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Dhanoa MS France J Crompton LA Mauricio RM Kebreab E Mills JA Sanderson R Dijkstra J López S 《Journal of animal science》2004,82(3):733-746
A method is proposed to determine the extent of degradation in the rumen involving a two-stage mathematical modeling process. In the first stage, a statistical model shifts (or maps) the gas accumulation profile obtained using a fecal inoculum to a ruminal gas profile. Then, a kinetic model determines the extent of degradation in the rumen from the shifted profile. The kinetic model is presented as a generalized mathematical function, allowing any one of a number of alternative equation forms to be selected. This method might allow the gas production technique to become an approach for determining extent of degradation in the rumen, decreasing the need for surgically modified animals while still maintaining the link with the animal. Further research is needed before the proposed methodology can be used as a standard method across a range of feeds. 相似文献
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Rowlands M Blackwood L Mas A Cripps P Crompton C Burrow R 《The Journal of small animal practice》2011,52(10):510-514
Objective : To identify the optimal method of submission of canine and feline urine for bacterial culture. Methods : Cystocentesis samples from 250 animals (200 dogs, 50 cats) suspected of having urinary tract infections were collected. The reference aliquot, without preservative, was processed on site within 2 hours. Two further aliquots (one without preservative, one with boric acid) were stored at room temperature for up to 7 hours and then posted by guaranteed next day delivery to a commercial laboratory for analysis. Results : Forty‐seven of the samples were positive on culture in the reference test. There was no significant difference between reference test results and those of samples posted without preservative (P=0·39), but samples posted in boric acid were significantly less likely to give a positive result (P=0·01). Samples posted without preservative had a sensitivity of 82% and a specificity of 98%; for boric acid, sensitivity was 73% and specificity 99%. Clinical Significance : Postal urine samples should be submitted to the laboratory in a plain sterile tube. 相似文献
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Vitti DM Kebreab E Lopes JB Abdalla AL De Carvalho FF De Resende KT Crompton LA France J 《Journal of animal science》2000,78(10):2706-2712
The effect of increasing phosphorus (P) intake on P utilization was investigated in balance experiments using 12 Saanen goats, 4 to 5 mo of age and weighing 20 to 30 kg. The goats were given similar diets with various concentrations of P, and 32P was injected to trace the movement of P in the body. A P metabolism model with four pools was developed to compute P exchanges in the system. The results showed that P absorption, bone resorption, and excretion of urinary P and endogenous and fecal P all play a part in the homeostatic control of P. Endogenous fecal output was positively correlated to P intake (P < .01). Bone resorption of P was not influenced by intake of P, and P recycling from tissues to the blood pool was lesser for low P intake. Endogenous P loss occurred even in animals fed an inadequate P diet, resulting in a negative P balance. The extrapolated minimum endogenous loss in feces was .067 g of P/d. The minimum P intake for maintenance in Saanen goats was calculated to be .61 g of P/d or .055 g of P/(kg(.75) x d) at 25 kg BW. Model outputs indicate greater P flow from the blood pool to the gut and vice versa as P intake increased. Intake of P did not significantly affect P flow from bone and soft tissue to blood. The kinetic model and regressions could be used to estimate P requirement and the fate of P in goats and could also be extrapolated to both sheep and cattle. 相似文献
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P. L. Clarke D. W. T. Crompton Susan Arnold D. E. Walters 《British poultry science》1980,21(5):377-384
1. Some effects of removing increasing proportions of the left caecum on the remaining caecal tissue and on the right caecum were studied in young chicks during a period of 35 d. The chicks were 22 d old when the operations were carried out.
2. No differences were detected between the gains in weight of the control and experimental groups of birds.
3. A marked negative linear relationship was observed between the dry weight of the amount of caecal tissue removed when the birds were 22 d old and the weight of the left caecum at the end of the experiment.
4. The average growth rate of the left caecum (g dry tissue/week) was found to be dependent on the estimated weight of caecal tissue remaining after surgery.
5. No evidence was obtained to indicate that the growth of the right caecum responded to the removal of the left caecal tissue.
6. The morphology and histology of the operated caeca were found to be similar to the equivalent regions of the unoperated caeca. Surgical interference was not followed by any major changes in mucosal architecture.
7. In birds which had experienced unilateral caecectomy, the discharge of caecal faeces usually stopped for about 2 d. When caecal defaecation was resumed, the pattern of defaecation appeared to be the same as that observed in sham‐operated birds with both caeca intact. 相似文献
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This is a case study of the former use and management of Lakenheath Warren, a grass-heathland of 930 ha in Suffolk, England. It is suggested that the incidence of sheep and rabbit grazing, phases of cultivation, and the use of the site for military training, may have had a significant effect on the origins and development of the present-day and animal communities, which have been the subject of detailed ecological investigations. 相似文献
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Mills JA Kebreab E Yates CM Crompton LA Cammell SB Dhanoa MS Agnew RE France J 《Journal of animal science》2003,81(12):3141-3150
Previous attempts to apply statistical models, which correlate nutrient intake with methane production, have been of limited value where predictions are obtained for nutrient intakes and diet types outside those used in model construction. Dynamic mechanistic models have proved more suitable for extrapolation, but they remain computationally expensive and are not applied easily in practical situations. The first objective of this research focused on employing conventional techniques to generate statistical models of methane production appropriate to United Kingdom dairy systems. The second objective was to evaluate these models and a model published previously using both United Kingdom and North American data sets. Thirdly, nonlinear models were considered as alternatives to the conventional linear regressions. The United Kingdom calorimetry data used to construct the linear models also were used to develop the three nonlinear alternatives that were all of modified Mitscherlich (monomolecular) form. Of the linear models tested, an equation from the literature proved most reliable across the full range of evaluation data (root mean square prediction error = 21.3%). However, the Mitscherlich models demonstrated the greatest degree of adaptability across diet types and intake level. The most successful model for simulating the independent data was a modified Mitscherlich equation with the steepness parameter set to represent dietary starch-to-ADF ratio (root mean square prediction error = 20.6%). However, when such data were unavailable, simpler Mitscherlich forms relating dry matter or metabolizable energy intake to methane production remained better alternatives relative to their linear counterparts. 相似文献
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Comparative selective retention of particle size classes in the gastrointestinal tract of ponies and goats 
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下载免费PDF全文 J. Hummel F. Scheurich S. Ortmann L. A. Crompton M. Gerken M. Clauss 《Journal of animal physiology and animal nutrition》2018,102(2):429-439
There is a discrepancy in the literature on potential digesta separation mechanisms in horses, with both a selective retention of fine and of large particles postulated in different publications. To assess the net effect of such mechanisms, we fed ponies on a hay‐only diet a pulse dose of whole (unchopped) marked hay together with a solute marker, collected faeces on a regular basis, measured marker concentrations in whole faeces and in their large (2.0–16 mm), medium (0.5–1.0 mm) and small (0.063–0.25 mm) particle fraction, and calculated the corresponding mean retention times (MRTs). For comparison, the same experiment was performed in goats. In goats, as expected, MRTsolute (35 hr) was significantly shorter than MRTparticle (51 hr); only a very small fraction of particle marker was excreted as large particles (2%); and the MRT of these large particles was significantly shorter than that of small particles (with a relevant difference of 8.6 hr), indicating that those few large particles that escape the rumen do so mostly soon after ingestion. In ponies, MRTsolute (24 hr) did not differ from MRTparticle (24 hr); a higher fraction of particle marker was excreted as large particles (5%); and the MRT of these large particles was longer than that of small particles (but with a non‐relevant difference of less than 1 hr). These results indicate that no relevant net separation of digesta phases occurs in horses and that selective particle retention mechanisms in the large intestine are unlikely to represent important characteristics of the horse's digestive physiology. 相似文献