Effect of particle size of paddy straw on physical characteristics and performance of lambs fed paddy straw based complete diets

Three complete diets were formulated and processed into mash using paddy (Oryza sativa) straw ground through 8, 12 and 16 mm sieve as sole source of roughage at 35% level and were compared with conventional diet (concentrate mixture and chopped jowar straw, fed separately). The four diets were fed to 32 growing Deccani lambs (3–4 months) divided into four equal groups. Incorporating 8 mm or 12 mm ground paddy straw in complete diets (8PS and 12PS, respectively) increased the bulk density by 56.06 and 10.81 per cent, respectively, compared to complete diet with 16 mm (16PS) paddy straw. The average particle size of paddy straw ground through 16, 12 and 8 mm sieve was 1995.3, 1445.4 and 1202.3 m, respectively. Complete diet 16PS had more coarse (60%) and less medium and fine (40%) particle compared to other two complete diets. Complete diet 8PS had only 30% coarse particle due to fine grinding of paddy straw. The modulus of fineness of complete diet increased from 3.34 to 4.80 as the size of screen increased from 8 to 16 mm. Similarly, the average particle size in complete diets increased from 912.1 to 1687.3 with increase in screen size from 8 to 16 mm. The ADG of lambs fed complete diets 8PS and 12PS was higher (P<0.01) compared to those fed conventional diet. The nutrient efficiency was higher (P<0.01) in complete diets compared to conventional diet. It was concluded that grinding of paddy straw with 8 mm or 12 mm sieve were optimum for inclusion in complete diet in order to obtain higher growth rate in lambs. Complete diet system was economical and resulted in higher performance compared to conventional system of feeding in Deccani sheep.