Skip to main content
NCBI home page
The Journal of Physiology logoLink to The Journal of Physiology
. 1980 Jun;303:403–415. doi: 10.1113/jphysiol.1980.sp013295

Milk yield, suckling behaviour and milk ejection in the lactating rat nursing litters of different sizes.

J A Russell
PMCID: PMC1282901  PMID: 7431242

Abstract

1. The quantitative relationship between the suckling stimulus and several suckling-dependent variables was studied in lactating rats. 2. The intensity of the suckling stimulus, measured as the product of duration and number of pups suckling was in proportion to litter size for litters of one, ten or twenty-two pups. 3. Pups in the litters of ten grew fastest. Single-pup litters grew most slowly, some not at all. Litter weight gain, corrected for inevitable losses, was used to estimate milk yield. Total milk yield was greater for litters of twenty-two to twenty-four pups than for litters of ten pups only in the first week. Milk yield for single pups was up to 7% of the yield for ten pups. Milk yield per mammary gland sucked was similar for the larger litters but less for single pups. 4. The number of milk ejections, measured as pup stretch reactions, in observation periods of 225 min, was similar for litters of ten and twenty-two to twenty-four pups, but less for single-pup litters. 5. The suckling stimulus applied by single-pup litters inhibited ovarian growth less effectively than did the stimulus applied by larger litters. 6. There was no change in serum osmolality during lactation. 7. It is concluded that litters of ten or twenty-two to twenty-four pups applied suckling stimuli of different intensities, but these had similar effects on the daily secretion rate of oxytocin, milk production and suppression of ovarian growth. Single-pup litters were less effective.

Full text

PDF
403

Selected References

These references are in PubMed. This may not be the complete list of references from this article.

  1. Baverstock P., Green B. Water recycling in lactation. Science. 1975 Feb 21;187(4177):657–658. doi: 10.1126/science.1167701. [DOI] [PubMed] [Google Scholar]
  2. Beyer C., Mena F. Parturition and Lactogenesis in rabbits with high spinal cord transection. Endocrinology. 1970 Jul;87(1):195–197. doi: 10.1210/endo-87-1-195. [DOI] [PubMed] [Google Scholar]
  3. Brimble M. J., Dyball R. E., Forsling M. L. Oxytocin release following osmotic activation of oxytocin neurones in the paraventricular and supraoptic nuclei. J Physiol. 1978 May;278:69–78. doi: 10.1113/jphysiol.1978.sp012293. [DOI] [PMC free article] [PubMed] [Google Scholar]
  4. Burford G. D., Dyball R. E., Moss R. L., Pickering B. T. Synthesis of both neurohypophysial hormones in both the paraventricular and supraoptic nuclei of the rat. J Anat. 1974 Apr;117(Pt 2):261–269. [PMC free article] [PubMed] [Google Scholar]
  5. Deis R. P. The effect of an exteroceptive stimulus on milk ejection in lactating rats. J Physiol. 1968 Jul;197(1):37–46. doi: 10.1113/jphysiol.1968.sp008543. [DOI] [PMC free article] [PubMed] [Google Scholar]
  6. Drewett R. F., Statham C., Wakerley J. B. A quantitative analysis of the feeding behaviour of suckling rats. Anim Behav. 1974 Nov;22(4):907–913. doi: 10.1016/0003-3472(74)90014-1. [DOI] [PubMed] [Google Scholar]
  7. Dyball R. E. Oxytocin and ADH secretion in relation to electrical activity in antidromically identified supraoptic and paraventricular units. J Physiol. 1971 Apr;214(2):245–256. doi: 10.1113/jphysiol.1971.sp009430. [DOI] [PMC free article] [PubMed] [Google Scholar]
  8. EAYRS J. T., BADDELEY R. M. Neural pathways in lactation. J Anat. 1956 Apr;90(2):161–171. [PMC free article] [PubMed] [Google Scholar]
  9. Edwardson J. A., Eayrs J. T. Neural factors in the maintenance of lactation in the rat. J Endocrinol. 1967 May;38(1):51–59. doi: 10.1677/joe.0.0380051. [DOI] [PubMed] [Google Scholar]
  10. Findlay A. L. The effect of teat anaesthesia on the milk-ejection reflex in the rabbit. J Endocrinol. 1968 Jan;40(1):127–128. doi: 10.1677/joe.0.0400127. [DOI] [PubMed] [Google Scholar]
  11. GROSVENOR C. E. LACTATION IN RAT MAMMARY GLANDS AFTER SPINAL CORD SECTION. Endocrinology. 1964 Apr;74:548–553. doi: 10.1210/endo-74-4-548. [DOI] [PubMed] [Google Scholar]
  12. Hall W. G., Cramer C. P., Blass E. M. Developmental changes in suckling of rat pups. Nature. 1975 Nov 27;258(5533):318–320. doi: 10.1038/258318a0. [DOI] [PubMed] [Google Scholar]
  13. Hofer M. A. Physiological responses of infant rats to separation from their mothers. Science. 1970 May 15;168(3933):871–873. doi: 10.1126/science.168.3933.871. [DOI] [PubMed] [Google Scholar]
  14. Lincoln D. W., Hill A., Wakerley J. B. The milk-ejection reflex of the rat: an intermittent function not abolished by surgical levels of anaesthesia. J Endocrinol. 1973 Jun;57(3):459–476. doi: 10.1677/joe.0.0570459. [DOI] [PubMed] [Google Scholar]
  15. Lincoln D. W., Wakerley J. B. Factors governing the periodic activation of supraoptic and paraventricular neurosecretory cells during suckling in the rat. J Physiol. 1975 Sep;250(2):443–461. doi: 10.1113/jphysiol.1975.sp011064. [DOI] [PMC free article] [PubMed] [Google Scholar]
  16. Mena F., Grosvenor C. E. Effect of suckling and of exteroceptive stimulation upon prolactin release in the rat during late lactation. J Endocrinol. 1972 Jan;52(1):11–22. doi: 10.1677/joe.0.0520011. [DOI] [PubMed] [Google Scholar]
  17. ROTHCHILD I. The corpus luteum-pituitary relationship: the association between the cause of luteotrophin secretion and the cause of follicular quiescence during lactation; the basis for a tentative theory of the corpus luteum-pituitary relationship in the rat. Endocrinology. 1960 Jul;67:9–41. doi: 10.1210/endo-67-1-9. [DOI] [PubMed] [Google Scholar]
  18. Singh P. J., Hofer M. A. Oxytocin reinstates maternal olfactory cues for nipple orientation and attachment in rat pups. Physiol Behav. 1978 Apr;20(4):385–389. doi: 10.1016/0031-9384(78)90317-7. [DOI] [PubMed] [Google Scholar]
  19. Stern J. M., Siegel H. I. Prolactin release in lactating, primiparous and multiparous thelectomized and maternal virgin rats exposed to pup stimuli. Biol Reprod. 1978 Aug;19(1):177–182. doi: 10.1095/biolreprod19.1.177. [DOI] [PubMed] [Google Scholar]
  20. Swaab D. F., Nijveldt F., Pool C. W. Distribution of oxytocin and vasopressin in the rat supraoptic and paraventricular nucleus. J Endocrinol. 1975 Dec;67(3):461–462. doi: 10.1677/joe.0.0670461. [DOI] [PubMed] [Google Scholar]
  21. Teicher M. H., Kenny J. T. Effect of reduced litter size on the suckling behaviour of developing rats. Nature. 1978 Oct 19;275(5681):644–646. doi: 10.1038/275644a0. [DOI] [PubMed] [Google Scholar]
  22. Thatcher W. W., Tucker H. A. Lactational performance of rats injected with oxytocin, cortisol-21-acetate, prolactin and growth hormone during prolonged lactation. Endocrinology. 1970 Feb;86(2):237–240. doi: 10.1210/endo-86-2-237. [DOI] [PubMed] [Google Scholar]
  23. Tribollet E., Clarke G., Dreifuss J. J., Lincoln D. W. The role of central adrenergic receptors in the reflex release of oxytocin. Brain Res. 1978 Feb 17;142(1):69–84. doi: 10.1016/0006-8993(78)90177-4. [DOI] [PubMed] [Google Scholar]
  24. Vorherr H., Kleeman C. R., Lehman E. Oxytocin-induced stretch reaction in suckling mice and rats: a semiquantitative bio-assay for oxytocin. Endocrinology. 1967 Oct;81(4):711–715. doi: 10.1210/endo-81-4-711. [DOI] [PubMed] [Google Scholar]
  25. Wakerley J. B., O'Neill D. S., ter Haar M. B. Relationship between the suckling-induced release of oxytocin and prolactin in the urethane-anaesthetized lactating rat. J Endocrinol. 1978 Mar;76(3):493–500. doi: 10.1677/joe.0.0760493. [DOI] [PubMed] [Google Scholar]
  26. van der Schoot P., Lankhorst R. R., de Roo J. A., de Greef W. J. Suckling stimulus, lactation, and suppression of ovulation in the rat. Endocrinology. 1978 Sep;103(3):949–956. doi: 10.1210/endo-103-3-949. [DOI] [PubMed] [Google Scholar]

Articles from The Journal of Physiology are provided here courtesy of The Physiological Society

RESOURCES