Effect of processing cotton straw based complete diet with expander-extruder on performance of crossbred calves

A growth trial of 180 days was conducted on 18 crossbred calves (6-9 months, 73.48 +/- 6.52 kg) by randomly allotting to two complete diets and a conventional diet (6 in each group). The complete diets were formulated containing 40 per cent cotton straw, one processed in mash form and other subjected to expander-extruder pelletization (EEP). These two complete diets were compared with conventional system of feeding under which concentrate mixture and cotton straw were fed separately in a 60:40 ratio. The calves on EEP complete diet consumed more (p<0.01) DM in comparison to other two groups. The DMI per 100 kg body weight was similar among all the diets. The ADG was significantly (p<0.01) higher in calves fed EEP complete diets (815.4 g) followed by mash (627.0 g) in comparison to conventional diet (464.9 g). The DM intake per kg metabolic body weight was higher (p<0.01) on complete diet than conventional diet. The intakes of DCP (p<0.05), TDN (p<0.01), and ME (p<0.01) per kg metabolic body weight were significantly higher on EEP complete diet in comparison to mash and conventional diet. The water intake per kg DM intake was comparable among all the diets. The efficiency of DM utilisation was higher p (<0.05) on EEP complete diet (5.84) in comparison to conventional diet (7.41), whereas on mash diet it was intermediate (6.68). The efficiency of DCP utilization was similar in mash and EEP complete diet fed groups, which was higher (p<0.05) than that of the conventional diet. Expander-extrusion though increased the cost of production it reduced the cost of feed per unit live weight gain by 12.28% in comparison to its mash form and by 16.76% when concentrate and cotton straw were fed separately. The results indicated that blending of cotton straw along with concentrates in a complete diet increased the palatability of the straw in comparison to conventional system and expander extruder processing of cotton straw based complete diet gave better growth performance and may form an economic ration for growing crossbred calves.