Plant proteins can replace animal proteins


Pig Progress 

May 8, 2019   


Nutritionists typically acknowledge animal protein as being a quality, highly digestible feed ingredient that is favoured for addition to diets for young animals. Over the years, however, plant-derived alternatives have emerged which lead to similar performance results.


In the past, fishmeal inclusion rates were considered optimal at around 10% for piglet and broiler feeds. Nowadays, however, most premium piglet feeds may contain only 5% of fishmeal and broiler pre-starter feeds containing any fishmeal are rare, especially when using high-quality products. It is projected that by 2025, fishmeal will be an exception in livestock diets. A similar tendency is probable for other animal protein sources.


In addition, there is often a variation in nutrients. Differences are relatively easy to analyse, but levels of biogenic amines are often hard to determine. Those are biologically active compounds synthesised from amino acids, which are occurring should animal protein be in a state of decomposition. Numerous studies have shown that feed-borne biogenic amines are toxic and cause a poor performance or even death in pigs and poultry.


Apart from these two reasons, another major reason is for the gradual disappearance of animal protein sources is a growing public and political concern about the safety of feeds with animal origin. In recent years, that concern has grown due to e.g. feed-borne bacterial infections, toxic compounds, veterinary drug residues and contamination. Animal protein can be connected with feed safety issues and shows a wide variety in quality. Examples are the possible contamination with ­dioxins, entero-bacteria, salmonella and E. coli.


Add to this the recent concern about the spread of African Swine Fever. At the moment, in some parts of the world, the use of animal products is being discouraged in the context of the virus’ emergence.


Switching to plant-based proteins


Plant-based proteins are a safe, and often cheaper, alternative. However, plant proteins are generally digested not as easily as animal proteins. Undigested protein will serve as a substrate for E. coli and Clostridia. For that reason, reduction of the crude protein content in diets has been applied to improve gut health, as an alternative strategy to using antibiotics. In the Netherlands, piglet weaning diets usually have crude protein levels of 16.5-17.5%.


Secondly, upgrading digestibility of plant protein sources is key to overcome this problem. Protein digestibility is of crucial importance in young animal nutrition. The animal’s performance – growth and efficiency – is largely related to protein levels and ileal digestibility. Standardised ileal digestibility (SID) represents an animal’s efficiency to use this protein source for growth, with close to 100% being very efficient. In short, a higher digestibility is desired, as that will induce growth, but also limits growth of harmful bacteria, reducing the incidence of diarrhoea – and as a result, antibiotic use.


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Comparison with others ...


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