Effects of predation and intraspecific interactions on habitat use and foraging by brown trout in artificial streams

Abstract— We studied habitat use, foraging rates and behavior of 10 cm and 12 cm long brown trout, Salmo trutta , at two densities, 1.5 and 3.0 fish. m⁻², in artificial streams that contained either the amphipod, Gammarus pulex , alone or G. pulex together with the piscivore, northern pike, Esox lucius. Gammarus were stocked in and largely restricted to the pools at a density of 128 Gammurus. m⁻² . pool⁻¹ Large trout (12 cm) used pools more and riffles less when small trout (10 cm) were present than when small trout were absent. Small trout consumed fewer Gammarus when together with large trout than when alone, but showed no difference in habitat use in the presence and abscnce of large trout. Habitat use and number of Gammarus consumed per trout were not affected by trout density for either size-class when alone. For both size-classes of trout, use of pools and foraging rates were higher in the absence than in the presence of pike, and pike primarily resided in the pools. The number of aggressive interactions by both size-classes of trout decreased when pike was present. Our results indicate that for habitats that differ in food resources and predation risk, size structure may affect habitat use and foraging by brown trout.     

丽江猪屠宰、胴体组成及肉质特性研究

丽江猪是近年在云南丽江新发现的猪种遗传资源,笔者对丽江猪的体型外貌、体尺、胴体组成及肉质性状等种质特性进行测定。结果：丽江猪公、母猪体重分别为（60.71±4.93） kg和（54.11±12.88） kg,体高分别为（65.72±6.11） cm和（64.66±6.10） cm,体长分别为（105.64±9.61） cm和（102.18±10.51） cm,眼肌面积分别为（24.13±6.08） cm2和（23.62±6.16） cm2,瘦肉率分别为（40.09±3.17）%和（41.71±5.05）%,失水率（19.50±5.03）%,粗脂肪（15.71±4.68）%,pH（6.18±0.13）,大理石纹（3.6±0.57）。丽江猪肉质各项指标均符合优质肉范畴,属于肉脂兼用型猪种,且含有丰富的脂肪酸,具有较高食用价值。     

饲料粉碎粒度和调质温度对肉鸡养分消化率及生长性能的影响

饲料制粒可以提高采食量和缩短采食时间,以提高肉鸡生长性能和饲料转化率.而原料的粉碎和调质是制粒过程中非常重要的环节,不仅直接影响到饲料的营养价值和肉鸡的消化吸收,还会影响加工成本和产品质量.粉碎粒度过大会导致混合不均匀、颗粒品质欠佳等不利影响,并且对动物的采食及采食后的物理性消化产生影响,粒度过小则会对动物健康产生不利影响.调质过程主要是使饲料受到水热作用,使其蛋白质变性、淀粉糊化等,调质温度是调质环节的关键参数,温度的高低对蛋白质变性及淀粉糊化程度有直接影响,从而间接影响到动物的生长性能和养分消化利用率.同时,调质温度过高会导致饲料中添加的酶制剂及维生素等严重失活,反而会降低饲料的营养价值.本文综述了肉鸡饲料粉碎粒度和调质温度的研究进展,阐述了粉碎粒度、调质温度与肉鸡生长性能和养分消化率的重要关系.     

养殖环境细菌微生物气溶胶粒径分布及其健康危害评估

为深入了解畜禽舍环境中气载细菌微生物的空气动力学粒径分布规律,并评估其潜在的健康危害风险,采用Andersen-6级微生物空气采样器以血-琼脂培养基、沙氏培养基和高氏合成1号培养基为采样介质,对鸡舍、猪舍、牛舍环境中空气样品进行系统定点取样、测定及分析。研究结果表明,鸡舍环境中气载需氧菌含量最高,猪舍次之,牛舍最低;空气细菌粒径分布均为第Ⅰ级最高,鸡舍空气粒径呈偏态分布,牛舍、猪舍分别在第Ⅲ级和第Ⅳ级出现第2个峰值。携带细菌可吸入微粒在猪舍环境中比例最大。空气真菌与放线菌均在第Ⅳ级最高,携带真菌和放线菌可吸入粒子的比例显著大于细菌（P<0.05）。鸡舍、猪舍、牛舍空气微生物粒径各级分布比例基本一致。在鸡舍、猪舍、牛舍每天约有6.1×105CFU、4.7×104CFU和3.6×104CFU气载细菌微生物可分别进入人和动物小支气管或直接进入肺泡,从而对人和动物健康构成潜在危害。     

The use of a pen-size optimization workbook for experiment research design using the Visual Basic for Applications in Excel for poultry

Researchers often seem to choose the number of birds per pen and replications per treatment somewhat arbitrarily on the basis of cost, availability of animals, housing considerations, convenience, tradition, and so on. Statistical simulation, performed while designing an experiment, will provide a researcher with an objective estimate of the number of birds per pen and replicates needed for an experiment of known Type I and II errors. In most cases, the time for making power calculations should be before, not after, an experiment is conducted. Here we present a Microsoft Excel workbook to explore the statistical and economic ramifications of different combinations of birds per replicate and replicates per treatment for research with poultry.     

An assessment of reproductive and lifetime performances of Kagoshima Berkshire gilts and sows

We investigated the reproductive and lifetime performances of Kagoshima Berkshire gilts and sows. We examined 20 605 parity records of 4419 pigs for 2008 to 2012 on a farrow‐to‐finish commercial farm. The mean parity (± SD) of all animals was 3.0 ± 2.1. For farrowing performance, the highest numbers of total pigs born and pigs born alive were found in sows with parities 5 and 6 and with parity 3–6, respectively (P < 0.05). Regarding weaning and mating performance, sows with parity 2 had the lowest preweaning mortality (P < 0.05). The longest weaning‐to‐first‐mating interval was found in parity 1 pigs, and the interval decreased as parity increased (P < 0.05). Parities 0 and 1 pigs had the lowest farrowing rate and those with parity 4 had the highest farrowing rate (P < 0.05). The mean parity at culling, total number of pigs born alive in a lifetime, and nonproductive days in a lifetime were 5.5 ± 2.93, 49.2 ± 24.72 pigs, and 132.1 ± 83.34 days, respectively. These animals had a lower litter size and fertility that the F₁ crossbred sows mainly used in Japan, but a similar tendency for performance by parity.     

代乳粉对早期断奶犊牛体重和体尺的影响

试验选取体重相近的荷斯坦奶牛犊牛24头,分为试验组和对照组2组,每组12头。试验组犊牛出生5 d内饲喂初乳,之后饲喂代乳粉至42日龄断奶;对照组一直饲喂牛奶至42日龄。结果表明,试验组平均日增重836 g,对照组平均日增重679 g,试验组比对照组日增重提高23.12%;试验期间,试验组胸围、体高、体长分别比对照组提高2.90、1.01、1.56 cm,差异不显著;试验组与对照组的管围无明显差异。说明代乳粉代替牛乳可以达到良好的生产效果。     

Latitudinal and seasonal variation in reproductive effort of the eastern fence lizard (Sceloporus undulatus)

Geographic variation in life‐history traits among populations of wide‐ranging species is influenced by both spatial and temporal aspects of the environment. Rarely, however, are the effects of both aspects examined concurrently. We collected gravid female lizards (Sceloporus undulatus) from northern (Indiana), central (Mississippi) and southern (Florida) populations, spanning nearly the full latitudinal range of the species, to examine amongpopulation differences in strategies of reproductive energy allocation. Adult females from the southern population were smaller, and produced fewer and smaller eggs in their first clutches than did females from the more northern populations. Southern females were more likely to produce a second clutch, and second clutches were smaller than first clutches for females from the 2 northern populations. Together these trends eliminated population differences in overall reproductive output after accounting for body size. The trend for greater reproductive energy to be allocated to first clutches at higher latitudes, and to later clutches at lower latitudes is corroborated by published data from field studies on multiple populations. Distributing reproductive effort by producing more clutches of smaller eggs may be an adaptive response to the long season available for egg incubation and lizard activity in sub‐tropical southern environments. In contrast, allocating greater resources to early reproduction may enhance maternal fitness in the relatively short activity seasons that characterize more northern sites.