Abstract
Forty five Soviet Chinchilla rabbits weaned at 35 d of age were fed 5 experimental diets prepared by using oat plant meal ($T_2,\;T_4$) and tall fescue hay ($T_3,\;T_5$) at 25% and 50% level along with control ($T_1$). The gain in body weight at 84 d of age decreased with test material substitution, however, the differences were non significant when compared with oat plant meal and were significant (p<0.05) with tall fescue hay at both the levels. Feed conversion ratio also deteriorated with test material and its increasing proportion and the differences were significant (p<0.05). The performance-index calculated were 42.1, 36.7, 29.4, 33.3 and 18.8 in $T_1,\;T_2,\;T_3,\;T_4$ and $T_5$, respectively. Digestibility of all the organic nutrients decreased significantly (p<0.05) with test material incorporation, as a result nutritive value of the test diets decreased linearly. Nitrogen balance as per cent of intake was higher in oat plant meal substituted diet compared to tall fescue substituted diet. Cost per kg live weight gain was lowest with 50% oat plant meal followed by 25% oat plant meal incorporation. It was highest with tall fescue hay substitution. Nutritive value of oat plant meal as calculated was DCP 5.1%, TDN 35.8% and that of tall fescue hay was DCP 6.5%, TDN 30.8%. Thus, oat plant meal can be substituted safely up to 25% in the feeding regime of weaner rabbits whereas, for tall fescue hay the safe limit is below 25% level and needs to be ascertained.