Abstract:
The effect of grazing of naturaltherbage by tethered heifers in a coconut plantation, on the growth and behaviour as well as on herbage and coconut production was examined during a six month period. The experiment was conducted in a coconut estate at Kotawila, Kamburugamuwa. There were four treatments namely coconut without fertilizer (T1); coconut + fertilizer (CRI recommended levels) (T2); heifers grazed herbage (T3); and heifers grazed natural herbage + tree fodder (kg/d) + concentrate supplement (250 g/d) (T4). The experiment design was a RCBD with 3 reps and the stocking rate was 2 heifers/ 0.4 ha. When considering the behaviour, heifers spent more time on resting, rumination, licking, scratching and lying when feed supplements (tree fodder and concentrate) were given. Vocalization, walking and grazing of upper layer were prominent with heifers when no supplements were given. Provision of tree fodder and concentrates improved the weight gain (T3 - 82.21 ± 63.03 versus T4 - 101.00± 57.10 g I day) of cattle even during a short period of time. The amount of dung deposited were 400 ± 28.25 and 386.3 ± 45.23 kg/palm/yr for T4 and T3, respectively while the amounts of urine deposited were 190.68 ± 29.58 and 182.46 ± 35.39 kg/palm/yr for T4 and T3, respectively. Herbage nitrogen content was also increased with supplementation while there was a significant reduction of N in un-supplemented treatment. Over grazing without supplements (T3) would hitve depleted the soil and herbage N, and thereby conservation of N through recirculation within the animal. The dry period would have been aggravated this condition by reducing the dung decomposition rate and increasing the urine evaporation rate. The results suggested that, supplementation of tree fodder; straw and low cost concentrate mixture to heifers grazed natural herbage under coconut showed beneficial effects on pasture growth, behaviour and live weight even during a short period of time. Further investigations would show the actual benefits with the passage oftime.
