“What the producers need to know is from a cost standpoint – how much we can change the feed efficiency or the birthweight,” said the professor of animal sciences and industry and extension specialist at Kansas State University. “The practical endpoint is it influences the bottom line.” He added that there can be negative side effects, including introducing extra nitrogen into the environment, if a pig’s diet is formulated incorrectly.
His work was recognized at the recent American Society of Animal Science-American Dairy Science Association joint annual meeting, where he was awarded the non-ruminant animal nutrition award by the American Feed Industry Association for his research with swine diet and supplements.
Antibiotic use and replacement
Tokach and his team have been examining the most effective ways to use antibiotics as there likely isn’t going to be one product that completely replaces their use, he told FeedNavigator. When antibiotics are used to treat illness, the group has been trying to determine optimal timelines for the effect on pig health, growth and feed efficiency.
Additionally, he said, when antibiotics are used there can be an increase in drug-resistant bacteria, however levels of those bacteria dwindle when treatment stops.
“Some of them are showing that, after we saw resistance rising with the antibiotic, when we removed it from the diet, the resistant bacteria were (going) down to the baseline at the beginning of the study,” Tokach said.
The work is predominately focused on the use of antibiotics to treat an illness, he added. Only a few trials have been done along that line of questioning.
“We already practice a lot of those withdrawal (periods) with antibiotics already, so they’re not used closely before market,” he said. “When we look at resistance, we have to look at how these are used in the field, and that’s not always done in the experiments.”
Questions of copper, zinc and amino acids
He also has been screening possible antibiotic replacement treatments like additive zinc and copper to see if they promote resistant reactions, as both are often given to young pigs either to control diarrhea or for growth promotion, said Tokach.
Another area of research includes the attempt to determine the most effective levels of synthetic amino acids for use in young pigs, he said.
As amino acids have become available in larger amounts, the question has become to what degree they can replace protein sources, he said. The group has looked at several amino acids including lysine, threonine, methionine and tryptophan, and more recently they’ve examined use of valine and isoleucine.
“In the late finishing period, we know we have some difficulty when we replace too much soybean meal with synthetic amino acids (but) it doesn’t happen earlier in the pig’s life,” said Tokach. “You lose economic benefits pretty quickly, so that’s one of the areas we’re really focusing on.”
Research details
One amino acid study examined the effect of using tryptophan by testing the effects of the standardized ileal digestible (SID) tryptophan: lysine (Trp:Lys) ratio for growth and expense in nursery pig diets, reported researchers.
In the study, 1,088 pigs were given one of seven diets in a randomized complete block design for a period of 21 days. The diets contained 30% dried distiller grains (DDGS) and were 14.5%, 16.5%, 18%, 19.5%, 21%, 22.5% and 24.5% SID Trp:Lys ratio. The ratio was increased by adding L-Trp to the regular diet and replacing corn, and the SID Lys was lower than the estimated requirement to make it the second limiting amino acid.
The work found that increasing the SID Trp:Lys ratio through 21% improved the average daily gain, the average daily feed intake and the final body weight of the pigs. Additionally, the income over feed cost also improved, stated the researchers.
They concluded that designing diets for young pigs with less than 18% SID Trp:Lys reduced growth performance and feed intake.
“Overall, growth and economic variables improved in a quadratic fashion with increasing SID Trp:Lys ratios,” the researchers found. “Although feed cost increased with the increasing Trp:Lys ratio, the increased incremental value of the increased growth negated the increased diet cost.”
What’s next
What works in the lab, does always trigger the same results in when used in the field, said Tokach. So the next step for the work with amino acid levels will be to try them on a larger scale.
Additionally, not much work has been done looking at gestation and amino acid levels, so that may provide an area for future research, he said.
“We just had an experiment out looking at lysine energy requirements and we intend to follow that up looking at the amino acid in different stages of gestation,” he said.
For more information regarding the work that Tokach and members of his research team have been doing visit http://krex.k-state.edu/dspace/.