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Littérature scientifique sur le sujet « Defaunated sheep »
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Articles de revues sur le sujet "Defaunated sheep"
1
Hegarty, R. S., C. Shands, C. Harris et J. V. Nolan. « Productivity and pasture intake of defaunated crossbred sheep flocks ». Australian Journal of Experimental Agriculture 40, no 5 (2000) : 655. http://dx.doi.org/10.1071/ea99091.
Texte intégralRésumé :
From a flock of pregnant crossbred ewes, 63 were established as protozoa-free by treatment with alkanate 3SL3 and 64 ewes were maintained as controls. The controls included 20 ewes, which had been defaunated and subsequently re-inoculated with protozoa. After lambing, both flocks were grazed in a 6-paddock rotation until weaning at 20 weeks of age. Defaunated ewes were heavier than control ewes throughout lactation and had a higher urinary allantoin concentration than the control ewes. Intake and apparent digestibility of pasture dry matter by ewes did not differ between groups although these estimates were confounded by differences in pasture composition between the paddocks used. Both groups selected a diet with digestibility approximately 10% units higher than the bulk digestibility of pasture on offer. Control ewes selected a higher proportion of white clover in their diet than was available in the pasture (24% v. 2%) but defaunated ewes did not exhibit preferential selection for clover. Lambs from defaunated ewes were heavier at birth, remained heavier until weaning and grew more wool than lambs from control ewes. Contamination of fauna-free ewes and lambs with protozoa was first observed at weaning and protozoa were detected in 41 out of 60 lambs, 4 weeks after contamination was first detected. Study of defaunated ewes returned to a flock of untreated ewes confirmed rapid spread of contamination into defaunated ewes with small entodiniomorph protozoa establishing first.
2
Fenn, PD, et RA Leng. « The effect of bentonite supplementation on ruminal protozoa density and wool growth in sheep either fed roughage based diets or grazing ». Australian Journal of Agricultural Research 41, no 1 (1990) : 167. http://dx.doi.org/10.1071/ar9900167.
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In penned sheep offered a mainly roughage diet, supplementation with 30, 50 or 60 g/day bentonite consistently increased the density of ruminal protozoa. The effect of 15 g/day bentonite administered via the drinking water to pregnant grazing ewes that were either normally faunated or had been defaunated for 6 months was studied. The wool growth of defaunated sheep at pasture was 25% greater (P < 0.05) than that of faunated animals. The wool growth of the latter was increased 17% (P < 0.15) by the addition of 15 g/day bentonite to their drinking water, while a similar addition of bentonite to defaunated sheep had no effect on wool growth. In this field study, supplementation with bentonite increased the population densities of protozoa free in the ruminal fluid of faunated sheep by 51% (5.6 X 105 v. 3.7 X 105, P<0.07). It is suggested that this allows a greater flow of protozoal protein from the rumen to the intestines, leading to increased wool growth in response to supplements of bentonite.
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Cottle, DJ. « Effects of defaunation of the rumen and supplementation with amino acids on the wool production of housed Saxon Merinos. 2. Methionine and protected methionine ». Australian Journal of Experimental Agriculture 28, no 2 (1988) : 179. http://dx.doi.org/10.1071/ea9880179.
Texte intégralRésumé :
In experiment 1, 6 groups, each of 10 superfine Merino wethers, were individually penned indoors and hand-fed oats, wheat straw and whole lupins, either alone or with 2 g/day of DL-methionine or 6.6 g/day of fatty acid coated methionine (Ketionin) for 23 weeks. Following shearing the 6 groups were hand-fed lucerne-chopped hay in experiment 2 either alone or with hydroxymethyl-methionine (Mepron) or Ketionin for 23 weeks. In both experiments the rations were fed at maintenance level and were offered 3 times a week. Half of the sheep had no rumen ciliate protozoa following treatment in a previous trial. In experiment 1, defaunated sheep produced an additional 6.5%clean wool on the supplemented oats plus lupins rations. Inclusion of Ketionin in the ration of defaunated sheep resulted in an 11% increase in clean wool growth, without affecting wool quality. In experiment 2 defaunated sheep produced an additional 6% clean wool on the lucerne-chopped hay ration. No responses to defaunation occurred on the supplemented rations. Inclusion of both forms of protected methionine in the ration (providing 2 g methionine/sheep.day) resulted in 23% and 13% higher clean wool production in the faunated and defaunated sheep respectively. Fibre diameter of wool was increased by 0.7 pm in sheep receiving Mepron and 0-5 pm in sheep receiving Ketionin. The wool grown by suppiemented sheep remained suitable for the 'Sharlea' trade (< 17.5 �m). It is concluded that wool growth responds more to defaunation on high energy-low protein diets. Wool growth responses to supplementation with protected methionine were greater on 100% roughage diets than on high grain diets. Further study is needed before an optimal ration for superfine wool production is formulated.
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Ushida, K., J. P. Jouany et P. Thivend. « Role of rumen protozoa in nitrogen digestion in sheep given two isonitrogenous diets ». British Journal of Nutrition 56, no 2 (septembre 1986) : 407–19. http://dx.doi.org/10.1079/bjn19860121.
Texte intégralRésumé :
1. The effect of protozoa on digestion in the rumen was studied using either defaunated or faunated sheep.2. Six wethers, each fitted with rumen and simple duodenal cannulas, were given two isonitrogenous diets containing either lucerne (Medicago sativa) hay (diet L) or sodium hydroxide-treated wheat straw (diet S). The diets were given in eight equal portions per day at 3-h intervals. The mean intake of dry matter, 53 g/kg body-weight0.75per d, was similar for the two diets and each diet had a similar digestible organic matter content. Diet L promoted a large protozoal population and was rich in nitrogen sources of low rumen-degradability, while diet S supported a smaller protozoal population and was rich in rumen-degradable N.3. Digesta flow at the duodenum was estimated by means of a dual-marker technique using chromium-mordanted lucerne hay and polyethylene glycol as markers. The microbial flow at the duodenum was estimated using diaminopimelic acid (DAPA), nucleic-acid purine bases (PB) and35S incorporation simultaneously. The different microbial markers were compared in the defaunated sheep. Protozoal N contribution was estimated in faunated sheep.4. Defaunated sheep had lower rumen ammonia concentrations and molar proportions of butyric acid than faunated sheep, but they had higher molar proportions of propionic acid.5. Rumen organic matter digestion was reduced by defaunation, but this decrease was compensated for by increased intestinal digestion.6. There was a net increase of N flow (approximately 10 g/d) between mouth and duodenum in defaunated sheep. This was explained by increases in both microbial and dietary N flows from the rumen compared with faunated sheep.7. The influence of protozoa on solid- and liquid-phase retention times in the rumen is discussed, as well as the protozoal contribution to microbial N flow in the duodenum of faunated sheep.
5
Rowe, J. B., A. Davies et A. W. J. Broome. « Quantitative effects of defaunation on rumen fermentation and digestion in sheep ». British Journal of Nutrition 54, no 1 (juillet 1985) : 105–19. http://dx.doi.org/10.1079/bjn19850097.
Texte intégralRésumé :
1. Studies on the quantitative significance of protozoa on carbon and nitrogen digestion and metabolism in the rumen were carried out in sheep given a diet of pelleted concentrate (500 g/d) and chopped hay (500 g/d).2. Measurements were made of apparent digestibility; flows of organic matter and dietary and microbial non-ammonia N (NAN) (using 15NH+4) to the duodenum; and rates of production, interconversion and metabolism of the major C fermentation end-products (from mathematical modelling of 14C isotope values).3. The population density of bacteria in the rumen increased as a result of defamation (28.6 compared with 8.2 x 10° organisms/ml). This high density was associated with greater utilization of volatile fatty acids (VFA) within the rumen.4. The rate of irreversible loss (IL) of bicarbonatefcarbon dioxide from the rumen was greater in the defaunated animals (98.5 v. 57.2 g C/d) but the IL from the blood was greater in the faunated group (138.6 v. 106.1 g C/d). This is consistent with the hypothesis that the high population density of bacteria found in the rumen fluid of defaunated animals may result in increased fermentation of rumen VFA and digestible dietary carbohydrate, thereby increasing the output of CO2 from the rumen and reducing the quantity of VFA (hence energy) available to the host.5. There was no difference in the flow of organic matter (OM) to the duodenum but there was a higher faecal excretion of OM in defaunated animals (apparent OM digestibility: 0.72 in faunated, 0.67 in defaunated).6. Defamation did not significantly increase the flow of NAN to the duodenum, the percentage of duodenal NAN of bacterial origin or the quantity of microbial NAN synthesized/g organic matter fermented. Faecal excretion of NAN was higher in defaunated animals (5.3 v. 3.6 g N/d).
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Enev, E., A. Petkov, N. Oblakov et N. Todorov. « Some Aspects of Carohydrate Metabolism in Defaunated Sheep ». Asian-Australasian Journal of Animal Sciences 2, no 3 (1 septembre 1989) : 471–72. http://dx.doi.org/10.5713/ajas.1989.471.
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Ushida, K., C. Kayouli, S. De Smet et J. P. Jouany. « Effect of defaunation on protein and fibre digestion in sheep fed on ammonia-treated straw-based diets with or without maize ». British Journal of Nutrition 64, no 3 (novembre 1990) : 765–75. http://dx.doi.org/10.1079/bjn19900078.
Texte intégralRésumé :
Using a defaunating method which preserved bacteria and fungi in the rumen, the effect of protozoa on protein and fibre digestion was studied in six adult wethers in relation to the nature of the diet. Sheep were given daily, 42 g dry matter (DM)/kg metabolic body-weight (W0.75), one of two isonitrogenous diets: one contained ammonia-treated wheat straw as the only energy source (diet S) and the other was supplemented with maize grain pellets (diet SM). Mean daily intakes (g/d) of nitrogen, neutral-detergent fibre and acid-detergent fibre were respectively 22, 573 and 373 for diet S and 23, 450 and 334 for diet SM. Elimination of protozoa increased duodenal non-ammonia-nitrogen flow. This result was mainly due to an increase in microbial protein flow and, to a lesser extent, to a higher dietary protein flow. Defaunation markedly increased the efficiency of microbial protein synthesis. Maize-grain supplementation had a net positive effect on this variable in defaunated sheep, but not in faunated sheep. Cell-wall carbohydrates were less well digested in the defaunated rumen, and the negative effect of defaunation was greatest with the diet SM. Intestinal fibre digestion increased in the defaunated sheep especially in those fed on diet SM, but not enough to compensate for the decrease in rumen digestion.
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Santra, A., S. Parthasarathy et S. A. Karim. « Effect of defaunation on body conformation changes, wool yield and fibre characteristics of growing lambs in a hot semiarid environment ». Australian Journal of Experimental Agriculture 47, no 7 (2007) : 789. http://dx.doi.org/10.1071/ea05106.
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The efficacy of sodium laurel sulfate as a defaunating agent, as well as effect of defaunation on body confirmation changes, wool yield and fibre characteristics, were evaluated in growing lambs in a 90-day feeding experiment. Forty-five Malpura male weaner (90-day old) lambs were divided into three equal groups: defaunated, refaunated and faunated. The lambs of defaunated and refaunated groups were defaunated by oral administration of sodium laurel sulfate at the rate of 8 g/100 kg liveweight as a 10% aqueous solution. Six days after defaunation, all the lambs of the refaunated group were refaunated by inoculation of 100 mL rumen content per lamb drawn from a normal faunated sheep. All the experimental lambs were maintained under stall feeding on a complete feed containing 50 : 50 Pala (Ziziphus nummularia) leaf and concentrate. Treatments did not differ in intake of dry matter, digestible crude protein or digestible energy. Body height and paunch girth were greater (P < 0.01) in defaunated compared to refaunated and faunated lambs. With similar dry matter intake in the three experimental groups, liveweight gain, feed conversion efficiency and wool yield were higher (P < 0.01) in defaunated lambs. The wool fibre diameter and medullation percentage were higher (P < 0.01) in defaunated than refaunated and faunated lambs. It was concluded from the study that, with similar dry matter intake and plane of nutrition, the growth rate, feed conversion efficiency and wool yield were higher in defaunated lambs, as compared to refaunated and faunated lambs. Higher paunch girth in defaunated lambs resulted in a pot-bellied appearance of the animals.
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Frumholtz, P. P., R. J. Wallace, C. J. Newbold et E. R. Ørskov. « Long-term changes in rumen fermentation in defaunated sheep ». Proceedings of the British Society of Animal Production (1972) 1991 (mars 1991) : 77. http://dx.doi.org/10.1017/s0308229600020274.
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The removal of ciliate protozoa, or defaunation, results in the establishment of a new ecosystem in the rumen, consisting only of bacteria and fungi. Although extensive research has been done on ciliate-free ruminants, the role of protozoa in the rumen still provokes considerable debate. The diversity of experimental design, such as animal species, defaunation method, and diet could account for many of the differences observed between defaunation studies. Also it is important to examine the stability of the ciliate-free ecosystem. The aim of this study was to investigate changes in rumen fermentation of ciliate-free sheep over a period of one year.Eight male castrated sheep, weighing 60-70 kg, received twice daily 700 g of a diet of hay, barley, molasses, fish meal and vitamins/minerals (500, 299.5, 100, 91 and 9.5 g/kg DM respectively). Four sheep were defaunated by the rumen washing technique (Jouany and Senaud, 1979) and kept in isolated pens while the other four were left faunated with a mixed type A ciliate protozoa population. Rumen samples were withdrawn via the rumen cannula and blood samples were taken from the jugular vein -1, 0, 1, 2, 4 and 6 h after feeding. There were three sampling periods: one month, six months and one year after defaunation.
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Van Nevel, C. J., S. De Smet et D. I. Demeyer. « Digestion in defaunated and refaunated sheep fed soybean oil hydrolysate or crushed toasted soybeans ». Netherlands Journal of Agricultural Science 41, no 3 (1 septembre 1993) : 205–19. http://dx.doi.org/10.18174/njas.v41i3.620.
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Defaunated then refaunated sheep were given diets containing soyabean oil hydrolysate (SOH: 70 g/day) or an equivalent amount of lipids administered as crushed toasted soyabeans (TSB). Defaunation increased molar percentage of propionate in the rumen, while butyrate decreased. SOH caused a similar effect in both the defaunated and refaunated rumen, while the effect on acetate proportions was variable. Protozoal counts were lower after feeding SOH. Crushed toasted soyabeans had a minor effect on rumen fermentation pattern. Rumen digestibility of organic matter was decreased by both defaunation and SOH feeding, with a concomitant shift in digestion to the lower intestinal tract. Total tract digestibility was not affected. Both treatments increased nonammonia N flows at the duodenum, but this was only significant with defaunation. Total tract digestion of N remained almost constant. Defaunation resulted in more microbial protein reaching the duodenum. Except for the TSB diet, total lipid leaving the rumen equalled intake. Total tract digestibility of total lipid was much higher with SOH and TSB than with controls. Defaunation almost doubled microbial growth efficiency and this value tended to increase by SOH feeding. The decrease of protozoal count or even elimination of protozoa after lipid feeding could not entirely explain the change in rumen metabolism, as additional changes in defaunated sheep were shown.
Thèses sur le sujet "Defaunated sheep"
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Altaye, Belete Teferedegne. « The use of foliage from multipurpose trees to manipulate rumen fermentation ». Thesis, University of Aberdeen, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.322477.
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