Biochemical changes of the milk in experimental caprine mastitis induced by Mycoplasma serogroup 11 (2-D)

Biochemical changes of the milk were studied in 7 lactating goats. The right udder halves of the animals were inoculated through the teat canal with 1 ml of Mycoplasma ovine/caprine serogroup 11 (2-D) culture containing 6x10(6) colony forming units ml-1. The left udder halves of these goats were kept as control. The experiment was continued for 35 days during which period one goat was killed every 5th day. All the goats developed clinical mastitis within 24 h and the infected udder halves remained enlarged for 4-5 days. The milk from these halves was yellow-tinged and showed slight separation of proteins. Subsequently, there was marked reduction in the size and secretion of the infected udder halves, followed by agalactia from post-inoculation (PI) day 22. The mycoplasmas were reisolated from milk samples of the infected halves up to PI day 20. Histopathological examination of these halves revealed changes indicative of acute and chronic mastitis. Biochemical analysis of mastitic milk/mammary secretions showed a marked increase in the concentration of total proteins, immunoglobulins, free fatty acids and phospholipids, while the concentration of total lipids and glycerides initially underwent a considerable decrease as compared to the basal and control values. However, the level of total cholesterol decreased sharply during the initial days while later, from PI day 5, it markedly increased. This study shows that Mycoplasma ovine/caprine serogroup 11 is pathogenic to the lactating udder of goats and produces marked biochemical alterations in the milk.