To get the most from the forage that goes into your dairy herd, evaluate what comes out. It could net you “free milk,” said Mike Hutjens, University of Illinois emeritus dairy nutritionist, at the 2012 Four-State Dairy Nutrition and Management Conference in Dubuque, IA.
Although manure tests aren’t always clear-cut and most are downright messy, they can show how effective feeding programs are, he said. Here are ones he recommends:
Fecal Starch Analysis
“I am a little biased; I think this is a great analysis,” said Hutjens of fecal starch testing. Considering today’s high corn prices, this $17-20 lab test can help producers optimize the amount of starch being digested. Penn State research suggests that fecal starch content should be less than 4.5% and that a one-percentage-unit change equals 0.67 lb of milk.
“So if I have a herd at 8% (fecal starch analysis) and I reduce it down to 4% because I processed corn silage correctly or I ground corn finer or let the corn silage age longer, that’s basically 3 lbs of milk added – not quite – and I borrowed from the manure. That’s free milk.
“If you start seeing corn in the feces, you’re going to see fecal starch over 10% levels.”
“What we are looking for is very subjective,” Hutjens warned. Nevertheless, manure washing allows producers to see just how well cows are digesting their feed and/or if feeds were processed correctly before being consumed.
He collects a cup of manure (500 grams) from several samples in a pen, pours it on a 1/8” screen and runs warm water across it.
If corn kernels remain, the corn silage or ground corn grain wasn’t processed correctly.
If fuzzy cottonseeds are seen – “you have to squeeze them because sometimes all you get are hulls” – count how many seeds there are. “If I’m feeding 5 lbs of fuzzy cottonseed and I see more than five or six whole seeds, then I think we’re losing some value. Is that a right number? I have no idea. That is my thumb rule.”
In that case, he recommends increasing forage fiber length to stimulate cud chewing, allowing cows to break cottonseed hulls.
If a manure washing leaves behind split soybeans, the soybean part of the next ration should be processed more finely. The seed should be broken into four to eight pieces, he added. This is more common with roasted soybeans, which are harder than raw soybean seeds.
Hutjens usually scores at least one third the number of manure piles as the number of cows, so probably 30-35 piles per 100 cows.
He evaluates how consistent the manure is using scores 1 and 5 as possible health problems, scores 2 and 4 showing the need to rebalance a ration and score 3 as optimal. He credits Michigan State University with the scoring system.
Manure with score 1 is very liquid – of pea-soup consistency, showing no rings or dimples and may have bubbles of gas. It indicates that the ration may have too much protein and/or starch or excessive minerals or low fiber levels.
Score 2 manure, at right, doesn’t pile and is runny, less than 1” deep with an appearance of rings. It also reflects too much protein and starch, excessive minerals, low fiber levels and/or cattle grazed lush pasture.
Manure with a score 3 is of porridge consistency, stands 1½” high and shows four to six concentric rings and/or dimples. It also shows the ration is balanced with an optimal rate of feed passage.
Score 4 manure is thick, doesn’t stick to shoes and shows no rings or dimples. It reflects a lack of degradable protein, excess fiber and/or low starch.
Score 5 manure is in firm balls and stacks 2-4” high. It indicates dehydration, a lack of degradable protein, excess fiber and low starch.
Hutjens uses the top two screens of the three-screen Nasco Digestion Analyzer, formerly called the Cargill Manure Screener. He feels he gains enough information from those screens to adequately rate the manure.
When evaluating high-group cows, he likes to see fewer than 5% of samples at score 1, fewer than 20% at score 2 and more than 80% at score 3.
More than 90% of samples in low groups should hit score 3 and less than 10% score2.
Manure scores could change slightly as lactation stages change. High-lactation and close-up dry cows should rate score 3, while dry and late-lactation cows can afford scores of about 3.5 and fresh cows can score 2.5, Hutjens said.
Check this short photo gallery called "An Interesting Photo Shoot ... Of Manure."