Nutritive value of diet selected by goats grazing on kermes oak shrublands with different shrub and herbage cover in Northern Greece

Abstract

The nutritional quality of diets of goats grazing in three shrublands (A, B, C) with different cover proportions of shrubby and herbaceous vegetation was studied at monthly intervals 14 times from June 1987 to July 1988 in Northern Greece. The three pasture treatments were: A: 52% shrub vs. 32% herbage, B: 62% shrub vs. 20% herbage, and C: 66% shrub vs. 12% herbage, respectively. Oesophageally fistulated animals were used to collect dietary samples for nutritive evaluation. Crude protein (CP) content, neutral detergent fiber (NDF), lignin and in vitro organic matter digestibility (IVOMD) varied greatly from season to season. The general pattern was similar for the three pastures and independent of shrubby to herbaceous vegetation ratio. Diet quality deteriorated as the amount of herbage available matured and decreased. Goats selected diets higher in CP when grazing in pasture A than in B and C (14.1, 12.1 and 11.4%, respectively; P ≤ 0.05). Dietary levels of CP approached or exceeded maintenance requirements for goats during all grazing periods. Goat diets of pasture A had lower ( P ≤ 0.05) levels of NDF and lignin compared with diets of pastures B and C almost year round. Diets from pasture A tended to be more digestible year round but they had significantly higher levels IVOMD than B and C only in June and July of 1987 and in April of 1988, while IVOMD of diets from B was higher ( P ≤ 0.05) than C in April. It is concluded that shrubby and herbage components, being complementary, were better balanced proportion wise in pasture A.