K-State researchers have verified guidelines for histidine, an essential amino acid

Kansas State University researchers are reporting another breakthrough in their work to formulate lower-cost pig diets, a finding they say will help to keep the pork industry profitable and competitive in foreign markets.


Mike Tokach, University Distinguished Professor in the department of animal sciences and industry, said the university’s applied swine nutrition team has determined the nursery-pig requirements for the amino acid histidine.


Swine nutritionists now have more information at their disposal to formulate foods that help pigs grow safely, saves money for producers, and reduces the amount of nitrogen excreted to the environment.


“For a pork producer, what it means is that the nutritionist for the feed company they’re working with can formulate the diets with more feed-grade amino acids, which allows them to lower their costs and use less of the expensive protein sources,” Tokach said.


In recent years, nutritionists have been substituting feed-grade amino acids in pigs’ diets for expensive protein sources, such as soy meal, fish meal and others. The amino acids commonly used in diet formulations for pigs are lysine, threonine, tryptophan, methionine and valine.


Amino acids are the building blocks of protein, and they are naturally available in many of the foods humans and animals eat. In order to grow well and be healthy, pigs need amino acids in the right combination.


That’s why K-State’s swine nutrition group has been working to develop guidelines for adding amino acids in the proportions that are most beneficial for the pig.


In two recent studies, they formulated diets for more than 700 nursery pigs to determine the appropriate level of histidine that could be added to the diet. Researchers believe histidine may be a limiting amino acid, or one that is in insufficient amounts in a food.
K-State doctoral student Henrique Cemin did much of the work to determine what ratio of histidine to lysine would work best to lower costs and still meets the pigs’ protein needs. Lysine is a common amino acid used in diets of nursery pigs, or newly weaned pigs.


“We found that the requirement would range between 29 to 30 percent of lysine,” Cemin said. “In the second trial, we formulated diets that were more around the level of 30 percent (histidine) so that we could have a more precise estimate of the requirement, which happened to be 31 percent of lysine.”


In 2012, the National Research Council, in a publication titled Nutrient Requirements of Swine, reported that the requirement for histidine was 34 percent of lysine. In other words, for histidine to be effective in meeting the amino acid requirements of the nursery pig, it should be added at a level of 34 percent in relation to lysine.
K-State’s findings show that number can be much lower in order to promote feed intake and gain in nursery pigs.


“When you’re talking about using 31 percent, or 33 or 34 percent, it makes an enormous impact on how much of the other synthetic amino acids you can add before histidine becomes limiting,” Tokach said.


He added that much of the information that K-State has learned is probably of most interest to nutritionists who put together the diets. But producers and consumers can benefit from knowing that there are many involved in keeping pork products safe and less expensive at the grocery store.


“Lowering costs is what the ultimate goal is for the producer, and to make sure that when we do formulate the diets that we don’t hurt performance of the pigs,” Tokach said.


K-State has previously done similar work with another limiting amino acid, isoleucine, which will soon be the newest feed-grade amino acid available to producers.


Breakthrough will help lower cost of pig diets