Effect of high copper dosing on hemicellulose digestibility in cecectomized cockerels.

A precision-fed cockerel digestibility assay using ground corn cobs was conducted to test a theory that birds fed pharmacological doses of Cu (250 mg Cu/kg diet) may exhibit a higher hemicellulose digestibility due to increased release of lysosomal enzymes in the bile. Finely ground corn cobs were crop intubated into adult cockerels that had been pretested on diets containing either 0 or 250 mg Cu/kg (from CUSO4.5H2O). Copper-loaded cockerels showed higher (P < .05) true dry matter digestibility, hemicellulose digestibility, and TMEn than the control cockerels. True dry matter digestibility of corn cobs was 11.1% in Cu-loaded cockerels, which was nearly double that observed (6.2%) in control cockerels. Hemicellulose digestibility also increased from 22.1% in control cockerels to 36.6% in Cu-loaded cockerels. Copper-loaded cockerels obtained some TMEn (117.7 kcal/kg) from corn cobs, whereas the control cockerels obtained no TMEn from the corn cob intubation. The preliminary results presented herein demonstrate that pharmacological doses of dietary Cu may improve hemicellulose digestibility, which may in part explain the growth-promoting effect of Cu.