3 results
Recovery of intravenously infused chromium EDTA and lithium sulphate in the urine of cattle and their use as markers to measure urine volume
- M. K. Bowen, D. P. Poppi, S. R. McLennan
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A series of metabolism experiments investigated the recovery of continuous-, intravenously infused chromium complexed with ethylenediamine tetra-acetic acid (CrEDTA) and lithium sulphate in the urine of cattle with a view to using the markers to estimate urine and metabolite output in grazing cattle. The recovery of Cr in urine from these infusions was similar (90%) in metabolism trials when cattle consumed three very contrasting diets: high-grain formulated pellet, lucerne hay (Medicago sativa) or low-quality native grass hay (predominantly Heteropogon contortus). By contrast, Li recovery in urine averaged 46.3 ± 0.40% and 72.6 ± 0.43% for native pasture and lucerne hays, respectively, but was not constant across days. There was negligible transfer of Cr from CrEDTA in blood serum to the rumen or faeces, whereas appreciable quantities of infused Li were found in both. The ratio of urine volume estimated by spot samples and marker dilution of Cr, to urine volume measured gravimetrically, was 1.05. In grazing studies using rumen-fistulated (RF) steers grazing seven different tropical and temperate grass and legume pastures, the ratio of concentrations of purine derivatives (PD) to Cr in spot samples of urine was shown to vary diurnally in the range of 49% to 157% of the average 24 h value. This finding indicated the need for regular sampling of urine to achieve an accurate average value for the PD : Cr ratio in urine for use in estimating urinary PD excretion and hence microbial protein production in the rumen. It was concluded that continuous, intravenous infusion of CrEDTA resulted in a constant recovery of Cr in the urine of cattle across diets and, provided an intensive sampling regime was followed to account for diurnal variation, it would be suitable as a marker to estimate urine volume and urinary output of PD in grazing cattle.
22 - Implications of observed primary lithologies
- from Part V - Synthesis
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- By G. J. Taylor, Hawaii Institute of Geophysics & Planetology, 1680 East-West Road, Post 504 Honolulu, HI 96822, USA, S. M. McLennan, Department of Geosciences, SUNY Stony Brook Stony Brook, NY 11794-2100, USA, H. Y. McSween, Jr., Department of Earth & Planetary, Science University of Tennessee, Knoxville, TN 37996-1410, USA, M. B. Wyatt, Brown University, Department of Geological, Science 324 Brook Street Providence, RI 02912-1846, USA, R. C. F. Lentz, University of Hawai'i at Manoa Hawai'i, Institute of Geophysics and Planetology 1680 East-West Road, POST 602 Honolulu, HI 96822, USA
- Edited by Jim Bell, Cornell University, New York
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- Book:
- The Martian Surface
- Published online:
- 10 December 2009
- Print publication:
- 05 June 2008, pp 501-518
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Summary
ABSTRACT
Data from Martian meteorites, orbital remote-sensing instruments, and in situ measurements at robotic landing sites reveal that Mars has a heterogeneous surface composition. We use these data to infer the compositional and mineralogical nature of Martian igneous rocks. Basaltic rocks dominate, but highly mafic magmas also formed, producing cumulate rocks inside lava flows. Cumulate rocks also formed in intrusions. Evolved, silicic rocks occur, but are not abundant. The diversity of igneous rocks indicates several distinctive source regions in the Martian mantle. These sources probably formed early in Martian history as the result of crystallization in a magma ocean followed by overturn of an unstable cumulate pile. Shergottites alone represent at least two distinct mantle sources (assuming no crustal assimilation), with mixing between them, but could represent several distinct sources on the basis of initial Sr-isotopic compositions. The nakhlites may represent a somewhat complementary source, but there is clearly an additional source with subchondritic Ba/La. Surface Types 1 and 2 are probably composed of multiple types of igneous rock, possibly mixed with altered materials, and on average are different in trace element (K, Th) and Fe abundances. They may be derived from distinct mantle source regions. The crust appears to have been constructed by basaltic magmatism, some associated with primary differentiation (probably a magma ocean), the rest formed by partial melting during mantle overturn and other dynamic processes.
Improved beef production from supplementation of Hereford, Brahman and crossbred cattle grazing low and medium quality pastures in the subtropics of Australia
- D. W. Hennessy, P. J. Williamson, D. J. McLennan, R. J. Farquharson, S. G. Morris, R. E. Darnell
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- Journal:
- Animal Science / Volume 66 / Issue 1 / February 1998
- Published online by Cambridge University Press:
- 02 September 2010, pp. 93-104
- Print publication:
- February 1998
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Subtropical grasslands are low in organic matter digestibility (OMD) (0·60) and nitrogen (N) (15 g/kg) for much of the year and this limits cattle production which is characterized by low calving rates and low weaning weights. Production has been based on Bos taurus British breeds of cattle but this is changing and now many breeding herds comprise B. indicus cows and their crosses. This change has increased some aspects of production, but low calving rates persist.
A 4-year study was undertaken with a view to improve calving rates and weaner output by supplementing cows grazing either native or improved pastures with a high protein oilseed meal (cottonseed meal; CSM) on four sites. These sites were subdivided into a total of 36 paddocks to allow for two replications in a 3 breeds × 3 supplementation rates × 2 pastures factorial design. Selected cows (no. = 216) from Hereford (H), Brahman (B) and Brahman × Hereford (BH) breed types were set to graze either native pastures (0·45 to 0·62 OMD, 8 to 15 gN per kg; low quality) or improved pastures (0·47 to 0·67 OMD, 10 to 22 g N per kg; medium quality). Cows were given either 0, 750 or 1500 glday of CSM for 130 days from calving until 4 weeks into a 12- to 13-week mating period. The CSM was given as two meals per week.
Live weight at mating of cows on the low quality pasture was increased (P < 0·01) over those not supplemented by feeding either 750 g CSM per day (H and B cows) or 1500 g CSM per day (all cows). There was no significant effect of supplementation on the mating weights ofB cows grazing the medium quality sites. Calving rate ofB cows was not increased by their supplementation on either low (4-year mean 58·3 %) or medium quality pastures (66·8%) but did tend to be higher in H cows when supplemented at 1500 g CSM per day on the low (66·7 v. 78·0 (s.e. 6·09) %; P < 0·1) and medium quality pastures (70·5 v. 93·5 (s.e. 4·72) %). An increased calving rate (65·8 (s.e. 6·6) % to 83·2 (s.e. 5·82) % in supplemented BH cows grazing low quality pastures approached significance (P < 0·1) when given CSM at 1500 glday but there was no increased trend in calving rate when this breed type was supplemented on medium quality pastures.
Weaning weights of calves from and B and BH cows were increased (P < 0·05) by supplementation of their dams at 750 glday and for calves weaned from H cows supplemented at 1500 glday of CSM. Supplementation at 1500 glday on low quality pastures increased weaner output per cow mated by 120% for H, by 65% for BH cows and by 50% for B cows. Weaner output was increased by 34 and 40%, respectively, for B and H cows when supplemented at 750 glday and grazing medium quality pastures but there was no significant effect of supplementation on output from BH cows. Responses in many parameters differed between years. These results were interpreted as a response to the protein in the oilseed meal supplement by B. taurus and B. taurus × B. indicus cross cows grazing on the subtropical pastures. The study also highlighted that responses to the meal differed between breed types, between the quality of the grazed pasture and between the years of supplementation.