April 2013 - AFMA

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Figure 1: Fluorescence microscopy showing that both the aleurone and starchy endosperm cell walls were degraded after three hours of treatment with xylanase (Le et al., 2013). a Table 1: The pure feed protease degrades ANFs more effectively than endogenous trypsin. Recently, refined fluorescence microscopy techniques used for the visualisation of xylanase action on milled wheat and corn indicated that both starchy endosperm and aleurone cell walls are broken down by a commercially available pure xylanase. Such techniques increase the likelihood for future prediction of the solubilisation of the insoluble NSP fraction, thereby also explaining the effect that xylanase and its combination with phytase has on non-viscous cereals such as corn and sorghum. The full economic benefit of these enzymes can only be realised if the energy and amino acid contribution in total is taken into account (Kleyn, 2013). As an example, Figure 1 showed that both the aleurone and starchy endosperm cell walls were degraded after three hours of treatment with xylanase, allowing the release of encapsulated nutrients (Le et al., 2013). Effect of lectins Variability within soybean meals with regards to the content trypsin inhibitors and lectin in the final meal is known, but seldom accounted for in diet formulation. Kunitz trypsin inhibitor (KTI) and Bowman-Birk (BBI) and lectins are important anti-nutritional proteins in soy. Commercial soybean meals are toasted to reduce the effect of these heat-labile components. However, the heat treatment in the toasting process is a compromise between inactivating the trypsin inhibitors and obtaining high protein solubility, hence commercial soybean meals differ significantly in level of e.g. trypsin inhibitors. This can influence the potential performance of a specific feed by indirect and direct effect on the animal (De Coca-Sinova et al., 2008). KTI and BBI both pose a challenge to the pancreas and may cause reduced protein digestibility. Lectin causes irritation of epithelial tissue by binding carbohydratecontaining molecules on the epithelial cells, thereby challenging the immune system. The ANFs also constitutes an important part of the amino acids in soybean meals in that BBI accounts for ~50% of the cysteine pool, critically important when keeping in mind that in soy, sulphurous amino acids (cysteine and methionine) are growthlimiting factors in poultry diets (Vollmann et al., 2003). The potential of a commercial pure feed protease to degrade the trypsin inhibitors and lectin in a soybean meal, as well as its ability to degrade different qualities of soy, was investigated in in vitro studies. An understanding of the effect of an exogenous protease on the most important ANFs in soy makes it possible to more accurately predict the efficacy of such an enzyme to the feed. The studies showed that the pure feed protease was able to degrade lectin, KTI and BBI inhibitors to a large extent (Table 1). A substantially lower degradation was detectable by pancreatic trypsin. Furthermore, in the presence of a commercial dose of this pure feed protease, the same degree of protein hydrolysis was obtained with only 50% of the equivalent pancreatic protease (Figure 2) (Nielsen et al., 2013). 42 AFMA MATRIX ● APRIL 2013
Figure 2: Addition of the pure feed protease enhances the efficacy of endogenous pancreatic protease (trypsin and chymotrypsin) about two-fold. By the degradation of the trypsin inhibitors and lectin in soy, the feed protease possibly enhances the efficacy of the pancreatic proteases (trypsin and chymotrypsin). The potential in vivo impact is a reduced challenge on the pancreas, better access to sulphur-containing amino acids and less stress on the immune system in general, thereby reducing the sensitivity of animal performance to a low quality soybean meal. However, the exact magnitude of the contribution of enzyme is highly dependent on the interaction with other feed enzymes and the interaction of other feed ingredients on each other and on the exogenous enzyme. Other studies demonstrated that this pure feed protease did not influence negatively the efficacy of phytase. On the contrary, an overall positive effect on phytate degradation was observed when feed protease was added together with different phytases. It was also shown that this pure feed protease did not influence the efficacy of xylanases. The feed protease can therefore be added to the diet to specifically attack the protein fraction, while simultaneously using a phytase and a xylanase to degrade phytate and the NSPs fraction (Pontoppidan et al., 2012). Conclusive thoughts Enzymes are highly specific and decades of research are contributing to a better understanding of the substrates they are targeting. The choice of commercial feed enzymes must be made based on the best knowledge available, not only on the enzyme activity itself, but on the substrate it is targeting. Studies on ANFs in feed ingredients provide a better understanding of the mode of action of specific feed enzymes. It is also the key in predicting the nutritional contribution a single enzyme or a combination of enzymes can make to the value of a diet. Estimating the nutritional contribution of an enzyme is a complex task and confounded by the interaction of feed ingredients and metabolic dynamics. Although many reports exist that describe the effect of feed enzymes, sufficient information on the combined effects of these enzymes on nutrient utilisation and animal performance is still lacking. The exact effect of phytase, protease and carbohydrate combinations in terms of animal performance can only be evaluated under proper in vivo conditions. Therefore this remains one of the biggest challenges for scientist and commercial nutritionist alike. The full reference list is available upon request. Feed science
Page 1: APRIL 2013 Volume 22 No 1 Matrix Qu
Page 4 and 5: Editor’s note A battling world ec
Page 6 and 7: News & views China doubles corn pur
Page 9: Benchmarking is a crucial aspect of
Page 13: Feed industry Feed outlook for 2013
Page 19 and 20: Processing The technical and practi
Page 21: a stress condition and compensate i
Page 25: Biofuel co-products as livestock fe
Page 30 and 31: 28 AFMA MATRIX ● APRIL 2013
Page 33: enal osmotic malfunction and/or dig
Page 37: The way feed is presented will affe
Page 42 and 43: Lynn Phillips Consulting cc CK 88/2
Page 47: Control of E. coli, Salmonella and
Page 50 and 51: The impact of amino acid formulatio
Page 52 and 53: Table 2: AMTS recommended carbohydr
Page 55 and 56: Feed science Sow nutrition: Avoidin
Page 57 and 58: ies showed that weight loss had a n
Page 59: of both the advisor and the farmer
Page 62 and 63: Special report: Top feed companies
Page 64 and 65: Table 2: Asian companies in the top

April 2013 - AFMA

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