苜蓿青贮过程中三种酶活性动态研究

采用单因素完全随机设计探索苜蓿青贮过程中蛋白降解酶活性规律,以及甲酸对蛋白降解酶活性的抑制效果.结果表明,在没有添加剂的情况下,苜蓿青贮过程中氨基肽酶、酸性蛋白降解酶活性均随着青贮时间的延长呈现下降趋势,且羧基肽酶对蛋白的降解起到主导作用,通过添加5.0g· kg-1 FW甲酸,能够有效抑制羧基肽酶的活性,起到了抑制苜蓿青贮过程中蛋白分解的作用.     

苜蓿青贮过程中蛋白的分解及抑制方法

苜蓿Medicago sativa在青贮过程中由于自身蛋白酶的作用使蛋白分解产生非蛋白氮(NPN)而造成的蛋白损失非常严重.介绍了苜蓿青贮时蛋白的分解机理、影响蛋白分解的因素和青贮时各种添加剂对蛋白分解的影响以及目前抑制苜蓿在青贮过程中蛋白分解的研究动态,并提出了今后研究苜蓿青贮时抑制蛋白分解需要解决的问题.     

苜蓿丝氨酸蛋白水解酶及青贮时对蛋白降解作用的研究

本研究以苜蓿(Medicago sativa)绿汁发酵液形式模拟青贮的发酵过程,探讨了苜蓿中丝氨酸蛋白酶的特性及其在苜蓿青贮过程中对蛋白的降解作用.在制作苜蓿绿汁发酵液前通过添加丝氨酸蛋白水解酶抑制剂(PMSF)并设置对照组来分析其在形成非蛋白氮各组分中的作用.结果表明,苜蓿中的丝氨酸蛋白酶最适pH值为6.6,最适温度...     

水分和添加剂对苜蓿青贮效果的影响

为研究苜蓿的水分、添加剂对苜蓿青贮发酵品质的影响,通过对头茬苜蓿设置3个水分梯度,并添加4个水平的甲酸、丙酸、双乙酸钠,装入聚乙烯袋抽真空,发酵45 d 后进行营养分析和品质鉴定。结果表明：适宜苜蓿青贮的水分条件为55%,这一水分条件下苜蓿青贮料的 pH、氨态氮、粗纤维最低,可溶性糖、乳酸最高;而3种添加剂对青贮料的影响具体表现为：与对照组相比,能够显著降低苜蓿青贮料的 pH 和氨态氮含量（P 〈0.05）,并且能够很好地保存青贮料中的可溶性糖,通过对灰色关联度分析,甲酸对苜蓿青贮的影响效果最佳,丙酸次之;且55%的水分条件下添加15 mL/kg 的甲酸,青贮效果为最好。     

两种牧草在青贮过程中氮转化动力学的比较

为了研究植物酶和微生物活性对青贮牧草蛋白质降解的影响,本试验评估了紫花苜蓿和红花苜蓿在青贮过程中的氮素转化动力学。方法 :试验制备了紫花苜蓿和红花苜蓿青贮饲料,并将其平均分为2组,其中1组用放射处理,另1组作为对照,即试验共有4组:未经放射的紫花苜蓿青贮饲料、放射处理的紫花苜蓿青贮饲料、未放射的红花苜蓿青贮饲料和放射处理的红花苜蓿青贮饲料。分别在青贮1、4、8和30 d后进行发酵质量和氮成分分析。结果 :放射处理通过提高pH抑制微生物活性,但对发酵产物无显著影响(P 0.05)。除肽氮外,所有氮组分在整个青贮过程中均有增加(P 0.05)。红花苜蓿青贮料与紫花苜蓿青贮料相比,蛋白质水解降低,青贮前期肽氮和游离氨基酸氮的增加量显著降低(P 0.05)。放射处理显著提高了紫花苜蓿青贮第1天的肽氮和氨基酸氮含量(P 0.05),这两种氮元素在未放射的青贮饲料中含量均高于放射处理组(P 0.05)。未放射的紫花苜蓿青贮饲料中氨氮和非蛋白氮含量最高(P 0.05),放射处理的红花苜蓿青贮饲料中氨氮和非蛋白氮含量最低(P 0.05)。结论 :红花苜蓿和紫花苜蓿的氮素转化模式不同,特别是在青贮期。微生物活性在蛋白质水解中起一定作用,与紫花苜蓿相比,红花苜蓿受多酚氧化酶的影响较小。     

坡位及接种剂对苜蓿青贮品质及CNCPS蛋白组分的影响

分别以种植在上坡、中坡和下坡处的苜蓿品种中苜1号为原料,设置植物乳杆菌、复合乳酸菌剂两个接种剂处理,研究坡位和接种剂对苜蓿青贮品质及CNCPS蛋白组分的影响。结果表明,上坡处苜蓿青贮饲料的乳酸、粗蛋白质含量极显著高于另外两种坡位(P0.01),pH值、丁酸、中性洗涤纤维含量极显著低于另外两种坡位(P0.01)。接种剂的使用可以不同程度地降低苜蓿青贮饲料的pH值,减少氨态氮生成,抑制丁酸的产生,提高乳酸和干物质含量。植物乳杆菌可以降低上坡和中坡处的苜蓿青贮饲料的非蛋白氮含量(P0.05),提高中速降解蛋白含量(P0.05)。综上所述,上坡×植物乳杆菌处理的青贮品质较好,且可以保护更多的真蛋白不被降解。     

添加乳酸菌和纤维素酶对苜蓿青贮品质的影响

初花期收获的苜蓿(Medicago sativa)经过0、8、32 h的晾晒,添加乳酸菌和纤维素酶进行青贮。结果表明,苜蓿凋萎（干物质含量为38.45%）青贮可以使青贮料的氨态氮含量显著降低,并保存有更多的粗蛋白质,生成更多的乳酸。苜蓿青贮时添加乳酸菌和纤维素酶能明显改善苜蓿青贮料的发酵品质,即降低青贮料的氨态氮含量和保存更多的粗蛋白质以及生成更多的乳酸。晾晒8 h的苜蓿添加乳酸菌（106 cfu/g）和纤维素酶（0.05 g/kg）的青贮效果最好;而晾晒32 h的苜蓿直接青贮的效果最好。     

玉米粉和食淀粉乳杆菌混合处理对苜蓿青贮品质的影响

试验旨在研究添加玉米粉和食淀粉乳杆菌(Lactobacillus amylovorus)对苜蓿青贮品质的影响。试验采用析因设计,选取4个玉米粉添加量(占鲜重的0%、3%、6%、9%),3株不同食淀粉乳杆菌[L.amylovorus KM112088(L_1)、L.amylovorus KM112091(L_2)和L.amylovorus KM112089(L_3)]以及不接种处理,共计16个组(4×4),青贮35 d后开封,分析不同处理对苜蓿青贮品质的影响。结果表明,苜蓿单独青贮发酵品质较差;单独添加玉米粉,随着添加量的增加,苜蓿青贮的p H值以及氨态氮的含量显著下降(P<0.05),苜蓿青贮品质显著改善,但玉米粉中的淀粉降解较少;单独添加L.amylovorus处理中,虽然L_2处理组显著降低苜蓿青贮的氨态氮含量(P<0.05),提高乳酸和乙酸质量比,但对苜蓿青贮品质的改善效果较小;混合添加玉米粉和L.amylovorus,淀粉被有效降解和利用,且L_1和L_2与玉米粉混合处理组的苜蓿青贮品质得到显著改善(P<0.05),在复合添加3%的玉米粉时,即可获得优于单独添加9%玉米粉的发酵品质。综上所述,在苜蓿青贮实践中,可通过复合添加3%玉米粉和L_1或L_2,来提高玉米粉的添加效果,改善苜蓿青贮的发酵品质。     

单一和复合乳酸菌添加水平对苜蓿青贮营养品质及蛋白组分的影响

以第1茬现蕾期刈割的紫花苜蓿(Medicago sativa)为原料(干物质含量为42.56%),结合康奈尔碳水化合物-蛋白质体系(CNCPS),研究不同浓度的单一和复合乳酸菌对苜蓿青贮品质及蛋白组分的影响。发酵40d后取样分析其青贮发酵品质和营养成分,结果表明,所有乳酸菌处理组都能显著降低苜蓿青贮饲料的氨态氮含量(P0.05),并且均未检测到丁酸;添加量为1×10~7 cfu·g~(-1)的单一乳酸菌处理组氨态氮含量最低,乳酸含量最高;除添加量为1×10~5cfu·g~(-1)的复合菌处理组外,其它乳酸菌处理组的pH均显著低于无添加剂处理组(P0.05);乳酸菌处理后粗蛋白含量无显著变化(P0.05);复合菌处理组的非蛋白氮含量显著低于无添加剂处理组(P0.05);单一和复合乳酸菌都能降低蛋白组分中的非蛋白氮(PA)含量,增加快速降解真蛋白质(PB1)和中速降解真蛋白质(PB2)含量,复合菌处理的真蛋白质(PB)含量显著高于对照的(P0.05)。综上所述,高浓度的单一植物乳杆菌(Lactobacillus plantarum)处理的苜蓿青贮发酵品质最好,复合菌能保护更多的真蛋白不被降解。     

青贮红花苜蓿替代豆粕对奶牛营养价值的评估

文章旨在评估全混合口粮用青贮红花苜蓿替代豆粕对瘤胃非降解蛋白和肠道可消化蛋白的影响。试验日粮用不同水平的青贮苜蓿代替豆粕,全混合日粮的粗饲料和浓缩料按照3∶1组成,在干物质基础上,全混合日粮中的青贮苜蓿比例为15%、30%、45%和60%。采用尼龙袋法测定粗蛋白质的瘤胃降解,分别将饲料样品孵育2、8、16、24、32、72 h,日粮瘤胃非降解蛋白含量用2%、5%和8%/h的转运速率表示。此外,将日粮样品在瘤胃中孵育16 h,测定瘤胃非降解蛋白在肠道的消化率。结果显示:随着日粮青贮苜蓿添加水平的升高,快速降解蛋白从26.2 g/kg显著升高至212 g/kg(P 0.05),瘤胃可降解蛋白质从810 g/kg线性降低至676 g/kg(P 0.05)。当转运速率传为8%/h,瘤胃非降解蛋白从315 g/kg线性下降到253 g/kg(P 0.05)。随着日粮青贮苜蓿水平的增加,瘤胃非降解蛋白在十二指肠的消化率从760 g/kg下降到574 g/kg(P 0.05)。粗蛋白质在瘤胃内降解增加,但十二指肠吸收的瘤胃非降解蛋白量从184 g/kg线性下降至79 g/kg(P 0.05)。结果表明,高产奶牛日粮中青贮苜蓿完全替代豆粕不可行。替代水平达到30%时对瘤胃非降解蛋白含量及消化率无显著影响。     

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.     

Prevalence of gastric lesions in racing Alaskan sled dogs

Human and equine athletes are reported to have a high prevalence of gastric disease, and anecdotal evidence suggests a similar phenomenon applies to racing sled dogs. To investigate the prevalence of gastric disease in racing sled dogs, we conducted 2 gastroscopy studies on dogs competing in the annual Iditarod Sled Dog Race. A pilot study of dogs that were either dropped from the 2000 Iditarod Sled Dog Race because of illness or that finished the race indicated that, approximately 5 days after competing, 10 of 28 dogs (35%) had endoscopic evidence of gastric ulceration, erosion, or hemorrhage. The next year, an endoscopic study of 73 dogs participating in the 2001 Iditarod race was performed in order to evaluate a larger population of dogs. Data from 70 of these dogs could be used; 34 (48.5%) had ulceration, erosion, gastric hemorrhage, or some combination of these findings. When this group of 70 dogs was compared retrospectively to a control group of 87 dogs presented to the Texas A&M University (TAMU) Veterinary Medical Teaching Hospital, the Iditarod sled dogs had a significantly higher prevalence (P = .049) of gastric lesions. These findings suggest that, similar to athletes of other species, elite canine athletes have an increased prevalence of gastric disease compared to the canine population at large.     

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     

Avian brood parasitism — a growing research area in behavioral ecology (part Ⅱ)

正We are pleased to publish the second special issue on avian brood parasitism and to be responsible guest editors for the two special issues of Chinese Birds (Vol. 3, No. 4, 2012 and Vol. 4, No. 1, 2013), entitled "Avian Brood Parasitism - A Growing Research Area in Behavioral Ecology". The first issue was published in December 2012. The goal of the two special issues is to publish accumulated knowledge and some of the recent developments in     

Internal Parasites and Haematological Values in Cattle Slaughtered in Buea Subdivision of Cameroon

Tropical Animal Health and Production -