When an Idaho dairy producer recently was asked if he feeds straw, he blurted, “Are you crazy?”
He likely won't be adding straw to his TMRs anytime soon. But some producers do feed small amounts of it, and in certain situations, that's a wise move.
Straw's primary role is in dry-cow rations. But, if positioned properly, it also can work well in diets of transition cows and even high producers.
Straw can bring several pluses to a dairy feeding program:
If processed correctly, it can be a source of functional or long fiber to develop a forage mat in the rumen.
Low in energy, it can be used to dilute energy- and starch-rich forages (such as corn silage) in heifer and dry-cow diets.
Its low protein level (4% total protein, 25% soluble) makes straw a good fit for rations with high levels of protein-rich legumes. Diluting that highly-soluble protein can reduce the amount of excess nitrogen excreted in the urine.
According to the 2001 NRC, wheat straw is 1.5% potassium, 0.3% calcium and 0.10% phosphorus. That makes it well-suited for dry-cow rations where potassium and phosphorus levels must be watched closely.
Straw is a “clean” forage, usually with no mold or weeds.
But, any way you look at straw, it has some negatives:
Its high fiber content can limit dry matter intake. According to NRC, wheat straw contains 73% NDF, 50% ADF and 9% lignin.
Its low energy level — 47% TDN or 0.37 Mcal of net energy-lactation — is a big negative in high-producing dairy cow rations.
NDF digestibility is low, too, resulting in a high rumen fill factor.
Palatability can be a problem, leading to sorting.
Straw is high-priced and may not be available in your area.
Based on these characteristics, feeding straw could be considered under several scenarios:
Situation one: With continuous emphasis on forage quality and low-fiber corn silage varieties, the NDF level can be limiting. Brown midrib corn silage and forages with RFVs higher than 180 are almost “too good” for building a ration. Adding a small amount of straw might be beneficial.
Situation two: Your current forages don't provide enough long fiber to maintain rumen function. They were chopped too short, or the length was reduced by bagging or overmixing of the TMR. Adding straw can improve rumen pH and fermentation.
Situation three: Intensively grazed forages may contain over 28% protein (80% degradable) and less than 35% NDF. They rapidly clear the rumen, resulting in rumen pH below 5.5 using rumenocentesis (rumen tapes). New Zealand dairy managers reported that feeding 2 lbs of straw improved manure scores and increased milk yield and components.
Situation four: Close-up dry-cow rations should contain less than 1.2% potassium, while maintaining rumen fill. If controlling the potassium level allows the feeding of only 5 lbs of legume-grass dry matter, straw can provide additional long fiber to avoid displaced abomasums and acidosis at calving when feed intake drops.
Several dairy field nutritionists routinely add 1-1½ lbs of straw to all lactating and dry-cow rations. They consider straw as an insurance policy to maintain minimal rumen function and health.
But don't do it without carefully considering where it might fit in your program. Then limit the amount fed. Typically, 1-3 lbs/day is optimal.
The straw may have to be processed (1-2” long) to avoid feed sorting. If the cows don't eat the straw and it's needed to balance the ration, more problems could be created than solved.
The best type of straw to feed isn't clear. A top Pennsylvania dairy manager has tried several types and feels wheat straw works the best for that farm because of its hollow stems (they float in the rumen). Also, the cows seem to consume it more readily than other types.
Start by adding 1 lb of straw/cow to observe the response. The following responses would be good news:
Manure scores improve (going from loose to firmer).
Milk yield or components increases or returns to normal.
Dry matter intake remains the same or actually increases.
More cud-chewing activity is observed.
If any of these “cow characteristics” go the wrong way (dry matter intake drops, for example), the added straw is a liability.
Mike Hutjens is an extension dairy specialist at the University of Illinois, Urbana.