Pair-Feeding: Definition and Meaning

Pair-feeding is an experimental method in which food intake or energy (calory) intake are limited to become same between animal groups and to exclude effects in the animals by differences of food (energy) intake.

Because foods or nutritions are voluntarily took in animals (rats or mice) but not forced to be given, the intake becomes same when the animals would finish all amounts given. Therefore, amounts of foods are given according to amounts took by animals having lesser intake. The animal group having lesser intake is used as "control" and the animal group given the same amount is called as "pair-fed".

Cases

1. Binge-eating Animals (Obese rats, Obese mice, etc.)
In comparison of binge-eating to normal-eating animals, the same amounts of foods which were consumed by the normal-eating control would be given to the binge-eating animals as a pair-fed group. It makes us study whether the binge-eating contributes their pathological state or not.

• 1) Ishii Y, Ohta T, Sasase T, Morinaga H, Ueda N, Hata T, Kakutani M, Miyajima K, Katsuda Y, Masuyama T, Shinohara M, Matsushita M. Exp Anim. 2010;59(1):73-84. Pathophysiological analysis of female Spontaneously Diabetic Torii fatty rats.
• 2) Elizabeth L. Brandon, Jian-Wei Gu, Lauren Cantwell, Zhi He, Gray Wallace, and John E. Hall. Cancer Biol Ther. 2009 October; 8(19): 1871-1879. Obesity promotes melanoma tumor growth: Role of leptin.
• 3) Ellen E. Ladenheim, Nahketah L. Hamilton, Robert R. Behles, Sheng Bi, Lori L. Hampton, James F. Battey, and Timothy H. Moran. Endocrinology 2008 March; 149(3): 971-978. Factors Contributing to Obesity in Bombesin Receptor Subtype-3-Deficient Mice.

2. Anorectic Animals (Administration of Anorectic Drugs, etc.)
To clarify if pathological and physiological effects in the animals suppressed food intake (control) would be caused from decreases in the food intake or not, normal-eating animals would be given the same amounts of foods consumed by control as a pair-fed group.

• 4) Xavier Prieur, Y. C. Loraine Tung, Julian L Griffin, I Sadaf Farooqi, Stephen O'Rahilly, and Anthony P. Coll1. Endocrinology 2008 November; 149(11): 5432-5439. Leptin regulates peripheral lipid metabolism primarily through central effects on food intake: Effect of leptin on lipid metabolism
• 5) M H Mooney, S Fogarty, C Stevenson, A M Gallagher, P Palit, S A Hawley, D G Hardie, G D Coxon, R D Waigh, R J Tate, A L Harvey, and B L Furman. Br J Pharmacol. 2008 April; 153(8): 1669-1677. Mechanisms underlying the metabolic actions of galegine that contribute to weight loss in mice.
• 6) Stacey L. Conarello, Zhihua Li, John Ronan, Ranabir Sinha Roy, Lan Zhu, Guoqiang Jiang, Franklin Liu, John Woods, Emanuel Zycband, David E. Moller, Nancy A. Thornberry, and Bei B. Zhang. Proc Natl Acad Sci U S A. 2003 May 27; 100(11): 6825-6830. Mice lacking dipeptidyl peptidase IV are protected against obesity and insulin resistance

3. Intake of Palatable Foods
Pair-feeding is used to study whether pathological and physiological effects on intake of highly palatable foods such as high fat diets are caused from overintake of energy or not. To this purpose the same energy of the palatable foods as lesser palatable foods (normal diets) consumed by a control group would be given to a pair-fed group.

• 7) Juliana C. Moraes, Andressa Coope, Joseane Morari, Dennys E. Cintra, Erika A. Roman, Jose R. Pauli, Talita Romanatto, Jose B. Carvalheira, Alexandre L. R. Oliveira, Mario J. Saad, and Licio A. Velloso. PLoS ONE. 2009; 4(4): e5045. High-Fat Diet Induces Apoptosis of Hypothalamic Neurons.
• 8) LeBlanc J, Labrie A. Int J Obes Relat Metab Disord. 1997 Dec;21(12):1100-3. A possible role for palatability of the food in diet-induced thermogenesis.
• 9) Welch CC, Kim EM, Grace MK, Billington CJ, Levine AS. Brain Res. 1996 May 20;721(1-2):126-31. Palatability-induced hyperphagia increases hypothalamic Dynorphin peptide and mRNA levels.

Case 1 might be common.

In other cases, the same number of globular tiny pellets consumed by a control group would be given to a pair-fed group. Becaues a special device always monitors intake of the pellet in the control in this case and promptly gives the pellet to the pair-fed group, a circadian intake pattern of the pellets (foods) might be similar between the both groups although the special pellets are needed.

• 10) Nakagawa T, Tsuchida A, Itakura Y, Nonomura T, Ono M, Hirota F, Inoue T, Nakayama C, Taiji M, Noguchi H. Diabetes. 2000 Mar;49(3):436-44. Brain-derived neurotrophic factor regulates glucose metabolism by modulating energy balance in diabetic mice.

You can conduct a pair-feeding protocol automatically with FDM, Food Intake Monitor and Controller, and software, Feedam-PF, by MELQUEST Ltd. similar as the previous manual protocol. Namely, FDM measures food intake in control for 1 day and limits food intake in pair-fed animals (rats or mice) on the next day to become same as the control intake by closing a electrical shutter. We can also limit food intake in control 10 times a day. For example, it can limit daily food intake seperately in light and dark periods or every 3 hours. This protocol is different from that in literature 10) and an augmented technique from the previous manual pair-feeding in which it limits food intake in pair-fed animals besed on the intake in control animals yesterday.
We can set available feeding periods and weights. If we set the least intake in all animals as the available weights, the food intake in all animals might be same.

FDM is a newly developed device and there is no report published of pair-feeding by FDM and Feedam-PF (MELQUEST Ltd.).