Studies on Lactation

Daggs, R. G.

doi:10.1093/jn/9.5.575

Cited by 8 publications

(2 citation statements)

References 3 publications

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“…It is evident that the logistic gives a better fit over the whole range than either of the logarithmic equations over its restricted range. The point of inflexion of the logistic comes at t = 9-6 days, which is close to the values given by Brody [1927] and Daggs [1935] as the point of intersection of the logarithmic curves fitting their data, but it is clear from what has been said that our litters experienced no such sharp discontinuity in growth at this time as postulated by these authors.…”

Section: The Equation Of the Litter-growth Curvesupporting

confidence: 90%

The Measurement of Lactational Performance in the Rat in Studies of the Endocrine Control of Lactation

Cowie¹,

Folley²

1946

Journal of Endocrinology

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A serious difficulty in lactational studies on small laboratory animals is the lack of a satisfactory means of milking them and thus directly measuring their milk yields. At present, lactational performance in rats can only be inferred from litter growth and survival data determined under carefully standardized conditions. Comparison of litter-growth curves (and survival data) for different groups of rats gives some idea of their relative lactational performances but it is not possible to calculate daily milk yields from such curves since the weight losses due to the excreta and insensible perspiration are unknown.Attempts to determine true milk yields by the complicated and not entirely unobjectionable (see discussion by Enzmann) procedures used by Enzmann [1933] for mice and by Brody & Nisbet [1938] for rats, which involve determination not only of the daily litter weight gains but also of the daily losses due to the excreta and perspiration, are clearly impracticable in experiments carried out on any considerable scale. Thus when, in the course of studies of the relation between the adrenal cortex and lactation [Cowie & Folley, 1946a, b], we wished to determine quantitatively the lactational responses of adrenalectomized rats to treatment with adrenal cortex hormones, we had to devise a quantitative criterion of lactation which was derived solely from the ordinary litter-growth curve. THE EQUATION OF THE LITTER-GROWTH CURVEDaggs [1935] proposed a 'lactation index' for rats based on the claim (in which respect he followed Brody [1927]) that the points obtained by plotting the logarithm of the mean weight of the young against time fall along two straight lines which intersect at approximately í = 10 days. The numerical index used by Daggs has, however, little theoretical significance and cannot be used for quantitative comparisons even if the premises on which it is based are true.We have constructed a mean growth curve (Fig.

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Section: The Equation Of the Litter-growth Curvesupporting

confidence: 90%

The Measurement of Lactational Performance in the Rat in Studies of the Endocrine Control of Lactation

Cowie¹,

Folley²

1946

Journal of Endocrinology

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“…Enzmann (1933) and Brody & Nisbet (1938) carried out intricate measurements of perspiration and excreta to correct the live-weight increases of the pups. Daggs (1935) and Cowie & Folley (1947) used the live-weight increases of the pups to calculate 'lactation' and 'litter growth' indices respectively. These indices served as the criterion for comparing the milk yield of different rats.…”

Section: Moragmentioning

confidence: 99%

Estimation of milk yield in the rat

Morag¹

1970

Lab Anim

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The biases inherent in the use of the growth curves of the litter and of milking devices to estimate milk yield in the rat are discussed. A method is described in which the pups are separated from their dams for a period of hours and are then allowed to suck for about 60 minutes. The increase in litter weight during suckling is used as an estimate of milk secretion during the period of separation. Various components of this method were examined and it was shown that (i) the rate of milk secretion in the rat is constant for at least 16 h; (ii) the administration of oxytocin at suckling does not influence the yield at that suckling, but does increase the rate of milk removal; (iii) gland evacuation is completed within 50 to 60 minutes of suckling; (iv) the emptying of the mammary gland prior to the secretion interval increases the sensitivity of the estimate of milk yield; (v) the yield after a standard period of separation is a function of the level of hunger of the litter prior to suckling; (vi) cross-fostering and frequent randomized reallocation of pups between treatment groups eliminate biases inherent in earlier methods. The problems associated with the technique are discussed and a laboratory routine is outlined. The use of the technique in cross-over designs is advocated.

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A Note on the Effects of Feeding Saw Palmetto Berries, Serenoa Repens (Bartram) Small, to Rats

Feurt

Fox²

1954

Journal of the American Pharmaceutical Association (Scientific

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Studies on Lactation

Cited by 8 publications

References 3 publications

The Measurement of Lactational Performance in the Rat in Studies of the Endocrine Control of Lactation

The Measurement of Lactational Performance in the Rat in Studies of the Endocrine Control of Lactation

Estimation of milk yield in the rat

A Note on the Effects of Feeding Saw Palmetto Berries, Serenoa Repens (Bartram) Small, to Rats

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