Successful scrub feeding is not limited to the more palatable and nutritious species, especially during dry periods. Scrub with a higher fibre content, and so lower nutritive value, can be used (Table 1). Feeding urea molasses has broadened the range of trees that can be used for drought feeding.
The palatability of any one species may vary from paddock to paddock and from year to year. An assessment can be made only by offering a particular scrub to livestock and observing stock response in terms of palatability, feed intake and liveweight change.
Points to note when scrub feeding
- Cut only one species at a time.
- Provide sufficient leafy material to minimise the eating of twigs and branches.
- Follow a set feeding routine. It is common to cut two to three day´s supply, but daily cutting may be necessary in summer to avoid leaves withering. As the drought progresses, the foliage on uncut scrub dries out and fresh scrub may need to be cut daily.
- While stock are strong, cut the scrub most distant from water. Then cut closer scrub.
- If acceptance is poor, spraying with a molasses-water mixture may increase intakes, but some trees in every stand of scrub are unpalatable. Generally, older mulga trees are preferred to young ones.
- Pulling with a chain or bulldozing can reduce acceptance because of high dust levels.
- Consider the long-term environmental effects of pulling scrub. Leave strips of trees for regeneration, wildlife protection and the like.
Predisposing factors contributing to gastric impaction
- Cutting too little scrub, thus forcing cattle to eat twigs and branches.
- Scrub drying out, either through cutting excessive amounts or leaves wilting.
- Stock not drinking enough water.
Research at Charleville Pastoral Laboratory has demonstrated that supplements providing protein nitrogen (cottonseed meal), non protein nitrogen (urea), sulphur (sulphate of ammonia) and phosphorus (dicalcium phosphate) can be very beneficial to animals consuming fodder trees. These additional nutrients stimulate the rumen and increase feed intakes.
Providing molasses supplements on an irregular basis assists the passage of fibre.
The capacity for regrowth depends largely upon the kind of trees, seasonal conditions and the method of cutting. Trees such as mulga normally do not grow again if they are cut low or if they are pushed with bulldozers.
Wilga, vine tree, boonaree and kurrajong usually produce vigorous new branches if branches are cut off high enough so that animals cannot chew the young growing shoots.
Experience has shown that the most reliable regrowth from mulga takes place if the whole of the crown of the tree is taken out above the reach of the stock leaving the thin lateral branches below the sloping branches (leaders) intact. If mulga is scarce and individual trees need to be conserved, this is the wisest way to handle it.
Regrowth will occur if the centre is broken out with a front end loader provided some horizontal side branches (laterals) are left below the break.
In more recent years the more common method of felling mulga for stock has been the use of bulldozers, either by a single bulldozer or two bulldozers joined by a cable. Regeneration of mulga from seedlings following pulling is known to occur more rapidly if sheep are excluded from pulled areas.
Using chain saws, one man full-time can feed about 300 adult cattle per day. This estimate is for mulga and assumes that feeding conditions are excellent and a spare chain saw and parts are readily available.
Of course, if the scrub is being used as a supplement to dry pasture, labour requirements are lower.
After the drought
Heavy stock losses can occur when weak cattle ´chase the green pick´ following droughtbreaking rain. If possible, confine weak cattle and continue to feed scrub until sufficient grass has grown for them to get their fill without expending valuable energy.
|Common name||Palatability||Nutritive value||Comments|
|Apple tree||A||A||Well eaten - some seasons|
|Athel tree||A||A||Well eaten - short supply|
|Bauhinia||B||A||Deciduous - of little value late winter and spring|
|Beefwood||B||C||Leaves eaten by sheep|
|Belah||C||C||Eaten readily - twigs can be a problem|
|Bendee||B||B||No particularly palatable but often fed - can be poisonous at certain stages|
|Boonaree, Dogwood or Rosewood||A||A||Can cause prussic acid poisoning particularly at flowering or young growth stages|
|Boree||A||B||Eaten readily by sheep - very fibrous|
|Bottle tree leaves||A+||A+||Some trees appear to be toxic to hungry cattle|
|Bottle tree pith||B||C|
|Brigalow (15cm or less)||B||A||May eat young suckers as last resort|
|Budda sandalwood||D||C||Not readily eaten. Said to reduce impaction if fed with more fibrous scrub|
|Bulloak||D||D||Is eaten fairly readily - very fibrous|
|Bumble tree||A||A||Excellent fodder - short supply|
|Coolibah||B||C||Leaves of young trees eaten when half dry. Adult trees have been fed with urea/molasses|
|Currant bush||C||B||Not readily eaten|
|Desert gum or cabbage gum||B||B||Eaten fairly readily|
|Doolan||B||B||May be toxic to hungry stock|
|Gidyea||C||B||Not much in the area. Best to feed by fire to lift acceptance. Good results if eaten|
|Green wattle||X||X||Not touched by cattle|
|Ironbark||B||C||Eaten fairly readily when supplemented with urea/molasses|
|Kurrajong||A+||A||Has laxative effect. Very palatable and one of the best to feed|
|Leopardwood||A||A||Well eaten - short supply|
|Limebush||C||B||Young plants are unpalatable|
|Mimosa bush||B||A||Grazed by sheep|
|Mulga||A||B||Well eaten and a plentiful supply in south-west Queensland. Dense stands make easy pushing and cutting|
|Myrtle tree||B||B||Readily eaten by sheep and cattle|
|Old man saltbush||A+||A+||Self harvested|
|Plumwood or true sandalwood||A+||A+||Short supply|
|Popla box||C||C||Eaten if nothing else|
|Vinetree or supplejack||A+||A+||Excellent fodder - short supply|
|Wilga||A||A||Good fodder - palatability varies widely from year to year|
Scrub wilga (Turpentine wilga)
|X||X||Untouched even in drought|
|Weeping willow||A||A||Planted in damp areas. Winter deciduous. Eaten readily|
|Whitewood||A||A||Fruits poisonous but avoided by stock|
|Yapunyah||C||C||Leaves are eaten to some extent|