| Serge Y. Landau, Avi Perevolotsky, Dorit Kababya, Nissim Silanikove, Ronit Nitzan, Hagit Baram, and Frederick D. Provenza |
| Authors Landau and Perevolotsky are Range Scientists, Nitzan is Agricultural Research Technician, and Baram is Computer Programmer, Department of Natural Resources, Institute of Field and Garden Crops, Agricultural Research Organization, The Volcani Center, P.O. Box 6, Bet Dagan 50250, Israel; Kababya is Field Advisor, Sheep and Goats Department, Extension Service, Ministry of Agriculture, P.O. Box 28, Bet Dagan 50250, Israel; Silanikove is Animal Scientist, Institute of Animal Science, Agricultural Research Organization, The Volcani Center, P.O. Box 6, Bet Dagan 50250, Israel; Provenza is Professor, Department of Rangeland Resources, Utah State University, Logan, Utah, USA 84322-2810. Corresponding author: Dr. S. Landau; fax: 972 3 9669642; E-mail: vclandau@agri.gov.il |
Abstract |
| High concentrations of condensed tannins in browse impair brush clearing by goats. We studied the effect of polyethylene glycol (PEG, MW 4000), a polymer that binds condensed tannins, on the feeding behavior of Damascus goats (Capra hircas) on a range dominated by tannin-rich lentisk (Pistacia lentiscus L.). This was done with or without a nutritious alternative to browse (alfalfa hay) available at pasture. In phase 1, no hay was provided to goats; in phase 2, hay was distributed daily in the field. In both phases, 6 goats had free access to PEG while at pasture, while 6 goats that grazed separately on another paddock did not. All goats received each night an allowance of concentrate (400 g day-1 of 40% ground corn grain, 40% ground barley, 17% soybean meal and 3% of a mineral-vitamin premix, and contained as fed 16% crude protein (CP) and 2.66 Mcal kg-1 of Metabolizable Energy). The 2 groups of goats alternated daily between paddocks. Goats supplemented with PEG spent more time browsing lentisk than goats in the control group (73 and 41%, respectively, P < 0.0001). Goats in the control group spent more time foraging on dry grasses than their PEG-fed counterparts (28 and 12%, respectively, P < 0.0001). Goats from the PEG group gained body weight at a higher rate than controls. The daily intake of PEG was 450 g, with an intake rate of 1.2 g sec-1. Supplemental alfalfa hay substituted partly for dry grasses in goats' diets, but did not modify the percent of time goats in either treatment spent browsing lentisk. Our data suggest that PEG has the potential to increase intake of tannin-rich species, even where alternative fodder of better nutritional quality is present. However, self-feeding of PEG may not be the best way to provide PEG because goats may ingest more PEG than needed to annul the aversive effects of tannins on food intake. |
| Key Words: Mediterranean browse; self-regulation; nutrition |