Effect of chemical treatment of barley straw on digestibility in sheep and goats

Abstract

The main object of the experiments described was to compare the digestibility in and acceptability to sheep and goats of barley straw and barley straw sprayed with sodium hydroxide (NaOH). In feeding trials involving six sheep and six goats, chopped untreated barley straw (US) was compared with straw chopped and spray treated with 5g NaOH in 60 ml solution per 100 g straw. The treated straw (TS) was neither washed nor neutralized. Both US and TS were fed to appetite to sheep and goats with protein, mineral and vitamin supplements and ad libitum water. The TS was readily consumed and there were no metabolic problems.

Dry Matter Intake (g/kg W.⁷⁵) was significantly increased (P<0.05) in sheep but not in goats following alkali treatment of the straw. Organic Matter Digestibility (OMD) of the diets was also increased (P<O.O5) after treatment. The energy digestibility of the TS-based diet was significantly increased (P<0.05) in both species. The digestibility of Crude Fibre (CF) was markedly improved (P<0.01) following treatment in both sheep and goats, but the improvement was significantly higher (P<0.05) for sheep fed on US than for the goats fed US. The belief that goats digest CF more efficiently than sheep was not proved The interspecies difference in fibre digestibility may have been due in part to the relative immaturity of the goats compared with the sheep (5 months and 15 months respectively) and also to the relatively short adaption period allowed before the trial commenced.

Highly significant increases (P < 0.001) in water intake occurred with both sheep and goats fed TS.

Values for the OMD and Metabolizable Energy (ME) of the US and TS were derived and both parameters were significantly increased (P<0.05) following treatment of the straw with alkali. TS, if adequately supplemented with nitrogen, minerals and vitamins would appear to be capable of supplying the ME requirements for maintenance and limited production in sheep and goats.