地克珠利对肉鸡生长、屠宰性能、免疫机能及血清生化指标的影响

选用288只1日龄AA肉鸡,随机分为4组,每组6个重复,每重复12只鸡.对照组饲喂基础日粮,试验组分别于基础日粮中添加1、2、4 mg/kg地克珠利,试验期49 d.结果表明,基础日粮中添加1～4 mg/kg地克珠利对肉鸡生长性能和屠宰性能均无显著影响(P＞0.05);1 mg/kg地克珠利组肉鸡免疫器官指数、新城疫抗体效价和外周血T淋巴细胞转化率与对照组均无显著差异(P＞0.05),2、4 mg/kg组外周血T淋巴细胞转化率显著低于对照组(P＜0.05或P＜0.01),4mg/kg组肉鸡于28日龄免疫器官指数显著高于对照组(P＜0.05),血清新城疫抗体效价显著低于对照组(P＜0.05);肉鸡血清淀粉酶活性,2、4 mg/kg组于28、35(停药0d)、42日龄(停药7d)显著低于对照组和1 mg/kg组(P＜0.05或P＜0.01);3个试验组血清总蛋白含量于28、35(停药0d)、42日龄(停药7d)均显著或极显著(P＜0.05或P＜0.01)高于对照组;血清总超氧化物歧化酶活性,2、4 mg/kg组于28日龄显著或极显著(P＜0.05或P＜0.01)高于对照组和1 mg/kg组;4 mg/kg组于35日龄(停药0d)和42日龄(停药7d)显著低于对照组和其他2个试验组(P＜0.05或P＜0.01);血清葡萄糖含量各组间均差异不显著(P＞0.05).49日龄(停药14 d)各组间上述血清生化指标差异均不显著(P＞0.05).相关分析表明,血清总蛋白含量和葡萄糖含量与平均日增重间存在着极显著的正相关关系(P＜0.01),总超氧化物歧化酶活性与平均日增重间存在着极显著的负相关关系(P＜0.01).     

植物精油和有机酸对肉鸡生长性能、肠道形态结构和血清指标的影响

试验旨在研究植物精油和有机酸对肉鸡生长性能、肠道形态结构、血清生化指标及新城疫(ND)抗体效价的影响。选取1 008只1日龄体重相近的健康科宝肉鸡,随机分成3组,每组6个重复,每个重复56只(各重复公母比例一致)。对照组饲喂玉米-豆粕型基础饲粮,抗生素组在基础饲粮中添加20 mg/kg的维吉尼亚霉素,试验组在基础饲粮中添加100 mg/kg复合植物精油和900 mg/kg复合有机酸,试验周期42 d。结果表明：(1)在1～42日龄时,试验组的料重比(F/G)极显著低于对照组和抗生素组(P<0.01),平均日采食量(ADFI)显著低于抗生素组(P<0.05)。(2)与对照组相比：试验组42日龄的十二指肠绒毛高度显著升高(P<0.05)、绒隐比(V/C)极显著提高(P<0.01);试验组空肠的绒毛高度在各阶段均显著升高(P<0.05),且在42日龄时,隐窝深度极显著降低(P<0.01)、V/C极显著提高(P<0.01);试验组回肠的绒毛高度和V/C在各阶段均极显著升高(P<0.01),隐窝深度在14和42日龄时均极显著降低(P<0.01...     

纳豆芽孢杆菌对肉仔鸡生长性能、免疫功能及肠道健康的影响北大核心

试验旨在研究饲喂纳豆芽孢杆菌(Bacillis natto)对肉仔鸡生长性能、免疫功能及肠道菌群的影响。选取180只1日龄科宝肉仔鸡,随机分为2组,每组6个重复,每个重复15只鸡,对照组肉鸡饲喂基础日粮,试验组肉鸡饲喂基础日粮+300 mg/kg纳豆芽孢杆菌。试验期42 d。结果显示,与对照组相比,1~42日龄试验组肉鸡的平均日增重显著提高(P<0.05),肉鸡42日龄体重显著提高(P<0.05)。与对照组相比,21日龄和42日龄试验组肉鸡血清免疫球蛋白M (IgM)含量分别提高了37.63%、38.85%(P<0.01);42日龄试验组肉鸡空肠黏膜白细胞介素-1β (IL-1β)含量极显著降低(P<0.01)。基于PCoA分析结果显示,试验组肉鸡肠道菌群结构发生改变,与对照组相比,试验组肉鸡肠道另枝菌属(Alistipes)占比有所提高(P>0.05),试验组的Enorma、未分类_f_黄杆菌属(norank_f_Flavobacteriaceae)、Paludicola显著升高(P<0.05)。研究表明,纳豆芽孢杆菌能够改善肠道菌群结构,提高肠道菌群丰富度和多样性,增强机体免疫功能,进而提高肉仔鸡生长性能。     

微生态制剂对肉鸡体液免疫和细胞免疫的影响

将微生态制剂添加到肉鸡的饲料中,通过检测肉鸡血清中ND血凝抑制抗体效价、红细胞花环率及免疫器官中T细胞百分数等指标,探讨该制剂对肉鸡体液免疫和细胞免疫的影响。结果表明:在17、26、35、49日龄时,试验组血清中ND血凝抑制抗体效价分别比对照组高8.65%、26.98%、19.83%和46.91%,差异显著(P<0.05);在21日龄,试验组的E-C3bR率和E-ICR率分别比对照组高16.24%和19.93%,均差异显著(P<0.05);10、17日龄时,试验组胸腺T细胞百分数分别比对照组高13.01%(P<0.05)和6.41%(P<0.05),脾脏T细胞百分数分别比对照组高19.40%和9.17%,差异显著(P<0.05)。     

多肽菌素对肉鸡血清生化指标、血清抗体水平及免疫器官指数的影响

试验旨在研究多肽菌素对肉鸡血清生化指标、血清抗体水平及免疫器官指数的影响,以验证多肽菌素提高肉鸡机体免疫力的能力。4万只1日龄科宝500肉雏鸡随机分为2组,即试验组和对照组,每组4个重复,每个重复5 000只。对照组按原有免疫和用药程序7日龄、14日龄及21日龄均进行新城疫和禽流感疫苗免疫;试验组鸡只在7日龄时进行新城疫和禽流感疫苗免疫,并在13~15日龄饲喂添加多肽菌素(400 g/t)的日粮,20~22日龄饲喂添加多肽菌素(300 g/t)的日粮。试验期28 d。结果显示:试验组28日龄肉鸡血清总蛋白含量、球蛋白含量、球蛋白与白蛋白比值(球/白)分别比对照组提高10.75%、15.17%、11.45%,谷草转氨酶活性比对照组提高6.23%,差异显著(P0.05);试验组肉鸡新城疫病毒抗体效价比对照组提高19.89%,差异显著(P0.05),禽流感病毒抗体效价比对照组提高6.97%,差异显著(P0.05);试验组肉鸡脾脏指数比对照组提高17.05%,差异显著(P0.05),试验组胸腺指数比对照组提高11.89%,差异显著(P0.05)。研究表明:肉鸡日粮添加多肽菌素,可以显著改善血清生化指标,提高机体抗体水平及免疫器官指数。     

牛磺酸对蛋鸡脂质代谢的影响

将108只60周龄蛋用母鸡随机分为4组。每组3个重复,每个重复9只鸡。试验组Ⅰ、Ⅱ、Ⅲ分别加入50mg/kg、100mg/kg、200mg/kg 牛磺酸,对照组不加牛磺酸。结果表明,与对照组相比,试验组Ⅰ、Ⅱ、Ⅲ血清甘油三脂分别下降10．06％、13．03％、13．97％,差异极显著 (P<0．01);试验组Ⅰ、Ⅱ、Ⅲ血清总胆固醇分别下降9．95％、10．65％、 10．45％,差异极显著;血清高密度脂蛋白胆固醇,试验组Ⅰ下降 20．83％,差异显著(P<0．05);试验组Ⅱ、Ⅲ下降33．33％、29．19％,差异极显著(P<0．01);蛋黄总胆固醇,试验组Ⅰ下降3．17％,差异显著 (P<0．05);试验组Ⅱ、Ⅲ下降5．25％、6．76％,差异极显著(P<0．01)。     

烟曲霉菌感染对雏鸡免疫器官指数及新城疫抗体水平的影响

为了研究烟曲霉菌感染对雏鸡免疫器官指数及新城疫抗体水平的影响,试验选取40只14日龄海兰褐公鸡,随机分成2组,每组20只,试验组用霉菌孢子攻毒3 d,对照组不攻毒,所有试验鸡均按常规模式进行饲养和防疫,并于攻毒后第5天从试验组和对照组中各选10只鸡进行免疫器官指数的测定和血清中新城疫病毒抗体效价测定。结果表明:试验组雏鸡体重降低,法氏囊、胸腺重及法氏囊指数、胸腺指数均低于对照组且差异显著(P0.05);脾脏重和脾脏指数与对照组相比差异不显著(P0.05);试验组雏鸡新城疫血清抗体效价低于对照组,且差异显著(P0.05)。说明烟曲霉菌感染能造成雏鸡免疫抑制,导致免疫器官萎缩、变小,使免疫机能下降,影响疫苗免疫效果。     

L-茶氨酸对黄羽肉鸡生产性能和免疫功能的影响

本试验旨在探讨L-茶氨酸对黄羽肉鸡生产性能和免疫功能的影响。选用1日龄黄羽肉鸡690只,随机分为6个处理,每个处理5个重复,每个重复23只。6个处理分别为对照组(饲喂无抗生素基础饲粮)、抗生素组[饲喂在基础饲粮中添加10%硫酸黏杆菌素的饲粮,前期(1～3周)添加200 mg/kg,后期(4～7周)添加150 mg/kg]、4个不同梯度(100、200、400和800mg/kg)L-茶氨酸试验组,试验期为49 d。试验检测了黄羽肉鸡的生产性能、免疫器官指数、肠道分泌性免疫球蛋白A(sIgA)含量及血清溶菌酶活性、抗体水平和免疫细胞因子含量等指标。结果表明:在试验前期,100 mg/kg L-茶氨酸组黄羽肉鸡的体增重显著低于其他各组(P<0.05),100、200和800 mg/kg L-茶氨酸组黄羽肉鸡的法氏囊指数显著低于对照组(P<0.05),各L-茶氨酸组黄羽肉鸡的肠道sIgA含量和血清干扰素-γ(IFN-γ)含量显著高于对照组(P<0.05)。在试验后期,与对照组及抗生素组比较,L-茶氨酸对黄羽肉鸡生产性能、免疫器官指数、肠道sIgA的含量影响不显著(P>0.05);100、200和400 mg/kg L-茶氨酸组黄羽肉鸡血清白细胞介素-2(IL-2)的含量显著高于对照组(P<0.05),200和400 mg/kg L-茶氨酸组黄羽肉鸡血清IFN-γ的含量显著高于对照组(P<0.05)。在整个试验期,各组黄羽肉鸡血清溶菌酶的活性和白细胞介素-4的含量差异不显著(P>0.05);一免后第6天,100和200 mg/kg L-茶氨酸组黄羽肉鸡血清新城疫抗体滴度显著低于对照组和抗生素组(P<0.05),一免后第14天,100、200和400 mg/kg L-茶氨酸组黄羽肉鸡抗牛血清白蛋白(BSA)抗体水平显著高于对照组(P<0.05),其他各阶段各组间的抗BSA抗体水平和新城疫抗体滴度均差异不显著(P>0.05)。由此可知,饲粮添加L-茶氨酸对黄羽肉鸡生长后期生产性能、免疫器官指数均无显著影响,说明其对黄羽肉鸡后期生长是安全的;同时L-茶氨酸可提高黄羽肉鸡生长前期肠道sIgA的含量、后期血清IL-2的含量及全期血清IFN-γ的含量,从而增强其机体免疫功能。     

复合微生态制剂对肉鸡生长性能和免疫性能的影响

该试验通过将微生态制剂产品倍利素添加到肉鸡的饮水中,研究其对肉鸡生长性能和免疫性能的影响。试验选用150只1日龄健康AA肉鸡,随机分为2组,其中一组为对照组,另一组为试验组,每组3个重复,每个重复25只鸡。预饲期4d,正式期36d。结果表明:在12、19、26、40日龄时检测发现,试验组与对照组相比,料肉比下降,均差异显著(P<0.05),且在整个试验周期内,试验组比对照组料肉比下降10.9%,差异显著(P<0.05)。33日龄时检测发现,试验组的脾脏指数比对照组高出55.1%,差异显著(P<0.05)。26日龄时检测发现,试验组的法氏囊指数比对照组高出65.7%,差异显著(P<0.05)。12、19、26、33和40日龄时检测发现,试验组血清中新城疫血凝抑制抗体效价分别比对照组高出36.6%、40.4%(P<0.05)、37.7%、34.7%和38.8%;试验组盲肠内容物中分泌型IgA含量分别比对照组高出8.59%、10.6%、22.8%、68.7%、23.2%,均差异显著(P<0.05)。19、33、40日龄时检测发现,试验组血清中IgG分别比对照组高出17.9%(P<0.05)、40.9%(P<0.01)、41.1%(P<0.01)。19日龄时检测发现,试验组的E-C3bR、E-ICR花环率分别比对照组提高了105.9%(P<0.05)、14.3%(P>0.05);而在26、33日龄时检测发现,试验组的E-C3bR、E-ICR花环率与对照组相比,差异均不显著(P>0.05)。由此可知,倍利素能够提高肉鸡的生长性能,同时可以在一定程度上增强肉鸡的免疫功能。     

四君子汤加减颗粒对腹腔巨噬细胞吞噬功能及ND和IBD疫苗免疫效果的影响

为探讨四君子汤加减颗粒对小鼠腹腔巨噬细胞吞噬功能和肉用仔鸡免疫鸡新城疫(ND)疫苗、传染性囊病(IBD)疫苗后血清ND及IBD抗体效价的影响,选取40只小鼠,随机分为4组,对照组正常饮水,试验组在饮水中添加不同浓度的四君子汤加减颗粒,测定各组腹腔巨噬细胞吞噬百分率和吞噬指数;同时以肉用仔鸡为研究对象,考察四君子汤加减颗粒分别与ND Clone-30疫苗、ND油乳剂灭活苗和IBD冻干苗合用之后,肉用仔鸡血清中ND、IBD抗体效价的变化情况。结果显示,试验组小鼠的腹腔巨噬细胞吞噬百分率和吞噬指数均显著高于对照组(P<0.05);试验组鸡血清中的ND和IBD抗体效价均高于对照组。表明四君子汤加减颗粒可显著提高小鼠腹腔巨噬细胞的吞噬活性并能显著增强ND、IBD疫苗对肉用仔鸡的免疫效果。     

Dose-related antinociceptive effects of intravenous buprenorphine in cats

The dose-related antinociceptive effects of intravenous (IV) buprenorphine were evaluated in cats. Thermal (TT) and mechanical threshold (MT) devices were used for nociceptive stimulation. After baseline threshold recordings, buprenorphine was administered IV (0.01, 0.02 or 0.04 mg/kg; B1, B2 and B4, respectively) in a randomised, blinded and cross-over study. Data were analysed by ANOVA (P < 0.05) using 95% confidence intervals (CI). TT increased 15, 30, 45 min and 1 (5.2 ± 2.7 °C), 2, 3 and 4 h after B1; 15, 30, 45 min and 1 (5.1 ± 3.9 °C) and 2 h after B2, and 15, 30, 45 min and 1 (5.4 ± 3.3 °C), 2, 3, 6 and 8 h after B4. MT increased 15 and 45 min after B2 (260 ± 171 mmHg), and 30 (209 ± 116 mmHg) and 45 min and 1 and 2 h after B4. At 45 min, MT values were significantly higher after B2 compared to B1 (P < 0.05). With MT, B2 and B4 produced more antinociception and longer duration of action than B1, respectively. No dose response to thermal stimulation was detected.     

Effect of storage duration on egg quality,embryo mortality and hatchability in FUNAAB-ɑ chickens

Effect of extended storage on egg quality, embryo mortality and hatchability in FUNAAB-ɑ chickens was determined. Hatchable eggs (n = 288; weighing 53.2 ± 4.67 g) collected from a flock of FUNAAB-ɑ layer breeder hens aged 32 weeks were stored in egg tray with broad end up under 16 ± 1.5°C for either 0, 4, 8, 12, 16 or 20 d. Before incubation, eight eggs from each group were evaluated for internal and external quality traits. Remaining eggs were set in an incubator and transferred into hatcher on embryonic day 18. Data collected were subjected to one-way analysis of variance. Egg weight loss (EWL; p < .001), surface area (p < .001), yolk diameter (p < .001), inner and outer blastoderm diameters (p < .05) and dead in germ (DIG; p < .001) increased with storage duration while yolk height (p < .001), yolk index (p < .001), albumen weight (p < .05), albumen height (p < .05), albumen index (p < .01), Haugh's unit (HU; p < .05), fertility (p < .001), hatchability of set (HATCHS; p < .001) and fertile eggs (p < .05) decreased. Weight losses of 0, 1.2, 2.2, 3.4, 4.6 and 6.1% were recorded in egg stored for 0, 4, 8, 12, 16 and 20 days respectively. Eggs stored beyond 8 days exhibited higher DIG and lower HATCHS. Shell percentage in 4 days storage (11.4%) was lower (p < .05) than in 16 days storage (13.4%). Shell thickness was similar in eggs stored for 0 to 12 days, but 8 days storage (0.60 mm) had thinner (p < .01) shell than day 16 (0.71 mm) and day 20 (0.73 mm) storage. Internal quality unit (IQU) was higher (p < .05) in fresh eggs (180.4) than in 12 days (167.8) and 20 days (167.8) stored eggs. Extended storage of FUNAAB-ɑ eggs caused EWL, surface area shrinkage, lowered HU and IQU, loss of yolk and albumen quality, increased blastoderm diameters and DIG, and decreased egg fertility and HATCHS from day 8 forward. Storing FUNAAB-ɑ eggs beyond 8 days reduced quality parameters; therefore, other mitigating factors are recommended when storing beyond 8 days.     

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.     

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.     

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.     

Influence of dietary lysine level on whole-body protein turnover, plasma IGF-I, GH and insulin concentration in growing pigs

Four growing pigs (initial liveweight 25.9 ± 0.54 kg, final liveweight 43.0 ± 1.06 kg) were used to study the effect of dietary lysine level on nutrient digestibility, whole-body protein turnover, plasma insulin-like growth factor-I (IGF-I), growth hormone (GH), insulin, glucose, and urea nitrogen (PUN). Four diets, containing 7.0 g (L1), 9.5 g (L2), 12.0 g (L3) and 14.5 g (L4) lysine per kg diet respectively, were formulated as experimental treatments. The animals and diets were allocated in a 4 × 4 Latin square design. Nitrogen (N) metabolism and whole-body protein turnover were measured by classical method and single-dose ¹⁵N end-product method, respectively. The blood samples were taken at the end of each experimental period. Results showed that N retention (NR) and N biological value (NBV) were significantly increased from L1 to L4 (P < 0.05). However, differences in NR and NBV between L2, L3 and L4 were not significant (P > 0.05). There was no significant difference on dry matter (DM) digestibility, organic matter (OM) digestibility and N digestibility between different treatments (P > 0.05). Whole-body protein synthesis, protein degradation and protein accretion increased markedly from L1 to L2 (P < 0.05), but did not increase further from L2 to L4. Whole-body protein accretion (y, g/kg W^0.75/d) increased with dietary lysine (x, g/kg) in a quadratic manner: y = − 0.09x² + 2.12x − 5.14 (r² = 0.96, n = 4, P < 0.05).The results also showed that differences in plasma IGF-I, GH, glucose and PUN concentration between different treatments were not significant (P > 0.05). Plasma insulin concentration (y, μIU/ml) was increased with dietary lysine (x, g/kg) in a quadratic manner: y = 0.23x² − 4.10x + 32.25 (r² = 0.99, n = 4, P < 0.05), but it was not found that plasma insulin concentration was related to NR. A significant correlation was found between NR (y, g/d) and plasma IGF-I (x, ng/ml): y = − 3.1 × 10^− 3x² + 1.31x − 122.28 (r² = 0.99, n = 4, P < 0.05).It was concluded that dietary lysine level had a significant influence on NR and whole-body protein turnover but not on plasma IGF-I and GH concentration. Plasma IGF-I may be an important factor controlling N metabolism of growing pigs. Further research was needed to study the mechanism.     

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.     

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.     

Efficacy of a mephentermine‐based product as a vasopressor and a cardiac performance enhancer when given intramuscularly to cattle

The goal of this study was to confirm the vasopressor and cardiac effects of POTENAY^® INJETÁVEL (POT), a mephentermine‐based product, given to cattle with induced vascular/cardiac depression. Ten healthy Holstein cattle (206 ± 13 kg) followed a randomized‐complete‐block design (RCBD) utilizing crossover study design. Each animal randomly received (1 ml/25 kg, IM) of either POT (n = 10) or volume‐matched placebo control (0.9%NaCl, CP, n = 10). A subset of animals (n = 5) received POT first (day 0) while the remaining (n = 5) received CP; after a six‐day washout period, cattle received the opposite compound. Animals were anesthetized and catheterized for systemic/left ventricular hemodynamic monitoring. Myocardial dysfunction/hypotension was induced by increasing the end‐tidal isoflurane concentration until arterial blood pressure was 20% lower than at baseline and remained stable. Once the animal was determined to be hypotensive and hemodynamically stable, steady‐state hypotensive baseline data (BL2) were acquired, and treatment with either POT or CP was given. Data were acquired post‐treatment at every 15 min for 90 min. POT improved cardiac output (+68 L/min, ±14%, p < 0.05), MAP (+14 mmHg, ±4%, p < 0.05), HR (+22 bpm, ±8%, p < 0.05), and peak rates of ventricular pressure change during both systole (dP/dt_max: +37 mmHg/s ±13%, p < 0.05) and diastole (dP/dt_min: +31 mmHg/s, ±7%, p < 0.05). No improvements were noted following placebo‐control administration. Results indicate that POT improves cardiac performance and systemic hemodynamics in cattle with induced cardiovascular depression when given as single intramuscular injection.     

Cardiopulmonary and sedative effects of intravenous or epidural methadone in conscious dogs

Cardiopulmonary and sedative effects of intravenous or epidural methadone were compared. Six beagles were randomly assigned to group MIV (methadone 0.5 mg/kg IV + NaCl 0.9% epidurally) or MEP (methadone 0.5 mg/kg epidurally + NaCl 0.9% IV). Cardiopulmonary, blood gas and sedation were assessed at time (T) 0, 15, 30, 60, 120, 240 and 480 min after drug administration. Compared to T0, heart rate decreased at T15–T120 in MIV (p < .001) and T15–T240 in MEP (p < .05); mean arterial pressure was reduced at T15–T60 in MEP (p < .01); respiratory rate was higher at T15 and T30 in both groups (p < .05); pH was lower at T15–T120 in MIV (p < .01) and T15, T30 and T120 in MEP (p < .05); PaCO₂ was higher at T15–T60 in MIV (p < .01) and T15, T30 and T120 in MEP (p < .01); sedation scores were higher at T15 and T30 in MIV and T15–T60 in MEP (p < .05). At T120 and T240, sedation score was higher in group MEP compared with group MIV (p < .01) In conclusion, cardiopulmonary and sedative effects of identical methadone doses are similar when administered IV or epidurally to conscious healthy dogs.