Lactation curves and effect of pup removal on milk fat of C57Bl/6J mice fed different diet fats.
Groups of C57Bl/6J mice, fed either a cis (C-Diet) or trans diet (T-Diet) were milked without preconditioning at 6, 8, 10 and 12 days postpartum. On day 10, groups of mice were also milked 4, 6 and 18 h after separation of the pups. Except for the 18-h separation, all T-Diet fed animals produced milk of lower fat content than did the C-Diet animals (P < 0.001) throughout the lactation period measured. In the C-Diet mice, the 6-h separation period resulted in a decrease (P < or = 0.03) in fat, but the diet-depressed milk fat of T-Diet animals was not decreased further until the 18-h separation period. Milk volume increased as lactation progressed and was greatly increased as a result of preconditioning (P < or = 0.001), even at 4 h of separation when fat was not reduced, and was always greater for T-Diet animals. Within diet groups, fatty acid composition was similar throughout the lactation period studied and was not affected by preconditioning except in the 18-h separation period, when de novo fatty acids were significantly reduced (P < or = 0.05). The data are consistent with the hypothesis that preconditioning results in lowered milk fat values and that preconditioning techniques can explain discrepancies in literature values for murine milk fat.
Teter
B B
BB
Department of Chemistry and Biochemistry, University of Maryland, College Park 20742.
Sampugna
J
J
Keeney
M
M
D000818:Animals; D000833:Animals, Suckling / Q000502:physiology*; D004041:Dietary Fats / Q000008:administration & dosage*; D005227:Fatty Acids / Q000008:administration & dosage* / Q000378:metabolism; D005260:Female; D007774:Lactation / Q000502:physiology*; D050356:Lipid Metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D008892:Milk / Q000378:metabolism*
D004041:Dietary Fats; D005227:Fatty Acids