Abstract
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.(ABSTRACT TRUNCATED AT 250 WORDS)
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Selected References
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- Blatchford D. R., Peaker M. Effects of frequent milking on milk secretion during lactation in the goat: relation to factors which limit the rate of secretion. Q J Exp Physiol. 1982 Apr;67(2):303–310. doi: 10.1113/expphysiol.1982.sp002638. [DOI] [PubMed] [Google Scholar]
- Fleet I. R., Peaker M. Mammary function and its control at the cessation of lactation in the goat. J Physiol. 1978 Jun;279:491–507. doi: 10.1113/jphysiol.1978.sp012358. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Henderson A. J., Blatchford D. R., Peaker M. The effects of milking thrice instead of twice daily on milk secretion in the goat. Q J Exp Physiol. 1983 Oct;68(4):645–652. doi: 10.1113/expphysiol.1983.sp002754. [DOI] [PubMed] [Google Scholar]
- Linzell J. L., Mepham T. B., Peaker M. The secretion of citrate into milk. J Physiol. 1976 Sep;260(3):739–750. doi: 10.1113/jphysiol.1976.sp011541. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Linzell J. L., Peaker M. Intracellular concentrations of sodium, potassium and chloride in the lactating mammary gland and their relation to the secretory mechanism. J Physiol. 1971 Aug;216(3):683–700. doi: 10.1113/jphysiol.1971.sp009547. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Linzell J. L., Peaker M. Mechanism of milk secretion. Physiol Rev. 1971 Jul;51(3):564–597. doi: 10.1152/physrev.1971.51.3.564. [DOI] [PubMed] [Google Scholar]
- Linzell J. L., Peaker M. The effects of oxytocin and milk removal on milk secretion in the goat. J Physiol. 1971 Aug;216(3):717–734. doi: 10.1113/jphysiol.1971.sp009549. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Maule Walker F. M., Peaker M. Local production of prostaglandins in relation to mammary function at the onset of lactation in the goat. J Physiol. 1980 Dec;309:65–79. doi: 10.1113/jphysiol.1980.sp013494. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Neville M. C., Peaker M. Ionized calcium in milk and the integrity of the mammary epithelium in the goat. J Physiol. 1981;313:561–570. doi: 10.1113/jphysiol.1981.sp013682. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Peaker M. Mechanism of milk secretion: milk composition in relation to potential difference across the mammary epithelium. J Physiol. 1977 Sep;270(2):489–505. doi: 10.1113/jphysiol.1977.sp011964. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Peaker M. The effect of raised intramammary pressure on mammary function in the goat in relation to the cessation of lactation. J Physiol. 1980 Apr;301:415–428. doi: 10.1113/jphysiol.1980.sp013214. [DOI] [PMC free article] [PubMed] [Google Scholar]