Turnips with chemically-treated straw for beef production. 1. The effects on the growth of steers

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Abstract
A growth trial lasting 84 days and digestibility trials were carried out with Hereford × Friesian steers weighing initially 360 kg. Daily dry-matter intakes (kg) of 32 steers offered turnips with blood meal (250 g/day) and straw treated with sodium hydroxide (SP), urea (UP), ammonia (AP) or untreated (CP), and of a further eight steers offered turnips and ammonia-treated straw without a supplement of blood meal (A) were 6·5 (SP), 6·0 (UP), 6·6 (AP), 5·9 (CP) and 6·3 (A); live-weight gains (kg/day) were 0·69, 0·58, 0·60, 0·37 and 0·39 respectively. The non-protein nitrogen intake of steers on treatments SP and CP were matched to those on treatments AP, A and UP by the addition of urea. Coefficients of apparent straw organic matter digestibility were 0·629 (SP), 0·531 (UP), 0·578 (AP), 0·446 (CP) and 0·569 (A). Overall food intakes on all treatments were low initially (88 g/kg W0·73) and declined further to 78 g/kg W0·73. Live-weight gains also were low; those of steers given diets CP and A were lower (P< 0·001) than gains of steers on other treatments.Improvements in the apparent digestibility of straw were obtained by chemical treatment but all values, except that of the UP group, were low. The supplementation of ammonia-treated straw with blood meal (AP) produced a higher (P< 0·001) growth rate in steers compared with that of steers receiving ammonia-treated straw alone (A). The low mean pH (6·48) and ammonia concentration (9 mg/100 ml) of rumen liquor sampled during the growth trial suggest that the poor growth rates and low food intake of cattle in this trial may be associated with the rapid release of soluble sugars from turnips given only once daily.