title: Dry matter intake, apparent digestibility and excretion of purine derivatives in sheep fed tropical legume hay.
abstract: Four ruminally cannulated wethers (31+/-1.3kg) were used in an experiment with a 4x4 Latin square design to estimate the DM intake, apparent digestibility, nitrogen balance, rumen ammonia and microbial protein production. The sheep had ad libitum access to either Cassia rotundifolia (Cassia), Lablab purpureus (Lablab), Macroptilium atropurpureum (Siratro) or Stylosanthes guianensis (Stylo). Dry matter intake of cassia was lower (P<0.001) than that of lablab, siratro and stylo hays. Organic matter intake was greater (P<0.001) for lablab, siratro and stylo hays than that of cassia. Dry matter digestibility was higher (P<0.05) for lablab hay, than that of cassia, siratro and stylo hays. The organic matter digestibility ranged from 0.579 for cassia hay to 0.617 for stylo hay and there were no differences (P0.05) among the legume hays. Nitrogen intake was highest (P<0.05) in sheep given stylo hay and least in sheep fed cassia hay. Animals given lablab, siratro and stylo hays had higher (P<0.05) faecal and urinary N compared to those on cassia hay. Rumen ammonia N concentration was highest (P<0.05) in sheep given lablab while sheep offered siratro and stylo had intermediate values, and least in animals fed cassia hay. The ammonia levels were above the recommended optimal level of 50mg N/l. The total purine derivative excretion in the urine and microbial N supply was not different (P0.05) 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.
authors.affiliation: Department of Agritex, Ministry of Agriculture, P.O. Box CY 639, Causeway, Harare, Zimbabwe
authors.initials: JF
authors.lastname: Mupangwa
authors.initials: NT
authors.lastname: Ngongoni
authors.initials: JH
authors.lastname: Topps
authors.initials: T
authors.lastname: Acamovic
authors.initials: H
authors.lastname: Hamudikuwanda
authors.initials: LR
authors.lastname: Ndlovu