Indian Journal of Animal Research

Although crop residues rich in lignocellulose are a potential source of energy, their utilization is limited due to lack of lignolytic activity of the rumen microbial population. Feed processing by heat treatment is known to break the ligno-cellulolse complexes, in which extrusion has been reported as one of the best processing techniques to improve the nutritional value and efficient utilization of complete diets. A comparative evaluation of extruded complete feed based on finger millet straw, a conventional crop residue, along with areca sheath and maize cob has been taken up in this study.

The extruded complete feed was prepared using roughage and concentrate at proportion of 40:60, respectively. Twenty four Mandya lambs of about 3 to 4 months of age with body weight ranging from 7.8 to 12.9 kg were divided into three groups of eight each in a completely randomized design. Feeding trial was carried out for 12 weeks. The animals were randomly assigned to one of the treatment groups viz., T₁ (Finger millet straw based extruded complete feed), T₂ (Areca sheath based extruded complete feed) and T₃ (Maize cob based extruded complete feed). Digestion trial was conducted using 5 animals in each group during the last week of the growth trial.

Analysis of chemical composition (%) revealed that, maize cob and areca sheath were comparable with finger millet straw except that the maize cob contained lower total ash (2.52 v/s 8.61) and higher NDF and hemicellulose content (86.66 v/s71.61; 29.79 v/s17.18). Rumen in vitro net gas (ml/200 mg DM/24 h) production and energy density (ME MJ / kg DM) was higher in areca sheath and maize cob as compared to finger millet straw. There was significant difference in total DMI (g/d and g/kgW^0.75) among the treatment groups (P≤0.05). There was also a significant difference in OM, CP, EE and ADF intake (P≤0.05). The ADG (g) and FCR (g DMI/ g BW gain) for T₁, T₂ and T₃ groups were statistically non-significant. The mean apparent digestibility (%) of DM, OM, CP, NDF and ADF was significantly different among the treatment groups (P≤0.01). The per cent digestible organic matter in dry matter (DOMDM) (T₁:70.89,T₂:76.13and T₃:63.33) was also significantly different among the treatments (P≤0.01). It was concluded that the growth rate of lambs fed finger millet straw, areca sheath and maize cob based extruded complete feeds was comparable and could be utilized to sustain production performance of growing Mandya lambs.