COMPLEMENTARY GRAZING OF PASTURES BY GOATS, SHEEP AND CATTLE.
FIRST PUBLISHED JANUARY 1985
AUTHORS: Bruce McGregor, Livestock Research Officer, Department of Agriculture, Animal Research Institue, Werribee, Vic. 3030________________________________________
Over the last decade the numbers of farmed fibre producing goats has increased rapidly. Considerable interest has been expressed in using goats to diversify enterprises. Are there any advantages to be gained (complementary effects) from grazing goats with sheep or cattle? This note will discuss some findings relating to complementary grazing of pastures but will exclude any discussion on benefits from grazing weeds.
Experiments in Texas and parts of Africa have shown advantages in running goats with cattle and or sheep. However, the environments have been arid or semi-arid with a high proportion of scrub and tree vegetation. In many cases the plant communities have been very mixed in one case with over 230 plant species. The advantages gained in these environments by mixed grazing were based on different herbage utilization by the grazing species with goats utilizing more of the scrub and tree components than sheep and cattle, and sheep utilizing more scrub than cattle.
In Texas the profitability of ranches was improved by grazing all three species together and experiments are continuing to determine the appropriate proportion of cattle to sheep to goats. Plant species analyses indicated the stock consumed many of the same species but in different proportions. There were also many plant species which were not grazed by any animal species.
In New South Wales studies undertaken in semi-arid mixed woodland environments have indicated that sheep and goats can more effectively utilize available herbage compared to single species grazing. Again the stock consumed many of the same species but in different proportions.
In most of these studies large differences between years occurred. When fresh growing grass was available goats grazed grass and so directly competed with sheep. However when the grass died the goats consumed other plants more nutritious than dead grass, and so their diet diverged from that of sheep.
In these environments, goats are very flexible and opportunist in their dietary habits. They are fastidiously selective being able to select particular leaves or parts of individual plants. The studies show that goats are not obligatory browsers and that grasses are seasonally and nutritionally very important components of their diet.
GOATS AND SHEEP ON TEMPERATE PASTURES
Studies of the dietary components of grazing fibre producing goats on temperate pastures are very limited. In an experiment currently in progress at Werribee, Angora goats and Merino sheep are grazed at stocking rates of 7.5, 10 or 12.5/ha and in three combinations of animals goats only, sheep only and goats and sheep mixed in equal numbers (ie. 50/50).
The pastures consist of annual ryegrass, barley grass, silver grass and subterranean clover there is no browse available. (These pastures are therefore a lot more uniform and with less plant species, compared to the studies undertaken in arid environments). The pastures at Werribee germinate in March/April and mature (dry off) in early November. Animals must graze the dead pasture residues over summer until the next autumn break.
During 1981 and 1982 little influence on pasture composition was noted mainly as 1981 was at the commencement of the experiment and 1982 was a drought year. Low stocked goat paddocks did have slightly increased clover content in spring 1982. However, autumn 1983 was excellent for subclover germination. From July 1983, goat paddocks had significantly more clover than sheep only paddocks (see Table 1). By pasture maturation in November goats only paddocks had about 36% clover (seemingly unaffected by stocking rate) and sheep only paddocks averaged 10% clover. Mixed grazed paddocks at 7.5/ha were 'goat like' in terms of clover content, 10/ha was intermediate between goat and sheep (although still with twice the clover content of sheep only paddocks) and 12.5/ha was 'sheep like' but still with three times the clover content of 12.5/ha sheep only paddocks. On the mixed grazed paddocks it was apparent that sheep consumed clover especially at higher stocking rates.
These results and other observations at Werribee with feral and Angora x feral goats on irrigated ryegrass white clover pastures indicate that goats show a distinct preference for grass over growing clover. In 1983 the first obvious visual signs of Angora goats grazing green subclover occurred in October when pastures and the soil began to dry out. Over summer the goats consumed the dry clover residues and were seen scratching the ground digging up clover burr. High clover residues over summer helped the goats maintain liveweight until mid-January whereas sheep lost weight from mid-December. However sheep on mixed grazed paddocks were 1 to 5 kg heavier than sheep on sheep only paddocks, the difference being greater at 12./ha. In addition the goats tended to "mow off" the top of the dead residual grasses while the sheep grazed more at the base of the pasture during late summer and autumn.
TABLE 1. Pasture subterranean clover content in spring 1982 and during 1983. (Figures as % green subclover of total pasture dry matter)
So far the experiment has found that on mixed grazed paddocks there seems to be advantages to sheep at 10 and 12.5/ha in terms of live weight and wool production. In mixed grazed paddocks at high stocking rates goats are definitely disadvantaged and are lower in live weight, poorer in condition and produce lighter fleeces. There is some evidence that mixed grazing at low and medium stocking rates may help reduce internal parasite burdens of the goats compared to goats grazed alone at similar stocking rates.
The main problem with mixed grazing is to determine a stocking rate that is profitable for both sheep and goats. As the recommended stocking rate for Werribee is 10 dry sheep/ha it is apparent that mixed grazing at 12.5/ha could lead to problems it certainly does for the goats. As this experiment is still in progress we have not yet determined the recommended stocking rate for goats and so cannot draw final conclusions about mixed grazed goats and sheep. However, the evidence of a "goat effect" on pasture composition is of potentially great importance.
GOATS AND CATTLE
With regard to mix grazing of goats and cattle, no relevant research has taken place on pastures. However, a number of relevant points can be drawn from the Werribee experiment and general observations of goats. Clover ungrazed by goats in late winter and spring is likely to be grazed by cattle. Goats do eat coarse grass stems over summer and so will not only open up the pasture for cattle but will compete with cattle for these coarse grasses.
Unfortunately goats harbour some of the internal parasites of both cattle and sheep. The full significance of this is not known but on breeding properties the introduction of breeding goats could lead to increased internal parasite problems of calves and lambs.
SHEEP AND CATTLE
There have been two Australian experiments examining complementary grazing of sheep and cattle which are worth discussing in this Goatnote.
At Rutherglen Victoria, on annual pastures, the wool production and lamb growth from autumn-lambing flocks were improved by about 12% when sheep were grazed with cattle at comparable grazing pressure, instead of separately. This was achieved without any reduction of the growth of the cattle. When green pasture was scarce over the late autumn and winter, it was noted that the sheep grazed pasture around the cattle dung pats, whereas this was left untouched in the 'cattle only' paddocks. When the pasture was dry the cattle ate more of the coarser parts, such as grass stems. The sheep ate more of the finer parts such as shed clover leaf; in addition, they sometimes ate substantial amounts of clover burr, which was virtually untouched by cattle.
On perennial pastures at Canberra, mixed grazing led to increased productivity from spring-lambing ewes without any substantial effect on cattle production. There was an increase of 13% in the number of lambs weaned, weaning weights increased by 17% and the ewes cut 12% more wool.
In the Rutherglen situation the most profitable stocking rate for sheep alone was 8 1/2 ewes per hectare. The most profitable stocking rate for cattle alone was about the equivalent of 5 1/2 ewes per hectare. In this case it turned out to be more profitable to ignore the opportunity for better pasture utilization for mixed grazing at the same grazing pressure for the sheep and the cattle, and instead graze the sheep and cattle separately, each at their own most profitable stocking rate.
This is not true in all situations, however. At Canberra, where different types of sheep and cattle were used under different methods of animal management and with different pattern of pasture growth, there was no marked difference in stocking requirements of the sheep and cattle, and hence no such problems in grazing them together.
Some of the most important worm species do not transmit readily between sheep and cattle; therefore, sheep and cattle can complement each other in worm control, especially in the case of the troublesome Ostertagia species.
It appears that there may be complementary effects of grazing goats with sheep and cattle on temperate pastures. In particular there appears to be a "goat effect" in increasing clover content of growing pastures. However we have yet to determine the optimum stocking rate for goats and we have much to learn about the best ways of controlling internal parasites in goats. In situations where animals compete for winter feed there is unlikely to be great gains from complementary grazing. If the overseas situation is repeated in Australia (on pastures) then the replacement of a 1/4 or 1/3 stock numbers by goats might lead to some gains. Experiments in progress are examining many of these aspects.
© 1985 ACGA