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布鲁菌16M感染后宿主免疫相关蛋白质泛素化修饰的差异分析 总被引：1，自引：0，他引：1
《畜牧兽医学报》2019,(11)
为探究布鲁菌感染宿主细胞早期泛素化修饰蛋白质组表达变化并筛选出影响免疫应答的关键调控蛋白,通过Label-free和泛素化富集技术以及高分辨率LC-MS/MS联用的定量蛋白质组学研究策略,对布鲁菌16M感染11 h (感染5 h,胞内复制6 h)后的巨噬细胞和未感染布鲁菌16M的巨噬细胞进行了泛素化蛋白质组学定量研究,数据库检索分析了16M感染后的巨噬细胞和未感染的巨噬细胞差异表达的泛素化位点对应的蛋白质,并应用生物信息学方法筛选出16M感染巨噬细胞后可造成宿主免疫抑制的关键蛋白质。结果显示,共鉴定出349个蛋白质上580个泛素化位点。布鲁菌16M感染组相对于未感染组167个蛋白质上259个位点泛素化修饰水平发生上调,212个蛋白质上321个位点泛素化修饰水平发生下调(差异倍数1.5,P0.05);35个泛素化修饰差异表达的蛋白质可能与布鲁菌感染后宿主的免疫应答有关,其中27个泛素化修饰的下调蛋白质(如Bcap31、Btk、Faf1和Akap31等),1个泛素化修饰上调蛋白质Ubqln1可能是布鲁菌感染宿主后造成免疫抑制的关键蛋白。本研究筛选获得了布鲁菌16M感染宿主细胞免疫相关差异表达的泛素化修饰蛋白质,初步揭示布鲁菌能够调控宿主免疫信号通路、自噬和凋亡等免疫应答过程中相关蛋白质的泛素化修饰,为进一步研究布鲁菌感染后调节宿主泛素化修饰进而形成免疫逃逸的分子机制提供理论基础。 相似文献
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布鲁菌是一种缺乏典型毒力因子的胞内寄生菌,可以抵御宿主细胞内酸性、缺氧、强氧化性以及营养匮乏等多种不利环境,是形成布鲁菌致病力的重要原因。布鲁菌的二元调控系统可以对这些环境信号进行感应、传递并做出相应的适应。论文对布鲁菌二元调控系统的研究现状及二元调控系统在布鲁菌病防控中的应用进行了系统的介绍。 相似文献
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布鲁菌病是一种危害严重的人兽共患病,威胁着畜牧业的发展和人类的公共卫生安全。作为布鲁菌病的病原,布鲁菌能够耐受宿主体内的各种杀菌机制并持续的生存。细菌的sRNA在基因组中被转录,但绝大多数sRNA并不编码蛋白质。sRNA通过碱基配对与mRNA结合,影响mRNA的稳定性或翻译,从而调控细菌代谢、群体感应、环境应激及细菌毒力基因表达等生物过程。通过sRNA调控毒力相关基因表达,使布鲁菌可以耐受多种胞内应激环境。目前为止,仅有少数布鲁菌sRNA的功能得到了较全面的研究,论文对这些sRNA的研究进展进行综述。 相似文献
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布鲁菌病(布病)是一种严重的人兽共患病。作为布病的病原,布鲁菌能够耐受宿主体内的各种杀菌机制并持续的生存。当布鲁菌侵入宿主体内后,必须适应抗体免疫的环境,而这依赖于布鲁菌对自身基因表达的巧妙调控。Hfq蛋白是一个RNA伴侣分子,对于介导sRNA的转录后调控发挥着重要的作用。在多种细菌中,对Hfq蛋白的功能都进行了深入的研究,目前已经发现该蛋白与细菌基因的表达调控、细菌对多种应激环境的适应能力以及致病菌的毒力均有着密切的关系。论文对Hfq蛋白的结构,对sRNA的调控功能,特别是布鲁菌Hfq蛋白调控功能的研究现状及在布病疫苗研发中的应用进行系统的介绍,为布鲁菌基因的表达调控和布病防控技术的研究提供参考。 相似文献
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《中国动物传染病学报》2016,(3)
布鲁菌病是由布鲁菌感染引起的呈全球性分布的人畜共患细菌性传染病。布鲁菌是一种兼性胞内菌,感染宿主依赖多种基因的表达和调控。近年来,胞内菌的碳代谢与致病力的关系成为研究的热点。前期研究发现碳代谢相关的丙酮酸磷酸双激酶(ppdk)基因与布鲁菌毒力相关。本研究利用同源重组方法构建流产布鲁菌ppdk基因缺失株,通过环境压力因子耐受性实验、胞内存活实验和动物致病性实验等探讨ppdk基因对布鲁菌毒力的影响。结果显示,ppdk基因缺失能减弱布鲁菌对多粘菌素B和大牛血清的抵抗性,减弱细菌胞内存活的能力和对小鼠的致病力,表明ppdk基因与流产布鲁菌的毒力密切相关。 相似文献
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布鲁菌是一种重要的人畜共患病病原,兼性胞内寄生,无典型毒力因子,毒力相关基因的研究对阐明布鲁菌持续感染的机制具有重要意义。本研究以流产布鲁菌S2308为亲本株,通过同源重组的方法,构建流产布鲁菌LysR家族转录调控子基因bab＿RS24670缺失株ΔlttR8,基于广宿主质粒pBBR1MCS构建成互补株ΔlttR8-Com。免疫印迹试验表明：ΔlttR8为光滑型菌株;体外培养分析发现lttR8缺失不影响布鲁菌的生长;细胞感染试验发现lttR8缺失不影响布鲁菌黏附、入侵细胞和胞内存活的能力。耐受性试验分析发现：lttR8缺失不影响布鲁菌对过氧化氢（H2O2）和多粘菌素B(polymyxin B)的敏感性。小鼠感染试验分析发现lttR8缺失显著减弱流产布鲁菌的毒力。综上所述,本研究发现一个新的与流产布鲁菌致病性相关的转录调控子,为布鲁菌致病机制研究提供参考。 相似文献
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Cesar Consuegra Francisco Crespo Jesús Dorado Maria Diaz‐Jimenez Blasa Pereira Manuel Hidalgo 《Reproduction in domestic animals》2019,54(Z4):86-89
Lipids and proteins can be used for sperm vitrification to preserve the integrity of sperm membranes or to increase the viscosity of the medium. This study evaluated the effect of low‐density lipoproteins (LDL) and milk serum proteins (Pronexcell) for stallion sperm vitrification. Hippex extender (Barex Biochemical Products, The Netherlands), plus 1% of bovine serum albumin and 100 mM of trehalose, was used as control for sperm vitrification. In experiment 1, different concentrations of LDL (L1 = 0.25, L2 = 0.5, L3 = 1%) and in experiment 2 of Pronexcell (P1 = 1, P2 = 5, P3 = 10%) were added to control extender. Vitrification was performed in 0.25‐ml straws directly plunged into liquid nitrogen. Total motility (TM, %) and progressive motility (PM, %) were analysed by CASA, and plasma membrane (IMS, %) and acrosome membrane integrity (AIS, %) were assessed under epifluorescence microscopy. Post‐warmed sperm parameters were compared between treatments by ANOVA. Results were expressed as mean ± SEM. In both experiments, the minimum concentration of LDL and Pronexcell obtained significantly higher values (p < 0.01) than the control extender for TM (L1 = 52.95 ± 4.4; P1 = 58.99 ± 4.6; C = 30.88 ± 3.0), PM (L1 = 36.79 ± 5.5; P1 = 47.25 ± 4.3; C = 19.20 ± 2.4), IMS (L1 = 68.88 ± 3.6; P1 = 47.25 ± 4.3; C = 52.81 ± 2.6) and AIS (L1 = 45.88 ± 3.6; P1 = 47.25 ± 4.3; C = 26.00 ± 2.1). No differences in sperm parameters were found among different concentrations of LDL or Pronexcell. In conclusion, the addition of 0.25% LDL and 1% Pronexcell to the vitrification extender is recommended to improve the quality of stallion sperm after vitrification. 相似文献
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A meta-analysis of data obtained from previous studies was conducted to understand the responses of foliage supplementation on intakes of basal DM (BDMI) and total DM (TDMI), and daily gain (ADG). Thirty-four published studies containing 223 treatments and 1127 sheep met criteria for inclusion in the meta-analysis. Major predictive variables considered were percentages of foliages in diet (SD), CP in foliages (PS), NDF in foliages (FS), NDF in forages (FB), CP in basal roughages (PB), CP in diet (PD) and foliage CP intake (SPI). TDMI (g/d) increased quadratically (P < 0.001) with increasing PS, FS, SPI (R2 = 0.66), PB, SD (R2 = 0.58) and PD (R2 = 0.73). The maximal response of TDMI were 778 g/d at 42% of SD, 894 g/d at 19.8% PD, 893 g/d at 148 g/d SPI and 749 g/d at 26.4% PS (P < 0.001; R2 = 0.58, 0.73, 0.66, and 0.37, respectively). BDMI increased quadratically with increasing SD, PD and PB, but decreased quadratically (P < 0.001) with increasing PS (P < 0.001; R2 = 0.07). The breakpoint of BDMI was 570 g/d at 6.58% of PD in the diet (P < 0.001, R2 = 0.28). Overall, BDMI responded at very low level of SD in the diet, peaking at 7.6% SD with BDMI of 572 g/d (P < 0.001, R2 = 0.72). However, when PB was less than 3%, the maximal BDMI was 489 g/d at foliage levels of 25.7%. When PB was between 3 and 6%, maximal BDMI was at 13% of foliage in the diet and the basal forage intake of 597 g/d; whereas, BDMI decreased linearly with SD when PB was greater than 6%. BDMI (g/d) decreased quadratically when foliage CP percentages were lesser than 10%, but increased quadratically with PS when foliage CP percentages were greater than 10%. ADG responded positively and quadratically to PS, SPI, SD, PD and TDMI (g/d) and the relationships were moderate to high. However, ADG (g/d) decreased linearly with increasing FS (P < 0.001, R2 = 0.35). The maximal ADG was 42 g/d at 43% of SD, 41 g/d at 9.4% PD, 42 g/d at 53 g/d SPI, 35 g/d at 25% PS and 46 g/d at TDMI of 889 g/d (P < 0.001; R2 = 0.74, 0.84, 0.74, 0.29 and 0.74, respectively). It is concluded that the interactions of quality and quantity of foliage supplements and quality of basal forages affect intakes of basal and total DM, and growth in sheep. 相似文献
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《Veterinary anaesthesia and analgesia》2022,49(6):572-579
ObjectiveTo compare the sedative effects of dexmedetomidine administered either intranasally or intramuscularly to healthy dogs.Study designProspective, randomized, blinded, clinical trial.AnimalsA group of 16 client-owned healthy dogs.MethodsDogs were randomly allocated to one of two groups that were administered dexmedetomidine 5 μg kg–1 via either the intranasal route (INDex), through a mucosal atomization device in one nostril, or the intramuscular route (IMDex), into the epaxial muscles. Ease of intranasal administration, sedation score, onset of sedation, cardiopulmonary variables, mechanical nociceptive thresholds (MNTs) and response to venous catheterization were recorded at 0 (baseline), 5, 10, 15, 20, 25, 30, 35, 40 and 45 minutes, following drug administration. Data were compared with the one-way anova, Mann-Whitney U test, and chi-square test, where appropriate.ResultsGroups were not different for age, sex, weight, body condition score or temperament. Sedation scores, MNTs and response to intravenous catheter placement were not different when dexmedetomidine was administered by either route (p = 0.691; p = 0.630 and p = 0.435, respectively). Onset of sedation was not different between groups INDex and IMDex reaching a score of 4.2 ± 0.9 and 5.5 ± 1.2 at 9 ± 5 and 8 ± 4 minutes, respectively (p = 0.467). The highest sedation score was achieved at 30 and 35 minutes and sedation scores were 9.7 ± 2.0 and 9.5 ± 2.3 in groups INDex and IMDex, respectively (p = 0.799). Respiratory rate was higher in group INDex (p = 0.014), while there were no differences between routes in heart rate (p = 0.275), systolic (p = 0.957), diastolic (p = 0.837) or mean arterial pressure (p = 0.921).Conclusions and clinical relevanceIntranasal administration of dexmedetomidine at 5 μg kg–1 provides effective sedation in healthy dogs. 相似文献
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Comparison on the physico‐chemical and nutritional qualities of normal and abnormal colored fresh chicken liver 
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下载免费PDF全文 Guoyuan Xiong Xueqin Gao Haibo Zheng Xin Li Xinglian Xu Guanghong Zhou 《Animal Science Journal》2017,88(6):893-899
This study evaluated the differences of physico‐chemical and nutritional qualities between abnormal colored chicken livers (ANCCLs) and normal colored chicken livers (NCCLs) and the safety of the both livers. Compared with NCCLs, ANCCLs were lower in protein, water contents (P < 0.01), pH and pigment contents (P < 0.05). NCCLs contained higher polyunsaturated fatty acid (PUFA) and saturated fatty acids (SFA) (P < 0.05). The PUFA/SFA ratio of NCCLs was 0.453, higher (P < 0.05) than that of ANCCLs. The contents of alanine, valine, tyrosine, lysine and histidine in NCCLs were higher (P < 0.05) than in ANCCLs. The contents of K, Na, P, Cu, Fe and Se of NCCLs were higher (P < 0.05), but the Ca content was lower (P < 0.05). The content of the heavy metals (As, Hg, Pb and Cd) of the two types of livers complied with food safety requirements. Although NCCLs had higher nutritional value than ANCCLs, both livers were acceptable for human consumption. 相似文献
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Gabriela A. Albarellos Sabrina M. Passini Martín P. Lupi Silvia Aramayona Paula M. Lorenzini Laura Montoya Maria F. Landoni 《Journal of veterinary pharmacology and therapeutics》2020,43(3):297-302
Cefuroxime axetil pharmacokinetic profile was investigated in 12 Beagle dogs after single intravenous and oral administration of tablets or suspension at a dose of 20 mg/kg, under both fasting and fed conditions. A three-period, three-treatment crossover study (IV, PO under fasting and fed condition) was applied. Blood samples were withdrawn at predetermined times over a 12-hr period. Cefuroxime plasma concentrations were determined by HPLC. Data were analyzed by compartmental analysis. No statistically significant differences were observed between formulations and feeding conditions on PK parameters. Independently of the feeding condition, absorption of cefuroxime axetil after tablet administration was low and erratic. The drug has been quantified in plasma in 3 out of 6 and 5 out of 6 dogs in the fasted and fed groups. For this formulation, the bioavailability (F), peak plasma concentration (Cmax), and area under the concentration–time curve (AUC) of cefuroxime axetil were significantly enhanced (p < .05) by the concomitant ingestion of food (32.97 ± 13.47–14.08 ± 7.79%, 6.30 ± 2.62–2.74 ± 0.66 µg/ml, and 15.75 ± 3.98–7.82 ± 2.76 µg.hr/ml for F, Cmax, and AUC in fed and fasted dogs, respectively), while for cefuroxime axetil suspension, feeding conditions affected only the rate of absorption, as reflected by the significantly shorter absorption half-life (T½(a)) and time to peak concentration (Tmax) (0.55 ± 0.27–1.15 ± 0.19 hr and 1.21 ± 0.22–1.70 ± 0.30 for T½(a) and Tmax in fed and fasted dogs, respectively). For cefuroxime axetil tablets, T > MIC (≤1 µg/ml) was <2 hr in fasted and ≈4 hr in fed animals, and for cefuroxime axetil suspension, T > MIC (≤1 µg/ml) was ≈5 hr and for T >MIC (≤4 µg/ml) was ≈2.5 hr for fasted and fed dogs, respectively. Cefuroxime axetil as a suspension formulation seems to be a better option than tablets. However, its short permanence in plasma could reduce its clinical usefulness in dogs. 相似文献
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Flavia O S van Cleef Jos C B Dubeux Jr. Harley D Naumann Erick R S Santos Lynn E Sollenberger Joo M B Vendramini Martin Ruiz-Moreno Francine M Ciriaco Nicolas DiLorenzo 《Journal of animal science》2021,99(8)
An experiment was conducted to evaluate the effects of different proportions of ‘Au Grazer’ sericea lespedeza [SL, Lespedeza cuneata (Dum. Cours.) G. Don], a legume rich in condensed tannins (CT), on nutrient intake and digestibility, and to estimate methane (CH4) emissions and 13C isotopic composition (δ13CCH4) from beef steers consuming a forage-based diet. Twenty-five Angus-crossbred steers were distributed in a randomized complete block design (344 ± 48 kg initial BW), and randomly assigned to one of five treatments: 0SL, 25SL, 50SL, 75SL, and 100SL, diets containing 0%, 25%, 50%, 75%, and 100% of SL hay, respectively, mixed with ‘Tifton-85’ bermudagrass hay (Cynodon spp.). The study was carried out for two experimental periods of 21-d each. The statistical model included the fixed effect of treatment and random effects of block, experimental period, and their interaction. Apparent total tract digestibility of crude protein, neutral detergent fiber, and acid detergent fiber was linearly decreased (P < 0.001) by the inclusion of SL. No effects were observed for total CH4 emissions per day, nor for CH4 relative to organic matter intake or digestible organic matter with the inclusion of SL. However, emission of CH4 in relation to intake of CT was affected by treatment (P < 0.001). A linear (P < 0.001) decrease and a quadratic effect (P < 0.001) were observed for δ13C of diets and gas, respectively, in which diets and enteric CH4 with greater inclusion of SL were more depleted in 13C. Moreover, the difference in δ13C between diets and gas (Δδ13C) had a linear decrease (P = 0.001) with the inclusion of SL. The model developed to predict the C3 proportions in the enteric CH4 fitted to predicted values (P < 0.0001). Therefore, greater proportions of SL resulted in lesser CH4 emission when CT intake was considered and the isotopic composition from enteric CH4 was able to predict the contribution of SL in the emissions. 相似文献
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Net requirements of calcium, magnesium, sodium, phosphorus, and potassium for growth of Nellore × Red Angus bulls, steers, and heifers 总被引：1，自引：0，他引：1
Mario Luiz Chizzotti Sebastio de Campos Valadares Filho Luis Orlindo Tedeschi Pedro Veiga Rodrigues Paulino Mrio Fonseca Paulino Rilene Ferreira Diniz Valadares Paloma Amaral Pedro Del Bianco Benedeti Tainnah Ikegami Rodrigues Mozart Alves Fonseca 《Livestock Science》2009,124(1-3):242-247
A comparative slaughter trial was conducted to assess the net requirements for gain of Ca, P, Na, K and Mg of bulls, steers and heifers of Nellore and Red Angus crossbreds. Twenty seven F1 Nellore and Red Angus crossbred calves (9 steers, 9 bulls, and 9 heifers), averaging 274 kg BW, were used. At the beginning of the trial, three animals from each gender were slaughtered to determine the initial body composition. The remaining 18 animals (3 animals of each gender) were randomly assigned to two treatments: fed 0.75 or 1.5% of BW of concentrate. The diets were based on corn silage and were isonitrogenous (2% N, DM). After three growing periods of 28 d, all animals were slaughtered. The cleaned gastrointestinal tract, organs, carcass, head, hide, tail, feet, and tissues were weighed to determine the empty BW (EBW). These parts were ground separately and subsampled for chemical analyses. The log of the contents of each mineral in the empty body was regressed on the log of the EBW to estimate the net requirement for each mineral per kg of empty body gain (EBG). There were no differences (P > 0.05) in the net requirements for growth of all macrominerals among genders. The equations of the pooled data of the net requirements for growth (g/kg EBG) were: 332.6 × EBW − 0.6367 for Ca, 112.1 × EBW − 0.5615 for P, 10.85 × EBW − 0.3992 for Na, 4.01 × EBW − 0.153 for K, and 3.589 × EBW − 0.462 for Mg. Our findings indicated that retained Ca and retained P were poorly related to the retained protein. 相似文献
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Jincheng Xiong Qianqian Zhu Yaxin Zhao Shuaike Yang Jiyue Cao Yinsheng Qiu 《Journal of veterinary pharmacology and therapeutics》2019,42(3):336-345
The purpose of this study was to compare the pharmacokinetics and relative bioavailability of tilmicosin enteric granules and premix after oral administration at a dose of 40 mg/kg in pigs. Three kinds of different respiratory pathogens were selected for determination of minimal inhibitory concentration (MIC) to tilmicosin. Eight healthy pigs were assigned to a two‐period, randomized crossover design. A modified rapid, sensitive HPLC method was used for determining the concentrations of tilmicosin in plasma. Pharmacokinetic parameters were calculated by using WinNonlin 5.2 software. The MIC90 of tilmicosin against Haemophilus parasuis, Actinbacillus pleuropneumoniae, and Pasteurella multocida were all 8 μg/ml. These results indicated that these common pig respiratory bacteria are sensitive to tilmicosin. The main parameters of time to reach maximum plasma concentration (Tmax), elimination half‐life (t1/2β), mean residence time (MRT), and apparent volume of distribution (VF) were 2.03 ± 0.37 hr, 29.31 ± 5.56 hr, 25.22 ± 2.57 hr, 4.06 ± 1.04 L/kg, and 3.05 ± 0.08 hr, 17.06 ± 1.77 hr, 15.55 ± 1.37 hr, 2.95 ± 0.62 L/kg after the orally administrated tilmicosin enteric granules and premix. The relative bioavailability of tilmicosin enteric granules to premix was 114.97 ± 7.19%, according to the AUC0‐t values. These results demonstrated that tilmicosin enteric granules produced faster tilmicosin absorption, slower elimination, larger tissue distribution, and higher bioavailability compared to the tilmicosin premix. The present study results manifest that tilmicosin enteric granules can be used as a therapeutic alternative to premix in clinical treatment. 相似文献
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Hongfang Wang Hongyun Liu Jianxin Liu Ke Zhao Chong Wang Weiren Yang 《Animal Science Journal》2014,85(7):744-750
Primary bovine mammary epithelial cells (BMECs) were treated by 0, 37.5, 75, 112.5, 150 μmol/L trans10, cis12 conjugated linoleic acid (CLA) to evaluate the effects of different level trans10, cis12 CLA on lipogenesis in BMEC. Addition of 75–150 μmol/L trans10, cis12 CLA reduced significantly the triacylglycerol (TAG) content (P < 0.05), but did not have inhibiting action on cell proliferation (P > 0.05). Treatment with 150 μmol/L trans10, cis12 CLA for 48 h resulted in a 17.1% reduction (P < 0.0001) of medium chain fatty acids (MCFA, C14 < C < C16), a 26.5% reduction (P < 0.0001) of unsaturated fatty acids (UFA) and a corresponding reduction of the mRNA abundance of acetyl coenzyme A (acetylCoA) carboxylase (ACC) (P = 0.046), fatty acid synthase (FAS) (P = 0.017) and stearoylCoA desaturase1 (SCD1) (P = 0.002). Another finding was that trans10, cis12 CLA elevated expression of diacylglycerol acyltransferase2 (DGAT2) (P = 0.020) and long chain acylCoA synthetases (ACSL) (P = 0.032). In conclusion, higher trans10, cis12 CLA, not low trans10, cis12 CLA, inhibited milk fat synthesis and changed fatty acid composition by regulating the expression of FAS, ACC, SCD1, DGAT2 and ACSL. 相似文献
20.
Birth difficulty and poor lamb vigour are significant causes of perinatal lamb mortality. In this study we investigated whether sheep breeds differing in appearance, muscularity and selection history also had differences in dystocia and lamb vigour, and considered some of the factors that may contribute to the variation in these traits. Data were collected at birth from a total of 3252 lambs of two terminal sire breeds selected for lean growth (Suffolk [S], n = 500 and Texel [T], n = 1207), from a Hill breed (Scottish Blackface [B], n = 610), which has been mainly selected for hardiness, and a crossbred (Mule × T [M], n = 935) representing a maternal line. For each lamb the degree of assistance at delivery, lamb presentation, amount of assistance to achieve successful sucking, sex, litter size and birth weight were recorded. T lambs required the most, and B and M lambs the least assistance at birth, S lambs were intermediate (% lambs assisted: T = 55.7, S = 30.7, B = 22.7, M = 24.9, P < 0.001). T and S lambs were equally likely to be malpresented at birth (29% of births) and more likely to be malpresented than B or M lambs (20%; P < 0.001). In T and S breeds lambs requiring veterinary assistance at delivery were mainly heavy and singleton lambs, whereas in B and M breeds these were exclusively low birth weight lambs in multiple litters. Although heavier lambs needed greater birth assistance, T lambs were lighter than S and M lambs, but heavier than B lambs (birth weight (kg): S = 4.66, M = 4.56, T = 4.32, B = 3.67, P < 0.001). S lambs were more likely to require assistance with sucking than other breeds, and T lambs also required more assistance than B or M lambs (% lambs assisted to suck: S = 56.0, T = 31.6, M = 19.8, B = 18.4, P < 0.001). Heavier lambs were more likely to suck unaided than lighter lambs (P < 0.001). The data suggest that the two terminal sire breeds, selected narrowly for greater productivity (muscle growth and conformation), are more likely to experience birth difficulty and poorer lamb vigour than the breed selected for hardiness, or the cross breed. Whether these effects arise as a consequence of genetic selection (e.g. for specific lamb conformation), or as a result of management practices to achieve selection goals (e.g. increased intervention at lambing) is unknown. Specific actions to improve birth difficulty and lamb vigour, such as including these traits in the selection index, would be beneficial in improving the welfare of ewes and lambs of the terminal sire breeds. 相似文献