Impact of postovulatory food deprivation on the ova transport, hormonal profiles and metabolic changes in sows.

The effect of food deprivation on ova transport, hormonal profiles and metabolic changes was studied in 20 crossbred multiparous sows during their second oestrus after weaning. To determine the time of ovulation, transrectal ultrasonographic examination was performed. The sows were divided into 2 groups, one control group (C-group), which was fed according to Swedish standards, and one experimental group (E-group). The E-group sows were deprived of food from the first morning meal after ovulation until slaughter. Blood samples were collected every second hour from about 12 h before expected ovulation in the second oestrus after weaning until slaughter and were analysed for progesterone, prostaglandin F2 alpha-metabolite, insulin, glucose, free fatty acids and triglycerides. All sows were slaughtered approximately 48 h after ovulation and the genital tract was recovered. The isthmic part of the oviduct was divided into 3 equally long segments and flushed separately with phosphate buffered saline (PBS). Uterine horns were also flushed with PBS. A significantly greater number of ova were found in the first and second part of the isthmus in the E-group (p = 0.05) while in the C-group most of the ova were found in the third part of the isthmus or the uterus (p = 0.01). The level of prostaglandin F2 alpha-metabolite was significantly higher in the E-group compared with the C-group. The concentration of progesterone increased in both groups after ovulation but there were no significant differences between the groups. The other blood parameters showed that the food-deprived sows were in a catabolic state. The 48 h period of fasting results, directly or indirectly in an delayed ova transport, which may be due to a delayed relaxation in the smooth circular muscle layer of the isthmus.     

Neurotrophins and the Thymus: Morphological Analysis of Mice Carrying a Non-functional Mutation on the Trka and Trkb Genes

Veterinary Research Communications -     

Prevalence and clinical implications of anthelmintic resistance in cyathostomes of horses.

OBJECTIVE: To determine the prevalence and clinical implications of anthelmintic resistance in cyathostomes of horses. DESIGN: Prospective study. ANIMALS: 80 horses on 10 farms in a 5-county region of northeast Georgia. PROCEDURE: On each farm, horses were stratified in descending order according to pretreatment fecal egg count (FEC), blocked into groups of 4, and then randomly assigned to 1 of 4 treatment groups: no treatment (controls), and treatment with pyrantel pamoate, fenbendazole, or ivermectin. Fecal samples were collected 24 hours prior to treatment and 2, 4, and 6 weeks after treatment for determination of FEC. Mean percentage of reduction in FEC was then calculated for each treatment group. For horses from each farm, the efficacy of each anthelmintic was categorized on the basis of mean percentage of reduction in FEC at 2 weeks after treatment (< 80% reduction = ineffective; 80 to 90% reduction = equivocal; and > 90% reduction = effective). RESULTS: Pyrantel pamoate was effective at reducing FEC in horses from 7 farms, ineffective in horses from 2 farms, and equivocal in horses from 1 farm. Fenbendazole was ineffective at reducing FEC in horses from 9 farms and equivocal in horses from 1 farm. Ivermectin was effective at reducing FEC in horses from all 10 farms. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that cyathostome resistance to fenbendazole is highly prevalent, and resistance to pyrantel pamoate is high enough to warrant concern. Resistance to ivermectin was not detected. On the basis of these data, it appears that ivermectin continues to be fully effective in horses. However, too few farms were used in this study to determine the prevalence of cyathostome resistance to ivermectin. Therefore, the efficacy of ivermectin should continue to be monitored closely.     

Maladies de l'eucalyptus1

Les eucalyptus constituent—au moins au meme titre que les genres Pinus et Populus—l'un des genres d'arbres forestiers les plus importants à l'échelle mondiale, et en particulier par l'extension considérable des reboisements (plus de 4 millions d'ha) en régions tropicales, sahéliennes et tempérées chaudes. L'article tente de faire le point sur les problèmes posés par les maladies pouvant gener cet effort de reboisement, notamment en région méditerranéenne, et souligne l'importance et l'avenir des eucalyptus dans cette région. Il est procédéà un inventaire général, à l'échelle mondiale, des maladies des eucalyptus et de l'importance des parasites en cause. Un certain nombre d'entre eux sont étudiés plus en détail, selon qu'ils sont présents dans le pays d'origine des eucalyptus ou dans les zones où ils ont été introduits. Une section est réservée à la région méditerranéenne, où certaines maladies s'en prenant aux racines, aux rameaux, aux feuilles ou au bois ont été identifiées; pour l'instant, la plupart d'entre elles ne sont pas trop graves. Enfin, des propositions et des règles de protection phytosanitaire, visant à restreindre les risques d'introduction des parasites les plus dangereux ou d'extension de ceux existant actuellement, sont citées, en insistant sur les risques de transport de maladies d'une région à une autre par l'intermédiaire des échanges de matériel végétal autres que les graines.     

Alfalfa Phytoestrogen Content: Impact of Plant Maturity and Herbage Components

Legumes contain a range of non‐nutritional phytochemicals that may have health‐promoting effects in humans. In this study, we determined the concentrations of four phytoestrogens (coumestrol, apigenin, luteolin and quercetin) in field‐grown alfalfa (Medicago sativa L.). Differences between plants of different stages of maturity, between plant parts, and different canopy segments were assessed. The concentration of individual phytoestrogen in whole herbage varied between 15 and 225 μg g^?1 dry matter (DM) and was strongly affected by stage of maturity. Coumestrol and apigenin concentrations were highest at early vegetative stages, luteolin and quercetin at early vegetative and late flowering stages. All phytoestrogens were found in lowest concentrations at the early flowering stage (average 68 μg g^?1 DM); stage at which alfalfa is usually harvested when used as a forage source for animals. At vegetative stages, apigenin was the predominant phytoestrogen in herbage followed by coumestrol, the reverse being observed upon initiation of flowering; luteolin and quercetin were found at all stages in similarly lower concentrations. Concentrations of luteolin, quercetin and apigenin were 225, 410 and 690 % greater, respectively, in flowers than in leaves or stems; coumestrol concentration was similar between plant parts. In flowers and stems the predominant phytoestrogens were apigenin and quercetin, followed by coumestrol and luteolin. Similar concentrations (average 26 μg g^?1 DM) of each of the four phytoestrogens were found in leaves. Concentrations through the herbage canopy varied and were greatest at >60 cm from the soil surface for apigenin and coumestrol, but greatest at >60 and 0–20 cm for quercetin and at 0–20 cm for luteolin. The results suggest that if alfalfa is to be used as a source of phytoestrogens and is harvested for the production of herbal supplements or nutraceuticals, management will need to be adapted.     

Inflammatory mammary carcinoma in dogs: 33 cases (1995-1999).

OBJECTIVE: To determine epidemiologic, clinical, and pathologic characteristics of inflammatory mammary carcinoma (IC) in dogs. DESIGN: Retrospective study. ANIMALS: 33 dogs with IC and 153 dogs with malignant mammary tumors other than IC. PROCEDURES: Medical records were reviewed, and signalment, history, physical examination findings, and results of thoracic radiography and necropsy were obtained. RESULTS: 33 of 436 (7.6%) dogs examined at a veterinary teaching hospital because of dysplasia or tumors of the mammary glands and 33 of 186 (17.7%) dogs with at least 1 malignant tumor had IC. Thirty-two of the 33 dogs were sexually intact. Dogs with IC were significantly older than were dogs with other malignant mammary tumors, and in dogs with IC, the tumor was initially noticed a mean of 52 days after the beginning of the last observed estrus, whereas in dogs with other mammary tumors, the tumor was initially noticed a mean of 137 days after the beginning of the last observed estrus. Dogs with IC were more likely to be anorectic and to have generalized weakness, weight loss, and thoracic metastases. Dogs with IC survived a mean of 25 days with palliative treatment. Histologically, involvement of dermal lymphatic vessels was identified in 14 of 19 (74%) dogs with IC. Two clinical forms of IC (primary and secondary) were identified. Dogs with primary IC had a worse clinical condition. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that IC is an uncommon but distinct entity in dogs. A histologic finding of dermal lymphatic involvement should be considered a hallmark for the pathologic diagnosis of IC in dogs.     

Effect of Oestrous Synchronization with Estradiol 17β and Progesterone on Follicular Wave Dynamics in Dairy Heifers

An experiment was designed to evaluate the effects of estradiol‐17β (E17β) on follicular wave dynamics and ovulatory response in Holstein heifers receiving either a progestogen ear‐implant (Crestar^®; Intervet International b.v. Boxmeer, The Netherlands) or an intravaginal progesterone‐releasing device [controlled internal drug release‐bovine device (Eazibreed, CIDR‐B^®; Bodinco BV, Alkmaar, The Netherlands)]. For comparison, another group of heifers was also synchronized using Crestar plus an injection of estradiol valerate (EV) and norgestomet as recommended by the pharmaceutical company. Twenty 20–22‐month‐old cycling Holstein heifers were allocated to one of the following treatment groups at random stages of the oestrous cycle: (I) simultaneous insertion of Crestar and intramuscular injection of 3 mg norgestomet and 5 mg EV (Crestar 9 + EV 9); (II) simultaneous insertion of Crestar and intramuscular injection of 5 mg E17β (Crestar 9 + E17β 9); (III) insertion of Crestar followed 2 days later by intramuscular injection of 5 mg E17β (Crestar 9 + E17β 7); or (IV) insertion of CIDR‐B device followed 2 days later by intramuscular injection of 5 mg E17β (CIDR 9 + E17β 7). The CIDR‐B or Crestar implants were removed after 9 days and all heifers received 500 μg Cloprostenol (Estrumate^®, Pitman‐Moore Nederland BV, Houten, The Netherlands). Ovarian ultrasonographic examinations were performed once daily during the synchronization period using a B‐mode scanner equipped with a 7.5 MHz linear‐array transrectal transducer. In addition, heifers were scanned every 12 h after implant/device withdrawal until 3 days after ovulation in order to monitor follicular activity, detect ovulation and subsequent early luteal formation. Detection of oestrus was performed every 6 h for 4 days after device/implant removal. Oestrus was observed 24–32 h before ovulation in all heifers. The mean hours interval from treatment withdrawal to ovulation was not significantly different (84.0 ± 16.5, 77.6 ± 4.1, 73.6 ± 4.1 and 64.0 ± 4.4 h for treatments I, II, III and IV, respectively; p > 0.1). However, the variance for heifers treated with EV + norgestomet was significantly larger (Levene’s Test; p < 0.01) than those treated with E17β. All E17β treatments resulted in dominant follicle suppression and a new wave emerged 4.1 days after treatment compared with 6.6 days for the EV + norgestomet treatment (p < 0.05). The time from emergence of the new ovulatory wave to ovulation was longer for the new wave that emerged after E17β treatment (9.2 ± 0.3 days) than after EV + norgestomet treatment (6.9 ± 0.4 days; p < 0.05). The results of this study suggest that the four treatments used were effective in inducing synchronous behavioural oestrus and ovulation. However, a higher degree of oestrus and ovulation synchrony was observed in heifers treated with E17β than in heifers treated with EV + norgestomet. Synchronization treatments with exogenous E17β or EV + norgestomet at the time of progestin device insertion (Crestar or CIDR‐B) or 2 days later in heifers can regulate a different emergence pattern of ovarian follicular development in randomly cyclic heifers. The E17β was effective in inducing follicular suppression and resulted in the consistent emergence of a new follicular wave.     

Trends in mortality ratios among cattle in US feedlots.

OBJECTIVE: To evaluate trends in feedlot cattle mortality ratios over time, by primary body system affected, and by type of animal. DESIGN: Retrospective cohort study. ANIMALS: Approximately 21.8 million cattle entering 121 feedlots in the United States during 1994 through 1999. PROCEDURES: Yearly and monthly mortality ratios were calculated. Numbers of deaths were modeled by use of Poisson regression methods for repeated measures. Relative risks of death over time and by animal type were estimated. RESULTS: Averaged over time, the mortality ratio was 12.6 deaths/1,000 cattle entering the feedlots. The mortality ratio increased from 10.3 deaths/1,000 cattle in 1994 to 14.2 deaths/1,000 cattle in 1999, but this difference was not statistically significant (P = 0.09). Cattle entering the feedlots during 1999 had a significantly increased risk (relative risk, 1.46) of dying of respiratory tract disorders, compared with cattle that entered during 1994, and respiratory tract disorders accounted for 57.1% of all deaths. Dairy cattle had a significantly increased risk of death of any cause, compared with beef steers. Beef heifers had a significantly increased risk of dying of respiratory tract disorders, compared with beef steers. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggested that although overall yearly mortality ratio did not significantly increase during the study, the risk of death attributable to respiratory tract disorders was increased during most years, compared with risk of death during 1994. The increased rates of fatal respiratory tract disorders may also reflect increased rates of non-fatal respiratory tract disorders, which would be expected to have adverse production effects in surviving animals.     

Cryopreservation of Embryos of Farm Animals

This review contains two parts. The first part is devoted to the significant steps in cryopreservation of mammalian embryos with emphasis on cattle and sheep that serve as models of reference. These steps are: (1) shortening of cooling and warming processes; (2) addition and dilution of cryoprotectant in one step; (3) introduction of plastic straw as a freezing and dilution container; (4) the choice of ethylene glycol as the quite universal cryoprotectant because of its low toxicity and high permeability; (5) vitrification, a cryopreservation method which enable passage from the liquid to the solid state by extreme elevation of viscosity due to high concentration of cryoprotectants and very rapid cooling. There are several vitrification solutions which contain dimethyl sulphoxide, glycerol, ethylene glycol, or a mixture of them, as basic cryoprotectants. The second part considers some factors affecting the efficiency of cryopreservation concerning (i) the origin of embryos and (ii) the stage of development and species. The origin of embryos (in vivo versus in vitro): in vitro embryos show a chilling and freezing sensitivity associated with their lipid content which can be modified by the culture conditions. Both conventional freezing and vitrification have been used and it seems that vitrification is more adapted to in vitro embryos when some modifications of initial protocols are carried out, particularly the rate of cooling. Thus considerable progress has been achieved by using the open pulled straw method of Vajta which enables the use of a minimum volume of freezing medium (0.5 μl) and a very high cooling rate that permits rapid traversal of the damaging temperature zone, corresponding to chilling sensitivity. The stage of development and species: not only are there differences between species at the same stage of development but in the same species all stages of development do not survive equally under the same freezing protocol. In cattle for example, oocytes and early stages of development in vivo or in vitro do not survive whereas compacted morulae and blastocysts survive very well. In the pig hatched blastocysts survive better than the other stages. Horse embryos have special characteristics that pose problems for successful freezing. In conclusion, a lot of work remains to be done to define fundamental characteristics of embryos of certain species (pig, horse) and of embryos of some stages or of oocytes.