• A modified faecal harness for grazing goats on Mediterranean shrublands

      Yiakoulaki, M. D.; Nastis, A. S. (Society for Range Management, 1998-09-01)
      A modified faecal harness for goats was specially designed for grazing conditions in dense mediterranean shrublands and subsequently tested successfully for total faecal collection. The details of design and collection are presented.
    • Diets of goats grazing oak shrubland of varying cover in northern Greece

      Papachristou, T. G.; Nastis, A. S. (Society for Range Management, 1993-05-01)
      The effects of 3 brush cover proportions (Low Brush pasture: 52% brush/32% herbage, Medium Brush pasture: 62% brush/20% herbage, and High Brush pasture: 66% brush/12% herbage) on dietary selection of goats in northern Greece were investigated. Diet samples were collected from esophageally fistulated goats during 14 grazing periods at monthly intervals from June 1987 to July 1988. Kermes oak foliage (Quercus coccifera L.) was the main component of the available forage in all pastures during all grazing periods. The herbaceous component contributed more than 50% for the goats' diet during spring for Low Brush pasture, 46% for Medium Brush pasture, and 40% for High Brush pasture. In the remaining grazing periods, goats selected larger quantities of browse. For Low Brush pasture browse contribution ranged from 48% to 66%, for Medium Brush from 54% to 77%, and for High Brush from 66% to 80%. Leaves of all forage species contributed more than 56% during all test periods. The quantities of twigs from shrubs and stems from herbaceous species were low but constant during all test periods. Fruits and flowers, despite representing low percentages of the overall production, were important for the animals' nutrition, since they provided a high percentage of nutrients. Our results indicated that goats adapted diets to forage class availability.
    • Effects of Forage Availability on Grazing Behavior of Heifers

      Scarnecchia, D. L.; Nastis, A. S.; Malechek, J. C. (Society for Range Management, 1985-03-01)
      Effects of decreasing availability of crested wheatgrass (Agropyron desertorum and Agropyron cristatum) on grazing time and biting rate of Angus heifers were investigated. In the first year of the study, as standing crop decreased from 474 to 170 kg dry matter/ha, grazing time increased from 517 to 203 min/day, while biting rate increased from 56 to 64 bites/min. In the second year, as standing crop decreased from 919 to 144 kg dry matter/ha, grazing time increased from 380 to 656 min/day while biting rate increased from 37 to 50 bites/min. Grazing times were similar to those reported in the literature for pastures having much higher levels of available forage. Although grazing times may be correlated with available forage, comparison of grazing times under different pasture conditions are not meaningful unless considered along with other forage and animal factors. On crested wheatgrass pastures, maximum biting rates occurred at lower levels of available forage than reported on tropical pastures.
    • Estimating digestibility of oak browse diets for goats by in vitro techniques

      Nastis, A. S.; Malechek, J. C. (Society for Range Management, 1988-05-01)
      Predicting digestibility of shrubs is important to evaluating many of the world's rangelands. We examined laboratory procedures for predicting in vivo digestion of browse-alfalfa (Medicago sativa) mixed diets and how drying temperature and inoculum source affect digestibility. In addition, we considered the effect of oak tannin on pepsin activity and dry matter digestion. The commonly used Tilley and Terry (1963) two-stage in vitro digestion technique was a precise (r2=0.97) but inaccurate predictor of in vivo apparent digestibility of mixed oak (Quercus gambelii) and alfalfa diets for goats. The Van Soest et al. (1966) neutral detergent method for predicting true digestibility was less precise (r2=0.76). Estimates from the Goering and Van Soest (1970) summative equation were not correlated (P is lesser than or equal to 0.05) with in vivo digestion. Separate regression equations are necessary if in vitro methods are to predict accurately in vivo digestibility of browse diets. In vitro digestibility was inversely related to percentage of oak in the diets and the amount of oak in the inoculum donors' diets. High drying temperatures depressed digestibility of oak browse and this effect was greater for immature than for mature forage.