Live weight gain and urinary nitrogen excretion of dairy heifers grazing pasture, chicory and plantain

The objective of this study was to determine the effect of feeding plantain and chicory at different proportions in the diet with perennial ryegrass-white clover pasture on the live weight (LW) gain, urinary nitrogen (N) excretion, and urination behaviour of dairy heifers grazing in autumn. The study was completed at Lincoln University’s Ashley Dene Pastoral Systems Research Farm, Canterbury, New Zealand and had a duration of 32 d in autumn. A total of 60 Friesian x Jersey dairy heifers aged 8-9 months, were blocked into five dietary treatments balanced for their LW and breeding worth; 100% perennial ryegrass-white clover pasture (R; n = 12); 50% pasture + 50% chicory (50%C; n = 10); 75% pasture + 25% chicory (25%C; n=12); 50% pasture + 50% plantain (50%P; n = 12); and 75% pasture + 25% plantain (25%P; n=12). A fresh allocation of the herbage was offered every 3 d with herbage allowance calculated according to feed requirement for maintenance plus gain of 1.0 kg LW/d. The results showed no significant difference in LW gain between treatments (mean = 0.70 kg/d/hf; P = 0.11). There was no significant difference in urine N, NH3, BUN, glucose, urea, faecal DM and microbial protein synthesis between all treatments (P>0.05). Allantoin was significantly lower in R and 25%P (2.45mmol/L and 2.43mmol/L respectively) and higher in 25%C (4.17mmol/L) (P=0.029). Uric acid was significantly lower in R and 25%P (0.17mmol/L and 0.16mmolL respectively) and higher in 25%C (0.28mmol/L) (P =0.033). A small difference was apparent in creatinine, where R and 25%P were lower (0.75mmol/L and 0.78mmo/L) and 25%C was higher (1.18mmol/L) (P=0.07). A significantly higher urination frequency was observed in R and a significantly lower urination frequency in 50%C (5.91 urination/hf/6h and 2.33 urinations/hf/6h respectively; p-value