In: Proceedings of the Southeast Regional Meat Goat Production Symposium "Meat Goat Production in the Southeast - Today and Tomorrow". February 21-24, 1996. Florida A&M University, Tallahassee.
Goats have been successfully used for the biological control of abandoned farmland pastures invaded by herbaceous weeds, vines, multiflora rose bushes and hardwood saplings. Managed defoliation with goats results in a substantial increase in vegetative cover by favorable grass and legume species while reducing or eliminating unwanted shrub species. Old pastures containing multiflora rose bushes and many other weeds grazed with goats and cattle became dominated with grass and clover after four years of grazing. Goats clear brush more effectively and rapidly than sheep. The role of goats as biological control agents will become increasingly important in the future due to environmental concerns and elevated costs of other control methods such as mechanical cutting and herbicide application. In understory woodlots, vines are a significant portion of the diet selected by goats throughout the browsing season; in drier weather diets become more diverse and with the increasing severity of winter acorns, dead leaves and pine needles are consumed. Grazing studies pertinent to the conditions found in the Southeast indicate that Alpine, Angora and Nubian kids grazed on winter wheat gained more than animals grazed on dormant bermudagrass and receiving a daily 24% CP supplement. Angora yearlings grazing sainfoin gained weight faster than those grazed on alfalfa. In addition, does and kids continuously or rotationally grazed on aeschynomene americana gained more weight than those grazed on a bermudagrass/yellow foxtail/dallisgrass mixed pasture. Limit-grazing pregnant Angora does only 2 h a day on winter wheat and ryegrass as an alternative to feeding a concentrate supplement proved to be a viable strategy to maintain animal weight while reducing bermudagrass hay and supplement needs. Stall-feeding studies have shown that tree legumes such as Gliricidia sepium and Leucaena leucocephala can be used to replace some of the concentrate used in kinggrass-based diets for growing male kids and lactating does. Young Toggenburg wethers were unable to meet their nutritional requirements when fed 6 and 9 wk old tall fescue and 7 and 12 wk old Coastal bermudagrass hays. Six months old Stiffleg and Stiffleg X local brush goats grew rather slowly and had a poor feed conversion when fed hay (14% CP) and a 16% CP supplement. With the introduction of the Boer breed and the upgrading of meat-type goats with Boer genetics, research focusing on forage evaluation, byproduct utilization, feeding strategies and the development of economical grazing systems is urgently needed to meet the needs of this emerging industry.
Key Words: Goats, Browse, Forage, Grazing, Biological Control
In the Southeastern United States, goats are becoming increasingly important contributors to the income of many producers. However, little research data are available from our region specifically directed toward feeding programs for goats reared for meat production. The purpose of this paper is to describe research results with potential for the development of practical feeding systems for meat goats.
Much of hill land pasture in the Appalachian region is brush infested. Low cost and low input reclamation procedures are needed to provide owners with ways to maintain theses pastures in production. In a demonstration conducted in the Mountains of western North Carolina, brush goats were grazed alone (30 mature does/ha) or with cattle (17 mature does/ha with 2 to 3, 225 kg steer/ha) for 4 yr in an abandoned apple orchard. Grazing occurred for 45 to 60 d from May to July and for another 24 to 35 d in September and October. The botanical composition of the grazing site was primarily herbaceous weeds such as brambles (Rubus spp.), honeysuckle (Lonicera japonica), chickweed (Stellaria spp. L.), mustard (Brassica spp.), wild strawberry (Duchesna spp.), thistle (Cirsium sp.), multiflora rose (Rosa multiflora Thunb.) and hardwood saplings with some grasses and clover. Over the first three grazing seasons, ground cover in the goat pasture (Table 1) remained at 63 to 68% (T. Harvey, unpublished). However, the cover from favorable grasses and legumes increased from 16% in May 1991 to 52% in October 1993. Ground cover in the control plot declined from 70% in May 1991 to 32% in October 1993, with less than 10% of the cover from grasses. The shift in botanical composition in the grazed plots was attributed to the preference of goats for the broadleaf species, which allowed the grasses to be more competitive. Goats and goats/cattle also were very effective in controlling multiflora roses. Individual multiflora rose bushes were identified and marked to determine the effects of browsing on plant survival. Multiflora rose bushes (Table 2) were practically eliminated after four grazing seasons (T. E. Harvey, unpublished). The reduced height, area, leaf out and density of the bushes indicated that their condition was severely affected by the goats. In addition, 92 to 100% of the rose canes were dead by October 1994. Defoliating multiflora rose bushes at four and eight week intervals starting in May resulted in a 21% plant death at the beginning of the second year, 78% by the third year and 94% by the beginning of the fourth season (Bryan, personal communication). Spring and summer proved to be critical grazing times whereas grazing after August 1 was of negligible value.
Grazing on a powerline right of way for five years in West Virginia, goats reduced brush cover from 45% to 15% in one year whereas sheep took three years to achieve the same results (Magadlela et al., 1995). After five years of grazing, goats had reduced brush cover to 2%. Animal effectiveness, primarily that of sheep, was increased by cutting and herbicide application, but costs were also increased. Goats alone were the least expensive method for clearing brush at $33 ha-1 whereas herbicide application followed by goats or sheep, at $593 ha-1, was the most expensive method (Table 3). Grazing management involving brush defoliation early in the spring and repeatedly during the growing season was very effective. On the other hand, complete defoliation starting in August/September had no significant impact on the woody vegetation and regrowth was 100% the following spring.
In West Virginia, goats grazing improved pasture, unimproved pasture, unimproved pasture with low scrub or high scrub (Table 4) consumed much larger proportions of browse than sheep on the scrub-infested pastures (Prigge et al., 1985). However, little difference in the nutritive value of ingesta selected by goats and sheep was evident within pasture type (Table 5). Arbogast et al. (1990) reported that when stocked at 20 animals/ha on similar West Virginia scrubland, the quality of goat and sheep diets differed little, with the exception of in vitro DM disappearance (IVDMD) values, and appeared to be adequate for maintenance of adult animals (Table 6). Goats selected diets lower in IVDMD during the fall than during the spring (57.3 vs 62.4%, P < .01). Dry matter intakes were similar for both animal species. Sheep showed a tendency to lose more weight than goats but had a greater number of grazing days (P < .01) than the latter. Mills and Bryan (1983) observed that goats, grazed on similar scrub plots as reported by Prigge et al. (1985) and Arbogast et al. (1990), preferentially selected browse and grazed grasses only when browse was limiting. On the other hand, sheep consumed browse only when grasses became limiting. Finally, on the pastures that did not contain browse, grass was the feed of choice for both animal species.
MIXED HARDWOODS FOREST
Goats show great potential as biological agents to control the understory in hardwood forests because of environmental concerns associated with the use of herbicides. and the ban on 2,4,5,T as a management tool. Analyses of diets selected by dairy and meat-type buck kids rotated among four paddocks of upland hardwood forest from July to December were conducted in Arkansas (Hansen et al., 1980, Child et al., 1985). During July and August, more than 65% of the diets selected by the goats (Table 7) were made of vines, primarily honeysuckle, greenbriar (Smilax sp.) and rattan vine (Berchemia scandens) . Vines remained a significant portion of the diets throughout the study period. As vines became less available, the proportion of other browse and conifers increased in the diet. Forbs disappeared from the diet after 3 mo whereas grass and grasslike plants increased in importance as the season progressed. More acorns, dead leaves and pine needles were consumed with the increasing severity of the fall/winter period. Excessive damage to pine trees did not occur until other forage was consumed and during the fall/winter months when green forage was scarce. Diets of dairy and meat-type kids were similar, indicating that breed was not an important factor to manipulate vegetative composition. Understory vegetation can be preserved or destroyed depending on the stock density and frequency of regrazing. More than 988 "goat days" of feed per hectare were obtained from a typical woodlot without destroying the existing vegetation (J. C. Langston, unpublished). Brush goats were grazed two consecutive years, once in spring and once in late summer, at a stock density of 86 animals/ha for 3 to 5 d periods. Goats readily browsed honeysuckle, brambles, privet (Ligustrum vulgare), kudzu (Pueria lobata) and hardwood leaves and seedlings. Conversely, goats did not graze nimblewill (Muhlenbergia schreberi J. F. Gmelin), wild strawberry or yellow-crownbeard (Phaethusa occidentalis L.), regardless of stocking pressure; the density of these three species actually increased during the course of the experiment.
KUDZU IN PINE PLANTATIONS
Kudzu is one of the most aggressive competitive plant in southeastern forestland. Herbicides have been used to control kudzu but these chemicals are expensive and repeated applications are usually required. In addition, environmental concerns associated with the repeated use of chemicals cannot be overemphasized. Goats may offer a viable option to achieve management and control of this unwanted plant while providing additional income to farmers through meat goat production. In Alabama, growing Angora wethers grazed on kudzu in a loblolly and longleaf pine plantation for six weeks (September 14 until October 26) gained 160 and 180 g/head/day, respectively, when stocked at 10 or 20 goats/ha (Bonsi et al., 1991). Both groups were in good, healthy condition at the end of the grazing period and had an average body condition score of 5.0 out of a scale ranging from 1.0 to 10. The percent of damaged pine trees increased with increased length of time that the goats remained in the study area. In another study, growing goats (breed and sex not reported) rotationally grazed on kudzu-infested rangeland at a stocking rate of 27 animals/ha gained 160 g/d (Woldeghebriel et al., 1992).
Given a choice goats will often obtain more than 50% of their daily ration from browse. However, goats will perform well in grazing situations given that grazing management practices match their grazing behavior. A search of the literature indicated that grazing research data relevant to the Southeast are scarce.
Hart and coworkers (1993) grazed 6 to 8 mo old Alpine, Angora and Nubian kids on high quality wheat (Triticum aestivum L.) or low quality, dormant bermudagrass (Cynodon dactylon L. Pers.) for 54 d. Six goats of each breed were assigned to each of two high quality or two low quality pastures. Animals grazed on bermudagrass also received daily 200 g of a 24% CP supplement. The in vitro organic matter digestibility values were 66% for the wheat pasture and 32% for the bermudagrass (Table 8). Goats grazed on the wheat pasture gained 50 g/d vs 10 g/d for animals on bermudagrass (P < .02; Table 9). Angora kids gained the most weight on wheat (62 g/d; P < .05) and the least weight on bermudagrass pasture (-8 g/d; P < .05) compared to the other goat breeds. Angora goats appeared to be more sensitive to nutritional stress than Alpine and Nubian breeds, presumably due to greater nutritional requirements associated with fiber production.
Tannins are known to bind protein in the rumen, thus preventing bloat and decreasing ruminal proteolysis. Therefore, low levels of tannin may be a desirable component of forage legumes. Hart and Sahlu (1993) established two replicate pastures (.92 ha) to either sainfoin (Onobrychis viciifolia Scop. cv. Renumex; moderate tannin level) or alfalfa (Medicago sativa L. cv. Cimarron; low tannin level). Pastures were divided into six paddocks, grazed for 1 wk and rested for 5 wk. Yearling Angora doelings (17 to 32 kg BW) grazing sainfoin for 12 wk gained more weight (Table 10) than those grazing alfalfa. In addition, ruminal pH and ruminal ammonia concentrations were lower for goats grazing sainfoin. The greater weight gain and lower ruminal pH and ammonia level of goats grazing sainfoin were consistent with a lower ruminal degradation and increased bypass of protein associated with the protective role of tannins. The difference between pre- and postgrazing forage CP and NDF indicated that diet selection enabled goats to increase the quality of their diet (Table 10). In addition, the lower CP concentration in sainfoin was apparently more than compensated by a lower ruminal degradation due to the binding of proteins by tannins.
Limit-grazing has been used as a strategy to extend the grazing season or as an alternative to feeding concentrates to grazing animals. Hart and Sahlu (1995) evaluated two systems of overwintering mature, pregnant Angora goats with two pastures per treatment. Does were randomly assigned to 1.03 ha pens of standing dormant forage and fed chopped bermudagrass hay (4.0% CP, 48.2% ADF). One treatment was supplemented with 454 g/head/d of a protein supplement (16% CP, 3 Mcal/kg DM) whereas the second treatment was limit-grazed 2 h daily on a winter wheat-ryegrass (Lolium multiflorum) pasture (17.2% CP, 24.8% ADF). The study started in late November and ended in mid-April, when the first doe kidded. Hay was fed in the morning and supplement in early afternoon. Limit-fed does had daily access to winter pasture in early afternoon for 2 h. Supplemented does lost 6% BW during the experiment whereas limit-fed does maintained BW (P < .05; Table 11). Due to today's feed costs, limit-grazing does daily for a restricted period should prove to be more economical than feeding concentrate supplements.
Aeschynomene (Aeschynomene americana) , an annual legume preferred by white-tail deer, was used as a component of a pasture system and continuously or rotationally grazed by does and growing kids in Louisiana (Joost et al., 1990). Animal performance was compared to a bermudagrass/yellow foxtail/dallisgrass (Cynodon dactylon L. Pers./Setaria lutescens/Paspalum dilatatum) control pasture. In 1987 and 1989, aeschynomene comprised approximately 34% of the available forage present. In 1988, a drought resulted in a poor stand of aeschynomene that only comprised 9% of the available forage. The remainder forage mainly consisted of the grasses found in the control pasture. Does gained more weight on the rotationally grazed treatment during the initial year of the study. On the other hand, there were no differences in kid gains among the treatments in either of two years of the experiment. In 1987 and 1989, rotational grazing lengthened the grazing season by 30 d compared to continuous grazing.
Coastal bermudagrass and tall fescue (Festuca arundinacea Schreb.) are commonly grown grasses in the Southeast. Luginbuhl and Johnson (1982) and Luginbuhl (1984) fed Coastal bermudagrass harvested at 7 and 12 wk of age and tall fescue harvested at 6 and 9 wk of age to 8 growing Toggenburg wethers (17.9 kg BW). In addition, goats received 100 g of ground corn daily. Results showed that regardless of maturity, these hays were of insufficient quality to meet the nutritional requirements of young growing goats (Table 12). Six months old Stiffleg and Stiffleg X local brush goats fed hay (14% CP) and a 16% CP grain mix grew faster (Poore and Green, 1995) than goats receiving hay alone (Table 13). However, animals on both treatments grew rather slowly and had a poor feed conversion. Costs of production indicated that supplementing this type of goats after weaning is not economical.
Tree legumes may be utilized to increase intake, digestibility and performance of low quality forages by providing a high protein supplement. Mimosa (Albizia julibrissin), honey locust (Gleditsia triacanthos L.), mulberry (Morus alba, Morus rubra, Morus negra), willow (Salix spp.) and black locust (Robinia pseudoacacia L.) are fodder trees that grow in the Southeast. However, no research is available concerning their use in diets for growing goats. In Jamaica, Richards et al. (1994a) investigated the replacement value of the tropical tree legume Gliricidia sepium for a concentrate in kinggrass (Pennisetum purpureum) based diets for growing goats (Table 14). Intact male goats (Toggenburg, Anglo-Nubian and Saanen) were fed three diets containing 50% fresh chopped kinggrass, various amounts of concentrate and either 0, 20 or 40% Gliricidia sepium. The level of gliricidia in the diet had no influence on voluntary intake (Table 15). On the other hand, organic matter and NDF digestibilities decreased linearly (P .01 and P < .06, respectively) with increasing level of gliricidia. Furthermore, increasing the level of gliricidia in the diet resulted in a linear decrease (P = .06) in daily gain whereas gain/feed ratio decreased quadratically (P < .04). The authors concluded that low available dietary energy resulting in low N digestion and assimilation was likely responsible for the low animal performance observed on gliricidia-supplemented diets. The same authors (Richards et al., 1994b) observed no reduction in milk production by lactating goats when up to 50% of the concentrate N was replaced by gliricidia and Leucaena leucocephala in isoenergetic and isoproteic diets.
Goats will continue to play an increasingly important role as biological control agents. In addition, the recent importation of the Boer breed already has resulted in increased interest in meat goat production and research. However, the findings described in this review were for the most part derived from research with dairy and Angora goats, and may not necessarily apply to goats with a higher growth potential such as the Boer and meat-type goats upgraded with Boer genetics. Furthermore, many areas of production research are lacking data or are yet to be investigated. It is concluded that research focusing on forage evaluation, byproduct utilization, feeding strategies and the development of economical systems is urgently needed to meet the needs of this emerging industry.
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