| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
|
|
|
|||||||
|
|||||||||
Unité Mixte de Recherches INRA/Agrocampus Rennes Production du Lait, 33590 Saint-Gilles, France
1 Corresponding author: Jocelyne.Flament{at}agrocampus-rennes.fr
Increasing the milking interval decreases milk yield and modifies milk composition. To gain a clearer understanding of the regulation of milk yield and composition, a study was conducted to establish the response curves of nutrient extraction by the mammary gland and mammary epithelial permeability in response to increasing milking intervals. Four multiparous lactating dairy cows were milked at 8-, 12-, 16-, or 24-h intervals over a period of 7 d using a Latin square design. Between the 8- and 24-h milking intervals, milk yield and milk protein levels fell curvilinearly from 38.2 to 29.2 kg/d and from 1,086 to 827 g/d, respectively. Milk fat yield decreased linearly from 1,475 to 1,235 g/d. Indicators of the opening of tight junctions increased linearly with increasing milking intervals: milk BSA increased from 148 to 207 mg/L and plasma lactose increased from 22.9 to 32.0 mg/L. The mammary gland’s ability to extract nutrients decreased with increasing milking intervals. Extraction rates of glucose, ß-hydroxybutyrate, and total glycerol decreased significantly (from 27.2 to 23.3%, from 42.3 to 34.4%, from 36.6 to 30.8% between 8- and 24-h milking intervals, respectively), and not significantly for 
-amino nitrogen (from 23.2 to 20.0%). The extraction rate of acetate remained constant. Moreover, the extraction of milk fat precursors appeared to be less regulated than those of the precursors of milk protein and lactose, which could partly explain why milk yield and milk protein yield decreased more than milk fat yield. The arteriovenous differences of ß-hydroxybutyrate and total glycerol remained constant, whereas those of glucose decreased significantly from 0.98 to 0.87 ± 0.05 mmol/L and not significantly from 0.74 to 0.64 ± 0.12 mmol/L for -amino nitrogen. As a result, the mammary gland’s ability to extract nutrients appears to be downregulated explaining partly the decrease in daily milk yield observed in response to increased milking intervals.
Key Words: dairy cow • milking frequency • mammary nutrient extraction • mammary epithelium permeability
This article has been cited by other articles:
|
|
 |
|
  E. H. Wall and T. B. McFadden Use it or lose it: Enhancing milk production efficiency by frequent milking of dairy cows J Anim Sci, March 1, 2008; 86(13_suppl): 27 - 36. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
K. M. Svennersten-Sjaunja and G. Pettersson Pros and cons of automatic milking in Europe J Anim Sci, March 1, 2008; 86(13_suppl): 37 - 46. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 F. Calderon, B. Chauveau-Duriot, P. Pradel, B. Martin, B. Graulet, M. Doreau, and P. Noziere Variations in Carotenoids, Vitamins A and E, and Color in Cow's Plasma and Milk Following a Shift from Hay Diet to Diets Containing Increasing Levels of Carotenoids and Vitamin E J Dairy Sci, December 1, 2007; 90(12): 5651 - 5664. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
J. Guinard-Flament, E. Delamaire, P. Lamberton, and J. L. Peyraud Adaptations of Mammary Uptake and Nutrient Use to Once-Daily Milking and Feed Restriction in Dairy Cows J Dairy Sci, November 1, 2007; 90(11): 5062 - 5072. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
F. Calderon, B. Chauveau-Duriot, B. Martin, B. Graulet, M. Doreau, and P. Noziere Variations in Carotenoids, Vitamins A and E, and Color in Cow's Plasma and Milk During Late Pregnancy and the First Three Months of Lactation J Dairy Sci, May 1, 2007; 90(5): 2335 - 2346. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
E. Delamaire and J. Guinard-Flament Increasing milking intervals decreases the mammary blood flow and mammary uptake of nutrients in dairy cows. J Dairy Sci, September 1, 2006; 89(9): 3439 - 3446. [Abstract] [Full Text] [PDF]
|
|
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
