COMPARATIVE-STUDY OF PROTEINS, PEROXIDASE-ACTIVITY AND N-ACETYL-BETA-D-GLUCOSAMINIDASE ACTIVITY IN LLAMA MILK

Increased rearing of llamas in the USA has been associated with a need to supplement milk to orphaned or undernourished llama neonates. Rumi nant milks and milk replacers are used, but there are few data compari ng the nutrient composition and protective factors of llama milk to th ose of ruminant milks. We compared proteins in llama milk with those i n cow, sheep, and human milks. Proteins were separated by sodium dodec yl sulfate-polyacrylamide gel electrophoresis and visualized by Coomas sie blue. Caseins were the predominant proteins in llama milk, as in c ow and sheep milks. A considerably lower proportion of casein was iden tified in human milk. alpha-lactalbumin was present in similar amounts in llama, sheep, and cow milks, with proportionately more alpha-lacta lbumin in human milk. beta-Lactoglobulin, the major whey protein of co ws and sheep, was not detectable by this method in either llama or hum an milk. Gel profiles of llama milk contained a relatively higher prop ortion of a protein band co-migrating with lactoferrin compared with c ow or sheep milk, but not as much as in human milk. We also compared t he activities of peroxidase and N-acetyl-beta-D-glucosaminidase in mil ks of the four species. Peroxidase activity in llama milk was more tha n ten times less than in cow or sheep milk. Activity of N-acetyl-beta- D-glucosaminidase was more than 20-fold higher in llama milk than in m ilks of the ruminants. Activities of both enzymes in llama milk more c losely resembled activities in human milk. Results of this study sugge st that llama milk differs from cow and sheep milk in protein composit ion, and that the relative importance of protective factors, such as l actoferrin, peroxidase, and N-acetyl-beta-D-glucosaminidase, in milk m ay be different for llamas compared with ruminants.