December 26, 2018
Coccidiosis-based vaccine could impact feed quality, poultry growth, says US researcher
Poultry producers' implementation of antibiotic-free production systems has sparked an increased dependency on vaccination as a way to control coccidiosis, said Samuel J. Rochell, principal investigator of a study conducted by the University of Arkansas' Department of Poultry Science.
However, in the academic article "Optimising Amino Acid Digestibility and Energy Values Used in Feed Formulations for Broilers Vaccinated for the Control of Coccidiosis", he stated that vaccination with live coccidiosis vaccines will instead curtail broiler performance when compared to using "in-feed anticoccidial drugs, presumably due to mild intestinal inflammation and nutrient malabsorption elicited by the cycling of vaccinal oocysts."
"Characterisation of this reduction in nutrient digestibility may allow for the development of targeted nutritional strategies to prevent or minimise performance losses when using coccidiosis vaccines," Rochell explained.
Hence, as part of his research, Rochell aimed to achieve the following objects including: "to compare the effects of coccidiosis control by vaccination and in-feed chemical anticoccidial drug administration on apparent ileal digestibility (AID) of nutrients, ileal digestible energy and intestinal morphology and inflammation in broilers reared to 36 [days] post-hatch; to evaluate the effects of coccidiosis control programmes on AID nutrients and energy for commonly used feed ingredients using the difference method based on basal diets and test diets containing 30% of the test ingredient and 70% of the basal diet; and to determine if live performance and processing characteristics of vaccinated broilers can be improved by feeding diets with additional added soy oil to account for vaccine-induced reductions in lipid and energy digestibility."
Rochell noted that in the first experiment, "it was determined that the most notable impact of coccidiosis vaccination on nutrient digestibility was for lipids, which was reduced by a greater magnitude and at more time points than other dietary components."
In addition, "the timing of the impact of coccidiosis on nutrient digestibility did not completely align with the period in which growth performance was reduced," he added.
It was also "determined that the impact of coccidiosis vaccination on nutrient digestibility varied among both ingredient types and nutrient classes," Rochell pointed out.
But he highlighted that "the additivity in digestibility values among the test ingredients (i.e.; corn, soybean meal and distiller's dried grains with soluble) and basal diets appeared to be inconsistent between control and vaccinated groups, leading to difficulties in estimating the impact on individual feed ingredients."
"Nonetheless, in agreement with initial experiments, AID of lipids was most consistently affected," Rochell said.
Later experiments showed that "increasing the amount of added soy oil in the starter diet did not help birds compensate for a reduction in lipid digestibility experienced during the period of coccidiosis vaccine cycling."
Rather, soy oil in that regard proved to be excessive as it was "actually detrimental to vaccinated birds, as indicated by poorer feed conversion ratios for birds fed the moderate and high energy diets compared to birds fed the starter diet formulated to a standard energy content," Rochell explained.
With the data gathered, he concluded that the use of a live coccidiosis vaccine in broilers leads to a situation in which "lipid digestibility is most impacted."
Rochell added: "Although these experiments were conducted with diets containing a high-quality soy oil, detriments may be even greater for poorer quality supplemental lipid sources. Thus, poultry producers should closely monitor the quality of lipid sources fed to coccidiosis-vaccinated broilers."
In closing, he said that a "relatively lower impact on starch digestibility" presents an indication that "feeding highly digestible carbohydrates may support energy intake in vaccinated broilers with a compromised ability to utilise dietary lipids."
- US Poultry & Egg Association