Protein nutrition species differences

The sacroplasmic proteins myoglobin and hemoglobin are responsible for much of the color in meat. Species vary tremendously in the amount of sacroplasmic proteins within skeletal muscle with catde, sheep, pigs, and poultry Hsted in declining order of sarcoplasmic protein content. Fat is also an important component of meat products. The amount of fat in a portion of meat varies depending on the species, anatomy, and state of nutrition of the animal. The properties of processed meat products are greatiy dependent on the properties of the fat included. Certain species, such as sheep, have a relatively higher proportion of saturated fat, whereas other species, such as poultry, have a relatively lower proportion of saturated fat. It is well known that the characteristic davors of meat from different species are in part determined by their fat composition. 

The ratio of casein whey proteins shows large interspecies differences in human milk, the ratio is c. 40 60, in equine (mare s) milk it is 50 50 while in the milks of the cow, goat, sheep and buffalo it is c. 80 20. Presumably, these differences reflect the nutritional and physiological requirements of the young of these species. 

The effects of HS on ion uptake appear to be more or less variable and selective, depending on the HS involved, their concentration, the plant species, and the composition and pH of the medium. Studies on uptake kinetics, use of protein synthesis inhibitors and different experimental conditions suggest that the effect of HS on plant nutrition may be mediated by modulation of the synthesis and functionality of membrane proteins. 

As mentioned in section 4.1, milk is species-specific, designed to meet the nutritional and physiological requirements of the young of that species. There are about 4300 species of mammal but the milks of only about 170 have been analysed, and data for only about 40 of these are considered reliable. Not surprisingly, human and bovine milks have been studied most intensely. In many respects, the milks of these two species are at the opposite ends of a spectrum. It will be apparent from the foregoing discussion that the proteins in human and bovine milks differ markedly, both qualitatively and quantitatively. Some of the more important differences are summarized in Table 4.8. At least some of these differences are probably nutritionally and physiologically important. It is perhaps ironic that human babies are the least likely of all species to receive the milk intended for them. 

The application of these methods has resulted in the isolation of a large number of strains, many of which appear to be taxonomically identical. However, at least a dozen different types do exist which deserve to be delineated as separate species. It should be mentioned that taxonomic identity does not exclude minor differences in qualities which may be important for the production of biomass of nutritive value, e.g. growth rate, content of lipids, nucleic acids and lipopoly-saccharides, protein quality etc. 

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