When unexpectedly switched from a preferred to a less-preferred food reward, non-human animals may decrease consumption below that when only receiving the less-preferred reward - a successive negative contrast (SNC) effect. SNC has been proposed as an animal welfare indicator, however, to be effective it should show external validity; being demonstrable outside of highly standardized laboratory settings. We therefore investigated whether the SNC effect typically shown in laboratory rats was observed in owned (pet) rats from heterogeneous non-laboratory environments. Subjects (N = 14) were tested in a consummatory SNC paradigm with solid food rewards. "Shifted" rats received a high-value reward for 10 days (pre-shift), a low-value reward for six days (post-shift), then one additional day of high-value reward (re-shift). "Unshifted" rats always received the same low-value reward. "Shifted" rats consumed more food during pre-shift and re-shift trials, but ate less of the low-value food than "unshifted" animals in the post-shift trials - a SNC effect. This confirms the external validity of the SNC paradigm, extending reproducibility to outside the laboratory, indicating translatability across contexts, thus enhancing its potential use as a welfare indicator.

中文翻译：

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评估连续负对比度的外部有效性-对动物福利的影响。

当非预期的食物奖励从偏爱的奖励转换为偏爱的食物时，非人类动物可能会减少消费，低于仅获得偏爱的奖励时的消费-连续的负面对比（SNC）效果。已经提议将SNC作为动物福利指标，但要使其有效，它应该表现出外部有效性。在高度标准化的实验室环境之外可以证明。因此，我们调查了是否在异类非实验室环境的自有（宠物）大鼠中观察到通常在实验室大鼠中表现出的SNC效应。受试者（N = 14）在具有固态食品奖励的完善SNC范式中接受测试。“转移的”大鼠在10天（换班前）获得高价值奖励，在六天的时间（换班后）获得低价值的奖励，然后再获得一天的高价值奖励（换班）。”