高寒矮嵩草草甸两种主要植物耐牧性的比较

通过野外控制实验,研究了刈割(留茬3 cm、留茬1 cm及不刈割)、施肥(施肥、不施肥)和浇水(浇水、不浇水)处理对高寒草甸矮嵩草(Kobresia humilis)和垂穗披碱草(Elymus nutans)补偿高度、株高相对生长率、比叶面积、叶片净光合速率和地上总生物量的影响.结果表明:2物种的株高和地上总生物量在刈割后均为低补偿响应,但其株高相对生长率显著提高,并均随年份而增加;垂穗披碱草比叶面积、叶片净光合速率和地上总生物量对刈割损伤更加敏感;尽管施肥能显著提高2物种上述各项指标,但在不同处理条件下矮嵩草的耐牧性指数均小于垂穗披碱草;浇水的作用不显著.说明2物种的耐牧性依赖于土壤养分资源获得性,矮嵩草的耐牧性强于垂穗披碱草.     

刈割、施肥和浇水对矮嵩草补偿生长的影响

通过对青海海北高寒矮嵩草(Kobresia humilis)草甸进行为期3年的野外控制试验, 研究了刈割(留茬1 cm、3 cm及不刈割)、施肥(2.5 g·m^-2尿素+ 0.6 g·m^-2磷酸二胺、不施肥)和浇水(20.1 kg·m^-2、不浇水)处理对矮嵩草补偿生长(包括分株密度、株高和分株地上生物量)的影响, 及其比叶面积、叶片净光合速率和相对增长率的变化, 探讨矮嵩草补偿生长的机制。研究结果表明: 刈割后, 矮嵩草的补偿生长高度和比叶面积显著降低; 分株密度有增加的趋势, 但会随刈割强度的增加而下降; 株高和生物量的相对增长率随刈割强度的增加而呈上升趋势; 补偿地上生物量在重度刈割处理下最高。施肥能显著增加矮嵩草的补偿高度、分株密度、补偿地上生物量、株高相对增长率、生物量相对增长率、比叶面积和净光合速率; 与不浇水处理相比, 浇水处理对重度刈割处理下的分株地上生物量、密度相对增长率、比叶面积和净光合速率无影响, 而显著降低了中度刈割处理下的补偿高度和株高相对增长率, 提高了不刈割处理下的分株密度和重度刈割处理下的生物量相对增长率。刈割、施肥和浇水处理的交互作用也显示出刈割与施肥对矮嵩草补偿生长具有拮抗效应, 而刈割与浇水具有协同效应。上述结果说明, 矮嵩草在刈割后可通过增加分株密度和相对增长率等途径来提高补偿能力, 弥补在生长高度上出现的低补偿, 而施肥可显著抵消刈割的不利影响, 提高矮嵩草的补偿能力。     

种群密度与施肥对垂穗披碱草刈割后补偿作用的影响

 以甘南亚高山草甸常见牧草垂穗披碱草(Elymus nutans)为对象,通过考察种群密度、施肥与刈割处理等对植物生长和生殖的影响效应,比较了垂穗披碱草在5个密度及2个施肥实验处理条件下对4种刈割处理的补偿性反应特点。结果表明,在所有密度及施肥处理条件下,早期轻度刈割处理 (分蘖期刈割,留茬4 cm) 都有利于植物的补偿作用,后期重度处理 (拔节期刈割,留茬2 cm) 可显著降低植物的地上部分生物量及生殖部分干重 (穗重)。在不施肥情况下,刈割对垂穗披碱草的影响程度随种群密度而加大,在低密度处理中早期轻度刈割的植物发生了超补偿。可以认为,低密度种群中植物具有较多的分蘖是植物在刈割后表现出较高补偿能力的一个重要生物学原因。实验还发现,施肥可提高植物个体的分蘖能力和秆叶再生能力,因而总体上可增强植物的补偿能力,并且在中等密度条件下垂穗披碱草的补偿能力较强,尽管没有发生超补偿现象。不过,施肥主要是有利于植物地上营养器官的补偿,生殖器官的补偿程度较小一些。试验结果对科学管理人工草场具有一定的指导意义。     

光照，施肥及刈割对垂穗披碱草生长的影响

以甘南高寒草甸常见牧草垂穗披碱草（Elymus nutans）为研究对象,比较不同光照、肥力条件下,垂穗披碱草对刈割的生长和补偿反应。研究发现,光照和肥力存在交互作用。施肥、中度光照下,未刈割单株垂穗披碱草地上生物量最大,为3．239g。施肥、中度光照下,比较刈割植株地上生物量补偿发现：晚期刈割单株地上生物量的补偿大于早期刈割;刈割强度无显著影响;刈割两次单株地上生物量的补偿最大。施肥、中度光照、晚期、轻度、一次刈割时,单株垂穗披碱草地上生物量累积最大,为4．500g。全光照、未施肥条件下,刈割对单株地上生物量的补偿无影响。就补偿机制而言,植株地上生物量的增加以地下生物量为代价。     

施肥和刈割对垂穗披碱草（Elymus nutans）、中华羊茅（Festuca sinensis）和羊茅（Festuca ovina）种间竞争力的影响

试验选用青藏高原东部高寒草甸普遍存在的3种禾本科牧草垂穗披碱草(Elymus nutans)、中华羊茅(Festuca sinensis)以及羊茅(Festuca ovina)进行种间竞争的野外研究.通过测定3种牧草生物量的干重,对其进行方差分析并计算了相对产量总和(RYT)以及竞争率(CR).结果如下:对实验物种竞争率(CR)的分析表明垂穗披碱草的竞争力最强,中华羊茅次之,羊茅最差.施肥和刈割处理对于原来的竞争格局没有影响,即在施肥、刈割及其交互作用下3种牧草的竞争等级均是一致的.对试验物种混播的相对产量总和(RYT)的分析表明:在中华羊茅与垂穗披碱草的混播中,两种组成物种利用相同的资源,表现出相互竞争的趋势,这种趋势是非密度依赖的;垂穗披碱草和羊茅混播,在低密度时,羊茅和垂穗披硷草可以共享资源,但是随着密度增加,羊茅和垂穗披碱草表现出竞争相同资源的趋势;在中华羊茅和羊茅的混播中,二者在生长过程中能够共享资源,有相互促进的趋势,表现出共生的关系,且是非密度依赖的.     

光照强度和肥力变化对垂穗披碱草生长的影响

在野外条件下,采用析因设计,对光照和肥力变化影响下垂穗披碱草的生长参数进行测定,评估垂穗披碱草对异质环境的适应特性。光照分为高光照(100%光照强度)、中度光照(43.5%光照强度)与低光照(6.74%光照强度);肥力分为施肥与不施肥。结果表明,垂穗披碱草在光照强度由高光照(100%)向中度光照(43.5%)变化情况下,地上生物量、分蘖数无变化,株高增大,光照强度减小到6.74%时,地上生物量、分蘖数、株高均减小。比叶面积(SLA)随光照强度的减弱而增加,相对生长率(RGR)随光照强度的减弱而减小,施肥对SLA和RGR无影响。根冠比在中度光照和低光照下各处理之间差异均不显著,高光照(100%)下增加肥力,根冠比增大。施肥时,叶分配随光照强度的减弱而增加,繁殖分配减小,不施肥时,叶分配与繁殖分配在高光照(100%)和中度光照(43.5%)下无差异,低光照(6.74%)下,叶分配增大,繁殖分配减小。施肥时茎分配在中度光照强度(43.5%)下最大,高光照强度(100%)下次之,低光照强度(6.74%)下最小,不施肥时,茎分配在高光照(100%)和中度光照(43.5%)下无差异,低光照(6.74%)下减小。研究表明:垂穗披碱草是一个光照耐受型物种,光照强度减小到全光照一半时仍可正常生长。在低光环境中,垂穗披碱草通过增加株高和大而薄的叶片,来适应环境,资源主要在叶分配、茎分配、繁殖分配之间进行了权衡。     

氮硅添加对高寒草甸垂穗披碱草叶片全氮含量及净光合速率的影响

该文以青藏高原高寒草甸优势种垂穗披碱草(Elymus nutans)为研究对象, 探究不同水平氮肥与硅肥混合添加后对其叶片全氮含量和净光合速率的影响, 以期对高寒草甸牧场施肥提供一定的理论依据。研究发现: 氮、硅单独添加时, 均可提高垂穗披碱草叶片全氮含量以及净光合速率; 氮、硅配施处理对叶片全氮含量和净光合速率均存在显著的交互作用; 低(N₁)、中(N₂)、高(N₃) 3种不同浓度的氮肥处理下, 低硅(Si₁)添加对垂穗披碱草叶片全氮含量以及净光合速率没有显著的促进作用, 而添加中浓度硅肥(Si₂)可显著提高垂穗披碱草叶片全氮含量; 低、中浓度施氮水平下, 中浓度硅肥可显著促进垂穗披碱草光合作用; 叶片全氮含量和净光合速率最大平均值均出现在中浓度氮、硅肥配施下, 与不施肥相比分别提高了119.99%和85.70%; 就该试验而言, 施加氮肥的同时, 适当添加一些硅肥能够更好地提高垂穗披碱草叶片全氮含量和净光合速率, 且硅的添加量为8 g·m^-2时效果较好。     

施肥和刈割对冷地早熟禾补偿生长的影响

以青藏高原东部高寒草甸常见牧草冷地早熟禾(Poa crymophila)为研究对象,比较研究了肥力和不同刈割处理对植物生长和生物量补偿的影响。实验采用随机设计,肥力分为施肥和不施肥,刈割处理为刈割时间、刈割频度和刈割强度3因子组合。结果表明:不刈割情况下,施肥显著促进冷地早熟禾的生长,而在刈割情况下,施肥对植物的生长没有明显的促进作用甚至有负作用。不施肥,刈割可促进冷地早熟禾地上生物量的增加并发生超补偿,但补偿程度因刈割强度、刈割频度和刈割时间而异;施肥时,刈割没有或很少促进植株发生超补偿。超补偿发生时,资源贫瘠的条件可能是必需的。冷地早熟禾发生超补偿可能是以损耗地下部分的资源为代价的,刈割刺激分蘖的增加对超补偿的发生也有一定的贡献。     

植株密度和氮素互作对垂穗披碱草生物量分配的影响

垂穗披碱草（Elymus nutans）是高寒地区建植和改良栽培草地的首选草种。虽然合理植株密度和氮素添加量是垂穗披碱草栽培草地稳产的关键因子,但两者之间是否存在最佳互作组合仍不清楚。采用盆栽试验,通过分析不同植株密度（58、102、146株/m²）和氮素添加量（0、200、400 mg/kg）组合状态下垂穗披碱草株高、单株分蘖数、地上生物量、地下生物量、根系体积和地上地下生物量比,以确定理论上是否存在植株密度和氮素添加量的最佳组合。结果表明：随植株密度增加,垂穗披碱草株高、地上生物量和地上地下生物量比值均先增加后降低,而单株分蘖数逐渐减小,根系体积和地下生物量先增加后保持相对稳定;随氮素添加量增加,垂穗披碱草单株分蘖数、地上生物量和地上地下生物量比值均表现为先增加后降低,地下生物量逐渐降低。植株密度与氮素添加量互作虽然对垂穗披碱草的根系体积和单株分蘖数没有显著影响,但两者互作显著影响了垂穗披碱草株高、地上生物量、地下生物量、地上地下生物量比（P<0.01）,这些指标与植株密度和氮素添加量的关系均表现为一个开口向下的抛物面。当植株密度为102株/m²和氮素添加量为200 mg/kg时,垂穗披碱草栽培草地产量最大,生物量分配最优。垂穗披碱草植株密度和氮素添加互作时理论上存在最佳组合,这为垂穗披碱草栽培草地的田间管理提供了理论依据。     

不同处理对藏北地区退化人工草地垂穗披碱草种群克隆表型的影响

以不同退化程度和采用不同恢复措施的垂穗披碱草人工草地为对象,通过野外调查和室内分析相结合的方法研究了各类草地垂穗披碱草克隆种群相关表型特征的差异,结果表明,随着人工草地建植年限的延长,草地退化渐趋严重,垂穗披碱草克隆种群相关表型参数显著降低.相比较而言,封育可以提高种群的有性繁殖能力,但施肥和补播措施可以显著提高垂穗披碱草种群的克隆生长,其株高、分株数以及株丛数显著增加,而有性繁殖能力相对降低.因此,针对藏北高原以垂穗披碱草为最主要建群种或单优种群的退化草地恢复,施肥和补播应为最有效措施.     

Physiological effects of compensatory growth during the larval stage of the ladybird,Cryptolaemus montrouzieri

The growth rate of insects may vary in response to shifty environments. They may achieve compensatory growth after a period of food restriction followed by ad libitum food, which may further affect the reproductive performance and lifespan of the resulting phenotypes. However, little is known about the physiological mechanisms associated with such growth acceleration in insects. The present study examined the metabolic rate, the antioxidant enzyme activity and the gene expression of adult Cryptolaemus montrouzieri (Coleoptera: Coccinellidae) after experiencing compensatory growth during its larval stages. Starved C. montrouzieri individuals achieved a similar developmental time and adult body mass as those supplied with ad libitum food during their entire larval stage, indicating that compensatory growth occurred as a result of the switch in larval food regime. Further, the compensatory growth was found to exert effects on the physiological functions of C. montrouzieri, in terms of its metabolic rates and enzyme activities. The adults undergoing compensatory growth were characterized by a higher metabolic rate, a lower activity of the antioxidant enzymes glutathione reductase, catalase, and superoxide dismutase and a lower gene expression of P450 and trehalase. Taken together, the results indicate that although compensatory growth following food restriction in early larval life prevents developmental delay and body mass loss, the resulting adults may encounter physiological challenges affecting their fitness.     

Effect or ractopamine on growth and body composition of pigs during compensatory growth

The purpose of this study was to measure the growth and body composition of pigs during normal or compensatory growth from 60 to 100 kg, without (cont) or with ractopamine (rac) supplementation (20 mg/kg of diet). Thirty-four pigs were scanned by dual X-ray absorptiometry (DXA) for body composition analysis at a starting weight of 61.4 ± 0.3 kg and at a final weight of 100.4 ± 0.5 kg. Half the pigs were fed ad libitum throughout (8 cont and 9 rac). The other half were fed at maintenance for 8 weeks and then scanned again by DXA. Following the maintenance feeding, the pigs were fed ad libitum (9 cont and 8 rac) to the final weight. Compensatory growth resulted in a 30% increase in the rate of weight gain (1.23 v. 0.94 kg/day, P < 0.05), including a 44% increase in the rate of lean tissue deposition (0.90 v. 0.62 kg/day, P < 0.05), but no change in the rate of fat deposition (0.31 v. 0.30 kg/day, P > 0.05). Feeding rac resulted in a 13% increase in the rate of weight gain (1.15 v. 1.02 kg/day, P < 0.05), consisting of a 29% increase in the rate of lean tissue deposition (0.86 v. 0.67 kg/day, P < 0.05) and an 18% reduction in the rate of fat deposition (0.27 v. 0.33 kg/day, P < 0.05). The effects of ractopamine on the rates of fat and lean tissue deposition were similar for pigs continuously fed ad libitum and those experiencing compensatory growth. Both compensatory growth and the addition of ractopamine to the diet resulted in an improvement in efficiency of protein deposition; however, ractopamine also resulted in a reduction in the efficiency of energy deposition. For both growth rate and lean tissue deposition, there was an additive effect for ractopamine and compensatory growth. Thus, feeding ractopamine will enhance the growth and body composition during compensatory growth in swine.     

Validation and implications of a growth model for brown trout, Salmo trutta, using long-term data from a small stream in north-west England

Summary 1. The objectives were: (i) to check the validity of a new growth model; (ii) to examine the relationship between population density and both mean mass and mean growth rate and (iii) to discover if compensatory growth occurred. First (0+) and second (1+) year‐old juvenile sea‐trout were sampled by electrofishing at the beginning and end of the summer from 1967 to 2000. Additional samples were taken in some years in winter and in the critical period for survival when the fry first emerge from the gravel. The trout left the stream as pre‐smolts in May, soon after their second birthday. 2. A growth model ( Elliott, Hurley & Fryer, 1995 ) estimated the mean mass of the trout over the 2 years spent in fresh water. The date and mean mass at the start of the growth period were defined as the median date for fry emerging from the gravel and their mean mass at emergence, both being estimated from individual‐based models ( Elliott & Hurley, 1998a, b ). 3. The variation in mean mass among year‐classes was small for newly‐emerged fry (CV = 6.2%), maximum at the start of the first summer of the life cycle (CV = 38.1%), and then decreased gradually for successive life‐stages to a low value for pre‐smolts (CV = 10.8%). Mean mass was not related to population density and, therefore, mean growth rate was density‐independent. Growth in the first, but not the second, winter of the life cycle was lower than model prediction, but when it was assumed in the model that there was no first‐winter growth, there was good agreement in most year‐classes between model estimated values and observed mean mass. Exceptions were that mean masses and growth rates for 0+ trout after four summer droughts were lower than expected, but compensatory growth followed, so that observed and expected masses were similar for 1+ trout. 4. Pre‐smolt mean mass on 30 April measured total growth achieved in the freshwater phase of the life cycle. This was significantly related to mean mass at the end of the first and second summers of the life cycle, but not to the emergence date and mean mass of emerging fry. 5. These juvenile sea‐trout were growing at their maximum potential in most year‐classes but when this was not achieved, compensatory growth soon restored their mass to values expected from the model. This ensured a low variation in the mean mass of pre‐smolts just before they migrated to the sea. However, the latter mass was higher in more recent year‐classes (1987–98) than in previous ones (1967–86), demonstrating the effect of slightly higher stream temperature. This study has shown the importance of developing realistic growth models in order to detect departure from maximum potential growth, and the more subtle effects of temperature change, possibly due to the effects of climate change.     

Source populations in carnivore management: cougar demography and emigration in a lightly hunted population

Wildlife agencies typically attempt to manage carnivore numbers in localized game management units through hunting, and do not always consider the potential influences of immigration and emigration on the outcome of those hunting practices. However, such a closed population structure may not be an appropriate model for management of carnivore populations where immigration and emigration are important population parameters. The closed population hypothesis predicts that high hunting mortality will reduce numbers and densities of carnivores and that low hunting mortality will increase numbers and densities. By contrast, the open population hypothesis predicts that high hunting mortality may not reduce carnivore densities because of compensatory immigration, and low hunting mortality may not result in more carnivores because of compensatory emigration. Previous research supported the open population hypothesis with high immigration rates in a heavily hunted (hunting mortality rate=0.24) cougar population in northern Washington. We test the open population hypothesis and high emigration rates in a lightly hunted (hunting mortality rate=0.11) cougar population in central Washington by monitoring demography from 2002 to 2007. We used a dual sex survival/fecundity Leslie matrix to estimate closed population growth and annual census counts to estimate open population growth. The observed open population growth rate of 0.98 was lower than the closed survival/fecundity growth rates of 1.13 (deterministic) and 1.10 (stochastic), and suggests a 12–15% annual emigration rate. Our data support the open population hypothesis for lightly hunted populations of carnivores. Low hunting mortality did not result in increased numbers and densities of cougars, as commonly believed because of compensatory emigration.     

Impact of flow velocity on the dynamic behaviour of biofilm bacteria

Abstract

The impact of flow velocity (FV) on the growth dynamics of biofilms and bulk water heterotrophic plate count (HPC) bacteria in drinking water distribution systems was quantified and modeled by combining a logistic growth model with mass balance equations. The dynamic variations in the specific growth and release rates of biofilm bacteria were also quantified. The experimental results showed that the maximum biofilm biomass did not change when flow velocity was increased from 20 to 40 cm s^?1, but was significantly affected when flow velocity was further increased to 60 cm s^?1. Although the concentration of biofilm bacteria was substantially reduced by the higher shear stress, the concentration of bacteria in the bulk fluid was slightly increased. From this it is estimated that the specific growth rate and specific release rate of biofilm bacteria had doubled. The specific release (detachment) rate was dependent on the specific growth rate of the biofilm bacteria.     

饥饿和再投喂对虎斑乌贼幼体存活、生长和消化酶活力的影响

本文探究了饥饿胁迫与饥饿后再投喂对虎斑乌贼幼体存活率、生长、行为、肝体比、摄食率以及消化酶活力的影响.在室内控制条件下开展了幼体(初始体质量为4.95±0.48 g)的饥饿(0、1、2、3、4、5、6 d)和再投喂(15 d)试验.结果表明: 不同饥饿时间对虎斑乌贼的幼体存活率、体质量降低率、肝体比和消化酶活力影响显著.随着饥饿胁迫时间的增加,其存活率、肝体比呈下降趋势,其中饥饿3 d后,存活率开始明显下降,体质量降低率明显增大,幼体出现喷墨、互相残杀等异常行为;4种消化酶活力呈先下降后上升的趋势,淀粉酶活力以饥饿4 d组最低 (0.07±0.02 U·mg^-1·prot^-1);脂肪酶活力以饥饿2 d组最低(18.47±2.07 U·g^-1·prot^-1),饥饿6 d组最高(57.60±3.98 U·g^-1·prot^-1),胃蛋白酶活力和胰蛋白酶活力以饥饿5 d组(1.98±0.59 U·mg^-1·prot^-1)和饥饿4 d(186.68±20.72 U·mg^-1·prot^-1) 最低.饥饿处理结束后,经15 d再投喂,各试验组存活率、特定生长率、肝体比和摄食率差异显著,幼体的存活率、特定生长率、肝体比和摄食率均与饥饿处理时间呈负相关;饥饿1和2 d组与对照组的存活率、特定生长率和肝肝体比无显著差异,而饥饿3～6 d组显著低于对照组;饥饿1～2 d组的摄食率明显高于对照组,而饥饿6 d组的摄食率明显小于对照组;各组淀粉酶与脂肪酶活力无显著差异,胃蛋白酶与胰蛋白酶活力差异显著,均以对照组最高(胃蛋白酶活力7.06±0.64 U·mg^-1·prot^-1,胰蛋白酶活力914.67±26.54 U·mg^-1·prot^-1),饥饿6 d组最低(胃蛋白酶活力3.21±0.57 U·mg^-1·prot^-1,胰蛋白酶活力660.04±37.92 U·mg^-1·prot^-1).说明虎斑乌贼的幼体饥饿不可逆点(PNR)为第6天,且不能补偿生长.     

鼎湖山南亚热带常绿阔叶林荷木种群动态变化

荷木(Schima superba)是鼎湖山南亚热带常绿阔叶林群落中的优势种,为了解南亚热带常绿阔叶林的群落构建机制,该研究分析了鼎湖山南亚热带常绿阔叶林20 hm2样地中荷木种群在2005—2017年间的动态变化,并从径级和生境两个方面分析了其死亡率的分布特征。结果表明:(1)荷木种群个体数量从2005—2017年呈现出减少的态势。(2)在径级方面,荷木的死亡率和相对生长率的变化在不同径级区间呈现出不同的变化规律。径级在1～10 cm范围的荷木相对生长率大并迅速下降,死亡率上升且维持在较高水平;径级在10～50 cm范围的荷木随着径级增大,相对生长率减缓,然后下降,而死亡率不断下降;在50 cm以上的径级范围内,荷木相对生长率小、死亡率大。(3)不同生境中,2010年各个生境死亡率相差不大,2015年高海拔生境(高坡、山脊、高谷)死亡率大于低海拔生境(低坡、低谷),2017年则为低海拔生境大于高海拔生境。(4)荷木的死亡率与土壤中酸碱度呈正相关关系,而与土壤有机质、总氮、总磷、有效钾、有效氮含量呈负相关关系。     

Effect of restricted feeding and realimentation periods on compensatory growth performance and physiological characteristics of pigs

An experiment with 94 growing pigs was conducted to determine the effect of a feed restriction of 25% on performance, carcass quality, organ weight, blood hormone levels and some biochemical parameters. The experiment consisted of four periods of 21 days each. In the different periods animals (initial BW about 31 kg) were fed ad libitum (A) or restrictively (R), resulting at day 84 in Groups AAAA, AARA, RAAA and RARA. During Period I, the daily gain of restrictively fed pigs (Group R) was about 22% lower than from Group A (p < 0.01). During realimentation, compensatory growth was observed in Period II for Group RA, and in Period IV for Group RARA. No compensatory growth was observed for Group AARA, which was fed restrictively in Period III only (day 43 to 63). For the whole experiment (day 1 to 84), BW gain and feed conversion amounted to 830 g/d and 3.03 kg/kg, 798 g/d and 2.99 kg/kg, 813 g/d and 2.86 kg/kg, and 800 g/d and 2.78 kg/kg for Groups AAAA, AARA, RAAA and RARA, respectively. The decrease of liver and kidney weights as a result of restricted feeding was not significant and after three weeks of realimentation these differences almost disappeared. At day 3 after realimentation of restrictively fed pigs (Group RA) the growth hormone level was significantly increased, but at day 14 of realimentation this level turned out to be lower (p < 0.01) than in pigs fed ad libitum (Group AA). This was considered as a further indication of compensatory growth.