Summer diet of Spanish goats grazing chaparral.

The browsing preference and feed intake of Spanish goats was studied on a 0.2-ha chaparral field in which a wild fire had occurred 5 years earlier. The dominant shrub speices were chamise (A denostomafasciculatum), scrub oak (Quercus dumosa), eastwood manzanita (A rctostaphylos glandulosa), and ceanothus (Ceanothus greggii). Four goats with esophageal fistulae were used to sample the forage. The browsing preference of Spanish goats was highly directed (about 80%) towards scrub oak and chamise. The remainder of the diet was mostly grasses and forbs, while eastwood manzanita and cupleaf ceanothus made a negligible contribution. Shrub preference was not related to availability as manzanita and ceanothus had the highest volume and were the most abundant species. Regression models to estimate IVDMD from the diet's chemical and botanical contents were derived. IVDMD of esophageal samples was positively correlated with the content of grass and forbs and negatively correlated with the sum of the percentages of scrub oak and chamise. Browse intake by grazing ruminants is reported to vary widely with season, alternative vegetation, and type of animal (Wilson 1969). Several studies in the United States (Merrill 1975 and Davis et al. 1974), Australia (Wilson et al. 1975), Africa (Griego and Malechek 1975 and Du Toit 1972), and Malaysia (Davendra 1978) indicate that goats may consume large amounts of browse. Wilson et al. (1975) reported that young feral goats grazing alone had 50% browse in their diets and consumed 70% to 90% browse when they grazed plots following sheep. Malecheck and Leinweber(1972a,b) reported that goats grazing on ranges in the Edwards Plateau of Texas showed a distinct preference for grass from June to October, while browse was an important food item in winter and early spring. They showed that the botanical and chemical composition of the diet of goats was responsive to range condition and to the stocking rate. Similarly, earlier studies by Fraps and Cory (1940) indicated that goats had a greater tendency than cattle or sheep to vary their diet with changing seasons. The ability of goats to utilize browse is probably an important factor contributing to their survival in marginal areas where the feed quality is poor and does not provide minimal nutrition to support cattle and sheep (Davendra 1978, Huston 1978, and Wilson 1969). Comparative studies between angora and Spanish goats by Merrill (1975) and Davis et al. (1974) indicate that Spanish goats eat less grass and forbs than angora goats. Also, Taylor (1975) and Merrill and Taylor (1976) found that Spanish goats are more effective than angora goats as a brush control agent, particularly under poor range conditions. Under more favorable range conditions, angora goats were more efficient. The purpose of this study was to assess summer diet selection and feed intake by Spanish goats browsing chaparral. Regression Authors are research assistant, professor, Department of Animal Science, and associate professor, Department of Botany. Department of Animal Science, University of California, Davis 95616. The assistance of W.L. Graves, Farm Advisor, Cooperative Extension, San Diego County and the Discanso Ranger District of Cleveland National Forest, U.S.F.S. , is greatfully acknowledged. Manuscript received July 23, 1979. coefficients and other statistical parameters relating the dietary chemical and botanical composition (X's) to the in vitro dry matter digestibility (Y) were also computed. Materials and Methods Field-Procedure-Plants The study took place during the summer of 1977 on a 0.2-ha chaparral brush field in the Discanso Ranger District, Cleveland National Forest, San Diego County, in which a wild fire had occurred 5 years earlier. The elevation was approximately 1,200 meters, and the dominant shrub species were chamise (Adenostomafasciculatum), scrub oak (Quercus dumosa), eastwood manzanita (Arctostaphylos glandulosa), and cupleaf ceanothus (Ceanothus greggii). Less than 2 weeks before sampling, an unseasonal early and heavy rain contributed to the growth of herbaceous vegetation (grasses and forbs). Animals Nine 1to 2-year-old (24-38 kg body weight) Spanish goat wethers were used. Permanent esophageal fistulae were established and closed with removable plugs in four goats to collect diet samples (VanDyne and Torell 1964). Fresh cuts of the dominant shrub species were pen fed to the goats for four days before sampling. Goats were confined overnight in a coyote-proof pen (supplied with drinking water and salt) to protect them from predator attack. Our previous work (Sidahmed et al. 1977) indicated that moderate fasting (12 to 24 hr.) did not have a pronounced effect on the composition of samples collected by sheep. Diet samples were collected after a 1 to 2 hour period of grazing each morning, and fecal bags were emptied at 0800 hr daily. After both diet and fecal samples were collected, the animals were left to forage freely until sunset. Diet samples were frozen immediately with dry ice and kept frozen until analyzed. Analytical Procedures Botanical identification (Harker et al. 1964) was performed on all esophageal samples after freeze drying. The freeze-dried samples were spread on an aluminum tray (24 X 15 cm). The fragments occurring under the crosshair of a binocular microscope were identified at 16X magnification where 200 points were selected in an ordered 1cm2 grid. The percentage botanical composition of a species was calculated as: No. of points on a species X100 Total no. of identifiable points Samples were ground in a Wiley Mill (1-mm screen) for proximate analysis and in vitro dry matter digestibility (IVDMD) (Tilley and Terry 1963) using rumen liquor from a goat fed alfalfa hay. The mean daily dry matter intake (g/ W kg3/4) was calculated from the mean daily weight of fecal dry matter output and IVDMD of the esophageal samples. A general multiple regression analysis (GMRA) computer program was used to develop the regression equations (Huszar 1973), JOURNAL OF RANGE MANAGEMENT 34(1), January 1981 33 This content downloaded from 207.46. 13.129 on Mon, 27 Jun 2016 05:35:45 UTC All use subject to http://about.jstor. org/terms 100 U Scrub Oak (Qudm) t Dead (includes high % of live 100