Sources and significance of variation in basal,summit and maximal metabolic rates in birds

The rates at which birds use energy may have profound effects on fitness, thereby influencing physiology, behavior,ecology and evolution. Comparisons of standardized metabolic rates (e.g., lower and upper limits of metabolic power output)present a method for elucidating the effects of ecological and evolutionary factors on the interface between physiology and lifehistory in birds. In this paper we review variation in avian metabolic rates [basal metabolic rate (BMR; minimum normothermicmetabolic rate), summit metabolic rate (M_(sum); maximal thermoregulatory metabolic rate), and maximal metabolic rate (MMR;maximal exercise metabolic rate)], the factors associated with this variation, the evidence for functional links between thesemetabolic traits, and the ecological and evolutionary significance of avian metabolic diversity. Both lower and upper limits tometabolic power production are phenotypically flexible traits, and vary in association with numerous ecological and evolutionaryfactors. For both inter- and intraspecific comparisons, lower and upper limits to metabolic power production are generallyupregulated in response to energetically demanding conditions and downregulated when energetic demands are relaxed, or underconditions of energetic scarcity. Positive correlations have been documented between BMR, M_(sum) and MMR in some, but not allstudies on birds, providing partial support for the idea of a functional link between lower and upper limits to metabolic powerproduction, but more intraspecific studies are needed to determine the robustness of this conclusion. Correlations between BMRand field metabolic rate (or daily energy expenditure) in birds are variable, suggesting that the linkage between these traits is subjectto behavioral adjustment, and studies of the relationship between field and maximal metabolic rates are lacking. Our understandingof avian metabolic diversity would benefit from future studies of: (1) the functional and mechanistic links between lowerand upper limits of metabolic power output; (2) the environmental and ecological cues driving phenotypically flexible metabolicresponses, and how responses to such cues might impact population responses to climate change; (3) the shapes of metabolic reactionnorms and their association with environmental variability; and (4) the relationship of metabolic variation to fitness, includingstudies of repeatability and heritability of minimum and maximum metabolic power

Seasonal acclimatization and temperature acclimation in small passerine birds is achieved via metabolic adjustments

Temperature and other environmental factors play an integral role in the metabolic adjustments of animals and drive a series of morphological,physiological,and behavioral adaptions essential to survival.However,it is not clear how the capacity of an organism for temperature acclimation translates into seasonal acclimatization to maintain survival.Basal metabolic rate(BMR),evaporative water loss(EWL),and energy budget were measured in the Chinese Hwamei(Garrulax canorus)following winter and summer acclimatization,and in those acclimatized to 15℃(cold)and 35℃(warm)under laboratory conditions for 28 days.In addition to the above indicators,internal organ masses,as well as state 4 respiration and cytochrome c oxidase(COX)activity were also measured for the liver,skeletal muscle,heart,and kidney.Both winter-acclimatized and cold-acclimated birds exhibited significantly higher BMR,EWL,and energy budget,as well as organ masses,state 4 respiration,and COX activity compared with the summer-acclimatized and warm-acclimated birds.This indicated that the Chinese Hwamei could adapt to seasonal or just temperature changes through some physiological and biochemical thermogenic adjustments,which would be beneficial to cope with natural environmental changes.A general linear model showed that body mass,BMR,GEI,state 4 respiration in the liver and kidney,and COX activity in the skeletal muscle,liver,and kidney were significantly affected by temperature and acclimation.A positive correlation was observed between BMR and each of the other parameters(body mass,EWL,energy budget,heart dry mass,kidney dry mass,state 4 respiration)in the muscle,heart,and kidney and also between BMR and COX activity in the muscle and kidney.The results suggested that similar to seasonal acclimatization,Chinese Hwameis subjected to temperature acclimation also exhibited significant differences in metabolism-related physiological and biochemical parameters,depending on the temperature.The data also supported the prediction that metabolic adjustment might be the primary means by which small birds meet the energetic challenges triggered by cold conditions.

Metabolic rate and evaporative water loss in the silky starling （Sturnus sericeus）

To better understand the physiological characteristics of the silky starling(Sturnus sericeus), its body temperature(Tb), basal metabolic rate(BMR), evaporative water loss(EWL) and thermal conductance(C) elicited by different ambient temperatures(Ta)(5-30 °C) were determined in the present study. Our results showed that they have a high Tb(41.6±0.1 °C), a wide thermal neutral zone(TNZ)(20-27.5 °C) and a relatively low BMR within the TNZ(3.37±0.17 mL O2/g·h). The EWL was nearly stable below the TNZ(0.91±0.07 mg H2O/g·h) but increased remarkably within and above the TNZ. The C was constant below the TNZ, with a minimum value of 0.14±0.01 mL O2/g·h·°C. These findings indicate that the BMR, Tb and EWL of the silky starling were all affected by Ta, especially when Ta was below 20 °C and the EWL plays an important role in thermal regulation.

Short photoperiod increases energy intake, metabolic thermogenesis and organ mass in silky starlings Sturnus sericeus

Environmental cues play important roles in the regulation of an animal＇s physiology and behavior. One such cue, photoperiod, plays an important role in the seasonal acclimatization of birds. It has been demonstrated that an animal＇s body mass, basal metabolic rate （BMR）, and energy intake, are all affected by photoperiod. The present study was designed to examine photoperiod induced changes in the body mass, metabolism and metabolic organs of the silky starling, Stumus sericeus. Captive silky starlings increased their body mass and BMR during four weeks of acclimation to a short photoperiod. Birds acclimated to a short photopedod also increased the mass of certain organs （liver, gizzard and small intestine）, and both gross energy intake （GEl） and digestible energy intake （DEI）, relative to those acclimated to a long photoperiod. Furthermore, BMR was positively correlated with body mass, liver mass, GEl and DEI. These results suggest that silky starlings increase metabolic thermogenesis when exposed to a short photoperiod by increasing their body and metabolic organ mass, and their GEl and DEI. These findings support the hypothesis that bird species from temperate climates typically display high phenotypic flexibility in thermogenic capacity.

Relationships between interspecific differences in the mass of internal organs,biochemical markers of metabolic activity,and the thermogenic properties of three smallpasserines

Background:The capacity for thermogenesis is considered part of an animal's adaptive strategy for survival,and basal metabolic rate(BMR) is one of the fundamental physiological standards for assessing the energy cost of thermoregulation in endotherms.BMR has been shown to be a highly flexible phenotypic trait both between,and within,species,but the metabolic mechanisms involved in the regulation of BMR,which range from variation in organ mass to biochemical adjustments,remain unclear.In this study,we investigated the relationship between organ mass,biochemical markers of metabolic tissue activity,and thermogenesis,in three species of small passerines:wild Bramblings(Fringilla montifringilla),Little Buntings(Emberiza pusilla) and Eurasian Tree Sparrows(Passer montanus),caught in Wenzhou,southeastern China.Methods:Oxygen consumption was measured using an open-circuit respirometry system.Mitochondrial state-4 respiration and cytochrome c oxidase(COX) activity in liver and pectoral muscle were measured with a Clark electrode.Results:Our results show that Eurasian Tree Sparrows had significantly higher BMR,digestive organ mass,mitochondrial state-4 respiration capacity and COX activity in liver and muscle,than Bramblings and Little Buntings.Furthermore,interspecific differences in BMR were strongly correlated with those indigestive tract mass,state-4 respiration and COX activity.Conclusions:Our findings suggest that the digestive organ mass,state-4 respiration and COX activity play an important role in determining interspecific differences in BMR.

The role of temperature as a driver of metabolic flexibility in the Red-billed Leiothrix(Leiothrix lutea)

Background:The thermoregulatory ability of animals is strongly influenced by the temperature of their environment.Acclimation to cold requires a range of physiological and morphological adjustments.In this study,we tested the hypothesis that a small passerine,the Red-billed Leiothrix(Leiothrix lutea),can maintain homeothermy in cold conditions by adjusting the physiology and biochemistry of its tissue and organs and return to its former physiological and biochemical state when moved to a warm temperature.Methods:Phenotypic variation in thermogenic activity of the Red-billed Leiothrixs(Leiothrix lutea)was investigated under warm(35℃),normal(25℃)or cold(15℃)ambient temperature conditions.Oxygen consumption was measured using an open-circuit respirometry system.Mitochondrial state-4 respiration and cytochrome-c oxidase(COX)activity in liver,kidney heart and pectoral muscle were measured with a Clark electrode.Results:Birds acclimated to an ambient temperature of 15℃ for 4 weeks significantly increased their basal metabolic rate(BMR)compared to a control group kept at 25℃.Birds acclimated to 35℃ decreased their BMR,gross energy intake(GEI)and digestible energy intake(DEI).Furthermore,birds acclimated to 15℃ increased state-4 respiration in their pectoral muscles and cytochrome-c oxidase(COX)activity in their liver and pectoral muscle,compared to the 25℃ control group.Birds acclimated to 35℃ also displayed lower state-4 respiration and COX activity in the liver,heart and pectoral muscles,compared to those kept at 25℃.There was a positive correlation between BMR and state-4 respiration,and between BMR and COX activity,in all of the above organs except the liver and heart.Conclusions:Our study illustrates that the morphological,physiological,and enzymatic changes are associated with temperature acclimation in the Red-billed Leiothrix,and supports the notion that the primary means by which small birds meet the energetic challenges of cold conditions is through metabolic adjustments.

On the intraspecific variability in basal metabolism and the food habits hypothesis in birds

The food habits hypothesis (FHH) stands as one of the most striking and often-cited interspecific patterns to emergefrom comparative studies of endothermic energetics. The FHH identifies three components of diet that potentially produce variabilityin mass-independent BMR, i.e. food quality, food availability, and food predictability or environmental productivity. Thehypothesis predicts that species with diets of low energy content and/or low digestibility should evolve low mass-independentBMRs. The effects of food habits on BMR have been widely investigated at the interspecific level, but the variation between individualsand populations has been largely ignored. Our focus is to compare predictions derived from interspecific studies withdata collected from within-species studies to explore the mechanisms and functional significance of adaptive responses predictedby the food-habits hypothesis among birds. We conclude that if BMR is correlated with daily energy expenditure, then organismsthat can lower BMR will reduce daily energy expenditure and hence, food requirements. Birds that lower BMR in stressful environmentsmay increase survival. Nevertheless, the mechanism (s) by which birds eating a low quality diet reduce BMR andwhether lower BMR affects fitness remain to be

New Mathematical Modelling on BMR and Weight Prediction for Ghanaians

Background: Basal Metabolic Rate (BMR) is the quantum of calories needed for optimum body function when at rest. This has long been an indicator of one’s health and the basis for determining the metabolic age of individuals. Many scholastic projects have led to the establishment of mathematical models and inventions that measure the BMR and other body composition parameters. However, existing computations have limitations as they do not offer accurate results for Ghanaians. Aim: The purpose of the study was to model BMR metrics that are most suitable for Ghanaians and to investigate the effect of caloric difference on weight, Lean Body Mass (LBM) and % fat composition that can be implemented with Information Technology. Research Methods and Procedures: This was an experimental study that adopted a quantitative approach. BMR and body composition were measured in a sample of 242 Ghanaian adults (141 males and 101 females) from 19 to 30 years of age. Body composition was measured using bioelectrical impendence analysis (BIA) in all participants. Each participant was under study for 7 days. A simple linear regression model was used to examine associations between BMR/calorie intake and total body weight and LBM. Results: There was a significant statistical relation between BMR and LBM and between BMR and weight of both men and women. Equations for BMR and weight were established for males and females. Furthermore, caloric intake differences affected changes in total weight as well as differences in % fat composition. Caloric intake however did not affect the difference in LBM. Conclusion: Caloric difference had an impact on total body weight and Lean Body Mass. The model derived from the study predicts weight change and BMR of Ghanaians from 19 to 30 years of age. It is termed the Health and Age Monitoring System (HAMS).

中国佤族的体表面积与基础代谢率

目的:了解中国佤族的体表面积与基础代谢率。方法:根据《人体测量手册》的规定,调查了云南佤族1009例成人(男性499例,女性510例)的身高与体质量,并根据Yu公式计算其体表面积数据,根据Mifflin公式计算其基础代谢率,用Excel 2003和SPSS 19.0对数据进行统计分析。结果:佤族成年男性的基础代谢率为(1389.5±137.3)kcal/d,体表面积为(1.6088±0.1261)m^(2),佤族成年女性的代谢率为(1089.1±132.9)kcal/d,体表面积为(1.4783±0.1319)m^(2)。佤族成年男性和女性的基础代谢率均与年龄呈负相关,与体表面积之间呈正相关。佤族成人指标年龄组间的方差分析差异具有统计学意义。同年龄段佤族男性的基础代谢率和体表面积均大于女性。结论:佤族成年男性的基础代谢率和体表面积与夏尔巴人、克木人较为相近,女性与八甲人较为相近,可为修订我国能量推荐摄入量值提供参考。

黑线仓鼠的BMR个体差异及其应对高脂食物的能量学对策

为探讨高脂食物对小型哺乳动物能量代谢的影响及其与基础代谢率(Basal metabolic rate,BMR)的关系,将成年雌性黑线仓鼠(Cricetulus barabensis)分为高、低BMR组,每组再随机分为低脂、高脂食物组,驯化6周后,测定体重、摄入能和代谢率,以及消化酶活力、褐色脂肪组织(Brown adipose tissue,BAT)和主要内脏器官与肌肉的细胞色素c氧化酶(Cytochrome c oxidase,COX)活性、解偶联蛋白(Uncoupling protein,UCP)mRNA表达等。结果显示,高脂食物对高、低BMR组动物体重均无显著影响。与低脂食物组相比,高脂食物组的摄食量、摄入能和消化能显著下降,小肠脂肪酶活力显著增强,消化率明显增加,但高、低BMR组的组间差异不显著。夜间代谢水平显著高于昼间,高脂食物使高BMR组的夜间代谢率显著升高。BAT、肌肉和内脏器官COX活性不受高脂食物的影响,高、低BMR组的组间差异也不显著。高脂食物组仅肝脏UCP_2表达显著上调。结果表明,能量摄入和消化系统形态及功能的可塑性调节是黑线仓鼠应对高脂食物的主要策略;黑线仓鼠的代谢率具有显著的昼夜节律,既受高脂食物的影响,也与动物自身的BMR水平有关,但UCP表达具有组织特异性,这可能不是导致BMR个体差异的因素。

宁夏某高校大学生瘦体组织成分与指长比的相关性研究

目的以宁夏某高校大学生为研究对象,分析瘦体组织(LBM)成分与指长比[食指(2D)︰环指(4D)]的相关性。方法随机选取838名在校大学生(男412名,女426名)为研究对象,采用生物电阻抗分析法测定所有受试者体重、身高、身体总水分(TBW)、细胞内液(ICW)、细胞外液(ECW)、蛋白质含量、骨矿物质含量(BMC)、骨骼肌含量(SMM)、体重指数(BMI)及基础代谢率(BMR)的分布。同时,拍摄受试者双手掌面照片,利用电脑图像软件测量并计算左、右手各2D︰4D。应用Pearson相关分析法及线性回归法分析各项LBM与2D︰4D的相关性。结果宁夏某高校大学生LBM、BMI和BMR的分布均表现为男性显著高于女性,差异有统计学意义(P<0.05);宁夏某高校大学生左手及右手2D︰4D均表现为女性显著高于男性,差异有统计学意义(P<0.05)。所有体成分指标在不同性别间均与2D︰4D无相关性(P>0.05)。结论宁夏某高校大学生LBM与2D︰4D均分别存在显著性别差异,提示性激素代谢水平可能影响二者的分布,然而两者之间并无相关性,可能并不存在共同的发育基础。

基础代谢率与椎间盘退变因果关系的孟德尔随机化研究

目的:探讨基础代谢率与椎间盘退变的因果关系。方法:分别从IEU OpenGWAS project数据库和FINNGEN数据库中筛选,获得基础代谢率的全基因组关联研究(genome-wide association study,GWAS)数据集和椎间盘退变的GWAS数据集。在分析工具R包中从基础代谢率的GWAS数据集中筛选符合要求的单核苷酸多态性(single nucleotide polymorphism,SNP)位点作为工具变量,根据筛选出的工具变量从椎间盘退变数据集中匹配相应的SNP位点。采用逆方差加权法(inverse variance weighted,IVW)、MR-Egger回归、简单中位数法(simple mode,SM)、加权中值法(weighted median estimator,WME)、加权中位数法(weighted mode,WM)进行孟德尔随机化(Mendelian randomization,MR)分析。采用MR-Egger截距检验、Cochran’s Q检验、留一法进行敏感性分析。结果:纳入90个基础代谢率SNP位点作为工具变量。MR分析结果显示,基础代谢率与椎间盘退变呈负向因果关系[IVW:OR=0.69,95%CI(0.59,0.80),P=0.000;WME:OR=0.69,95%CI(0.58,0.81),P=0.000;MR-Egger:OR=0.59,95%CI(0.42,0.84),P=0.004;WM:OR=0.59,95%CI(0.44,0.81),P=0.001;SM:OR=0.91,95%CI(0.57,1.47),P=0.710]。MR-Egger截距检验结果表明,MR分析结果不存在水平多效性(P=0.358)。异质性检验结果显示,基础代谢率SNP位点存在异质性(P=0.000);采用IVW的随机效应模型再次评估,结果显示基础代谢率与椎间盘退变呈负向因果关系(P=0.000),异质性存在对结果无影响;留一法检验结果显示,无单个SNP位点对基础代谢率与椎间盘退变呈负向因果关系造成影响,MR分析结果稳定。结论:基础代谢率与椎间盘退变呈负向因果关系。

Seasonal phenotypic flexibility in body mass,basal thermogenesis,and tissue oxidative capacity in the male Silky Starling(Sturnus sericeus)

Background: Acclimatization to winter conditions is an essential prerequisite for the survival of small birds in the northern temperate zone.Changes in photoperiod,ambient temperature and food availability trigger seasonal physiological and behavioral acclimatization in many passerines.Seasonal trends in metabolic parameters are well known in avian populations from temperate environments;however,the physiological and biochemical mechanisms underlying these trends are incompletely understood.In this study,we used an integrative approach to measure variation in the thermogenic properties of the male Silky Starling(Sturnus sericeus) at different levels or organization,from the whole organism to the biochemical.We measured body mass(Mb),basal metabolic rate(BMR),energy budget,the mass of selected internal organs,state 4 respiration and cytochrome c oxidase(COX) activity in the heart,liver and muscle.Methods: Oxygen consumption was measured using an open-circuit respirometry system.The energy intake of the birds were then determined using an oxygen bomb calorimeter.Mitochondrial state 4 respiration and COX activity in heart,liver and pectoral muscle were measured with a Clark electrode.Results: The results suggest that acclimatization to winter conditions caused significant change in each of the measured variables,specifically,increases in Mb,organ mass,BMR,energy intake and cellular enzyme activity.Furthermore,BMR was positively correlated with body mass,energy intake,the mass of selected internal organs,state 4 respiration in the heart,liver and muscle,and COX activity in the heart and muscle.Conclusions: These results suggest that the male Silky Starling's enhanced basal thermogenesis under winter conditions is achieved by making a suite of adjustments from the whole organism to the biochemical level,and provide further evidence to support the notion that small birds have high phenotypic plasticity with respect to seasonal changes.

Increased BMR in Overweight and Obese Patients with Type 2 Diabetes may Result from an Increased Fat-free Mass

The study aimed to determine the relationships between the basal metabolic rate（BMR） and body composition of overweight and obese Chinese adults with type 2 diabetes mellitus（DM）. This cross-sectional clinical study enrolled 193 Chinese adults with type 2 DM who were overweight（24 kg/m2≤BMI〈28 kg/m2, n=99）, or obese（BMI ≥28 kg/m2, n=94）. Ninety-seven adults with normal BMIs, including 50 DM patients and 47 healthy adults, were recruited as a control group. BMR was measured by indirect calorimetry; predicted BMR was calculated according to the Schofield equation; and the relationships between BMR, body composition, and biochemical results were determined by the Pearson correlation. The results showed that obese DM patients had significantly higher BMRs than both overweight patients（P〈0.05） and patients with normal BMI did（P〈0.05）. The measured BMR was significantly lower than the predicted BMR（P〈0.05） in all groups. Obese and overweight DM patients had significantly greater weight, waist circumference, hip circumference, BMI, body surface area, body fat percentage, fat mass, and fat-free mass than patients with normal BMI. Except for waist circumference, these body composition measurements were significantly increased in obese DM patients when compared with those in overweight DM patients（P〈0.05）. Fat-free mass was closely correlated with BMR in both DM patients（r=0.874, P〈0.01） and in healthy controls（r=0.902, P〈0.01）. It was concluded that overweight and obese Chinese adults with type 2 DM had increased BMRs compared with normal-weight controls, which may result from the difference in fat-free mass.

Food restriction decreases BMR,body and organ mass,and cellular energetics,in the Chinese Bulbul(Pycnonotus sinensis)

Background: Food is an important environmental factor that affects animals' energy metabolism and food shortage has significant effects on animals' behavior, physiology and biochemistry. However, to date few studies have focused on the thermogenesis and its effects on the body condition of birds. In this study, we examined the effects of food restriction on the body mass, basal metabolic rate(BMR) and body composition, and several physiological, biochemical and molecular markers potentially related to thermogenesis, in the Chinese Bulbul(Pycnonotus sinensis).Methods: Birds in the control group were provided with food ad libitum whereas those in the food restriction group were provided with one-half of the usual quantity of food for 12 days. Oxygen consumption was measured using an open-circuit respirometry system. Mitochondrial state 4 respiration and cytochrome c oxidase(COX) activity in the liver and pectoral muscle were measured with a Clark electrode. Avian uncoupling protein(avUCP) mRNA expression was determined in pectorals muscle with quantitative Real-time PCR.Results:Chinese Bulbuls in food restriction group decreased in body mass,BMR and internal organ(heart,kidneys,small intestine and total digestive tract)mass compared with the control group over the 12-day period of food restriction.Bulbuls in the food restriction group also had lower levels of state-4 respiration,COX activity in the liver and muscle,and mitochondrial avUCP gene expression in muscle compared to the control group.BMR was positively correlated with body mass,state 4 respiration in the liver and COX activity in the muscle.Conclusions:Our data indicate that Chinese Bulbuls not only sustain food shortage through simple passive mechanisms,such as reducing body and organ mass and energy expenditure,but also by reducing energetic metabolism in the liver and muscle.

藏密气功对BMR和T_3、T_4的影响

对52名藏密气功学员练功前后基础代谢率和34例甲状腺轴激素水平测定,结果显示基础代谢率有下降趋势;甲状腺轴激素中水平总 T_3下降且有显著性。

不同基础代谢率计算公式对慢性甲状腺功能亢进性肌病的诊断价值

目的:探索不同基础代谢率(BMR)公式在慢性甲状腺功能亢进性肌病(CTM)中的诊断价值。方法:选取2022年1—8月在广西医科大学第一附属医院初诊且未治疗的CTM患者46例(CTM组),同期选取年龄和性别匹配的甲亢不伴CTM患者49例(甲亢不伴CTM组)和健康体检者46例作为健康对照组。选择Gale、Reed、Read、Takeda、Kosa、Jenkins、RPP、Harris-Benedict、Cunningham等共9个BMR公式进行描述。比较各组临床资料(包括年龄、性别、体重、上臂围等)、游离三碘甲状腺原氨酸(FT_(3))、游离甲状腺激素(FT_(4))、促甲状腺激素受体抗体(TRAb)和不同公式计算下的BMR。采用受试者工作特征(ROC)曲线评估9个BMR公式对CTM的诊断效能。结果:CTM组BMR(Gale、Reed、Read、Takeda、Kosa、Jenkins、心率收缩压乘积)、FT_(3)、FT_(4)、TRAb均高于甲亢不伴CTM组、健康对照组(P<0.05)。Gale公式诊断CTM的ROC曲线下面积(AUC)为0.83(95%CI:0.74~0.91)(P<0.05),灵敏度为73.91%,特异度为81.63%,诊断CTM截断值BMR>46.00,其特异性优于Read公式法(P<0.05)。结论:用Gale公式评估的BMR对于CTM诊断有一定的参考价值。

高纤维食物对海南社鼠能量代谢的影响

自然界中食物质量常存在季节性变化,可影响小型哺乳动物的生理特征及其生存和分布。为研究高纤维(低质量)食物对栖息于贵州遵义的海南社鼠(Niviventer lotipes)能量代谢的影响,通过饲喂标准兔饲料(高纤维)或鼠饲料(低纤维)处理海南社鼠4周,实验期间测定动物的体重和能量摄入,使用开放式代谢仪测定动物的能量消耗,并在实验处理结束后解剖动物进行身体成分分析。研究发现,饲喂兔饲料的海南社鼠实验期间体重持续下降,到实验结束时为饲喂鼠饲料动物(对照组)体重的62.8%。饲喂兔饲料4周后,动物的整体基础代谢率和非颤抖性产热显著下降,分别为对照组的55.1%和63.4%。饲喂兔饲料的海南社鼠干物质摄入、消化能和消化率显著降低,分别为对照组的63.7%、38.8%和71.8%;身体成分分析显示,主要内脏器官重量以及消化道的重量和长度也显著下降。研究结果表明,饲喂高纤维的兔饲料后海南社鼠没有增加食物摄入来补偿消化率的下降,消化道形态尤其是小肠和盲肠的重量和长度没有适应性增加,虽然动物可通过降低基础代谢率和非颤抖性产热节约能量,但动物能量利用效率太低不能维持能量平衡而体重显著下降,海南社鼠对高纤维食物较差的适应性,可能与其在亚热带分布对高纤维食物利用的选择压力较小有关。

东北地区黑线仓鼠的代谢产热特征及其体温调节

为探讨寒冷地区黑线仓鼠 (Cricetulusbarabensis)的代谢产热特征及体温调节 ,本文采用封闭式流体压力呼吸仪对其代谢率、热传导和体温等热生物学指标进行了测定。结果显示 :在环境温度为 5～ 35℃的范围内 ,黑线仓鼠的体温基本维持恒定 ,平均体温为 36 33± 0 2 3℃ ;热中性区为 2 5～ 32 5℃ ;基础代谢率为 3 4 9±0 36mlO2 / (g·h) ;环境温度 (Ta)在 5～ 2 5℃范围内 ,代谢率 (MR)与Ta 呈负相关 ,回归方程为 :MR [mlO2 / (g·h) ]=9 6 0 - 0 2 2Ta (℃ ) ,在此范围内 ,黑线仓鼠的热传导率 (C)最低 ,平均为 0 2 8± 0 0 1mlO2 /(g·h·℃ ) ;代谢预期比和热传导预期比 (F值 )为 1 6 8。黑线仓鼠的基本热生物学特征为 :较高的BMR和热传导率 ,相对较低的体温和较宽的热中性区。这些特征可能限制了其在极端寒冷和干旱环境中的分布和生存.

华北农田大仓鼠的能量代谢特征及其体温调节

利用封闭式流体压力呼吸计 ,测定了华北农田主要害鼠大仓鼠 (CricetulustritondeWinton)在 5～36℃范围内的能量代谢特征。结果表明 :在 5～ 31℃范围内 ,大仓鼠的体温基本维持恒定 ,平均体温为 (36 7±0 1)℃ ;热中性区为 2 9～ 34℃ ;基础代谢率 (BMR)为 (1 2 3± 0 0 2 )mLO2 /(g·h)。在 5～ 15℃范围内 ,热传导率维持恒定 ,平均为 (0 12± 0 0 0 )mLO2 /(g·h·℃ )。大仓鼠的能量代谢特征是 :在总兽类中 ,高于期望值 ;在啮齿动物中 ,低于期望值 ;在仓鼠亚科动物中 ,稍高于期望值 ;从食性上看 ,高于食种子类的期望值 ,而与食草类的期望值相似 ;体温稍低 ;热传导较高 ;这些特征与该物种夜行性、主要以作物的种子为食、独居和穴居等生活习性密切相关。结合大仓鼠在我国主要分布于长江以北 ,但在极端干旱和高寒地区则没有分布的特点 ,提出了生理生态特征可能是限制大仓鼠地理分布的重要因素的观点。