For many producers in the Mid-Atlantic states, the phrase, "If you don't like the weather, wait five minutes and it will change," became all too real this summer. Rainfall across the region was not only hit-or-miss depending on location, but it also was sporadic throughout the growing season.
For some producers, the summer's intense heat damaged the corn crop, but late-summer rains allowed for decent third and fourth cuttings of alfalfa. "Producers in one county may be short of forages, while other producers in neighboring counties may have enough or extra," says Virginia Ishler, dairy nutritionist at Penn State University.
If your forage harvest was less-than-expected this year, you may want to lower the amount of forage fed in order to stretch supplies and accommodate purchased feeds. Producers can successfully lower the amount of forage in the diet, says Maurice Eastridge, dairy nutritionist at Ohio State University. But, "management of low forage feeding programs must be very intense," he stresses.
When you decrease the amount of forage in the diet, you must pay close attention to the forage neutral detergent fiber (NDF) level in the ration in order to avoid a decline in milk production and possible health problems, such as acidosis. Here's what you need to know:
Don't dip below the minimum
While you can adjust the level of forage in your cows diet, there are limits. Too much fiber can make the ration overly bulky, reducing intake and milk production. In contrast, too little fiber can alter the fermentation process and cause acidosis.
The best tool to monitor the forage-to-concentrate ratio in the diet is the NDF level. NDF measures the total fiber in the ration and quantifies the amount of total fiber provided by the ration ingredients. As a general rule, the minimum amount of NDF in the ration should be about 0.95 percent to 1 percent of the cow's body weight. Of that amount, you don't want less than 0.75 percent to be from forages - if it is cut at recommended lengths. However, with finely-chopped forages - those less than the recommended 0.375-inch theoretical length of cut for corn silage and 0.75-inch cut for kernel-processed corn silage - you will have to increase the minimum amount of forage NDF in the ration. Depending on the chop length, this could be an increase of between two to five units, or a forage NDF level of about 0.95 percent to 1.25 percent of the cow's body weight.
In research trials, Eastridge has successfully fed cows diets with the forage NDF around 0.65 percent of the cow's body weight. But these low levels of NDF have only worked when high-fiber byproducts, such as whole cottonseed or soy hulls, were included in the diet and the starch level did not exceed 25 percent to 30 percent. (A starch level of 25 percent to 30 percent would roughly equate to a nonfiber carbohydrate level of 30 percent to 35 percent.) Be sure to talk to your nutritionist before trying to feed NDFs at this level.
If you decide to feed a low-forage diet, Eastridge recommends feeding it to mid- to late-lactation cows. Cows with a high propensity to go off feed - transition and early lactation cows - are more likely to develop health-related problems and experience drops in milk production.
Additionally, if you feed a low-forage diet, use a buffer. A low-fiber diet may lower the cow's cud chewing and, therefore, decrease saliva production. Add a buffer at the rate of 0.8 percent of the ration's dry matter.
Finally, you must watch cows closely when feeding a low-forage diet. Signs of trouble can occur quickly. Those signs include: varying feed intakes and milk production, inverted milk fat and protein percentages, an increase of displaced abomasums, sore feet and loose feces.
Although having less forage than you'd like for the year can be frustrating, using these guidelines can help you and your nutritionist navigate your herd through the year with minimal problems.
Help when purchasing feeds
If you need to purchase feeds to extend your forages this year, use feed evaluation factors to get the best ingredients based on cost and nutritional value, suggests Virginia Ishler, dairy nutritionist at Penn State University.
Feed evaluation factors compare price and nutritional value of a feedstuff with the "gold standard" ingredients of No. 2 corn, 48 percent soybean meal and alfalfa hay. Nutritionists have compiled tables that estimate the relative nutritional value of various byproducts and feeds when compared to these ingredients.
Ask your nutritionist to do some calculations for you before you make a purchase, or you can make those calculations yourself. To access the tables, go to up the Penn State dairy nutrition Web site at: www.das.cas.psu.edu/dcn/catforg/DAS/index.html
Keep forage NDF minimums in mind
|Forage NDF as a percent of body weight||NDF intake level|
|0.75*||Minimum if ration provides 1.3 to 1.4 percent total NDF by use of byproduct ingredients.|
|0.85*||Minimum if ration provides 1.1. percent to 1.2 percent total NDF by heavy use of grains or starch ingredients.|
|0.90||Moderately low forage intake level.|
|0.95||Average forage intake level.|
|1.0||Moderately high forage intake level.|
|1.1||Maximum forage intake level.|
* Requires adequate chop length on forages.
Source: "Feeding during shortages of home-grown feeds," Virginia Ishler, Penn State University, 1999.