Almost three decades ago, the dietary fibre hypothesis emergedamongst researchers working on the relation-ships between the diet and incidence of chronic diseases. Historically the emphasis of research on fibre has concentrated on the efiect of fibre in relation to the alllount rather than the type present in the diet. Then, more and more compre-hensive studies have been carried out combining in vitro, animal and human experiments. Cottonseed hulls are a by-product of cotton processing, containing a large proportion of neutral detergent fibre (NOF) and associated lignin. and have been considered as a useful non-forage fibre source in ruminant rations (Hall and Akinyode. 2000). Results of previous in vitro studies have revealed that sodium hydroxide treatment of fibrous feedstulTs can improve dry matter (DM) or NDF digestibility of them. Cotlonseed hulls have various physicochemical characteristics. There are a few investigations which have been accomplished, covering the physicochemical characteristics of the respect by-product. The objectivc of this study was to determine the physicochemical and chemical characteristics, and in vitro gas production parameters of chemically treated Cotlonseed hulls (CH). In this study, cottonseed hulls were treated with NaOH as 20 glkg DM [a 20% solution ofNaOH was sprayed on CH and kept for 0.5 h (CH2S0.5) or 48 h (CH2S48)] or 40 glkg DM [a 40% solution of NaOH was sprayed on CH and kept for 0.5 h (CH4S0.5) or 48 h (CH4S48) at room temperature]. Some of the physicochemi:al characteristics of CH are % 5.4. % 75. % 65, % 1.6 and % 3.1 for crude protein. neutral detergent fiber, acid detergent fibe\\\', ether extract and ash, respectively. A gas production test was conducted to determine the gas production ,Jarameters using chemically treated CH. Gas production parameters of non-treated or chemically treated CH are sho\\\\\\\\.n in Table I. Data were analyzed by feed-plot program based on the model of P= b (I - e .c\\\'), where P = amount of produced gas in time, b = gas production from femlentable fraction and c = fractional constant rate of gas production. There is no significant difference between gas production parameters of non-treated or chemically treated CH.

Keywords