PREDICTION OF THE NUTRITIVE-VALUE OF LUCERNE HAY IN DIETS FOR GROWINGRABBITS

Fifty-one New Zealand White X Californian rabbits were used to evaluat e apparent in vivo dry matter (DM), organic matter (OM), energy, nitro gen (N), neutral detergent fibre (NDF) and amino acid digestibilities of five lucerne hays varying in chemical composition. Hays were ground and pelleted and given as sole feeds throughout the experiment, In vi tro DM, OM, NDF and N digestibilities of feed samples were also determ ined. A ruminal incubation trial was performed to determine NDF disapp earance of lucerne hays in nylon bags. The type of lucerne hay had a l arge effect on its nutritive value. The range of variation for digesti ble energy (DE) and digestible crude protein (CP) contents and for NDF digestibility was 6.4-9.2 kJ g(-1), 114-164 g kg(-1) and 0.204-0.276, respectively. The type of lucerne hay also affected lysine, methionin e and threonine digestibilities. Stepwise regression analysis showed t hat the best single predictors for energy, CP, NDF and amino acid dige stibilities were dietary NDF and non starch polysaccharide (NSP) conte nts, ruminal NDF degradability after 48 h of incubation and CP digesti bility, respectively. Regressions using only chemical components as in dependent variables were also calculated, The results of this study sh owed that in vitro methods and prediction equations determined for mix ed diets and concentrated ingredients need to be adjusted to estimate nutritive value of forages in rabbits.