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Blood Protein Sources In Milk Replacers |
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The two blood proteins most commonly used in milk replacers are animal blood cells and animal plasma. Milk replacers containing these proteins would list either Spray Dried Animal Blood Cells or Animal Plasma within the first two lines of the ingredient list on the product tag or label. As shown in the figure below, whole blood is separated into these two distinct blood components through the process of centrifuging.
Spray dried animal plasma provides unique animal proteins containing globulin and albumin proteins. A typical analysis shows that animal plasma provides between 70-78% crude protein and contains about 23% IgG and 48% albumin protein fractions. This highly soluble, high quality protein source has an amino acid profile and nutritive value comparable to nonfat dried (skim) milk and casein. Animal plasma protein is substituted for a portion of milk protein in milk replacers to provide additional benefits to the animal rather than to reduce cost. Calves receiving milk replacer with animal plasma perform either equal to or better than calves receiving an all milk protein milk replacer, and often show greater starter consumption. The level of improved performance appears to be related on farm conditions, with better responses observed in calves undergoing greater challenges. 
These responses may be due to the non-nutritive effects of animal plasma in addition to its being a highly digestible and nutritious feed source. Animal plasma has been shown to increase the size of villi in the small intestine. Larger villi mean an increased capacity to absorb nutrients. Furthermore, animal plasma has been shown to have an effect on the immune system by reducing activation. Activation results in decreased feed intake and energy efficiency since more energy is channeled toward body defenses. Whether the effect is direct, whereby pathogens are prevented from attaching and growing in the small intestine, or indirect through improved intestinal growth and pathogen barrier function, reducing immune system activation frees energy to be used of growth rather than body defenses. Animal blood cells are a combination of both red and while blood cells. Due to their favorable amino acid profile and high digestibility, spray dried animal blood cells can be substituted for a portion of milk protein in high quality milk replacers. Research studies show comparable performance between calves receiving milk replacer with animal blood cells and those receiving an all milk protein milk replacer. Although the inclusion rate of animal blood cells is limited, a sufficient amount of blood cells can be substituted into milk replacer to reduce ingredient cost, lowering product price. |
