黑貉TYRP1基因的克隆及生物信息学分析

为探明黑貉酪氨酸酶相关蛋白1（tyrosinase-related protein 1,TYRP1）基因CDS序列并对其进行生物信息学分析,试验采集黑貉背部皮肤组织提取RNA后反转录为cDNA,根据GenBank中犬科TYRP1基因mRNA序列（登录号：NM_001194966.1）设计1对特异性引物,通过RT-PCR扩增TYRP1基因CDS区,将其插入到克隆载体中,对阳性菌落经PCR验证和序列测定后进行生物信息学分析。结果显示,黑貉TYRP1基因CDS序列全长为1 614 bp,编码537个氨基酸,所编码蛋白属于不稳定可溶性的亲水蛋白质。TYRP1基因与狐的遗传距离较近,说明该基因在不同物种及进化过程中具有高度保守性。TYRP1蛋白二级结构中,无规则卷曲所占比例最高,为54.0%;α-螺旋次之,为29.8%。TYRP1蛋白三级结构主要由大量无规则卷曲和α-螺旋构成,与二级结构相一致。TYRP1蛋白具有氧化还原酶活性,参与DNA修复和复制、蛋白质合成和降解,可与TYR、DCT、TP53、TRPC1等多种蛋白相互作用。本试验结果为进一步探索TYRP1基因在哺乳动物毛色遗传机制中的功能提供了理论依据。     

银黑狐TYRP1基因CDS区鉴定及生物信息学分析

为了探明酪氨酸酶相关蛋白1(TYRP1)基因对狐狸毛色的调控机制,本研究利用RT-PCR、染色体步移和核酸测序等技术,获得了银黑狐TYRP1基因完整编码区(coding DNA sequence,CDS),利用ProtParam和PredictProtein等在线软件对该基因进行了生物信息学分析,并利用Lasergene7.1软件包进行银黑狐与其他物种间的同源性分析及系统进化树的构建。结果表明,银黑狐TYRP1基因CDS区共计1 614bp,编码537个氨基酸残基,属于不稳定可溶性亲水蛋白质。亚细胞定位主要在内质网和高尔基体中,属于分泌蛋白。在第24和25个氨基酸之间存在1个裂解位点,存在信号肽。其属跨膜蛋白,包括跨膜域、胞外域和胞内域3个部分。二级结构以无规则卷曲为主(59.03%),α-螺旋占22.91%,属卷曲蛋白质。三级结构与二级结构预测结果基本一致,主要是由无规则卷曲和α-螺旋构成。银黑狐与其他10个物种间的相似度为88.6%~99.6%,说明物种之间同源性较高,TYRP1基因编码区在进化过程中保守性较强。系统进化分析提示,银黑狐与赤狐和家犬的遗传亲缘关系最近。银黑狐TYRP1基因编码区的成功获取及分析为进一步探讨其在毛色形成过程中的功能研究提供了较好的理论依据。     

水貂毛色关联TYRP2基因编码区序列鉴定及比较基因组学分析

探究水貂酪氨酸酶相关蛋白2(TYRP2)基因的分子结构特性及其调控被毛色素沉积的生理功能。利用比较基因组学方法基于水貂皮肤转录组测序获得的TYRP2基因完整编码区(CDS)核苷酸及其编码氨基酸序列的结构特性开展了系统的生物信息学预测及比较基因组学分析。结果:RNA-seq获取的水貂TYRP2基因长度为3 385 bp,CDS长度1 554 bp,共编码517个氨基酸。进一步分析发现,TYRP2编码蛋白二级结构以α-螺旋和无规则卷曲为主,属混合型二级结构,为酸性不稳定亲水蛋白质;含有1个信号肽,1个跨膜区,形成8对二硫键,包括46个磷酸化位点与7个糖基化位点,179～409位氨基酸为酪氨酸酶家族共有核心结构域。亚细胞定位显示,水貂TYRP2蛋白位于细胞外,属一种分泌型蛋白,主要在细胞内质网中发挥其生物学功能。编码氨基酸序列比对表明,水貂与其他10个食肉目物种TYRP2基因编码氨基酸序列均存在2个保守的铜离子结合位点:CuA和CuB。水貂TYRP2基因鉴定及序列分析为解析其调控被毛色素沉积的生理功能提供了详尽的生物学基础信息。     

驴Zfx基因CDS序列克隆及序列分析

本研究旨在克隆驴Zfx基因CDS序列,并对其进行生物信息学分析。根据GenBank中公布的牛Zfx基因mRNA序列(登录号:D84097.1)设计特异性引物,利用RT-PCR技术获取驴Zfx基因CDS序列,并对驴Zfx基因CDS区核苷酸序列和蛋白质结构进行生物信息学分析。结果表明,驴Zfx基因CDS区序列长度为2 403 bp,编码800个氨基酸;驴与马、牛、家犬、白犀牛、马鹿、猫、人、绵羊、黑猩猩的Zfx基因CDS区核苷酸序列同源性分别为99.6%、95.0%、95.3%、97.9%、93.5%、94.9%、95.0%、95.7%和94.9%。对驴及其他9种哺乳动物Zfx基因CDS区的核苷酸序列构建系统进化树,结果显示,驴与马亲缘关系很近,与白犀牛的亲缘关系次之;同时又与聚在一类的家犬、猫亲缘关系较近,而与绵羊、牛的亲缘关系稍远。Zfx蛋白理论等电点(pI)为5.19,不稳定系数为42.94,消光系数为35 810,属于不稳定的亲水性蛋白,含有60个磷酸化位点,无信号肽及跨膜结构,属于非分泌蛋白。Zfx蛋白α-螺旋、延伸链和无规则卷曲分别为23.12%、20.25%和56.63%,三级结构主要为α-螺旋和无规则卷曲。本试验成功克隆获得驴Zfx基因CDS序列,为后期深入研究该基因及其编码蛋白的结构功能提供依据。     

草鱼HSP70基因生物信息学分析

本研究采用生物信息学方法,对草鱼HSP70基因编码蛋白质的理化特性和结构进行了分析和预测。结果表明,草鱼HSP70基因编码573个氨基酸,组成的蛋白质为不稳定的水溶性蛋白。二级结构为混合型,三级结构是由α-螺旋、β-折叠、β-转角和无规则卷曲构成。     

小尾寒羊GnRH基因CDS区的生物信息学分析

为探讨小尾寒羊GnRH基因CDS区编码蛋白的性质和功能,采用生物信息学相关软件和工具对小尾寒羊GnRH基因编码蛋白的理化性质、结构功能及其同源进化关系进行了分析预测。结果显示:小尾寒羊GnRH基因CDS区编码328个氨基酸,产物为一种不溶于水的稳定性蛋白,蛋白质的二三级结构主要由α-螺旋和无规则卷曲构成;蛋白质功能预测结果显示,该蛋白在信号转导、免疫应答过程以及生长因子和荷尔蒙分泌中发挥作用的几率相对较高;同源性分析发现,小尾寒羊GnRH基因编码氨基酸序列与山羊的同源性较高。说明GnRH基因在羊的生殖调控和免疫应答中发挥着重要作用。     

牛SCD1基因的生物信息学分析

本研究利用生物信息学方法分析和预测牛SCD1基因的理化特性和编码产物的结构。结果表明牛SCD1基因编码359个氨基酸,平均分子质量为41.71 k Da;组成蛋白为不稳定的水溶性蛋白,三级结构由α-螺旋和无规则卷曲组成,并且牛SCD1基因氨基酸序列和山羊亲缘关系最近。牛SCD1基因的生物信息学分析为进一步研究牛SCD1基因的遗传特性和生理机制奠定了基础。     

犬IFN-β的克隆及其序列分析

为了分析犬干扰素β(IFN-β)基因分子特征,预测其编码蛋白质的生物学功能,根据GenBank登录的犬IFN-β基因序列(FJ194477)设计合成特异性引物,通过PCR从外周血淋巴细胞总DNA中扩增IFN-β基因CDS区并克隆,应用生物信息学方法对犬IFN-β基因进行序列分析,并对其理化性质以及编码蛋白的二级结构、三级结构进行预测,构建分子系统进化树。结果表明:犬IFN-β基因编码区全长561 bp,共编码186个氨基酸,其分子式可表示为C_(1014)H_(1593)N_(263)O_(290)S_9,分子质量为22.40 ku;属于亲水性蛋白,理论等电点为5.98;含有丰富的二级结构,以α-螺旋(76.88%)和无规则卷曲(19.35%)为主,蛋白三级结构呈弯曲螺旋结构;与貉、威德尔海豹、金钱豹、家猫、宽吻海豚、人、鸡和绿头鸭相对应序列核苷酸序列同源性分别为98.4%、87.2%、85.2%、84.7%、79.0%、74.9%、43.9%和43.3%。说明犬与貉IFN-β核苷酸同源性最高,亲缘关系最近。     

绵羊TPT1基因CDS区遗传结构及组织表达研究

本研究旨在克隆绵羊TPT1基因序列,通过生物信息学分析探究其序列特征及编码蛋白的结构与功能,通过实时荧光定量PCR检测TPT1基因在绵羊不同组织中的空间表达规律。以小尾寒羊为研究对象,PCR扩增获得TPT1的完整编码区(CDS)区并进行测序,对所得序列进行生物信息学分析。结果显示:绵羊TPT1基因CDS为660 bp,编码219个氨基酸,核酸序列与山羊的同源性最高。TPT1蛋白为亲水性蛋白,主要分布在线粒体,存在16个磷酸化位点;二级结构主要包含α-螺旋和无规则卷曲,与预测的三级结构相似。定量PCR结果显示TPT1基因在肾中表达量最高,其次是肌肉、肝、脂肪和肺,在心和脾中表达量最低。结果表明,TPT1基因在生物进化中是保守的,但其表达的蛋白质结构不稳定,在绵羊不同组织中均有表达。     

保山猪和杜洛克猪IGF-1基因的SNP筛选及生物信息学分析

试验旨在探究IGF-1基因单核苷酸突变位点对保山猪和杜洛克猪生长性能的影响。试验以保山猪和杜洛克猪为研究对象,采用直接测序法对IGF-1基因的多态性进行检测,利用生物信息学软件分析编码蛋白结构。结果显示：在保山猪IGF-1基因编码蛋白的外显子上共筛选出1个SNP位点（Exon4-G189A）,该突变属于同义突变,引起密码子改变,但所编码的氨基酸未改变。生物信息学分析结果显示,保山猪IGF-1基因CDS区编码164个氨基酸,分子式为C782H1265N247O239S11,相对分子质量为18303.82,理论等电点为9.89,不稳定性指数为73.25,整体表现为亲水性,不具有跨膜结构,含有信号肽序列;蛋白质二级结构只含有无规则卷曲和α-螺旋,分别占60.37%、39.63%,三级结构预测模型与保山猪IGF-1基因的蛋白结构匹配度为-1.15,具有较好的一致性。研究表明,IGF-1基因在物种进化过程中高度保守,使其编码保山猪和杜洛克猪的氨基酸序列相同,蛋白质结构和功能差异很小或不存在差异,能否作为调控保山猪瘦肉少、脂肪多、生长慢的候选基因还需进行关联性的研究。     

Low‐density lipoproteins and milk serum proteins improve the quality of stallion sperm after vitrification in straws

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.     

A meta-analysis on effects of supplementing low-quality roughages with foliages from browses and tree fodders on intake and growth in sheep

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.     

Comparison of the sedative effects of intranasal or intramuscular dexmedetomidine at low doses in healthy dogs: a randomized clinical trial

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 (IN_Dex), through a mucosal atomization device in one nostril, or the intramuscular route (IM_Dex), 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 IN_Dex and IM_Dex 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 IN_Dex and IM_Dex, respectively (p = 0.799). Respiratory rate was higher in group IN_Dex (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.     

Comparison on the physico‐chemical and nutritional qualities of normal and abnormal colored fresh chicken liver

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.     

Effect of food on the pharmacokinetics of oral cefuroxime axetil in dogs

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 (C_max), 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, C_max, 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 (T_½(a)) and time to peak concentration (T_max) (0.55 ± 0.27–1.15 ± 0.19 hr and 1.21 ± 0.22–1.70 ± 0.30 for T_½(a) and T_max 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.     

Methane emissions and δ13C composition from beef steers consuming increasing proportions of sericea lespedeza hay on bermudagrass hay diets

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 (δ¹³C_CH4) 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.     

Net requirements of calcium, magnesium, sodium, phosphorus, and potassium for growth of Nellore × Red Angus bulls, steers, and heifers

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.     

Tilmicosin enteric granules and premix to pigs: Antimicrobial susceptibility testing and comparative pharmacokinetics

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 (T_max), elimination half‐life (t_1/2β), mean residence time (MRT), and apparent volume of distribution (V_F) 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 AUC_0‐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.     

High‐level exogenous trans10, cis12 conjugated linoleic acid plays an anti‐lipogenesis role in bovine mammary epithelial cells

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.     

Factors affecting dystocia and offspring vigour in different sheep genotypes

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.