In this series about the raw materials used in Denkamilk products we will explain a number of aspects in detail. The previous article on the raw materials in calf milk replacers covered different dairy products. This article focuses on vegetable proteins.

Background

The inclusion of vegetable protein sources in calf milk replacers arose at a time when dairy products were expensive and the price of calf milk was under pressure. Proteins from vegetable sources were economically interesting and increasingly available. Vegetable protein is not found naturally in milk so a lot of research was carried out at our DenkaFarm Innovation Centre to find the right sources and prerequisites for a successful application.

Research is essential

Thanks to digestibility trials carried out at our farm we can determine the digestibility of raw materials and thus determine the value of a product.

Before a new protein source can be used in milk for calves, as well as for kid goats and lambs, it is first extensively tested in the laboratory. We test properties such as solubility and stability and check for the presence of various anti-nutritional factors (ANF) before we do research on the animals. ANFs are substances in plants that protect it, for example, from insect attack, but they often have a negative effect on digestion and the health of the animal. Examples of ANFs are trypsin inhibitors and tannins (bitter substances). We do not want to introduce these types of substances to our young animals whose digestive systems are still very sensitive. That’s why all raw materials are intensively checked for these ANFs before they are used. In this way we ensure that the vegetable-based raw materials used in our milks are completely safe.

After the raw material has been approved in the laboratory, we carry out digestibility trials in our research centre. Here we establish the digestibility of the raw material in order to determine the value of the product. With this information we can calculate the correct inclusion level of the new protein in the diet and we know if there are any limits to its digestibility.

Wheat gluten

Several vegetable-based raw materials are frequently encountered in calf milks. One of these is wheat protein or wheat gluten. Wheat protein was originally a by-product of wheat starch extraction and it contains a high proportion of protein, more than 80%. In addition, it is a very safe product because it does not contain ANFs. However, there is one condition when using wheat gluten in calf milk: it should be hydrolysed. Hydrolysis is a process in which the proteins are enzymatically cut into smaller pieces, so somewhat pre-digested. If this step is not applied to wheat gluten then the raw material is poorly soluble which of course is not practical for a calf milk replacer. Figure 1 shows the difference in solubility with or without hydrolysis.

Soya protein concentrate

Figure 1. The effect of hydrolysis on the solubility of wheat gluten.

Another common vegetable protein source in milks for calves and lambs is soya protein concentrate or SPC. Soya protein concentrate is a by-product of the soyabean oil industry. There is a lot of difference in quality within the group of SPCs and selecting the right source is essential. Several ANFs are naturally occurring in soya, but luckily by means of processing these can be made harmless so that the soya protein can be utilised by the calf or lamb. Our laboratory tests every consignment of SPC as it is delivered for the presence of these ANFs to ensure that we only use the correct quality. SPC also has clear benefits because animals find its taste pleasant and the profile of the essential amino acids is reasonably similar to that of dairy protein, which makes the biological value of the protein high for ruminants.

Pea protein

Pea protein is also a vegetable protein source that we process into a number of products. We use material from a special sort of pea that has been through an extra production step so that it is readily soluble, no longer contains ANFs and is easily digested by the animal. The biggest advantage of pea protein is its flavour. Kid goats in particular find it very tasty.

Quality makes the difference

Whereas the previous article stated that there are many types and qualities of dairy raw materials, the world of vegetable raw materials is probably even larger. In addition to wheat, soya and peas, there are many more possible vegetable protein sources, which might not be used now, but in future will play an important role. However, remember that the quality requirements and preconditions that must be made on these raw materials in order to be correctly applied, are more crucial than for dairy proteins. Nevertheless vegetable protein sources play an important role in the protein component of milk replacers for young animals and offer an opportunity to optimally utilise by-products from other industries.

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