The Australian Bush Goat
The harvest of the bush goat populations for meat commenced in 1953 and has continued sporadically ever since. Components of the commercial harvest include field shot animals, live exports, and abattoir slaughterings, with the abattoir-slaughtered component being predominant. It is only the field shot animals that are classified as game meat. Abattoir-slaughtered bush goats are subject to the same meat regulations as farm-raised animals. In recent years the commercial harvest has stabilised at about one million animals per annum. In general, on account of size or condition, only 80-90% of animals mustered have commercial value. The non-commercial animals are usually culled at the point of harvest. When these plus other goats shot for sport or in non-commercial culling operations are included, the total offtake in recent years has probably been about 1.3 million animals.
It is generally accepted that early mariners introduced goats into coastal Australia during the 17th century, either as a result of shipwrecks or in a deliberate attempt to provide a source of food on off-shore islands.
Goats also came to Australia in 1788 with the first European settlers who used them as a source of meat, fibre and skins. Some animals escaped to become feral and, on occasion, drought and low goat fibre prices led to the abandonment of whole herds .Distribution
Bush goats are now widely distributed throughout mainland Australia, with the largest populations being in the arid and semi-arid zones of Western Australia, New South Wales, South Australia and Queensland. Isolated populations and lower densities occur throughout many other parts of Eastern Australia and on coastal islands. The size of the total population is unknown and probably fluctuates considerably depending on rainfall and control strategies. The distribution of bush goats in surveyed areas is shown in figure 1. The two main factors affecting this distribution are predation and environment. Shelter is essential to limit the effects of predation. Bush goats are dependant on drinking water being available and, therefore, are not found in desert environments.
Figure 1. Distribution and relative abundance of bush goats in the rangelands.
Hunting by man is the main reason why bush goats are found in areas of low human population. They have adapted quickly to the drier, harsher conditions and goat numbers are affected only by the intrusion of man for commercial motives. Rough topography and dense vegetation have allowed, in some cases, bush goat populations to stabilize in agricultural areas.
Dingoes and foxes prey upon both the young and mature goat. This has caused movement into dog-free areas. In some areas, however, when conditions are particularly favorable, dingoes and goats can coexist, although the goat population is scattered into smaller groups.
Other predators (bush pigs and eagles) have been shown to reduce rearing survival percentages, but their aggressive activity has not restricted the distribution of goats.
The greatest density of bush goats is found in the Acacia shrublands (mulga) of Queensland, New South Wales, South and Western Australia.
Bush goats also occur within the wheat and sheep and high rainfall zones of southern and eastern Australia, but are usually located in the rough terrain of the poorer soil types.
A main vegetation type favoured by bush goats is hilly terrain in the arid zone, which has some shrub cover and a scattered herb layer. Bush goats are not usually found in open grasslands unless rough terrain is available nearby for refuge.
An accurate estimate of the bush goat population in Australia is not possible, due mainly to the effects of seasonal conditions and hunting pressure. Females are prolific breeders under favourable climatic conditions and the base population can increase dramatically within a short period.
A diet selected by bush goats is extremely variable and is principally governed by the choice available. Bush goats are herbivores, and can switch from browsing to grazing and even to foraging for litter to survive. They show a growth and breeding response to flushes of herbage and shrub growth after rain yet are able to select a maintenance ration from shrubs and trees in most areas during dry periods.
In restrictive environments their dietary habits affect tree and shrub regeneration of palatable species.
In semi-arid areas goats add to an already excessive grazing pressure on herbage caused by commercial sheep and cattle enterprises.
Movement of bush goats is caused by the failure of food and water supply on the home range, by phenomena associated with breeding and harassment by humans.
Most goats prefer a limited home range, particularly during dry times if there is no alternative water or good feed supplies. During dry periods, large numbers of bush goats come together at water points. This large herd may contain different range groups; the effect upon social and breeding behaviour is not known.
Male kids leave their mothers at puberty and run separate in small bachelor herds. As does come into oestrus, during their normal breeding season or following the first rains, the bucks disperse into small harem groups. Purely female only herds may be found, comprising pregnant does or does not cycling because of poor nutrition. Bush goat herds rest at night in traditional campsites. Composition of groups and attendance at campsites is variable, reflecting seasonal changes in dispersion and male movements.
Bush goats use high or inaccessible areas as campsites probably to reduce the risk of predation.
Goats prefer to graze with heads into the wind. Bush goats have been observed feeding out long distances under the influence of wind and then return to their normal night camp.
Drinking frequency is partially influenced by social behaviour, the watering point being one of the main centres of inter-goat encounter in the home range.
Individual goats vary considerably in size and weight. At birth, bush kids weigh approximately 2.5 to 3.0 kg with males tending to be heavier than females. After weaning, growth varies with nutrition, season, breeding activities and age. The average growth for males is around 65 g/day at 9 months to around 40 g/day at 18 months.
In Australia the most common goat colour of bush goats is white. Many goats have multi coloured coats and there is considerable variation within and between populations.
Bush goats appear to be relatively free of bacterial diseases except Caseous lymphadenitis (CLA - cheesy gland), which has been detected in small proportions in abattoir surveys.
Lice and mite infestations are widespread, parasite loads vary among individual animals and among range groups.
Feral goats are widely believed to represent an ecological threat to some areas of the Australian rangelands. Feral goats compete with other herbivores and in some circumstances directly reduce grazier returns from sheep and cattle. In addition, feral goats have the potential to act as a disease reservoir in the event of an exotic disease outbreak such as foot and mouth . Although eradication of feral goats is generally considered to be both economically and technically unachievable over most of the rangelands, it remains as the stated goal of some land management agencies.
Control and management is essential for proper utilization of goat fibre and goat meat products; it will benefit the producer and benefits the environment.