京海黄鸡GH基因与生长、屠体性状的关联分析

试验将生长激素(GH)基因作为影响鸡生长、屠体性状的候选基因,以京海黄鸡为材料,采用PCR-SSCP技术对京海黄鸡的GH基因的5个外显子进行SNPs检测和基因型分析,探讨GH基因的多态性与鸡生长、屠体性状之间的关系.在GH基因外显子4上发现突变位点,表现为3种基因型,分别为AA、AB和BB基因型.统计结果显示,公鸡的活重、脾重、肝重、头重、脚重、腺胃重、肌胃重、腿肌重和半净膛重在不同基因型间呈现差异显著(P<0.05),AA基因型最高.母鸡的脾重、肝重、脚重在不同基因型间差异显著,其余性状在各基因型间差异均不显著(P>0.05).这表明该基因可能调控鸡生长、屠体性状的主效基因或与控制生长、屠体性状的主基因连锁,可以将该突变位点作为京海黄鸡进行生长、屠体性状筛选的候选分子辅助标记.     

京海黄鸡IGF-Ⅰ基因与生长和屠体性状的关联分析

实验将类胰岛素生长因子Ⅰ(IGF-Ⅰ)作为研究鸡生长、屠体性状的候选基因,以京海黄鸡为材料,采用PCR-SSCP技术对京海黄鸡的IGF-Ⅰ基因5′非编码区和第1外显子进行SNPs检测和基因型分析,探讨IGF-Ⅰ基因的多态性与鸡生长、屠体性状之间的关系。在IGF-Ⅰ基因5′端非编码区上发现1个突变,统计结果显示:活重、腿肌重、半净膛重和全净膛重在不同基因型之间均存在显著差异(P<0.05),AA基因型显著高于BB基因型个体。结果表明:该基因可能调控鸡生长、屠体性状或与控制生长、屠体性状的主基因连锁。由此推测,可以将IGF-Ⅰ基因作为鸡生长、屠体性状的辅助标记。     

京海黄鸡IGF-I基因与生长和屠体性状的关联分析

实验将类胰岛素生长因子I(IGF-I)作为研究鸡生长、屠体性状的候选基因,以京海黄鸡为材料,采用PCR-SSCP技术对京海黄鸡的,IGF-I基因5'非编码区和第1外显子进行SNPs检测和基因型分析,探讨IGF-I基因的多态性与鸡生长、屠体性状之间的关系.在IGF-I基因5'端非编码区上发现1个突变,统计结果显示:活重、腿肌重、半净膛重和全净膛重在不同基因型之间均存在显著差异(P<0.05),AA基因型显著高于BB基因型个体.结果表明:该基因可能调控鸡生长、屠体性状或与控制生长、屠体性状的主基因连锁.由此推测,可以将IGF-I基因作为鸡生长、屠体性状的辅助标记.     

优质鸡MEF2A基因的SNPs检测及其与屠体性状的相关研究

为了解优质鸡MEF2A基因SNPs与屠体性状的相关性,以240只大恒优质肉鸡为材料,应用12对引物,采用PCR-SSCP技术对肌细胞特异性增强子因子2A(MEF2A)基因进行多态性检测.结果在该研究群体中检测到MEF2A基因的3个SNPs位点46 023 nt(C→T,SNP1)、72 626 nt(G→A,SNP2)和89 232 nt(G→T,sNP3).关联分析结果表明,MEF2A基因3个SNPs位点及其双倍型对部分屠体性状有显著(P<0.05)或极显著(P<0.01)影响.最小二乘分析结果表明,SNP1中,基因型A2A2个体的活体质量、屠体质量、胸肌质量和腹脂质量最小二乘均值显著(P<0.05)或极显著(P<0.01)大于A1A1个体;SNP2中,基因型B1B1个体的活体质量、屠体质量、胸肌质量、腿肌质量和腹脂质量的最小二乘均值显著(P<0.05)或极显著(P<0.01)大于B282个体;SNP3中的基因型C1C1个体的半净膛率显著高于基因型C2C2个体(P<0.05).双倍型H1H2组合的活体质量、屠体质量、胸肌质量和腿肌质量的最小二乘均值均高于其他双倍型组合.H5H5双倍型的活体质量、屠体质量和胸肌质量的最小二乘均值均为最低.初步推断MEF2A基因可以作为影响鸡屠体性状的分子标记.     

鸡MC3R基因多态性及其与屠体和肉质性状的相关性

以四川大恒家禽育种有限公司和四川省畜牧科学研究院培育的5个新品系纯系和3个杂交系鸡群为试验材料,对MC3R基因进行PCR扩增,采用PCR-SSCP技术结合测序分析了MC3R基因在上述鸡群中的多态性.结果表明8个鸡群中存在A 1 424 G的突变.经过基因型与屠体性状的关联分析得知各基因型除与半净膛率(SEP)和腿肌率(LMP)无显著影响(P＞0.05)外,对其它屠体性状则有显著(P＜0.05)和极显著影响(P＜0.01);与肉质性状相关分析结果显示,1 424位点仅对粗蛋白(CP)含量和肌内脂肪含量(IMF)影响显著(P＜0.05).     

京海黄鸡MC4R基因多态性及其与部分屠体性状的关联分析

以140只京海黄鸡个体为研究对象,采用PCR-SSCP和克隆测序技术分析了鸡MC4R基因的多态性。结果表明:MC4R基因第662位发生G→C突变,第733~734位间插入1个C碱基;χ2检验结果表明,实验中发现的多态位点均处于Hardy-Weinberg不平衡状态;GLM分析结果显示,AB型个体腿肌重极显著高于BB型(P0.01),DD型个体胴体重和半净膛重显著高于CD型(P0.05),AA/DD组合型个体具有高于其他基因型的趋势。因此推测,MC4R基因可以作为影响和控制鸡屠体性状的候选基因。     

京海黄鸡甲状腺激素应答蛋白Spot14α基因外显子1多态性与屠体和腹脂性状的相关性分析

本研究旨在寻找甲状腺激素应答蛋白Spot14α(thyroid hormone responsive Spot14α,THRSPα)基因的多态位点,并分析其对京海黄鸡屠体和腹脂性状产生的影响。针对THRSPα基因外显子区,利用PCR-SSCP结合测序技术对379只140日龄京海黄鸡进行SNP检测,结果发现,该基因第1外显子区存在9 bp插入缺失多态位点,形成3种基因型：AA、AB和BB,2种等位基因：A、B,基因频率分别为0.4485、0.5515。相关分析结果表明,该位点对京海黄鸡140日龄活重、屠体性状（包括屠体重、头重、脚重、翅重、胸肌重、腿肌重、全净膛重、半净膛重）和腹脂性状均没有显著影响(P>0.05)。因此推断该多态位点在京海黄鸡分子辅助标记育种中不能作为屠体和腹脂性状筛选的候选分子辅助标记。     

京海黄鸡IGF-1R基因AluⅠ和Hin1Ⅰ位点与屠宰性状的关联分析

研究采用PCR-RFLP法检测类胰岛素生长因子Ⅰ型受体(IGF-1R)基因AluⅠ和Hin1Ⅰ位点的遗传多态性,并分析多态位点与京海黄鸡屠宰性状的相关性。结果表明:对于AluⅠ位点共检测到AA、AB和BB三种基因型。关联分析表明该位点仅对腿肌率有显著的影响(P0.05),而对其余屠宰性状的影响均不显著(P0.05)。对于Hin1Ⅰ位点检测到CC、CD和DD三种基因型。关联分析表明该突变位点对所测定的屠宰性状的影响均不显著(P0.05)。研究结果提示,AluⅠ和Hin1Ⅰ位点对京海黄鸡屠宰性状的影响较小,不适合作为京海黄鸡140日龄屠体性状的遗传标记。     

鸡CACNA1S基因SNPs及其与部分屠体性状的关联性研究

为了研究L型钙离子通道α1亚单位(CACNA1S)编码基因与动物肌肉收缩和发育的关系,试验采用PCR-SSCP技术,首次对萧山鸡、仙居鸡、灵昆鸡、萧山鸡×仙居鸡杂交F1代、爱拔益加鸡(AA鸡)CACNA1S基因5’-调控区(5’-UTR)和外显子1进行多态性检测,同时结合屠体性状进行关联分析。结果表明:试验群体CACNA1S基因5’-UTR和外显子1存在2个单核苷酸多态性(SNPs)位点与屠体性状关联;SNPs716位点JJ基因型的胸肌率极显著大于KK基因型(P<0.01),SNPs1711位点YY基因型的胸肌率极显著大于XY和XX基因型(P<0.01),YY基因型的半净膛率极显著大于XX基因型(P<0.01)。初步推断CACNA1S基因可能是影响鸡部分屠体性状(全净膛率、半净膛率、胸肌率、腿肌率)的主效基因或与主效基因连锁,并且这些突变位点可能作为分子遗传标记用来选择鸡的屠体性状。     

鸡PRR5L基因5′UTR多态性及其与脂肪性状、屠体性状的关联分析

试验旨在研究类富脯氨酸5(proline rich 5like,PRR5L)基因遗传变异对鸡脂肪性状及屠体性状的影响。以矮脚黄鸡为研究对象,根据GenBank公布的鸡PRR5L基因全序列(登录号:XM_015287209.1)设计扩增引物,利用PCR直接测序技术检测PRR5L基因的5′UTR区域单核苷酸多态性(SNPs),并用统计学方法分析其与鸡脂肪性状及屠体性状的关联性。结果发现,PRR5L基因5′UTR区域存在C480G、G514A和A579G3个多态位点,均表现出3种基因型。χ2适合性检验结果发现,群体在G514A位点处于Hardy-Weinberg非平衡状态(P0.05);在C480G和A579G位点均处于Hardy-Weinberg平衡状态(P0.05)。基因型与性状关联分析结果显示,在脂肪性状方面,PRR5L基因3个多态位点各基因型间腹脂重、腹脂率和肌内脂肪含量差异均不显著(P0.05);在屠体性状方面,在G514A位点处AG与GG基因型的胸肌重差异显著(P0.05),其余指标差异均不显著(P0.05)。因此,可推断PRR5L基因5′UTR的G514A位点可能是一个影响鸡胸肌生长发育的位点,但该位点能否作为标识鸡屠体性状的分子标记辅助选择还需要进一步探究。     

Phase I evaluation of CCNU (lomustine) in tumor-bearing cats

1-(2-Chloroethyl)3-cyclohexyl-1-nitrosourea (CCNU) is an alkylating agent in the nitrosourea subclass. A prospective evaluation of CCNU was done to determine the maximally tolerated dosage of CCNU in tumor-bearing cats. Response data were obtained when available. Twenty-five cats were treated with CCNU at a dosage of 50-60 mg/m3 body surface area. Complete hematologic data were available for 13 cats. Neutropenia was the acute dose-limiting toxicity. The median neutrophil count at the nadir was 1,000 cells/microL (mean, 2,433 cells/microL; range, 0-9,694 cells/microL). The time of neutrophil nadir was variable, occurring 7-28 days after treatment, and counts sometimes did not return to normal for up to 14 days after the nadir. Based on these findings, a 6-week dosing interval and weekly hematologic monitoring after the 1st treatment with CCNU are recommended. The nadir of the platelet count may occur 14-21 days after treatment. The median platelet count at the nadir was 43,500 cells/microL. No gastrointestinal, renal, or hepatic toxicities were observed after a single CCNU treatment, and additional studies to evaluate the potential for cumulative toxicity should be performed. Five cats with lymphoma and 1 cat with mast cell tumor had measurable responses to CCNU. Phase II studies to evaluate antitumor activity should be completed with a dosing regimen of 50-60 mg/m3 every 6 weeks.     

Furosemide continuous rate infusion in the horse: evaluation of enhanced efficacy and reduced side effects

Continuous rate infusion (CRI) of furosemide in humans is considered superior to intermittent administration (IA). This study examined whether furosemide CRI, compared with IA, would increase diuretic efficacy with decreased fluid and electrolyte fluctuations and activation of the renin-angiotensin-aldosterone system (RAAS) in the horse. Five mares were used in a crossover-design study. During a 24-hour period, each horse received a total of 3 mg/kg furosemide by either CRI (0.12 mg/kg/h preceded by a loading dose of 0.12 mg/kg IV) or IA (1 mg/kg IV q8h). There was not a statistically significant difference in urine volume over 24 hours between methods; however, urine volume was significantly greater after CRI compared with IA during the first 8 hours ([median 25th percentile, 75th percentile]: 9.6 L [8.9, 14.4] for CRI versus 5.9 L [5.3, 6.0] for IA). CRI produced a more uniform urine flow, decreased fluctuations in plasma volume, and suppressed renal concentrating ability throughout the infusion period. Potassium, Ca, and Cl excretion was greater during CRI than IA (1,133 mmol [1.110, 1,229] versus 764 mmol [709, 904], 102.7 mmol [96.0, 117.2] versus 73.3 mmol [65.0, 73.5], and 1,776 mmol [1,657, 2.378] versus 1,596 mmol [1,457, 1,767], respectively). Elimination half-lives of furosemide were 1.35 and 0.47 hours for CRI and IA, respectively. The area under the excretion rate curve was 1,285.7 and 184.2 mL x mg/mL for CRI and IA, respectively. Furosemide CRI (0.12 mg/kg/h) for 8 hours, preceded by a loading dose (0.12 mg/kg), is recommended when profound diuresis is needed acutely in horses.     

The Epidemiology of Gastrointestinal Nematodes of Dairy Cattle in Central Kenya

The epidemiology of H. placei and of other gastrointestinal nematodes in yearling dairy cattle was examined on two farms in Kiambu District, central Kenya during each of 13 one-month periods from April 1993 to April 1994. On each farm, 32 newly weaned dairy calves were given a single dose of albendazole and then placed on experimental pastures. Twelve of the animals were designated for bi-monthly slaughter (n = 2) and analysis of worm population characteristics and 20 were designated for blood and faecal collection and for weighing. Two parasite-free tracer calves were grazed alongside the weaner calves each month throughout the study period and were also slaughtered for analysis of worm populations. Faecal egg counts, haematological and serum pepsinogen determinations, herbage larval counts, and animal live weight changes were recorded monthly. The study revealed that Haemonchus placei, Trichostrongylus axei, Cooperia spp. and Oesophagostomum radiatum were responsible for parasitic gastroenteritis and that H. placei was the predominant nematode present in the young cattle on both farms. Faecal egg counts from resident cattle and necropsy worm counts revealed that pasture larval levels were directly related to the amount of rainfall. The total worm burdens in the animals were highest during the rainy season (March–June and October–December) and lowest during the dry seasons (July–September and January–February). The very low recovery of immature larvae of H. placei from the tracer calves indicated that arrested development is not a feature of the life cycle of this parasite in central Kenya. The maintenance of the parasite population depended on continuous cycling of infection between the host and the pasture. The agroclimatic conditions of the study area were such that, in general, favourable weather conditions for the development and survival of the free-living stages of gastrointestinal nematodes existed all year round.     

Diversity of Ectoparasites in Sheep Flocks in Sa~o Paulo,Brazil

The occurrence of ectoparasites in sheep flocks is frequently reported but seldom quantified. Sheep production used to be a predominantly family activity in the state of Sa~o Paulo (Brazil), but it began to become a commercial activity in the past decade. Thus, information about the ectoparasites existing in sheep flocks has become necessary. The present data were obtained by means of questionnaires sent to all sheep breeders belonging to the `Associaça~o Paulista de Criadores de Ovinos' (ASPACO; Sa~o Paulo State Association of Sheep Breeders). Response reliability was tested by means of random visits paid to 10.6% of the respondents. Most of the properties (89.5%) reported the presence of one or more ectoparasites. Screw-worm (Cochliomyia hominivorax) was the most frequent ectoparasite (72.5%), followed by bot fly larvae (Dermatobia hominis, 45.0%), ticks (Amblyomma cajennense) and Boophilus microplus, 31.3%) and finally lice (Damalinia ovis, 13.8%). Combined infestations also occurred, the most common one being screw-worm with bot fly larvae (36.0%) followed by bot fly larvae with ticks (13.9%), screw-worm with ticks (9.3%), bot fly larvae with lice (6.9%), and ticks with lice (5.0%). The most common triple combination was screw-worm, bot fly larvae and ticks (12.8%). Breeds raised for meat or wool were attacked by bot fly larvae and ticks more often than other breeds. Lice were only absent from animals of indigenous breeds. The relationships among these ectoparasites are discussed in terms of sheep breeds, flock size, seasonality and the ectoparasitic combinations on the host.     

Evaluation of biohydrogenation rate of canola vs. soya bean seeds as unsaturated fatty acids sources for ruminants in situ

An experiment was conducted to study disappearance of C14 to C18 fatty acids, lag times and biohydrogenation (BH) rates of C18 fatty acids of ground soya bean and canola seeds in situ. Three ruminally fistulated Dallagh sheep were used to determine ruminal BH of unsaturated fatty acids (UFAs). Differences in the disappearance of fatty acids through the bags and lag times were observed between the oilseeds. We saw that the longer the incubation time of the oilseeds in the rumen, the lower the content of C18:2 and C18:3. Significantly higher lag times for both C18:2 and C18:3 were observed in ground canola compared to ground soya bean. BH rates of C18:2 and C18:3 fatty acids in soya bean were three times higher than those of canola. These results suggest that the fatty acid profile of fat source can affect the BH of UFAs by rumen micro‐organisms. So that UFAs of canola had higher ability to escape from ruminal BH. It seems that fatty acid profile of ruminant products is more affected by canola seed compared to soya bean seed.     

Serum biochemical values and mineral element contents of tissues in yaks

Serum biochemical values and the wet weight to dry weight ratios of tissues were determined in yaks in Shandan county of Gansu province. The liver, kidney, heart and muscle contents of seven elements in yaks were also analysed. Most serum biochemical values were similar to those of cattle, camels and sheep, but the calcium concentration was considerably above the normal range for other ruminants. The liver contained the highest concentrations of copper, manganese and cobalt and the kidney of selenium, iron and calcium.Abbreviations Alb albumin - ALT alanine aminotransferase - AST aspartate aminotransferase - BUN blood urea nitrogen - Chol cholesterol - Glob globulin - -GT -glutamyl transpeptidase - IP inorganic phosphorus - TP total protein     

Evaluation of the Microbiological Status of Milk and Various Structures in Mammary Glands from Naturally Infected Dairy Cows

A knowledge of the microbiological status of milk and of the different structures in the mammary glands has great importance in elucidating the pathogenesis of mammary gland infections. The objective of this study was to evaluate the microbiological status of various structures in the mammary glands from naturally infected dairy cows following slaughter. A total of 94 samples of milk, 184 samples of mammary parenchyma, 168 samples of gland cisterns, and 168 samples of teat cisterns were collected for microbiological examination. Microorganisms were detected in 59.9% of all samples, 67.0% of the milk samples, 70.1% of the mammary parenchymas, 55.9% of the gland cisterns and 48.8% of the teat cistern samples. When all samples were considered, coagulase-negative Staphylococcus were the most prevalent (35.7%) followed by coagulase-positive Staphylococcus (12.2%), Corynebacterium bovis (2.4%), Prototheca sp. (1.9%), and Streptococcus dysgalactiae (1.5%). There was a significantly higher occurrence of microorganisms in the milk and mammary parenchyma compared to the gland cisterns and teat cisterns. This revised version was published online in July 2006 with corrections to the Cover Date.     

Development and survival of free-living stages of gastrointestinal nematodes of sheep and goats on pasture in the Nigerian derived savanna

Four grass plots were sequentially contaminated with goat faeces containing known numbers of unembryonated eggs of predominantly Haemonchus contortus and Trichostrongylus spp. between October 1982 and April 1983. Four other plots were similarly contaminated with sheep faeces between February and May 1987. An additional plot was repeatedly contaminated with sheep faeces from February to April 1987. Populations of free-living stages in faeces and of infective larvae (L₃) in the herbage were subsequently monitored until the end of April and June of 1983 and 1987 respectively. During February and May 1987 two control cultures of sheep faeces were incubated in the laboratory at 25°C–30°C and at a constant temperature of 50°C and the free-living development was also monitored. L₃ developed very readily in the faeces cultured at 25°C–30°C and in those spread on a grass plot in October, at the end of the wet season, but developed less on the plot contaminated in May at the start of the wet season. Worm eggs in faeces deposited on plots during the hot dry season (December to April) or incubated at 50°C died and disintegrated after 24–48 h exposure to the high environmental temperatures. The results indicate that it is unlikely that gastrointestinal nematodes of sheep and goats can develop or survive on open pasture during the dry season in the Nigerian derived savanna zone.