Feed Potential Unlocked - Enzymes Can Be the Key

When used properly, newly developed enzyme formulations have the potential to help your cows produce more milk without more feed by digesting it more thoroughly.

Enzymes are proteins that catalyze or facilitate chemical reactions. They are essential for digestion as they break down feeds into their chemical components such as glucose and amino acids. The cow then uses these components directly or through microbes in her rumen.

Most enzymes are highly specific. They break specific chemical bonds in a specific feed nutrient. So, the digestion of a feed such as alfalfa requires the activity of literally hundreds of unique enzymes.

Enzyme names usually indicate the basic nutrient, or substrate, that they digest. Protease enzymes, for example, digest proteins, cellulases digest cellulose and xylanases help digest hemicellulose, which has a xylan backbone.

Each type of enzyme has a specific structure. This is crucial to its ability to bind to a specific nutrient substrate. The enzyme acts like a key, fitting into a matching lock to open or start the chemical reaction. This enzyme structure can be damaged by exposure to low pH, high temperatures of pelleting, or digestion through contact with protease enzymes. If the enzyme is badly damaged, the activity decreases. The key will no longer fit the lock to initiate the chemical reaction.

Commercially prepared enzymes are routinely added to poultry diets to supplement enzymes secreted by the bird’s own digestive system and improve feed digestibility. Until recently, there was little research on enzymes for cattle, except in their use as silage additives.

For cattle diets, enzymes must bind specifically to feeds and be resistant to rumen degradation. Since the primary digestible components of forages are cellulose and hemicellulose, recent research has focused on enzymes specific to these nutrients.

Researchers at the Lethbridge Research Centre of Agriculture and Agri-Food Canada are working with an enzyme formulation high in cellulase and xylanase activity but low in amylase, a starch-digesting enzyme. The formulation used was Xylanase B from Biovance Technologies Inc., Omaha, Neb. This product is now available in concentrated form called Promote N.E.T. It’s licensed in Canada and distributed by Agri Brands Purina Canada. Cost is about 17 cents per cow per day.

The enzyme was added to the concentrate portion of a total mixed ration (TMR) during a 12-week lactation trial. Milk production for cows on the enzyme-treated diets averaged 39.5 kilograms per day, compared to 35.9 kg for the control cows, a 10 per cent improvement (see table). The enzyme treatment significantly improved digestibility of both dry matter (DM) and neutral detergent fibre (NDF). DM intake did not change, and this may have created a shortage of other nutrients, resulting in decreased milk components, particularly fat.

Study One from Rode, Yang, Beauchemin, Journal of Dairy Science 82:2121, 1999

Study Two from Yang, Beauchemin, Rode, Journal of Dairy Science 82(Supp. 1) 122, 1999

In a second dairy trial, feeding the enzyme increased milk yield in mid-lactation cows. These cows ate a diet containing alfalfa cubes, barley silage and 45 per cent concentrate on a DM basis. Milk components and dry matter intake were not affected by the enzyme treatment. Increased milk yield resulted directly from increased total tract NDF digestibility (see table).

A trial by D. Kung Jr. and others on this topic appeared in the January 2000 issue of the Journal of Dairy Science. Several levels of a cellulase-xylanase enzyme, from Finnfeed International of Marlborough, U.K., were sprayed onto forages before they were combined with concentrates in a TMR.

In the first year, the highest level of enzyme resulted in a significant decrease in milk protein. Reducing dosage levels in the second year resulted in improved milk production without significantly affecting milk composition or DM intake. The researchers concluded that enzyme sources and dose levels are of critical importance.

David Schingoethe and others applied a cellulase-xylanase enzyme mixture to the forage portion of a TMR based on 60 per cent corn silage and 40 per cent alfalfa hay. Using a 55:45 forage-to-concentrate ratio, they tested an untreated control and three enzyme dose levels, also using an enzyme mix from Finn-feed International. Another control ration was an untreated 45:55 forage-to-concentrate diet. Cows averaged 121 days in milk, but they ranged from 38 to 204 days in milk at the start of the experiment.

Cows fed enzyme-treated forage during the first 100 days of lactation produced nine to 15 per cent more milk and 16 to 23 per cent more energy-corrected milk than cows fed the control diet. There was no production improvement when cows were in mid-lactation at the start of the experiment. Production responses in the 55:45 enzyme-treated forage groups were similar to the 45:55 untreated diet.

This trial was conducted in South Dakota, during one of the region’s coldest winters in recorded history. The milk production response indicated that the enzymes were active under these cold conditions, according to results reported by Schingoethe, Stegeman and Treacher in the Journal of Dairy Science, May 1999 issue.

In the Schingoethe experiment, daily income over feed costs increased 32 to 88 cents US per cow per day. When compared with feeding more concentrate, enzyme treatment changed the estimated daily income over feed cost by minus 25 to plus 31 cents US per cow per day, depending on level of enzyme application.

The enzyme preparation used in this experiment is not commercially available. It shows financial promise if it could be incorporated for a reasonable daily cost.

Getting the Best Bank for Your Enzyme Buck

Considering an enzyme additive in your feeding program? For economic efficiency, Lethbridge researchers recommend that you:

• Use a feed enzyme specifically designed for cattle.
• Use the appropriate dose. Don’t overfeed.
• Apply feed enzymes to the diet in liquid form. They’re sold as powder and liquid but both forms must be mixed with water and applied to feed. Topdressing an enzyme powder onto the ration is not effective.
• Apply enzymes to dry feeds, such as hay or dry grains, for maximum binding with the nutrient substrates.

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