Californian Mastitis Test Research Articles

Free and total GMP (glycomacropeptide) contents of milk during bovine lactation

Individual milk samples taken every two weeks from parturition to the end of lactation from 34 animals of three different herds and breeds were analyzed for free-GMP. A milk pool of each herd was analyzed for free and total GMP (released from k-casein by the action of rennin) and the data were correlated with sanitary conditions of animal and udder, phase of lactation and milk production. Most udder problems were concentrated near parturition, with few and spaced occurrences of clinical mastitis. The Californian Mastitis Test (CMT) results showed oscillations compatible with the phases of lactation period and environmental conditions. The widest variations in free-GMP occurred as a function of lactation period and as a consequence of clinical or subclinical mastitis. Higher levels were observed at the beginning of lactation (5.87mg L-1 of sialic acid), becoming normal with mean values of about 3.30mg L-1 at the end of the second month, and increasing again during the final third of lactation. On average, the same trends were observed for total GMP released by commercial rennet, beginning with slightly high values (35.59mg L-1), becoming normal by the sixth month with values close to 27.15mg L-1, and rising gradually up to the end of lactation, with 58.35mg L-1 of sialic acid. These results prove to be useful for the correct interpretation of tests applied to milk selection with respect to proteolytic status or even to restrain frauds by the addition of whey to milk.

Concentrations of triiodothyronine (T3), tumour necrosis factor-α (TNF -α) and interleukin-6 (IL -6) in milk from healthy and naturally infected quarters of cows

The effect of naturally acquired bacterial infection of the bovine udder on the activity of 5′-thyroxine monodeiodinase (5′- MD), and on the concentrations of the pro-inflammatory cytokines interleukin(IL) -6 and tumour necrosis factor (TNF) -α in milk, from healthy (control) and inflamed quarters, was determined. The diagnostic procedure included history and clinical examination of the udder, macroscopic evaluation of secretions, the Californian Mastitis Test, determination of somatic cell counts and bacteriological examination of milk. It has been found that the milk triiodothyronine (T3) content and the 5′- MD activity from inflamed quarters were decreased when compared with controls. The decrease in the milk T3 from subclinical mastitic quarters was manifested when somatic cell counts were >106ml−1. TNF -α was on average 2-fold higher in infected milk, and the concentration of IL -6 was unchanged. These results suggest that the decreased T3 content in mammary secretions during naturally occurring mastitis is associated with the severity of inflammation, increased TNF -α concentration and impaired enzymatic activity of 5′- MD.

The detection of subclinical mastitis in the bactrian camel (Camelus bactrianus) by somatic cell count and California mastitis test

Milk samples (n = 160) from 7 clinically healthy bactrian camels were cultured to detect subclinical udder infection. The samples were assessed by the Californian mastitis test (CMT) and somatic cell count (SCC). Bacteria were recovered from 36 (22.5%) of the milk samples. Staphylococcus aureus and coagulase-negative staphylococci (CNS) were the main organisms found. Infected quarters had significantly higher mean values for the SCC (p < 0.01) and CMT (p < 0.001) than non-infected quarters. All 7 camels were infected with CNS but only 4 with S. aureus. CMT values for S. aureus-infected camels were significantly higher than for those only infected with CNS. The values for SCC and CMT were significantly influenced by the stage of lactation (p < 0.05). No significant difference was found from the effect of the quarters. Both SCC and CMT were of value in predicting the infection status of the udder.