Protein Hydrolysates Are Avoided by Herbivores but Not by Omnivores in Two-Choice Preference Tests

Background: The negative sensory properties of casein hydrolysates (HC) often limit their usage in products intended for human consumption, despite HC being nutritious and having many functional benefits. Recent, but taxonomically limited, evidence suggests that other animals also avoid consuming HC when alternatives exist. Methodology/Principal Findings: We evaluated ingestive responses of five herbivorous species (guinea pig, mountain beaver, gopher, vole, and rabbit) and five omnivorous species (rat, coyote, house mouse, white-footed mouse, and deer mouse; N = 16–18/species) using solid foods containing 20% HC in a series of two-choice preference tests that used a nonprotein, cellulose-based alternative. Individuals were also tested with collagen hydrolysate (gelatin; GE) to determine whether it would induce similar ingestive responses to those induced by HC. Despite HC and GE having very different nutritional and sensory qualities, both hydrolysates produced similar preference score patterns. We found that the herbivores generally avoided the hydrolysates while the omnivores consumed them at similar levels to the cellulose diet or, more rarely, preferred them (HC by the white-footed mouse; GE by the rat). Follow-up preference tests pairing HC and the nutritionally equivalent intact casein (C) were performed on the three mouse species and the guinea pigs. For the mice, mean HC preference scores were lower in the HC v C compared to the HC v Cel tests, indicating that HC’s sensory qualities negatively affected its consumption. However, responses were species-specific. For the guinea pigs, repeated exposure to HC or C (4.7-h sessions; N = 10) were found to increase subsequent HC preference scores in an HC v C preference test, which was interpreted in the light of conservative foraging strategies thought to typify herbivores. Conclusions/Significance: This is the first empirical study of dietary niche-related taxonomic differences in ingestive responses to protein hydrolysates using multiple species under comparable conditions. Our results provide a basis for future work in sensory, physiological, and behavioral mechanisms of hydrolysate avoidance and on the potential use of hydrolysates for pest management.

IMMIGRATION, THE AMERICAN WEST, AND THE TWENTIETH CENTURY: GERMAN FROM RUSSIA, OMAHA INDIAN, AND VIETNAMESE-URBAN VILLAGERS IN LINCOLN, NEBRASKA

The North American West is a culturally and geographically diverse region that has long been a beacon for successive waves of human immigration and migration. A case in point, the population of Lincoln, Nebraska -- a capital city on the eastern cusp of the Great Plains -- was augmented during the twentieth century by significant influxes of Germans from Russia, Omaha Indians, and Vietnamese. Arriving in clusters beginning in 1876, 1941, and 1975 respectively, these newcomers were generally set in motion by dismal economic, social, or political situations in their sending nations. Seeking better lives, they entered a mainstream milieu dominated by native-born Americans -- most part of a lateral migration from Iowa, Illinois, and Pennsylvania -- who only established their local community in 1867. While this mainstream welcomed their labor, it often eschewed the behaviors and cultural practices ethnic peoples brought with them. Aware but not overly concerned about these prejudices, all three groups constructed or organized distinct urban villages. The physical forms of these enclaves ranged from homogeneous neighborhoods to tight assemblies of relatives, but each suited a shared preference for living among kinspeople. These urban villages also served as stable anchors for unique peoples who were intent on maintaining aspects of their imported cultural identities. Never willing to assimilate to mainstream norms, urban villagers began adapting to their new milieus. While ethnic identity constructions in Lincoln proved remarkably enduring, they were also amazingly flexible. In fact, each subject group constantly negotiated their identities in response to interactions among particular, cosmopolitan, and transnational forces. Particularism refers largely to the beliefs, behaviors, and organizational patterns urban villagers imported from their old milieus. Cosmopolitan influences emanated from outside the ethnic groups and were dictated largely but not exclusively by the mainstream. Transnationalism is best defined as persistent, intense contact across international boundaries. These influences were important as the particularism of dispersed peoples was often reinforced by contact with sending cultures. Adviser: John. R. Wunder