Milk accumulation and distribution in the bovine udder during the interval between milkings

Abstract

SummaryThe proportions of milk stored within the gland cistern (cisternal milk) and within secretory alveolar tissue (alveolar milk) were determined at various intervals after milking in peak lactation cows and late lactation cows. The rate of milk secretion remained constant up to 12 h in both groups. Cisternal milk remained low (600 g or less) until after 4 h in both groups, then increased gradually to values at 12 h of 5·08 (peak lactation) and 2·60 kg (late lactation). Alveolar milk exceeded cisternal milk in both groups and at all time points up to 12 h, and was greatest in the peak lactation cows. A further measurement was made at 20 h in the late lactation group. Milk secretion rate remained constant between 12 and 20 h and most of this additional milk accumulated in the cistern. Alveolar fraction, defined as alveolar milk as a proportion of total milk, ranged from 0·43 to 0·94 at 8 h. There was a highly significant correlation between 8 h and 20 h alveolar milk fraction results, but not between 1 h and 8 h values, nor between alveolar milk at 0 h (effectively residual milk) and alveolar fraction at any time point. The milk volume results were used to construct a mathematical model describing milk flow between cisternal and alveolar compartments, and hence the pattern of milk accumulation. The results are discussed in relation to current hypotheses regarding local autocrine control of milk secretion by a feedback inhibitor in milk.

Robotic milking and milk quality: effects on the cheese-making properties of milk

“…We can suppose that, if cistern volume is not affected, the role of the increased alveoli volume may affect milk fat content and composition. In fact, Friggens and Rasmussen (2001) justified their results in the light of works by Knight et al (1994) and Dewhurst and Knight (1994), who showed that the distribution of milk within the udder was directly related to the time interval since the last milking. The shorter the interval since last milking, the greater the proportion of milk from the alveoli as opposed to the udder cistern.…”

Efeito da massagem do úbere ao final da ordenha no leite residual e na ocorrência de mastite em vacas leiteiras

“…As vacas com produção em torno de 18kg de leite/dia, apresentaram 1,78kg de leite residual, e as de 13kg/dia, 2,42kg. Knight et al (1994) encontraram variação de leite residual de 0,8 a 6,98kg em vacas leiteiras de 27,5kg no pico de lactação (7 semanas pós parto); já para vacas de 13,15kg no final da lactação (28 semanas pós parto) a variação foi de 0,88 a 2,02kg.…”

“…Em contraste, Knight et al (1994) encontraram que as vacas que estão no primeiro terço de lactação têm mais leite residual do que aquelas no último terço de lactação, tanto uma hora após a ordenha quanto após doze horas. Vacas com maior número de parições, e, portanto mais velhas, retêm mais leite após a ordenha (Schmidt et al, 1988) e geralmente são dominantes dentro do grupo.…”

“…Além disso reduz a secreção de leite (Carruthers et al, 1993;Knight et al, 1994;Bruckmaier e Blum, 1998) e conseqüentemente a produção leiteira (Schmidt et al, 1988). A quantidade do leite residual é de aproximadamente 15% do total presente no úbere (Schmidt et al, 1988).…”

“…A quantidade do leite residual é de aproximadamente 15% do total presente no úbere (Schmidt et al, 1988). Vários fatores influenciam a quantidade de leite residual após a ordenha, como a produção leiteira (Gröhn et al, 1995), o estágio de lactação (Knight et al, 1994), a idade (Schmidt et al, 1988), o estresse durante a ordenha (Rushen et al, 2001), a qualidade das relações humano-animais (Rushen et al, 1999), a hierarquia social (Yunes, 2001) e o tipo de ordenha, manual ou mecânica (Schmidt et al, 1988;Gorewit et al, 1992;Bar-Peled et al, 1995).…”