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Forage Nutrient Quality a Concern

06 June 2011

US — As wet weather continues to delay the alfalfa harvest in some areas, Purdue Extension specialists say the crop's nutritional value for livestock feed is on the decline.

"The greatest concern is that with each passing day, the crops that should have been harvested lose quality," said Keith Johnson, Purdue Extension forage specialist. "As alfalfa and other forage crops mature, the cell wall content increases, leading to lower digestibility, palatability and dry matter intake for livestock."

The per cent neutral detergent fiber, or NDF, is a quality factor that can be used to predict how much of the forage an animal will eat. For high-quality alfalfa hay, the NDF is approximately 40 per cent. Johnson predicts the NDF for most Indiana alfalfa hay likely is closer to 50 percent. With a higher NDF value, less forage will be consumed.

For example, an NDF value of 60 would result in an unexpected dry matter intake of 2 per cent of body weight, while an NDF value of 40 would be about 3 per cent. Thus, a 1,200-pound cow would eat 24, and not 36, pounds of dry matter per day.

Johnson recommends hay growers have their hay quality analyzed.

"Producers need to get real numbers," Johnson said. "They may find out it's of inferior quality, but they also might find out it is still in a very acceptable range. Having hay analyzed puts farmers in a position to use best management practices and provides buyers with analytical data in addition to visual information."

A Purdue Extension beef livestock expert said that livestock owners should be proactive and know the nutritional content of hay they make and buy.

"The hay producers are making or buying in the next few months is going to be the winter feed supply," said beef specialist Ron Lemenager. "If that hay doesn't meet the cow's nutritional needs, farmers will have to buy supplements."

Lemenager said that supplement prices historically are lower in the summer, so livestock producers should consider forward contracting for energy-rich supplements like corn gluten, soybean hulls and distillers' grains.

"Producers should calculate which supplements are the most cost effective per unit of energy or protein," Lemenager said. "The hay quality has decreased with each day's delay in harvest, so now we have to make the best of a bad situation."

Johnson and Lemenager agree that forage growers should take advantage of warm, dry weather if they have the labor available. When farmers make hay, effective harvest management practices that get the cut crop off the field without rain damage can reduce the possible transmission of a disease to regrowth.

Johnson urged farmers to reduce field traffic by making a few key lanes for driving, especially if the soil is still wet. Excessive driving through the field can cause more soil compaction and damage the plants' crowns, which allows for the possible entry of disease organisms.

Growers can find out more about quality analysis from the National Forage Testing Association,

TheCropSite News Desk

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