EFFECT OF FORAGE HYDRATION ON LAG TIME DURING IN-VITRO DIGESTION OF MEADOW HAY

Digestion of plant cell wall has been observed to be a first-order pro cess with an initial lag. Lag is defined as the period of time immedia tely after forage is exposed to the fermentive environment during whic h digestion does not occur or occurs at a greatly reduced rate. The ef fects of forage hydration on lag were investigated by focusing on the first 20 h of in vitro digestion of meadow hay. Samples were hydrated for 0, 1, and 16 h before fermentation. Digestion kinetics was estimat ed by both a first-order kinetics model (KM) and an increasing relativ e-rate model (RRM). Model parameters were obtained using a non-linear least-squares procedure. The effect of forage hydration was significan t, especially for the 16-h treatment. The RRM produced a better fit fo r the data from each treatment, and a better fit was obtained when eac h data set was analysed separately.