Changes in Alveolar and Cisternal Compartments Induced by Milking Interval in the Udder of Dairy Ewes

Abstract

The aim of this work was to evaluate the effects of milking interval (4, 8, 12, 16, 20, and 24 h) on cisternal size and milk partitioning (cisternal and alveolar) in the udders of dairy ewes. Twenty-four dairy ewes (Manchega, n = 12; Lacaune, n = 12) were used in a 2-wk experiment during mid-lactation. Cisternal and alveolar milk yields were measured and milk samples from each udder fraction were collected for analysis. Cisternal milk was obtained after i.v. injection of an oxytocin receptor antagonist, and alveolar milk was obtained after i.v. injection of oxytocin. Enlargement of the cisternal compartment due to milking intervals was measured by ultrasonography for each half udder. Volumes of cisternal and alveolar milk differed according to breed, being greater in Lacaune (888 +/- 43 and 338 +/- 25 mL, respectively) than in Manchega ewes (316 +/- 43 and 218 +/- 25 mL, respectively). Alveolar milk increased linearly to 16 h in Manchega and 20 h in Lacaune and remained constant thereafter. Cisternal milk accumulated linearly to 24-h milking intervals in both breeds. Cisternal area (values per udder half) increased as milking interval increased, reaching a plateau at 20 h in Manchega (21 +/- 1 cm(2)) and 16 h in Lacaune (37 +/- 1 cm(2)). Correlation between cisternal area and cisternal milk was the greatest at 8 h (Manchega: r = 0.70 and Lacaune: r = 0.56). Cisternal area correlated with total milk (r = 0.80). Milk fat content varied markedly with milking intervals, increasing in alveolar milk (until 12 h in Manchega, 8.90 +/- 0.18%; and 20 h in Lacaune, 8.67 +/- 0.19%) and decreasing until 24 h in cisternal milk (5.74 +/- 0.29% and 4.85 +/- 0.29%, respectively). Milk protein content increased in alveolar milk until 24 h (Manchega, 6.46 +/- 0.11%; Lacaune, 5.95 +/- 0.11%), but did not vary in cisternal milk. Milk lactose content only decreased at the 24-h milking interval in the cisternal milk of Manchega ewes (4.60 +/- 0.04%). In conclusion, our results suggest that cisterns play an important role in accommodating secreted milk during extended milking intervals. Thus, long milking intervals could be a recommended strategy for large-cisterned dairy sheep. Evidence indicates that ultrasonography provides accurate estimations of udder cistern size and could be used as an indicator for selecting large-cisterned dairy ewes.

Effects of breed and milking frequency on udder histological structures in dairy goats

“…CMY and AMY are positively correlated with the milk-yielding parameters (TM, r 00.99 and r00.86; HP, r00.53 and r00.50, for cisternal and alveolar milk quantity, respectively). These results are in concordance with Castillo et al (2008), who found these correlations in dairy ewes (TM at 16 h, r 00.89 and r00.70; TM at 24 h, r00.93 and r00.68, for cisternal and alveolar milk, respectively). The percentages of the milk partitioning (CMP and AMP) have no correlation with the milk-yielding parameters.…”

“…The percentages of the milk partitioning (CMP and AMP) have no correlation with the milk-yielding parameters. The percentage of fat contained in the milk is positively correlated with AMP due to the alveolar milk being richer in fat Ayadi et al 2004;Castillo et al 2008). These percentages present correlations with the main tissue components (secretory tissue, r00.48, connective tissue, r0 (0.54, for alveolar milk percentage).…”

“…During the 6 weeks of experimentation, once a week, to evaluate milk partitioning in the udder, according to Castillo et al (2008), the goats were injected (i.v.) with 0.8 mg of OT receptor blocking agent (Atosiban, Ferring Lab., Mallmo¨, Sweden).…”

The level of udder emptying and milk flow stability in Tsigai, Improved Valachian, and Lacaune ewes during machine milking

“…In our conditions, breed Lacaune had almost double cisternal volume than Tsigai and Improved Valachian (Milerski et al, 2006). High-yielding Lacaune ewes presented greater cisternal milk percentages and more cisternal milk than mediumyielding ewes (Castillo et al, 2008).…”

Estimation of udder cistern size in dairy ewes by ultrasonography

“…Cistern size is an important factor in determining the milkability (L abussière, 1988; Marnet and McKusick, 2001) and the adequate interval between milkings (Knight and Dewhurst, 1994;Salama et al, 2003). Animals that store a large proportion of milk in the gland cistern produce more milk, and are more able to tolerate extended milking intervals (Salama et al, 2004;Castillo et al, 2008b;Castillo et al, 2009). Moreover, cistern size plays an important role in controlling milk secretion because when the cistern reaches its full capacity, physical pressure and FIL concentration within alveoli are increased (Wilde et al, 1996).…”