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Springtime decisions impact dairy profit for the next yearLEXINGTON, Ky., (Apr 7, 2010)
Kentucky’s spring weather sometimes makes harvesting quality forages a challenge. Spring rains can delay harvest. And since most producers rely on forages for their dairy cows’ nutritional needs, the key is to make the most of Kentucky’s unpredictable weather.
“Starting a few days before the optimum stage of maturity allows you to harvest higher quality forages overall with only small decreases in yields,” said Donna Amaral-Phillips, University of Kentucky College of Agriculture dairy specialist. “These small decreases in yield result in more milk or growth per acre which greatly affects your bottom line. Ideally, you want to be one of the first of your neighbors (harvesting) in the field instead of the last.”
Dairy producers use forages as the foundation of feed rations for dairy cows and heifers. Then they add grains, byproducts, minerals and vitamins to complement the forages they feed.
“Generally speaking, 55 percent or more of a dairy cow’s ration dry matter comes from forages,” she said. “The higher the quality, the more forage you can feed, and generally the ration supports greater milk production at a more economical cost. With increasing feed costs coupled with lower milk prices, the importance of incorporating high quality forages has taken on even more importance.”
She explained that the stage of maturity at harvest greatly affects the quality of forages.
“This factor is definitely under management or your control,” Amaral-Phillips said. “As grass and legume plants mature, the percentage of leaves in the total plant decreases, while the percentage of stems increases. As a result, the digestibility or energy value of the crop decreases with advancing stage of maturity.
As a result, she recommends harvesting grasses and small grains, such as wheat and rye, at the late-boot stage of maturity, or just before the seed head emerges from the stem. Delaying harvest does increase yield slightly but can negatively impact milk production and heifer growth and the amount of forage that can be used in the diet because of lower levels of digestible nutrients.
In the past, 50 to 60 percent of many rations’ dry matter contents came from forages. In recent years, these percentages have been pushed beyond 60 percent or more, especially in lower producing dairy cow groups. Increasing the amount of forages fed has been successful when quality forages are available, Amaral-Phillips said.
“Quality forages provide more nutrients in every bite,” she continued. “So you need to feed less concentrate or grain to get dairy cows the nutrients they need to support milk production.
To determine the quality of any forage, a producer must send a representative sample to a forage-testing laboratory, where technicians will analyze its nutrient content. They can use the results to balance a least-cost ration for the cows in the herd. The higher the quality of forages available, the greater the amount of forage a farmer can use to balance a ration for a particular group of cows or heifers.
Amaral-Phillips said the quality of forages varies from year to year as well as from field to field in the same year. That means it’s important to take separate forage samples representing different cuttings and crops. Various factors determine the quality of forages, including temperature, rainfall, overall fertility, the species harvested (generally, legumes are more digestible and higher in crude protein than grasses), variety differences and the maturity stage of forages at harvest.
“You can control fertility as needed for growth of a specific crop through management,” she said. “However, changes in environmental temperature and rainfall are beyond your control. Varietal differences may impact the quality of forages, especially as they relate to NDF (neutral detergent fiber) digestibility.”
“Remember that the hardest nutrient to get into cattle of all ages is energy, therefore forage maturity, or the stage at harvest, greatly impacts the amount of forage you can effectively use in dairy cattle diets and still maintain milk production or growth,” she said.
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