Editor's note: This is the first in a two-part series on fish meal.

Kevin Jones wouldn't put an ingredient into his clients' rations if it didn't yield a return on their investment. That's one reason why Jones, an independent nutrition consultant from Tulsa, Okla., adds fish meal to some lactating-cow rations.

Fish meal - a source of rumen-undegradable or bypass protein - has improved reproductive performance and increased milk protein content from 3.0 percent to 3.2 percent on many of his clients' farms.

"I've put enough dairies on it and seen the same (response) that I feel comfortable saying that it's true," Jones says.

Several research studies back up what Jones has seen on farm - fish meal boosts reproduction and milk protein. However, fish meal remains an underutilized source of bypass protein, largely because it looks more expensive than other ingredients at first glance or it's not as easy to access as other bypass protein sources.

Take a second look at fish meal. You might find that the benefits outweigh the concerns.

1. It's a good source of bypass protein.
Feeds that contain rumen-undegradable or bypass protein help supplement the microbial protein produced in the rumen. That's why nutritionists sometimes add bypass protein sources such as roasted or extruded soybeans, corn gluten meal or brewers' grains to lactating-cow diets.

Fish meal's bypass protein profile makes it an ideal candidate in rations that benefit from this type of supplemental protein.

According to research, at least 55 percent - and perhaps as much as 75 percent - of the protein in fish meal escapes breakdown in the rumen, says Dave Schingoethe, dairy nutritionist at South Dakota State University.

Fish meal also does an "excellent job at providing an amino acid profile that the cow needs," says John Shirley, dairy scientist at Kansas State University. "If you look at the amino acid profile of fish meal, it is extremely complementary to soy-based products," he says.

That's because soy-based products contain limited amounts of methionine. Fish meal, however, provides a good supply of this essential amino acid. It also is rich in lysine - an essential amino acid that is less available or "limiting" in corn-based products, Schingoethe says.

2. Improves fertility.
Several studies show fish meal enhances conception rates and pregnancy rates.

One such study, published in the October 1994 Journal of Dairy Science, shows fish meal improved conception rates by about 21 percent compared to cows fed no fish meal.

Other research, published in the December 1997 Journal of Dairy Science, found that fish meal improved pregnancy rates by almost 10 percent in a commercial herd in Florida.

During the study, researchers fed fish meal - at the rate of 1.54 pounds per cow per day, or 2.7 percent of diet dry matter - to 154 lactating cows. Control cows in the same herd ate a diet containing

3.2 percent blood meal, meat and bone meal and corn gluten meal, on a dry matter basis. (At the time of this study, it was still legal to feed meat and bone meal.)

According to the results, cows fed fish meal achieved a pregnancy rate of 41 percent, compared to 32 percent for control cows.

In another Florida herd involved in the same study, pregnancy rates were similar between cows fed fish meal and cows fed blood meal and meat and bone meal.

Researchers are not entirely sure how fish meal influences reproduction. However, it may have something to do with certain fatty acids found in fish meal.

"The unique long-chain fatty acids found in fish are thought to be largely resistant to (rumen) microbial changes," says Charlie Staples, dairy nutritionist at the University of Florida. "Therefore, they should pass through the rumen with modest changes and be absorbed from the small intestine and stored in uterine tissues to potentially play a positive role at the time of conception," he adds. (Please see, "How fish meal improves fertility" on page 48.)

3. Enhances milk protein.
Perhaps the most compelling benefit of feeding fish meal is its ability to boost milk protein content - good news for producers paid on components.

According to research from South Dakota State University, published in the May 2001 Journal of Dairy Science, milk protein content increased as the level of fish meal increased in the diet. When fish meal replaced 50 percent of soybean meal in the diet, milk protein percent increased to 3.31, compared to 3.23 percent for cows fed soybean meal.

On-farm results also show a trend toward higher milk protein. Jones, for example, has seen the protein levels in his clients' herds increase from 3.0 percent to 3.2 percent protein when fish meal entered the diet.

Unfortunately, the impact of fish meal on milk production is not nearly as consistent. The University of Florida research shows cows fed fish meal produced about 5 pounds more milk than cows fed blood, meat and bone and corn gluten meals.

Other studies, however, have found fish meal has little influence on milk production.

Despite the inconsistencies in milk production, fish meal doesn't seem to hurt milk fat content. That is, unless you feed too much - more than 1.5 pounds per cow per day.

The South Dakota State research described previously found that feeding fish meal as the only source of supplemental protein depressed milk fat percentage. Cows fed fish meal as the only source of supplemental protein produced 2.87 percent milk fat, compared to 3.04 for cows fed 50 percent fish meal and 50 percent soybean meal.

4. Cost-effective for high producers.
Fish meal runs about $500 to $550 per ton, including freight - several hundred dollars more than other common bypass protein sources. However, when used appropriately, producers with high-producing cows - particularly cows producing at least 75 to 80 pounds of milk per day - will see a return on their investment.

The Kansas State dairy, for example, has seen good results when feeding fish meal. "We see a response when we put fish meal in and when we take blood meal (another bypass protein source) out," Shirley says.

Jones also has seen cows respond favorably to fish meal - most notably by increasing milk protein. "I've also seen a milk response, especially in early lactation," he adds. In one of his clients' herds, for example, milk yield increased 4 pounds per cow per day.

However, the boost in milk protein is perhaps the best incentive to use fish meal, particularly for dairies paid on cheese yield. "By increasing the cheese yield of the milk, they get paid a higher price," Jones says.

Say, for example, the addition of fish meal causes a cow producing 80 pounds of milk per day to yield 0.2 pounds more protein and 3 pounds more milk. If your milk processor values milk protein at $2 per pound, the extra 0.2 pounds of protein is worth 40 cents per day. At a milk price of $12 per hundredweight, or 12 cents per pound, the extra 3 pounds of milk is worth 36 cents per day. Together, these two figures yield an extra 76 cents per cow per day. If fish meal is valued at 25 cents per pound ($500 per ton of fish meal divided by 2,000 pounds in 1 ton equals 25 cents per pound), increased income over the cost of the fish meal is 51 cents per cow per day.

As with any undegradable protein source, be sure to pencil it out, Shirley cautions. "If you are using an undegradable protein source and not seeing results, then it's not worth it," he says.

A future niche market

Besides its reproductive and production benefits, fish meal has been shown to boost levels of conjugated linoleic acid (CLA) - a fatty acid highly regarded for its anti-cancer qualities.

Research in the August 2001 Journal of Dairy Science shows fish meal nearly doubled the amount of conjugated linoleic acid (CLA) in milk fat, explains Dave Schingoethe, dairy nutritionist at South Dakota State University. The greatest response occurred when fish meal totally replaced soybean meal in the diet.

More work is needed to determine a combination that maximizes milk protein content, milk production and CLA levels, yet minimizes milk fat depression - a drawback of feeding too much fish meal.

How fish meal improves fertility

Fish meal contains fatty acids that resist breakdown in the rumen. Researchers believe these fatty acids may be responsible for improving pregnancy rates. Here's how:

1. Fish meal contains fatty acids called polyunsaturated fatty acids.

2. Unique fatty acids within this group largely resist breakdown in the rumen and travel to the small intestine where they are absorbed.

3. Once absorbed, these fatty acids reduce the release of prostaglandin (PGF) from the uterus.

4. This allows the corpus luteum on the ovary to survive and produce progesterone (P) -the hormone responsible for maintaining a pregnancy.