Public Feeding Interactions as Enrichment for Three Zoo-Housed Elephants

The past two decades have seen increased interest in studies examining the welfare of elephants and animal–visitor interactions. One understudied area for both pursuits is the impact of public feeding interactions. Our study examined the effects of public feedings on the general activity of three zoo-housed elephants. Prior to public feedings, we developed and assessed a 21-behavior ethogram split into six classes of behavior. Comparisons between the elephants demonstrated that only one of the elephants engaged in stereotypies with regularity (>30%), and that the stereotypies occurred in place of most foraging. During public feedings, we compared the general activity of each elephant independently and across both public feeding and nonpublic feeding days, as well as the general activity before, during, and after a public feeding. Public feedings increased social activity and decreased stereotypies when compared with nonpublic feeding days for two of the elephants. In addition, all three elephants showed increased foraging and decreased inactivity in the period after a public feeding session. These results demonstrate that public feedings can be a useful tool for enriching the welfare of zoo-housed elephants and are among the first sets of data to demonstrate positive welfare outcomes associated with public feedings.

Characterizing Caregiver Verbalizations to Infants During the Introduction of a Novel Food

Objectives To characterize parental verbal prompts to infants during feeding and the relation of parent verbalizations to infant acceptance of a novel food. Methods Feeding interactions of parent-child dyads (n = 106; 54% boys; mean age 13.3 ± 4.9 mo) were video-recorded and all parental verbal communications to infants and infant acceptance/rejection of the bites were coded. Verbal prompts, defined a priori, were categorized as positive (8 codes, e.g., verbal encouragement), neutral (4 codes, e.g., comments about color of food) and negative (6 codes, e.g., pressure) prompts. Trained coders classified each utterance and recorded the number and rate of bites accepted (mean K = .81 for all codes). Frequency of verbal prompts were examined by infant sex (M/F), age (6–11.9, 12–17.9, & 18–24 mo), and over the course of the feeding using Wilcoxon rank sums & Kruskal Wallis tests (p < .05). Spearman's rho tested associations between verbalization frequency and both the number of accepted and rejected bites and the rate of bite acceptance. Results Total parent verbalizations increased with infant age (p = .002). No differences were noted by infant sex. Positive verbalizations declined over the course of the feed (p = .02), whereas neutral (p = .20) and negative (p = .09) verbalizations exhibited no significant change. Total verbalizations were positively correlated with the number of rejected bites (p = .0009). In contrast, fewer negative verbalizations were correlated with more accepted bites (p = .02) and a lower rate of acceptance (p = .002). The absence of verbalizations was correlated with more accepted bites (p = .02) and a higher rate of acceptance (p = .004). Conclusions During the course of offering a novel food, caregivers generally spoke more often with older infants and when children rejected the food. Caregivers appear to be more likely to employ verbal strategies to coax the acceptance of a food when children are reluctant to eat, rather than proactively engaging children throughout the feeding interaction. Furthermore, the nature and tone of caregiver verbalizations during feeding interactions may change over the course of the feeding session with positive verbalizations waning and the use of negative and neutral prompts increasing if children show reluctance to consume the food. Funding Sources The Sugar Association.

Ecology-guided prediction of cross-feeding interactions in the human gut microbiome

Understanding a complex microbial ecosystem such as the human gut microbiome requires information about both microbial species and the metabolites they produce and secrete. These metabolites are exchanged via a large network of cross-feeding interactions, and are crucial for predicting the functional state of the microbiome. However, till date, we only have information for a part of this network, limited by experimental throughput. Here, we propose an ecology-based computational method, GutCP, using which we predict hundreds of new experimentally untested cross-feeding interactions in the human gut microbiome. GutCP utilizes a mechanistic model of the gut microbiome with the explicit exchange of metabolites and their effects on the growth of microbial species. To build GutCP, we combine metagenomic and metabolomic measurements from the gut microbiome with optimization techniques from machine learning. Close to 65% of the cross-feeding interactions predicted by GutCP are supported by evidence from genome annotations, which we provide for experimental testing. Our method has the potential to greatly improve existing models of the human gut microbiome, as well as our ability to predict the metabolic profile of the gut.

Extracellular Metabolism Sets the Table for Microbial Cross-Feeding

SUMMARY The transfer of nutrients between cells, or cross-feeding, is a ubiquitous feature of microbial communities with emergent properties that influence our health and orchestrate global biogeochemical cycles. Cross-feeding inevitably involves the externalization of molecules. Some of these molecules directly serve as cross-fed nutrients, while others can facilitate cross-feeding. Altogether, externalized molecules that promote cross-feeding are diverse in structure, ranging from small molecules to macromolecules. The functions of these molecules are equally diverse, encompassing waste products, enzymes, toxins, signaling molecules, biofilm components, and nutrients of high value to most microbes, including the producer cell. As diverse as the externalized and transferred molecules are the cross-feeding relationships that can be derived from them. Many cross-feeding relationships can be summarized as cooperative but are also subject to exploitation. Even those relationships that appear to be cooperative exhibit some level of competition between partners. In this review, we summarize the major types of actively secreted, passively excreted, and directly transferred molecules that either form the basis of cross-feeding relationships or facilitate them. Drawing on examples from both natural and synthetic communities, we explore how the interplay between microbial physiology, environmental parameters, and the diverse functional attributes of extracellular molecules can influence cross-feeding dynamics. Though microbial cross-feeding interactions represent a burgeoning field of interest, we may have only begun to scratch the surface.