Diet components

Roger Sneath and Greg Bath
Department Agriculture and Fisheries

Introduction

Feedlotters need a sound knowledge of nutrition to operate a successful feedlot. Financially, it is important to minimise feed costs, yet optimise liveweight gain and maximise feed conversion efficiency. Liveweight gain and feed conversion efficiency depend on the feed intake and nutrient content of the feedlot diet.

They need to ensure feed ingredients are free of residues by obtaining and keeping details on crop/feed treatments, and checking new feed ingredients according to a written QA manual. Previously used products may no longer be suitable for feedlot diets (for example, meatmeal is BANNED).

Grains

Grains are high in metabolisable energy (ME) (about 13MJ/kg) and crude protein (CP) ranges from 7% to 16%. They promote high liveweight gain and feed conversion efficiency and are fed after processing – dry rolling, hammer-milling or more sophisticated treatments (for example, ‘wet’ processing). Care is needed when feeding grains as they can cause grain poisoning (acidosis), even when changing from one grain to another.

Sorghum

Grain sorghum is a common Queensland feedlot grain. It usually has lower ME and CP than other grains. The digestibility increases by rolling, but increases markedly by ‘wet’ processing (steam flaking, reconstitution). Sorghum grain is ideal for cattle for the Japanese market because it promotes pearly white fat with ideal texture.

Maize

Maize is an excellent feedlot grain, but is not as widely grown in Queensland as sorghum, barley and wheat. Maize is usually more expensive than other grains. Efficiency of use increases by rolling and even further by ‘wet’ processing. Maize has a high ME (13.5MJ/kg), but low CP content. Hominy (a maize by-product) can be used as a maize replacement in diets if it is price competitive to alternative commodities.

Wheat

Wheat CP ranges from 7% to 15% and ME is relatively high. When the price is competitive due to weather effects increasing the amounts of feed quality wheat it is an alternative feedlot grain. Wheat is readily fermented in the rumen which increases the risk of acidosis. High proportions of wheat in the diet can cause digestive upsets so wheat is not fed at more than 50% of the total grain portion. Wheat is usually fed rolled.

Barley

Barley is widely grown in Queensland with low protein barley for the malting industry and high protein barley being suitable for feedlotting. Barley can be fed either rolled, hammer-milled or steam flaked, and has a high fibre content and is safer to feed than wheat.

Triticale, oats and legume grains

Triticale is a minor stockfeed grain in Queensland. It is not as palatable as other grains, but when blended with the other grains is a satisfactory feedlot feed. Oats is not usually used as a feedlot grain. Soybean, chickpeas, mung beans and other legume grains are sometimes fed in feedlot diets up to 15% of the diet. They have high ME and CP levels and may cause bloat.

Bran and pollard

Half the grain component of rations can be substituted by bran or pollard without reducing liveweight gains.

Silage, haylage and ‘green chop’

A range of crops can be stored as silage and haylage including maize, sorghum, winter cereals and legumes. The main difference between silage and haylage is in dry matter (DM) content with silage 35% DM and haylage 50% DM. Silage is stored in the absence of air usually in horizontal bunkers below or above ground level.

Silage and haylage are also stored as plastic wrapped round bales.

With maize, ME is maximised by ensuring that the crop has a good grain yield at cutting – up to 50% of total DM. Good maize silage and haylage have a relatively high ME (10MJ/kg) and CP levels about 8%. The dual purpose, ‘graze or grain’ sorghum varieties make good silage. The low grain yielding leafy forage sorghums need to be cut pre-flowering to maximise ME (9.5MJ/kg) and CP.

Lucerne silage and haylage have low ME (9.5MJ/kg) but good CP levels (19%).

Care is required with ‘green chop’ as more than 20% in the diet can cause yellow fat.

Roughages

Roughages serve to maintain the health and function of the rumen but have a low nutrient content. They are processed to a coarse particle size (about 2cm) to aid mixing and stability of the ration. Roughages are important for introducing cattle to grain. Starting diets usually have about 60 to 80% roughage and 20 to 40% grain plus additives. Commercial feedlotters tend to feed roughage with grain and additives in open troughs. Opportunity feedlotters usually feed in self feeders which reduces the feeding frequency and feeding costs. In some cases, grain plus additives are fed in the self feeder and the roughage is fed separately and unprocessed in hay racks.

Sorghum and winter cereal hays

Sorghum hay is a popular feedlot roughage. It has a high yield per hectare, is palatable and ideal for the starting diet where cattle go from a high roughage to a high grain diet. The quality of sorghum hay depends largely on the stage of maturity at cutting. Winter cereals have a similar quality and features as for the sorghums.

Sorghum and winter cereal stubbles

Sorghum harvest stubbles are a low quality roughage (5 to 7MJ/kg). It is a good roughage for cattle on high grain, high performance diets but not for starter diets because of poor palatability. Winter cereal stubbles are similar to sorghum.

Legume hay and stubbles

Legumes make excellent quality hay with good CP levels (for example: lucerne, lab lab, medics). Legume stubbles tend to have lower CP and ME levels (for example, cowpeas, mung beans, soybeans). Caution should be taken to control potential bloat problems when legume hay is fed with grain.

Cottonseed by-products

Valuable by-products of the cotton fibre industry are whole cottonseed, vegetable protein meal, and hulls. The availability and price of cotton seed depends on the size of the cotton crop and the amount used for oil extraction. It has become sought after by feedlotters since the value of cottonseed became appreciated. The nutrient content is similar to legume grains and it is fed up to 15% of the diet without processing. Sources are the cotton gins, commercial feed and seed companies or by arranging grower contracts. Hulls are low in nutrients but are a good roughage.

DO NOT FEED COTTON TRASH DUE TO THE RISK OF CHEMICAL RESIDUES.

Molasses and tallow

Sugarcane molasses is readily available in Queensland and is a valuable feedlot dietry ingredient. It has a high ME (11.5MJ/kg) and low CP (3%) on a dry matter basis and supplies sulphur and potassium. Molasses is palatable and is added to diets up to 10% to maximise feed intake and reduce dust. Molasses with additives is also available to feedlotters to add to diets.

Tallow is a rich source of energy, reduces dust and is fed up to 3% of the diet. Both of these can be difficult to handle in the feedlot situation.

Vegetable protein meals

Vegetable protein meals supply additional protein, especially for young cattle which require a higher protein diet than older cattle. Vegetable protein meals are derived from plant material only. Vegetable protein meals include cottonseed meal, soybean meal, sunflower meal, linseed meal, peanut meal, copra meal, and palm kernel. Since 10 August 2001 it is illegal to feed animal matter or animal contaminated matter to stock (ruminants, such as cattle, sheep, goats and deer). This includes any meals rendered from animals, such as meat and bone meal, blood meal and fishmeal. Animal rendered products, however, can still be fed to non-ruminant animals such as horses, poultry and pigs.

Urea

Non-protein nitrogen sources like urea are important additives to feedlot diets and supply low cost soluble nitrogen to the rumen. Urea is the most common and richest source of nitrogen although sulphate of ammonia also supplies non-protein nitrogen and sulphur. The rule of thumb is non-protein nitrogen sources make up not more than one third of dietary protein and that urea should not be added at more than 1%.

Limestone

Grains are quite low in calcium, so limestone (37% calcium) is an important addition to feedlot diets. The aim is to maintain the balance of calcium to phosphorus between 1:1 to 2:1.

Phosphorus sources

Most grains are high in phosphorus content but it is used inefficiently by cattle. So high grain, high performance diets require the addition of some phosphorus. Satisfactory sources of phosphorus are dicalcium phosphate (DCP), Kynofos™ 21, Biofos®, monocalcium phosphate (MCP) or tricalcium phosphate (TCP). These products supply both phosphorus and calcium with a content between 15 to 22% phosphorus and 18 to 31% calcium.

Muriate of potash (potassium chloride)

Similarly, muriate of potash may need to be added to meet potassium requirements.

Buffers

Sodium or calcium bentonite is fed as a weak buffer to cattle on grain based diets. Bentonite also firms the consistency of dung. It may be fed throughout or just in the introductory stages of feeding. The feeding rate ranges from 2–4% of the ration. Stronger buffers like sodium bicarbonate are also used in grain based diets to reduce the incidence of acidosis, mainly when cattle are sensitive to higher grain content diets and have acute reactions (scouring, lameness).

Common salt

In some instances it is necessary to add 0.1% to 0.5% salt to feedlot diets to meet sodium requirements unless cattle have access to salt in bore water.

Trace minerals/vitamin premixes

These mixes are generally made up commercially and added at about 0.1% to meet the requirements for micronutrients (magnesium, chlorine, copper, iron, cobalt, selenium, iodine, zinc, manganese) and vitamins (vitamin A and vitamin E). Follow the manufacturer’s instructions for use or precautions in mixing.

Antibiotics

The important group of antibiotics from a feed point of view are the rumen modifiers monensin, lasalocid and virginiamycin. These rumen modifiers modify rumen fermentation patterns to increase the efficiency of feed use and animal health. Some have anti-bloat and anti-coccidial effects. Tylosin is registered for use in Queensland feedlot diets at non-therapeutic levels. At these lower levels it promotes growth and reduces the incidence of liver abscesses. Antibiotics used in human medicine cannot be used as additives to cattle feeds except on veterinary advice and prescription.

Complete commercial diets

A number of commercial feed companies will mill, mix, and deliver complete feedlot diets to your self feeder at the feedlot.

Contaminants

Important feed contaminants are microbial toxins (bacterial and fungal), pesticides and toxic plants or seeds. Bacterial toxins (for example, botulism) arise from dead animals in feed supplies. Fungal toxins or mould (for example, aflatoxins on peanuts) can be minimised by effective storage systems for hay, meal and silage. Care should be taken with grain storage and crop pesticides to minimise contamination of feeds. Ideally, field crop hygiene should prevent toxic plants and seeds finding their way into feeds (for example, thornapple – Datura stramonium).

Further information

Contact the Department of Agriculture and Fisheries Customer Service Centre on 13 25 23 (Queensland residents) or 07 3404 6999 (non-Queensland residents) between 8 am and 6 pm weekdays, or email callweb@daf.qld.gov.au.