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. Author manuscript; available in PMC: 2015 Mar 10.
Published in final edited form as: J Anim Sci. 2011 Dec 28;90(5):1695–1707. doi: 10.2527/jas.2011-4790

Figure 1.

Figure 1

Litter size is positively correlated with mammary cell number (A), activity (B), and milk yield (C) in lactating rats (redrawn from Tucker, 1966). On d 3 of lactation, litters were adjusted to two, four, or six pups per six glands (thoracic teats were ligated). Throughout lactation, mammary glands were collected and nucleic acid content measured on the days indicated. The amount of DNA was used as an indicator of mammary cell number, whereas the ratio of RNA to DNA was used as an indicator of mammary cell activity. Milk yield was estimated by litter weight gain, which was measured on d 16 of lactation.