Calcium hydroxide (Ca(OH)2) is widely available in Third World countries because of extensive limestone deposits. Previous studies (reviewed by Owen et al 1984) have shown Ca(OH)2-treated straw to be prone to mouldiness and low intakes. Urea was added to Ca(OH)2 in the present study to inhibit mould and supply nitrogen. Two experiments are reported which investigated the amounts of Ca(OH)2 and urea required for improving intake and digestibility of barley straw in sheep.

Forty Suffolk x Mule store lambs (20 castrates, 20 ewe lambs) aged 8 months were used to measure intake and digestibility of 5 straws (Table 1) in a randomized block experiment, with blocking according to weight and sex. Animals were fed restricted concentrates (Table 1) and ad libitum straw (allowing refusals of 25% of intake) over a period of 35 days, with collection of faeces over the last 8 days. For treatment, straw was chopped, mixed with chemical solutions (Table 1) in a concrete mixer, and “ensiled” for 60 days (September & October) at 500 g dry matter (DM) per kg, in plastic bags contained in 45-gallon oil drums. Straw was aerated for 3 days before feeding. Untreated straw was simply chopped before feeding.