INFLUENCE OF THE PHYSICAL FORM OF FEEDS A ND OF THE TIME OF FEEDING CONCENTRATE ON PLASMA-CONCENTRATIONS OF AMINO-ACIDS IN PONIES FED STRAWAND CONCENTRATE DIETS

A diet consisting of molassed straw (68%) and concentrate (25% maize a nd 7% soya-bean meal) was fed to achieve INRA recommandations for main tenance. In a first experiment, E1, a 2 x 2 crossover design was used with eight adult male ponies (average weight 202 kg) to compare two di fferent diets: R I: pelleted concentrate and molassed straw fed simult aneously (at 8 00 and 16 00 hours); R2: pelleted concentrate fed two h ours after the molassed straw (at 10 00 and 18 00 hours). In a second experiment E2, a 3 x 3 latin square design was used with nine adult ma le ponies (average weight 198 kg) to compare three different diets: R3 : combined concentrate and molassed straw pellets (fed at 8.00 and 16 00 hours); R4: pelleted concentrate and pelleted molassed straw fed si multaneously (at 8. 00 and 16 00 hours); R5: pelleted concentrate fed two hours after the pelleted straw (at 10.00 and 18.00 h). Samples of jugular blood were taken at 8 00 (T), 10 00 (T+2), 11 00 (T+3), 13 00 (T+5), 14 00 (T+6), 16 00 (T+8), 17 00 (T+9) hours, for determination of plasma free amino acids (PFAA). RI gave higher concentrations of to tal PFAA than R2. Daily average concentrations were 2 687 with RI and 2 484 mu mol/L with R2. Peak values were reached at T+2 with R1 (3 639 mu mol/L) and at T+6 with R2 (2 712 mu mol/L). in E2, daily average c oncentrations were higher with R5 (2 745 mu mol/L) than with R4 (3 443 mu mol/L) and R3 (2 608 mu mol/L). Peak values were reached at T+6 (3 087 mu mol/L), T+2 (3 443 mu mol/L) and T+2 (2 914 mu mol/L), respect ively. The positive effect on nitrogen digestion of feeding the concen trate after the straw seems to be affirmed, but could be less pronounc ed if the concentrate is pelleted