The influence of high dietary concentrations of whole wheat and different forms of coccidiosis control on broiler production, nutrient digestibility and on the composition of the intestinal microflora

An experiment was carried out with a total of 2304 broilers over a period of 35 days in a 2 x 3 factorial design. The birds were randomly divided into 6 experimental groups housed in 48 floor pens (8 replicate pens/group), and were fed with whole wheat either in conventional amounts (10-21d, 15%; 22-35 d, 25%) or in high amounts (10-21d, 30%; 22-35d, 50%). Whole wheat was given as supplement to compound pelleted diets, which were adjusted with respect to their wheat content in order to provide the same total dietary wheat concentration. Protection against coccidiosis was either not provided, or was obtained by vaccination (Paracox-5 Vet.), or by dietary addition of salinomycin (Sacox, 60 mg/kg feed). At 35 d, broilers fed with high whole wheat content weighed less (2043g vs 2117 g, P<0. 001) and had a poorer feed utilisation (1.70 vs. 1.66, P<0.01). The water consumption decreased (5508 mL vs. 5701 mL, P<0.03) as compared to birds fed with conventional amounts of whole wheat. The relative gizzard weight increased following intake of high whole wheat concentrations. Until 21 d, the pH of the gizzard contents of birds fed high whole wheat amounts was approximately 0.5 units higher (P<0.001) than of birds fed conventional amounts of whole wheat, which may indicate that the digestive tract of the young bird is not developed sufficiently in order to respond with an increased hydrochloric acid secretion to an increased mechanical stimulation of the gizzard by whole wheat. Dietary inclusion of salinomycin increased body weight in the range of 80g (P<0.01), improved feed conversion ratio (P<0.001), and reduced the counts of lactic acid bacteria and C. perfringens in the digestive tract. Further, dietary salinomycin addition improved AMEn (P=0.07) and apparent digestibilities (total collection week 4-5) of organic matter (P=0.10) and fat (P<0.01). The apparent nitrogen retention was higher in birds fed the low whole wheat level than in birds fed the high whole wheat level (P<0.03). It is concluded, that the use of high whole wheat concentrations (30 % in the early and 50 % in the late grower phase) negatively influences performance results and does not have any beneficial effect on gastrointestinal health. If ionophore coccidiostats like salinomycin are withdrawn as feed additives and substituted by vaccination in the future, significant production losses can be expected. _____________________________________________________________________________