2 results
Faecal near-IR spectroscopy to determine the nutritional value of diets consumed by beef cattle in east Mediterranean rangelands
- S. Y. Landau, L. Dvash, M. Roudman, H. Muklada, D. Barkai, Y. Yehuda, E. D. Ungar
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Rapid assessment of the nutritional quality of diets ingested by grazing animals is pivotal for successful cow–calf management in east Mediterranean rangelands, which receive unpredictable rainfall and are subject to hot-spells. Clipped vegetation samples are seldom representative of diets consumed, as cows locate and graze selectively. In contrast, faeces are easily sampled and their near-IR spectra contain information about nutrients and their utilization. However, a pre-requisite for successful faecal near-infrared reflectance spectroscopy (FNIRS) is that the calibration database encompass the spectral variability of samples to be analyzed. Using confined beef cows in Northern and Southern Israel, we calibrated prediction equations based on individual pairs of known dietary attributes and the NIR spectra of associated faeces (n=125). Diets were composed of fresh-cut green fodder of monocots (wheat and barley), dicots (safflower and garden pea) and natural pasture collected at various phenological states over 2 consecutive years, and, optionally, supplements of barley grain and dried poultry litter. A total of 48 additional pairs of faeces and diets sourced from cows fed six complete mixed rations covering a wide range of energy and CP concentrations. Precision (linearity of calibration, R2cal, and of cross-validation, R2cv) and accuracy (standard error of cross-validation, SEcv) were criteria for calibration quality. The calibrations for dietary ash, CP, NDF and in vitro dry matter digestibility yielded R2cal values >0.87, R2cv of 0.81 to 0.89 and SEcv values of 16, 13, 39 and 31 g/kg dry matter, respectively. Equations for nutrient intake were of low quality, with the exception of CP. Evaluation of FNIRS predictions was carried out with grazing animals supplemented or not with poultry litter, and implementation of the method in one herd over 2 years is presented. The potential usefulness of equations was also established by calculating the Mahalanobis (H) distance to the spectral centroid of a calibration population of 796 faecal samples collected throughout 2 years in four herds. Seasonal trends in pasture quality and responses to management practices were identified adequately and H<3.0 for 98% of faecal samples collected. We conclude that the development of FNIRS equations with confined animals is not only unexpensive and ethically acceptable, but their predictions are also sufficiently accurate to monitor dietary composition (but not intake) of beef cattle in east Mediterranean rangelands.
Intake, growth and carcass characteristics of young ostriches given concentrates with and without pasture
- R. Nitzan, D. Barkai, Z. Nitsan, S. Landau1
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- Journal:
- Animal Science / Volume 74 / Issue 1 / February 2002
- Published online by Cambridge University Press:
- 18 August 2016, pp. 71-79
- Print publication:
- February 2002
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Although ostriches are herbivores, their diets in commercial farming in Israel consist mainly of concentrates. The objective of this study was to evaluate an alternative for fattening ostriches aged 10 to 30 weeks, which combines pasture with concentrate feeding. Chicks were allotted to three treatments. Diet of group C40 consisted of concentrate only, provided at 40 g/kg body mass (mb). Groups CG20 and CG30 received concentrate at 20 and 30 g/ kg mb, respectively, and grazed 4 to 6 h/day on lush green alfalfa (Medicago sativa), sown barley (Hordeum vulgare), natural pasture or sulla (Hedysarum coronarium). During the last 10 weeks of experiment, groups CG20 and CG30 were merged into one group, managed as CG20 and grazed natural pasture, sulla, alfalfa, or vetch (Vicia sativa). Ostriches from group CG20 and CG30 consumed 390 (s.e.30) g and 260 (s.e. 20) g DM per day at pasture, i.e. 0·46 and 0·28 of their total daily intake, respectively. Pasture intake for CG20 was higher (P < 0·05) than for CG30. Intake of pasture (both grazing treatments combined) was twice as much as on natural pasture or alfalfa as on barley. These results were consistent with the ostriches’ preference for forbs rather than grasses in the natural pasture. The mean organic matter digestibility was 0·84 (s.e. 0·01), ostriches gained at 347 (s.e. 13) g/day, and the food conversion ratio was 3·05 (s.e. 0·16), with no effect of group. Also, grazing did not affect the dressing rate (0·47, s.e. 0·015) or the size and mass of the different parts of the gastro-intestinal tract, with the exception of the glandular and muscular stomachs, which were proportionately 0·4 (P < 0·05) heavier in grazing birds. Lower (P < 0·05) fat content (33·8 v. 26·5 g/kg) but not tenderness, of a selected muscle (fibularis longus) was found for grazing birds. This study suggests that, in young ostriches, grazing lush green pasture may reduce concentrate intake by proportionately 0·4, without altering growth performance or carcass yield and quality.