皮下埋植褪黑激素对獭兔免疫器官、性腺发育和生长性能的影响

选用60只110日龄的獭兔分成3组,分别给予皮下不埋植和埋植8、16mg组褪黑激素,测定110日龄獭兔免疫器官发育、性腺发育、生长性能和被毛密度的指标。结果表明:皮下埋植褪黑激素对獭兔免疫器官、性腺发育和生长性能的影响均不显著(P>0.05),但能显著增加(P<0.05)獭兔的被毛密度。     

饲粮泛酸添加水平对冬毛生长期水貂生产性能、血清生化指标及毛囊发育的影响

本试验旨在研究饲粮泛酸添加水平对冬毛生长期水貂生产性能、血清生化指标及毛囊发育的影响。采用单因子试验设计,选用(140±5)日龄、平均体重(1.94±0.19)kg的健康雄性短毛黑水貂60只,随机分成6组,每组10个重复,每个重复1只。基础饲粮中泛酸含量为8.91 mg/kg,各组饲粮泛酸添加水平分别为0(Ⅰ组,对照组)、10(Ⅱ组)、20(Ⅲ组)、30(Ⅳ组)、40(Ⅴ组)、80 mg/kg(Ⅵ组)。预试期5 d,正试期65 d。结果表明:1)Ⅵ组水貂鲜皮重显著高于Ⅰ~Ⅳ组(P<0.05)。2)随着饲粮泛酸添加水平的增加,Ⅰ~Ⅴ组血清泛酸含量逐渐增加,但差异不显著(P>0.05),Ⅵ组血清泛酸含量显著高于其他各组(P<0.05);各组之间肝脏泛酸含量差异不显著(P>0.05)。3)Ⅲ组血清球蛋白(GLOB)含量显著高于Ⅰ、Ⅱ和Ⅴ组(P<0.05),Ⅲ组血清胆固醇(CHO)和高密度脂蛋白胆固醇(HDL-C)含量极显著低于Ⅴ和Ⅵ组(P<0.05)。4)Ⅱ组冬毛生长前期血清褪黑激素含量显著低于Ⅰ组(P<0.05),Ⅲ组显著高于Ⅱ组(P<0.01),Ⅳ、Ⅴ、Ⅵ组极显著低于Ⅲ组(P<0.01)。Ⅲ组冬毛生长后期血清褪黑激素含量显著低于其他各组(P<0.05)。5)Ⅵ组毛囊深度显著高于Ⅳ组(P<0.05),极显著高于Ⅰ组(P<0.01);各组毛囊密度和次级毛囊密度/初级毛囊密度无显著差异(P>0.05)。综上所述,饲粮泛酸添加水平为20 mg/kg时(饲粮中总泛酸含量为28.91 mg/kg),水貂皮长增加2.37%,同时增加了血清GLOB含量,降低了血清CHO和HDL-C含量;饲粮泛酸添加水平为80 mg/kg时(饲粮中总泛酸含量为88.91 mg/kg),降低了水貂冬毛生长前期血清褪黑激素含量,增加了毛囊深度,增加了水貂鲜皮重。     

褪黑激素对獭兔日增重及其毛皮皮尺的影响

选取体重为1.4kg左右日龄相近的健康獭兔60只,随机分为3组,每组20只,公母各半。分别皮下埋植褪黑激素0mg、10mg、20mg,研究褪黑激素对獭兔日增重及其毛皮皮尺的影响。结果表明:褪黑激素对獭兔的日增重增加4.1%(P>0.05)、毛皮长度以及毛皮厚度均无显著(P>0.05)影响;但埋植10mg组的獭兔毛皮宽度要显著(P<0.05)大于埋植20mg组。     

藏西北绒山羊羔羊埋植褪黑激素对其周岁产绒性能和毛囊发育的影响

为研究埋植褪黑激素对藏西北绒山羊周岁羔羊产绒性能和毛囊发育的影响,选取1日龄体况相近的绒山羊羔羊30只,随机分为2组,每组15只。对照组羔羊不做任何处理,试验组羔羊分别于15、75和135日龄埋植褪黑激素(剂量为2 mg/kg BW)。记录羊只周岁抓绒前的体重,抓绒时记录产绒量,并采集绒毛和皮肤样品,分析羊绒长度、细度及毛囊发育情况。结果表明,褪黑激素对周岁羊抓绒前体重和绒毛细度没有显著影响(P0.05),但能极显著提高其产绒量和绒毛长度(P0.01);褪黑激素对周岁羊初级毛囊密度和成熟次级毛囊密度没有显著影响(P0.05),但能极显著地提高其次级毛囊密度、次级毛囊与初级毛囊数目比和成熟次级毛囊与初级毛囊数目比(P0.01)。说明藏西北绒山羊羔羊埋植褪黑激素能够促进其周岁时的毛囊发育,提升产绒性能。     

褪黑激素对长毛兔产毛性能及兔毛品质的影响

试验旨在研究褪黑激素(Melatonin,MT)对长毛兔夏季产毛的影响。选择1.5岁左右的皖系长毛兔60只,其中公兔40只,母兔20只,随机分为4组,分别皮下埋植0、25、40、55 mg的褪黑激素,经过70 d的养毛期后测定各组产毛量及粗毛和细毛的长度变化差异,分析褪黑激素对长毛兔产毛性能的影响。结果显示:公兔40 mg埋植组产毛量显著高于埋植前产毛量(P<0.05),55 mg埋植组产毛量显著高于对照组产毛量(P<0.05);母兔对照组试验后剪毛量显著低于试验前剪毛量(331.0 g vs 284.8 g,P<0.05),而3个褪黑激素埋植组试验后产毛量下降幅度并不显著(P>0.05)。皮下埋植40 mg或55 mg褪黑激素能够增加皖系长毛兔公兔或母兔的粗毛长度,但对细毛长度和兔毛细度均无显著影响(P>0.05)。说明长毛兔皮下埋植40 mg和55 mg褪黑激素能够提高公兔夏季产毛量且抑制母兔夏季产毛量的降低,同时增加公、母兔粗毛长度。研究结果可为褪黑激素的合理利用提供参考,并为揭示其对促进长毛兔夏季兔毛生长的作用机制奠定基础。     

不同光照和褪黑激素对獭兔生产性能和营养物质利用率的影响

选取4月龄体重相近的健康獭兔96只随机分成12组,每组8只,采用3×4随机区组试验设计,研究不同光照和褪黑激素对獭兔生产性能和营养物质利用率的影响。结果表明:①不同光照及褪黑激素对獭兔平均日增重均有显著(P<0.05)或极显著(P<0.01)影响,光照与褪黑激素对獭兔平均日增重存在显著互作效应(P<0.05);②不同光照对獭兔粗蛋白消化率、粗脂肪消化率无显著影响(P>0.05),褪黑激素对獭兔粗蛋白消化率、粗脂肪消化率有极显著影响(P<0.01),光照与褪黑激素对獭兔粗蛋白消化率存在显著互作效应(P<0.05);③不同光照对獭兔血清GH无显著影响(P>0.05),褪黑激素对獭兔血清GH有极显著影响(P<0.01),光照与褪黑激素对獭兔血清GH存在显著互作效应(P<0.05);不同光照及褪黑激素对獭兔血清TP均有显著影响(P<0.05),光照与褪黑激素对獭兔血清TP无显著互作效应(P>0.05);不同光照对獭兔血清BUN无显著影响(P>0.05),褪黑激素对獭兔血清BUN有显著影响(P<0.05),光照与褪黑激素对獭兔血清BUN无显著互作效应(P>0.05)。本研究结果显示,褪黑激素能提高獭兔生产性能和各种营养物质的消化率,建议在獭兔生产中采取自然光照条件下饲喂36 mg/只褪黑激素。     

不同饲喂模式对生长獭兔生产性能的影响

选择同期断奶的生长獭兔180只,随机分成3组,日粮分别按NRC饲养标准(Ⅰ组)、克里莫饲养标准(Ⅱ组)、一料到底饲养标准(Ⅲ组)3个饲喂模式的营养水平配制,观察其对仔兔生长发育、营养物质消化率、被毛品质的影响。结果表明:仔兔90日龄的末重和平均日增重Ⅰ组显著高于Ⅱ组6.41%(P<0.05);平均日耗料量Ⅰ组、Ⅲ组分别比Ⅱ组高10.85%、10.31%,差异均极显著(P<0.01);耗料增重比Ⅲ组比Ⅰ组、Ⅱ组分别高4.58%、4.89%,差异均极显著(P<0.01);营养物质的消化率,Ⅲ组显著低于Ⅰ组、Ⅱ组(P<0.05);被毛品质中,被毛密度Ⅲ组极显著高于Ⅱ组14.99%(P<0.01),被毛长度各组差异不显著(P>0.05)。     

光照和褪黑激素对獭兔毛皮品质的影响

选取4月龄体质量相近的96只健康獭兔,随机分为12组,每组8只兔,试验采用3×4因子设计,分别进行不同光照(长光照、自然光照和短光照)和褪黑激素(0、12、24和36 mg/kg)处理,试验期为49 d。研究光照和褪黑激素对獭兔毛皮品质的影响,结果表明:1)光照和褪黑激素对獭兔被毛密度有极显著影响;光照对獭兔皮张面积有显著影响,褪黑激素对獭兔皮张面积有极显著影响。2)光照和褪黑激素对獭兔被毛密度无显著互作效应,对獭兔皮张面积存在显著互作效应。3)综合各种指标,为达到最大的经济效益,建议采取自然光照条件下饲喂36 mg/kg褪黑激素。     

光照和日粮能量干预对绒山羊消化率、毛囊活性和产绒性能的影响

试验研究光照和日粮能量干预对内蒙古白绒山羊营养物质表观消化率、毛囊活性和产绒性能的影响。选择体况良好,体重为(20.36±2.63)kg的2周岁内蒙古白绒山羊24只,随机分为4组,每组6只,分别为高能量自然光照组(Ⅰ)、高能量短光照组(Ⅱ)、低能量自然光照组(Ⅲ)和低能量短光照组(Ⅳ),进行5个月的光照控制饲喂试验。结果表明,7月份Ⅳ组次级毛囊活性显著高于Ⅰ组(P0.05),Ⅱ组和Ⅳ组试验羊的CP消化率显著高于Ⅰ组和Ⅲ组(P0.05);9月份Ⅳ组试验羊的DM表观消化率显著高于Ⅲ组(P0.05),Ⅲ组的NDF和CP表观消化率显著低于Ⅳ组和Ⅰ组(P0.05),Ⅱ组次级毛囊活性显著高于其他三个组(P0.05);10月份,Ⅰ组试验羊平均体重显著高于Ⅳ组(P0.05),Ⅱ组和Ⅳ组试验羊的CP消化率显著高于Ⅰ组和Ⅲ组(P0.05),Ⅳ组次级毛囊活性显著高于Ⅱ组(P0.05),Ⅱ组和Ⅳ组试验羊的平均绒长度均显著高于Ⅰ组和Ⅲ组(P0.05);Ⅳ组试验羊的平均绒细度显著低于Ⅰ组(P0.05);Ⅲ组试验羊的平均绒重量显著低于Ⅱ组(P0.05)。在本试验条件下,相同光照时间高能量组试验羊平均体重提高6.98%,绒细度增加;相同能量水平短光照组试验羊的DM、NDF和CP表观消化率显著提高,皮肤次级毛囊活性,绒长度和绒重量显著提高。     

饲粮肌醇添加水平对2～4月龄生长獭兔生长性能、毛皮质量、免疫器官指数和营养物质利用率的影响

本试验旨在研究饲粮肌醇添加水平对2~4月龄生长獭兔生长性能、毛皮质量、免疫器官指数和营养物质利用率的影响。选取体重相近的2月龄生长獭兔88只,随机分成4组,每组22个重复,每个重复1只。Ⅰ组为对照组,饲喂基础饲粮,Ⅱ组、Ⅲ组、Ⅳ组为试验组,分别饲喂在基础饲粮中添加25、50、75 mg/kg肌醇的试验饲粮。试验期为60 d。结果表明:1)饲粮肌醇添加水平对生长獭兔平均日增重和料重比无显著影响(P0.05)。2)饲粮肌醇添加水平对生长獭兔毛皮面积、毛皮重量无显著影响(P0.05),但对被毛密度、被毛长度有显著或极显著影响(P0.05或P0.01)。被毛长度以Ⅲ组最长,显著长于Ⅰ组(P0.05),但与Ⅳ组无显著差异(P0.05);被毛密度以Ⅳ组最大,极显著大于Ⅰ组和Ⅲ组(P0.01),显著大于Ⅱ组(P0.05)。3)饲粮肌醇添加水平对生长獭兔脾脏指数无显著影响(P0.05),胸腺指数随着肌醇添加水平的提高呈升高趋势(P0.05)。4)饲粮肌醇添加水平对生长獭兔粗纤维、中性洗涤纤维、酸性洗涤纤维利用率无显著影响(P0.05),但对干物质、总能、粗蛋白质利用率有显著或极显著影响(P0.05或P0.01)。其中,干物质利用率以Ⅳ组最高,显著高于Ⅰ组(P0.05);Ⅱ组的总能利用率显著高于Ⅰ组(P0.05),Ⅳ组的总能利用率极显著高于Ⅰ组(P0.01);Ⅱ组和Ⅳ组的粗蛋白质利用率显著高于Ⅰ组(P0.05),Ⅲ组的粗蛋白质利用率极显著高于Ⅰ组(P0.01)。综合以上测定指标,在生长獭兔饲粮中适宜的肌醇添加水平为75 mg/kg。     

Antimicrobial susceptibility of Moraxella bovis

The antimicrobial susceptibility of 55 isolates of Moraxella bovis to seven antibiotics was evaluated by broth microdilution procedures. The isolates had an MIC₉₀ of ≤1 mg/l to erythromycin, ceftiofur, and ampicillin; 4 mg/l to tilmicosin; 16 mg/l to tylosin and gentamicin; and had MIC₉₀s of ≥32 mg/l for oxytetracycline. The modal MIC values for these antibiotics were as follows: ampicillin, <0.25 mg/l; ceftiofur, ≤0.125 mg/l; tilmicosin, 2 mg/l; tylosin, 8 mg/l; erythromycin 1 mg/l; oxytetracycline, ≤0.5 mg/l; and gentamicin, ≤0.5 mg/l. This in vitro data showed most antibiotics have low MICs that are suggestive of clinical efficacy.     

Pharmacokinetics of total thyroxine in dogs after administration of an oral solution of levothyroxine sodium

Oral l -thyroxine ( l -T4) supplementation is used to replace thyroid hormone concentrations in dogs with hypothyroidism. The pharmacokinetics of l -T4 following administration of a solution (Leventa^®) was investigated in healthy dogs. l -T4 was absorbed fairly rapidly ( t _max 3 h). A mean bioavailability of 22% was calculated following a single oral administration of 40 μg l -T4/kg body weight. Repeated oral administration at the same dose for 14 consecutive days did not lead to any accumulation of T4 in serum. After intravenous administration of l -T4, a serum half-life of 11.6 h was calculated. Food intake concomitant with l -T4 oral administration delayed l -T4 absorption and decreased its rate and extent by about 45%. The relative bioavailability of l -T4 following administration of a tablet formulation was about 50% of that of the l -T4 solution. The pharmacokinetic properties of liquid l -T4 after oral administration support the use of a dose rate of 20 μg/kg once daily, as a starting dose for replacement therapy in dogs with hypothyroidism.     

Application of the ASVCP guidelines for the establishment of haematologic and biochemical reference intervals in Icelandic horses in Austria

Background

Despite the increasing popularity of Icelandic horses, published reference intervals (RIs) in this breed are rare. Due to their isolation and their small gene pool, alterations in some variables are likely and some possible breed-specific peculiarities have been described. The purpose of the present study was the establishment of comprehensive RIs in Icelandic horses according to recently published guidelines.In a prospective observational study, blood samples were collected from the jugular vein of 142 Icelandic horses into EDTA and serum tubes. Reference intervals were established for haematologic and biochemical analytes on the Advia 2120i™ and the Dimension ExL™ by established methods. RIs were defined as central 95 % intervals bounded by the 2.5th and 97.5th percentiles with their 90 % confidence intervals, calculated according to recently published ASVCP guidelines. An inhouse-developed quality control system using observed total allowable error was used for the surveillance of the internal quality control preceding the measurements.

Results

The RIs were as follows: haematocrit: 0.29–0.39, RBC: 5.79–8.63 T/l, haemoglobin: 102.0–142.3 g/l, MCV: 42–51 fl, platelets: 146–263 G/l, WBC: 4.13–8.57 G/l, segs: 1.98–4.73 G/l, lymphocytes: 1.25–3.49 G/l, monocytes: 0.06–0.31 G/l, eosinophils: 0.04–0.50 G/l, glucose: 4.0–5.7 mmol/l, urea: 3.2–6.4 mmol/l, creatinine: 79.6–141.4 μmol/l, total protein: 54.4–72.9 g/l, albumin: 27.7–36.8 g/l, total bilirubin: 8.1–21.1 μmol/l, triglycerides: 0.03–0.44 mmol/l, cholesterol: 1.75–2.90 mmol/l, ALP: 1.35–3.55 μkat/l, AST: 4.52–8.80 μkat/l, GLDH: 0.0–0.18 μkat/l, GGT: 0.11–0.39 μkat/l, CK: 2.53–6.52 μkat/l, LDH: 3.32–7.95 μkat/l, iron: 16.4–39.9 μmol/l, calcium: 2.69–3.19 mmol/l, phosphate: 0.5–1.3 mmol/l, magnesium: 0.6–0.9 mmol/l, sodium: 134–141 mmol/l, potassium: 3.6–4.7 mmol/l, chloride: 100–105 mmol/l.

Conclusions

Reference intervals of several haematologic and biochemical analytes differed from the transferred historical reference intervals applied to equine samples in the authors’ laboratory. These might be of clinical importance in some analytes such as creatine kinase.

Electronic supplementary material

The online version of this article (doi:10.1186/s13028-015-0120-4) contains supplementary material, which is available to authorized users.     

Tonographic effects of pilocarpine and pilocarpineepinephrine in dogs

Topical pilocarpine (1·0, 2·0 and 4·0 per cent) and 2·0 per cent pilocarpine plus 1·0 per cent epinephrine markedly increased conventional aqueous humour outflow, as measured by noninvasive tonography, in both normal beagles and beagles with inherited glaucoma. Pilocarpine in normal eyes increased the coefficient of outflow from 0·33 μl/min/mmHg (pre-drug) to 0·55 μl/min/mmHg (1·0 per cent), 0·57 μl/min/mmHg (2·0 per cent), and 0·61 μl/min/mmHg (4·0 per cent). In beagles with inherited glaucoma, topical pilocarpine increased the coefficient of outflow from 0·15 μl/min/mmHg (pre-drug) to 0·24 μl/min/mmHg (1·0 per cent), 0·21 μl/min/mrnHg (2·0 per cent) and 0·38 μl/min/mmHg (4·0 per cent). The 2·0 per cent pilocarpine plus 1·0 per cent epinephrine solution in normal eyes increased the coefficient of outflow from 0·27 μl/min/mmHg to 0·36 μl/min/mmHg. In the glaucomatous eyes the 2 per cent pilocarpine plus 1 per cent epinephrine combination increased the coefficient outflow from 0·20 μl/min/mmHg to 0·30 μl/min/mmHg.     

Production of plantlets from tissue cultures of Lotononis,a southern African veld legume1

Abstract

A simple procedure is described for the production of large numbers of rooted plantlets from callus cultures of Lotononis bainesii Baker. Highest frequency of shoots was obtained from somatic embryos formed in initiation cultures on Murashige & Skoog medium plus 1 mg/l benzylaminopurine plus 1 mg/l naphthaleneacetic acid. The somatic embryos from these initiation cultures were transferred to media containing 0,5,10 or 20 mg/l isopentenyladenine or 0,1 or 5,0 mg/l kinetin (1,8 to 3,1 shoots per culture) where they re‐callused and produced shoots. All shoots obtained from the cultures on media containing 0,5, 10 or 20 mg/l isopentenyladenine or 0,1 mg/l kinetin were rooted; 35 % of shoots from the cultures on medium containing 5,0 mg/l kinetin were rooted. Rooting of unrooted shoots from other treatments was readily induced on medium containing 0,1 mg/l indoleaceticacid.     

Chemical form of dietary l‐Carnitine affects plasma but not tissue Carnitine concentrations in male Sprague–Dawley rats

In Experiment 1, rats (n = 54) were randomly assigned to control or one of the four sources of l ‐Carnitine supplemented at either 100 or 200 μmol/kg/day and were allowed to acclimate for 14 days. Following a 12‐h fast, plasma samples were obtained at 0, 5, 10, 15, 30, 60, 120, 240, 480 and 720 min after l ‐Carnitine feeding and assayed for free l ‐Carnitine concentration. Plasma‐free l ‐Carnitine levels were affected by time after treatment intake (p < 0.0001) and l ‐Carnitine source (p < 0.0001). The time × source interaction was not statistically significant (p = 0.99). In Experiment 2, rats (n = 54) were randomly assigned to control or one of the four sources of l ‐Carnitine at either 100 or 200 μmol/kg/day and were acclimated as in experiment 1. Rats were sacrificed 120 min after feeding. Samples of liver and skeletal muscle were obtained and assayed for free l ‐Carnitine concentration. Neither skeletal muscle (p = 0.44) or liver (p = 0.59) tissue concentrations of l ‐Carnitine were affected by any l ‐Carnitine source as compared with the control. We conclude that some differences exist in plasma concentrations of free l ‐Carnitine following ingestion of different chemical forms of l ‐Carnitine. It is unclear if these differences in the circulating concentration of free l ‐Carnitine translate into any physiological differences for the animal. In this study, chemical form of l ‐Carnitine had no effect on skeletal muscle or liver tissue concentrations of l ‐Carnitine in young male Wistar rats.     

Effect of dosage and application mode of l‐carnitine on plasma lipid and egg‐yolk cholesterol of turkeys,hatchability of eggs and post‐hatch growth of their offsprings

The effect of dosage and application mode of l ‐carnitine on plasma lipid and egg‐yolk cholesterol of breeder turkeys, hatchability of eggs and post‐hatch growth response was investigated using 180 breeder hens. The hens were assigned to six dietary treatments in a 2 × 3 factorial arrangements of two application modes of l ‐carnitine (diet and drinking water) supplemented at 0, 50 and 100 ppm (mg/kg or mg/l) levels, respectively. Each treatment was replicated five times with six hens per replicate. Dietary inclusion of 50 ppm l ‐carnitine showed the lowest (p < 0.01) plasma total cholesterol (TC) and low‐density lipoprotein concentration (LDL). Breeder hens offered 50 ppm l ‐carnitine with no regard to application mode recorded the highest (p < 0.01) plasma high‐density lipoprotein (HDL). Hens offered 50 and 100 ppm l ‐carnitine irrespective of application mode also showed reduced (p < 0.01) egg‐yolk TC concentration at 32 weeks of age. Dietary supplementation of 50 ppm l ‐carnitine for breeder turkeys recorded the lowest (p < 0.01) egg‐yolk triglyceride (TG) at 40 weeks of age. Hens offered 50 ppm l ‐carnitine irrespective of application mode recorded the highest (p < 0.05) hen‐day egg production. Incidence of dead‐in‐shell also reduced (p < 0.05) with increasing dosage of l ‐carnitine. Dietary supplementation of 50 ppm and oral application in drinking water of 100 ppm l ‐carnitine for breeder turkeys resulted in highest (p < 0.05) egg fertility. Offsprings from breeder hens fed diets supplemented with l ‐carnitine recorded no post‐hatch mortality. Highest (p < 0.05) post‐hatch final live weight and weight gain was obtained with poults obtained from hens fed diet supplemented with 50 ppm l ‐carnitine. In conclusion, dietary supplementation of 50 ppm l ‐carnitine for turkey hens showed improved serum lipid profile, egg fertility, reduced dead‐in‐shell, egg‐yolk cholesterol and resulted in improved post‐hatch growth performance.     

UBE2L3对牛骨骼肌卫星细胞增殖分化的影响

将分离的牛骨骼肌卫星细胞(BSMSCs)进行体外培养,首先检测泛素结合酶UBE2L3在BSMSCs增殖分化过程中mRNA以及蛋白表达水平的变化.设计UBE2L3的3个干扰RNA(si-UBE2 L3-1、si-UBE2L3-2、si-UBE2L3-3),对干扰效果进行筛选.构建UBE2L3过表达质粒载体pcDNA3.1...     

Estimation of genetic and crossbreeding parameters for daily milk yield of Ayrshire × Sahiwal × Ankole crossbred cows in Burundi

The pedigree of 317 cows of which 184 were controlled for milk production has been used to estimate crossbreeding parameters for daily milk yield of Ayrshire, Sahiwal and Ankole crosses in the Mahwa station. Lactating cows belonged to one of 6 different genetic groups defined on the basis of the mating system used to produce them. REML estimates of the genetic parameters were obtained with a repeated animal model using daily milk records. Estimated heritability (h²) and repeatability (r²) were 0.27 and 0.36, respectively. The genetic group effects were used to estimate crossbreeding parameters following Dickerson's genetic model. Estimates for the additive effects for daily milk yield of Ankole, Sahiwal and Ayrshire breeds were − 1.66l, − 0.48l and 5.22l, respectively. Estimates of direct heterosis for daily milk yield for Sahiwal × Ankole, Ayrshire × Ankole, and Ayrshire × Sahiwal crosses were 1.97l, 2.30l and − 2.33l, respectively.     

Effects of medetomidine,l‐methadone,and their combination on arterial blood gases in dogs

ObjectiveTo investigate the influence of l–methadone on medetomidine–induced changes in arterial blood gases and clinical sedation in dogs.Study designProspective experimental cross–over study (Latin square design).AnimalsFive 1–year–old purpose bred laboratory beagle dogs of both sexes.MethodsEach dog was treated three times: medetomidine (20 μg kg^?1 IV), l–methadone (0.1 mg kg^?1 IV) and their combination. Arterial blood was collected for blood gas analysis. Heart and respiratory rates were recorded, and clinical sedation and reaction to a painful stimulus were scored before drug administration and at various time points for 30 minutes thereafter.ResultsArterial partial pressure of oxygen decreased slightly after medetomidine administration and further after medetomidine/l–methadone administration (range 55.2–86.7 mmHg, 7.4–11.6 kPa, at 5 minutes). A slight increase was detected in arterial partial pressure of carbon dioxide after administration of l–methadone and medetomidine/l–methadone (42.6 ± 2.9 and 44.7 ± 2.4 mmHg, 5.7 ± 0.4 and 6.0 ± 0.3 kPa, 30 minutes after drug administration, respectively). Arterial pH decreased slightly after administration of l–methadone and medetomidine/l–methadone. Heart and respiratory rates decreased after administration of medetomidine and medetomidine/l–methadone, and no differences were detected between the two treatments. Most dogs panted after administration of l–methadone and there was slight sedation. Medetomidine induced moderate or deep sedation, and all dogs were deeply sedated after administration of medetomidine/l–methadone. Reaction to a noxious stimulus was strong or moderate after administration of methadone, moderate or absent after administration of medetomidine, and absent after administration of medetomidine/l–methadone.Conclusions and clinical relevanceAt the doses used in this study, l–methadone potentiated the sedative and analgesic effects and the decrease in arterial oxygenation induced by medetomidine in dogs, which limits the clinical use of this combination.