Living together, feeding apart: How to measure individual food consumption in social house mice

Abstract

In many studies with animals kept in groups, scientists need information about each individual's food access without disturbance or separation of the animals. We developed an automatic feeding device that allows measurement of individual food consumption and experimental manipulation of individual food availability in small social mammals, such as house mice. The feeding device is based on radio frequency identification that triggers access to a motor-driven metal arm filled with food pellets and is mediated with the help of subcutaneously implanted transponders.The ability to measure and manipulate individual food consumption is ofparamount importance for many topics involving animal research in ethology, psychology, and physiology. Although this is a rather easy task when animals are kept solitarily, it often raises problems with social species kept in groups. Here, individual food consumption typically can only be measured with some interference by the experimenter and, thus, disturbance ofthe animals.To avoid such problems, we developed an automatic feeding device that allows unobtrusive, separate, and exclusive food access for several individuals living in a social group.We have used this device to study the maternal investment of female house mice that cooperatively rear their young in a communal nest and indiscriminately nurse their own and alien young (see, e.g., Konig, 1989aKonig, , 1989b, I 994b). Maternal Investment in Communally Nursing House MiceAs in most mammals, milk production is a large investment for a mouse mother (Bronson, 1989; CluttonBrock, 1991). Milk production is costly not only in terms of energy, but also in terms of decreased future reproduction (Konig, Riester, & Markl, 1988). With increased litter size and correspondingly increased milk production, the birth of the female's next litter is delayed. Because of such costs, we expect females that share a communal nest to mutualistically nurse nonoffspring. As a

Challenges in quantifying food intake in rodents

“…Experimental approaches for quantifying food intake in group-housed rodents have made progress with RFID technology. In 2000, a research group first demonstrated the potential for using implantable RFID chips to identify rodents for the purpose of scoring feeding behaviors (Neuhausser-Wespy and Konig, 2000). Another group followed up on their approach, demonstrating a highly accurate system using RFID identification for monitoring feeding of rats from a pellet dispenser (Holley et al, 2003).…”

Non-offspring nursing in mammals: general implications from a case study on house mice

“…Daily food consumption of females was measured from day 2 until day 13 of lactation with the help of an automatic feeding device (Neuhäusser-Wespy & König 2000). This device allows measuring individual food consumption of group-living animals without any disturbance.…”