Determination of PCDDs and PCDFs in different animal feed ingredients

As result of a study to control feedstuff, analyses were carried out to evaluate the contamination caused by PCDDs and PCDFs in different animal feed ingredients. Thirty two samples were selected, including ingredients of animal and mineral origin. For samples of mineral origin, some additives widely employed as binder and anticaking agents, such as bentonite, damoline, kaolin, magnesite, sepiolite and zeolite were selected. And, for ingredients of animal origin, samples of hemoglobin, animal fat, fish oil, fish meal and meat and bone meal were analyzed. The levels ranged from 0.52 to 9.08 pg WHO-TEQ/g fat for samples of animal origin, and from 0.05 to 460.59 pg WHO-TEQ/g for samples of mineral origin. The higher concentrations were observed for the kaolin samples that presented high levels of dioxin contamination.     

Comprehensive study on dioxin contents in binder and anti-caking agent feed additives

Polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) were determined in some additives widely employed as binder and anti-caking agents in feedstuffs, such as kaolin, bentonite, zeolite, etc. with an special attention on sepiolite samples. Owing to their physico-chemical properties, the little information of these materials reported in the literature, the variability of PCDDs/PCDFs found in a preliminary evaluation and the absence of reference materials highlighted further research needed. Therefore, an extensive study on the analytical procedures based on the classical methods was performed with sepiolite samples. The study includes evaluation of reproducibility and repeatibility. To this end, a series of intra-day and nine inter-day analysis were made. The methodolgy was also assessed against the sample size and series of 12.5, 25, 37.5 and 50 g were analyzed. In all cases, the results confirmed good correlation with the parameters evaluated.     

Pesticide residues in products of plant origin in the European Union

The results of a co-ordinated monitoring programme for pesticide residues in the European Union and Norway carried out in 1996 and 1997 are presented. The aim of this programme is to work towards a system, which makes it possible to estimate actual dietary pesticide intake for the population of the European Union. Based on a statistically dérived sampling plan and within the limited number of pesticides/commodities analysed, the most critical pesticides (benomyl group and dithiocarbamates) and commodities (mandarine and lettuce) were identified. In case of detected non-compliances, repeated sampling and, if necessary, enforcement actions are to be taken by national authorities. The programme will be continued in the next years.     

Selecting suitable sites for animal waste application using a raster GIS

Rapid growth of intensive animal industries in southeast Queensland, Australia, has led to large volumes of animal waste production, which posses serious environmental problems in the Murray Darling Basin (MDB). This study presents a method of selecting sites for the safe application of animal waste as fertiliser to agricultural land. A site suitability map for the Westbrook subcatchment within the MDB was created using a geographic information system (GIS)-based weighted linear combination (WLC) model. The factors affecting the suitability of a site for animal waste application were selected, and digital data sets derived from up to 1:50,000 scale maps were acquired. After initial preprocessing, digital data sets were clipped to the size of the delineated subcatchment boundary producing input factors. These input factors were weighted using the analytical hierarchy process (AHP) that employed an objectives-oriented comparison (OOC) technique to formulate the pairwise comparison matrix. The OOC technique, which is capable of deriving factor weight independently, formulated the weight derivation process by making it more logical and systematic. The factor attributes were classified into multiple classes and weighted using the AHP. The effects of the number of input factors and factor weighting on the areal extent and the degree of site suitability were examined. Due to the presence of large nonagricultural and residential areas in the subcatchment, only 16% of the area was found suitable for animal waste application. The areal extent resulting from this site suitability assessment was found to be dependent on the areal constraints imposed on each input factor, while the degree of suitability was principally a function of the weight distribution between the factors.     

我国规模化畜禽养殖业存在的环境问题与防治对策

近年来，由于我国畜禽养殖业的养殖规模、养殖方式和分布区域发生了巨大的变化，它所带来的环境污染问题总体呈现出总量增加、程度加剧和范围扩大的趋势，归纳了我国规模化畜禽养殖业环境污染的特点，从生产、技术、政策和管理上分析了影响我国畜禽养殖业环境污染的主要因素，并提出了污染防治的对策建议，即借鉴发达国家畜禽养殖业的环境管理经验，以减量化、资源化、无害化及实用、廉价为原则，合理规划、防治结合，努力探索一条具有中国特色的规模化畜禽养殖污染防治道路。     

Variations in land requirements for meat production

Production of meat requires substantial amounts of feed grains which in turn require vast amounts of land. Future population growth and increase in consumption will raise the demand for meat and with it the land required for meat production. This paper analyses the various factors that affect land requirements for meat production. Meat production by Dutch broilers, pigs and beef cattle on their current feeds are compared and options for change are evaluated with respect to their nutritional needs. Differences in land requirements of a factor of 3 were found between different agricultural production systems and feeds as well as between types of livestock. It is shown that broilers have the lowest land requirement while beef cattle have the highest. The variation in feed crop yields between agricultural systems is discussed. It is concluded that due to the large variation within the system there is potential for reduction in the land requirements for meat production.     

大伙房水库上游禽畜业污染现状及其防治对策

为了保护大伙房水库 ,控制水库上游禽畜养殖业污染 ,对禽畜养殖业污染现状进行了调查 ,估算了禽畜粪尿的流失量。结果表明 ,一头猪日排泄粪尿量约是人排粪尿的 5倍。水库上游禽畜养殖业污染负荷已超过水库上游生活污水的污染负荷 ,成为了水库上游地区主要的有机物污染源。对此 ,提出了控制禽畜业污染的对策和建议。     

Adaptive strategies of territory formation

How do territorial animals gain ownership of an area? Early modelling has considered the evolution of fighting when the winner can claim the right to the resource. Recently, alternative hypotheses have been offered where repeated interactions lead to division of space through 'nagging' instead of one decisive fight. However, these models assume that animals avoid areas in which they have taken part in aggressive interactions, but do not consider whether avoidance itself is adaptive. We aim to bridge this gap between mechanistic and adaptive explanations, by presenting a game-theory model where individuals choose whether to return to an area after a fight with a specific outcome (win, loss, draw). We show that avoidance of areas where fights have occurred can be adaptive, but only if benefits of access to the area are low compared to costs of fighting. Otherwise, one individual (typically the winner) responds by returning to the area, and the other (loser) avoids it. In such cases, space is gained by winning fights. We also consider the role of conventions. If responses to fights were purely conventional, paradoxical strategies where losers of fights gain ownership would be equally logical as common-sense ones where winners claim ownership. Paradoxical solutions can be stable but only when there is little difference in fighting ability between the competitors, when individuals adhere very strictly to a behavioural rule without much random variation, and when the population in its ancient state used a paradoxical strategy.     

Hidden Markov models for circular and linear-circular time series

We introduce a new class of circular time series based on hidden Markov models. These are compared with existing models, their properties are outlined and issues relating to parameter estimation are discussed. The new models conveniently describe multi-modal circular time series as dependent mixtures of circular distributions. Two examples from biology and meteorology are used to illustrate the theory. Finally, we introduce a hidden Markov model for bivariate linear-circular time series and use it to describe larval movement of the fly Drosophila. Received: September 2003 / Revised: March 2004     

Ethics and farm animal welfare

In this paper the authors argue that ethical considerations are relevant for evaluating animal production systems and that in consequence agrologists should seriously consider the arguments of animal welfare supporters. Furthermore, the authors point out the ethical basis for some (though not all) of the conclusions proposed by supporters of animal welfare. In consequence it is necessary to determine the nature of animal welfare and methods of evaluating the welfare of animals and to recognize when production systems fail to satisfy the needs of animals.