Effect of a novel consensus bacterial 6-phytase variant in grower pigs fed corn-soybean meal-based diets formulated with a full nutrient matrix and no added inorganic phosphorus

The capacity of a novel consensus bacterial 6-phytase variant (PhyG) to entirely replace dietary inorganic phosphorus (Pi) source in grower pigs fed diets with reduction of calcium (Ca), net energy (NE), and digestible amino acids (AA) was evaluated, using growth performance and apparent total tract digestibility (ATTD) of nutrients as outcome measures. A total of 352 mixed-sex pigs (initial BW 23.4 kg) were randomized to 4 treatments, 8 pigs/pen, and 11 pens/treatment. Diets were corn-soybean meal-based and formulated by phase (grower 1, 25 to 50 and grower 2, 50 to 75 kg BW). The positive control diet (PC) provided adequate nutrients and a negative control diet (NC) was formulated without Pi (1.2 g/kg ATTD P) and reduced in Ca (-0.12 to -0.13 percentage points), NE (-32 kcal/kg), and digestible essential AA (-0.004 to -0.026 percentage points) vs. PC. Two further treatments comprised the NC plus 500 or 1,000 FTU/kg of PhyG. Data were analyzed by ANOVA, mean contrasts and orthogonal polynomial regression. Nutrient reductions in the NC reduced (P < 0.05) average daily gain (ADG) during grower 1 and overall (73 to 136 d of age), increased (P < 0.05) feed conversion ratio (FCR) during grower 1 and overall and tended to reduce (P < 0.1) average daily feed intake (ADFI) during grower 2 and overall, vs. PC. Phytase supplementation improved (P < 0.05) FCR during grower 1, ADG during grower 2 and overall, ATTD of DM and P, and tended to improve DE (P = 0.053) in a linear dose-dependent manner. PhyG at 1,000 FTU/kg resulted in growth performance (all measures, all phases) equivalent to PC. The findings demonstrate that PhyG at 1,000 FTU/kg totally replaced Pi in complex grower pig diets containing industrial co-products, compensated a full nutrient matrix reduction and maintained performance.     

Effect of piglet birth weight on body weight,growth, backfat,and longissimus muscle area of commercial market swine

The objective of this study was to estimate the effect of piglet birth weight on future BW, growth, backfat, and longissimus muscle area of pigs in a commercial U.S. production system. Pigs (n = 5727) at a commercial farm were individually weighed and identified within 24 h of birth. Weights were collected prior to weaning (n = 4108), after finisher placement (n = 3439), and 7 (n = 1622) and 16 (n = 1586) weeks into finishing; hot carcass weight was also collected (n = 1693). Average daily gain during lactation, nursery, finishing, and overall (birth to 16 weeks into finishing) was calculated. During BW collection 16 weeks into finishing, real-time ultrasound backfat thickness and longissimus muscle area were measured. Sex × birth weight (linear and quadratic) interactions were observed for BW at weaning and finisher placement and daily gain during pre-weaning and nursery. Linear birth weight × cross foster interactions were observed for weaning weight and pre-weaning gain. Linear and quadratic effects of birth weight on BW at weaning, finisher placement, 7 and 16 weeks into finishing, and hot carcass weight and average daily gain during pre-weaning, nursery, finishing, and total were observed. For all measures of BW and average daily gain, as birth weight increased subsequent BW and average daily gain increased at a decreasing rate; however, for the sex × birth weight (linear and quadratic) interactions, heavier birth weight barrows were lighter and grew slower than gilts of comparable birth weight. Worth noting, the birth weight × sex interactions described very few pigs in the extreme portion of the birth weight distribution. For birth weight × cross foster interactions, non-cross fostered pigs were increasingly heavier and faster growing as birth weight increased compared to cross fostered pigs. Heavier birth weight pigs tended to have increased backfat depth (P = 0.07). Linear and quadratic effects of birth weight on longissimus muscle area were observed; as birth weight increased muscling increased at a decreasing rate. Regardless of interactions or period of production, increased birth weight resulted in heavier future BW, faster daily gain along with larger longissimus muscle area prior to harvest. In all instances the magnitude of the negative effect of birth weight increased as birth weight decreased.     

丝氨酸的生理功能及其在猪生产中的应用研究进展

丝氨酸可通过内源性途径合成,在传统营养学上属于非必需氨基酸.在机体正常生理功能下,丝氨酸广泛参与嘌呤合成、一碳代谢、谷胱甘肽合成以及脂质合成等多个重要的机体代谢过程.此外,丝氨酸还对细胞增殖分化、氧化还原平衡、神经系统和免疫功能等具有调节作用.近期研究发现,丝氨酸有益于肠道健康,且可提高猪的生长性能.本文主要综述了丝氨...     

Growth performance and metabolic responses in barrows fed low-protein diets supplemented with essential amino acids

This study was conducted to determine the effect of supplementation with Lys, Met, Thr to low-protein diets on growth performance and metabolic responses in growing barrows. Seventy crossbred barrows (Duroc × Yorkshine), with an average initial body weight of 16 kg, were fed diets containing five crude protein (CP) levels (18.2, 16.5, 15.5, 14.5, and 13.6%) and 0.83% true ileal digestible lysine. On d 17 of the trial, all pigs were fitted with an indwelling jugular catheter for blood collection. On d 18 and 53, blood samples were obtained at 4 h post feeding. Reducing dietary CP concentration linearly decreased (P < 0.05) ADG, ADFI, feed efficiency, longissimus muscle area (LMA), and plasma concentrations of urea N and protein, while increasing backfat thickness linearly (P < 0.05). Pigs fed the 13.6% CP diet exhibited the poorest growth performance. On d 53, dietary CP affected plasma IGF-I (quadratic, P < 0.01) and leptin (linear, P < 0.01) concentrations. Plasma leptin levels were correlated positively with backfat thickness (r = 0.76, P < 0.05) and negatively with LMA (r = − 0.64, P < 0.01). There was a positive correlation between ADG and plasma IGF-I concentrations (r = 0.91, P < 0.05). Our results suggest that adequate provision of nonessential AA and all EAA is required for achieving maximum growth performance and reducing fat accretion in growing pigs fed low-CP diets.     

乌金猪日粮能量水平对生长性能和胴体品质的影响

本文旨在研究日粮不同能量水平对乌金猪生长性能及胴体品质的影响,采用模糊综合评定系统分析确定最佳生长性能和胴体品质所需的日粮适宜能量水平.试验采用单因子随机分组设计,选取体重15 kg左右的乌金猪90头,随机分为5组,每组18头.日粮能量水平分别为14.22、13.60、12.98、12.36和11.74 MJ/kg.结果表明,随日粮能量水平的降低,不同生长阶段的日增重逐渐降低,料重比逐渐升高,15～30 kg阶段日增重无显著差异(P>0.05).在60和100 kg体重时随日粮能量水平的降低,瘦肉重、瘦肉率和眼肌面积增加,脂肪重、脂肪率和背膘厚降低.通过拟合曲线确定15～30 kg、30～60 kg和60～100 kg阶段最佳生长性能所需的日粮适宜能量水平分别为14.01、13.15和12.98 MJ/kg.确定15～30 kg、30～60 kg和60～100 kg阶段时获得最优胴体品质时,适宜的日粮能量水平分别为11.13、11.36和11.71 MJ/kg.综合评定生长性能和胴体品质,15～30 kg、30～60 kg和60～100 kg阶段,乌金猪获得最佳生长性能的胴体品质的日粮适宜能量水平分别为13.55、12.81和13.20 MJ/kg.研究结果为乌金猪的合理饲养提供科学依据.     

Evaluation of immune system function in neonatal pigs born vaginally or by Cesarean section

Full term crossbred sows were selected to study the interaction of the immune system, hypothalamus-pituitary-adrenal axis, and growth in pigs born by Cesarean section (c-section; n=4 sows) or vaginal birth (n=4 sows). Gestation length and birth weight did not differ between vaginal birth and c-section pigs (P=0.34 and 0.62, respectively). Blood and tissue samples were collected from 44 pigs at birth. Forty-five pigs were weaned at 13 d. On d 14, pigs received an i.p. injection of lipopolysaccaride (LPS; 150 microg/kg) or saline at min 0, and blood samples were collected at -20, -10, 0, 5, 10, 20, 40, 60, 90, and 120 min. Vaginal birth pigs had 21% greater average daily gain than c-section pigs on d 14 (P<0.01). Basal serum concentrations of adrenocorticotrophin (ACTH) and cortisol were greater in c-section than vaginal birth pigs at birth (P<0.01) but were not different at 14 d (P=0.99 and 0.80, respectively). LPS increased serum concentrations of ACTH, cortisol, interferon-gamma (IFN-gamma), and tumor necrosis factor-alpha (TNF-alpha; P<0.01) but the response was not different between c-section and vaginal birth (P>0.22). Basal serum concentrations of TNF-alpha tended to be greater in c-section vs vaginal birth pigs at 14 d (P=0.0967); however, basal serum concentrations of IFN-gamma tended to be lower in c-section pigs vs vaginal birth pigs at 14 d (P=0.0787). Expression of interleukin (IL)-6, IL-6 receptor, IL-1beta, and TNF-alpha mRNA did not differ between vaginal birth and c-section pigs but changed in an age and tissue dependent manner. Thus, reduced growth rate of c-section pigs is associated with altered immune system function.     

A survey of bone integrity from cull sows in Ireland

The objective of this study was to examine the differences in sow metacarpal properties through various parities and to compare the incidence of locomotory problems between stalled and loose-housed sows. Metacarpals (n = 110) of sows from six farms were collected at slaughter and stored at -20°C. Bones from one forelimb of sows in stalls (n = 36) and loose-housed (n = 20) were collected and their articular surfaces examined for Osteochondrosis Dissecans (OCD), these sows were also scored for lameness pre-slaughter. Metacarpals were CT scanned for cross sectional area and moment of inertia. Cylindrical sections from the diaphysis were used for mechanical testing and calculating bone strength indices. The results show there was little change in bone mineral status throughout the range of parities examined and overall metacarpal integrity was not compromised by multiple production cycles. There were no differences detected in the incidence of lameness or joint pathology between housing systems.     

饲料中添加高铜或高锌对猪生长发育及其肉质的影响

选用24头60日龄健康断奶长白仔猪,随机分成3组:Ⅰ组饲粮中添加含150ppm铜的含硒生长素,Ⅱ组饲粮中添加含90ppm锌的含硒生长素,Ⅲ组(对照组)饲粮中添加仅含硒生长素。结果表明:Ⅰ组日增重780g,饲料报酬1:3.83,Ⅱ组的数值相应为790g,1:3.88,Ⅲ组为779g,1:3.87,组间差异不显著(P<0.05)。肝中Cu、Zn、Fe、Mn、Se五种元素含量提高最为明显,眼肌中次之,但均未超过以往报导的正常含量。肉品质16项指标测定,15项组间差异不显著(P>0.05):17种氨基酸总量Ⅰ组为61.707％,较Ⅲ组60.055％提高2.75％;Ⅱ组60.995％,较Ⅲ组提高1.57％;统计分析组间差异不显著。这一结果提示在猪全价配合饲料中添加高剂量的Cu或Zn,当日增重达到较高水平时,对生长发育及肉质无不良影响。     

Active immunization against ghrelin decreases weight gain and alters plasma concentrations of growth hormone in growing pigs

Ghrelin has been implicated in the control of food intake and in the long-term regulation of body weight. We theorize that preventing the ability of ghrelin to interact with its receptors, would eventually lead to decreased appetite and thereby decrease body weight gain. To test our hypothesis, pigs were actively immunized against ghrelin. Ghrelin((1-10)) was conjugated to BSA and emulsified in Freund's incomplete adjuvant and diethylaminoethyl-dextran. Primary immunization was given at 19 weeks of age (WOA), with booster immunizations given 20 and 40 days after primary immunization. Body weight (BW) and plasma samples were collected weekly beginning at 19 WOA, and feed intake was measured daily. Fourteen days after primary immunization, the percentage of bound (125)I-ghrelin in plasma from immunized pigs was increased compared with control animals (P<0.001). Voluntary feed intake was decreased more than 15% in animals that were actively immunized against ghrelin compared with controls. By the end of the experiment, immunized pigs weighed 10% less than control animals (P<0.1). Concentrations of GH were increased (P<0.05) in immunized pigs. Apoptosis was not observed in post-mortem samples obtained from the fundic region of the stomach. Our observations suggest that immunization against ghrelin induces mild anorexia. This procedure could potentially be used as a treatment to control caloric intake and obesity.     

微生物植酸酶对猪钙、磷利用率及骨骼发育的影响

本试验旨在研究从断奶到肥育结束,在饲粮中添加微生物植酸酶对猪钙、磷代谢及骨骼发育的影响。试验采用完全随机设计,将72头35日龄断奶的仔猪分为4组,每组3个重复,每个重复6头。试验在相同钙水平基础上设4个组,分别为:1)玉米-豆粕基础日粮(对照组);2)基础日粮 植酸酶-50%磷酸氢钙(处理1);3)基础日粮 植酸酶-75%磷酸氢钙(处理2);4)基础日粮 植酸酶-100%磷酸氢钙(处理3)。试验期按体重分3个阶段:8~20 kg、20~50 kg、50~90 kg,3个阶段植酸酶的添加量分别为750、500和250 U/kg。试验结果表明:(1)在8~20 kg和20~50 kg阶段,添加植酸酶的3个处理,钙、磷消化率显著高于对照组(P<0.05);血钙和血磷浓度,处理1和处理2与对照组无显著差异(P>0.05),处理3显著低于对照组(P<0.05)。在50~90 kg阶段,添加250 U/kg植酸酶代替100%磷酸氢钙,血磷、血钙浓度显著低于对照组(P<0.05);(2)在试验的3个阶段添加植酸酶同时降低饲粮无机磷水平,对血清碱性磷酸酶活性均无显著影响(P>0.05);(3)添加植酸酶使胃中植酸磷消化率显著提高(P<0.0 1),粪中磷排出量显著降低(8~2 0 kg、2 0~5 0 kg阶段,P<0.0 1;5 0~9 0 kg阶段,P<0.0 5);(4)添加植酸酶代替50%或75%磷酸氢钙,猪的掌骨灰分与采食正常磷日粮的对照组无显著差异,但代替100%磷酸氢钙组,猪的掌骨灰分和蹠骨强度则显著低于对照组(P<0.05);添加植酸酶代替50%磷酸氢钙组,猪的蹠骨强度显著高于对照组(P<0.05),代替75%磷酸氢钙组与对照组差异不显著(P>0.05)。总之,在断奶和生长阶段,在猪玉米-豆粕日粮中添加植酸酶可代替部分磷酸氢钙,促进了钙、磷消化利用,促进了骨骼生长,也促进了植酸磷的利用,降低了粪磷排出。     

Genetic Differences in Energy Partitioning in Growing Pigs

Energy partitioning was studied in pigs differing in potential for carcass lean growth and fatty tissue content from 25 to 105 kg body weight, by the means of repeated measures of detailed body composition and individual feed intake. In total, 141 pigs were included from the three genetic groups Norwegian Landrace (lean and efficient), Duroc and Landrace 2 LP (a fat and slow-growing selection line) (LLP). Individual feed consumption was registered, and detailed body composition measured repeatedly by computed tomography. Energy consumption [MJ metabolizable energy (ME) day -1 ] did not differ between the genetic groups. In general, about 40-50% of consumed energy was partitioned to growth. The genetic groups partitioned equal proportions of daily energy consumption to growth (ME GROWTH ) and maintenance (MEm) early and late in the growth period. From 50 to 85 kg body weight Landrace partitioned more to growth and less to maintenance compared with Duroc ( P <0.05). When considering partitioning of ME above maintenance, the genetically fat LLP had the highest net energy retention relative to the heat increment of feeding and was therefore the most efficient, Duroc was in an intermediate position while the lean Landrace had the lowest proportion. The partitioning of ME GROWTH to fatty tissue and carcass lean growth differed between the genetic groups ( P <0.001) according to genetic potential for carcass lean and fatty tissue gain. Increasing proportions were partitioned to fatty tissue growth with increasing body weight. The genetic groups partitioned equal proportions of ME GROWTH to non- fat visceral components (NFVC) growth. MEm varied between 0.65 and 0.68 MJ kg -0.75 day -1 . MEm increased with increasing weight of carcass lean and viscera ( P <0.01), more so in the modern breeds than in the LLP.     

Estimated Mature Weights and Growth Curves for Large White Sows

Mature weight for Large White sows was estimated as the asymptote of a negative exponential growth curve. The data consisted of 2620 weight recordings from 147 sows for the period 1995?1999. Body weight was recorded every 2 weeks from 150 days of age until first service and at parturition and weaning in each parity. A starting point of 150 days was chosen in order to fit the Brody function to the data. Estimates of mature weight in relation to the number of records available (5?10, 11?15, 16?20 and >20) per sow were 285, 258, 260 and 270 kg, respectively. The goodness of fit was calculated as a residual standard deviation (9.7?15.4). No significant effect on mature weight was found for feeding level during rearing or age at first service. The estimated mature weights increased with the number of records available and was more reasonable if the weights were collected throughout the growth and reproductive period.     

高剂量铜对猪促生长作用机理的研究进展

本文概述了高钢对猪促生长的几种可能的作用机理和最新进展。作者认为铜对猪的促生长作用很可能是系统性的，而不只是以往通常认为的只限于胃肠道抗微生物作用；提示养猪生产中要研制和应用高效吸收利用的新型有机铜源，以最大地发挥铜对猪的促生长效应，同时减少银排出对环境的污染。     

四川省外种猪雌激素受体基因对繁殖和生长性状的影响

本试验以四川省外种母猪的 3个品种 (大约克、长白、杜洛克 )为研究对象 ,采用PCR RFLPs的方法检测其ESR基因的PvuⅡ多态性 ,分析了该基因与产仔数及生长性状之间的关系。结果表明 :初产胎次中 ,ESR基因型间总产仔数 (TNB)和产活仔数 (NBA)差异极显著 (P <0 .0 1) ,BB和AA纯合子间TNB和NBA分别相差 5 .97和 3.72头 ,基因加性效应分别为每个B基因 2 .98和 1.86头 ;对于经产胎次 ,总产仔数 (TNB)在AA、AB基因型与BB基因型的差异达到 0 .0 1的极显著水平 ,产活仔数 (NBA)在AA基因型与BB基因型间显著差异 (P <0 .0 5 ) ,TNB和NBA母猪每窝BB纯合子比AA纯合子分别多 3.6 8和 2 .89头 ,基因的加性效应为每个B基因分别为 1.84和 1.4 4头。头胎和经产胎次中ESR基因型在初生窝重、2 0日龄头数和窝重、30 / 4 5日龄头数和窝重以及 70日龄窝重之间的差异普遍不显著 (P >0 .0 5 ) ,但是以上 6个性状在ESR基因的 3种基因型间存在BB >AB >AA的趋势     

Evaluating the quality of feed fats and oils and their effects on pig growth performance

Feed fats and oils provide significant amounts of energy to swine diets, but there is large variation in composition, quality, feeding value, and price among sources. Common measures of lipid quality include moisture, insolubles, and unsaponifiables (MIU), titer, and free fatty acid content, but provide limited information regarding their feeding value. Lipid peroxidation is an important quality factor related to animal growth performance and health, but maximum tolerable limits in various lipids have not been established. Several indicative assays can be used to detect the presence of various peroxidation compounds, but due to the complexity and numerous compounds produced and degraded during peroxidation process, no single method can adequately determine the extent of peroxidation. Until further information is available, using a combination of peroxide value, thiobarbituric acid reactive substances (TBARS), and anisidine value appear to provide a reasonable assessment of the extent of peroxidation in a lipid at a reasonable cost. However, fatty acid composition of the lipid being evaluated should be considered when selecting specific assays. Predictive tests can also be used to estimate the stability or susceptibility of lipids to peroxidation and include active oxygen method, oil stability index, and oxygen bomb method. A review of 16 published studies with pigs has shown an average decrease of 11.4% in growth rate, 8.8% feed intake fed isocaloric diets containing peroxidized lipids compared to diets containing unperoxidized lipids of the same source. Furthermore, serum vitamin E content was generally reduced and serum TBARS content was increased when peroxidized lipids were fed in these studies, suggesting that feeding peroxidized lipids negatively affects metabolic oxidative status of pigs. However, it is unclear if antioxidants are useful additions to lipids to maintain optimal nutritional value, or if their addition to swine diets is beneficial in overcoming a metabolic oxidative challenge.     

对两种不同饲养条件下猪生长和胴体性状的遗传与表型参数的研究

本文对自由采食和限制喂料两群猪的平均日增重(DG)、平均日采食量(FI)、饲料转化率(FCR)、P_2点背膘厚(BF)和后腿瘦肉量(HL)作了遗传分析和比较。试验猪为合成品系,主要的遗传血统为大白猪和长白猪以及少量的巴克夏猪。限制采食猪各性状的平均数和标准差为:DG 729±48.45g,FI 1.85±0.043kg,FCR 2.56±0.15,BF 15.3±1.90mlmHL 6.07±0.36kg,自由采食猪相应为:821±85.87g,2.31±0.16 kg,2.85±0.31,16.8±2.43mm,6.07±0.56kg。限制采食猪各性状的遗传力:DG 0.399,FI 0.410,FC R0.403,BF 0.619,HL 0.446,而自由采食猪分别为0.307,0.480,0.129,0.315和0.350。在限制采食下,日增重与饲料转化率、日增重与后腿瘦肉量、饲料转化率与后腿瘦肉量有很强的遗传相关,分别为-0.94,0.95和-0.97;而在自由采食下这三个相关分别为-0.46,0.97和-0.46。     

The feeding of ad libitum dietary protein to organic growing-finishing pigs

The effects of three dietary protein levels on growth, meat, and carcass traits were studied in organic pigs fed a three-phase diet. Assuming lysine was the first limiting amino acid, feeds were formulated to ileal digestible (ID) lysine content, with the ID lysine:crude protein ratio set at a constant of 4%. Feeds were also formulated to an isocaloric rate (net energy: 9.4 MJ/kg during the first feeding phase, 9.25 MJ/kg during the second feeding phase and 9.1 MJ/kg during the finisher phase), with a high (HP), a medium (MP) or a low (LP) protein content ranging from 20% to 14% crude protein (CP). ID lysine content of the LP and MP feed was, respectively, 80% and 90% of the ID lysine content of the HP feed. The nutrient formulation of the HP feed was similar to nutrient levels commonly used in conventional Belgian pig farming. From 20 to 40 kg liveweight, the pigs showed better feed conversion ratios, with an increasing dietary protein concentration (r(2)=0.84). This effect was not observed in the second and third phases, although a significant effect of protein concentration on voluntary feed intake in the second phase did occur (P=0.018), probably as a compensation for the lower protein concentration in the LP diet. Analysis of the carcasses showed a lower meat percentage with lower protein concentration (P<0.05), whereas influences on meat quality were limited. It was concluded that whereas during the first phase of growth, higher protein concentration leads to better performance, from the second phase onwards (45 kg), at least with isocaloric diets, a decrease in protein content (corresponding to a 10% reduction in dietary ID lysine levels compared to conventional pig fattening) may be used in organic growing-finishing pig nutrition.     

单性状选择生长速度或背膘厚母猪身体组成的变化及其与繁殖性能的关系

本研究利用荷兰大白猪单性状选择生长速度或背膘厚2个品系的实验数据，分析了母猪身体组成性状的相关变化及其与繁殖性能的相关。选择性状175日龄体重和背膘厚与第一肥产仔数的相关为0．17和0．41，母猪身体组成性状体重和背膘与产仔存在正的较强相关，并表现年龄趋势，配种前体重、背膘是繁殖性能更好的预测者。哺乳期失重的遗传力为0．25，与下一胎产仔数的遗传相关为－0．76，与175日龄体重和背膘厚的遗传相关为－0．47和－0．41。快速生长系母猪身体组成性状的遗传趋势均为显著正值，低背膘系则相反。结果表明：选择生长速率，母狸身体组成和产仔数为正向变化，选择低背膘厚则相反；哺乳期失重存在较大的遗传变异，并与随后胎次的产仔数相关密切，应引起猪育种者的重视。     

Repeated administrations of adrenocorticotropic hormone during gestation in gilts: Effects on growth, behaviour and immune responses of their piglets

This study investigated whether repeated administrations of adrenocorticotropic hormone (ACTH) during mid or late gestation, a treatment which induces endogenous cortisol release, affect growth performance, early vitality, open-field behaviour and immune responses of neonatal pigs. Administrations of ACTH (100 IU per animal, Synacthen^® Depot) were given intramuscularly to gilts every second day either during mid (Day 49 until 75, Experiment 1) or late gestation (Day 85 until 107, Experiment 2). Control gilts received repeated injections of saline. The repeated ACTH stimulation of gilts during late gestation significantly reduced their daily weight gain during this period, but not when applied during mid gestation. Gestation length, number of born piglets and vitality measures of the newborn piglets, such as the rectal temperatures after birth and times elapsed between birth and first udder contact or milk uptake were not affected by the prenatal treatments. Administration of ACTH during late but not during mid gestation significantly increased the birth weights of piglets, and this difference in postnatal body weight was detectable until an age of 21 days. In addition, only the stimulation with ACTH during late gestation had an immunosuppressive effect on the lymphocyte proliferation of piglets 1 day after birth in response to the T-cell mitogen ConA and, in tendency, on the proliferation in response to the B-cell mitogen LPS. Twenty-four day old piglets from gilts treated during late gestation showed significantly more escape behaviour in an open-field than piglets from control litters. In conclusion, elevated maternal glucocorticoid levels during critical periods of prenatal development in pigs may affect prenatal growth, cell-mediated immunity and emotional reactivity in the neonatal piglets. The occurrence of these effects depends on the timing of increased maternal cortisol levels during gestation.