One CAI research initiative is focusing on cell wall digestibility through lignin reduction, and another is improving efficiency of protein utilization using genetic engineering to develop “tannin alfalfa.”

USDFRC estimates that a 10 percent increase in fiber digestibility could result in $200 million in annual increase in milk and beef production in the U.S., and a 200 million ton annual decrease in production of manure solids.

Lignin is indigestible.Genetic engineering has been used to “knock-out” genes coding for one or more of the several enzymes the plants use to make lignin and thus make the alfalfa more digestible. This would not only improve alfalfa digestibility, but would give growers more harvest flexibility. As alfalfa matures, the crop's lignin levels also rise. Low lignin alfalfa would allow a later harvest and higher tonnage.

Brown midrib corn is an example of a natural mutation that caused a “knock-out” of one of the lignin biosynthetic enzymes.

The alfalfa with reduced lignin is going through the USDA approval process, and McCaslin expects it to be deregulated next year when breeder seed will be released.

McCaslin said this technology has provided a 24 percent increase in digestibility of alfalfa. This is compared to just a 2 percent improvement in digestibility after 30 years of traditional breeding, he explained.

The second genetic improvement involves increased protein efficiency.

Although alfalfa has a high protein content, protein is rapidly degraded in the rumen, and inefficiently utilized by dairy cows. As a result even high alfalfa diets often require protein supplements when fed to high producing dairy cows.

Inefficient utilization of alfalfa protein also results in increased losses of nitrogen to the environment, potentially affecting water quality. In making alfalfa haylage there is also an extended period of time for post-harvest protein breakdown, often resulting in high nonprotein nitrogen (NPN) content of typical alfalfa haylage. This significantly further decreases efficiency of protein utilization, compared to alfalfa hay.

The USDFRC has identified a gene in red clover (PPO) that is responsible for a compound that significantly reduces post-harvest protein degradation. This gene has now been expressed in transgenic “PPO alfalfa.”

Tannins are found in many plants. They generally bind with proteins, decreasing rate and extent of protein degradation.