by Elizabeth A. Tomlin

Forage has a huge impact on dairy herd productivity and Cornell Cooperative Extension’s Central NY Dairy, Livestock and Field Crops team presented a forage quality program to advise crop producers on updated trial results in producing forage.

The program featured Dr. Jerry H. Cherney, Forage Specialist, Cornell /Soil & Crop Sciences; Dr. Limin Kung, Professor & Chair of Animal Science, University of Delaware, and Pro Dairy’s Dairy Forage Systems Specialist, Joe Lawrence, along with CCE CNY Regional Field Crop Specialist, Kevin Ganoe and CCE CNY Regional Dairy Specialist, Dave Balbian.

“Really there’s two parts to this,” said Ganoe. “Part of it is getting quality made in the field and once we’ve achieved that quality, what can we do to maintain it so we keep that quality getting through back to the animal?”

Cherney addressed growing high quality forage, with a focus on alfalfa and alfalfa-grass mixtures.

“We did a survey and somewhere between 85 and 90-percent of the alfalfa sown in New York is sown with grass,” reported Cherney. “That’s also true for New England and probably northern PA, the rest of the country probably averages less than 10-percent.”

Although studies imply that outside of the northeast, the majority of the USA has low interest in alfalfa-grass, Cherney reports that European forages consist mostly of grass legumes — not because they don’t have suitable land to grow alfalfa, but because of higher feed quality.

In the northeast alfalfa-grass is sown primarily because land conditions are not perfect for alfalfa.

“From a yield stand point, in the northeast, alfalfa-grass tends to out-yield alfalfa. That’s maybe not true on soils that are not quite so fertile, but if you’ve got any kind of good fertility on a field, alfalfa grass is probably going to out-yield alfalfa here. If you’ve got a fertile site, that dry matter yield can be one-tenth of a ton to four-tenths of a ton higher for every 10-percentage units of grass that’s in that stand. So, the more grass the higher the yield — especially where the grass can get the fertility and get the nitrogen,” explained Cherney.

Studies and feeding trials at Cornell and in Wisconsin show that feeding alfalfa-grass will produce as much milk as pure alfalfa, and alfalfa-grass mixtures can maximize forage content and balance rations, while generating higher milk production.

Neutral Detergent Fiber (NDF) used to measure of fiber in dairy feed analysis, was studied to determine impact of higher grass intake.

“As you go to more forage, or to a higher milk production, it becomes more and more important that you know exactly what you’ve got for fiber content. Things we are concerned about are fiber and digestibility,” said Cherney.

Grass has higher total fiber and NDF than alfalfa. “If you look at fiber digestibility or NDFD you see 20 to 25-percent unit difference between grass and alfalfa. That’s pretty big! That’s a lot more fiber and a lot more fiber digestibility in grass.”

Cherney favors meadow fescue over other grass varieties as an alfalfa-grass for several reasons.

“Grass species matters. Meadow fescue is more palatable and is higher quality than most of the other grasses that we deal with.”

Meadow fescue has also been averaging 10-percent higher in fiber digestibility than other grasses. “Right now, in the northeast, meadow fescue looks really good to me. We’ve got more to analyze this year and we’re going to see if it keeps looking that good, but it looks really good so far.

Studies show that a percentage-unit of NDFD is equal to about a half-pound of milk, per cow, per day.

“There have been one or two studies that say it is more like 1-pound, rather than a half-pound, but we’re going to go with this conservative number.”

So, what’s the potential economic advantage of adding alfalfa-grass to your feed?

“Based on $17/cwt, if you’ve got 1,000 cows in your herd, you could potentially make over $100,000 more money in milk,” Cherney said.

Joe Lawrence spoke to attendees about corn silage and quality.

“Corn silage is a forage,” said Lawrence, explaining that making selections when considering corn silage hybrids to produce quality is critical.

Trials performed by Cornell have provided some results on hybrid selection. However, Lawrence has a word of caution to producers.

“The first thing I will say to you is the wrong way to use those trials is to go to our tables and just pick out highest ranking hybrid at one location and call that company and say that you want that seed. That can lead you the wrong way really fast if you don’t understand the context of why that hybrid did so well at that location. Did it just do well at that location because of the growing conditions? Does it consistently perform well across multiple locations?”

Yield is important, but you definitely can’t ignore quality and the digestibility of fiber in the cow.

“If you harvest really high yielding grass, headed out orchard grass is going to be really high yielding, but a lot of that is not even digestible to the cow, so it’s taking up space in the rumen, passing through her, she’s not getting any nutrient value out of it. So think about it in terms of, what’s our yield of digestible material?”

How hybrids interact with the growing environment has an impact on digestibility.

“A hot, wet summer would indicate it’s going to be a lower digestible forage,” said Lawrence.

Research from Dr. Mike VanAmburgh examining five different corn silage samples, with essentially identical NDF numbers, showed a great discrepancy in the digestibility of the samples.

Lawrence explained trial results using charts and graphs. “We’re fairly used to looking at the 30-hour digestibility number. And generally we want a higher number because that means it’s more digestible.”

However, uNDF/240, a relatively new addition to the indicators, is now considered important, as well. “It stands for undigested fiber after 240-hours in the rumen fluid. It’s still undigested. So, we want a lower number here.”

Studies have discovered that the 240-hour number, even though fiber is not in the cow that long, is a good predictor of dry matter intake.

CCE CNY Regional Dairy Specialist, Dave Balbian clarified.

“Think about all of the cows in your herd. Dry cows, pre-fresh, fresh cows, high producers, low group; which cow does the feed stay in the longest? The dry cows! You’re going to get more value per-pound of dry matter the longer it’s in the cow. In a high producing milking cow it’s going to vary. It may not even be 24 hours. Different material is going to pass at a different rate. I think the third hour number was designed to replicate an average as far as retention time. But, the highest producing cow in your herd that’s eating a huge amount of dry matter is getting less value per-pound of dry matter because the rate of passage is high. The 240-hour number matters because it affects gut fill and it affects intake. And if you can get an extra pound or two of intake in a typical high group TMR, it’s worth about 2 to 2 ½ pounds of milk. So, driving that intake is pretty valuable to you.”

Lawrence said because of weather impacts to hybrids, producers need to focus on what works best in their region. Utilize information published from recent trials and consider what the growing season was and what the hybrid performance was for your region. Then work with whatever seed company you are working with before choosing hybrids to see how they line up with those results.

Dr. Limin Kung, a specialist on silo management, spoke to attendees on maintaining quality through proper fermentation and preservation of silage. 

“Whatever comes out of the silo really starts in the field,” said Kung. “But, how you manage it in the silo can damage it.”

Dry matter losses from mismanagement include delayed filling after chopping, poor packing and not covering silage immediately and completely — overlap plastic coverings by about 5 feet and cover with weight. Oxygen is an enemy to your silage; so, all possible air entryways must be guarded.

“Air can by eliminated by fast filling — but not too fast, even distribution of forage in the storage structure, chopping to correct length and ensiling at recommended dry matter for specific storage structures,” said Kung.

Methods of preserving different types of silage were discussed.

Clostridial management is another important factor to consider.

Feeding silage too soon will not benefit your herd. Kung reported that recent studies from the University of Wisconsin suggest that “high-moisture corn does not reach peak rumen starch digestibility until about 7-8 months of storage!”

“Hopefully you have enough carry over that your not feeding green silage,” commented Lawrence. “Hopefully you’re not feeding the new crop until at least Christmas time.”