The Boer Goat (Part 1)
Origin, Adaptability, Performance Testing,
Reproduction and Milk Production
By: N. H. Casey and W.A. Van Niekerk
Department of Livestock Science, Faculty of Agriculture, University of Pretoria.
0002 Pretoria, South Africa (21 May 1988 )
Casey, N.H. and Van Niekerk, W.A., 1988. The Boer Goat I. Origin, Adaptability, Performance Testing, Reproduction and Milk Production. Small Rumin. Res., 1: 291-302.
Boer goats evolved in Southern Africa from indigenous African and introduced European stock. Breed standards of the Boer Goat Breeder's Association (of South Africa) stipulate color to be white with red head and blaze, pigmented skin and good, functional conformation. Boer goats are hardy, graze a wide spectrum of plants, grasses and shrubs, effectively combating bush encroachment, have low water turnover rates and low internal parasite infestation. Does are early breeders, polyoestrous and may be synchronized with intravaginal progestogen or PMSG. A 70% kidding rate is reported with AI. Anaplasma ovis infection of does, transmitted transplacentally to the fetus causes abortions and neo-natal mortalities. Milk yield averages 1.5 to 2.5 kg/day with 43 g/kg protein and 77 g/kg fat contents. Libido and semen quality of bucks varies seasonally. Performance testing aims to measure dam's characteristics pre- and post-weaning, feed efficiency of kids under standardized conditions, and qualitative and quantitative carcass evaluation of sire's progeny. The future of Boer goats lies in performance testing for economically important traits.
Livestock production in Southern Africa occurs in two categories: subsistence farming and commercial production. Subsistence farming is practiced mainly by rural Africans in still distinctly tribal areas where Western economic systems have not invaded African traditions and livestock are an integral part of the rituals of tribal community life (Schapera, 1959; Tapson, D.R., 1986, personal communication). Land is tribally owned and held in trust to provide the resources of subsistence. Thus, little livestock enters markets of metropolitan areas. Supplies to these markets come from commercial producers who are mainly of European origin. Goats are farmed by the first group to provide meat, milk and occasionally cash income, but in the second category, goats are a source of cash flow, usually integrated with other farming activities (Marincowitz, 1985). In both instances, the qualities sought in goats are the same: high prolificacy with good mothering abilities, adaptation and a consumable, marketable carcass.
In rural areas, the local, unselected Boer goats are milked for home consumption. Keeping dairy goats is a very small industry in Southern Africa, numbering only a few hundred, which is a pity considering the efficiency of dairy goats. They make no significant contribution to meat supplies either. In subsistence farming, milk and meat are neither primary nor secondary products, both are highly prized essentials. In the commercial sphere, meat is the primary product, with no emphasis on milk production other than the need to raise a crop of kids.
The most commonly kept goat in rural areas is the unimproved "Boer" goat, boer is "farm" in Dutch. These are typical of the goats found all over Africa and parts of Asia, lean, long-legged and with a variety of coat colors. Most are short-haired. However, indigenous goats, close to the equator, are mostly short legged and short-eared, which will not be discussed in this review. The objective is to present characteristics of the improved Boer goat, which is primarily a meat producer. This breed is regarded as the key to upgrading rural goats for meat production (Devendra and Burns, 1970; Owen et al., 1978); compared to Botswana goats and sheep they are superior meat producers.
The origin of Boer goats is vague and probably rooted in ancestors kept by Namaqua Hottentots and migrating tribes of "Southern Bantu" people (Barrow, 1801; Epstein, 1971; Mason, 1981; Campbell, 1984). Other influences probably from India (Pegler, 1886) and Europe (Schreiner, 1898) also added ancestors. The occurrence of polledness indicates some possible influence of European dairy goats (Anonymous, 1960). Evidently, the Boer goats contain genes from these pools, especially considering migratory and trade practices of early inhabitants of Southern Africa. No differences have been found in gene frequencies of blood polymorphisms between present goat populations and the Boer goat breed (Osterhoff et al., 1987).
As goat farmers became more settled and began to breed for more distinct characteristics in the Eastern Cape region (1800 to 1820), the common Boer goat evolved as a compact, well-proportioned and short-haired animal (Van Rensburg, 1938). By the beginning of the 20th century, the emergence of a distinct breed was evident, since the number of farmers had succeeded in breeding improved types of goats with good overall conformation, high growth rate, high fertility, and short hair with red markings around the head and shoulders (Steyl, 1966). Breeding experiments indicate that one major gene may be responsible for the white coat color and red head (Osterhoff et al., 1987). In July 1959, breeding and selection became regulated with the founding of the Boer Goat Breeder's Association (of South Africa) and a truly improved Boer goat emerged because of formulation of breed standards as guidelines for selection. They describe morphological characteristics, but the stage is set to include production characteristics as more breeders recognize and accept the merits of performance testing.
Breed standards stipulate the ideal color of Boer goats to be white with a red head and a blaze. A limited number of red patches are allowed. A pigmented skin is preferred, particularly in areas with no hair cover. Furthermore, Boer goats must be robust, with good conformation and have a Roman nose. Legs must be short, well fleshed with good thighs and hindquarters (Campbell,1984), which is important for good carcass characteristics. Faults for culling are a hollow forehead, narrow mouth, folded ears, under-shot jaws, hollow back, weak pasterns, front x-shaped legs, small testes, hooves turning in or out, long, rough and furry hair covering, thick, big teats, and less than 25% pigmentation. No performance criteria are stipulated such as semen quality, growth rate, feed conversion, fertility, mothering ability, milk production, or carcass quality characteristics. Discrimination against furryness has been questioned as the Boer goat's potential to produce cashmere hair has been realized recently and is being investigated.
Versatility of farm animals in their ability to adapt to various climates and production systems is an economically important characteristic with direct bearing on producing ability, demand for breeding stock and return on investment. Adapted animals, in harmony with tropical environments, have resistance to endemic diseases, are more heat-tolerant and look flourishing (Bonsma,1970). In general, the Boer goat is regarded as very adaptable, thriving in all climatic regions of Southern Africa, including the mediterranean climate, the tropical and sub-tropical bush, and the semi-desert regions of the Karoo and greater Kalahari.
Reproductive performance is an indicator of environmental compatibility. Boer goats have a reputation for high fertility, averaging 98% of does bred under good management and nutrition (Campbell, 1984).
Adaptability of improved Boer goats was challenged in a comparative study under harsh managerial and environmental conditions, in the sub-tropical bushveld near the Tropic of Capricorn (Ramsay et al., 1987). A herd of 394 traditional African goats (bucks and does) and 58 Boer goats (bucks and does) from various areas of South Africa, was established on a bushveld farm in Northern Transvaal. In the first year (1984), both groups suffered kid mortalities. Traditional goats recorded 102% kidding followed by 14% mortality, compared to 120% kidding of Boer goats followed by 76% mortality. In the second year, the performance of both groups improved. Traditional goats had 112% kidding and 10% mortality, but Boer goats had 137% kidding and 30% mortality. Lack of survivability by Boer goats was due to a number of factors, including predators. In the first year, the problem was aggravated by severe drought. A high proportion of Boer goat kids were abandoned by their dams, no doubt in response to the extreme conditions. Improvement in survivability of Boer goats could be expected with better conditions and improving resistance to endemic diseases such as heartwater (Rickettsia) and anaplasmosis (A. ovis), although anaplasmosis infection was not diagnosed (Ramsay et al., 1987). Symptoms in does and neo-natal kids were subsequently described by Barry and Van Niekerk (1987) and Van Niekerk and Barry (1987) as due to an anaplasma infection. Does appeared to lack energy, became tired quickly and anaemic. This, instead of the drought, may have caused does not to be able to support their offspring (Ramsay et al., 1987). Kids born with A. ovis parasite were weak, anaemic and just lay on the ground splay-legged.
Foraging preferences of goats cause them to graze a wider spectrum of plants than other small stock. Boer goats are inclined to forage from the top downwards, from heights of 160 cm to 10 cm (Aucamp and Du Toit, 1980) and with a ratio of 82% bush and 16% grass (Viljoen, 1980). Bush encroachment and regrowth has been combatted successfully with Boer goats (Du Toit, 1972), who browse leaves but also debark stems and branches, particularly of young plants. The practice of using goats in bush control has been successful (Provenza et al., 1983). Neither veld conservation practices, nor veld burning, nor planned pasture management with cattle has equalled the impact of goats in combatting bush encroachment (Aucamp, 1979; Tainton, 1981). This is an economically important trait of goats. Foraging habits may contribute to Boer goats having low infestations of internal parasites (MacIvor and Horak,1984).
Goats appear to be less particular in quality of diet selected than cattle and sheep, quality being defined in terms of in vitro digestibility. Squires (1982) reported such a finding between sheep and goats foraging a woodland community with an understory of shrubs and a herbaceous layer of grasses and forbes. The spectrum of plants selected by goats overlapped that of cattle. Boer goats grazing on semi-desert scrub of the Karoo selected material of significantly less (P<0.05) digestible organic matter than did Dorper and Merino sheep (Zeeman et al., 1983). Goats were better selectors, however, of material with sufficient digestible organic material at or exceeding their maintenance needs than were cattle, which is expected since the Karoo is not a natural habitat of cattle. In other studies by Hofmeyr et al. (1965), Boer goats suffered less weight loss than Angora goats, Dorper, Karakul or Merino sheep over a 12 month period and feed supply rather than climate appeared to be the limiting factor. Ability of goats to utilize tropical and scrub pastures more efficiently than cattle may be due to their smaller size in relation to limited food supply and their ability to exploit available feed resources selectively (Van Soest,1987). This behavioral trait of goats to forage selectively facilitates their ability to survive under harsh tropical and semi-arid conditions.
In a comparative trial between Boer goats and wild ungulates, kudu (Tragellaphus strepsiceros) and impala (Aepyceros melampus), Owen-Smith and Copper (1987) found Boer goats less selective among woody plants than kudu or impala. Of total time spent foraging, goats spent 45% on woody browse vs. 64% by kudu. Boer goats accepted more plants with high proanthocyanidin content than wild ungulates, although preferring these plants less than low tannin species. Tolerance of tannins by goats may be an example of evolutionary physiological adaptation. According to Van Soest (1987), quoting Hoffman (in press), enlarged salivary glands and extensive ensalivation may produce mucus that binds tannin and saves protein in leaves for digestion. On the other hand, rumen microbial adaptation may increase protein synthesis instead of binding tannins (Horvath, 1981), which would require increased amounts of urea and other non-protein nitrogen (NPN).
Fibre digestive capacity of Boer goats is currently being investigated. In one experiment, the Boer goat seemed to be less effective in the digestibility of fibre of Cenchrus ciliaris hay, than Dorper sheep (Van Niekerk et al., 1985). In a second experiment, castrate Boer goats were fed five diets for 90 days that were equal in N, Ca, and P but had increasing levels of C. ciliaris hay (28, 32, 57, 71, 85%) which were balanced against decreasing levels of maize (62, 47, 32, 18, 3%). Apparent digestibility coefficients (ADC) of crude fibre were, for diets 1-5: 37, 49, 59, 58, 58%. Relatively low ADC-values for high fibre diets could be due to energy shortage in the rumen. Fibre digestibility decline with high maize contents probably was due to lower cellulolytic rumen activity (Van Niekerk and Casey, 1987).
Gihad et al. (1980) concluded that goats are generally better digesters of crude flbre than are sheep, and thus, appear to be better utilizers of poor roughages. Since goats select a different spectrum of herbage than cattle and sheep, which may be of lower quality on laboratory analysis, and since goats are more tolerant of some noxious plant compounds, and may be better digesters of crude fibre, quality standards for diets of meat goats need to be defined carefully.
Boer goats, like breeds described by Shkolnik and Choshniak (1985), are more adapted to hot than cold environments because of small size, large surface area to body weight ratio, ability to conserve water, limited subcutaneous fat cover and the particular nature of their coats. Regarding water metabolism, Boer goats have a lower water turnover rate than the Namaqua Afrikaner, Merino and South Down sheep (Erasmus,1967). Tested diurnally at 21° C and 37° C, Boer goats drank 40% less tepid water per day per metabolic size than sheep. Goat's faeces were also drier, urinary volume decreased at the higher temperature and was lower than that of sheep.
Performance testing of Boer goats started in 1970 under the (South African) National Mutton Sheep and Goat Performance and Progeny Testing Scheme. This is the second phase in the development of the Boer goat breed. The first phase was the adoption of breed standards which developed uniformity of type, color, hair and body conformation. It also united breeders with a common purpose and identity. Performance testing was first viewed with trepidation until the merits were demonstrated and then acceptance began to gain momentum. Hofmeyr (1978) maintained that stud breeders will continue to be an influential group in any effort to breed and improve livestock. Breeding goals must include putting higher emphasis on reproductive rates, reducing the number of traits selected for by excluding those of doubtful importance, and maintaining effective herd sizes and composition.
The Boer Goat Performance Testing Scheme provides for performance testing and selection of goats, specifically for meat production, according to the following five phases of determination:
A. Dam's characteristics, her milk production and growth rate of her kid(s) up to weaning age.
B. Post-weaning growth rate of the kid(s) as measured at various ages.
C. Efficiency of feed conversion and body weight of male kids under standardized conditions at a central testing station.
D. Post-weaning growth rate of male kids under standardized conditions.
1) on a farm under supervision and direction of the Animal and Dairy Science Research Institute, Irene, R.S.A. and
(2) at a central location of a co-operative institution, also under the auspices of the Institute.
E. Qualitative and quantitative carcass evaluation of a buck's progeny.
Progress with phase B is in Table 1. Up to 1982, average weight of male kids increased by 0.7 kg and that of females by 0.4 kg annually on average. The subsequent drop can be ascribed to the four severe drought years after 1982. Number of participating breeders had risen from 2% to 5% of the total and is attributable to implementation of phase D(2) which tests male kids under standardized conditions. Breeders seem more interested in testing males, since performance data are becoming important in marketing breeding stock. The first 75 bucks were started on phase D(2) test during May 1986, but collated results are not yet public (at the time this article was written in 1988).
The present "improved" Boer goat evolved from a narrow base with many elite studs having no more than 50 does (Barnard, 1980). An analysis of the breed structure of Boer goats has not yet been made, but a strong genetic influence of elite studs on general breeder farms has been noted. Traits like undershot jaw and bow-leggedness are genetic undesirables and have wrongly been dismissed as consequences of nutrition by some breeders.
100 Day Body Weight (kg) of Performance Tested Boer Kids, (1970-1984) (1)
YEAR BUCKS DOES
1970 24.0 21.9
1971 25.4 23.0
1972 26.3 24.1
1973 22.1 21.1
1974 ---- ----
1975 23.6 21.7
1976 ---- ----
1977 22.4 21.3
1978 27.1 24.9
1979 36.5 29.2
1980 29.0 25.3
1981 ---- ----
1982 32.3 27.8
1983 25.6 24.6
1984 23.6 19.0
(1) Campbell, 1984.
High rates of reproduction and low post-natal mortality are most important requirements for meat producing animals; these criteria apply to goats more than other domestic ruminants because of higher average litter sizes (Devendra and Burns, 1970; Shelton, 1978). High prolificacy, good fecundity and mothering ability of Boer goats are shown in Table 2. These are national averages of participants, gathered under phase A of the Performance Testing Scheme (Campbell, 1984). Litter size of 1.93 kids per parturition is above averages in other reports. Selection for fecundity, coupled with good management could raise this value to 2.25 or more.
Boer Goat Does Kidded, Kids Born, & Kids Weaned Per 100 Does Mated (1)
Females Kidded 98
Singles Born 24
Twins Born 116
Triplets Born 45
Quadruplets Born 4
Number of Kids Per Parturition 1.93
Singles Weaned(2) 26
Twins Weaned 112
Triplets Weaned 4
(1) Campbell, 1984.
(2) Some single kids were born as twins or triplets but reared as singles
The kids of Boer goat does are early breeders, reaching puberty at 6 months of age, and are polyoestrous with a peak of sexual activity in the South African autumn and a low in spring and summer (Kupfer, 1928; Hofmeyr et al., 1965, 1966; Skinner, 1972; Greyling and Van Niekerk, 1987). An extended breeding season is widespread among goats in the tropics and subtropics (Devendra and Burns, l970) and it is particularly advantageous to meat production. By mating twice per year or three times per two years, the number of kids per doe per year, and essentially the potential gross meat yield, can be raised dramatically. This was achieved when number of kids per doe per year was raised from l.89 to 3.60 by mating twice a year (Hofmeyr, 1962; Skinner and Hofmeyr, 1969). Achievement was ascribed partly to does being on a high nutritional regime and partly to weaning at 6 weeks of age. Mere presence of males brought does into oestrus for the second season, within 8 days of introduction of males. Apparent decline in male libido in spring and summer had to be taken into account carefully when twice yearly breeding was practised. Drop in libido coincided with a significant drop in percentage of live sperm in the Southern Hemisphere spring (October) and a non-significant decline in sperm density in November (Greyling and Grobbelaar, 1983). Skinner and Hofmeyr (1969) countered declining libido successfully by treating bucks with 500 IU of pregnant mare serum gonadotrophin (PMSG).
Synchronization of oestrus of Boer goat does has been achieved successfully with intravaginal progestogen or 300 IU PMSG. The effective period of intravaginal progestogen administration was from 12-18 days and the conventional practice was 14 days as in sheep (Greyling et al., 1985). Young buck kids also mature early and can be used for breeding successfully at 168 days of age ( Skinner, 1972). Six-month-old bucks are mated with 15 does, and from 9 months on they can be mated with 30 does, depending on conditions, or this can be doubled where handmating is practised (Skinner, 1972).
Lawrenz (1987) reported successful in-and-out-of-season artificial insemination of Boer goats with frozen semen preserved in tris-based diluent with egg yolk, and a concentration of 200 x 10^6 spermatozoa. A total of 46 does were inseminated in October (Southern Hemisphere out-of-season), 12-14 hours after onset of standing heat with a non-surgical, intra-uterine technique. A 61% kidding was achieved. Repeated in the breeding season, a 71% kidding was achieved.
Abortions have often plagued Boer goats in some areas. Due to weak appearance of does, the abortions were ascribed to undernutrition. Subsequently, Coetzer and Van Niekerk (1987) investigated the problem experimentally and reported that even severe undernutrition did not cause abortions. Instead, the cause was demonstrated to be due to Anaplasma ovis infection (Barry and Van Niekerk,1987; Van Niekerk and Barry,1987). Not only were the aborting does red blood cells parasitized, but also those of the aborted fetuses. It was concluded that A. ovis is transmissible to goats and is capable of transplacental migration into the fetus. The organism is therefore likely to cause abortion in goats in areas where it is prevalent.
Under natural conditions, milk production is an extension of reproduction, but Boer goats have no milk producing reputation since they have not been selected for this trait. Unimproved Boer goats are milked to provide food in rural subsistance farming. Under extensive, semi-hardy veld conditions, Boer goat does, (2-6 teeth in age), with singles to triplets had average daily milk productions of 1.5-2.5 kg (Table 3) (Raats et al., 1983). The range was due to litter size and lactation number.
Average yield of 1.5 to 2.5 kg/day may not compare well with intensively selected dairy goats. but presence of milk ancestry and selection for milk production could raise the capabilities of Boer goats. This would require a higher nutritional regime, and if does in this experiment had been fed a supplement, their average production could have been 2-3 kg/day. Evidence is in two-year old does whose production peaked at 3 kg/day. Estimated amounts of total milk, protein and fat available to kids during the first 12 weeks of lactation are in Table 4 (Raats et al., 1983). Calculated values for protein and fat contents of Boer goat milk are 43 g/kg and 77 g/kg, respectively.
Mean Daily Milk Production & Milk Composition During First 12 Wks of Lactation Of Boer Goat Does (1)
Doe Litter Milk Yield Milk Composition------------------
Age Size kg/day(2) Protein Fat Total Solids Lactose
% % % %
2 Singles 1.5(a) 4.5 7.5 17.3 4.7
2 Twins 1.9(b) 4.4 7.0 16.8 4.7
2 Triplets(3) 2.3 4.2 6.4 15.8 4.6
4 Singles(3) 1.8 4.5 7.7 17.9 4.9
4 Twins 1.9(bc) 4.3 7.4 17.1 4.8
6 Singles 2.1(bc) 4.4 9.4 19.2 4.7
6 Twins 2.2(bc) 4.1 8.1 17.4 4.7
6 Triplets 2.5(c) 3.9 7.6 17.0 4.7
(1) Raats et al., 1983.
(2) Means in the same column with different superscripts (a,b,c) differ significantly at the 5% level of probability.
(3) Data unreplicated and excluded from the overall analysis of variance.
Estimated Amounts Of Total Milk, Protein And Fat Available To Individual Kids During
First 12 Weeks Of Lactation of Boer Goats (1)
KID GROUP Doe Age Available Nutrients-------------------
(years) Milk (kg) Protein (kg) Fat (kg)
Single 2 123.3 5.5 9.3
Twin 2 79.5 3.5 5.6
Triplet 2 63.3 2.7 4.0
Single 4 154.1 6.9 11.9
Twin 4 83.6 3.6 6.2
Single 6 175.2 7.7 16.5
Twin 6 91.6 3.8 7.4
Triplet 6 69.1 2.7 5.3
(1) Raats et al., 1983
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Reprinted With Permission Of N. H. Casey and W. A. van Niekerk