Relating sensory characteristics with biochemical analyses of hays fed to horses

s / Journal of Equine Veterinary Science 33 (2013) 321-399 346 Nutrition: Oral Presentations Relating sensory characteristics with biochemical analyses of hays fed to horses S. Julliand , C. Omphalius , M. Orard , O. Parodi , C. Villot , H. Warren , and V. Julliand 4 1 Lab to Field, France, 2 AgroSupDijon, France, 3 Alltech Bioscience Centre, Ireland, 4 Uranie NCA, AgroSup Dijon, France Forages form the basis of horse diets. However in the field, forage nutritive value calculated from biochemical analyses is not commonly used. Horse people evaluate forage quality as “good” or “bad” based on their own quality indicators. The present study aimed at comparing the nutritive value of hays with their sensory characteristics using a descriptive analysis. Twenty hay buyers (equine breeders, trainers, owners and riding school proprietors) were interviewed. While trainers, owners and riding school proprietors said that they looked firstly at the origin of the hay, breeders focused on timing of harvest. All buyers looked at organoleptic qualities as the second major indicator. Among organoleptic qualities, odour and colour were the most frequent indicators mentioned.Twenty-one meadow hays originating from 12 different administrative regions of France were then collected for sensorial and biochemical analyses. For each hay, 2 kg were randomly hand-sampled from one opened bale in 10 different locations. Part was sent for biochemical analysis and part was used for sensorial analysis.The sensorial descriptive analysis was run in three separate workshops with 54 untrained subjects to sort hays by appearance, odour or texture. Subjects were asked to group hays by similarity of view, smell or touch and then to describe the groups with their own qualifying terms (with a maximum of five terms per group).Multidimensional scaling analyses were carried out in order to provide a hierarchical clustering of hays based on their description similarities and to map each group of hays in correlation with the associated description terms. Appearance was separated into four statistically distinct groups and described as “grassy-dark-green”, “mixedthin”, “heterogenic-medium”, “yellow-strawy-moldy”. Odour characteristics were also separated into four groups: “dry-smell of farm-persistent”, “sweet-pleasant”, “spicyaromatic-flowered”, “unpleasant-acid-moldy-smell of urine”. Texture characteristics were separated into three groups: “matted-long-pleasant-soft-homogeneous”, “un -pleasant-strawy”, “mix-short-lightened”.Hay digestible energy (DE) varied from 1.56 to 2.32 Mcal/kg DM and crude protein (CP) from 63 to 163 g/kg DM.The appearance “grassy-dark-green” group had a higher DE than the “yellow-strawy-moldy” group (p<0.05). Predictive energetic values for “yellow-strawy-moldy” hays were lower (p1⁄40.001) than for “grassy-dark-green” hays (1.7 versus 2.1 Mcal/kg DM, respectively).The odour “sweet-pleasant” group appeared higher than the “unpleasant-acid-moldysmell of urine” group with respect to DE (p<0.05). Predictive energetic values for hays that smell “sweetpleasant” were higher (p1⁄40.005) than for other hays (2.1 versus 1.8 Mcal/kg DM, respectively).No significant difference has been noticed for DE among the texture groups. Additionally, no significant difference in crude protein appeared among the groups.This study shows a link between appearance and odour of hays and their DE, which needs further investigation.