cake for broiler chickens: effects of increasing dietary inclusion on clinical signs of toxicity, feed disappearance, and nutrient digestibility.

The effect of feeding diets with increasing dietary inclusions of cake (CC; 22% ether extract, 34% crude protein) on safety, feed disappearance, and nutrient digestibility was evaluated in a 42-day (d) broiler study. Day-old male chicks (Ross 308; = 744) were divided among 24 test cages in a randomized complete block design with six replicate cages per dietary regimen. Dietary regimens consisted of feeding test diets containing 0, 8, 16, or 24% CC over three growth phases of 2-week duration each. Diets fed from d 14-21 included an indigestible marker. Pen body weight, feed added, and leftover orts for each phase were measured on d 0, 14, 28, and 42 to calculate average daily feed disappearance, average daily weight gain, and gain-to-feed ratio. On d 14, 28, and 42, three broilers per test cage were euthanized by intravenous injection. A gross post mortem examination was conducted and select organs were weighed. Blood was drawn from broilers removed on d 42 to measure serum parameters. Excreta from d 19 to 21 and ileal digesta (10 birds per cage) on d 21 were collected to yield a single pooled sample of each per test cage. Dietary CC inclusion up to 24% did not affect broiler mortality or the incidence of abnormal gross findings. Differences ( 0.05) in serum levels of P, uric acid, T3, and T4 are explained by differential digestible nutrient intake among broilers fed increasing CC inclusion levels. Organ weight as proportion of body weight was not affected by treatment, except for pancreas on d 28 and 42, which both linearly increased ( 0.01) with increasing CC inclusion. Daily feed disappearance did not differ among CC inclusion levels for the overall 42-d study. Increasing dietary CC inclusion level linearly reduced nutrient digestibility of test diets ( 0.01). In conclusion, CC is a safe feedstuff for broilers that can be fed at dietary inclusions up to and including 24% without adverse effects on broiler health.