Feed-back control of milk secretion in the goat by a chemical in milk

In order to investigate the nature of the inhibition of milk secretion during a long milking interval, goats were treated in three possible ways: (i) milked twice daily at 08.00 h and 16.00 h or (ii) milked thrice daily at 00.00 h, 08.00 h and 16.00 h, or (iii) milked thrice daily at 00.00 h, 08.00...

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Bibliographic Details
Published in:The Journal of physiology 1984-06, Vol.351 (1), p.39-45
Main Authors: Henderson, A J, Peaker, M
Format: Article
Language:English
Subjects:
Animals
Biological and medical sciences
Calcium - metabolism
Citrates - metabolism
Feedback
Female
Fundamental and applied biological sciences. Psychology
Goats - physiology
Hormone metabolism and regulation
Lactation
Lactose - metabolism
Milk - metabolism
Milk Proteins - metabolism
Pregnancy
Pregnancy. Parturition. Lactation
Secretory Rate
Sodium - metabolism
Sucrose - pharmacology
Vertebrates: reproduction
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Summary:In order to investigate the nature of the inhibition of milk secretion during a long milking interval, goats were treated in three possible ways: (i) milked twice daily at 08.00 h and 16.00 h or (ii) milked thrice daily at 00.00 h, 08.00 h and 16.00 h, or (iii) milked thrice daily at 00.00 h, 08.00 h and 16.00 h, but at 00.00 h the milk removed was replaced with an equal volume of isosmotic sucrose solution. The latter treatment was carried out in order to subject the gland to a degree of physical distension equivalent to that on treatment (i). On either thrice-daily milking or thrice-daily milking with sucrose replacement, milk secretion rate over the 16.00-08.00 h period was significantly higher (by about 10% in both cases) than on twice-daily milking. Secretion rates of lactose, milk protein, citrate and calcium during the 00.00-08.00 h period were similar on either thrice-daily milking or thrice-daily milking with sucrose replacement; the secretion rate of fat was significantly higher on thrice-daily milking with sucrose replacement. Secretion rates of Na+, K+ and Cl- were significantly higher on thrice-daily milking with sucrose replacement. In the case of Na+, the increased Na+ secretion rate was sufficient to create a normal Na+ concentration in the milk/sucrose mixture removed at the next milking. In the cases of K+ and Cl-, their secretion rates were not sufficient to restore their concentrations to normal by the next milking.
ISSN:0022-3751
1469-7793
DOI:10.1113/jphysiol.1984.sp015230