Ingestion d'herbe au pâturage par le cheval de selle en croissance : effet de l'âge des poulains et de la biomasse d'herbe

Abstract

Grass intake by growing horses at pasture: a test of the effects of the horses' age and sward biomass. No data are currently available on the quantities of food ingested by young horses at pasture, in spite of the fact that pasture constitutes the main source of nutrients for these animals. In this study, three levels of sward mass were offered to animals (2.3; 2.9 and 3.5 T DM .ha -1 ), which correspond to grass heights of 6.6, 8.1 and 9.4 cm. Horses of the Cheval de Selle Francais breed were used (1 and 2 years old, live weight of 334 and 478 kg respectively) in a latin square design. The daily quantities of grass ingested at pasture were determined, and relationships between daily intake, and the characteristics of the pasture and animal were studied. Intake relative to metabolic live weight did not vary between yearlings and 2-year-old horses. Intake averaged 82 g OM .kg -1 LW 0.75.d -1 . Compared with yearlings, 2-year-old horses had a lower daily foraging time and a higher intake rate (9.9 vs. 7.6 g OM .min -1 ). Grass height had no effect on the food intake of growing horses for grass between 6 and 9 cm high. Compared with cattle and even sheep, horses maintain their lev- els of food intake even at low sward heights. horse / feeding / grass / intake Resume — Alors que le pâturage constitue l'alimentation principale des jeunes chevaux, il n'existe que tres peu de donnees sur les quantites d'herbe ingerees sur les prairies. Dans cette experimenta- tion, trois niveaux de biomasse relativement faibles ont ete proposes aux animaux (respectivement 2,3 ; 2,9 et 3,5 T MS.ha -1 ), ce qui correspond a des hauteurs d'herbe de 6,6 ; 8,1 et 9,4 cm respectivement. Deux categories de poulains de selle (un an et deux ans, respectivement 334 and 478 kg) ont ete integrees a l'etude. L'essai a ete conduit selon un dispositif en carre latin 3 〈 3. Les quantites d'herbe