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Rights & Permissions Free Resources Display this book on your site! Related Titles Dietary Reference Intakes for Energy, Carbohydrate, Fiber, Fat, Fatty Acids, Cholesterol, Protein, and Amino Acids (Macronutrients) Dietary Reference Intakes for Water, Potassium, Sodium, Chloride, and Sulfate Other Related Titles Nutrient Requirements of Goats: Angora, Dairy, and Meat Goats in Temperate and Tropical Countries (1981) Board on Agriculture (BOA) Web Search Builder Use this book's key terms to search within this book, across our collection, or across the Web. Skim This Chapter Skim this chapter and use this chapter's key terms to search within this book. Reference Finder Paste in your own text to find books that relate to your topic. Page 13   E-mail  Facebook  Digg  Stumble  Twitter More The following HTML text is provided to enhance online readability. Many aspects of typography translate only awkwardly to HTML. Please use the page image as the authoritative form to ensure accuracy. 4 HERBAGE AND BROWSE UTILIZATION In comparison to other domestic animals, goats have unique preferences for shrubs and tree leaves, whether deciduous or evergreen (Fingerling, 1905, 1907, 1909; Cory, 1927; Edwards, 1948; Wilson, 1957). Compared with cattle or sheep they select from a wider array of plants, particularly woody plants (Fraps and Cory, 1940; Maher, 1945; McMahan, 1964). Their pattern of diet selection compares closely with that of small ruminant game animals (McMahan, 1964; Hoppe et al., 1977). Grasses and herbaceous flowering plants (forbs or weeds) are also commonly selected (Knight, 1965; Malechek and Leinweber, 1972a,b; Tetteh, 1974). Wilson (1957) observed that goats showed a special preference for the influorescences of grasses. Because of their unusual preferences for leaves of woody plants, they have been exploited as weapons against encroaching brush species. Early studies in the deciduous woodlands of the United States observed that goats would effectively clear away understory and would actually kill some trees up to 6 inches in diameter (Woods, 1903). In East African thorn-bush areas, goats controlled sprouts and regrowth following mechanical control (Staples et al., 1942; Oates, 1956). However, goats do not select only invading plants, and care must be taken to avoid the overstocking that can lead to destruction of all ground cover (Hornby and Rensburg, 1948; Wilson et al., 1975). The most successful use of goats in the control of invading plants involves intensive grazing for a short period, followed by removal of all grazing for an extended period to allow for recovery of desirable plants. This method is not, of course, effective when goats find invading plants unpalatable. Provenza (1978) portrayed the goat as a mobile pruning machine that modified bushy shrubs and thereby increased the accessibility of cattle to more nutritious forage. The observation of synergistic effects between animal species has led to widespread acceptance of combination grazing. Talbot and Talbot (1963) recognized the mutual benefit of mixed species grazing by wild ruminants in East African savannas. Mixed grazing has also increased yields of animal products from rangelands in Texas (Merrill, 1975). Goats consume approximately the same weight of forage DM as do sheep of similar size (Geoffroy, 1974). The exact amount that they will voluntarily consume is influenced by several factors. Malechek and Leinweber (1972a,b) suggest that goats will eat more forage if they have access to the more preferred species. Devendra (1975) found that voluntary intake by goats decreased as the forage matured. This effect is overcome partially by chopping and pelleting the forage (Fehr, 1971; Fonolla et al., 1972; Devendra, 1977b). Environmental factors such as temperature and humidity also often affect the level of voluntary intake (Chenost, 1972b). Browse (leaves and twigs of trees and shrubs) and forbs generally contain higher levels of crude protein and phosphorus during the growing season than do grasses (Rector and Huston, 1976). But many palatable browse species are limited in value because of one or more inhibitors that may bind or otherwise prevent utilization of nutrients contained in the plants. These inhibitors include excessive lignification of woody twigs, and tree leaves that physically bind or encapsulate the nutrients (Short and Reagor, 1970; Singh et al., 1972). Essential oils (terpene-based organic compounds) are present at relatively high levels in some range shrubs and apparently inhibit growth of rumen bacteria (Oh et al., 1968). High levels of tannins are found in some of the important browse plants and depress digestion of feedstuffs by binding and/or inhibiting enzymatic activity (McLeod, 1974; Gartner and Hurwood, 1976). Fraps (1924) reports the trace of digestible protein content of live oak leaves was zero. Nastis (1977) found Gambel oak (Quercus gambelii) to be less digestible at a young, tender stage than when mature because of the high tannin concentration in young leaves. Other compounds such as silica may also limit the value of browse materials (Short et al., 1973). Although the reasons are not fully understood, field observations indicate that goats under browse conditions perform better than might be expected from the above cited reports. In spite of concern that browse materials are less nutritious than would be indicated by chemical analysis, there is growing evidence that many, if not most, of the grasses, shrubs, and tree Page 13 Front Matter (R1-R8) 1 Introduction (1-1) 2 Nutrient Requirements (2-9) 3 Table of Nutrient Requirements (10-12) 4 Herbage and Browse Utilization (13-14) 5 Ration Formulation and Examples of Typical Rations (15-20) 6 Nutrition-Related Metabolic Disorders (21-23) 7 Feed Composition Tables (24-72) Bibliography (73-91)

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Nutrient Requirements of Goats: Angora, Dairy, and Meat Goats in Temperate and Tropical Countries 4 HERBAGE AND BROWSE UTILIZATION In comparison to other domestic animals, goats have unique preferences for shrubs and tree leaves, whether deciduous or evergreen (Fingerling, 1905, 1907, 1909; Cory, 1927; Edwards, 1948; Wilson, 1957). Compared with cattle or sheep they select from a wider array of plants, particularly woody plants (Fraps and Cory, 1940; Maher, 1945; McMahan, 1964). Their pattern of diet selection compares closely with that of small ruminant game animals (McMahan, 1964; Hoppe et al., 1977). Grasses and herbaceous flowering plants (forbs or weeds) are also commonly selected (Knight, 1965; Malechek and Leinweber, 1972a,b; Tetteh, 1974). Wilson (1957) observed that goats showed a special preference for the influorescences of grasses. Because of their unusual preferences for leaves of woody plants, they have been exploited as weapons against encroaching brush species. Early studies in the deciduous woodlands of the United States observed that goats would effectively clear away understory and would actually kill some trees up to 6 inches in diameter (Woods, 1903). In East African thorn-bush areas, goats controlled sprouts and regrowth following mechanical control (Staples et al., 1942; Oates, 1956). However, goats do not select only invading plants, and care must be taken to avoid the overstocking that can lead to destruction of all ground cover (Hornby and Rensburg, 1948; Wilson et al., 1975). The most successful use of goats in the control of invading plants involves intensive grazing for a short period, followed by removal of all grazing for an extended period to allow for recovery of desirable plants. This method is not, of course, effective when goats find invading plants unpalatable. Provenza (1978) portrayed the goat as a mobile pruning machine that modified bushy shrubs and thereby increased the accessibility of cattle to more nutritious forage. The observation of synergistic effects between animal species has led to widespread acceptance of combination grazing. Talbot and Talbot (1963) recognized the mutual benefit of mixed species grazing by wild ruminants in East African savannas. Mixed grazing has also increased yields of animal products from rangelands in Texas (Merrill, 1975). Goats consume approximately the same weight of forage DM as do sheep of similar size (Geoffroy, 1974). The exact amount that they will voluntarily consume is influenced by several factors. Malechek and Leinweber (1972a,b) suggest that goats will eat more forage if they have access to the more preferred species. Devendra (1975) found that voluntary intake by goats decreased as the forage matured. This effect is overcome partially by chopping and pelleting the forage (Fehr, 1971; Fonolla et al., 1972; Devendra, 1977b). Environmental factors such as temperature and humidity also often affect the level of voluntary intake (Chenost, 1972b). Browse (leaves and twigs of trees and shrubs) and forbs generally contain higher levels of crude protein and phosphorus during the growing season than do grasses (Rector and Huston, 1976). But many palatable browse species are limited in value because of one or more inhibitors that may bind or otherwise prevent utilization of nutrients contained in the plants. These inhibitors include excessive lignification of woody twigs, and tree leaves that physically bind or encapsulate the nutrients (Short and Reagor, 1970; Singh et al., 1972). Essential oils (terpene-based organic compounds) are present at relatively high levels in some range shrubs and apparently inhibit growth of rumen bacteria (Oh et al., 1968). High levels of tannins are found in some of the important browse plants and depress digestion of feedstuffs by binding and/or inhibiting enzymatic activity (McLeod, 1974; Gartner and Hurwood, 1976). Fraps (1924) reports the trace of digestible protein content of live oak leaves was zero. Nastis (1977) found Gambel oak (Quercus gambelii) to be less digestible at a young, tender stage than when mature because of the high tannin concentration in young leaves. Other compounds such as silica may also limit the value of browse materials (Short et al., 1973). Although the reasons are not fully understood, field observations indicate that goats under browse conditions perform better than might be expected from the above cited reports. In spite of concern that browse materials are less nutritious than would be indicated by chemical analysis, there is growing evidence that many, if not most, of the grasses, shrubs, and tree

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Nutrient Requirements of Goats: Angora, Dairy, and Meat Goats in Temperate and Tropical Countries leaves selected by goats are of high nutritional value (Fraps and Cory, 1940; Bissell and Weir, 1957; Butterworth, 1967; Wilson et al., 1971; Bhandari and Gupta, 1973; Short et al., 1974; Cordova and Wallace, 1975; Rector and Huston, 1976; Wilson, 1977). It has been suggested that browse plants, shrubs, and tree leaves should be given more attention in the feeding management of goats (Sidahmed et al., 1981b). Several reports indicate that goats are more efficient digesters of forage, especially the fiber fraction, than other domestic animals (Ademosun, 1970a,b; Gihad, 1976; Devendra, 1977a,b; Sharma and Rajora, 1977). Huston (1976) reported a lower digestive efficiency for goats than for cattle for several forages. Other workers have shown that goats surpass other ruminants in digesting some forages but not others (Jones et al, 1972; ElHag, 1976). Nonplant factors affecting digestibility of forages by goats include geographical location (Chenost, 1972a), level of forage consumption (Devendra, 1967a,b; Sharma and Murdia, 1974), concentrate supplementation (Castle, 1956a; Chenost, 1972c; Saxena et al., 1972), and rate of passage through the gastrointestinal tract (Castle, 1956b; Short et al., 1965; Ehrlein and Hill, 1970; Hamada, 1973). Because significant differences are usually small, it is suggested at this stage that the digestive efficiencies of sheep and goats be considered comparable. Any differences that appear to exist deserve further studies (Coblentz, 1977; McCammon-Feldman, 1980; Van Soest, 1980; Sidahmed et al., 1981a,b). Campbell et al. (1962) conceded the importance of the brush-eating characteristics of the goat, but emphasized the animal’s importance as a utilizer of forages and a producer of human consumable goods (meat, milk, and fiber). The goat offers an opportunity, sometimes the only alternative, for deriving value from a vast reservoir of natural resources, and unwanted assortments of herbage, shrubs, tree leaves, and plant refuse and by-products.

Representative terms from entire chapter:

invading plants