Behavioral variation among cloned pigs

The variability of behavior among cloned animals has yet to be studied. Through a series of behavior tests, we quantified the variation in food preference, temperament, and time budgets of two genetically identical Duroc litters (n = 5, 4) and their naturally bred controls (n = 4, 4). All litters of pigs were tested for their food preference using apples, bananas, crackers, and carrots. Variation in temperament was determined by timing latency to remove a towel (Towel Test) and by counting vocalizations and escape attempts during Back and Pick-up Tests. Seventy-two hours of time lapse video were used to determine time budgets of the pigs consisting of the following behaviors: lying in bedding, lying on concrete, standing, feeding, and play/fighting. An F-test was used to determine differences in variation between litter variations. The clones were similarly or more variable (P < 0.05) than the naturally bred controls: in their preference for the foods in 13 of the 160 comparisons; in 5 of the 8 comparisons during the Towel Test; in all four comparisons in the Back and Pick-up Tests; and in 9 of the 10 comparisons in the time budget analysis. These results reinforce the importance of environmental effects on animal behavior and question the use of cloning by nuclear transfer to replicate animals with specific behavioral characteristics. (C) 2003 Elsevier Science B.V. All rights reserved.