Nutritional evaluation of spent maize (Zea mays) cobs as roughage source in sheep feeding

A study was conducted to compare the conventional finger millet (Eleucine coracana) strawbased diet (T₁) with urea and salt-treated (1% each, w/w) maize (Zea mays) cob-based diet (T₂) on the growth performance of lambs. Sixteen Bannur lambs (3 to 5 months-old, body weight ranging from 8 to 15 kg) were divided into two groups of eight each in a completely randomized design. Twelve weeks feeding trial was carried out with an initial adjustment period of one week and six days of digestion trial at the end of the experiment. Chemical analyses revealed that maize cob was comparable with finger millet straw except for lower crude protein (4.10 vs 2.61%) and higher neutral detergent fibre (NDF) and acid detergent lignin (ADL) (64.25 v/s 80.88%; 2.73 vs 6.78%). Cumulative gas (ml/200mg DM/24 h) production and energy density (ME MJ/kg DM) was higher in urea treated maize cob (41.68 and 7.88) as compared to untreated maize cob (37.37 and 7.33) or finger millet straw (36.76 and 7.19). There was significant (P<0.05) difference in total dry matter (DM) intake between the treatment groups (T¹: 401 and T²: 319 g/d). Significant (P<0.05) difference was also observed in the overall organic matter (OM), neutral detergent fibre and acid detergent fibre (ADF) intake between the treatment groups. The average daily gain (g/day) and feed conversion ratio (g DMI/g body weight gain) for T 1 and T 2 groups was statistically nonsignificant (T¹: 31.55 and 12.71; T²: 39.29 and 8.12). The mean apparent digestibility of nutrients (DM, OM, ether extract and NDF) was comparable between the treatment groups except for ADF. The digestible OM on DM basis (%) between the treatment groups was also comparable. It was concluded that, urea-treated maize cobs can be utilized as roughage source for feeding small ruminants during the periods of scarcity.