Lack of microbiological contamination from bovine in vitro f ertilized embryos

Le but de cette étude était de connaître la nature et l’ampleur de la contamination éventuelle des embryons bovins fécondés in vitro à partir d’ovocytes prélevés à l’abattoir. Vingt-neuf vaches d’origine et d’âge non déterminés, à un stade quelconque de leur cycle sexuel ont été l’objet des prélèvements suivants : sang veineux périphérique (10 ml), ovocytes imma tures, liquides folliculaires et cellules d’oviducte, à des fins de recherches sérologiques (Brucellose, Leucose bovine enzootique, 1BR/1PV, BVD/MD) bactériennes ou virales (BHV 1 ; BVD/MD V). Parmi les 29 vaches, une a présenté une réaction sérologique positive vis-à-vis de la Brucellose, 2 une réaction positive vis-à-vis de la Leucose, 5 une réaction positive vis-à-vis de l’IBR/IPV et 21 une réaction positive vis-à-vis de la BVD/MD. Aucun animal n’a été trouvé virémique à la recherche du virus BVD/MD. Aucun agent bactériologique ou viral n’a été retrouvé sur les prélèvements du tractus génital, sur les œufs non segmentés ou sur les embryons. Ces observations sont compatibles avec l’absence de risques sanitaires que pourrait présenter la remise en place sur des receveuses, d’embryons fécondés in vitro issus d’ovocytes prélevés en abattoir.The aim of the present survey was to study the possible microbiological contamination of in vitro fertilized ova/embryos from oocytes collected at the abattoir. A total of 29 cows were submitted to various samplings. They were of undetermined origine, age and at any stage of their reproductive cycle. Sampling included blood from peripheral veins (10 ml), immature oocytes, follicular fluids, oviductal cells for serological (Brucellosis, Leucosis, IBR/ IPV, BVD/MD) or bacteriological or viral analysis (BHV 1; BVD/MD V). Non cleaved ova (n = 78) or embryos (n = 66) up to a maximal blastocyst stage, were obtained by total in vitro procedure. Among the 29 cows, some were serologically positive as follows: Brucellosis, 1; Leucosis, 2; IBR/IPV, 5; BVD/MD, 21. None were BVD/MD virus positive from blood samples. No bacterial nor viral contamination was found from uncleaved ova or from IVF embryos. The present observations are consistent with the possible lack of risks of contamination from IVF embryos originating from oocytes collected at the abattoir

Effects of in vitro contamination by Brucella Abortus on mice and cows embryos

On a cultivé in vitro des embryons de souris et de vache, à zone pellucide intacte, dans des milieux contenant 101 à 105 brucella par mi pour tester la viabilité et les risques de contamination de ces embryons après contact prolongé de 24 h et 48 h. Il en ressort que : — pour de faibles concentrations en brucella (101 à 102 b/ml), la viabilité des embryons est peu modifiée par rapport aux témoins ; — dans nos conditions expérimentales, aucun embryon n’a été conta miné après 48 heures de contact quelle que soit la concentration en brucella et en particulier celles-ci ne sont pas adsorbées sur la zone pellucide ; — dix lavages successifs des embryons contaminés, même à des concentrations elevées sont suffisants pour éliminer les brucella du milieu de transfert (effet dilution) à condition de respecter le protocole proposé. En conclusion, il paraît possible d'utiliser des vaches brucelliques de haute valeur génétique comme donneuses d’embryons, sans risque de transmission de cette maladie aux receveuses et aux futurs produits.In vitro cultures of mice (as a model) and cows embryos with intact zona pellucida have been performed in media containing 101 to 105 brucella per ml. This was aimed at evaluating both viability and risks of contamination of these embryos after 24 or 48 h of such cultures. It was found : (1) with low concentrations of brucella (101 - 10- b./ml, embryo viability was not affected when compared to that of controls ; (2) in our experimental conditions, no embryo was found to be contaminated after 48 h whatever was the brucella concentration in the culture medium ; in particular, brucella were not adsorbed on the zona pellucida ; (3) ten consecutive washings of the embryos initially inserted in a brucella-infected medium (at any of the concentrations studied) are definitely sufficient to eliminate all brucella from the transfer medium under strict conditions defined in the present paper. In conclusion, embryos from cows with high breeding values but unfortunately affected with brucellosis may be transferred with no risk of contamination neither to the embryo nor to the recipient

Maturation and fertilisation of sheep oocytes cultured in serum-free medium containing silk protein sericin

Sericin is a water-soluble component of silk and has been used as a biomaterial due to its antibacterial and ultraviolet radiation-resistant properties. This study was designed to evaluate the effect of sericin supplementation in a maturation medium on the meiotic competence and fertilisability of sheep oocytes. Cumulus-oocyte complexes (COCs) were cultured in TCM199 supplemented with sericin at various concentrations of 0 (control), 0.1, 0.25 and 0.5%, either with or without bovine serum albumin (BSA). When the COCs were matured without BSA, the supplementation of 0.1% sericin significantly increased the rates of maturation to metaphase II and the total fertilisation of oocytes compared with the other concentrations of sericin. When the COCs were matured with BSA, the beneficial effects of 0.1% sericin supplementation on the maturation and fertilisation of oocytes were not observed. Our findings indicate that supplementation with 0.1% sericin during maturation culture may improve the nuclear maturation and fertilisability of sheep oocytes. Moreover, it may be possible to replace BSA with sericin in chemically defined media without the risk of disease transmission

Coupling models of cattle and farms with models of badgers for predicting the dynamics of bovine tuberculosis (TB)

Bovine TB is a major problem for the agricultural industry in several countries. TB can be contracted and spread by species other than cattle and this can cause a problem for disease control. In the UK and Ireland, badgers are a recognised reservoir of infection and there has been substantial discussion about potential control strategies. We present a coupling of individual based models of bovine TB in badgers and cattle, which aims to capture the key details of the natural history of the disease and of both species at approximately county scale. The model is spatially explicit it follows a very large number of cattle and badgers on a different grid size for each species and includes also winter housing. We show that the model can replicate the reported dynamics of both cattle and badger populations as well as the increasing prevalence of the disease in cattle. Parameter space used as input in simulations was swept out using Latin hypercube sampling and sensitivity analysis to model outputs was conducted using mixed effect models. By exploring a large and computationally intensive parameter space we show that of the available control strategies it is the frequency of TB testing and whether or not winter housing is practised that have the most significant effects on the number of infected cattle, with the effect of winter housing becoming stronger as farm size increases. Whether badgers were culled or not explained about 5%, while the accuracy of the test employed to detect infected cattle explained less than 3% of the variance in the number of infected cattle

Subacute ruminal acidosis reduces sperm quality in beef bulls

Breeding bulls are commonly fed high-energy diets, which may induce subacute ruminal acidosis (SARA). In this experiment, 8 Santa Gertrudis bulls (age 20 ± 6 mo) were used to evaluate the extent and duration of effects of SARA on semen quality and the associated changes in circulating hormones and metabolites. The bulls were relocated and fed in yards with unrestricted access to hay and daily individual concentrate feeding for 125 d before SARA challenge. Semen was collected and assessed at 14-d intervals before the challenge to ensure acclimatization and the attainment of a stable spermiogram. The challenge treatments consisted of either a single oral dose of oligofructose (OFF; 6.5 g/kg BW) or an equivalent sham dose of water (Control). Locomotion, behavior, respiratory rate, and cardiovascular and gastrointestinal function were intensively monitored during the 24-h challenge period. Rumen fluid samples were retained for VFA, ammonia, and lactate analysis. After the challenge, semen was then collected every third day for a period of 7 wk and then once weekly until 12 wk, with associated blood collection for FSH, testosterone, inhibin, and cortisol assay. Percent normal sperm decreased in bulls dosed with OFF after the challenge period (P < 0.05) and continued to remain lower on completion of the study at 88 d after challenge. There was a corresponding increase in sperm defects commencing from 16 d after challenge. These included proximal cytoplasmic droplets (P < 0.001), distal reflex midpieces (P = 0.01), and vacuole and teratoid heads (P < 0.001). Changes in semen quality after challenge were associated with lower serum testosterone (P < 0.001) and FSH (P < 0.05). Serum cortisol in OFF bulls tended to be greater (P = 0.07) at 7 d after challenge. This study shows that SARA challenge causes a reduction in sperm quality sufficient to preclude bulls from sale as single sire breeding animals 3 mo after the event occurred