Nutritional Strategies to Mitigate Coccidiosis

Coccidiosis is a disease with substantial economic impact (Muthamilselvan et al., 2016), particularly due to the push to ban anticoccidials. Vaccines are available but can be expensive, and are often implemented for free range and breeder flocks only. Thus, it is imperative to find effective nutritional alternatives to reduce the impact of coccidiosis on broiler chickens. The aim of this experiment was to determine if the nutritional strategies of post-pellet whole wheat (WW), xylooligosaccharide (XOS), high fat (HF, vegetable oil), high carbohydrate (HC), supplementation of threonine and branched-chain amino acids (Thr + BCAA) and short-chain fatty acid (SCFA) inclusions may assist broilers to combat the severity of coccidiosis challenge, in comparison to a ground grain, negative control (unchallenged, NC) and positive control (challenged, PC) diets, containing breed recommended nutrient levels. A total of 648 day-old males from the female Ross 308 parent line (six replicates, 12 birds/pen) were allocated to one of the nine dietary treatments on the basis of initial body weight. Birds were offered starter (d 1 – 10), grower (d 10 – 21) and finisher (d 21 – 35) diets. Birds in the challenge treatments were dosed with E. maxima and E. acervulina (Eimeria Pty.) in 1 ml sterile phosphate-buffered saline (PBS), while un-challenged birds were dosed with 1 ml PBS on d 14. Birds had unlimited access to feed and water in an environmentally controlled facility. Lighting and temperature followed Ross 308 guidelines. Fecal collection was performed daily from d 17 to 28 for coccidial oocyst counts. Feed intake, weight gain and FCR were calculated for each dietary phase. Four birds/pen were sampled on d 21 to assess intestinal lesion scores. The challenge had the greatest impact on performance during the finisher phase, where weight gain of the NC treatment was numerically higher than the PC treatment (1,502 vs 1,421 g; P = 0.129). During this period, the NC treatment tended to have a better FCR than the PC treatment (1.572 vs 1.736; P=0.06). Through this phase, the XOS treatment maintained weight gain (1,422 vs 1,502 g; P > 0.05) and FCR (1.740 vs 1.572; P > 0.05) in comparison to the NC treatment. Over the entire study, the WW and HF treatments had the lowest weight gain (2,236 and 2,252 vs 2,431 g; P < 0.001) and the poorest FCR (1.883 and 1.840 vs 1.510; P < 0.001) compared to the NC treatment. There was no significant effect of the treatments on intestinal lesion score on d 21. Fecal samples on d 21 contained no oocysts in the NC treatment whereas the PC treatment had the highest oocyst counts of E. maxima and E. acervulina (650 and 11,467 vs 0 OPG; P < 0.001). XOS (280 vs 650 OPG; P < 0.001) diets had lower counts of E. maxima oocysts in feces compared to the PC. WW diet significantly reduced E. acervulina oocysts (3,600 vs 11,467 OPG; P < 0.001) in feces compared to the PC diet. No significant difference on mortality was found in between treatments. Overall, XOS and WW diets had potential to reduce the number of E. maxima and E. acervulina oocysts in feces.

ACKNOWLEDGEMENTS: The authors would like to thank Poultry Hub Australia, AB Vista andEimeria Pty. Ltd., Australia, for funding this project. They also would like to acknowledge Greg Underwood, Petrina Young and Michelle Benham of Eimeria Pty. Ltd for their laboratory support.