows should receive a mineral mix that contains 12%-14% magnesium to prevent grass tetany. This is especially important for lactating cows. Because magnesium is unpalatable, producers need to check to make sure cows' mineral intake is sufficient.

Trace minerals. There are many trace minerals in most mineral mixes, but only a few are critical to reproduction. Selenium should be included at a minimum rate of 52 ppm. Copper recommendations have increased to 1000 to 2000 ppm. Zinc levels should 2000-3600 ppm. Soils in the Mid-Atlantic region tend to be high in iron so supplemental iron is not generally recommended.

Fall nutrition is a critical part of reproductive management. Mistakes in feeding during this period can be detrimental to reproductive performance of the herd. On the other hand, fall is an excellent time to access high quality pastures. Paying attention to nutrition now will make winter feeding much easier.

Table 2. Lactating cow diets

Diet Ingredients	Meets or exceeds needs	Increase or loss of body condition in good weather
17.5 lb hay + 14.5 lbs of soy hulls or barley	Yes	+1 BCS in 110 d
16.5 lbs hay + 13.5 lbs corn + 2.2 lbs soybean meal	yes	+1 BCS in 60 d
16.5 lb fair hay + 14.5 lb dry corn gluten	Yes	+1 BCS in 180 d
8.8 lb hay + 22 lb dry corn gluten	Yes	+1 BCS in 60 d, very high energy diet needs to be fed carefully
8.8 lb hay + 95.2 lbs wet brewers grain	Yes	+1 BCS in 175 d; cows may not be able to eat that much brewers grain
36 lbs hay	NO	-1 BCS in 90 days

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