ABSTRACT
Effects of chemical treatment of cotton byproduct (CBP) on apparent digestibility, mineral balance, urine volume and pH and in vitro digestibility were studied in three experiments with growing lambs and a rumen-fistulated steer. Apparent dry matter digestibility (DMD) and apparent organic matter digestibility (OMD) of total diets were increased (P < .01) by 35.4 and 35.7% in Exp. 1, and by 16.2 and 13.6% in Exp. 3. The CBP was treated wih 4% (4 kg sodium hydroxide/96 kg CBP dry matter) sodium hydroxide (NaOH) and fed at 70% of the total dietary intake. Treatment of CBP with nitric and sulfuric acid increased (P < .01) both DMD and OMD 25% (Exp. 1). In Exp. 2, NaOH treatment decreased (P < .05) organic matter, cellulose and lignin content of CBP and increased (P < .05) ash content. In vitro digestibilities of dry matter, organic matter and cell walls were increased (P < .05) by NaOH treatment. Volume of urine excreted by lambs in Exp. 1 and 3 was increased (P < .05) 53% but urine pH was affected by NaOH treatment. Acid treatment, however, resulted in a decrease (P < .01) in urine pH (9.4 vs 5.3). Feeding NaOH-treated CBP at increasing percentages of the diet increased Na balance and decreased K, Cl and Mg balance. NaOH-treated CBP had no effect on Ca or P balance. These results indicate the NaOH treatment of cotton byproduct increases apparent digestibility and that consumption of the treated product may increase the animal's requirement of K, Cl and Mg. Furthermore, urine volume is increased but urine pH is not affected by NaOH treatment.
