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A ruminant's early experience with low-quality food (LQF) is expected to increase its acceptance and preference in adulthood. Contrarily, we found that experienced sheep (ES) exposed to mature oat hay early in life ate less of this LQF than inexperienced sheep (IS). A possibility is that ES might have devaluated the LQF through continuous comparisons against high-quality food (HQF) supplements (sunflower meal and ground corn) that were simultaneously available during early experience. In this study, we tested the devaluation hypothesis with a successive negative contrast (SNC) procedure. In a consummatory SNC procedure, 'shift' subjects are unexpectedly changed from HQF to LQF, and their consumption is then compared against the consumption of 'unshift' subjects that receive LQF all throughout the SNC procedure. The magnitude of the difference in consumption between preshift and postshift is regarded as a measure of the degree to which both foods (HQF and LQF) are perceived to differ hedonically. When sheep from our previous study were 300 days old, both ES and IS were randomly assigned to either shift (ES-S and IS-S) or unshift conditions (ES-U and IS-U; n 5 6 in each group). Groups ES-S and IS-S were fed HQF (alfalfa hay) during the preshift phase, and then suddenly changed to LQF (oat hay) in the postshift phase. Groups ES-U and IS-U (controls) were fed only LQF throughout the SNC procedure. Subjects in ES-S showed a significantly lower intake of LQF than those in ES-U in the first postshift session (i.e. they showed an SNC effect), which was not observed in IS. These results agree with ES subjects having devalued LQF during early experience. We discuss the possibility that high levels of nutrient supplementation can result in devaluation of LQF (i.e. decrease in preference and acceptance), whereas restricted levels of supplementation may promote a positive experience with LQF.Keywords: early experience, food valuation, low-quality food, sheep, successive negative contrast ImplicationsEarly experience with specific foods can improve their acceptance and preference later in life. However, our past and present results with sheep suggest that mere exposure to foods in early life may not be sufficient to attain that outcome. Behaviour towards a food source and learning about its consequences depend not only on the food's intrinsic properties but also on the alimentary context in which it is presented. Current results can be interpreted as showing that the use of high levels of nutrient supplementation can cause a negative experience with LQF (i.e. a decrease in the preference and acceptance), whereas restricted levels of supplementation (a more typical scenario) may promote the opposite result (i.e. enhanced experience with LQF). IntroductionEarly food experience has the potential to increase food acceptance (voluntary intake of a given food) and preference (choices among food alternatives) in ruminants (Provenza and Balph, 1987;Distel and Provenza, 1991;Distel et al., 1994). Moreover, preference for low-quality f...

Serenity has been defined as a positive emotion that reflects feelings of inner peace and confidence. The development of serenity constitutes a valuable resource that enables children to cope with life stressors and to establish positive relationships with others. The present study examined serenity and possible gender group differences in Argentinean children. The second goal was to investigate the relation between serenity and prosocial and aggressive behaviors. Participants were 615 children aged 9 to 13 years (276 boys, 339 girls), from 11 public primary schools in the city of Buenos Aires, Argentina. Gender analyses showed no differences between boys and girls in serenity scores. As expected, serenity proved to be positively related to prosocial behaviors and negatively related to physical and verbal aggression. These results indicate that children who describe themselves as more serene are also prone to give help and comfort to others. Moreover, serene children appear to be less aggressive towards classmates. Evidence suggests that peer relations can be enhanced by the utilization of serenity skills in the school context.

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Acceptance of and preference for a particular food depends not only on its intrinsic (e.g. nutritional) properties but also on expected or recent food experiences. An instance of this type of phenomenon has been called induction effect, which consists of an increased intake of a type of food when it precedes a hedonically preferred food in a sequence familiar to the animal, relative to controls that have access only to the less-preferred food. The purpose of our study was to assess intake induction of a low-nutritious food when followed by different high-nutritious supplements in sheep (Ovis aries). In this experiment, we ran a supplemented phase where animals fed oat hay (a low-nutritious food) in the first part of the daily feeding sessions followed by a supplement with either a high (soya bean meal; group GS) or a low (ground corn; group GC) protein-energy ratio in the second part ate more oat hay than controls that were fed oat hay in both parts of sessions (group GH). In addition, supplemented animals presented a stronger preference for oat hay over alfalfa hay than controls in a subsequent choice. When all animals received no food in the second part of the sessions (Non-supplemented phase), intake of oat hay converged to the control's intake level in all the groups, suggesting that the presence of supplements after access to oat hay was responsible for intake induction. Lastly, we repeated the supplemented phase with a different control group where animals received oat hay in the first part of the sessions and no food in the second part (group NF), thus equalizing groups in terms of the time of access to oat hay in a session. Groups GS and GC still developed higher intake of oat hay than group NF. In both supplemented phases of the experiment, we estimated animals' daily metabolizable energy (ME) and crude protein (CP) intake. CP intake was higher in group GS than in groups GC, GH and NF, but there was no difference between group GC and the controls. In turn, groups did not differ in ME intake in the First supplemented phase, and only group GS presented higher ME intake than the rest of the groups in the Second supplemented phase. Therefore, a nutritional account of the present induction effect seems insufficient. We propose that a learned association between oat hay and the post-ingestive feedback from the subsequent high-nutritious supplements underlay sheep's intake induction and increased preference for oat hay.

Las emociones positivas constituyen una de las principales vías de acceso al bienestar psicológico, ya que favorecen el desarrollo de recursos que robustecen la capacidad de sobreponerse a la adversidad y de manejar con éxito diferentes situaciones de la vida. El presente trabajo aborda la medición de una emoción positiva de gran relevancia para el campo de la salud mental y la educación. El propósito principal fue construir y analizar el funcionamiento psicométrico de dos escalas independientes para evaluar la serenidad en niños argentinos: una técnica de autoinforme y un reporte de observador externo. Se llevó a cabo un estudio de tipo instrumental, con diferentes muestras de niños, seleccionadas para la autoevaluación y la heteroevaluación, a fin de analizar el poder discriminativo de los ítems, la consistencia interna, la validez de constructo y la validez nomológica de las escalas. En ambos casos, los resultados indicaron que los ítems tienen una adecuada capacidad discriminante, una consistencia interna alta, y se agrupan de manera clara en un único factor general. Asimismo, muestran evidencias de validez nomológica, ya que los niños con altas puntuaciones de serenidad tendrían menor probabilidad de mostrar comportamientos agresivos cuando se relacionan con sus compañeros, mostrarían menos hiperactividad y un menor número de reacciones impulsivas. A partir de los resultados, se concluye que las nuevas escalas de serenidad infantil constituyen un aporte interesante para el campo de la evaluación psicológica, ya que proveen datos confiables y válidos sobre una emoción positiva que ha sido escasamente estudiada en el período de la niñez.

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