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Lotfed or intensively finished animals require a balanced ration that supplies all their nutritional requirements if they are to realise their full growth potential. To maximise production in the feedlot and intensive finishing environment, an understanding of ruminant livestock feed requirements and feed nutritive value is important.
The nutritional requirements of cattle, sheep and goats reflect the requirements of the microbes that occupy their rumens. These microbes breakdown feed into volatile fatty acids which are used by the animal as energy for body function and growth. They also pass into the small intestine where they are absorbed and form the main source of protein for the animal.
Good livestock production relies on a healthy and stable population of rumen microbes. Feedlot and intensive finishing nutrition is as much about feeding rumen microbes as feeding the animal.
The population of microbes in the rumen includes fungi, bacteria and protozoa, all of which fulfil a different function, from utilising starch through to breaking down fibre. These microbes thrive in different parts of the rumen including within a fibrous mat made up of dietary roughage. This mat and the resident microbes need to be maintained to allow other important components of a feed ration, such as grain, to be fully utilised and for good animal health to be maintained.
Feedlot and intensive finishing rations are formulated to maximise weight gain to meet market specification while maintaining good animal health. This is achieved by providing a ration with the highest energy content that can be safely fed while still supporting rumen microbes that rely on roughage. The components contributing to energy can be as much as 85% of the ration, with grain being the main component.
Animals are introduced to feedlot or intensive finishing rations gradually by feeding decreasing amounts of roughage and increasing amounts of grain over the initial 15-20 days. This allows the level microbes in the rumen to adjust gradually and minimises the risk of adverse responses, such as rumen acidosis, which can occur when ruminants are fed too much grain and too little roughage.
The fundamental components of a feedlot or intensive finishing ration are protein, energy, roughage and minerals. These are usually fed as a total mixed ration several times per day. A good supply of water is also important.
The protein in the ration is usually supplied as a protein meal and may be supplemented with non-protein nitrogen. Rather than "feeding" the animal, these inputs do more to feed the microbes which in turn pass from the rumen to the small intestine where they are absorbed and make up more than 70% of dietary protein.
Ration energy allows rumen microbes to grow and multiply and provide energy to the animal. Energy is typically supplied as or derived from cereal grains (processed in some way to improve digestibility), silage, molasses and by-products, such as citrus pulp and whole cotton seed.
Roughage or fibre is important to maintaining rumen microbial balance, especially when high-energy rations are being fed. Roughage is usually provided as hay in a total mixed ration and it is advisable that individual particle lengths be at least 5cm long.
A range of minerals are important to maintaining good rumen function and animal health and welfare in the feedlot and intensive finishing environment. Minerals such as calcium, phosphorus, magnesium and sulphur are included in the total mixed ration.
Rumen buffers can be added to a total ration mix to improve rumen function. Sodium bicarbonate acts to neutralise acid and reduce the incidence of acidosis when feeding high grain diets. Feeding bentonite is thought to increase the flow of microbial (protozoal) protein from the rumen to the intestines leading to increased production.
Rumen modifiers such as monensin, tylosin, virginiamycin, bambermycin and lasalocid may be included in a ration to positively influence the microbial balance in the rumen and achieve production benefits.
Hormone growth promotants
Hormone growth promotants (HGP) are based on naturally occurring male or female growth hormones and stimulate growth and improve feed conversion in cattle to above normal production levels. These come in the form of implants which have a "pay out" or effective period usually of 100 or 200 days, depending on the product used.
Once an implant has been applied, it remains with the animal permanently and can be detected beneath the skin, even after the hormone has been completely depleted. The use of HGPs must be declared on the Livestock Production Assurance National Vendor Declaration and Waybill (LPA NVD/Waybill).
Growth promotants can affect eating quality, however, these effects can be managed utilising various Meat Standards Australia (MSA) pathways such as ageing and tenderstretching. HGP treated cattle are eligible for MSA.
The use of hormone growth promotants in the feedlot environment will depend upon the market specifications of target markets.
Nutritional deficiencies are rare where well planned rations are fed during lot feeding and intensive finishing, particularly in short fed situations. Rations should consist of sufficient protein, energy, roughage and minerals to maintain rumen function and support livestock growth to meet market specifications.
Minerals of particular importance to livestock growth are calcium and phosphorus and these may be supplied as individual components of a total mixed ration.
Livestock health should be monitored on a daily basis and any animal health issues thought to be linked to nutrition brought to the attention of the feedlot nutritionist or veterinarian.
Withholding periods and export slaughter intervals
Feedlot operators and intensive finishers must not only ensure that all withholding periods (WHP) and export slaughter intervals (ESI) are observed for the chemical treatments they use on their livestock, but they must also ensure that the feedstuffs they use are free from all residues.
All commodity feed stuffs bought in should be accompanied by a fully completed Commodity Vendor Declaration (CVD), Fodder Vendor Declaration or By-product Vendor Declaration.