Ruminal digestion kinetics of citrus peel

Three experiments were conducted to investigate digestion kinetics of citrus peel in the rumen of cows fitted with rumen canulae. In the first experiment silage of orange peel was studied, while in the second experiment fresh peels from two lemon varieties were studied in conjunction with orange peel. The third experiment included silage of orange peel and sugar cane prepared in mixture with broiler litter. Corn silage was used as a reference. Treatment samples, dried at 50°C, were placed in heat sealed nylon bags, which were suspended in the rumen for varying times up to 48 h of incubation. A lag phase was observed with orange peel silage, showing residual DM decay commencing at 4 h of incubation. Rates of degradation did not differ significantly between citrus peel, neither between orange peel and orange peelsʹ silage, and averaged 2.9% h−1. Effective degradability was also similar for citrus peel fresh or as silage, ranging from 51% to 58% at an outflow rate of k = 0.05. Addition of calcium hydroxide to peels showed some negative effect on ruminal digestibility, depressing effective degradability by 5 to 10%, but did not affect rates of degradation. For all citrus peels, the constants (a + b) of the non linear regression (NLIN) models by least square summate very near to unity. This shows high potential degradable DM in the rumen, suggesting high energetic value for cattle.