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1.
The development of gastro-intestinal helminth diversity was monitored in lambs grazing alone or grazing with heifers in the ratio one heifer to four lambs. Five successive cohorts of lambs were studied from January 1994 to May 1996. Each cohort of lambs grazed irrigated pastures of Pangola grass for 4 months (from weaning to 6 months of age). A total of 50 lambs was necropsied and their worms counted and identified at the end of each grazing period. Four heifers were also necropsied on one occasion. Special attention was dedicated to the identification of the most pathogenic worm, i.e. Haemonchus spp. Malate dehydrogenase polymorphism in H. contortus was studied in order to evaluate changes between cohorts and between grazing managements. The species diversity was estimated by Shannon diversity indices (main species or all species). It was higher in the mixed grazing group than in the lambs that grazed alone. Diversity increased in successive cohorts. This was due in part to the acquisition of Cooperia spp. of cattle origin. The increase in diversity in the mixed grazing lambs corresponded to the lower faecal egg excretion and better weight gains recorded previously in that group. There seemed to be no cross-transmission of H. similis found in heifers and H. contortus harboured by lambs. The latter species was not morphologically or genetically different in the lambs grazed alone or with heifers, indicating that the presence of cattle did not modify qualitatively the transmission of H. contortus. 相似文献
2.
The organic forms of phosphorus in the soil appear to be changing as rice growing intensifies and the soil is flooded for longer in tropical Asia. To examine these changes, we extracted the labile mobile humic acid (MHA) and more recalcitrant calcium humate (CaHA) fractions from soils supporting long‐term field trials in the Philippines and analysed them by solution 31P‐nuclear magnetic resonance (NMR) spectroscopy. Diester P and sugar‐diester P accumulated moderately with increasing intensity of irrigated rice cropping, reaching a combined 42% of all MHA‐P for a triple‐cropped irrigated field compared with 28% for fully aerated fields growing dryland crops. The mono‐ to diester P ratio decreased by 43% for the MHA and CaHA from the aerated fields to the triple‐cropped field. Smaller effects on forms of P were noted for the rates and type of N, P and K fertilizer and site effects. The effects of treatment and site were more noticeable in the MHA than in the CaHA. The proportions in the NMR spectra were tightly correlated with visible light absorption, concentrations of organic free radicals and H, and 15N‐NMR spectral proportions, which indicate the degree of humification. The MHA and CaHA accounted for only 0.6–8.3% and 0.9–5.7%, respectively, of total P; most of the P is inorganic. 相似文献
3.
Mandonnet N Bachand M Mahieu M Arquet R Baudron F Abinne-Molza L Varo H Aumont G 《Veterinary parasitology》2005,134(3-4):249-259
The control of gastrointestinal nematodes requires an understanding of their epidemiology so that particular parasite stages can be targeted. Dam infection during early lactation is one example of this in ruminant nematode infections. The existence of the peri-parturient relaxation in immunity and its impact on productivity were examined in a Creole goat flock from Guadeloupe, exposed to mixed natural infection (predominantly Haemonchus contortus and Trichostrongylus colubriformis). A total of 1,511 l were obtained from 909 does resulting from 463 dams and 150 sires. Fecal and blood samples were collected at kidding before anthelmintic drenching, 4 and 6 weeks after kidding. The traits analyzed were logarithm transformed fecal egg counts (FEC), packed cell volume (PCV), and logarithm transformed blood eosinophilia counts (EOS) for does at each sampling point and changes in these during the postpartum period. With the exception of the PCV values measured at kidding, lactating does had significantly higher FEC and lower PCV than control dry does at every sampling point. Geometric means of FEC in lactating does were 819 +/- 174, 677 +/- 146 and, 699 +/- 160 eggs per gram (EPG) at kidding, 4 and 6 weeks after kidding respectively. Geometric means of FEC in dry does were 187 +/- 57, 89 +/- 28, 133 +/- 43 at these time points, respectively. EOS differences were not consistent between groups and probably not specific enough for variations in Creole goats' peri-parturient rise to be discussed. As does aged, their egg output decreased and primiparous does always had greater egg output than multiparous ones. Overall, does' FEC at 4 weeks after kidding decreased by 1.3% each year. The higher the litter size, the higher the FEC at kidding and inverse applied for PCV measurements. Does that stopped lactating had significantly lower FEC and higher PCV values than lactating does with low milk yields. Higher infection rates during early lactation in Creole goats were recorded in does with lower maternal ability assessed by the average daily weight gain of kids between 10 and 30 days of age. Kids from dams with higher FEC (i.e. >600 EPG higher than corresponding does) had 17% lower average daily weight gain between 30 and 70 days postpartum and were approximately 1 kg lighter at weaning than kids from dams with lower FEC. Thus, it is clear that a peri-parturient rise in FEC exists in Creole goats. By controlling the intensity of this peri-parturient rise in FEC, herd health and productivity could be substantially improved. 相似文献
4.
Haemonchus infection was monitored for 2 years (six kidding periods) in a Creole goat flock grazing under oceanic-tropical climate. Two hundred and thirty individual does were involved from late pregnancy to weaning. Anaemia diagnoses using Famacha method and packed cell volume (PCV) were compared. The best agreement (Kappa=0.33) was found if anaemia was declared when PCV values fell to 16 or below and Famacha score was 4 or 5. Drenching policy according to Famacha method was compared to systematic drenching policy. Using the Famacha method allowed a dramatic decrease in anthelmintic use during the periparturient period (0.57 individual dose instead of three doses for the control). The proportion of the nematode population on the pasture not derived from previously-treated goats (in refugia) was estimated to about 79% (65-90%) of the pasture contamination derived from the Famacha group. On the average, goats which needed to be drenched produced less than the control or undrenched goats (kid average daily gain was decreased by about 15%). The repeatability of the need for drenching individual does was estimated to 0.41. The older goats or the goats in poorer body condition at kidding needed more drenching than the younger animals and the animals in good body condition. Consequently the Famacha method may be used as an additional tool for the culling management. 相似文献
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6.
S. Mahieu F. Germon H. Hauggaard-Nielsen E.S. Jensen 《Soil biology & biochemistry》2009,41(2):380-554
In the next few years, grain legumes should be used as a mean of N acquisition in cropping systems due to the depletion of non-renewable sources of energy. However, this requires improvements in the accuracy with which biological N2 fixation, N balances and the N benefit for following crops are estimated. Moreover, grain legume crops are largely influenced by water stress while the world area exposed to drought periods may increase in the coming years due to global warming. This work aims to quantify biomass and N accumulation, N partitioning between above and below ground parts and N rhizodeposition by a pea (Pisum sativum L.) when influenced by water stress. In a controlled environment, pea plants were exposed to a severe drought or not stressed, either at flowering or during pod filling. N rhizodeposition was measured using the split root method and plants were harvested at the end of flowering (59 days after sowing, DAS 59), at the end of the drought period applied during pod filling (DAS 74) and at maturity (DAS 101). Water stress strongly affected pea dry weight and N accumulation. In both stressed treatments, nodule biomass and N content were reduced by about 65% in the absence of stress. Regardless of the treatment, total below ground plant N (root N + N rhizodeposition; BGN) and N rhizodeposition were correlated with total plant N content and the proportion of BGN to total plant N was similar among treatments at each sampling date. At DAS 59 and 74, the N contained in rhizodeposits represented around 30% of the total BGN and increased to around 60% at maturity though BGN decreased from around 20 to 13% of the total plant N between DAS 74 and maturity. The results suggest that water stress has no specific effect on N partitioning between above and below ground parts. 相似文献
7.
The aim of the present study was to test and improve the reliability of the 15N cotton-wick method for measuring soil N derived from plant rhizodeposition, a critical value for assessing belowground nitrogen input in field-grown legumes. The effects of the concentration of the 15N labelling solution and the feeding frequency on assessment of nitrogen rhizodeposition were studied in two greenhouse experiments using the field pea (Pisum sativum L.). Neither the method nor the feeding frequency altered plant biomass and N partitioning, and the method appeared well adapted for assessing the belowground contribution of field-grown legumes to the soil N pool. However, nitrogen rhizodeposition assessment was strongly influenced by the feeding frequency and the concentration of labelling solution. At pod-filling and maturity, despite similar root 15N enrichment, the fraction of plants' belowground nitrogen allocated to rhizodeposition in both Frisson pea and the non-nodulating isoline P2 was 20 to more than 50% higher when plants were labelled continuously than when they were labelled using fortnightly pulses. Our results suggest that when 15N root enrichment was high, nitrogen rhizodeposition was overestimated only for plants that were 15N-fed by fortnightly pulses, and not in plants 15N-fed continuously. This phenomenon was especially observed for plants that rely on symbiotic N2 fixation for N acquisition, and it may be linked to the concentration of the labelling solution. In conclusion, the assessment of nitrogen rhizodeposition was more reliable when plants were labelled continuously with a dilute solution of 15N urea. 相似文献
8.
Production of sheep (nursing ewes) grazing alternately with cattle (growing weaned heifers) was compared to the production
of sheep or cattle grazing alone (controls). Pasture production and sheep parasitism were also monitored. The herbage allowance
was higher for the control heifers than for the alternate heifers, but the leaf to green material ratio (LGMR) was lower,
and no difference on heifer growth was revealed (443 vs. 431g.d-1, P = 0.54). The LGMR was higher for the alternate sheep (+3 points) than for the control sheep, except during the dry season,
when the herbage density was lower. The effects of parasitism on the packed cell volume of alternate ewes and lambs were lower
than those of control ewes and lambs. However, the infection of sheep by Cooperia sp. (better adapted to cattle) was significantly higher for the alternate sheep than for the controls, and some indication
of cattle infection by Haemonchus contortus was suggested. The 70-day lamb weight was higher in the alternate grazing system than in the control (+0.76,+1.11 and+0.61kg
for the dry, intermediate and rainy seasons, respectively), and the average 70-day lamb production per ewe exposed was 21.42kg
in the alternate grazing system vs. 18.59kg in the control (P = 0.003). 相似文献
9.
Jose Escarr�� Claude Lef��bvre Stephan Raboyeau Anabelle Dossantos Wolf Gruber Jean Claude Cleyet Marel Helene Fr��rot Nausicaa Noret Stephanie Mahieu Christian Collin Folkert van Oort 《Water, air, and soil pollution》2011,216(1-4):485-504
Mining activities generate spoils and effluents with extremely high metal concentrations of heavy metals that might have adverse effects on ecosystems and human health. Therefore, information on soil and plant metal concentrations is needed to assess the severity of the pollution and develop a strategy for soil reclamation such as phytoremediation. Here, we studied soils and vegetation in three heavily contaminated sites with potential toxic metals and metalloids (Zn, Pb, Cd, As, TI) in the mining district of Les Malines in the Languedoc region (southern France). Extremely high concentrations were found at different places such as the Les Aviniéres tailing basins (up to 160,000 mg kg?C1 Zn, 90,000 mg kg?C1 Pb, 9,700 mg kg?C1 of As and 245 mg kg?C1 of Tl) near a former furnace. Metal contamination extended several kilometres away from the mine sites probably because of the transport of toxic mining residues by wind and water. Spontaneous vegetation growing on the three mine sites was highly diversified and included 116 plant species. The vegetation cover consisted of species also found in non-contaminated soils, some of which have been shown to be metal-tolerant ecotypes (Festuca arvernensis, Koeleria vallesiana and Armeria arenaria) and several Zn, Cd and Tl hyperaccumulators such as Anthyllis vulneraria, Thlaspi caerulescens, Iberis intermedia and Silene latifolia. This latter species was highlighted as a new thallium hyperaccumulator, accumulating nearly 1,500 mg kg?C1. These species represent a patrimonial interest for their potential use for the phytoremediation of toxic metal-polluted areas. 相似文献
10.
Mahieu Stéphanie Novak Sandra Barre Philippe Delagarde Rémy Niderkorn Vincent Gastal François Emile Jean-Claude 《Agroforestry Systems》2021,95(7):1295-1308
Agroforestry Systems - In temperate regions, tree leaves could be a source of energy, protein, vitamins and minerals for ruminants. Our objective was to study the diversity in chemical composition... 相似文献