Evaluation of different types of dietary interventions in a subclinical Eimeria challenge experiment with broiler chickens

Different dietary interventions were tested via feed or water in broilers subjected to a subclinical Eimeria infection. One-day-old male Ross 308 broilers (n = 960) were randomly assigned to one of eight dietary treatments for 35 d, where a four-phase diet program was provided, i.e., starter (d0-9), grower I (d9-19), grower II (19-28), and finisher (d28-35). At 7 days (d) of age, all birds were inoculated with E. acervulina, E. maxima , and E. tenella , except for a Negative Control (NC; TRT8) group. In TRT1-5, the broiler chickens were fed diets supplemented with a variety of compounds in different combinations, i.e., synbiotics, phytobiotics, essential oils, bitter substances, spices, saponins, betaine, thiosulfinates, butyrate, threonine, digestive enzymes, palm kernel fatty acids distillate (PKFAD), or decreased crude protein content in the diet. In TRT1, a combination of synbiotics with phytobiotics was added to the feed and also to the drinking water. The diet for the positive control (PC, TRT6) included Decoquinate as an anticoccidial. The challenged NC (NCchall, TRT7) contained no anticoccidial or test components. From d0-35, body weight gain was similar to the PC group (TRT6) and higher than the NCchall (TRT7) when broiler chickens were fed the TRT2 or TRT4 diets. Only in the PC group (TRT6) a significant decrease in oocyst shedding and lesions scores was detected compared to NCchall (TRT7). This suggests that the dietary interventions tested in this subclinical Eimeria challenge study were not equally effective as anticoccidials but TRT2 and TRT4 may support the broiler chicken during infection.