Date of Award

1984

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Abstract

Laboratory tests were conducted to evaluate four types of mechanical, two types of chemical and combinations of mechanical-chemical conditioning treatments on drying rate and quality of ryegrass forage. Mechanical treatments ranged from cuticle abrasion to crushing of the stems while the chemicals were expected to remove or disrupt epicuticular waxes. The statistical design was a randomized block with two observations per cell. Analysis of variance results yielded highly significant block-treatment interaction for all variables examined. Two types of drying pattern were indicated. For treatments restricted to the plant surface as caused by the brushes and chemicals, the drying pattern was similar to that of the untreated plant which varied with maturity while crushed forage dried more uniformly. Hence crushing and splitting the stems by the intermeshing rubber rolls to disrupt and bypass tissue resistances proved more effective than all other treatments. The drying rate was also doubled. Removing surface wax layer and part of the cuticle caused only moderate increases in drying rate indicating that epicuticular resistance for ryegrass is only a small fraction of the total resistance to moisture loss. The combinations of mechanical-chemical treatments were not more effective than mechanical treatments only. In general, all conditioning treatments affected the stems more than the leaves and the difference in moisture content between leaves and stems was smallest when the stems were split to some degree. Clipping the leaves off the stem severely retarded the drying rate of the stem indicating that the latter loses much of its water through the leaves. Losses resulting from breakage of leaves were generally low for all treatments and averaged less than 3 percent of dry matter. Conditioning systems which split the plant stems also had the most efficient power consumption to drying time reduction conversion ratio. There was little difference in quality among all treatments. Non-linear regression analysis shows that the diffusion equation did not describe the drying data adequately. Instead the data set was divided into parts and an empirical model fitted to each section.

Pages

218

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