Electrophoretic and biochemical comparison of casein and whey protein from porcine colostrum and milk.

Porcine colostrum casein contained at least one major polypeptide band in both acid gel and sodium dodecyl sulfate gel electrophoresis that did not appear in patterns of casein prepared from porcine milk. In sodium dodecyl sulfate gel patterns, this polypeptide possessed a molecular weight of 62,000 and stained positively with "Stains-all" but not with periodic acid-Schiff reagent. Several minor caseins that appeared in acid and alkaline gel patterns from colostrum could not be detected in casein prepared from milk. Seven minor polypeptides in sodium dodecyl sulfate gel patterns of whey proteins prepared from porcine colostrum could not be detected in milk. Identical acid and alkaline gel patterns were obtained for whey proteins prepared from colostrum and milk. Only the sodium dodecyl sulfate gel electrophoretic pattern of casein prepared from milk, and possibly the alkaline gel electrophoretic pattern of whey protein prepared from milk, contained polypeptides not in patterns from colostrum. Total phosphorus contents of colostrum and milk casein were 2.96% and 3.78%. Casein prepared from porcine colostrum contained almost twice as much hexosamine and slightly elevated N-acetylneuraminic acid as casein prepared from milk. Hexose content was nearly equivalent. Whey protein prepared from milk contained more total hexose than casein prepared from colostrum, whereas N-acetylneuraminic acid and hexosamine contents were nearly equivalent.

Epiphytic microflora on alfalfa and whole-plant corn.

Epiphytic microflora were identified and counted on four cuttings of alfalfa, each harvested at three stages of maturity, and on three whole-plant corn hybrids. Enterobacteriaceae were predominant on both crops. Yeasts and molds also were major epiphytic microorganisms on whole-plant corn. The group--including lactobacilli, pediococci, and leuconostocs, which are genera that produce lactic acid and thus are instrumental in silage preservation--constituted only a small proportion of the total population (less than .5%) on both crops. Lactate-fermenting clostridial spores were not detected on standing alfalfa, and occurrences of these spores on standing corn plants were due to soil contamination from rainfall prior to harvest. The numbers of epiphytic microorganisms, except for the lactobacilli, pediococci, and leuconostocs group, were higher on standing corn than on alfalfa. The epiphytic microflora on alfalfa increased with increasing temperature during the growing season. However, neither cutting number nor maturity affected the epiphytic microflora on standing alfalfa, and wilting following mowing had little effect on most populations. Higher temperatures during wilting increased yeast and mold counts but had no effect on other microbial counts. The chopping process tended to increase the epiphytic microflora populations compared with those on the standing crops, and the group containing lactobacilli, pediococci, and leuconostocs was most enhanced. Only yeast and mold counts on the chopped alfalfa increased with greater DM content and buffering capacity.