Carotene and immunoglobulin concentrations in the colostrum and milk of pasture-fed cows
Summary The carotene and immunoglobulin concentrations in colostra and milks of 6 Jersey, 4 Friesian and 6 Jersey × Friesian cows were determined during the first 21 d of lactation. Carotene concentrations of between 50 and 300 μg/g milk fat were found at first milking and these declined to normal concentrations, in the range 9–21 μg/g milk fat, by the eighth to tenth day of lactation. Immunoglobulin concentrations at first milking were in the range 4–40 g/l milk and decreased to normal concentrations, in the range 0·3–0·5 g/l, by the fifth to seventh day of lactation. For both substances the data from each cow's milk fitted an exponential decay model. The fractional rates of decrease in concentration of carotene were 0·19–0·57/d and of immunoglobulin were 0·40–0·73/d. Breed-group differences were observed in both carotene and immunoglobulin concentrations in milks after the fourteenth day of lactation. In Jersey milks, the average carotene and immunoglobulin concentrations were respectively 18·5 μg/g milk fat and 0·32 g/l of milk, while in Friesian milks the concentrations were respectively 11·4 μg/g milk fat and 0·46 g/l milk. There was also a difference between breed groups in the daily rates of decrease of the immunoglobulin concentrations. The average rate of decrease for the Friesians was about 1·5 times the rate for the Jerseys.
Colostral immunoglobulin concentrations among breeds of dairy cattle.
Colostral immunoglobulin concentrations were compared among five breeds of dairy cows. Colostrum samples (3 to 4 kg) were obtained immediately after parturition from 19 Ayrshire, 17 Brown Swiss, 12 Guernsey, 19 Holstein, and 5 Jersey cows. Average total colostral immunoglobulin was 8.1, 6.6, 6.3, 5.6, and 9.0% for them. Colostrum from Jerseys had the highest immunoglobulin G (6.65%), immunoglobulin A (1.86%), and immunoglobulin M (.53%) of all breeds. Colostrum from Holsteins was lowest in immunoglobulin G (4.12%) whereas that from Guernseys was lowest in immunoglobulin A (.90%) and immunoglobulin M (.39%). Breeds may differ, and the high calf mortality and health problems frequently reported for Guernseys may be related to the low immunoglobulins A and M in colostrum. Concentration of colostral immunoglobulin by calving number was examined over breeds for 23, 16, 17, and 14 cows by first, second, third, and fourth or later calvings. Colostral immunoglobulin was lower from first-calf heifers (5.68%) than from third (7.91%) and fourth (7.53%) parity cows. Colostral immunoglobulins A and G tended to be lower in first lactations.
Synergistic Effect of High Temperature and High pH on the Destruction of Salmonella enteritidis and Escherichia co1i O157:H7.
This study was undertaken to determine if high temperature and high pH interact synergistically to enhance the rate of destruction of two important gram-negative foodborne pathogens, Escherichia coli O157:H7 and Salmonella enteritidis . The rates of destruction in NaHCO3-NaOH buffers at pH 7.0, 10.0, and 11.0 were determined at 35, 40, 45, 50, 55, 60, and 65°C. Use of an improved heating protocol eliminated a "tailing effect" at longer exposure times. The present study demonstrated that the combination of high pH and high temperature resulted in a highly significant synergistic interaction (P > F = 0.0001), which caused rapid death of both E. coli O157:H7 and S. enteritidis . This "alka-therm" technology might be used commercially to destroy gram-negative foodborne pathogens on various raw agricultural commodities.