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ST. CLOUD, Minn. - With the high cost of corn, people are wondering whether starch can be reduced or taken out entirely of dairy rations. Randy Shaver, University of Wisconsin (UW)-Madison extension dairy nutritionist suggests that replacing corn starch with higher-fiber carbohydrates can work well in dairy rations and can save on feed costs. Shaver summarized research trials comparing reduced-starch rations with traditional levels of corn grain in rations and suggested feeding strategies during his talk at the Midwest Dairy Expo in St. Cloud, Minnesota.
"A lot of people are saying, 'Eight dollar corn! I can't feed any starch. Just take it out of there.' You can do that, but the last time I looked, milk was a pretty valuable commodity, too!" says Shaver. Switching to highly digestible fiber in the rations and taking the starch out can really impact production components, he cautions.
"I think there's a big paradigm shift in looking at diets, carbohydrates and the economics of feeding," Shaver says. "A question: 'If we were feeding 25-30 percent starch diets when we had $2 corn, what should we be feeding now - 25-30 percent or 18-20 percent?' We did studies looking at that question," he says.
Shaver summarized four continuous lactation trials conducted at the UW-Madison Arlington research station and a fifth Ohio State University study. The research focused on cows in the high group in mid and late lactations with the objective of looking at the effects of lower starch diets. The cows stayed on the diets for three to four months. The diets contained roughly 50 percent forage and replaced corn starch with fiber sources. Three trials used soy hulls, which are low in starch, are a very digestible source of neutral detergent fiber (NDF) and are similar in protein content to corn grain. The fourth study used a mixture of wheat middlings and whole cottonseed, says Shaver. The Ohio State study used "run-of-the-mill corn silage" to replace corn grain.
"In three of the four studies, we had had quite a substantial increase of dry matter intake, so when you hit those cows with a very digestible fiber source such as soy hulls and pulled out the corn grain, you had more digestible NDF and less starch. The high-producing cows said, 'We'll just eat a lot more feed, get the energy and keep milking.'" The cows, when not limited by fill, had a remarkable capacity to eat more feed to meet their nutrient demand, consuming a surprising 1.5 to 1.6 percent of body weight NDF. "This is a carbohydrate effect on feed intake," says Shaver.
Four of the five studies resulted in flat milk production levels between the normal and reduced-starch diets. Solids-corrected milk was either flat or reduced. Feed efficiency was not improved with the reduced-starch diets because cows ate more feed, so the cost actually went up, Shaver reports.
However, a more important profitability measure is income over feed cost, says Shaver. "We were able to reduce the cost per pound of dry matter by feeding the reduced-starch diet. The bottom line was that income over feed cost in all of the five studies was either neutral or positive," he says.
"If you look at feed intake and feed efficiency and get a handle on economics, I think you'll find that starch is a pretty important nutrient. With milk prices 18, 19, 20 or 21 dollars, I wouldn't toss the baby out with the bath water. Don't take a real sharp axe to feeding energy," Shaver says.
He also recommends 5 to 7 percent of total sugar in the ration as optimal for profitability in total mixed rations (TMR), based on a large group of studies which looked at sugars added to rations from several different sources. Be sure to look as the cost of the sugars versus the starch they are replacing.
Shaver urged producers to take a close look at feeding systems and ration grouping strategies in the face of high corn and protein prices. A one-group TMR for the herd's entire lactation is costing a lot more than when corn was lower-priced. Each dairy has its own set of circumstances relating to convenience of grouping strategies to feed different rations to various groups, Shaver says. He points out that if starch is too low in the one-group TMRs, you will restrict intake and production of the higher-producing cows.
Another factor to consider is Rumensin® levels, adds Shaver. "As you come in and drop starch content due to high-priced corn, I think there is room to feed Rumensin to improve feed efficiency," he says. In a study comparing Rumensin levels of 350 mg per day with 500 mg per day and with soy hulls replace corn grain to lower starch from 47 percent to 20 percent in the ration; the cows gained nearly three pounds per cow per day with the low starch, high Rumensin diet and had greater milk per unit of dry matter intake. Butterfat test was not significantly affected, Shaver says.[[In-content Ad]]

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