农艺措施对脱毒甘薯原原种的产量和生育进程的影响

针对脱毒甘薯原原种特殊的生长环境,研究了氮肥、栽培密度２因素与脱毒甘薯原原种产量及生长状况的关系。结果表明,每公顷栽插鲁薯７号快繁试管苗６．７５万株,施纯氮１５ｋｇ,产量可达８６９２ｋｇ／ｈｍ２,最大叶面积到达时间较同品种未脱毒甘薯提前５～１０ｄ;针对脱毒甘薯营养生长期长,块根膨大期短的特点,提出了控制氮肥的用量,适当增加栽插密度以提高甘薯单产的栽培措施。     

Influences of breeder age and fasting after hatching on the performance of broilers

In this trial, we assessed the effects of 2 different ages of breeders and of 2 periods of fasting posthatching on the performance of broilers up to 42 d of age. Male broilers from breeders of different ages (30 and 60 wk) were subjected to an experimental design with 4 treatments: 1) T1, chicks not subjected to fasting, from 30-wk-old breeders; 2) T2, chicks not subjected to fasting, from 60-wk-old breeders; 3) T3, chicks subjected to a 12-h fast, from 30-wk-old breeders; and 4) T4, chicks subjected to a 12-h fast, from 60-wk-old breeders. At the end of the trial, feed intake was greater for the chicks from older breeders. Fasting had a negative influence on feed intake in the period from 0 to 10 d of age. The birds from older breeders had a greater BW gain from 21 to 35 d of age when they were not subjected to a fasting period, but when birds were subjected to a fasting period, no differences between broiler breeder ages were observed on BW gain. Fasting did not exert a significant effect on the BW of the birds. Feed conversion was not influenced by the age of the breeders or by fasting.     

肉用种鸡强制换羽期的内分泌学变化

应用放射免疫分析法，测定７３－７６周龄红宝肉用种鸡断换羽期外周血清中甲状腺素，同醇，雌二醇和促黄体素的分泌水平。结果；Ｅ２和ＬＨ分泌水平在断料的第７，１３，２１，２５ｄ分别降低８．５％，２４．１％，２５．８％，２２．４％和５．７，１０．６％，９．９％，１８．４％，证实Ｅ２和ＬＨ分泌水平的降低与卵巢中卵泡的退化相。     

Selection strategies to reduce invasive potential in introduced plants

Summary The crop domestication process is examined from plant collection to product release for various junctures at which deliberate breeding, selection, and crop transformation may occur to prevent invasive potential. Four primary juncture opportunities for research on techniques and development of selection procedures for non-invasiveness include: The Plant Exploration Phase, Initial Trial Phase, Fast-Tracking Phase, Selection and Improvement Phase. Avoiding the collection of germplasm that appears weedy during plant exploration is an obvious, yet cost-effective way to reduce invasiveness in a selection program. During initial trials, comparing genotypic differences in traits related to invasiveness should allow plant breeders to identify cultivars that pose the least risk before undertaking comprehensive field trials. Genotypes with high commercial value, considered candidates for “fast-tracking”, should only advance quickly to product release if they exhibit a minimum level of invasive risk, i.e., species with low dispersal capacity and that have little potential to impact ecosystems. Fast-growing taxa, those with high seed production, ones likely to be rapidly dispersed by wind, animals, water or people, and others that can significantly alter nutrient or light levels are examples of species that should not be “fast-tracked”. Field trials that have typically been used to evaluate performance of genotypes across a broad range of cultivated environmental conditions need to be expanded to adequately evaluate invasive potential during the selection and improvement phase. Testing in environments that mimic conditions where introductions could naturalize is crucial, as are evaluations of competition with indigenous species. The time and resource investment needed to conduct adequate trials at this stage is potentially very high; more research is needed to ensure the trials conducted are targeting important information gaps for decision-making. Additional research is also needed to develop modeling approaches that effectively forecast long-term dynamics of introductions and to assist in developing field testing priorities. Minimizing invasive potential could significantly reduce introductions that cause inadvertent damage to landscapes and ecosystems. The strategy proposed here will require further development, especially in the context of understanding and assessing risks of pre- and post-release strategies for minimizing damage from invasive species. Scientific Paper No. 051210156 of the Department of Horticultural Science.     

肉种鸡养殖管理技术要点

相较于其他家禽养殖,肉种鸡养殖有着更严格的技术要求,要求养殖系统性、精细化。部分养殖户在发展肉种鸡养殖过程中不注重做好养殖管理工作,普遍存在技术空缺,很容易造成各种传染性疾病发生,影响肉种鸡正常生长,最终影响养殖户经济效益。该文在总结以往养殖经验的基础上,探讨肉种鸡饲养管理技术要点。     

Relationships of Body Weight,Feathering, and Footpad Condition with Reproductive and Carcass Morphology of End-of-Season Commercial Broiler Breeder Hens

Reproductive efficiency of broiler breeder hens declines with age. Whereas careful feed management can maximize BW uniformity at housing, there is variability in how rate of lay and flock behavioral dynamics will interact with subsequent growth during the breeder phase. This study characterized differences in carcass and reproductive morphology in end-of-cycle commercial broiler breeder hens based on BW, feather coverage, and footpad condition, and we discuss the potential implications of the findings. At 62 wk of age, 537 hens were studied from an original flock of 3,800. Birds were sorted into subgroups based on BW, feather score, footpad score, and whether they were in laying condition when dissected. The average flock BW was 3.56 kg, with means of 2.86, 3.56, and 4.20 kg for the low (LOW), standard (STD), and high (HIGH) BW groups, respectively. A higher proportion of birds from the STD (85%) and HIGH (81%) groups still had a fully formed reproductive tract compared with birds of the LOW (59%) group. The LOW birds in laying condition had a smaller ovary than the STD or HIGH birds. The ovary condition of birds in laying condition was not related to feather coverage. As feather coverage improved, final hen BW increased, demonstrating a potential role of feather coverage in growth efficiency or of BW in level of mating activity. Birds that received a feather score of 5 (complete back feather coverage) and had a normal reproductive tract made up 14.7% of this flock. It is likely that many of these birds were mating very infrequently or possibly not mating, which has implications for maintenance of flock fertility. Some may also have been returning from a molt. Footpad condition was not related to body size. External traits such as BW, feather score, and footpad score can provide insight into flock reproductive condition and male:female interaction.