G. Aumont

French National Institute for Agricultural Research, Lutetia Parisorum, Île-de-France, France

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Publications (55)64.83 Total impact

  • Maurice Mahieu · Gilles Aumont
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    ABSTRACT: 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).
    No preview · Article · Jun 2008 · Tropical Animal Health and Production
  • Maurice Mahieu · Gilles Aumont

    No preview · Article · Sep 2007 · Tropical Animal Health and Production
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    ABSTRACT: The effect of age of regrowth (AR) of pasture herbage on milk production of Creole goats and growth rate of their kids while grazing irrigated Digitaria decumbens pastures was studied in Guadeloupe. Eighty-four does were used in an experiment to compare two rotational grazing systems over a one-year period during three kidding seasons classified as rainy, dry and intermediate. System AR21 allowed seven days of grazing and 21 days of regrowth whereas system AR35 allowed seven days and 35 days, respectively. An annual average stocking rate of 1,800 kg live-weight/ha was maintained in both systems. Dry matter (DM) yields were higher (P < 0.01) in the AR35 than in the AR21 system over the three seasons (4,935 vs. 2,948 kg/ha).Total biomass in the paddocks at the start of each grazing cycle varied between 11 and 19 DM kg/animal, depending significantly (P < 0.01) on the season. Age of regrowth had no effect. Daily milk production (938 to 1,033 g) also varied with the season but did not differ according to AR. Average daily gain (ADG) of kids in the AR21 system was lower by 23% than that of kids under the AR35. These differences were greater when ADG was adjusted for birth weight and milk production of the dam. Results may have been complicated by differences in gastro-intestinal parasitism, but this experiment showed that lowering AR of Digitaria decumbens pastures managed under intensive conditions did not significantly improve animal performance.
    No preview · Article · Jul 2007 · Journal of Agriculture- University of Puerto Rico
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    ABSTRACT: The study was undertaken in a Creole goat flock at INRA-Gardel in Guadeloupe, to evaluate the opportunity to use artificial selection as a means of controlling gastro-intestinal infection during early lactation. The flock grazed all year on Digitaria decumbens pastures. Faecal and blood samples were taken from kids at 11 months of age and from does at kidding before drenching (week 0) and at weeks 4 and 6 after kidding. Faecal egg counts (FEC) were estimated using a modified McMaster method. Blood samples were used to determine packed cell volume (PCV) and eosinophil concentrations (EOS) values. Haemonchus contortus, Trichostrongylus colubriformis and Oesophagostomum columbianum were the main strongyle species identified in faecal cultures. The data came from 1092 litters obtained from 688 does sired by 142 bucks and 413 dams. Variance and covariance components for genetic and residual effects were estimated with multivariate animal models using the restricted maximum likelihood VCE package. Repeatability and overall heritability for FEC during the post-partum period were 0·17 and 0·10±0·02. The genetic correlations between FEC and PCV were −0·56±0·11 at 4 weeks after kidding and −0·79±0·13 at 6 weeks after kidding. The genetic correlations between FEC and EOS were 0·37±0·15 at 4 weeks after kidding and 0·68±0·17 at 6 weeks after kidding. Hence, does that contributed least to pasture contamination during the postpartum period also had low EOS and high PCV breeding values. The genetic correlations between FEC measured at 11 months of age and FEC during periparturient period ranged from 0·57±0·12 to 0·76±0·16. Therefore, breeding goats for increased resistance during the post-weaning period will lead to a less marked and less persistent rise in doe FEC during early lactation. The epidemiological implications of this selection have to be quantified in terms of lower pasture contamination, lower kid parasitism, and higher milk production of does.
    Full-text · Article · May 2006
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    ABSTRACT: 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.
    Full-text · Article · Jan 2006 · Veterinary Parasitology
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    ABSTRACT: Seasonality of ovulatory activity is observed in European sheep and goat breeds, whereas tropical breeds show almost continuous ovulatory activity. It is not known if these tropical breeds are sensitive or not to temperate photoperiod. This study was therefore designed to determine whether tropical Creole goats and Black-Belly ewes are sensitive to temperate photoperiod. Two groups of adult females in each species, either progeny or directly born from imported embryos, were used and maintained in light-proof rooms under simulated temperate (8 to 16 h of light per day) or tropical (11 - 13 h) photoperiods. Ovulatory activity was determined by blood progesterone assays for more than two years. The experiment lasted 33 months in goats and 25 months in ewes. Marked seasonality of ovulatory activity appeared in the temperate group of Creole female goats. The percentage of female goats experiencing at least one ovulation per month dramatically decreased from May to September for the three years (0%, 27% and 0%, respectively). Tropical female goats demonstrated much less seasonality, as the percentage of goats experiencing at least one ovulation per month never went below 56%. These differences were significant. Both groups of temperate and tropical Black-Belly ewes experienced a marked seasonality in their ovulatory activity, with only a slightly significant difference between groups. The percentage of ewes experiencing at least one ovulation per month dropped dramatically in April and rose again in August (tropical ewes) or September (temperate ewes). The percentage of ewes experiencing at least one ovulation per month never went below 8% and 17% (for tropical and temperate ewes respectively) during the spring and summer months. An important seasonality in ovulatory activity of tropical Creole goats was observed when females were exposed to a simulated temperate photoperiod. An unexpected finding was that Black-Belly ewes and, to a lesser extent, Creole goats exposed to a simulated tropical photoperiod also showed seasonality in their ovulatory activity. Such results indicate that both species are capable of showing seasonality under the photoperiodic changes of the temperate zone even though they do not originate from these regions.
    Preview · Article · Sep 2004 · BMC Physiology
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    ABSTRACT: The efficacy of injectable levamisol, a mixture of levamisol and niclosamide, oral ivermectin, injectable ivermectin, oral albendazole and albendazole sulphoxide was evaluated in two farms with the dose recommended by the manufacturer. In the LABIOFAM farm 72 commercial sheep (uncontrolled crossbred Suffolk and Pelibuey) and in the Dos Mercedes farm 77 pure Pelibuey sheep were used. The selection of the animals was made according to their weight and an initial faecal egg count (FEC) superior to 100 eggs per gram (EPG). Animals were randomly divided into seven groups: LV (injectable levamisol), NC (tetramisol and niclosamida), LB (injectable ivermectin), IO (oral ivermectin), AZ (albendazol), LZ (albendazole sulphoxide) and C untreated control group. The FEC was carried out 14 and 4 days before, and the day of, drenching to assess the level of parasitic infection. A faecal egg count reduction test (FECRT) was performed at the 11th day to all groups. Three days after drenching two animals per group were slaughtered to determine the worm burden in each group. The results obtained showed evidences of Haemonchus spp. in LABIOFAM and Trichostrongylus spp. in Dos Mercedes for LV and NC, respectively. These results were reinforced with the predominance of each genus when helminthological necropsies were carried out. The efficacy of the other products (LB, LZ, AZ and IO) did not differ among them at the 11th day after drenching. These results indicate that the imidazotiazole group has showed a low level of anthelmintic resistance reached a questionable efficacy, but the rest of the products seem to be effective against gastrointestinal parasitism in sheep.
    Full-text · Article · Aug 2004 · Small Ruminant Research
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    ABSTRACT: Most pharmacokinetic studies on anthelmintic drugs have been performed on non-parasitized animals. However, it seems likely that the parasite burden could influence the deposition of such drugs. The pharmacokinetics of moxidectin administered orally and by subcutaneous injection was compared in lambs exposed to nematode infection and in parasite naive lambs. Plasma samples were analyzed for moxidectin over 40 days post-treatment. The main pharmacokinetic parameters calculated demonstrated a significant change in drug deposition in infected lambs when compared to controls. The area under the plasma concentration-time curve was decreased 54% and 46% by infection in the subcutaneous and oral groups, respectively. There was also a major decrease in the mean residence time in parasitized lambs. In parallel, the clearance of the drug was increased by infection. Thus, parasite infection dramatically influences the disposition of moxidectin in lambs. These results may contribute to determining a therapeutic strategy adapted to heavily infested animals.
    Full-text · Article · Jul 2004 · Parasitology Research
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    ABSTRACT: The litter size (LS), or its equivalent the number of kids born in the litter (NB), of Creole goats in Guadeloupe was studied by two procedures. The first approach considered LS as a single trait and as a characteristic of the mother of the litter, and was studied by an univariate animal model (UAM). The second procedure treated NB, the individual birth weight (BW) and loss of kids (LK) as traits belonging to the animals born in the litter and their dam, in a multitrait animal model (MAM). The heritability for genetic direct effect (h 2 a) for LS estimated by UAM (0·14) was 40% lower than the corresponding value for NB estimated by MAM. The most appropriate of the 6 MAMs tested estimated heritabilities (h 2 a) of 0·24, 0·22 and 0·17 for NB, BW and LK, respectively, while maternal effects (h 2 m) were 0·20, 0·24 and 0·09 for the same characters. The genetic correlations between direct and maternal effects (r am) were negative –0·611 and –0·725 for NB and LK, respectively, and not significantly different from zero for BW. This study explored the possibility of using the information on NB, BW and LK recorded in each animal born in the litter in order to analyse the genetic variability of these traits.
    Full-text · Article · Dec 2003 · Animal Science
  • G Aumont · L Gruner · G Hostache
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    ABSTRACT: The resistance of a tropical breed of sheep towards the nematode parasite Haemonchus contortus (Hc) was compared to that of a European breed after artificial infection with the parasite following a 2 x 2 x 2 experimental design: two isolates (Hc Gua from Guadeloupe versus Hc Fra from France), two breeds each reared in their native habitats (Black Belly (BB) in Guadeloupe, FWI, INRA 401 reared in France), and two groups of lambs with differing infection status (one naive, i.e. infected for the first time during the experiment, and one primed, i.e. which had previously received doses of 5000 L3 on Days -35 and -32 before the infection during this experiment). Both groups were composed of 10 male lambs, which were 20 weeks of age when they were given a dose of 10,000 L3 of the relevant isolate on Day 0. Resistance was assessed by regular fecal egg counts (FECs) and blood samples, and worm counts were processed on Day 35 p.i. The FEC was lower in the BB than in INRA 401 lambs, lower in the primed than naive groups, and lower in Hc Fra than in Hc Gua. The eosinophil count remained unchanged in the naive INRA 401 groups, but increased in all the other groups. The hematocrit fell after infection, but the live weight was not affected by the infection. Worm burdens were 1868 and 5237 in the naive BB and INRA 401 groups, respectively, and 596 and 4835 in the primed BB and INRA 401 groups. The daily production of eggs per Hc Gua female worm was 1.5-fold that of Hc Fra. The number of worms had no effect on worm length or Hc in utero egg count in the BB sheep, but a positive and significant correlation between these two traits was seen in the INRA 401 lambs. These findings are indicative of innate resistance, and confirmed the high acquired resistance of the BB sheep to both sympatric and allopatric isolates of Hc. The regulation of worm population and fecundity differed in the BB and INRA 401 sheep.
    No preview · Article · Nov 2003 · Veterinary Parasitology
  • N Mandonnet · V Ducrocq · R Arquet · G Aumont
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    ABSTRACT: Mortality due to strongyles infection in small ruminants is a critical component of flock productivity in a tropical climate. In goat production, few experiments have been conducted to estimate the variability of this trait. A survival analysis study was carried out in the Creole experimental flock of INRA-Gardel (Moule, Guadeloupe) to identify management and genetic factors influencing mortality of kids reared at pasture and infected with gastrointestinal strongyles, predominantly Haemonchus contortus and Trichostrongylus colubriformis. Survival curves from 3 and 11 mo of age were analyzed for 837 kids sired by 48 bucks and 250 does. The causes of death were recorded. Mortality due to gastrointestinal strongyles was the variable considered. The flock management included drenchings with levamisole every 8 wk. Fecal egg counts and packed cell volume were regularly measured after 7 wk of natural infection. All but 6.7% of the records were uncensored, with an average failure time of 165 d. The probability of death following gastrointestinal infection was more than three times greater in males than in females. Kids raised by their mother before weaning had a lower (P < 0.05) relative risk of dying than those reared in nursery (0.40 vs. 1). Parity of the dam and litter size effects were not significant. The risk of death was reduced by approximately 80% during the 3 wk that followed a drenching (P < 0.01). Risk decreased by about 25% for each additional kilogram of body weight at weaning. Live weight, fecal egg counts, and packed cell volume all had significant effects on risk of death when introduced as time-dependent covariates in the model (P < 0.0001 for live weight and packed cell volume, and P < 0.01 for fecal egg counts). The estimated genetic variability was small and inaccurate. These results demonstrated that risk of death from gastrointestinal infection could be reduced with appropriate flock management. High infection levels increased the risk of death, but they were not the direct cause. The important mediation of reduced body weight and anemia in likelihood of death is highlighted. More data are needed to better assess the possibility for genetic improvement of viability in Creole kids during gastrointestinal strongyle infection.
    No preview · Article · Oct 2003 · Journal of Animal Science
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    ABSTRACT: Compared to INRA 401 lambs reared in France, Black Belly (BB) lambs reared in Guadeloupe (F.W.I.) were highly resistant to both primary and secondary experimental infection with Haemonchus contortus. To investigate this huge inter-breed difference, a nucleus flock of BB was constituted, and experiments were conducted to: (i) confirm this difference in lambs born in France, (ii) check whether it was similar for Trichostrongylus colubriformis and Teladorsagia circumcincta, and (iii) find out whether this difference was age-related. Forty BB lambs, 84 F1 lambs (BB sires×INRA 401 ewes) and 88 INRA 401 lambs born in two cohorts were used in an experimental design involving three host breeds, both genders and two age-groups (3.5- and 7-month-old when first infected). The limited availability of BB lambs made the study incomplete. Infection consisted of the administration of two doses of 10 000 infective larvae of one of the nematode species, separated by an anthelmintic treatment and an interval of 1 week before the second dose was administered. Fecal egg counts (FECs) were done on Days 28 and 35 after each infection; ewe lambs of the INRA 401 and F1 breeds were necropsied, the worm burden was established, the length of the female worms measured and the eggs in utero counted.
    No preview · Article · Oct 2003 · Veterinary Parasitology
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    ABSTRACT: Goat production is widespread in the tropics. Goats are very susceptible to gastrointestinal nematode infection, but there is less evidence of their genetic resistance. Genetic resistance of Creole goats to gastrointestinal nematodes has been studied at Guadeloupe in the French West Indies since 1995. The objective of this research was to investigate genetic variation for resistance to gastrointestinal nematode infection, in order to introduce this trait into breeding schemes. Genetic variability was assessed within a Creole experimental flock. Forty-nine sire groups were characterized at weaning and 55 during fattening after weaning. Kids were naturally infected, mainly by Haemonchus contortus and Trichostrongylus colubriformis. Fecal egg counts were determined once at weaning and every 6 and 7 wk after drenching during fattening. Blood samples were collected every 7 wk during fattening for determination of packed cell volume. Live weights were recorded at weaning and at the beginning and middle of every infection period during fattening. Genetic parameters were estimated using the REML for multivariate animal models. The heritability estimate for transformed fecal egg count was 0.37+/-0.06 at weaning. During fattening, it increased from 0.14+/-0.05 at 4 mo to 0.33+/-0.06 at 10 mo. Heritabilities of packed cell volume ranged from 0.10 to 0.33. At weaning, maternal heritability of fecal egg count reached 0.26 and direct heritability 0.20. After 6 mo of age, maternal effects were found to be unimportant for fecal egg count and packed cell volume. Live weights presented significant genetic variability. Genetic relationships between fecal egg counts and live weight in infected pastures were never significant. Genetic correlations between packed cell volume and live weight decreased from 0.47 to 0.10 from weaning to 10 mo of age. These results demonstrated the feasibility of breeding for improved resistance to nematodes in Creole kids.
    Preview · Article · Aug 2001 · Journal of Animal Science
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    Eric Chevaux · Gilles Aumont

    Preview · Article · May 2001 · Annales de Zootechnie
  • G. Alexandre · M. Mahieu · G. Aumont
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    ABSTRACT: Le potentiel de production du mouton Martinik et de la chèvre Créole de Guadeloupe a été évalué en station. Les conditons d'élevage semi-intensives étaient basées sur un rythme de 3 mises-bas en 2 ans, sur l'utilisation de pâturages irrigués et fertilisés, exploités à fort chargement animal (1.6 t/ha) et en rotation et sur l'application d'une prophylaxie rigoureuse et adaptée. Les brebis Martinik et les chèvres Créole sont caractérisées par une très bonne fertilité (85 vs 92%), une prolificité élevée (1.7 vs 2.1) et une mortalité pré-sevrage réduite (10 vs 16%) qui les classent parmi les meilleurs génotypes tropicaux. La chèvre Créole présente comparativement à la Brebis Martinik une supériorité quant à sa productivité numérique annuelle: 2.90 vs 2.17 jeunes/femelle à la naissance ou 2.44 vs 1.97 au sevrage. Le même paramètre rapporté à l'unité de surface varie de 174 à 87 jeunes/ha à la naissance, ou de 147 à 78 au sevrage, respectivement pour les chèvres et les brebis. A l'inverse, le système ovin génère une productivité pondérale largement supérieure à celui des caprins avec 27.9 vs. 19.5 kg de jeunes sevrés/femelle/an ou encore 1 400 vs 1 130 kg de jeunes produits post-sevrage/ha/an. D'autres paramètres sont présentés dans le papier et une discussion est menée sur l'intérêt respectif des deux espèces pour le développement de la production de viande en zone tropicale. En effet le système allaitant est prometteur avec une productivité, quelle que soit l'espèce animale, de 1.3 t de jeunes sevrés/ha/an.
    No preview · Article · Apr 2001
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    ABSTRACT: Experiments were carried out to determine the effects of supplementation upon milk production and growing performances of Martinik hair sheep. Ewes weighing 49 kg LW were used in a 2-season experimental study. In the first trial, 3 energy supplement levels were offered to ewes suckling single lambs. The adjusted level (A, 8 ewes) was supplied to ensure that the litter had a daily weight gain (DWG) of 250 g. High (H, 8 ewes) and low (L, 8 ewes) levels were 150% and 75% of level A, respectively. In the second trial, comparative use of the H level was studied with 3 animal requirement levels: ewes suckling single lambs (SI, same ewes as H ewes), twins (TW, 8 ewes) and triplets (TR, 6 ewes), respectively. The experimental design was replicated in a second lambing season. The basal diet was chopped Digitaria decumbent hay (0.6 UFL, 4.6% CP) offered ad libitum. Supplements were composed of maize (65%), soya bean (3%), fish meal (8%) and dehydrated alfalfa (24%). The milk production (MP) of ewes on the L diet was losver (P < 0.05) than that of ewes on the A and H diets: 1142, 1415 and 1518 kg·d-1, respectively. H-fed ewes fattened during the lactating period while A and L ewes respectively maintained and lowered their body condition score (BCS). Differences recorded for lamb DWG were low, but this trait reached a maximum of 248 kg·d-1. MP varied significantly (P < 0.05) according to the litter size. Individual DWG was different for single, twin and triplet lambs (P < 0.001): 261, 188 and 143 kg·d-1, respectively. In intensive breeding conditions, recommended daily energy allowances taking into account a good BCS of ewes for successive reproduction are 1.47 UFL for single-suckling ewes and 2.17 UFL for twin-suckling ewes, in order to obtain a DWG of the litter of 250 and 400 kg·d-1, respectively.
    No preview · Article · Jan 2001
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    ABSTRACT: The selection of resistant sheep in farms could increase the selective pressure during the parasitic phase and this might affect life-traits of the parasite nematodes. Before selecting for host resistance, it is crucial to estimate the potential adaptation of these nematodes to resistant hosts. The objective of this study was to determine the ability of the nematode parasite Haemonchus contortus, to adapt its life-traits to different resistance states of sheep. The isolates of the nematode Haemonchus contortus were obtained from five locations in Guadeloupe (French West Indies) and a synthetic strain was prepared, which was representative of these isolates on the basis of isoenzymes and morphometric traits. This synthetic strain was reproduced during 10 generations in hosts of marked different resistance status. Primary infected 6-to 8-months old Black Belly ewe lambs, a wellknown to be highly resistant breed to nematode parasites, were used as resistant host. The "susceptible" lambs were obtained by treating with long-acting corticoids to depress the resistance of lambs. The establishment rate of worms and their egg-laying capacities were highly reduced in resistant lambs compared with susceptible ones. It can be assumed that the experimental design of infection apparently mimicked well the differences observed between genotypically resistant and susceptible sheep. To assess the adaptation, resistant, susceptible and naive lambs were infected with the two H. contortus lines, previously reproduced in resistant or susceptible sheep. The hosts were genetically related lambs (monozygotic twin lambs, within-litter brothers) allocated in an experimental plan designed to enhanced the power of the experiment. The use of monozygotic twins did not prove as useful as expected for parasitological data. There was no significant difference between the life-traits of the two lines. H. contortus did not seem to adapt to the resistance status of the host. Therefore, it was considered that selection for resistant sheep was possible with a limited risk of adaptation of the nematode parasites, although long-term monitoring of nematode adaptation should be scheduled if host selection is planned.
    No preview · Article · Jan 2001 · Genetics Selection Evolution
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    ABSTRACT: The intake and digestion of fresh Digitaria decumbens grass were studied following the stage of regrowth. Six rams (mean liveweight: 40.8±0.6kg) received successively a 14, 28, 42 and 56-day old forage during four 4-week periods. The range of variation of crude protein and acid detergent fibre content (g/kg) of the forages was 57–130 and 380–442, respectively. The DM intake (g/kgW0.75) and the organic matter total tract digestibility decreased from 83 to 56 and from 0.728 to 0.628, respectively, between 14 and 56 days of regrowth. The fractional degradation rate (h−1) of dry matter in the rumen, estimated by the nylon bag method, decreased curvilinearly with a mean daily rate of 0.0010. A curvilinear relationship was recorded between the rumen turnover rate and forage regrowth stage. The mean daily decrease (per hour per day) was 0.0005. The total nitrogen duodenal flow (g per day) decreased from 22.7 to 11.6 between 14 and 56 days. The mean efficiency of microbial protein synthesis was similar with the four diets (31.8, S.E. 2.2g microbial nitrogen/kg organic matter apparently digested in the rumen). In conclusion, intake, digestibility and duodenal nitrogen flow are high with the 14-day D. decumbens. As a consequence, the nutritive value of the latter is similar to the one of a good temperate grass forage. Good nutritive value of a 14-day old D. decumbens and fast maturation and lignification in C4 forage before the first month of regrowth suggest the need to investigate ruminant feeding strategies with forages younger (
    No preview · Article · Oct 2000 · Animal Feed Science and Technology
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    M Saulai · G Hostache · G Aumont · J Cabaret
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    ABSTRACT: Haemonchus contortus isolates were collected from goats of five locations with different climatic characteristics in Guadeloupe archipelago. They were investigated for morphology, morphometrics and allozyme diversity after passage in immunosuppressed lambs using long acting corticoids. The basic aim of the work was to construct a synthetic strain in laboratory conditions which was representative of the isolates. The isolates were only slightly different although climatic conditions were very different. The resemblance of isolates might be due to the practice of goat exchanges between farms or to their insular origin. However the isolate from a smaller island (Les Saintes) was different (mostly on morphometrics) from all the others originating from Guadeloupe main Island. The first assemblage in laboratory resulting from the installation from a mixture of the five isolates was not very representative, whereas the next generation (synthetic strain) resembled all the isolates as shown from allozyme study. Female fecundity and length in established synthetic strain were lower than that recorded in isolates, indicating a decrease in fitness, possibly due to the stability of experimental environment. The representativity of the synthetic strain was good but the strain could still evaluate on further passages and should be evaluated on a large number of generations maintained in laboratory.
    Full-text · Article · Apr 2000 · Parasite
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    Giudici CJ · G Aumont · M Mahieu · M Saulai · J Cabaret
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    ABSTRACT: 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.
    Full-text · Article · Nov 1999 · Veterinary Research