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A total number of 36 cross bred jersey cows with external teat injury without involving the teat cistern and with exposed teat sinus were subjected for the present study. Clinical examination of teat for its shape, length, distance from the ground and etiology of the teat wounds were recorded. Following preoperative evaluation, the animals were divided into Group I with 12 animals and treatment group with 24 animals each. Group I were treated with Povidone iodine solution. In treatment (Group II), after suturing the wound was protected with sheets of collagen and calcium alginate as protectants. The application of collagen based teat protectant is an effective methodology for favoring healing process of external injuries when compared to the conventional antiseptic drugs using Povidone iodine.

SummaryFour studies are described of the role of friction in maintaining the teatcup stable on the teat. Measurements of the coefficient of friction between teats and pieces of liners, in which most values for the coefficient fell between 0·5 and 1·0, indicated that friction between skin and rubber-like materials was consistent with the general frictional behaviour of elastic solids. Studies during milking showed that the sudden restriction of milk flow that normally occurs near the end of milking is accompanied by a marked fall in the frictional force between the teat and barrel of the open liner. During the period of peak milk flow-rate, the major source of friction maintaining the teatcup stable on the teat is the large area of contact between the teat and liner barrel. The frictional force is derived from the pressure difference across the teat wall which presses the teat against the comparatively rigid liner. Frictional force between the teat and barrel increases after the start of milking because the coefficient of friction rises as one surface gradually moulds to the other. In addition, the total frictional force increases because of the increasing area of contact whenever the teat moves deeper into the liner, until the end of the peak flow-rate period. When this period ends, friction between the teat and open barrel is reduced suddenly because the teat sinus pressure falls. After this stage, the main source of friction appears to be derived from the force between the teat and mouthpiece lip.

SummaryThe teats of quarters which were milked, and those in which milking had ceased, of 16 cows were exposed to bacteria twice daily for 2 weeks by dipping them in a suspension of streptococci and staphylococci.Of 32 quarters in which milking had ceased 22 became infected in this period. Eighteen infections were with Streptococcus dysgalactiae, 2 with Streptococcus uberis, 1 with Staphylococcus aureus and 2 with organisms not used in the culture. Only 3 of 32 milked quarters became infected in the experimental period: 2 infections were with Str. aureus and 1 with an organism not used in the culture. Animals differed in their susceptibility to infection.Quarters which had been unmilked for 2 weeks were as susceptible to new infectionas those in which milking had just ceased.In this experiment, factors such as intramammary pressure, leakage of milk, concentration of bacterial inhibitors, composition of secretion and cell counts of the secretion did not appear to influence the rate of infection. Yield at drying-off, milking rates and teat patency were not related to the differences in susceptibility between animals. It is suggested that the main reason for the lower new infection rate in the milked quarters is that pathogens entering the streak canal or teat sinus are usually flushed out with the secretion during milking and do not cause infection.

SummaryFor radiographic studies of the teat and teatcup liner during milking, quarters were infused with a suspension of propyliodone in milk. Simultaneous recordings of vacuum within the liner, in the mouthpiece chamber and in the pulsation chamber, and recordings of liner-wall movement, were made in conjunction with the radiographs.The studies indicated that the sudden decline in milk flow-rate at the end of the period of peak flow-rate from each quarter, and the concurrent changes in the appearance and position of the teat in the liner, result from a fall in teat sinus pressure. This fall in pressure follows the partial closing of the milk passageway between the teat and udder sinuses. The changes initiating the closing of this connexion seem to occur above the teatcup and are associated with the declining amount of milk in the udder.The teat is elongated by 33–50% as it enters the liner and further stretching of the skin of the teat throughout milking is negligible. Thus, increase in the depth of penetration of the teat into the liner is due to more of the teat entering the top of the liner.The force exerted on the teat by the closed liner, which is greatest near the end of the teat, usually appears to increase near the end of milking. The force acting against the inner surface of the open liner barrel is greatest during the peak flow-rate period and it appears to be fairly uniform over most of the area of contact.

Nine quarters of three cows were used in measuring maximum and residual teat sinus vacua after the end of milk flow at four milking vacuum levels and two pulsator ratios. The increase in maximum and residual teat sinus vacua was nearly linear from 250 to 400mm Hg milking vacuum. Between 400 and 500mm Hg milking vacuum, the increase in maximum teat sinus vacuum was nonlinear and increased rapidly. Congestion of the teat end and signs of discomfort to the cow were observed when the milking vacuum was 500mm Hg. From results of this study, it would appear that a stable milking vacuum above 400mm Hg should be avoided, because of excessive teat sinus vacuum and possible teat injury.

Summary Pressure changes within the intact bovine udder were measured during mechanical milking. Simultaneous pressure recordings were obtained from the teat sinus, gland sinus, pulsator line, and milk line. Indwelling polyvinyl catheters were used to obtain pressure measurements in the teat and gland sinuses. Data from 24 recordings on 12 different quarters of five cows were evaluated. Intramammary pressure increased with milk letdown and was followed by a gradual decline during milk flow. At the end of milk flow a pulsating vacuum developed in the teat sinus, and a residual teat sinus vacuum persisted after inflation collapse. A slight residual gland sinus vacuum also developed after the end of milk flow. After milk removal and teat canal ligation, residual vacuum did not develop in the teat sinus during normal milking machine operation, although a pulsating vacuum was noted. Pressure change in the teat sinus apparently resulted from inflation action upon the teat wall and extension of milk line vacuum through the teat canal.

1. An experiment was carried out with seventy-five dry cows to study the effect of taking samples of udder secretion for bacteriological examination on the incidence of new infection in the early dry period. The incidence of new infection in two quarters of each cow, sampled at weekly intervals after drying off, was compared with that in the remaining two quarters sampled in the fourth and fifth week of the dry period.2. No difference in the new infection rates was found between the quarters that were sampled early in the dry period and those that were not.3. Significantly fewer (P 4. About half of all the new infections persisted until the next lactation.5. It was concluded that if natural sealing of the teat orifice or teat sinus takes place it is of minor importance in preventing infection in the early dry period.

SUMMARY Using a 'within-cow' experimental design the susceptibility of uninfected or Staphylococcus epidermidis infected udder quarters to challenge with Escherichia coli or Streptococcus agalactiae was measured. Twenty-one Staph. epidermidis infected quarters were challenged by infusion of E. coli into the teat sinus and 13 (61·9%) became infected. Fourteen of 15 uninfected quarters challenged similarly with E. coli became infected (93·3%). When another 20 quarters were challenged with Str. agalactiae , one of nine Staph. epidermidis infected quarters (11·1%) and 10 of 11 uninfected quarters became infected. It is suggested that the increased resistance to infection following Staph. epidermidis infection is due to the raised polymorphonuclear leucocyte content of the milk in these quarters rather than any direct inhibition produced by the Staph. epidermidis. The significance of these findings in terms of mastitis control is discussed.

SummaryThe levels of N-acetyl-β-glucosaminidase (NAGase) and acid phosphatase were analysed in tissue from the teat and lactiferous sinus epithelia of dairy cows at different stages of lactation. Enzyme levels were lower in the epithelia of the teat sinus than of the lactiferous sinus. For both enzymes, levels were highest in tissue from post-partum glands, lowest in those from dry and mid-lactation glands. In involuting glands the levels were high, but not as high as the post-partum glands.

The frequency of nuclear bodies was determined in epithelial cells of mammary ductules or alveoli, milk cistern and teat sinus of virgin heifers, non-lactating cows and cows in early lactation. The determined frequency was within the range 12–16% with the single exception of the epithelial cells of secretory alveoli of lactating cows, in which the frequency was 3 %. These data support the concept that nuclear bodies are normal nuclear organelles which can respond to altered physiological conditions.

Teat sinus pressures were studied in cannulated and normal teats of three cows. The presence of a polythene cannula in the teat sinus allowed artificially high residual vacua (50–250 mm mercury) to be recorded during overmilking. In noncannulated teats low levels of residual vacuum (4–12 mm mercury) were found when an alternative method of measurement was used. Immediately the teat cup is removed, residual vacuum in the teat sinus disappears, presumably because milk can move from the gland sinus into the teat once occlusion by the mouth of the liner occurring at the end of milking ceases. When teats were manually occluded before removing the teat cup, even high residual vacuum persisted indefinitely in the teat sinus. This suggests that aspiration of bacteria through the streak canal does not regularly occur.

Public concerns over the widespread prophylactic use of antibiotics have led to a search for alternatives to dry cow therapy for the prevention of intramammary infections. A popular alternative is to infuse a teat seal at drying-off. The teat seal is a viscous non-antibiotic formulation and when it is infused into the teat canal and the teat sinus it forms an internal seal that provides a physical barrier to invasion by mastitis-causing pathogens. Enhancement of teat seal formulations may be achieved using non-antibiotic additives such as bacteriocins, potent proteins produced by some bacteria that have the ability to kill other microorganisms. This paper traces the history of investigations at Moorepark Research Centre into the efficacy of teat seal plus lacticin 3147, a bacteriocin produced by Lactococcus lactis DPC3147, in the prevention of intramammary infections in dry cows. Indications from on-going investigations are that a dry cow formulation combining the two products has considerable potential as a non-antibiotic prophylactic product.