务川黑牛杂交改良效果初步研究

该研究对农户饲养的务川黑牛及其与西门塔尔牛、利木赞牛、安格斯牛的杂交F1牛的初生、6月龄、12月龄、18月龄及24月龄的体尺、体重进行了测定。结果表明:1务川黑牛经杂交改良后,其后代西×务F1、安×务F1、利×务F1牛各年龄段主要体尺都有极显著提高(P0.01),杂交F1牛的初生重和各月龄体重也均有极显著提高(P0.01);2杂交F1牛初生至24月龄平均日增重,西×务F1、安×务F1、利×务F1公(母)牛分别为369.0 g(359 g)、405 g(377 g)、382 g(362 g),比务川黑牛公(母)牛的216 g(202 g)分别提高了70.83%(77.25%)、87.50%(86.63%)、76.85%(79.21%);杂交F1公(母)牛的初生至24月龄平均生长系数分别比务川黑牛公(母)提高了12.10%和7.15%;33种杂交组合F1公(母)牛体尺间差异均不明显(P0.05),增长速度以安×务F1牛提高幅度最大(P0.01)。表明用西门塔尔牛、利木赞牛、安格斯牛杂交改良务川黑牛可以取得良好的改良效果,其中以用安格斯牛杂交改良效果最好。     

德国弗莱维赫(Fleckvieh)牛和本地牛杂交F1代母牛生长发育性状测定及分析

[目的]为了研究德国弗莱维赫(Fleckvieh)牛与本地母牛杂交F_1代育成母牛生长发育性状和生长发育规律,为培育北大荒乳肉兼用牛品种,开展选育提高奠定基础。[方法]采用各批次测定体重校正到统一月龄,测定了其初生、4月龄(断奶)、12月龄及18月龄4个阶段的体重、体尺,并对各阶段表型值比较分析。[结果]德国弗莱维赫(Fleckvieh)牛与本地母牛杂交F_1代母牛平均日增重、胸围和体斜长性状,在初生至4月龄断奶阶段生长发育最快;从4月龄断奶至18月龄,与纯种德国弗莱维赫种公牛与澳系(澳大利亚)西门塔尔母牛杂交后代相比,在体重和体尺上有一定差异。[结论]需要不断地改良,以提高后代的生长发育性状,进一步提高生产性能。     

安格斯牛×大别山牛杂交牛生长发育特性和屠宰特性研究

[目的]研究安格斯牛对大别山牛的杂交效果。[方法]对安格斯牛×大别山牛杂交F1代(安—大F1)和大别山牛各24头进行了初生、6月龄、12月龄和24月龄体重和体尺性状测定,对照组和试验组各随机选择3头持续育肥至24月龄后进行了屠宰测定。[结果]安—大杂交F1代牛具有较高的杂种优势,安—大杂交F1代牛初生、6月龄、12月龄、18月龄和24月龄体重和体尺指标均明显优于大别山牛;24月龄时安—大杂交F1代的宰前体重极显著高于大别山牛(P<0.01),胴体重和净肉重均显著高于大别山牛(P<0.05)。[结论]用安格斯牛与大别山牛杂交,杂交效果明显,具有较高的推广及应用价值。     

贵州威宁黄牛杂交改良效果初步研究

本研究对农户饲养条件下的984头威宁黄牛及西×威F1、安×威F1、利×威F1初生、6月龄、12月龄、18月龄、24月龄的体尺、体重进行了测定。结果表明:(1)西×威F1、安×威F1、利×威F1代牛的体斜长、胸围、体高、管围和十字部高分别平均增加16.69%~22.25%,20.20%~25.93%,16.38%~20.46%,18.03%~28.46%,15.96%~19.80%(P<0.01);(2)杂交F1代♂牛24月龄体重平均提高76.46%(P<0.01),日增重平均提高78.76%,生长系数平均提高12.13%;杂交F1代♀体重提高80.54%(P<0.01)、日增重平均提高67.16%,生长系数平均提高7.18%;(3)三种杂交F1代牛之间体尺差异不明显(P>0.05),增长速度以安×威F1提高幅度最大(P<0.05)。从而认为,用安格斯牛、西门塔尔牛、利木赞牛改良威宁黄牛可以取得良好的杂交效果,其中以用安格斯牛改良的效果更为明显。     

云南黄牛杂交改良效果分析

[目的]为了提高云南黄牛的生产性能,优选主要的杂交改良父本,开展云南黄牛杂交改良。[方法]用西门塔尔牛、短角牛、安格斯牛、海福特牛等分别与云南黄牛母本杂交,测定不同杂交组合后代初生、6月龄、12月龄、24月龄的体重体尺。[结果]云南黄牛经过杂交改良后,改良效果良好,杂交后代对云南高原的气候条件适应性良好。在农村饲养条件下,西×云杂一代牛初生重平均为24.57kg,6月龄体重平均为135.83kg,12月龄体重平均为196.21kg,24月龄体重平均为344.24kg,分别比本地黄牛提高74.13%,59.20%,56.53%和78.10%。短×云杂交一代牛初生重平均为22.28kg,6月龄体重平均为117.20kg,12月龄体重平均为193.56kg,24月龄体重平均为314.86kg,分别比本地黄牛提高57.90%,38.10%,54.21%和62.90%;安×云杂交一代牛犊牛初生重平均为21.21kg,6月龄体重平均为134.34kg,12月龄体重平均为196.18kg,24月龄体重平均为268.45kg,分别比本地黄牛提高50.32%,57.45%,56.51%和38.89%;海×云杂交一代牛初生重平均为22.78kg,6月龄体重平均为124.97kg,12月龄体重平均为190.52kg,24月龄体重平均为289.50kg,分别比本地黄牛提高61.45%,46.47%,51.99%和49.78%。[结论]西×云杂一代牛、短×云杂交一代牛、安×云杂交一代牛和海×云杂交一代牛生产性能显著提高,效益明显。     

海福特牛改良枣北黄牛的效果分析

为了提高枣北黄牛的生产性能,利用海福特牛冻精改良枣北黄牛,对海福特牛×枣北黄牛(海×枣)F_1代黄牛及枣北黄牛体型外貌、生长发育性状及屠宰性能进行了观测比较。结果表明,海×枣F_1代杂交牛具有较明显的杂种优势,海×枣F_1代牛初生、6月龄、12月龄、18月龄体重和体尺均明显优于枣北黄牛;24月龄时,海×枣F_1代的宰前重、胴体重、净肉重均极显著高于枣北黄牛(P0.01),屠宰率和净肉率明显高于枣北黄牛。说明海福特牛杂交改良枣北黄牛效果显著,适合在天门地区推广。     

豫北黄牛及其杂交改良牛的生长发育研究

通过测定分析了西利本杂交牛、利本F1杂交牛和豫北黄牛的初生－24月龄体尺、体重指标，结果表明，西利本三元杂交牛生产发育快，各月龄体尺、体重显著大于豫北黄,比利本F1也有显著提高。     

云南省肉牛杂交改良效果调查

通过对农户饲养条件下不同引入品种 (短角牛、西门塔尔牛、安格斯牛 )与云南滇东北本地黄牛的杂交F1代及本地牛的初生 ,6 ,12 ,18,2 4月龄体重、体尺测定以及经济效益调查分析表明 :(1)滇东北本地黄牛经杂交改良后 ,胸围、十字部高等主要体尺都有极显著提高 ;初生重和各月龄体重均有显著提高 ;(2 )调查 12 1头市场交易牛发现 ,养一头杂交牛的经济收入比养本地牛高 4 9%～ 2 31%。 (3)从建立长期的肉牛杂交改良体系角度考虑 ,在云南省东北部地区 ,首先应使用短角牛、安格斯牛等中小型肉牛与本地黄牛进行杂交 ,然后再用西门塔尔牛杂交。     

湘西黄牛各世代与安格斯牛杂交效果调查研究

通过对522头湘西黄牛0~Ⅲ世代与安格斯牛杂交后代的体重、体尺指标测定,结果表明:各世代杂交牛在各年龄段的体重、体尺指标均较杂交零世代有了明显提高,以Ⅲ世代杂交牛效果尤为明显,其初生、6月龄、12月龄、18月龄和24月龄体重较杂交零世代提高了113.66%、37.76%、42.35%、34.28%和48.34%,体尺数据也有明显提高。     

西门塔尔改良遵义市黄牛的效果分析

对遵义市西门塔尔牛改良的本地黄牛（西杂牛）体尺、体重及各项生产性能进行了测定,结果西本杂交牛与本地牛体尺体重及各项生产性能都有了显著提高（P＞0．01）,西本杂初生重、6月龄、12月龄、18月龄、24月龄体重比本地牛分别提高了21．75％、49．98％、45．41％和37．63％,改良效果明显。     

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.