Long-term stochastic simulation of mountain beef cattle herds under diverse management strategies

A stochastic simulation model was used to assess the effects of diverse management strategies on beef herds under mountain conditions in the Spanish Pyrenees. Animals grazed on different seasonal resources (valley meadows, forest pastures and mountain pastures) and were fed with forages and concentrates during winter. The simulated management strategies were winter calving (WC, weaning at 180 days), autumn calving (AC, weaning at 160 days), 8-month calving (8MC, weaning at 180 days), and two calvings in 3 years, with weaning taking place at either 170 days of age (2C3Y) or at 9 months (2C3Y9 M). Each strategy was tested for two types of production systems: (i) cow-calf farms that market calves just after weaning; and (ii) cow-calf/finishing farms that fatten the animals by means of an intensive feeding system until achieving a suitable weight for slaughter. A herd of 100 cows was simulated over 15 years, but only data obtained after reaching the steady state (year 6) was used in the analysis. The strategies were evaluated by considering reproductive, productive and economic performance. The percentages of pregnant cows at the end of the mating season were highest for 8MC, 2C3Y and 2C3Y9M (between 92% and 94%). The percentage was intermediate for AC (88%) and lowest for WC (78%), which also showed greater variability between years. The two strategies that extensified management (2C3Y, 2C3Y9M) produced, as expected, a lower number of calves weaned per year (59 and 60), whereas this figure was the highest for 8MC (90). Although AC and 8MC resulted in higher productive performances, the increased labour requirements and winter feeding costs resulted in low economic margins for these strategies, which also meant poorer utilization of natural resources. In economic terms, WC was the best strategy for cow-calf/finishing farms, whereas 2C3Y was the worst of the two types of production systems, although it resulted in the most intense utilization of grazing resources. The long lactating period of 2C3Y9M did not affect the reproductive performance of cows, so this strategy yielded the highest economic margin at weaning. The extensification strategies (2C3Y and 2C3Y9M) were less sensitive to changes in the price of feedstuffs. The information obtained from the simulation of the different strategies is useful for evaluating the possible trade-offs between production, economics, use of natural resources and labour requirements.     

LTSER platforms as a place-based transdisciplinary research infrastructure: learning landscape approach through evaluation

Landscape Ecology - Place-based transdisciplinary research involves multiple academic disciplines and non-academic actors. Long-Term Socio-Ecological Research (LTSER) platform is one concept with ~...     

Evaluation of the resistance of Coffea canephora to Oligonychus ilicis (Acari: Tetranychidae) and the preimaginal conditioning effect on resistance using a biological life table

Oligonychus ilicis (McGregor) (Acari: Tetranychidae), is one of the most important mite pests found in coffee plants. One way to reduce intensive pest attacks is management via resistant plants. The purpose of this study was to evaluate the resistance of 14 C. canephora genotypes to O. ilicis by antixenosis and antibiosis mechanisms and to determine the preimaginal conditioning effect on resistant genotypes using O. ilicis reared on C. canephora. Resistance by antixenosis was not found; however, nine genotypes showed resistance to O. ilicis via an antibiosis mechanism. Two of these resistant genotypes showed a more persistent resistance than the O. ilicis reared on C. canephora, which indicated that a previous host can affect the selection of a genotype by O. ilicis. The study may provide a model to evaluate the preimaginal conditioning effect on plant resistance, which can be useful for plant breeders.     

Biogenic Amines and the Antioxidant Capacity of Juice and Wine from Brazilian Hybrid Grapevines

Plant Foods for Human Nutrition - Some biogenic amines (BAs) are used as quality markers in grape-derived products. The prolife of 9 BAs was determined in juices and wines elaborated from hybrid...     

Genetic transformation of Citrus sinensis cv. Hamlin with hrpN gene from Erwinia amylovora and evaluation of the transgenic lines for resistance to citrus canker

Transgenic Citrus sinensis (L.) Osb. cv. Hamlin plants expressing the hrpN gene were obtained by Agrobacterium tumefaciens (Smith and Towns) Conn-mediated transformation. hrpN encodes a harpin protein, which elicits the hypersensitive response and systemic acquired resistance in plants. The gene construct consisted of gst1, a pathogen-inducible promoter, a signal peptide for protein secretion to the apoplast, the selection genes nptII or aacC1 and the Nos terminator. The function of gst1 in citrus was evaluated in transgenic C. sinensis cv. Valencia harboring the reporter gene uidA (gus) driven by this promoter. Histochemical analysis for gus revealed that gst1 is activated in citrus leaves by both wounding and inoculation with Xanthomonas axonopodis Starr and Garces pv. citri (Hasse) Vauterin et al. Genetic transformation was confirmed by Southern blot hybridization in eight cv. Hamlin acclimatized plants. RT-PCR confirmed hrpN gene expression in seven cv. Hamlin transgenic lines before pathogen inoculation. Some hrpN transgenic lines showed severe leaf curling and abnormal growth. Six hrpN transgenic lines were propagated and evaluated for susceptibility to X. axonopodis pv. citri. RT-PCR confirmed gene expression in all six hrpN transgenic lines after pathogen inoculation. Several of the hrpN transgenic lines showed reduction in susceptibility to citrus canker as compared with non-transgenic plants. One hrpN transgenic line exhibited normal vegetative development and displayed very high resistance to the pathogen, estimated as up to 79% reduction in disease severity. This is the first report of genetic transformation of citrus using a pathogen-inducible promoter and the hrpN gene. Further evaluations of the transgenic plants under field conditions are planned. Nevertheless, the evidence to date suggests that the hrpN gene reduces the susceptibility of citrus plants to the canker disease.     

Does the presence of microalgae influence fish larvae prey capture?

The green water technique has been widely shown to improve fish larvae growth, survival and feed ingestion. Therefore, fish larvae (Sparus aurata L. and Solea senegalensis Kaup) feeding behaviour was studied through gut content analysis, when using different species of microalgae, as the ‘green water’ technique. Six treatments were used: Stain – food green stain; Tetra – microalgae Tetraselmis chuii; Iso – microalgae Isochrysis galbana; Tetra Sup –T. chuii supernatant (obtained from centrifugation); Phyto – a microalgae paste, Nannochloropsis oculata, (Phytobloom^®); and C water – clear water, as control. At 9, 16 and 23 days after hatching (DAH) for S. aurata, and 4, 9 and 14 DAH for S. senegalensis, 40 unfed fish larvae were transferred to 3 L experimental tanks, filled with the different ‘green water’ technique. Fish larvae were sampled 2 h after being fed with live prey, anaesthetized and fixed in buffered formaldehyde for posterior gut content determination. Feeding was evaluated by the feeding rate, percentage of larvae with prey items in the digestive tract and feeding intensity, number of prey in each larva digestive tract. Fish larvae feeding ability was influenced by the interaction between light conditions and substances provided by the presence of microalgae during fish larvae development. Sparus aurata was more dependent on microalgae addition than S. senegalensis larvae, which may be related to the type of prey, larval behaviour, ontogeny and physiology. The presence of microalgae influenced the selection of larger prey (Artemia over rotifers) by S. aurata aged 23 DAH.     

Collection of marine invertebrates for the aquarium trade in European waters: is anyone surveying?

• 1. Recently, the snails Hinia reticulatus, Cyclope neritea and Cerithium rupestre and the hermit crabs Diogenes pugilator and Clibanarius erythropus from warm European coastal waters have started to be commercially collected and traded.
• 2. The average number (± standard deviation) of specimens captured per hour, by collectors were 475±237 for H. reticulatus, 363±112 for C. neritea, 384±173 for C. rupestre, 302±121 for D. pugilator and 210±54 for C. erythropus.
• 3. All species survived well during transportation, were popular among aquarium hobbyists and attained high retail values, ranging from €0.90 to €4.00 per specimen.
• 4. The collection and trade of these novel commercial species can either become a sole economic activity or an additional one for traditional fishermen and aquaculturists.
• 5. Although no destructive collection techniques are employed, the lack of population biology studies and legislation regulating the capture of these species is a major problem in ensuring the sustainable use of these highly valuable marine resources.
• 6. These species are currently mainly collected from natural parks areas protected by Portuguese and European Union designations.

Copyright © 2007 John Wiley & Sons, Ltd.