EFFECT OF THE INTRAMAMMARY DEVICE ON MILK INFECTION STATUS, YIELD, AND SOMATIC-CELL COUNT AND ON THE MORPHOLOGICAL FEATURES OF THE LACTIFEROUS SINUS OF THE BOVINE UDDER

  • 1 January 1983
    • journal article
    • research article
    • Vol. 44  (10) , 1856-1860
Abstract
Twenty primiparous heifers were fitted intramammarily with polyethylene coils in both quarters of 1 random right or left udder half at 5 days after parturition. Foremilk samples were collected and udder-half milk yields measured at the afternoon milking on days -1, 3, 7 and 14, and on every 14th day for 8 mo. after the device was inserted. Three weeks after the heifers were fitted with the intramammary device, 6 were euthanatized for gross observation of devices and tissues, and cytologic evaluation of the gland cistern epithelium. There were significantly fewer bacterial isolations (P < 0.01) and less clinical mastitis (P < 0.05) in treated quarters than in the control quarters. Coagulase-negative staphylococci were isolated at frequencies of 0 and 15.2% for treated and control quarters. The reduction in isolation frequency for treated, compared with control, quarters was less marked with other organisms. Intramammary devices in no way interfered with the milking process. Milk yields per milking were 4.2 kg for treated udder halves compared with 4.4 kg for control halves; this 0.2 kg difference was not significant. Mean milk somatic cell counts, as determined by electronic counter, were 34 .times. 103 and 81 .times. 103 cells/ml for control and treated quarters (P < 0.05). Mean bovine serum albumin values were 0.160 and 0.175 mg/ml for control and treated udder halves (P < 0.05), indicating an increased capillary permeability due to the device. Quantitative morphologic analysis of gland cisterns showed a significant (P < 0.05) change toward a single layer of epithelial cells in treated quarters compared with a double layer in control quarters. Influence of intramammary devices on frequency of new infections probably is multifaceted, involving polymorphonuclear leukocyte migration, blood protein permeability, gland cistern epithelial modifications and other undetermined mechanisms.