Fig. 5. A 2 day-old BALB/c pups exposed to a C57Bl/6 female's nipple.Figure optionsDownload full-size imageDownload as PowerPoint slide
3.3. Procedure and behavioral variables
The proportion of pups grasping the nipple and the latency of the first oral grasp response were considered as indices of attraction and appetitive motivation. The number of sucking movements per second was considered to indicate the avidity of oral responses.
After the experiment, the pups were returned into their home cage, whereas the sedated lactating female was placed in a heated individual cage to be watched until full recovery.
3.4. Statistical analyses
3.5. Pup response to the odor of nipples from same-strain females matched/unmatched in lactation age
As shown in Fig. 6, the proportion of C pups that everolimus grasped a nipple was greater when mitosis were exposed to L2-C nipple than when they were exposed to L15-C nipple (p < 0.001). Moreover, C pups grasped more rapidly (U = 73; p < 0.001) and displayed more oral activity on a L2-C nipple than on a L15-C nipple (U = 120; p = 0.019). Similarly, the proportion of B pups that grasped a nipple was higher when they were exposed to L2-B nipple compared with a L15-B nipple (p = 0.016). In addition, B pups grasped with shorter latency (U = 88; p = 0.0003) and higher oral activity (U = 137; p = 0.015) a L2-B nipple than a L15-B nipple. In sum, nipples of same-strain lactating dams elicit significantly more oral grasping on day 2 than on day 15 of lactation in 2 day-old pups.