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1.
低死亡率和较高的饲料利用率 ,看来是鸡抗氧化状态得到改善的结果。增高日粮维生素E的含量并应用有机硒可减少肺高压 (腹水症 )引起的死亡。  相似文献   
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Luteolytic doses of the Tham salt of PGF2 or one of its synthetic analogues cause premature regression of, the corpus luteum between the 5th and the 16th day of the oestrous cycle, inducing, 2 to 4 days after the injection, endcrine changes similar to a normal lultolysis and oestrus. After insemination at the time of this oestrus or at predefined times 72 to 96 hours after the injection, fertility is similar to that in controls. The paractical use of prostaglandins for the synchronization of oestrus in a herd of randomly cyclic animals takes account of the fact that only animals between the 5th and the 16th day respond to an injection. Various techniques are proposed, notably a double injection with an interval of 10–12 days.
Kurzfassung Luteolytische Dosen eines Tham'schen Salzes von PGF2, oder einer dessen synthetischen Analogen bringen vorzeitige Regressionen des corporis lutei zwischen dem 5ten und dem 16ten Tage hervor. Als Folge dieser Regressionen entwickeln sich innerhalb 2 bis 4 Tage nach der Einspritzung endokrine Veränderungen, die der normalen Luteolyse und Brunst ähnlich sind. Nach einer Besamung zur Zeit dieser Brunst oder zu vorherbestimmten Zeiten und zwar 72 und 92 Stunden nach der Einspritzung wird die gleiche Frunchtbarkeit wie in unbehandelten Kontrollen beobachtet. Nur ein Teil einer zyklischen Herde reagiert auf Prostaglandin, und es werden daher verschiedene Methoden der Viehwirtschaftsführung zur Überwindung dieses Problems erörtert, wie auch den Gebrauch einer Doppeleinspritzung von Prostaglandin mit einem 10 bis 12 tägigen Abstand zwischen den Behandlungen.

Resume Les doses lutéolytiques de sel Tham de PGF2 ou d'un de ses analogues synthetiques causent une reégression prématurée du corps jaunne entre le 5ème et le 16ème jour du cycle provoquant, 2 à 4 jours après l'injections, des changements endocriniens semblales à une lutéolyse normale et à un oestrus. Après l'insémination au moment de cet oestrus ou à des temps prédéfinis de 72 à 96 heures après l'injection, la fertilité est semblable à celle des animaux témoins non traités. L'utilisation pratique des prostaß-landinesd pour la synchronisation des chaleurs dans un troupoeau de femelles cyclées tient compte du fait que seules les femelles entre le 5ème et 16ème jour du cycle répondent à une injection. Différentes techniques sont proposées, notamment la double injection à 10–12 jours d'intervalle.

Riassunto Le dosi luteolitiche del sale Them PGF2 o di uno dei suoi analoghi sintetioi causano una regressione prematura del corpo giallo tra il 5o ed il 16o giorno del ciclo provooando, dopo un periodo che va dai 2 ai 4 giorni dall'iniezione, dei cambiamenti endocrini simili ad una luteolisi normale o ad un estro. Dopo l'inseminazine, nel momento di questo estro oppure in tempi predeterminati, in un periodo compreso tra 72 e 96 ore dopo l'iniezione, la fertilità è simile a quella jdegli animali di controllo non trattati. L'utilizzazione poratioa della prostaglandine per la sincronizzazione dei oalori in una mandria di femmine cicliche dimostra che le femmine rispondono all'iniezione soltanto tra il 5o ed 16o giorno del ciclo. Si propongono diverse techniche, in poarticolasre la doppia iniezione ad un intervallo di 10–12 giorni.
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Tissue samples were collected postmortem from 126 sheep at five lymphoreticular sites by different techniques. The three most successful combinations of sites and techniques were: the third eyelids, using a forceps and scissors, which provided a mean (se) of 5.32 (0.70) lymphoid follicles per 5 microm tissue section, a mandibular lymph node, using a Biopty gun, which gave 1.19 (0.26) lymphoid follicles per 5 microm tissue section, and tonsil, using a biopsy forceps, which gave 1.14 (0.27) lymphoid follicles per 5 microm tissue section. These three techniques were repeated once a month for five months on five sheep under general anaesthesia, and their clinical effects were compared with five control sheep which were restrained and anaesthetised in the same way but from which no biopsies were taken. Most lymphoid follicles (3.47 [0.58] per 5 pm tissue section) were obtained by using the third eyelid biopsy technique. There were no clinical side effects associated with the biopsy procedure. There were increases in the plasma concentration of cortisol in all the animals, suggesting that the restraint and anaesthesia were more stressful than the biopsy procedure.  相似文献   
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This paper discusses the use of resorcylic acid lactone as an anabolic agent in cattle. When given to finishing steers it increases daily gain by 10–18% and final carcass weight by 6–10 kg. When given to finishing steers in conjunction with trenbolone acetate, there is an additive response in terms of growth rate and carcass weight. The final carcass weights were 310±2.1, 319±2.0, 316±2.0 and 328±2.0 for unimplanted steers, or steers implanted with resorcylic acid lactone or trenbolone acetate or a combination of both compounds respectively. Responses in finishing steers in spring at pasture were similar to responses obtained in winter. In male calves, average liveweights at the end of a 134-day experimental period were 123, 142 and 140 kg (SE ± 5.4 kg) respectively for control calves or calves given resorcylic acid lactone or a combination of resorcylic acid lactone and trenbolone acetate. After a further 134 days grazing together these calves weighed 271, 294 and 297 kg (SE ± 7.9 kg) respectively, indicating that the extra gain was retained once the implants ceased to be effective. No significant effect on daily gain or carcass weight of heifers was obtained in our trials with resorcylic acid lactone. Results from feed efficiency trial indicated resorcylic acid lactone significantly increased feed efficiency. Therefore, resorcylic acid is an effective growth promoter in male castrate cattle.  相似文献   
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This paper analyzes rancher participation in conservation programs in the context of a social-ecological framework for adaptive rangeland decision-making. We argue that conservation programs are best understood as one of many strategies of adaptively managing rangelands in ways that sustain livelihoods and ecosystem services. The framework hypothesizes four categories of variables affecting conservation program participation: operation/operator characteristics, time horizon, social network connections, and social values. Based on a mail survey of California ranchers, multinomial logit models are used to estimate the impact of these variables on different levels of rancher involvement in conservation programs. The findings suggest that ranchers with larger amounts of land, an orientation towards the future, and who are opinion leaders with access to conservation information, are more likely to participate in conservation programs.  相似文献   
10.

Context

Anthropogenic activities readily result in the fragmentation of habitats such that species persistence increasingly depends on their ability to disperse. However, landscape features that enhance or limit individual dispersal are often poorly understood. Landscape genetics has recently provided innovative solutions to evaluate landscape resistance to dispersal.

Objectives

We studied the dispersal of the common meadow brown butterfly, Maniola jurtina, in agricultural landscapes, using a replicated study design and rigorous statistical analyses. Based on existing behavioral and life history research, we hypothesized that the meadow brown would preferentially disperse through its preferred grassy habitats (meadows and road verges) and avoid dispersing through woodlands and the agricultural matrix.

Methods

Samples were collected in 18 study landscapes of 5 × 5 km in three contrasting agricultural French regions. Using circuit theory, least cost path and transect-based methods, we analyzed the effect of the landscape on gene flow separately for each sex.

Results

Analysis of 1681 samples with 6 microsatellites loci revealed that landscape features weakly influence meadow brown butterfly gene flow. Gene flow in both sexes appeared to be weakly limited by forests and arable lands, whereas grasslands and grassy linear elements (road verges) were more likely to enhance gene flow.

Conclusion

Our results are consistent with the hypothesis of greater dispersal through landscape elements that are most similar to suitable habitat. Our spatially replicated landscape genetics study allowed us to detect subtle landscape effects on butterfly gene flow, and these findings were reinforced by consistent results across analytical methods.
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