Animal ingredients to enhance a healthy gut
To a large extent, poultry diets are usually based on ingredients from plant origin. Also animal ingredients like proteins and fats are a useful source however. These can play an important role in formulating a qualitative and balanced feed.
By Ronald Mors, Morsvit Feed Consultancy and Louis Van Deun, Sonac (Darling Ingredients International)
Qualitative and balanced nutrition often is the basis of proper management in dealing with coccidiosis and other diseases. The digestive tract of the young animal is in full development and prone to pathogens. Care should be taken in supplying the pullet with palatable, concentrated and digestible nutrients to support a healthy growth. Feed ingredients of animal origin offer great value when taking into account these parameters. Well-known products like hemoglobin powder and animal fats have since long been appreciated for their concentrated nature and high biological value. As such, they offer the nutritionist added flexibility when formulating. Next to these nutritional classics, during the past years a new generation of carefully processed animal proteins such as mucosal peptones and plasma has been developed, coupling nutritional value to added functionality. These ingredients often show added value during the first, fragile weeks of growth of the new-born animal, laying a sound base for improved technical performance during later stages in its life cycle.
Pure, digestible protein
Hemoglobin powder or red cells are a product of blood fractioning. Because of its origin, a typical hemoglobin powder will contain +90% of protein or almost 100% based on dry matter. The quality of the protein is very high: Almost 50% of the amino acid profile is formed by essential amino acids – which is quite typical for ingredients of animal origin. Most interestingly hemoglobin is dried in a controlled spray-drying process, avoiding burning and deterioration of the protein quality. Digestibility trials show in-vivo digestibility values of 95% for individual amino acids. Offering the animal highly digestible protein sources is a well-known factor in avoiding unwanted microbial growth in the gut. Finally, hemoglobin powders supports litter quality thanks to its low ratio potassium/crude protein, an agent which is possibly linked to wet litter.
When formulating hemoglobin in broiler diets, the first limiting amino acid is isoleucine. Various broiler trials (Lessire, 1996; Irta Spain, 2009) have shown that inclusion levels below 3% show no effects of growth limitation or feed conversion efficiency. Other trials (Frugé, 2006) show enhanced performance, especially when compensation is made for isoleucine and possibly arginine. Literature (Figure 1) and daily practice indicate an inclusion optimum between 0.5 and 1%.
Animal fats vs vegetable oils
Table 1 lists some classical fats and oils commonly used in broiler feeds. Comparing fatty acid profiles, animal fats are known to contain more saturated fatty acids then vegetable oils (but not palm oil). This is associated with a higher melting point and a lower energy density. Poultry fat offers the best of both worlds and is popular in broiler and turkey feeds. Poultry fat is characterised by excellent digestibility and has a high metabolic energy (ME) value, rated equal to soy oil. This can be explained because of the linoleic acid (C 18:2) content of about 20% whilst relatively high fatty acid fractions of oleic acid (C 18:1) and palmitic acid (C 16:0) help to maintain a good carcass and meat quality. If carcass quality is at stake (‘dripping’) pork fat or lard can be an option as these saturated fats have higher melting points. If fed to birds in adequate amounts (up to 6%) also the melting point of body fat (adipose tissue under the skin) increases.
Pre-digested concentrated protein
Animal protein hydrolysates are characterised by their small average molecular size. During processing they are submitted to a hydrolysation step cutting up big protein molecules into smaller particles. Porcine peptones or peptides obtained from intestinal tissue are a relatively common product, with a typical average molecular size no greater than 500 Dalton or 3 amino acids. Crude protein contents range from 60-90% depending on further processing steps such as desalination which concentrate the protein level. Trials have been performed mainly on piglets, showing improved feed conversion efficiency in the first week after weaning. Literature states small molecular peptides are very efficiently and rapidly absorbed by gut cells (enterocytes) in all species. Freshly hatched pullets with developing enzymatic functionality can efficiently metabolise these low molecular weight peptides. This supports the proper evolution of enterocytes and gut villi, ensuring gut barrier integrity.
Table 2 shows results from a broiler trial performed by the University of Madrid at Coren Foundation test facilities (2012) in which a concentrated peptone was compared to soy meal and fish meal focusing on the first two weeks of growth. At 3% inclusion, especially in the first phase the benefit of mucosal peptone became evident as the FCR significantly decreased by 3 points and outperformed the other protein sources.
Immunoglobulins from animal plasma
Animal plasma is derived from porcine (or bovine, outside of EU) blood. After collection at the slaughterhouse from approved and inspected healthy animals, the plasma fraction is separated from the blood by centrifugation. After a concentration step the plasma is spray-dried and sold as a creamy-white powder. For two decades the beneficial effects of plasma in young piglets have been well documented: enhanced feed intake, improved weight gain and more efficient feed conversion observed especially in the first week post-weaning. The highly functional ingredient has a positive effect on gut health, can bind to pathogens thanks to its immunoglobulin (IgG) component and can modulate a strong pro-inflammatory immune response after infection or artificially imposed antigen challenge. Effects are maximised in sub-optimal hygienic conditions. Research on plasma performance in poultry is limited but similar effects can be expected based on the suspected modes of action.
Recently the University of New England Australia published a trial performed on broilers in which the addition of 0.5% or 1% of bovine or porcine plasma was tested. During the first 10 days pullets were fed diets containing 0 to 1% of plasma powder. Next, all groups switched to a commercial diet and were monitored for a total of 35 days. Feed conversion rate (FCR) of groups fed with plasma improved several points during the first 10 days. More importantly the positive effects on FCR were maintained during the complete trial period of 35 days (Figure 2), even when all trial groups shared the same commercial diet for the remaining 25 days. From this trial can be understood that an inclusion of 0.5% of either porcine or bovine plasma to a broiler starter diet can reduce the feed conversion ratio by 10 to 14 points as obtained over the total growth period of 35 days.
Biological value
Animal ingredients offer the poultry nutritionist excellent options to formulate concentrated diets with high biological value. A new generation of functional animal proteins boost the health and the performance of young pullets through multiple mechanisms. Functional animal proteins focus on gut health by enhancing feed intake, offering balanced amino acid profiles, providing highly digestible sources of protein and/or stimulating passive immunity in the intestinal lumen.
References are available from the authors – rm@morsvit.nl / louisvandeun@sonac.biz
[Source: World Poultry – Managing Coccidiosis, 2014]
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