Brucellosis among smallholder cattle farmers in Zambia

A cross-sectional study was performed in Southern and Lusaka provinces of Zambia between March and September 2008 to estimate Brucella seroprevalence in cattle kept by smallholder dairy farmers (n = 185). Rose Bengal test (RBT) was used as a screening test followed by confirmation with competitive ELISA (c-ELISA). We investigated 1,323 cattle, of which 383 had a history of receiving vaccination against brucellosis and 36 had a history of abortion. Overall seroprevalence was 6.0% with areas where vaccination was practiced having low seroprevalence. Age was associated with Brucella seropositivity (P = 0.03) unlike cattle breed (P = 0.21) and sex (P = 0.32). At area level, there was a negative correlation (Corr. coeff = −0.74) between percentage of animals with brucellosis vaccination history (vaccination coverage) and level of brucellosis; percentage of animals with history of abortion (Corr. coeff. = −0.82) and brucellosis vaccination coverage. However, a positive correlation existed between brucellosis infection levels with percentage of animals having a history of abortion (Corr. coeff. = 0.72). History of vaccination against brucellosis was positively associated with a positive Brucella result on RBT (P = 0.004) whereby animals with history of vaccination against brucellosis were more likely to give a positive RBT test results (OR = 1.52). However, the results of c-ELISA were independent of history of Brucella vaccination (P = 0.149) but was positively associated with history of abortion (OR = 4.12). Our results indicate a relatively low Brucella seroprevalence in cattle from smallholder dairy farmers and that vaccination was effective in reducing cases of Brucella infections and Brucella-related abortions. Human exposure to Brucella through milk from smallholder farmers could result through milk traded on the informal market since that milk is not processed and there no quality and safety controls.     

Mortality and commercial off-take rates in adult traditional cattle of Zambia

A cohort study was conducted in the livestock-wildlife interface areas of Zambia to determine cattle mortality and commercial off-take rates among adult cattle as well as factors influencing them. A total of 416 animals from 43 herds were followed up for one year and animals were individually identified and their fate was indicated as sold, slaughtered, dead or present as appropriate. The overall mortality incidence risk was estimated at 7.5%. Cattle in Kazungula were at a greater risk of dying compared to those in Blue Lagoon and Lochnivar. Annual off-take was estimated at 13.7% (8.1–19.3%), unadjusted values, and 16.4% (8.1–24.5%) after adjusting for sampling fraction in primary sampling units (herds) and area stratification. Area variations were observed with Kazungula recording the highest in both instances, which was attributed to a contagious bovine pleural pneumonia (CBPP) outbreak. Herd size and gender were observed to influence cattle mortality rates. Cattle in the middle-sized herds (50–150 cattle) recorded high mortality rates (OR = 3.91) compared to smaller herds (10–50) and so were females compared to males (OR = 4.16). The logistic regression model showed that cattle death was influenced by managerial factors and that off-take rates tend to increase in the face of disease outbreaks.     

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.     

Practices and opinions of New Zealand beef cattle farmers towards bovine viral diarrhoea control in relation to real and perceived herd serological status

ABSTRACT

Aims: To investigate the seroprevalence of infection with bovine viral diarrhoea (BVD) virus among 75 beef herds and seroconversion in cattle during early pregnancy, and to determine the practices and opinions of farmers towards BVD control and their association with real and perceived herd serological status.

Methods: Blood samples were collected before mating in 75 beef herds across New Zealand from 15 unvaccinated heifers that had delivered their first calf that season. Serum samples were tested for BVD antibodies using ELISA individually, and after pooling samples for each farm. Animals that were antibody-negative were retested at either pregnancy diagnosis or weaning. Farmers were asked to complete a detailed survey about herd demographics, BVD testing and vaccination practices, and opinions towards national BVD control.

Results: Based on the pooled serum antibody ELISA results, there were 28/75 (37%) negative herds, 15/75 (20%) suspect herds, and 32/75 (43%) positive herds. Of 1,117 animals sampled 729 (65.3%) tested negative for BVD virus antibodies; when retested, 47/589 (8.0%) animals from 13/55 (24%) herds had seroconverted. Among 71 famers providing survey responses 11 (15%) believed their herd was infected with BVD, 24 (34%) were unsure and 36 (51%) did not think their herd was infected. Only 19/71 (18%) farmers had performed any BVD testing within the past 5 years and 50/70 (71%) had not vaccinated any cattle for BVD. Support for national BVD eradication programme was strong in 51/71 (56%) respondents, but the biggest challenge to BVD control was considered to be famer compliance. Compared to farmers who did not think their herd was infected, more farmers who thought BVD was present in their herds had previously tested for BVD, would consider testing all replacement calves, and would support establishing a national BVD database; fewer would consider purchasing BVD tested or vaccinated cattle only.

Conclusions and clinical relevance: Only 15% of the beef farmers in this study believed their herds were infected with BVD virus and few of them had undertaken BVD screening. Nevertheless many were supportive of implementing a national BVD control programme. It is likely that the lack of farmer awareness around BVD and the failure of farmers to recognise the potential impacts in their herds are hindering progress in controlling the disease in New Zealand. There are opportunities for New Zealand veterinarians to be more proactive in helping beef farmers explore BVD management options.     

Crossbreeding cattle in beef production programmes in Kenya

Data collected on a privately owned ranch located in the Machakos District of Kenya at approximately 2 degrees latitude south of the equator at an elevation varying from 1,675 to 2,000 m were analysed on five breed groups of cows: (1) purebred Boran, (2) 1/2 Charolais-1/2 Boran (1/2 C-1/2 B), (3) 3/4 Boran-1/4 Charolais (3/4 B-1/4 C), (4) 1/2 Ayrshire-1/2 Boran (1/2 A-1/2 B) and (5) 1/2 Santa Gertrudis-1/2 Boran (1/2 SG-1/2 B). The maternal traits evaluated included age at first calving, calving interval, calf weight at weaning and cow productivity index (calf weight weaned annually per cow calving). Mean cow productivity index for all cows was 192 kg; for purebred Boran, 174 kg; for 1/2 C-1/2 B, 200 kg; for 3/4 B-1/4 C, 191 kg; for 1/2 A-1/2 B, 210 kg; and for 1/2 SG-1/2 B, 185 kg. Cow breed groups 1/2 C-1/2 B, 3/4 B-1/4 C, 1/2 A-1/2 B and 1/2 SG-1/2 B exceeded (P less than 0.01) purebred Boran by 14.9, 9.8, 20.7 and 6.3%, respectively, in cow productivity index.     

Perception of cattle farmers of the efficacy of east coast fever immunization in Southern Zambia

A study using a structured questionnaire was conducted to assess the perception of cattle farmers of the efficacy of East Coast fever (ECF) immunization in southern Zambia. One hundred and seventy-nine farmers from five districts in southern Zambia were interviewed. The majority of farmers (85%) perceived ECF immunization as being very effective and about half of them (51.4%) preferred immunization to other ECF control strategies. The study showed that the number of calves immunized was strongly associated with the farmer's perception of the benefits of immunization. There was no association between the number of calves immunized and the number of veterinary assistants in a given district or their transport situation. Overall mortality in ECF-immunized calves from various causes stood at 4.2%. Based on farmers' reports, the majority of these deaths seemed to have been caused by anaplasmosis, another tick-borne disease, and might have resulted from relaxation of tick control after ECF immunization. The reasons identified by farmers for not immunizing their animals included failure by immunizing teams to reach certain areas, not having calves of immunization age, and lack of money. These findings provide valuable information on how livestock farmers perceive and adopt new animal disease control strategies and the information could be useful in their planning and implementation.     

纤维素酶在肉牛生产中的研究与应用

自从1906年纤维素酶首次在蜗牛的消化液中被发现以来，纤维酶的研究就受到动物营养界的普遍关注。进入上世纪90年代，世界能源的匮乏促使纤维素酶的研究重点转向开辟新能源方面。反刍动物日粮以粗饲料为主，但是我国目前优质牧草的缺口很大，因而极大地限制了     

HACCP模式在肉牛安全生产中的应用

HACCP是迄今为止食品安全生产方面最有效、最科学的质量管理方法之一。本文根据HACCP的技术规程,对肉牛生产的各流程进行分析,确定了肉牛生产过程中的关键控制点,并提出了控制措施。     

超敏蛋白复合酶在肉牛生产中的应用

[目的]试验将超敏蛋白复合酶添加于肉牛生产中的母牛繁育和肉牛育肥环节,研究其应用效果。[方法]试验选择平均怀孕45 d左右的同批次怀孕母牛28头,随机均分为试验A1组和对照A2组,选择育肥青年牛78头,随机均分为试验B1组和对照B2组。对照A2组和B2组按照原来的饲料配方饲喂,试验A1组和B1组在原有的基础上添加精饲料1‰的超敏蛋白复合酶进行饲喂。[结果]试验结果表明,怀孕母牛的试验组相较于对照组产活仔数多1头,出生均重差为7.58 kg, 60日龄断奶均重差为12.55 kg;育肥青年牛的试验组相较于对照组增重大幅提升,育肥期平均增重差为84 kg。[结论]超敏蛋白复合酶在肉牛生产的母牛繁育、青年牛育肥方面均表现出卓越成效,经济效益明显提高。     

Genetic antagonism between body weight and milk production in beef cattle

Korean cattle have an unusually short suckling period (4 mo) due to poor milking ability, and this is a hindrance to growth of calves. Therefore, Korean cattle breeders have shown interest in genetic improvement of milking ability. In this study, body weight (birth weight, weaning weight, and yearling weight) and five daily milk yields by period in Korean cattle (Hanwoo) were analyzed using a two-trait sire and maternal grandsire mixed model. The milk yields used were actually measured at sequential intervals from 1 to 4 mo after calving. Posterior means of the parameters were estimated using Gibbs sampling. Heritability estimates (0.25 to 0.26) for daily milk yield at weaning were larger than those with other periods. Genetic impact on daily milk yield, especially at weaning, was emphasized in order to lengthen the suckling period of Korean cattle. Genetic correlation estimates between BW and daily milk yield were all negative (-0.08 to -0.16 for birth weight, -0.04 to -0.21 for weaning weight, and -0.12 to -0.19 for yearling weight), whereas environmental correlation estimates were all positive (0.20 to 0.39 for birth weight, 0.34 to 0.51 for weaning weight, and 0.30 to 0.45 for yearling weight). The negative estimates of genetic correlation between weight and milk yield implied genetic antagonism between direct and maternal effects for weaning weight of beef cattle.     

中药方剂及黄芪素对奶牛乳房炎及其生产性能的影响

选择产奶牛237头，平均质量（600±151）kg，按照泌乳量相近的原则分为黄芪素组、中药组和对照组，考察中药和中药提取物（黄芪素）对奶牛乳蛋白率、乳脂率、产奶量、体细胞数和乳房炎发病率的影响。结果表明，中药和黄芪素对乳蛋白率、乳脂率和产奶量影响差异不显著；中药组用药前后比较，其奶牛乳房炎检出率由用药前的8．33％下降到2．09％，比黄芪素组下降5．41％，比对照组下降3．61％，比其他产奶牛下降4．02％。中药组预防奶牛乳房炎效果明显（P〈O．05）。     

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.     

Genetic relationships between calving performance and beef production traits in Piemontese cattle

The aim of the study was to obtain estimates of genetic correlations between direct and maternal calving performance of heifers and cows and beef production traits in Piemontese cattle. Beef production traits were daily gain, live fleshiness, and bone thinness measured on 1,602 young bulls tested at a central station. Live fleshiness (six traits) and bone thinness were subjectively scored by classifiers using a nine-point linear grid. Data on calving performance were calving difficulty scores (five classes from unassisted to embryotomy) routinely recorded in the farms. Calving performance of heifers and cows were considered different traits. A total of 30,763 and 80,474 calving scores in first and later parities, respectively, were used to estimate covariance components with beef traits. Data were analyzed using bivariate linear animal models, including direct genetic effects for calving performance and beef traits and maternal genetic effects only for calving performance. Due to the nature of the data structure, which involved traits measured in different environments and on different animals, covariances were estimated mostly through pedigree information. Genetic correlations of daily gain were positive with direct calving performance (0.43 in heifers and 0.50 in cows) and negative with maternal calving performance (-0.23 and -0.28 for heifers and cows, respectively). Live fleshiness traits were moderately correlated with maternal calving performance in both parities, ranging from 0.06 to 0.33. Correlations between live fleshiness traits and direct calving performance were low to moderate and positive in the first parity, but trivial in later parities. Bone thinness was negatively correlated with direct calving performance (-0.17 and -0.38 in heifers and cows, respectively), but it was positively correlated to maternal calving performance (0.31 and 0.40). Estimated residual correlations were close to zero. Results indicate that, due to the existence of antagonistic relationships between the investigated traits, specific selection strategies need to be studied.     

A survey of beef cattle farmers in New Zealand,examining management practices of primiparous breeding heifers

AIM: To obtain an estimate of the incidence of assistance at calving in primiparous (first-calving) beef heifers and the prevalence of breeding heifers at 15 months of age in New Zealand in 2006,and to identify factors contributing to farmers' decisions regarding breeding strategies for heifers, using a survey of beef cattle farmers.

METHODS: A questionnaire was sent to farmers listed in a Massey University database and to members of selected breed societies, as well as published in an industry newspaper; 331 valid responses were received. Information was gathered on the age and number of primiparous heifers, number of heifers assisted, and the importance of various reasons for and against breeding heifers at 15 months of age. Respondents were also required to outline the criteria used for selecting bulls to join with heifers, and the strategies used to manage dystocia in primiparous heifers.

RESULTS: Sixty-five (95% CI=58–71)% of respondents had only 2-year-old primiparous heifers in 2006, whilst a further 11 (95% CI=8–16)% had both 2- and 3-year-old primiparous heifers. The mean reported incidence of assisted calving was 7.0 (95% CI=6.4–7.5)% for 2-year-old primiparous heifers and 1.7 (95% CI=1.2–2.2)% for 3-year-old primiparous heifers. The reported incidence of assistance at calving within individual herdsranged from 0 to 100% for 2-year-old heifers. Respondents with bull-breeding herds most commonly observed their primiparous 2-year-old heifers twice daily, whilst respondents with commercial herds most commonly observed them once daily during calving. The most important reason for breeding heifers at 15 months of age was “increased profit”, whereas the most important reason for not breeding them at that age was “concern about rebreeding performance of 2-year-old heifers”. Estimated breeding value (EBV) for birth weight was the factor considered most frequently when selecting bulls to join with maiden heifers; age of bull and body shape of bull were the next most frequently considered factors. Selection of an appropriate bull was the most common strategy used to manage dystocia in 2-year-old beef heifers.

CONCLUSIONS: The majority of respondents calved their heifers at 2 years of age, and “increased profit” was the primary motivator. Concern about the rebreeding performance of 2-year-old heifers was the most important reason among the remainder of respondents for not breeding heifers at 15 months of age. Dystocia in 2-year-old heifers was “not a problem” or “a minorproblem” in most herds, but there was much variation amongst herds.     

The marketing of herd health and production management services on Dutch dairy farms: perceptions of dairy farmers and their veterinary surgeons

A questionnaire-based survey on veterinary herd health and production management services was conducted on 194 specialist dairy veterinarians and 466 dairy farmers. The farmers were randomly selected from greater than 6,000 farmer clients of the surveyed veterinarians. This paper reports these survey findings and the findings of an earlier survey conducted among the veterinarians. The survey included questions on the attributes of the service itself, the practitioners delivering the service, reasons for participation and the expected future of herd health and production management services. Reasons farmers participated in herd health and production management programmes included; access to routine screening of their herd; increasing profits; and receiving regular veterinary advice or solutions to remedy existing problems. Advantages of participation named included: good management support; higher profits; structural solutions to problems; and being better informed. Differences between farming styles were observed, pointing to the different needs and goals of farming styles. Farmers cited high costs and the time investment required as major disadvantages. The proportion of farmers citing these reasons was lower than expected by the veterinarians. In the future, preventive healthcare will be the main reason of farmers to participate. Farmers who are not using the service can potentially be encouraged to engage the services after gaining increased insight into the herd health and management service structure, the planning of activities, the cost-benefit of the service, veterinary surgeons being more co-operative with other farm advisors and veterinarians being more willing to pay attention to quality issues on the dairy farm.     

DDGS和其他来源的粗饲料在肉牛生产上的应用研究

两组试验用来评估当在蒸汽压片玉米（SFC）日粮中添加玉米DDGS和苜蓿干草（AH）或者玉米青贮（CS）的肉牛的胴体品质、瘤胃发酵或日粮代谢的影响。在试验1中,358头体重为353±13kg的杂交母牛被用来评估玉米DDGS和AH（或CS）对肉牛胴体品质的影响,试验日粮分为4组,分别为：SFC-CS日粮,即蒸汽压片玉米（SFC）和11%青贮料（CS）;DDGS-CS日粮,即蒸汽压片玉米（SFC）和11%青贮料（CS）以及25%DDGS;SFC-AH日粮,即蒸汽压片玉米（SFC）和6%AH;DDGS-AH日粮,即SFC和25%DDGS以及6%AH。所有的牛每天自由采食,试验时间为97d。结果显示,饲喂DDGS没有影响肉牛的平均日增重（ADG,P=0.19）、干物质采食量DMI（P=0.14）以及饲料转化率（P=0.67）。饲喂CS的肉牛要比饲喂AH的肉牛的DMI高（P=0.05）,但ADG（P=0.56）和G：F（P=0.63）没有太大差别;各处理组的肉牛热胴体重（HCW）、屠宰率、皮下脂肪厚度以及牛肉产量、质量等级的差别也不大（P〉0.20）;饲喂CS组的肉牛相对饲喂AH肉牛有降低大理石花纹评分分数的趋势。在第2个试验中,12头荷斯坦奶牛用来评估各种日粮的肉牛瘤胃发酵和日粮代谢的差异。结果显示,饲喂后14h所有处理组的肉牛瘤胃pH值低于5.8,饲喂25%的DDGS组的肉牛瘤胃的乙酸和丙酸的比率较低（P=0.02）,但瘤胃乳酸浓度要比未添加DDGS组的高（P=0.02）。饲喂25%的DDGS组的肉牛瘤胃氨气浓度有所下降（P〈0.01）。这说明当在肉牛蒸汽压片玉米日粮中添加DDGS可以提高饲料转化率。