Feed processing - impacts on nutritive value and hygienic status in broiler feeds
Most of the technological processes in compound feed manufacturing impact on nutritive value and hygienic status of the resulting feed and sometimes act synergistically.
The nutritive effect is mainly exerted on feed digestibility and efficiency of energy utilisation. The return on energy invested in feed processing is positive for the majority of processes when balancing against the gain in available feed energy.
In terms of dietary protein (amino acids) and feed additives like vitamins, enzymes and probiotics, special attention must be paid when applying thermal processes. Only a feed/purpose specific selection of treatment processes and fine-tuned process parameter setting brings optimal results in a scenario with sometimes conflicting objectives: maximum improvement of nutritive value combined with optimal decontamination of pathogenic germs.
Whereas an improved nutritional status of the processed feed is durable, precautionary measures must be taken to maintain its hygienic status.
Domestication and breeding of animals has improved animal performance in an unprecedented manner. The requirements in terms of nutrients have increased accordingly. Feedstuffs as offered by nature cannot meet these requirements, without further processing. The coverage of dietary energy needs poses a particular challenge in feed formulation and subsequent manufacture. In the process of making dietary nutrients available for metabolic purposes, the digestion process is a major influencing factor.
Digestive capacities of animals has remained largely unaffected despite centuries of breeding and selection. Therefore, the preparation of feedstuffs before ingestion to improve digestibility became a major focus in nutrition research. On the other hand, the production units for livestock have become larger driven by economy of scale.
This has heightened the importance of hygienic regimes including feed hygiene to prevent disease outbreaks and securing hygiene and feed ingredients of animal origin. This paper highlights some key processing steps in compound feed processing and their impact on nutritive value and hygienic status.
It can be stated that short and long conditioning have very little effect on nutritive value. Grinding and crumbling have no hygienic effect.
Conditioning with subsequent pelleting has some effect while expansion plus pelleting has pronounced effects on both nutritive value and hygienic status. Pelleting agglomerates smaller feed particles with the help of mechanical pressure, moisture and heat to larger particles. This tends to improve animal performance due to less feed wastage, absence of selective feeding, improved palatability and starch gelatinization. Numerous trials have shown better daily gain and feed conversion broiler feeds.
Toasting is reserved for the treatment of single ingredients like soybeans, peas, beans, canola and others. It is used to eliminate or reduce the content of anti-nutritional factors in these ingredients, before they can be used in compound feed.From that angle this process is very significant in terms of improving the nutritional value of these ingredients, which otherwise could be used only with limitations.
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Article made possible through the contribution of the Australian Poultry Science Symposium (APSS) 2006.