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SUMMARY Reproductive performance was compared between cows whose previous parturition was induced and non-induced cows with similar calving dates, in 49 winter-calving, pasture-fed, commercial dairy herds in south-western Victoria. Parturition was induced in winter when most cows were between 27 and 35 weeks of pregnancy. Reproductive performance was assessed during the next mating period after induction which was mainly in spring of the same year. Percentages of cows in induced and untreated groups that were not pregnant after the mating period (9.0% and 7.2%, respectively) did not differ significantly. Induction tended to increase the percentage of cows of unknown pregnancy status. Mean percentages for induced and untreated groups were 11.5% and 7.9%, respectively. Induced and untreated groups calved at similar intervals after the planned start of calving in the following year, and the percentages of groups that required induction in that year did not differ significantly. The direct effects of induced parturition on reproduction were therefore concluded to be minimal. In seasonal calving herds, improvements in reproductive performance could be expected among cows whose calving dates were altered substantially by induction, due to increased intervals from calving to mating start date .  相似文献   
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Summary The efficacy of morantel sustained release trilaminate (MSRT) bolus against gastrointestinal nematodes was evaluated under field conditions over a 10-month period. Twenty weaner calves were randomly divided into 2 groups of 10 calves each and grazed from March to December on adjacent, similarly contaminated paddocks. Group 1 calves (T-1) served as untreated controls while group 2 calves (T-2) were dosed at turnout with MSRT bolus designed to release morantel tartrate continuously for 90 days. The efficacy of MSRT was assessed by comparison of parasitological data (faecal worm egg counts, herbage larval counts, worm counts from tracer calves and set-stocked trial calves, determination of haematological parameters and pepsinogen levels), weight gains and clinical status of the animals. Faecal egg counts from the treated group (T-2) were reduced by 100% (P < 0·001) following treatment and remained significantly (P < 0·05) lower than counts from T-1 calves up to trial termination. The use of MSRT bolus resulted in a reduction of 92% (P < 0·001) in the number of gastrointestinal nematodes in set-stocked calves at the end of the study and a 55 to 85·7% reduction in herbage larval infectivity as reflected in lowered parasite burdens in tracer calves. At the trial termination, the control calves had gained on average (± s.d.) 59·4 ± 4·8 kg (200·0 ± 7·4 g day−1) and the treated ones on an average 128·6 ± 10·5 kg (530·0 ± 13·1 g day−1).
Eficacia De La Utilizacion De Bolos Trilaminados De Morantel Frente A Nematodos Gastrointestinales En Vacuno De Leche En Pastoreo En Kenya
Resumen Se evaluó la eficacia de los bolos trilaminados de liberación continua de morantel (MSRT) frente a nematodos gastrointestinales en condiciones de campo y durante un período de 10 meses. Un total de 20 terneros recién destetados fueron divididos al azar en dos grupos de 10 animales cada uno y mantenidos en pastoreo desde marzo hasta diciembre en parcelas adyacentes y con una carga parasitaria similar. Los terneros del grupo 1 (T-1) fueron los animales control y no recibieron ningun tratamiento, mientras que los terneros del grupo 2 (T-2) fueron tratados con MSRT al inicio del período de pastoreo; los MSRT estaban dise?ados para liberar tartrato de morantel de forma contínua durante 90 días. La eficacia de los MSRT se evaluó comparando datos parasitológicos (huevos en heces, larvas en el pasto, parásitos en los animales, parámetros hematológicos y niveles de pepsinógeno), ganancias de peso y datos clínicos. El número de huevos en heces en los animales T-2 se redujo en un 100% (P < 0·001) después del tratamiento y se mantuvo significativamente más bajo (P 0·05) que el de los animales T-1 durante todo el experimento. La utilización de MSRT resultó en una reducción del 92% (P < 0·001) en el número de nematodos gastrointestinales y en una reducción del 55 al 85·7% en el número de larvas en el pasto. La ganancia de peso final fue de 59·4 ± 4·8 kg en los animales T-1 (200·0 ± 7·4 g/día) y de 128·6 ± 10·5 kg en los animales T-2 (530·0 ± 13·1 g/día).

Efficacite Du Morantel Por Voie Orale Contre Des Nematodes Gastro-Intestinaux Chez Des Veaux Laitiers Au Kenya
Résumé L’efficacité du Morantel distribué par voie orale, contre des nématodes intestinaux fut évaluéein situ sur plus de 10 mois. 20 veaux sevrés furent répartis au hasard dans 2 groupes de 10 veaux chacuns et broutèrent de Mars à Décembre sur 2 parcelles adjacentes et contaminées de fa?on identique. Le premier groupe (T-1) servit de temoin alors que le deuxième groupe (T-2) re?ut du morantel de fa?on continue pendant 90 jours. L’efficacité du Morantel fut analysée par comparaison des données parasitologiques (nombre d’oeufs de nématode dans les faèces, nombre de larve dans l’herbe, nombre de nematodes chez des veaux de contr?le mobiles et non mobiles, determination des paramètres hématologiques et des tereurs en pepsinogène), des gains de poids et des caractéristiques cliniques des animaux. Le nombre d’oeufs dans les faeces furent réduits de 100% dans le groupe (T-2) (P < 0,001) après le traitement et perdura de fa?on significative (P < 0,05) en dessous des valeurs pour les veaux du groupe (T-1) et cela jusqu’à la fin de l’éxpérience. L’utilisation du Morantel par voie orale entra?na une réduction de 92% dans le nombre des nématodes intestinaux dans les veaux immobilisés à la fin de l’experimentation ainsi qu’une réduction de 55 à 85,7% des larves dans les herbages témoin d’une diminution des parasites rejetés par les animaux sentinels. A la fin de l’expérimentation, les veaux du groupe de contr?le gagnèrent en moyenne 59,4 kg ± 4,8 kg (200,0 ± 7,4 g/jour) alors que les animaux traités gagnèrent en moyenne 128,6 ± 10,5 kg (530,0 ± 13,1 g/jour).
  相似文献   
215.
SUMMARY The effects of induced parturition on clinical disease and mortality of cows were studied in 51 winter-calving, pasture-fed, dairy herds in south-western Victoria. Parturition was induced when most cows were between 27 and 35 weeks of pregnancy. Control groups were selected from herdmates that were not induced to calve. The incidence of retained placenta was much greater among induced cows of all ages. The proportion of cows affected by any clinical disease other than retained placenta, and the incidence of mortality were much greater after induction among cows aged over 6 years but not among cows aged 3 to 6 years.  相似文献   
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动物胚胎移植首次成功(Heape 1891)距今已近一百年了。在这期间,又有多种动物胚胎移植试验成功,技术也不断改进。但是,进展较大的还是近二十年间。1981年Betterid-ge总结了胚胎移植历史,列出了13种动物胚胎移植首次成功的时间和试验者[兔1891Heape;大鼠1933 Nicholas;绵羊1934Warwick等;山羊(自身重移植)1934Warwick等;小鼠1942 Fekete&Lit-tle;奶牛(流产)1949 Umbaugh;山羊1949 Warwick&Berry;奶牛1951Willett等;猪1951 Kvasnickii;奶牛  相似文献   
218.
In an attempt to establish the prevalence of cystic echinococcosis, a study was conducted in slaughter animals in three divisions of northern Turkana, Kenya. A total of 5752 goats, 588 sheep, 381 cattle and 70 camels were examined at slaughter. Echinococcus granulosus metacestodes were found in 19.4% of the cattle, 3.6% of sheep, 4.5% of goats and 61.4% of camels. The prevalence of cystic echinococcosis in cattle, sheep and goats was higher in Lokichogio than in either Kakuma or Central divisions. On the other hand, the prevalence of the disease in camels was higher in Central (84.6%) than either Lokichogio (70.6%) or Kakuma (50%). The differences in prevalence rates in different study areas are attributed to differences in environmental conditions, livestock stocking intensity and cross-border migration of livestock.  相似文献   
219.
Over the past decade, there has been an increase in the development and/or in the improvement of emerging reproductive technologies in pigs. Among emerging reproductive technologies with potential short-term application in pig production are: artificial insemination with low number of spermatozoa, cryopreservation of spermatozoa and embryos, sperm sexing, and non-surgical embryo transfer. The following review will give emphasis to recent advancements in these reproductive technologies that are starting to show possibilities of serious applications under field conditions.  相似文献   
220.
The main aim of this study was to compare the motility and functional integrity of bull spermatozoa after single and double freezing and thawing. The viability and morphological integrity of spermatozoa selected by PureSperm density gradient centrifugation after cryopreservation of bovine semen in two commercial extenders (Experiment 1) and the function of bull spermatozoa before and after a second freezing and thawing assisted by PureSperm selection (Experiment 2) were examined. On average, 35.8 +/- 12.1% of sperm loaded onto the PureSperm density gradient were recovered after centrifugation. In Experiment 1, post-thaw motility and acrosome integrity were higher for spermatozoa frozen in Tris-egg yolk extender than in AndroMed, whether the assessments were made immediately after thawing [80.4 +/- 12.7 vs 47.6 +/- 19.0% motile and 78.8 +/- 8.3 vs 50.1 +/- 19.5% normal apical ridge (NAR), p < 0.05] or after preparation on the gradient (83.3 +/- 8.6 vs 69.4 +/- 15.9% motile and 89.5 +/- 7.2 vs 69.1 +/- 11.4% NAR, p < 0.05). For semen frozen in Tris-egg yolk extender, selection on the PureSperm gradient did not influence total motility but significantly improved the proportion of acrosome-intact spermatozoa. After the gradient, both the total motility and percentage of normal acrosomes increased for spermatozoa frozen in AndroMed (Minitüb Tiefenbach, Germany). In Experiment 2, there was no difference in sperm motility after the first and second freeze-thawing (82.9 +/- 12.7 vs 68.8 +/- 18.7%). However, the proportion of acrosome-intact spermatozoa was significantly improved by selection through the PureSperm gradient, whether measured by phase contrast microscopy (78.9 +/- 9.7 vs 90.4 +/- 4.0% NAR, p < 0.05) or flow cytometry (53.4 +/- 11.7 vs 76.3 +/- 6.0% viable acrosome-intact spermatozoa, p < 0.001). The improvement in the percentage of spermatozoa with normal acrosomes was maintained after resuspension in the cooling extender and cooling to 4 degrees C (88.2 +/- 6.2) and after re-freezing and thawing (83.6 +/- 6.56% NAR). However, flow cytometric assessment of the sperm membranes revealed a decline in the percentage of viable spermatozoa with intact membranes after the second freezing and thawing compared with after gradient centrifugation (76.3 +/- 6.0% vs 46.6 +/- 6.6%, p < 0.001) to levels equivalent to those obtained after the first round of freeze-thawing (53.4 +/- 11.7% viable acrosome-intact spermatozoa). Sperm movement characteristics assessed by computer-assisted analysis were unaffected in the population selected on the PureSperm gradients but declined after cooling of the selected and extended spermatozoa to 4 degrees C. There was no further change in these kinematic measurements after the cooled spermatozoa had undergone the second round of freeze-thawing. These results demonstrate that bull semen can be frozen and thawed, followed by a second freeze-thawing cycle of a population of spermatozoa selected by PureSperm, with retained motility and functional integrity. This points to the possibility of using double frozen spermatozoa in bovine artificial insemination programmes and to the potential benefits of PureSperm density gradient centrifugation for the application of cryopreserved bull spermatozoa to other biotechnological procedures such as flow cytometric sex sorting followed by re-freezing and thawing.  相似文献   
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