Genetic and environmental influences on size of first litter in sheep, estimated by the REML method

Fixed effects of age at first litter and of season of lambing as well as variance components for additive genetic, flock × year and sire of litter effects on size of first litter were estimated for an animal model by a derivative-free REML procedure. Data of the four Swiss sheep breeds White Alpine (WAS), Brown-headed Meat (BFS), Black-Brown Mountain (SBS) and Valais Black Nose (SN) were available. Number of first litters used were 21 384, 21 607, 15 013, 12 394 and 18 110 the WAS (two data sets, WAS1, WAS2), BFS, SBS and SN, respectively. Litter size of ewes lambing the first time at 2 years of age was 0.27, 0.31, 0.41, 0.46 and 0.26 lambs larger than of ewes lambing the first time at 1 year of age. The largest increase occurred for the two breeds (BFS, SBS) with the lowest average age at first litter. The largest difference between any two lambing seasons within breed were 0.16, 0.16, 0.29, 0.22 and 0.07 lambs. Estimates of additive genetic variance of size of first litter were between 0.0269 (SN) and 0.0765 (SBS). Heritability estimates for this trait were 0.171, 0.156, 0.114, 0.225 and 0.122 for WAS1, WAS2, BFS, SBS and SN, respectively. A large flock × year component (relative to phenotypic variance) of 0.148 was found for SN, compared with estimates between 0.042 and 0.067 for the other breeds. A sire of litter component (relative to phenotypic variance) of 0.066 was found for SN, compared with estimates between 0.016 and 0.039 for the other breeds. It can be concluded that all nongenetic effects investigated should be taken into account for the estimation of additive genetic variance and breeding values for size of first litter, and that considerable variation in size of genetic and nongenetic effects exists in the sheep breeds under consideration.     

Blood levels of hormones and metabolites, erythrocytes and leukocytes and respiration and pulse rate of heifers after alpage

High-altitude grazing, at or above the timberline in summer months continues to be important in alpine regions of Europe, where about 80% of young stock spend much of the three summer months on these pastures. Apart from direct utilization of these resources and saving of feed in the home farms, alped cattle are said to have greater longevity and better growth, i.e. they display compensatory growth. K& uuml ; nzi et al. (1988), S uttner (1980) and R uhland (1983) reported that heifers which spent one or two summers on alpine pastures, have, as cows in intra-herd comparisons, about one lactation more than homegrown heifers. Compensatory growth after alpage was reported by these authors, by B ianca (1977), W eilenmann -B ossart (1988) and other authors. The effects of alpine sojourn on physiological and biochemical traits were investigated by B ianca and E spinosa (1975), B ossart et al. (loc. cit.), K rippl et al. (1961) and S uttner (1980). This investigation concerns the comparative effects of alpine pasture and farm feeding on subsequent physiological and biochemical traits.     

High performance liquid chromatography determination of ergosterolas a measure of ectomycorrhiza infection in Scots pine

A technique for determining the ergosterol content in mycorrhizal pine roots using HPLC was developed. Pure cultures of different my corrhizal fungi contained very similar and constant amounts of ergosterol, and calculations of fungal biomass in mycorrhizal roots based on ergosterol readings agreed well with results using other methods. The extraction and sample purification were simple and reliable. Consequently, the technique is considered practical wherever accurate estimates of the intensity of mycorrhizal infection are required.     

Tracking leaf area index and coefficient of light extinction over the harvesting cycle of black wattle

The amount of photosynthetic radiation intercepted by a crop is a function of the incident solar radiation on the plants, the leaf area index (L _AI), and the light extinction coefficient (k). We quantified L _AI and k in stands of black wattle (Acacia mearnsii De Wild.) over a 7-year growth cycle at two locations in the state of Rio Grande do Sul, Brazil. Our study was conducted in commercial stands in agroecological regions with high densities of black wattle plantations. L _AI was calculated as the ratio between the leaf area of a tree and its planting space, and k was derived from Beer’s law. L _AI depends on the planting site and stand age. Between the two sites, the L _AI was similar over time, the amount of variation differed. Values of k depended only on stand age, with the highest average observed for stands up to 5 years old. The trend of k during the plantation cycle was inversely proportional to L _AI and was correlated with L _AI, leaf area, leaf dry mass, canopy volume, height, branches dry mass, total dry mass, and crown diameter.     

Incidence of dieback disease following fungal inoculations of sexually and asexually propagated shisham (Dalbergia sissoo)

Shisham (Dalbergia sissoo) is an important multipurpose tree with great economic importance, but this tree has been devastated by dieback disease. Seedlings and asexually propagated (cuttings) plants were artificially inoculated with four fungi (Fusarium solani, Botryodiplodia theobromae, Curvularia lunata and Ganoderma lucidum) to evaluate the potential role of these fungi in shisham dieback disease. Results at 2 years revealed that highest disease was caused by inoculation of F. solani (31.39%), followed by B. theobromae (19.042%) and C. lunata (12.22%), but no dieback disease was caused by G. lucidum. During both years, seedlings exhibited greater susceptibility to disease (17.24%) compared to cuttings (7.83%). In particular, F. solani caused more disease in seedlings (46.18%) compared to cuttings (16.61%). With the F. solani inoculations, maximum disease rate was observed at 8 weeks post‐inoculation both in seedlings (77%) and in cuttings (31%), but the maximum disease increase was observed at 4–5 weeks post‐inoculation. Analysis of variance showed significant differences among the different fungi and also between seedlings and cuttings. F. solani can be considered as a major fungal pathogen contributing to dieback disease of shisham, and asexual propagation can reduce the severity of dieback.     

国外黑荆树资源利用状况及我国发展的前景

黑荆树是一种周期短、用途广、效益高的好树种.它原产于澳大利亚,现已在南美和亚洲广泛种植和利用.世界现有黑荆树人工林40多万公顷.黑荆树栲胶年产量11万多吨,占总产量的20%.本文着重介绍了南非和巴西的经验且结合国情认为我们应借鉴国外经验改变传统经营方式走发展工业人工林的道路.     

印度林业发展道路及经验

印度是个千年古国,在发展林业方面有着独到之处。几百年来印度林业经历了森林破坏阶段、巩固和保护阶段、开发和扩大阶段、集约经营阶段和生态林业阶段。作者对于印度发展社会林业、森林发展公司,以及缓解薪炭材危机所采取的对策作了重点介绍,同时还指出了存在的问题和采取的措施。     

山区建设必须以林业为基础

我国2/3为山地,《国家十四个重要领域技术政策要点》没有把山区建设作为重点加以研究。目前全世界对山区建设也极少开展理论研究。恩格斯《自然辩证法》所告诫的错误,仍在当今世界的各地重演。不重视基础研究,没有基础理论做指导,在我们社会主义中国的山区建设中也难免还要犯严重错误。