Variation with season and lactation of plasmin and plasminogen concentrations in Montbeliard cows' milk

Abstract

Plasmin and plasminogen were determined monthly over a one year period in samples of bulk and herd milks from Montbeliard cows. Montbeliard milk showed a high content of plasmin and plasminogen in comparison with milk from other breeds. In bulk milk, the plasmin activity reached a minimum in September (015/tg/ml milk) and a maximum in June (032/ig/ml milk). The annual mean concentration was 0-23 /ig/ml milk. The plasminogen content varied around a value of 1-28 /tg/ml milk, with a marked decrease in September (0-83 /ig/ml milk) and a maximum in October (l -59 /tg/ml milk). In herd milk, the minimum plasmin activity occurred in October (0-17 /ig/ml milk) and the maximum in spring (0-42 fig/'ml milk in May) with an annual mean of 0-30 /tg/ml milk. The plasminogen content varied in a similar way, from 0-87 fig/ml milk to 1'82 /tg/ml milk, with an annual mean of 1-46/tg/ml. The ratio plasminogen: plasmin ranged from 1-4 to 9-2 with an average of 4-9. From early to late lactation, plasmin and plasminogen concentrations increased from 0-25 to 0-38 /tg/ml milk and from 1-07 to 2-01 fig/m\ milk respectively and the plasminogen: plasmin ratio increased from 4-5 to 5-3. Studies of milk from cows at similar stage of lactation within a single herd have shown the necessity for distinguishing between two phases in the early stage of lactation. The first, a very early period, is usually present up to one month and the second occurs in the second and third months. Milk samples with the highest proportion of -y-caseins were not those with the greatest plasmin content but were those with high plasminogen contents, which had increased suddenly from the levels of the preceding month. This suggests a role for the plasminogen activator and inhibitor system.

The suitability of milk from a spring-calved dairy herd during the transition from normal to very late lactation for the manufacture of low-moisture Mozzarella cheese

“…Similar changes in milk composition have been reported in other countries, e.g., Australia (Auldist et al, 1996;Walker, Dunschea, & Doyle, 2004), Canada (Kroeker, Ng-Kwai-Hang, Hayes, & Moxley, 1985), France (Martin & Coulon, 1995), New Zealand (Auldist, Walsh, & Thomson, 1998;Nicholas, Auldist, Molan, Stelwagen, & Prosser, 2002) and the UK (Banks & Tamime, 1987). Factors contributing to these changes include the combined effects of differences in stage of lactation (which alters the udder physiology and metabolism), plane of nutrition (especially for cows fed on pasture grass), somatic cell count and season (Benslimane, Dognin-Bergeret, Berdague, & Gaudemer, 1990;Givens, Moss, & Adamson, 1993;Hurley & Ford, 2003;Nicholas et al, 2002).…”

Microparticle‐enhanced nephelometric immunoassay of plasminogen in bovine milk

“…The concentrations assayed in herd milks with this microparticle-enhanced nephelometric immunoassay ranged from 1.1 to 4.9 mg I" 1 . They were close to those previously reported using another immunological method (2.6-4.8 mg I" 1 by Collin et al, 1988) but were often slightly higher than the levels obtained by the spectrophotometric methods based on the measurement of bPl activity (0.2-2.8 mg I" 1 ; Richardson & Pearce, 1981;Korycka-Dahl et al, 1983;Rollema et al, 1983;Benslimane et al, 1990). Month-bymonth comparison of the results of this study indicated a possible seasonal variation of the bPIg concentration in milk.…”

“…Month-bymonth comparison of the results of this study indicated a possible seasonal variation of the bPIg concentration in milk. Such a variation has been already observed, with an increase of bPl activity in the summer (Benslimane et al, 1990). However, this seasonal variation could also be the consequence of the stage of lactation, milk bPIg levels reaching 12 mg 1~ ' and even 30 mg I" 1 (Kaartinen & Pyörälä, 1989;Dupont et al, 1995) during early lactation.…”

Relationships between ruminant management and sensory characteristics of cheeses: a review

“…This proteolysis is due to plasmin, whose activity increases in late lactation [11], especially when SCC are high [5]. Plasmin is certainly also involved in the texture differences noted between valley and mountain cheeses in Bugaud et al's trial [17] or between the north and south sides of the same pasture [16], as its activity was highly variable from one situation to another.…”