Kudzu (Pueraria montana var. lobata) age variability effects on total and nutrient-specific in situ rumen degradation

Early and late season kudzu leaves were collected to analyse dry matter (DM), crude protein (CP), acid detergent fibre (ADF), and neutral detergent fibre (NDF) in situ rumen disappearance to assess kudzu quality. Four studies were conducted during different growing periods [2 repeated early season (ES); 2 repeated late season (LS)] to determine age variability effects. Kudzu was incubated in the rumen between 0.25 and 72 h to determine total rumen degradation (%) and the rate of disappearance (% h(-1)). Data were analysed as a randomized complete block design (RCBD) with repeated measures. Regression analysis was used to determine the degradation rate. Overall season effects (across incubation times) for dry matter disappearance (DMD) were significantly different (P < .0001). There were also significant season by incubation time interactions for DMD. Rumen degradation rate was determined to be 2.41% h(-1) across both seasons, with no significant seasonal difference (P = .3396). Results from this study are indicative that ES kudzu is more degradable than LS. Although there are significant seasonal effects on kudzu DMD during certain incubation times, DMD overall for ES and LS is still indicative of high rumen degradability.