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151.
152.
Caviomorph rodents are renowned for comparatively long gestations and producing relatively precocious offspring. The degu (Octodon degus) is one such caviomorph, originating in central Chile and providing communal pup care within wild groups. Reported are pup growth data for two populations of captive bred degus in Britain and Chile (representing wild populations), for the first time analysing pup development over the postpartum and weaning period in detail. Pups in both colonies were found to be similarly precocial at birth as assessed by open eyes and presence of full body hair. Degu pups in the British colonies put on weight at a rate of 2–3 g/day, while pups in the Chilean colonies put on weight at a rate of 1–2 g/day over the first 14 days. At birth, individual neonates weighed 5 ± 1% of maternal mass for the British sample and 6 ± 0.5% for the Chilean sample. Sexual dimorphism occurred in the weight and growth rates of pups in both samples, despite the lack of sexual dimorphism in adults of the species. Data for breeding female weight changes were also analysed, providing the first reported observations for this crucial period. Pregnant female weight gain was found to vary over the course of gestation, and post partum weight changes varied significantly between breeding females in accordance with litter size. 相似文献
153.
[目的]为了验证优良品种改良本地黄牛的效果,[方法]运用三个杂交组合在民和县用引进的良种肉牛西门塔尔、利木赞和皮尔蒙特牛改良当地黄牛。[结果]表明F1不同年龄的生长速度和体尺指标均明显于本地黄牛(P〈0.01),说明良种肉牛改良本地黄牛效果明显;在不同杂交后代的比较中,皮×黄F1各年龄段体重均高于西×黄F1、利×黄F1,杂交组合最为理想。[结论]说明不同的杂交组合具有不同的效果。 相似文献
154.
烟草中重金属镉污染及调控措施研究进展 总被引:3,自引:0,他引:3
烟草作为毒性较强的重金属镉的富集植物,使得人们可能在主动或被动吸烟过程中吸收重金属镉,对健康造成危害。为了增强人们对镉金属的认识,提高卷烟的吸食安全,综述了镉对烟叶品质的影响及其在卷烟烟气与烟株内部迁移规律和影响因素,以及现有的对烟草中重金属镉的调控措施,从卷烟原料调控着手,以期为寻找有效的降低卷烟中镉含量的措施提供事实和理论依据。 相似文献
155.
156.
E.E. RUFINO‐PALOMARES F.J. REYES‐ZURITA L. GARCÍA‐SALGUERO J. PERAGÓN M. DE LA HIGUERA J.A. LUPIÁÑEZ 《Aquaculture Nutrition》2012,18(2):138-151
Maslinic acid (MA) is a natural triterpene that can be used as an additive in the diet of trout. We investigated the effects of feeding with MA and a fixed ration (10 g kg?1 body weight) with respect to growth, protein‐turnover rates and nucleic‐acid concentration in the liver of gilthead sea bream grown under fish‐farm conditions. Five groups of 12 g of a mean body mass were fed for 210 days with diets containing 0 (control), 0.05 and 0.1 g of MA per kg of diet. Two groups were fed ad libitum (control AL and MA100AL), and three with a fixed ration (control R, MA50R and MA100R). At the end of the experiment, higher body weights, liver weight, feed‐efficiency and PER were found in MA100AL and MA100R fish. Fractional and absolute protein‐synthesis rates in liver of MA100R fish were higher than in the control, resulting in a higher absolute protein‐accumulation rate and tissue growth. Total DNA content in MA100AL and MA100R was higher than in control. Studies of light and electron microscopy corroborated these results. These findings indicate that MA added to the diet can stimulate growth, hepatic protein‐turnover rates and tissue hyperplasia in gilthead sea bream. 相似文献
157.
本试验测定了舍饲条件下的215只湖羊和60只湖杜湖[湖羊♂×(杜泊羊♂×湖羊♀)♀]杂交羔羊0~12月龄的体重,采用Gompertz模型和Logistic模型拟合了湖羊和湖杜湖杂交羔羊0~12月龄生长过程,并分析比较了生长参数及模型估计值,进而评价湖杜湖的杂交优势。结果表明,2种模型的拟合度(R2)均在0.96以上,拟合效果好,其中Gompertz模型拟合两个种群效果好于Logistic模型;湖羊公、母羔拐点月龄分别为2.55和1.73个月,拐点体重分别为17.00和13.14 kg;湖杜湖公、母羔拐点月龄均早于湖羊,公、母羔拐点体重分别相差0.74和2.66 kg,公、母羔累积生长均极显著高于湖羊(P<0.01)。结果说明湖杜湖早期生长强于湖羊,湖杜湖杂交效果显著。 相似文献
158.
本研究从血液生理、生化指标水平探讨有角和无角牦牛群体的体况和代谢差异,为无角牦牛新品种的选育提供理论依据。试验检测了有角、无角牦牛群体的30项血液生理与生化指标,并用独立样本t检验对两个群体测得的各项指标进行了比较分析。结果表明,两群体间有11项指标差异极显著(P<0.01),5项指标差异显著(P<0.05),14项指标差异不显著(P>0.05)。从测定的数据初步判定,有角与无角牦牛群体在高原低氧适应性、肝脏代谢、肾脏代谢及骨质形成方面存在一定差异,无角牦牛比有角牦牛更适应高原低氧的环境。本试验结果可为牦牛品种资源的合理保护和利用以及新品种的选育提供科学依据。 相似文献
159.
A comparison between cutting and animal grazing for dry‐matter yield,quality and tiller density of perennial ryegrass cultivars 下载免费PDF全文
Perennial ryegrass (Lolium perenne L.) evaluation trials are often conducted under simulated grazing to identify the most productive cultivars. It is unclear whether simulated grazing identifies the most productive cultivar for animal‐grazed swards. Ten cultivars were established as plots and managed concurrently under simulated grazing (SG), animal grazing (AG) and conservation (CON). The experiment lasted 3 years with dry‐matter (DM) off‐take, digestibility, tiller density and ground‐cover score recorded in all years. A good relationship existed between DM off‐take under SG and CON (R2 = 0·73). The relationship between SG and AG was strongest in year 2 and 3 (R2 = 0·53 and 0·55 respectively). High DM production was observed in SG swards in year 1; this was weakly related to the DM production of the AG sward. Across the 3 years, the CON treatment had higher yields than either of the other two treatments and was poorly correlated to DM yield under AG, confirming that cultivars should be evaluated under a similar defoliation frequency to their intended use. Tiller density declined quickest under CON and slowest under AG. Some reranking of cultivars occurred between defoliation managements. The results show that simulated grazing is a useful indicator of DM yield performance of animal‐grazed swards. 相似文献
160.
This case report describes neurological signs associated with a pyogranulomatous lesion within the sacral vertebral canal of a horse. The clinical findings included urinary overflow incontinence and reduced anal, perianal and tail tone. The horse failed to respond to medical management and a guarded prognosis for return to athletic performance initiated the decision for euthanasia. 相似文献