Seasonal diet composition and forage selectivity of Boer goats in a semi-arid gypsophilous grassland

Abstract

Botanical and chemical compositions of Boer goat diets, determined with repeated collection of forage samples taken from the goat’s mouth, were studied in a gypsophilous grassland during four seasons of the year. Ten pluriparous goats were used to collect selected forage species. Shrubs were a minor dietary component throughout the year (<7.5%). Goats selected more (p < 0.01) grass during autumn and winter (34.2–37.8%) than during spring (21.2%) and summer (29.0%). During all seasons goat diets were dominated by forbs (>59%). Diets were lowest (p < 0.05) in percentage of crude protein during spring, summer and autumn (13.2 ± 3.5, 13.2 ± 2.4 and 14.2 ± 3.9, respectively) than winter (17.5 ± 2.9) with levels above the recommended quantities for goats throughout the year. In vitro dry matter digestibility of forages selected by goats did not differ between seasons (range 47.4–53.3%). It was concluded that in this particular ecosystem goats preferred forb species over grasses across all seasons. In addition, goats maintained relatively stable diet quality by forage-class mixing of diets.

Keywords: dry matter digestibility, food preferences, grazing, nutrient content, tannins