Preference and Willingness of Consumers to Pay for Value-added Poultry Products in Niger Delta Region of Nigeria

There has been a steady growth in demand for convenience and ready-cooked food has influenced the interest of poultry processors in developing value-added chicken products that meet consumers' demand/choice. A conjoint analysis was done in this study on the survey of 975 chicken consumers in the Niger Delta Region of Nigeria, between March and September, 2014 to valuate consumers, preferences and willingness to pay (WTP) for various chicken attributed parts, production method, processing method, storage method, the presence of flavor and cooking method. The estimates of consumers, WTP premium prices for various mixtures of value-added characteristics were ascertained. The consumers preferred chicken products refrigerated, from chicken produced under free-range management, chicken breast, chicken product that was addictive and flavor free, which could be oven-heated or pan heated. One half of the entire respondents were willing to pay about 25% more for value-added chicken product over the price for conventional products. On the whole, a premium for value-added chicken products was more likely to be paid for by young consumers, consumers who patronized farmers' markets and preferred free-range or organic chicken products. WTP by consumers was negatively affected by price of products. The poultry industry could utilize combined knowledge of consumers' WTP for value-added chicken product price as a guide of develop innovative value-added chicken products.     

不同寄主来源的葡萄霜霉病菌致病力测定及孢子囊大小比较

对采自我国不同地区、不同主栽葡萄品种‘红地球’、‘巨峰’及‘赤霞珠’上的12份葡萄霜霉病菌的致病力及孢子囊大小进行了比较和分析,结果表明:采自不同葡萄品种的病原菌对感病葡萄品种‘奥迪亚无核’叶片的致病力具有明显差异,其中‘巨峰’及‘红地球’来源的病原菌致病性较强,明显大于‘赤霞珠’来源的病原菌致病力;采自不同葡萄品种的霜霉病菌孢子囊大小存在一定的差异,‘赤霞珠’来源的病原菌孢子囊明显大于‘巨峰’及‘红地球’来源的霜霉病菌孢子囊。上述结果表明,采自不同寄主的葡萄霜霉病菌的致病力及孢子囊大小均存在一定程度的分化。     

油茶象甲成虫对油茶寄主选择性研究

为研究油茶象甲对油茶寄主的选择性趋性,为中国油茶抗虫品种选育提供基础数据。应用野外调查和室内测定相结合的方法,室内测定又分为强迫性和选择性取食、产卵以及嗅觉反应测定的方法,测定油茶象甲成虫对不同油茶树种、品系的取食和产卵选择性。结果发现：油茶象甲对油茶2个树种、3个品系均能造成危害,导致采果前落果的主要原因是由于该虫为害所致;6月份,该虫对其他1个树种、3个品系的取食、产卵趋性均大于广宁红花油茶;该虫在油茶叶片上不产卵,当果皮厚度大于其能蛀入最大值时不产卵;雌成虫出土初期对油茶嫩芽的趋性大于果实和成叶,交配产卵期对油茶果实的趋性大于嫩芽和成叶。     

Dietary habits of grazers influence their suitability as biological controls of fouling macroalgae in ex situ mariculture

The dietary habits of the sea urchin Salmacis sphaeroides and the gastropod Trochus maculatus in ex situ mariculture were examined. Fouling algal assemblages on terracotta tiles were exposed to the grazers and compared. Except for Day 0, the assemblages on Days 2, 13 and 27 differed significantly across treatments. S. sphaeroides rapidly consumed most algae, leaving an assemblage dominated by turf algae and bare tile. T. maculatus primarily fed on green filamentous algae, resulting in an even distribution of other algal functional groups, while control tiles were dominated by green filamentous algae. Using three representative fouling algae species (Bryopsis corymbosa, Hypnea spinella and Lobophora variegata), the consumption rates of both grazers and dietary preferences of S. sphaeroides were examined through a single‐diet and a choice experiment respectively. The single‐diet experiment revealed differential algal consumption rates for S. sphaeroides (H. spinella = B. corymbosa > L. variegata) and T. maculatus (B. corymbosa > H. spinella = L. variegata). The choice experiment showed that S. sphaeroides preferred H. spinella over the other two species. These experiments highlighted the importance of understanding the dietary habits of grazers as this has direct implications on their effectiveness as biological controls of fouling macroalgae in mariculture.     

Habitat management and patterns of predation of Northern Lapwings on wet grasslands: The influence of linear habitat structures at different spatial scales

In managed landscapes, habitat structure is frequently manipulated through the creation of features such as tracks, hedges, and waterways. If predator and prey activity are concentrated around these features, levels of predation may be elevated in these landscapes. This issue is of particular importance when habitat structures are used to attract species of conservation concern. For example, the installation of linear waterways in wet grasslands is a common form of habitat management to benefit breeding waders and wader nests and foraging chicks tend to be aggregated around wet features. If predator activity is also focused around these features, and if their linearity increases the probability of prey being located, then the conservation benefits of this management technique may be eliminated. We explore predator movement in relation to the structure and complexity of linear wet features within a lowland wet grassland landscape. We examine patterns of nest and chick predation in lapwing (Vanellus vanellus) at the whole-site, between-field and within-field scales. Mammalian predators were responsible for the majority of nest predation. However, we found no evidence that mammalian predators used linear wet features disproportionately within the landscape, or that wet feature distribution influenced the probability of nest or chick predation. At the whole-site scale, nest predation rates were significantly higher in areas with greater predator presence and lowest where the number of breeding neighbours was high. Thus, predation levels were influenced by large-scale patterns of predator presence and lapwing density but not by the use of linear wet features as a habitat management tool. Managing predator impacts is therefore likely to require empirical assessments of local predator distribution and abundance in order to target measures effectively.     

Predator-prey relationships and responses of ungulates and their predators to the establishment of protected areas: A case study of tigers, leopards and their prey in Bardia National Park, Nepal

Interactions among sympatric large predators and their prey and how they respond to conservation measures are poorly known. This study examines predictions concerning the effects of establishing a protected area in Nepal on tigers (Panthera tigris), leopards (Panthera pardus), and their ungulate prey. Within a part of the park, after 22 years the total density of wild ungulates had increased fourfold, to ca. 200 animals/km², almost exclusively due to a remarkable increase in chital deer (Axis axis). Tiger density also increased markedly to nearly 20 animals/100 km², whereas leopard density did not and was ca. 5 animals/100 km². The prediction that grazers should increase more than browsers was only partially supported. The prediction of positive density dependence in prey selection was not supported. Instead, the most abundant species (chital and hog deer, Axis porcinus) were killed less frequently than expected, whereas the lower-density wild boar (Sus scrofa) was preferred. Predictions that (i) initially rare species suffer highest predation was partially supported, that (ii) predation is highest among the most abundant prey was not supported, and that (iii) predation is highest among the most preferred prey independently of their densities was supported. Clearly, the conservation efforts adopted in Bardia were successful, as both tigers and their natural prey base increased. However, the positive numerical response of tigers limited and depressed the abundance of some prey species. Thus, conservation activities aimed at restoring large predators are likely to change in the composition of the overall mammal community, potentially eliminating rare but preferred prey species.     

海南坡鹿饲草粗蛋白质和微量元素含量与喜食性的关系

在海南大田国家级自然保护区围栏内,测定海南坡鹿饲草的喜食性;采集坡鹿经常采食的草本植物和灌木各18种,测定其粗蛋白质、铁、锰、锌和铜含量,并分析其与饲草喜食性的相关关系.结果显示,随着粗蛋白质和微量元素含量增加,饲草的喜食性显著提高,海南坡鹿优先摄取粗蛋白质和微量元素含量丰富的饲草.灌木类饲草的粗蛋白质、铁、锰、锌和铜含量分别为12.24%、265.44、61.43、26.72和17.82mg/kg,均显著高于草本类饲草含量(依次为9.39%、142.67、34.05、13.67和9.44mg/kg).灌木是海南坡鹿旱季长达半年多时间里在大田保护区围栏内得以维持平衡的生态营养需要的重要营养源.对海南坡鹿饲草资源量的研究表明,大田保护区围栏内坡鹿喜食的灌木类饲草的可采食资源量在逐步减少,这是由于它们被坡鹿长期选择性采食所导致的.     

Ability of heifers to discriminate between familiar herdmates and members of an unfamiliar group: preference test and operant conditioning test

Using a preference test and operant conditioning in a Y-maze, this experiment examined the ability of heifers to discriminate between their own familiar herdmates and member(s) of an unfamiliar group. Sixteen Danish Friesian heifers, eight older animals (360.6 ± 24.2 days of age) and eight younger ones (190.1 ± 14.1 days of age) were used. Each age group was further divided into two experimental groups. Members of each of these groups were housed together in small pens before the experiments began. In experiment 1, each of the 16 animals was allowed to approach either a familiar or an unfamiliar individual in the Y-maze. The test was repeated 12 times, with a different unfamiliar subject for each test. In experiment 2, eight heifers were individually tested in a conditioning experiment to examine whether they could learn to discriminate between a group of their three herdmates and a group of three unfamiliar heifers. Test animals were rewarded when they chose their own group. In experiment 1, heifers did not show a preference between familiar and unfamiliar individuals. Interestingly the younger stimulus heifers but not the test animals showed an ability to discriminate between unfamiliar animals by vocalizing. In experiment 2, four of the eight test animals achieved the criterion for successful discrimination between the familiar and unfamiliar group ( P  < 0.003: binomial law). There was no age group difference in the ability to discriminate between familiar and unfamiliar animals. In conclusion, heifers did not show a preference toward familiar or unfamiliar individuals; but after conditioning, some heifers could learn to discriminate between familiar and unfamiliar groups.     

基于主观偏好和景观空间指标的农业景观特征偏好模型: 以北京市11个农业景观特征区域为例

本研究以北京市11个农业景观特征区域的真实照片为评价资料,通过对46位环境相关专业大学生进行的平衡非完全区组排序评判测试得到他们对不同景观照片的偏好数值。以250m为边长的正三角形在2006年110000土地利用图上截取出照片所对应的数据,根据这些数据计算了反映该照片景观特征的空间格局指数。利用多元逐步回归,以相对应的空间格局指数以及主观判断得到的绿色覆盖度和管理水平等共11个指标,分别针对不同景观特征区域构建景观偏好模型。研究表明,除各指标在权重上的差异外,有些指标在不同特征区域内,甚至在对景观偏好影响的方向上都有所差异:绿色覆盖度、管理水平、斑块黏合度、斑块聚合程度、分维度指数均体现出对景观可视偏好的正向影响,开阔地比例在可视范围体现了对景观偏好的逆向影响,而斑块数量、蔓延度、最大斑块指数、干扰比例和林地比例在不同景观特征分区内则表现不同的影响趋向。     

Host preference of adult Caligus elongatus Nordmann in the laboratory and its implications for Atlantic cod aquaculture

The sea louse Caligus elongatus utilizes a range of marine fish species as hosts, and it has been suggested that fish farms are infected with adult C. elongatus from wild fish hosts. We assessed experimentally whether dislodged lice return to their original host species. Adult lice from wild lumpfish and saithe were presented to lumpfish, sea trout, Atlantic cod, saithe and European plaice. All fish species became infected. Lumpfish and cod were strongly preferred, followed by saithe, trout and plaice. Lice from wild saithe showed a preference for saithe and lumpfish, followed by cod, sea trout and plaice. The mtCO1 gene was used to determine the genotypes of the lice. Lice from lumpfish were genotype 1. Lice from saithe were mainly genotype 2. The two genotypes of C. elongatus differed slightly in their host preferences: lice from saithe were less discriminating. The data support the hypothesis that adult C. elongatus may transfer between different host species. Cod is an attractive host for lice from both lumpfish and saithe, which suggests that C. elongatus may become a serious pest of farmed cod.