Coccidiosis vaccination impedes nutrient digestibility

Poultry veterinarians and production managers are all too familiar with coccidiosis and its impact on gut health, nutrient absorption, feed conversion and growth rate.

What hasn’t been fully understood is the impact of coccidiosis vaccination, which introduces a controlled dose of live coccidial organisms to day-old birds to stimulate natural immunity — a process that can create subclinical infections that decrease bird performance in early growth stages.

Alyson Gautier, a senior graduate assistant at the University of Arkansas who recently studied the impact of coccidiosis vaccination, has found the vaccine impacts early bird-growth performance as well as nutrient digestibility.

Recovery generally occurs around day 20. But when birds are marketed at 42 to 56 days, that early setback can be significant, she told Poultry Health Today. Birds either don’t recover the lost weight gain or their feed-conversion ratio is poor.

Gautier conducted two experiments to determine the impact of coccidiosis vaccination on the apparent ileal digestibility of nutrients and energy of commonly used feed ingredients in broilers.

Experimental diets consisted of a basal diet and three test diets in which 30% of the basal diet was replaced with either corn, soybean meal or distillers dried grains with solubles (DDGS) to allow for nutrient digestibility of individual ingredients by difference. The ingredients were added at a high inclusion rate to study the main effect of each ingredient, she said.

Results were revealing

“The data demonstrated the impact of coccidiosis vaccination on nutrient and energy digestibility varies among ingredients. However, fat digestibility was most consistently impacted, with the greatest reduction observed for corn,” the study abstract stated.

“Birds with the DDGS diets tended to have an overall improvement in nitrogen and most of the digestibility values,” Gautier said. “Maybe fiber serves as an intestinal health benefit, possibly increasing intestinal turnover and [allowing] the birds to recover faster, but that’s something we need to further evaluate.”

The results were surprising, Gautier said. However, she reiterated the high inclusion rate of the test ingredients (30% of the diet), which is unrealistic compared to typical rations. The next step would be to study more practical inclusion levels.

Typically, the inclusion rate for DDGS would be 3% to 4%, but Gautier hasn’t identified a downside to feeding higher levels of DDGS. However, her initial conclusion might change with follow-up research.