Shade Intensity Influences the Nutrient Quality and Digestibility of Southern Deer Browse Leaves

Abstract

One deciduous and two broadleaf evergreen species of palatable deer browse were grown under three controlled levels of light reduction: 0, 55, and 92% shade. Determinations of nutrient composition and dry-matter digestibility were conducted on leaf tissues collected 7 months each year for 2 years. Throughout the year crude protein and the cell-wall constituents, acid-detergent fiber and cellulose, increased as shade deepened. Phosphorus and calcium levels, generally highest under deep shade, showed little difference in content between moderate shade or full sunlight. Reduced light did not affect the acid-detergent lignin content in deciduous dogwood leaves, but, in evergreen yaupon and honeysuckle, lignin content was highest in deep shade. Highly digestible cell solubles and apparent digestible energy content declined as shade increased. Dry-matter digestibility also declined as shade deepened, except the dry matter of dogwood leaves, either in full sun or in moderate shade, did not differ in metabolic usefulness. Seasonally, all leaves were most nutritious and digestible during spring refoliation. In winter, abscised and weathered dogwood leaves afforded little food value to deer, but the quality and digestibility of yaupon and honeysuckle leaves remained relatively high during this stress period.