Dry matter intake, apparent digestibility and excretion of purine derivatives in sheep fed tropical legume hay

Four ruminally cannulated wethers (31 +/- 1.3 kg) were used in an experimen t with a 4 x 4 Latin square design to estimate the DM intake, apparent dige stibility, nitrogen balance, rumen ammonia and microbial protein production . The sheep had ad libitum access to either Cassia rotundifolia (Cassia), L ablab purpureus (Lablab), Macroptilium atropurpureum (Siratro) or Stylosant hes guianensis (Stylo). Dry matter intake of cassia was lower (P < 0.001) t han that of lablab, siratro and style hays. Organic matter intake was great er (P < 0.001) for lablab, siratro and style hays than that of cassia. Dry matter digestibility was higher (P < 0.05) for lablab hay, than that of cas sia, siratro and style hays. The organic matter digestibility ranged from 0 .579 for cassia hay to 0.617 for style hay and there were no differences (P > 0.05) among the legume hays, Nitrogen intake was highest (P < 0.05) in s heep given style hay and least in sheep fed cassia hay. Animals given labla b, siratro and style hays had higher (P < 0.05) faecal and urinary N compar ed to those on cassia hay. Rumen ammonia N concentration was highest (P < 0 .05) in sheep given lablab while sheep offered siratro and style had interm ediate values, and least in animals fed cassia hay. The ammonia levels were above the recommended optimal level of 50 mg N/I. The total purine derivat ive excretion in the urine and microbial N supply was not different (P > 0. 05) among treatments. From the presented findings it is concluded that the intake and digestibility in sheep of the four legume hays are variable and provide adequate rumen ammonia N for maximum rumen microbial growth making then ideal protein supplements to ruminants fed low quality roughages, (C) 2000 Elsevier Science B.V. All rights reserved.