Influence of phenology on chemical composition and in-vivo dry matter degradability of Sporobolus pyramidalis

Research Journal of Agricultural and Environmental Management 10/2012; 1(1).


The main objective of this study was to investigate changes in chemical compositions as well as in-vivo dry matter degradability of Sporobolus pyramidalis with maturity. Samples of Sporobolus pyramidalis were randomly collected in the main grazing areas of the University of Zimbabwe farm at three different growth stages (early -4 weeks, medium -8 weeks and late maturity stage -16 weeks). The samples were air dried and milled through a 2 mm screen using a Hippo mill. The chemical composition of the samples was then determined by the Proximate Analysis system. 2 g of each sample in triplicate were packed in nylon bags of 8 x15cm and pore size 40 to 45µm. The samples were then incubated in two mature Holstein-Friesland steers with a mean weight of 450 kg ± 5 kg and surgically fitted with a rumen cannula of 8,5cm in diameter. The steers were fed on a basal diet of Katambora Rhodes grass (Chloris gayana). Incubation was at time intervals of 0 (control), 6, 12, 24, 48, 72, 96 and 120 h. After incubation, bags were washed under running tap water. The control bags were treated the same way as other incubated bags to determine the zero time loss of DM. The bags were dried in an oven for 48 h at 60°C. DM was significantly higher (P < 0.05) at early growth stages, but there was no significant difference in DM between the medium and late growth stages. EE, Ash, NDF and ADF generally increased significantly (P < 0.05), while CP decreased significantly (P < 0.05) with maturity. Degradability characteristics of the early growth stages was significantly higher (P < 0.05) than the medium and late stages of growth but there was no difference (P > 0.05) in degradability characteristics of the medium and late stages of maturity. Up to 8 weeks of age Sporobolus pyramidalis contains CP that can meet the maintenance requirements of cattle and for small ruminants up to 16 weeks. Its maximum in-vivo degradability is estimated to be at 12 weeks.

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Available from: Tawanda Marandure

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