光合细菌在奶牛、肉牛饲养中应用的试验

光合细菌（photosynthetic becteria）是一类有益微生物，含有丰富的优质蛋白质、多种维生素、生物素、类胡萝卜素、钙、磷及多种微量元素，特别富含多种生理活性物质，如：促生长因子，免疫调节因子，辅酶Q10等，是近年开始发展的新型优质饲料添加剂，在各种水产养殖及鸡猪等禽畜养殖中有很多成功的应用试验，并得到一定的推广、。为进一步发展光合细菌应用于大牲畜，为农业现代化服务，我们进行了光合细菌在奶牛、肉牛饲养中的应用试验，取得了良好的效果。一、材料和方法⒈ 光合细菌制剂为深泽光合生物实验厂生产的“红精灵”饲宝，该产…     

光合细菌在奶牛饲养中应用的试验

本文报道了对不同生理时期的奶牛及患胃肠病奶牛的饲料中加喂光合细菌的试验，结果表明每天每头牛加喂２５０￣３００ｍｌ光合细菌（成本１．２５－１．５元），７日后显效，平均每天每头牛多产奶３公斤。病牛９日后症状消失，恢复产奶，经济效益明显，具有推广价值。     

光合细菌在奶牛饲养中的应用效果

对不同生理时期的奶牛及患胃肠病奶牛的饲料中加喂光合细菌，结果表明每天每头牛加喂250～300mL光合细菌（成本1,25-1．50元），6d后平均每天每头牛多产奶3-5kg。病牛7d后症状消失，恢复产奶，经济效益明显。具有推广价值。     

光合细菌在奶牛饲养中的应用效果

对不同生理时期的奶牛及患胃肠病奶牛的饲料中加喂光合细菌试验,结果表明每天每头牛加喂250～300ml光合细菌(成本1.25～1.5元),6d后显效,平均每天每头牛多产奶3～5kg。病牛7d后症状消失,恢复产奶,经济效益明显,具有推广价值。     

光合细菌在奶牛饲养中的应用效果

本试验是对不同生理时期的奶牛及患胃肠病奶牛的饲料中加喂光舍细菌的试验。结果表明每天每头牛加喂250～300ml光合细菌(成本1．25～1．5元)，6d后显效，平均每天每头牛多产奶3～5kg。病牛7d后症状消失，恢复产奶，经济效益明显，具有推广价值。     

光合细菌在肉鸡饲养中的应用试验

光合细菌(photosynthetic Bacteria简称PSB)属红螺菌种细菌.其菌体本身含有60％以上的蛋白质,并含有丰富的维生素、促生长因子、抗病毒活性因子、辅酶Q等多种生理活性物质.本试验旨在研究PSB对肉用仔鸡的促生长作用和防病抗病作用,以提高我区肉鸡生产的经济效益。本试验进行了初试与中试。     

光合细菌添加剂饲养蛋鸡试验

光合细菌添加剂饲养蛋鸡试验江苏省如东职业高中陈德华江苏省南通市第二兽药厂吉林，朱建光合细菌是一类能进行光合作用的水生细菌，可利用光能进行不产氧的光合作用，而合成菌体自身生长、繁殖所需要的各种养料。据分析，干菌体中含蛋白质６５％～６６％，氨基酸品种齐全...     

光合细菌在肉鸡饲养中的应用

光合细菌（简称ＰＳＢ）是一类水生有益微生物,属红螺菌,其营养丰富,蛋白质含量高达６５％以上,并富含各种维生素、氨基酸及抗病因子等,本文旨在探讨ＰＳＢ添加于肉鸡饲料中的应用效果。１　材料与方法　１．１　试验用肉鸡　８５０羽２３日龄ＡＡ肉仔鸡,由东台市许河镇官洋村养鸡专业户余荣来提供,平均体重１．０７千克。１．２　ＰＳＢ　由东台市科委提供,无锡海得生物工程有限公司生产,每毫升含活菌数３×１０９,淡红色液体。１．３　饲料及饲养方法　饲料由玉米６４％、豆饼３１％、浓缩料５％组成。每千克饲料含代谢能２．９…     

Thiamphenicol pharmacokinetics in beef and dairy cattle

The pharmacokinetics of thiamphenicol were investigated in 10 calves and six lactating cows. It was found that this drug is rapidly absorbed (1 5 min) following intramuscular injection with an absorption rate constant and a bioavailability of 8.7 h^-1 and 84%, respectively. The drug appears to be widely distributed into various body fluids, yielding a volume of distribution (V_d(area)) of approximately 0.9 l/kg. The micro-rate constants indicated that the antibiotic rapidly diffuses into the peripheral compartment (k₁₂ > k₂₁). Elimination from plasma is relatively rapid, with a biological half-life of about 1.75 h. Thiamphenicol appears shortly in milk (15 min) after its intravenous administration, and gives milk to plasma concentration ratios greater than one between 4 and 12 h.     

Antimicrobial resistance in beef and dairy cattle production

Observational studies of cattle production systems usually find that cattle from conventional dairies harbor a higher prevalence of antimicrobial resistant (AMR) enteric bacteria compared to organic dairies or beef-cow operations; given that dairies usually use more antimicrobials, this result is not unexpected. Experimental studies have usually verified that application of antimicrobials leads to at least a transient expansion of AMR bacterial populations in treated cattle. Nevertheless, on dairy farms the majority of antibiotics are used to treat mastitis and yet AMR remains relatively low in mastitis pathogens. Other studies have shown no correlation between antimicrobial use and prevalence of AMR bacteria including documented cases where the prevalence of AMR bacteria is non-responsive to antimicrobial applications or remains relatively high in the absence of antimicrobial use or any other obvious selective pressures. Thus, there are multi-factorial events and pressures that influence AMR bacterial populations in cattle production systems. We introduce a heuristic model that illustrates how repeated antimicrobial selection pressure can increase the probability of genetic linkage between AMR genes and niche- or growth-specific fitness traits. This linkage allows persistence of AMR bacteria at the herd level because subpopulations of AMR bacteria are able to reside long-term within the host animals even in the absence of antimicrobial selection pressure. This model highlights the need for multiple approaches to manage herd health so that the total amount of antimicrobials is limited in a manner that meets animal welfare and public health needs while reducing costs for producers and consumers over the long-term.     

The seroprevalence of Johne's disease in Georgia beef and dairy cull cattle.

Beef and dairy cattle serum samples, collected during 2000 at sale barns throughout Georgia, were obtained from the Georgia State Brucellosis Laboratory and were used to conduct a retrospective epidemiological study. Statistical samplings of 5,307 sera, from over 200,000 sera, were tested for antibodies to Mycobacterium avium ssp. paratuberculosis, (Johne's disease) using a commercial enzyme-linked immunosorbent assay test kit. An overall period seroprevalence in all classes of cattle tested was 4.73%. The period seroprevalence in dairy cattle was 9.58%, in beef cattle it was 3.95%, and in cattle of unknown breed it was 4.72%. It was concluded that the seroprevalence of Johne's disease in cull beef and dairy cattle in Georgia is economically significant.     

The economic consequences of beef crossing in dual-purpose or dairy cattle populations

The total benefit from·beef crossing in a dairy or dual-purpose cow population is (0.68)KM'_bN, where K is the proportion of cows crossed to beef bulls, M'_b is the net economic superiority of beef cross progeny over straight dairy or dual-purpose progeny as beef animals and N is the total number of inseminations. For relatively modest values of K and M'_b, this benefit is shown to be greater than the total cost of the A.I. service. The second consequence of beef crossing is to concentrate the dairy merit transmitted into fewer inseminations. This raises their average genetic value and increases the return for investment in dairy testing and selection.     

肉牛和奶牛家庭牧场发展现状与对策

为保证我国肉牛养殖业和奶牛养殖业的高速发展,经过多种养殖模式的对比,发现以家庭为主体集约化生产、商品化经营的家庭牧场更加适合未来畜牧业的发展趋势,我们认为肉牛和奶牛的家庭牧场式养殖已经成为我国畜牧业未来的发展方向之一。本文对我国肉牛和奶业发达国家的奶牛的家庭牧场发展现状进行了分析,并与畜牧业发达国家的家庭牧场进行对比,总结了我国家庭牧场在发展中存在的问题,并针对这些问题提出了未来我国家庭牧场的发展对策,以期促进我国肉牛和奶牛的家庭牧场持续健康发展。     

不同青饲料饲喂泌乳奶牛试验

试验选择年龄、胎次、体重、体况、产奶量相近的奶牛20头，随机分为4组（即对照Ⅳ组、试验Ⅰ、Ⅱ、Ⅲ组），每组5头，进行为期40d的饲养试验，其中包括lOd的预试期。试验Ⅰ、Ⅱ、Ⅲ组的饲料配方是在对照Ⅳ组的基础上，分别用WL－323紫花苜蓿、普那菊苣和特高黑麦草替代野青草。试验结果表明：几种牧草均能显著提高泌乳奶牛的产奶性能，其中WL－323紫花苜蓿、普那菊苣显著优于特高黑麦草，特高黑麦草显著优于野青草。Ⅰ－Ⅳ组的牛奶饲料成本差异显著，分别为0．83元/kg、0．84元/kg、0．87元/kg、0．93／kg。     

Seroprevalence of Neospora caninum infection in dairy and beef cattle in Paraguay

Seroprevalence of Neospora caninum in 879 beef and dairy cattle in different locations of Paraguay was determined by an ELISA. In the survey, 262 (29.8%) cattle were positive to N. caninum, and animals with anti-Neospora antibody titre were observed in all the locations tested in the country. Serum samples taken from a herd that exhibited persistent abortion had the highest percentage of animals being positive to the parasite (17/30, 56.7%). In the same herd, abortion was significantly more likely in animals with high anti-Neospora antibody titre. Immunoblot analysis demonstrated that the banding pattern from positive Paraguayan cattle was similar to that seen with the positive control sample. In conclusion, N. caninum infection is present among Paraguayan beef and dairy cattle, and it may be an important cause of bovine abortion in Paraguay.     

Seroprevalence of neosporosis in beef and dairy cattle breeds in Northeast Hungary

In order to assess the seroprevalence of bovine neosporosis with indirect fluorescent antibody test (IFAT), blood samples were collected randomly from 1063 beef and dairy cattle belonging to 12 different breeds in Northeast Hungary. Antibodies to Neospora caninum were detected in 27 (2.5%) of the animals, kept on 19 of the 42 settlements included in this survey. Since samples were collected on 50 farms, herd prevalence amounted to 38%. The percentage of cattle with seroconversion increased with age, suggesting a postnatal source of infection. The highest rate of positivity was detected in Aberdeen Angus (3.3%) and Holstein-Friesian cows (3.2%), and the lowest in Limousine (0.9%), but no breed predisposition was statistically substantiated. Neosporosis was more prevalent in dairy (3.4%) than in beef (1.9%) cattle, although the difference was not significant. Only three out of the seropositive cows, all of them Holstein-Friesians, had a history of abortion.     

Cumulative discounted expressions of dairy and beef traits in cattle production systems

Gene-flow methodology was used to calculate the cumulative discounted expressions (CDE) for annual/lactation, replacement heifer, cull cow, birth, yearling, and slaughter traits in alternative cattle production systems. Generic equations were presented and parameters representing dairy-beef production systems in Ireland and Brazil were inputted. Cumulative discounted expressions using input parameters from a hypothetical purebred dairy production system with poor cow longevity were also calculated. Cumulative discounted expressions were calculated assuming either an initial purebred or crossbred mating within each production system. Absolute and relative differences in CDE existed among trait categories across the three alternative production systems investigated. For example, the CDE of beef-related traits accruing from an initial purebred mating ranged from 0.42 to 0.75 CDE of an annual/lactation trait across the three contrasting systems investigated which differed in various input parameters. Such variation may alter the relative emphasis of traits on overall profitability thereby contributing to genotype by environment interactions. The results of this study highlight the necessity to consider auxiliary traits in sire selection over and above those representing the principal intended use of the sire. This was particularly so for integrated dairy-beef cattle production systems.     

Comparison of enzyme activities in plasma and leukocytes in dairy and beef cattle

Concentrations of plasma glucose, immunoreactive insulin (IRI) and free fatty acid (FFA) and activities of enzymes related to energy metabolism and lactate dehydrogenase (LDH) isoenzyme pattern in plasma and leukocytes were investigated in lactating Holstein cows (dairy cattle) and fattening Japanese Black Wagyu x Holstein steers (beef cattle). IRI concentrations and LDH and malate dehydrogenase (MDH) activities in the plasma of beef cattle were significantly higher than those in dairy cattle. The cytosolic ratio of MDH/LDH activity in the leukocytes of beef cattle was significantly higher than that of dairy cattle. These findings might be associated with the different energy metabolism between dairy and beef cattle.