Estimates of daily oxygen consumption,carbon dioxide and methane emissions,and heat production for beef and dairy cattle using spot gas sampling

A simulation study was conducted to examine accuracy of estimating daily O₂ consumption, CO₂ and CH₄ emissions, and heat production (HP) using a spot sampling technique and to determine optimal spot sampling frequency (FQ). Data were obtained from 3 experiments where daily O₂ consumption, emissions of CO₂ and CH₄, and HP were measured using indirect calorimetry (respiration chamber or headbox system). Experiment 1 used 8 beef heifers (ad libitum feeding; gaseous exchanges measured every 30 min over 3 d in respiration chambers); Experiment 2 used 56 lactating Holstein-Friesian cows (restricted feeding; gaseous exchanges measured every 12 min over 3 d in respiration chambers); Experiment 3 used 12 lactating Jersey cows (ad libitum feeding; gaseous exchanges measured every hour for 1 d using headbox style chambers). Within experiment, averages of all measurements (FQALL) and averages of measurements selected at time points with 12, 8, 6, or 4 spot sampling FQ (i.e., sampling every 2, 3, 4, and 6 h in a 24-h cycle, respectively; FQ12, FQ8, FQ6, and FQ4, respectively) were compared. Within study a mixed model was used to compare gaseous exchanges and HP among FQALL, FQ12, FQ8, FQ6, and FQ4, and an interaction of dietary treatment by FQ was examined. A regression model was used to evaluate accuracy of spot sampling within study [i.e., FQALL (observed) vs. FQ12, FQ8, FQ6, or FQ4 (estimated)]. No interaction of diet by FQ was observed for any variables except for CH₄ production in experiment 1. No FQ effect was observed for gaseous exchanges and HP except in experiment 2 where CO₂ production was less (5,411 vs. 5,563 L/d) for FQ4 compared with FQALL, FQ12, and FQ8. A regression analysis between FQALL and each FQ within study showed that slopes and intercepts became farther from 1 and 0, respectively, for almost all variables as FQ decreased. Most variables for FQ12 and FQ8 had root mean square prediction error (RMSPE) less than 10% of the mean and concordance correlation coefficient (CCC) greater than 0.80, and RMSPE increased and CCC decreased as FQ decreased. When a regression analysis was conducted with combined data from the 3 experiments (mixed model with study as a random effect), results agreed with those from the analysis for the individual studies. Prediction errors increased and CCC decreased as FQ decreased. Generally, all the estimates from FQ12, FQ8, FQ6, and FQ4 had RMSPE less than 10% of the means and CCC greater than 0.90 except for FQ6 and FQ4 for O₂ consumption and CH₄ production. In conclusion, the spot sampling simulation with 3 indirect calorimetry experiments indicated that FQ of at least 8 samples (every 3 h in a 24-h cycle) was required to estimate daily O₂ consumption, CO₂ and CH₄ production, and HP and to detect changes in those in response to dietary treatments. This sampling FQ may be considered when using techniques that measure spot gas exchanges such as the GreenFeed and face mask systems.     

Advances in bio-logging techniques and their application to study navigation in wild seabirds

ABSTRACT

This review summarizes the advances in bio-logging technology that enables us to monitor foraging behavior, movement, behavioral performance, physiological performance, and sociality in a wide range of bird species, as well as their habitat. Subsequently, navigation is discussed, using long-distance movements in streaked shearwaters as a case study. Moreover, challenges and future research directions in bio-logging science are presented, with focus on: multimodal recording, big data analysis, feedback logging, low-power consumption and power generation systems, logger effects, and capture–recapture methods.     

Antimicrobial residues survey by LC-MS in food-producing animals in Lebanon

ABSTRACT

The treatment of animals with antimicrobial products may lead to the contamination of edible tissues by their residues, which may represent a risk to human health. Therefore, this study aimed to determine the level of antimicrobial residues in food-producing animals (chicken, beef, and milk) in Lebanon. A total of 310 samples were collected and analysed using an LC-MS/MS for the determination of 48 compounds belonging to different families in order to map their compliance according to the European Commission decision 2002/657/EC. Results show that 60% of the analysed samples were not contaminated by any residue, while 12% presented a concentration higher than the MRLs for tetracyclines, sulphonamides, quinolones, and macrolides. Results revealed that chicken were the most contaminated by antimicrobial residues, when compared to beef and milk. The obtained results demonstrate the uncontrolled use of antimicrobials in some Lebanese farms and claim for better management of livestock.     

A Chamber for Testing the Release of Volatile Substances Secreted by Animals,Especially Mammals,as Exemplified by Substances Released by Rats in Response to Stress

Abstract

The success of the testing of volatile organic compounds emitted by animals is dependent on the creation of appropriate conditions for air sampling subsequently used to assay and identify the compounds. These conditions play a particularly important role in the investigation of pheromones, which are secreted in extremely low concentrations. The authors have not come across any previous work which offers constructional solutions, which would allow avoidance of contamination of the air samples containing volatile substances secreted by animals.

A constructional solution was developed, which provides optimal conditions for their sampling and isolation. Its main advantages are as follows: the exposure chamber (the chamber in which the animal is studied) is filled with synthetic air; the exposure chamber is separated from the atmospheric air with a synthetic air “jacket”; the exposure chamber has been constructed using materials which do not release chemicals and absorb them in trace quantities.     

Renting with pets: a pathway to housing insecurity?

Companion animals are rarely considered in rental policy or research. This absence belies their prevalence and growing centrality within practices of family and home, and persists despite evidence of links between companion animals and rental insecurity. This paper begins to address this gap. Through an online survey and in-depth interviews with people who rented with companion animals in Sydney, Australia, over the 10 years to 2013, the paper identifies connections between pet ownership and rental insecurity, including perceptions about the low availability and poor quality of advertised ‘pet-friendly’ properties. The paper argues that pet ownership can trigger feelings of rental insecurity, and advocates for inclusion of pet ownership as a variable impacting secure occupancy. It suggests companion animals are an escalating rental risk, their significance to their owners causing some to accept accelerating levels of rental insecurity by keeping pets without landlord knowledge. These experience impact on the ability of renters to feel ‘at home’ in rental properties.     

紫草多糖对培养大鼠颗粒细胞生成甾体激素的影响

目的研究中药紫草的水溶成分——紫草多糖对体外培养颗粒细胞的直接作用。方法分离出大鼠双侧卵巢的颗粒细胞进行体外培养。选取健康未成年雌性SD大鼠160只,其中60只按随机数字表法分为基础组和hCG组,分别采用不同浓度（0.00、0.30、0.75、1.50、3.00、7.50 g·L^-1）紫草多糖培养,每组5只;另100只按随机数字表法分为空白对照组、紫草多糖组、hCG组和hCG-紫草多糖组,分别进行不同时间（0、1、2、3、4 h）的培养,每组5只,共计100只。采用放射免疫测定法（RIA）测定不同实验组颗粒细胞培养液中孕酮（Progesterone,P4）和雌二醇（Estradiol,E2）的浓度。结果紫草多糖呈剂量依赖性地抑制hCG刺激下颗粒细胞P4和E2的生成,大剂量（大于3.00 g·L^-1）也抑制基础P4和E2的生成,紫草多糖主要使培养液中的P4含量降低,但大剂量也可使细胞内的P4含量降低。紫草多糖作用于颗粒细胞1 h后明显抑制hCG促P4生成的作用,但细胞洗涤后再培养,对hCG的反应性与对照组比较无明显变化。结论紫草多糖可直接作用于体外培养的颗粒细胞,抑制hCG促甾体激素生成的作用,该抑制作用起效时间短,并且是可逆的。     

依达拉奉对大鼠缺血再灌注心肌的保护作用

目的 探讨依达拉奉对心肌缺血再灌注的保护作用及机制.方法 将50只成年SD大鼠按随机数字表法分为假手术组、再灌注组、低剂量组、中剂量组和高剂量组,每组10只.建立大鼠急性缺血再灌注模型,描记术中心电图变化.假手术组：开胸,分离左冠状动脉并穿线,不结扎,旷置225 min;再灌注组：缺血45 min,再灌注3 h,灌注前1 min将生理盐水按0.2 mL·kg-1经右股静脉注入;低剂量组：再灌注前1 min,将依达拉奉按3 mg·kg-1经右股静脉注入;中剂量组：灌注前1 min将依达拉奉按6 mg·kg-1经右股静脉注入;高剂量组：灌注前1 min将依达拉奉按9 mg·kg-1经右股静脉注入.于再灌注末测定血清肌钙蛋白、心肌组织Ca2＋、SOD、MDA及Na＋-K＋-ATPase 、Ca2＋-ATPase的含量或活性.结果 再灌注组与低剂量组、中剂量组、高剂量组相比,再灌注后ST段回落程度较低、室性心律失常发作例数稍高,但4组间比较差异均无统计学意义（均P＞0.05）.低剂量组、中剂量组和高剂量组的血清肌钙蛋白明显低于再灌注组（均P＜0.05）;中剂量组、高剂量组及再灌注组血清肌钙蛋白明显高于假手术组（P＜0.05或P＜0.01）.与假手术组比较,再灌注组心肌组织MDA活性、Ca2＋含量明显增高,SOD活力及Na＋-K＋-ATP酶、Ca2＋-ATP酶活性明显降低（均P＜0.05）;与再灌注组比较,低剂量组、中剂量组和高剂量组的MDA活力及Ca2＋含量降低,SOD活力及Na＋-K＋-ATP酶、Ca2＋-ATP酶活性明显增加（均P＜0.05）.结论 在再灌注前注射依达拉奉可减轻心肌缺血再灌注损伤.其作用机制是有效地清除氧自由基、提高机体抗氧化应激能力.     

超声引导双心房输注技术对犬急性肺动脉高压血流动力学的影响

目的 探讨超声引导双心房输注技术对犬急性肺动脉高压（APH）血流动力学的影响.方法 将健康成年杂种犬10只按随机数字表法分为超声引导组（A组）、开胸组（B组） 2组,每组5只.2组均采用氯胺酮10 mg·kg-1肌内注射进行麻醉,按经肺动脉注入血栓栓塞法建立犬APH模型,建模成功后：A组通过Swan-Ganz漂浮导管至右心房给予前列腺素E1脂微球载体制剂（Lipo-PGE1）20Jng·kg-1·min-1,通过超声引导,经股动脉逆行置入左心导管至左心房,给予去氧肾上腺素2 μg·kg-1·min-1;B组通过Swaw-Ganz导管至右心房给予A组相同剂量的前列腺素E1脂微球载体制剂,经胸正中切口开胸,经左心耳分别插入左心导管,给予A组相同剂量去氧肾上腺素.测量2组麻醉前（T1）,建模成功后给药前（T2）,给药后10tmin（T3）、30 min（T4）、60 min（T5）的心率（HR）、平均动脉压（MAP）、血氧饱和度（SpO2）、中心静脉压（CVP）、平均肺动脉压（MPAP）、肺毛细血管楔压（PCWP）和心排出量（CO）,计算心指数（CI）、全肺阻力指数（PVRI）和体循环阻力指数（SVRI）,并检测各时点的血浆LDH3.结果 2组均制模成功.与T2比较：2组T3-T5 时段MPAP、PVRI值均有显著下降（P＜0.05）; 2组T3-T5 时段CI、MAP和SVRI值均有所上升,但差异无统计学意义（P＞0.05）; 2组T4、T5 时段LDH3值均有显著下降（P＜0.05）.各观察指标2组间各时点比较差异均无统计学意义（P＞0.05）.结论 超声引导双心房输注给予前列腺素E1脂微球载体制剂和去氧肾上腺素能够有效地降低肺动脉高压,同时改善心脏做功,提高CI,降低对体循环血流动力学的影响,改善急性肺动脉高压低心排出量;在减小创伤的同时达到与开胸双心房输注同样效果.     

地锦草水提液对糖尿病小鼠的降血糖作用

目的观察地锦草水提液对糖尿病小鼠的降血糖作用,并探究其作用机制。方法对60只小鼠进行尾静脉注射0.25%四氧嘧啶溶液80mg·kg-1,注射后2h给予50%葡萄糖溶液0.2mL·10g-1灌胃造模,3d后眼眶采血测血糖,血糖值〉11.1mmol·L-1为糖尿病小鼠。将50只造模成功的小鼠按随机数字表法分为5组：NS组（阴性对照组）,地锦草低（59mg·kg-1·d-1）、中（118mg·kg-1·d-1）、高（236mg·kg-1·d-1）剂量组,二甲双胍组（阳性对照组）,每组10只。连续给药14d后,观察地锦草水提液对糖尿病小鼠血糖、血清胰岛素、胰岛病理形态变化的影响。结果 1）备糖：地锦草高剂量组和二甲双胍组给药后的血糖明显低于给药前及NS组,地锦草低、中剂量组（均P〈0.05）,NS组、地锦草中、低剂量组血糖也略下降,但差异均无统计学意义（均P〉0.05）。2）血清胰岛素：地锦草高剂量组、二甲双胍组血清胰岛素水平均显著高于NS组及地锦草低、中剂量组（均P〈0.05）,地锦草低、中剂量组及NS组比较差异均无统计学意义（均P〉0.05）。3）胰腺的病理形态：NS组胰岛数量明显减少,结构破坏,边界模糊不清,胰岛β细胞排列紊乱,部分细胞出现变性或坏死;地锦草各剂量组胰岛数量较多,胰岛结构较完整,境界较清晰,胰岛β细胞排列较整齐,细胞形态较好,胞浆丰富,胞核多数清楚,仅可见少数细胞变性或坏死;二甲双胍组胰岛形态有一定的恢复。结论地锦草水提液对糖尿病小鼠的降血糖作用可能是通过保护胰岛β细胞、减轻其损伤及增加胰岛素分泌来实现。     

畜类屠宰加工行业竣工环保验收监测的要点

随着我国经济持续发展,屠宰及肉类加工行业发展势头良好,行业规模稳步扩大,在满足消费需求的同时,也带来了一系列环保问题。根据畜类屠宰加工行业的特点,本文归纳并阐述了该类项目竣工环境保护验收监测中应重点关注的的几个问题,从而为这类项目的竣工环保验收监测工作提供参考。