Technical annual report 2000-01
Dept. of Regional Development, Primary Industry, Fisheries and Resources technical annual report; Department of Regional Development, Primary Industry, Fisheries and Resources technical and annual report; Reports; PublicationNT; Technical bulletin (Northern Territory. Dept. of Primary Industry and Fisheries) ; no. 295
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Agriculture -- Northern Territory -- Periodicals; Fisheries -- Northern Territory -- Periodicals
Dept. of Primary Industry and Fisheries
Technical bulletin (Northern Territory. Dept. of Primary Industry and Fisheries) ; no. 295
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Technical Annual Report 2000/01 257 Crude Protein 0 2 4 6 8 10 0 1 2 3 4 5 6 7 8 9 Day D ie ta ry C P % Mitchell Flinders Red country Digestibilty 40 45 50 55 60 65 0 1 2 3 4 5 6 7 8 9Day D ig e s ti b il it y Mitchell Flinders Red country Non-Grass 0 10 20 30 40 50 60 70 0 1 2 3 4 5 6 7 8 9 Day N o n -g ra s s i n d ie t % Mitchell Flinders Red country PROJECT: Calibration of Faecal NIRS (Near Infra-red Reflectance Spectroscopy) for Predicting Diet Quality in Grazing Cattle Project Officers: J. Akeroyd and C. Materne Location: Brunchilly Station Objective: To contribute data collected from Barkly stations towards establishing faecal NIRS calibration equations for northern Australia. To gain a better understanding of cattle diets in the Barkly Tablelands region. Background: This project is part of a national project coordinated by CSIRO Townsville for the calibration of faecal NIRS across northern Australia. Calibration of faecal NIRS for northern Australia will allow pastoralists to utilise faecal NIRS technology as a support tool to assist with timely decision-making regarding supplementation and to gain a proper understanding of herd performance and pasture quality. Until now faecal NIRS technology had only been calibrated from data from eastern Queensland. To be commercially useful, its calibration is required across the whole of northern Australia. Developments: Five pen experiments were conducted on Brunchilly station at approximately two-monthly intervals. Steers in three pens were each fed one of three forage types (Mitchell grass dominated, Flinders grass dominated and mixed pasture species of red country short arid grasses). Samples of the feed offered, feed refused and faeces produced were taken daily. CSIRO subjected the faecal samples to NIRS and wet chemistry analysis and compared the results. The first trial was a test of the project methodology. Trials two and three were disrupted by unusually heavy rainfall; however, experiments four and five yielded good data. It is clear from the results that a large proportion of the diet of free-grazing cattle consisted of non-grass species, especially in good seasons. Figure 1. Faecal NIRS analysis results from experiment four, April 2001 The background (free grazing) diet is reflected in the results on day one as they enter the pens. At the end of the week the faecal measurements represent the diet fed in the pens. In early April the diet of cattle free grazing Mitchell grass country contained 9% crude protein while in the pen it was less than 6%. Similarly, the digestibility declined from almost 60% to just over 50%. This matches the decline in the non-grass (forbs and herbs) from 55% of the free grazing diet to 25% of the pen fed diet when the animals are not able to graze selectively. The trial will continue over the 2001/02 Wet season and will be reassessed at the beginning of the dry season (April 2002).