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This Article Full Text (PDF) All Versions of this Article: jas.2008-1461v1 87/7/2291    most recent Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Muhonen, S. Articles by Jansson, A. Search for Related Content PubMed PubMed Citation Articles by Muhonen, S. Articles by Jansson, A.

Effects on the equine colon ecosystem of grass silage and haylage diets after an abrupt change from hay

S. Muhonen, V. Julliand^*, J. E. Lindberg, J. Bertilsson and A. Jansson

Dept of Animal Nutrition and Management, Swedish University of Agricultural Sciences, S-75007 Uppsala, Sweden ^* Etablissement National d’Enseignement Supérieur Agronomique de Dijon (ENESAD), 21079 Dijon, France

Sara.Muhonen{at}huv.slu.se

Abstract

The objective of this study was to investigate the effect of an abrupt change from grass hay (81% DM) to grass silage (36% DM) or grass haylage (55% DM), fed at similar DM intakes, and to compare the effects of silage and haylage on the composition and activities of the colon microflora. The forages were from the same swath harvested on the same day. Four adult colon-fistulated geldings were randomly assigned to diets in a cross-over design. The study started with a preperiod when all 4 horses received the hay diet, followed by an abrupt feed change to the haylage diet for 2 horses and the silage diet for 2 horses. All 4 horses then had a new second preperiod of hay, followed by an abrupt feed change to the opposite haylage and silage diet. The periods were 21 d long and the forage-only diets were supplemented with minerals and salt. The abrupt feed changes were made at 0800 . Colon samples were taken before the abrupt feed change, 4 and 28 h after the feed change, and 8, 15, and 21 d after the feed change, all at 1200. Colon bacterial counts, VFA, pH and DM concentrations were unchanged throughout the first 28 h after the abrupt feed change from hay to haylage and silage. Also, fecal pH and DM concentrations were unchanged during the first 28 h. During the weekly observations colon lactobacilli counts increased (P = 0.023) in horses receiving the silage diet and were greater than on the haylage diet at 21 d. Streptococci counts decreased (P = 0.046) in horses receiving the haylage diet and were lower than on the silage diet at 15 and 21 d. Total VFA concentrations and colon and fecal pH did not differ between diets and were unchanged throughout the weekly observations. The DM concentration of colon digesta and feces decreased (P = 0.030 and 0.049, respectively) on both diets during the weekly observations. The results suggest that in horses fed at the maintenance level of energy intake, an abrupt feed change from grass hay to grass silage or grass haylage from the same crop does not induce any major alterations in the colon ecosystem during the first 28 h. During the subsequent 3 wk period, colon and fecal DM decreased and there were alterations in the lactobacilli and streptococci bacterial counts. The changes in lactobacilli and streptococci counts need further investigation.

Key Words: colon microflora • equine • forage • haylage • silage • water intake