The intake and performance of cattle grazing irrigated pastures. 2. Effect of pasture length on growth of steers

Abstract

The organic matter intakes (OMI) and liveweight of twenty-four weaner steers grazing either short or long irrigated annual pastures were compared during May to November in 1964 and 1965 at Leeton, New South Wales. The OMI were estimated from determinations of faeces organic matter output using chromic oxide dilution, and of digestibility estimated from a faeces nitrogen-digestibility relationship for pen-fed cattle. Weaners that grazed the short or long pasture did not differ significantly in final liveweights (356 v.361 kg respectively, 1964; 357 v.361 kg, 1965) or OMI (4.99 v.5.42 kg day-1, 1964; 5.78 v.6.06 kg day-1, 1965) although available dry matter was less (P < 0.05) in short than in long pastures in both years. The OMI were commensurate with the 0.6 kg mean daily liveweight gains of weaners, which however were smaller than other reported growth rates, and an unsatisfactory production from the costly pastures. The reasons for the small liveweight gains are unknown but it is suggested that high moisture contents (85 per cent) of pastures restricted intake, or that high clover contents (58 per cent) caused bloating and rumen distension which thereby restricted intake.