When feed costs were cheap, you probably thought more about how to get the most milk and less about how efficiently your cows were converting that cheap feed to milk. Now that feed costs are skyrocketing, dairy feed efficiency may well be the key to whether you are profitable or destined to retire prematurely.
Feed additives that improve the efficiency with which dairy cows utilize the nutrients in feed become even more valuable when the cost of feed nutrients rise. For example, let’s say that a microbial additive allows a cow to produce the same amount of milk from a ration that contains 2 pounds less corn.
When corn costs $2 per bushel, the microbial only saves about 7 cents in ration cost and may cost more than the corn it saves. Now that corn is in the $7-per-bushel range, the same microbial saves 25 cents in ration cost and likely provides a positive financial return.
All feed ingredients cost more and may be in limited supply this year, especially grains containing highly digestible starch. Those who cannot find or afford starchy grains often feed alternative byproduct feeds that are quite variable in digestibility.
A feed additive that improves overall digestibility may be able to help byproducts with lower digestibility perform more like highly digestible feeds that were being replaced.
Milk prices are decent right now. The problem is that feed costs are too high to make a profit with current dairy feed efficiencies. It has been suggested that a dairy feed efficiency of greater than 1.5 pounds of energy-corrected or fat-corrected milk (ECM or FCM) per pound of dry matter intake is a good herd benchmark.
Dairy feed efficiency is highest early in lactation and lowest in late lactation. One strategy to maximize efficiency is to maximize early-lactation production. Although not discussed in this article, calving day or routine fresh cow health protocols have been repeatedly shown to improve production during early lactation.
For early-lactation cows, strict ration economics is not the only factor that needs to be taken into account when feeding. Early-lactation dairy cows tend to be in a negative energy status.
That is, because their intake is limited in early lactation, they consume less energy than they require to meet their maintenance needs and produce large amounts of milk. This is occurring at the same time as their metabolic needs are the highest of any stage of lactation.
Maximizing intake during very early lactation is key to achieving efficiency in these cows. Microbial feed additives have been shown to help safely achieve maximum intake.
Early-lactation cows utilize both their fat reserves and muscle tissue to help meet their energy needs but, even so, still fall short of the proper forms of energy. This predisposes them to numerous metabolic issues and subsequently often results in a negative impact on their health, reproductive efficiency and milk production.
One of the problems is that, although fat is the densest form of energy, it cannot be used by all of the body tissues. Energy in the form of glucose is critical in early-lactation cows to meet the specific energy form required to make lactose, which in turn drives milk volume, and fuel the cells that synthesize milk protein.
In addition, glucose supply in the bloodstream is one of the key factors in signaling the cow that it is in favorable energy supply. Energy balance further signals other body systems to begin functioning or reduces key compounds, such as ketones, that inhibit proper function of some body systems.
Recent research suggests that glucose in early lactation becomes even more limiting during heat stress. Remember this article next summer.
So how do we supply more glucose to the bloodstream of early-lactation cows? Unfortunately, you can’t just feed glucose, as the rumen bacteria ferment it into various volatile fatty acids very rapidly and the cow does not get the chance to absorb it directly.
Of all the volatile fatty acids, propionate is the most energy-efficient. Also, fat in the ration (or body fat) cannot be converted to glucose with any efficiency.
Propionate is also the most efficient rumen breakdown compound for making glucose in the cow’s liver. We could add synthetic propionate to the ration, but propionate consumed all at one time overwhelms the absorption pathway, and cows tend to go off-feed.
We can add more grain to the ration to stimulate propionate production by the rumen bacteria, but this is limited because we also get rumen acid overload when grain ferments too rapidly.
Microbial feed additives can help. They tend to increase the total digestion of carbohydrates in the rumen, resulting in more total propionate yield. Some microbial additives will help reduce rumen acid overload, so more grain can safely be fed. This could result in more propionate yield.
The feed additive monensin has been shown to increase feed efficiency by about 2 to 4 percent, mainly by reducing metabolism of methane-producing bacteria. Methane represents lost energy from rumen fermentation. Monensin also tends to inhibit bacteria that produce primarily acetate in the rumen.
This leaves more carbohydrate energy to be converted to propionate, and monensin has been shown to slightly increase the ratio of propionate-to- acetate in the rumen. Unfortunately, inhibition of specific populations of organisms in the rumen may result in conditions that reduce butterfat production in some instances.
A better alternative may be microbial feed additives that stimulate specific populations in the rumen. One bacterial feed additive has been shown in multiple university trials to increase feed efficiency by 4.4 percent to 13.5 percent in mature, early-lactation cows.
Trials also showed that early-lactation cows were in better energy balance when fed this bacterial additive (even while giving more milk than control cows), had fewer metabolic issues and tended to have improved reproductive performance. The primary metabolite of this bacteria is propionate.
A field trial using a microbial feed additive containing the aforementioned bacteria as part of its composition showed mature, early-lactation cows gave the biggest milk response – about 10 pounds more FCM when fed the microbial compared to cows not fed the microbial.
In another field trial, this same additive improved dairy feed efficiency for an entire herd by about 9.5 percent (1.69 vs. 1.54 pounds of energy-corrected milk per pound of dry matter intake) across all stages of lactation. For this herd, economics improved by nearly 65 cents per cow per day when feeding the microbial additive.
With all of this, why don’t nutritionists routinely recommend microbial additives? Some do. But the efficiency effect of an additive does not have a numeric feed value that fits into ration programs. Most of the time we can only measure a feed additive’s benefits after the fact.
For this reason, nutritionists may only routinely recommend additives with a very low cost, such as monensin or yeast culture, because the dairyman risks little if these do not provide better efficiency in a particular ration.
With high feed prices, feed shortages and renewed emphasis on dairy feed efficiency, microbial feed additives may be a valuable tool to evaluate for your dairy. PD
Zimmer is also president of Bio-Vet Inc., based out of Blue Mounds, Wisconsin.
References omitted due to space but are available upon request. Click here to email an editor.
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Bill Zimmer
- Veterinarian
- Bio-Vet Inc.
- Email Bill Zimmer
