Identifying valid indicators to assess animals' emotional states is a critical objective of animal welfare science. In horses, eye wrinkles above the eyeball have been shown to be affected by pain and other emotional states. From other species we know that individual characteristics, e.g., age in humans, affect facial wrinkles, but it has not yet been investigated whether eye wrinkle expression in horses is systematically affected by such characteristics. Therefore, the aim of this study was to assess how age, sex, breed type, body condition, and coat colour affect the expression and/or the assessment of eye wrinkles in horses. To this end, we adapted the eye wrinkle assessment scale from Hintze et al. ( 1 ) and assessed eye wrinkle expression in pictures taken from the left and the right eye of 181 horses in a presumably neutral situation, using five outcome measures: a qualitative first impression reflecting how worried the horse is perceived by humans, the extent to which the brow is raised, the number of wrinkles, their markedness and the angle between a line through both corners of the eye and the topmost wrinkle. All measures could be assessed highly reliable with respect to intra- and inter-observer agreement. Breed type affected the width of the angle [ F (2,114) = 8.20, p < 0.001], with thoroughbreds having the narrowest angle ( M = 23.80, SD = 1.60), followed by warmbloods ( M = 28.00, SD = 0.60), and coldbloods ( M = 31.00, SD = 0.90). None of the other characteristics affected any of the outcome measures, and eye wrinkle expression did not differ between the left and the right eye area (all p -values > 0.05). In conclusion, horses' eye wrinkle expression and its assessment in neutral situations was not systematically affected by the investigated characteristics, except for “breed type”, which accounted for some variation in “angle”; how much eye wrinkle expression is affected by emotion or perhaps mood needs further investigation and validation.
This study examined enteric and excreta emissions from cattle and pigs with a focus on effects of changed feeding practices. We assessed the impact of a revision of the Austrian Greenhouse Gas and Air Pollutant Inventory (national method, NM), i.e., the implementation of the Tier2-method of the IPCC-2019 guidelines, to a more dynamic integration of past and present feeding practices. Cattle—in particular, dairy cows—had the highest contribution to enteric CH4 emissions and to nitrogen (Nex) and volatile-solid (VSex) excretion, independent of the assessment method (NM or IPCC-2019). These emissions as well as excreta quantities are directly associated with feeding. The most relevant changes from implementing IPCC-2019 were (i) reduced enteric CH4 over the entire time series and (ii) increased Nex and VSex, especially for the period from 1990 to 2005. Additionally, uncertainties in the emissions and excreta were analyzed and related to the quantities of protein consumed. From 1990 to 2020, favorable trends per unit of protein were shown due to increased performance and concomitantly reduced animal numbers. The changes were especially pronounced for CH4, Nex, and VSex from dairy cows (−40% to −46%) but also substantial for other cattle (−26% to −31%), breeding pigs (−12% to −28%), and partially growing-fattening pigs (−3% to −20%). Future mitigation potential may result from reduced dietary crude-protein content, especially in pigs, and the use of feed additives. Feed additives for ruminants with enteric CH4-mitigating effects showed a particularly high reduction potential for the total amount of greenhouse gases from the livestock sector.
Identifying and validating behavioral indicators of mood are important for the assessment of animal welfare. Here, we investigated whether horses' eye wrinkle expression in a presumably neutral situation is a measure of mood as assessed in a cognitive judgment bias task (JBT). To this end, we scored pictures of the left and right eyes of 16 stallions for different aspects of eye wrinkle expression and tested the same individuals on a spatial JBT with active trial initiation. Eye wrinkle expressions were assessed by a qualitative assessment, i.e., the overall assessment of how “worried” horses look, the number of wrinkles, and the angle measured at the intersection of lines drawn through the eyeball and the topmost wrinkle. Correlations between the three eye wrinkle measures and the optimism index as a measure of horses' decisions in the JBT were not statistically significant, but with increasing optimism index, horses tended to be scored as looking less worried (qualitative assessment). We discuss our findings from different perspectives and make suggestions for future research, e.g., by calling for experimental induction of mood and thus greater variation within and/or between individuals and by investigating the interplay between shorter-lasting emotional and longer-lasting mood states to further explore the potential use of the JBT to validate eye wrinkles and other facial or body expressions as indicators of mood.
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