Relationships between early experience to dietary diversity, acceptance of novel flavors, and open field behavior in sheep

VILLALBA, J.J.; CATANESE, F.; DISTEL, R.A.

PHYSIOLOGY AND BEHAVIOR

PERGAMON-ELSEVIER SCIENCE LTD

Año: 2011 vol. 105 p. 181 - 187

0031-9384

<!-- /* Font Definitions */ @font-face {font-family:NewCenturySchlbk-Roman; panose-1:0 0 0 0 0 0 0 0 0 0; mso-font-alt:Cambria; mso-font-charset:0; mso-generic-font-family:roman; mso-font-format:other; mso-font-pitch:auto; mso-font-signature:3 0 0 0 1 0;} /* Style Definitions */ p.MsoNormal, li.MsoNormal, div.MsoNormal {mso-style-parent:""; margin:0cm; margin-bottom:.0001pt; mso-pagination:widow-orphan; mso-layout-grid-align:none; text-autospace:none; font-size:12.0pt; font-family:NewCenturySchlbk-Roman; mso-fareast-font-family:"Times New Roman"; mso-bidi-font-family:NewCenturySchlbk-Roman; mso-ansi-language:EN-US; mso-fareast-language:EN-US;} @page Section1 {size:612.0pt 792.0pt; margin:70.85pt 3.0cm 70.85pt 3.0cm; mso-header-margin:36.0pt; mso-footer-margin:36.0pt; mso-paper-source:0;} div.Section1 {page:Section1;} --> This study determined whether early experiences by sheep to monotonous or diverse diets influence plasmatic profiles of cortisol, a hormone involved in stress responses by mammals, and if those experiences influence the link between general fearfulness and response to separation – as measured by the open field test (OFT) and stress induced hyperthermia (SIH) – and the readiness to eat new foods in a new environment. Thirty, 2-mo-old lambs were randomly assigned to 3 treatments (10 lambs/treatment). Lambs in one treatment (Diversity) received in successive periods of exposure all possible 4-way choice combinations of 2 feeds high in energy and 2 feeds high in protein from an array of 6 feeds: 3 high in energy (beet pulp, oat grain, and a mix of grape pomace:milo [XX:XX] and 3 high in protein (soybean meal, alfalfa, corn gluten meal). Lambs in the Diversity+Toxin treatment received the same exposure described for Diversity but two phytochemicals, oxalic acid (XX%) and quebracho tannins (XX%) were randomly added within any period of exposure to one feed high in energy and one feed high in protein. Lambs in the treatment Monotonony received a monotonous balanced ration containing all 6 feeds used in Diversity Diversity+toxin throughout the study. After exposure, lambs were offered a choice of the aforementioned 6 feeds (Diversity, Diversity+Toxin) or the monotonous diet (Monotony), bled 1, 2, and 3 h post-feeding and subjected to an ACTH challenge test. After washout periods when all lambs were fed the same diets, we assessed reluctance to eat novel flavored foods (onion-, coconut- and cinnamon-flavored wheat bran), open field behavior, and SIH in all groups. Lambs in Monotony showed greater concentrations of plasma cortisol 1 h post feeding than lambs in the Diversity or Diversity+Toxin groups (P = 0.041). Lambs in Diversity consumed more onion-flavored wheat bran (P = 0.05) than lambs in Monotony. Lambs Diversity also showed a greater cumulative consumption of all flavors on day 2 than lambs in Monotony (group x day; P = 0.01; Figure 2). Lambs in Diversity showed lower increase in rectal temperature (P = 0.07) and tended to manifest a lower number of lines crossed (P = 0.11) than lambs in Monotony. Lambs in the Diversity group exhibited a positive relationship between consumption of cinnamon-flavored wheat bran and: 1) attempts of escape (r = 0.60; P =0.10) and 2) changes in rectal temperature (r=0.87; P = 0.16). Our results suggest that exposure to diverse foods early in life may be less stressful than exposure to monotonous rations, as measured by plasma cortisol concentrations after food ingestion, and by changes in rectal temperature and ambulation scores after exposure to OFT. Reluctance to ingest new foods in a new environment may be also influenced by early exposure to diverse or monotonous feeds.