An economic evaluation of breeding systems with selection and crossing of large white and landrace pigs in a closed herd

Computer models of a number of systems for combining the Large White and Landrace pig breeds were developed. These systems were: 1, firstcross; 2, backcross; 3, rotational cross and 4, synthetic. The models incorporated both selection and heterosis. The monetary gains from running these systems for a period of 10 years were estimated as deviations from returns from a Large White control herd.In the absence of selection, heterosis alone gave gains of A$183, $430, $271 and $164 per sow place for systems 1, 2, 3 and 4. Values were increased markedly by selection. Using typical values for the cost and accuracy of selection and optimum structures of the systems, monetary gains were increased with selection to A$1245, $1492, $1258 and $1311 for systems 1, 2, 3 and 4. Sensitivity analyses revealed wide confidence limits for these gains.In all but the largest herds (> 500 sows), the real value of the complex systems (e.g. backcross) is likely to be diminished relative to the simpler systems (e.g. synthetic) because management costs are expected to be higher and optimum herd structures cannot be attained.     

Economic comparison of open and closed nucleus breeding schemes for wool production

Returns on investments in open or closed nucleus breeding schemes to improve clean wool production were examined using Hill's approach of examining the flow of genes through the population.Returns on capital in such schemes are competitive with many alternative investments on the farm if predictions of response are correct. For example, for a typical case considered with heritability of wool weight of 0·4, standard deviation of 0·4 kg, 90% lambs weaned per ewe joined from mature ewes, and 250 cents/kg clean, marginal returns on money invested in labour and materials in the breeding programme in excess of 40% were obtained. The return on the extra investment with an open nucleus using 50% of base-born ewes in the nucleus was about 20%.Returns are sensitive to cost, lambing percentage, price and heritability, the extra returns from the open nucleus becoming more attractive as predicted response or price increases. The value of the gains is not very sensitive to numbers of age groups of ewes or rams.Most of the extra returns go to the commercial flocks, so premiums would need to be paid to the nucleus to provide incentives to maintain the breeding programme.     

基于多尺度感知的高密度猪只计数网络研究

猪只盘点是生猪规模化养殖和管理中的重要环节,人工计数方法费时、费力,在大数据量的猪只盘点中容易出错。本文使用多尺度感知网络对高密度猪群图像中的猪只进行计数。通过对人群计数网络CSRNet的改进,得到猪只计数网络（Pig counting net, PCN）,PCN采用VGG16作为前端网络提取特征,中间层采用空间金字塔（Spatial pyramid）结构对图像中的多尺度信息进行提取与融合,后端网络采用改进的膨胀卷积网络。PCN增加了多尺度感知结构、扩大了后端网络感受野,通过感知多尺度特征得到预测密度图,预测密度图反映了猪只空间分布,通过对密度图积分实现了猪只数量的估计。结果表明,在平均猪只数为 40.71的测试集图像上,PCN的计数准确率优于人群计数网络 MCNN、CSRNet和改进Counting CNN 的猪只计数网络,MAE和RMSE 分别为1.74和 2.28,表现出较高的准确性和鲁棒性;单幅图像平均识别时间为0.108s,满足实时处理要求。     

Simulation of the management of a rabbit population for meat production

A population model for a 100 doe rabbit enterprise was constructed in which the effect on output of various management decisions could be simulated. The question of how many young female stock to retain as replacements for dead or culled breeding stock was examined in detail. The optimum level was found to be when the combined number of mature and immature female replacements was maintained between 25 and 35 replacement does for a population of 100 breeding females. At this level was possible to maintain a regular and predictable output of rabbit carcases. With a larger population of 500 does, the optimum level for the replacement pool remained between 25 and 35 replacement does for each 100 breeding females.     

Simulated effects of changing strategies on production performance of Gobra Zebu cattle

Analyses of various management strategies available for the production of Gobra Zebu cattle at Dahra Research Station were conducted using a dynamic cattle production simulation model. Growth, milk production, forage and management characteristics collected at the station were the major input data used. Effects of the management strategies on production performances were predicted by examining changes in breeding season, breeding age, weaning age and supplementation regimes on productivity indices. The indices used were efficiency of nutrient utilization (ENU), defined as liveweight sold per 100 kg DM consumed, and cow productivity index (CPI), defined as liveweight sold per cow exposed. When females were exposed to calve first at 3 years of age, the ENU (94·4) and CPI (4·04) were highest for breeding from September to November and lowest (77·93 and 3·43, respectively) for breeding from July to September. Weaning at 7 months of age resulted in the highest ENU and CPI (94·89 and 3·95) while weaning at 5 months generated the lowest ENU and CPI (83·93 and 3·58). Among all feeding alternatives, the highest ENU (105·84) and CPI (4·21) were obtained when the entire cow herd was supplemented from May to July. Supplementation of mature cows only was the most desirable strategy among the selective supplemental feeding practices with regard to cow age classes. Results provided valuable guidelines for selecting management practices likely to increase Gobra Zebu productivity.     

Computer assisted management decisions for beef production systems

A linear programming model was developed to determine management policy for a yearly planning horizon on a typical 1320 acre (535 ha) Southern Colorado mountain ranch. Income producing activities (selling cattle and hay and leasing land) and cost activities (buying cattle, borrowing capital, feeding supplements, purchasing fertiliser and fuel, hiring labour and leasing land) were defined for three land types through four seasons.The purpose of the modelling effort was to determine the level of each activity (cow herd size, yearling herd size and area of meadow to be harvested for hay) that resulted in maximum net return for the ranch subject to resource limitation on land, labour and capital. In addition, sensitivity and shadow price analyses revealed expansion options that would be profitable during existing economic conditions.The optimal management plan, using 3 April, 1975 prices, called for grazing 199 head of 450 lb (204 kg) steers and 52 head of 530 lb (240 kg) steers. The plan also called for purchasing and spreading 42 tons (38 MT) of nitrogen and 10 tons (9 MT) of phosphorus on Land I and for growing, harvesting and selling 742 tons (674 MT) of hay. This optimal management plan produced a net return of $27,642. In addition, the optimal plan showed that hay production began replacing beef production when the price of hay was $35·48/ton (39·08/MT) and that the maximum amount of hay was produced with the price increased to $50·00/ton ($55·00/MT).     

半干旱地区保护性耕作技术研究

介绍昌图县的自然概况,提出实施保护性耕作机械化技术是本地区防旱保产的最佳选择,阐述保护性耕作技术的优点及其装备的合理选择。通过实地试验监测,结果表明：在半干旱地区实施保护性耕作机械化技术,可以增收节支、降低成本、提高生产率,达到节本增效的目的,值得大面积推广。     

四川规模猪场产排污系数测定

为探讨四川规模猪场主要污染物排放量、排放规律,本文选择成都附近的一家典型规模养殖场,按照春夏秋冬四个季节,对保育仔猪、育肥猪和繁殖母猪不同饲养阶段生猪的粪、尿量及其COD/TN/TP/铜/锌等污染物进行了周年监测。结果表明,规模猪场不同饲养阶段猪只的粪、尿产生量差异较大,保育仔猪、育肥猪和繁殖母猪每天每头的粪产生量分别为0.45、0.79和1.01 kg,尿产生量分别为1.65、3.47和5.60 kg,不同饲养阶段猪只的固体粪便含水率基本相同,变化范围在62.13%~68.16%,平均含水率65.27%;全氮、全磷、有机质含量基本一致,分别平均为2.68%,2.38%,55.91%;不同饲养阶段猪只的尿液pH值在6.88~7.41之间,偏碱性。育成猪尿液COD值、氨氮、凯氏氮较低,其次为繁殖母猪和保育猪。在此基础上,研究提出规模猪场主要污染物产污系数24个,排污系数18个,为构建四川生猪产排污系数测算方法、摸清全省乃至全国生猪粪污产生量、为国家制定节能减排相关指标等提供科学依据。     

融合体尺信息的封闭式种猪性能测定站设计与试验

针对现有封闭式种猪性能测定站自动化程度不高、无法提供种猪体尺信息等问题,设计了一种集种猪自动识别、体质量自动称量、采食量自动统计、体尺自动测量于一体的封闭式种猪性能测定站。该系统机械部分采用前后端分离设计,通过设计采食门装置和门禁装置为种猪提供封闭测量环境,在此基础上,基于FIR滤波设计了种猪体质量动态称量算法,基于椭圆拟合设计了种猪理想姿态筛选算法,并进一步提出了基于包络分析的种猪体尺测量算法。分别进行了利用实际猪群模拟种猪生长性能验证试验和体尺测量试验,试验验证结果如下：生长性能试验猪群自由采食日均次数8.94次、日均采食时间92.93 min、群体料肉比2.66,Logistic拟合的生长曲线拐点日龄为126.18 d、拐点体质量72.70 kg,符合猪群的生长规律;体尺测量试验中猪群能够筛选出理想姿态帧,体长、体宽、臀宽、体高、臀高等体尺的平均相对检测误差分别为3.69%、2.53%、2.60%、2.59%、2.17%,满足体尺测量要求。试验结果表明,本文设计的封闭式种猪性能测定站可用于种猪的生产性能测定,能够同时提供种猪体质量、采食量和体尺等信息,提高育种效率。     

基于YOLO v3的生猪个体识别方法

为实现高效的猪只个体识别,提出一种基于机器视觉的生猪个体识别方法.通过采集母猪和仔猪个体图像,对图像进行扩充和筛选,制作训练集和测试集.试验采用基于YOLO v3的识别模型,并与Faster RCNN和SSD模型识别结果进行比较,结果表明:对仔猪的识别平均精度均值达89.65％,准确率达95.99％,召回率达84.09...     

基于改进YOLO v5s的经产母猪发情检测方法研究

为解决限位栏场景下经产母猪查情难度大、过于依赖公猪试情和人工查情的问题,提出了一种基于改进YOLO v5s算法的经产母猪发情快速检测方法。首先,利用马赛克增强方式(Mosaic data augmentation, MDA)扩充数据集,以丰富数据表征;然后,利用稀疏训练(Sparse training, ST)、迭代通道剪枝(Network pruning, NP)、模型微调(Fine tune, FT)等方式重构模型,实现模型压缩与加速;最后,使用DIOU＿NMS代替GIOU＿NMS,以提高目标框的识别精度,确保模型轻量化后,仍保持较高的检测精度。试验表明,优化后的算法识别平均精确率可达97.8%,单幅图像平均检测时间仅1.7 ms,单帧视频平均检测时间仅6 ms。分析空怀期母猪发情期与非发情期的交互行为特征,发现母猪发情期较非发情期交互时长与频率均显著提高(P<0.001)。以20 s作为发情检测阈值时,发情检测特异性为89.1%、准确率为89.6%、灵敏度为90.0%,该方法能够实现发情母猪快速检测。     

Environmental and economic impacts of reducing total phosphorous runoff in an agricultural watershed

The economy of northwest Arkansas relies greatly upon livestock and poultry production. The supply of production by-products is increasingly coming under scrutiny as an important source of water pollution in the region. This study uses stochastic dominance techniques to evaluate, environmentally and economically, a range of ten best management practice scenarios to lessen water pollution in the Lincoln Lake watershed. The goal is to generate rankings that could be useful for supporting producers’ and watershed managers’ selection of management practices to reduce total phosphorous losses in runoff. Specifically, this study compares scenarios in terms of net return risk reduction for bermudagrass hay producers.The results showed that environmental and economic rankings differ from each other. Although all scenarios analyzed were effective in reducing total phosphorous losses when compared to a baseline, six of them also decreased net returns. This suggests that including some best management practices may lead to increased net return risk. However, some scenarios were identified that may increase net returns, reduce total phosphorous losses and do not differ considerably from producers’ current management practices.The previous results suggested that the joint environmental-economic impact was important when considering scenarios and that producers’ risk attitudes and best management practices’ economic impacts should be accounted for when selecting scenarios. Producers and watershed managers can weigh trade-offs between total phosphorous losses reduction and net returns variability when making water conservation decisions.     

A simulation model of a breeding ewe flock

A simulation model was constructed of a self-replacing flock of Merino ewes grazing a predominantly Wimmera ryegrass and subterranean clover pasture in the Eppalock catchment of northern Victoria, Australia. The model was used to predict the likely physical, biological and economic consequences of changes in stocking rate and date of lambing.Routines for simulating the local climate, together with expected levels of pasture production, were based on available local data. The herbage produced was utilised for animal maintenance, growth, pregnancy, lactation and wool production. Predictions were made of the ovulation and fertilisation rates of the breeding ewes and the subsequent survival of embryos and lambs. Lamb growth rates were determined relative to their predicted intake levels of milk and herbage.The economic consequences of different combinations of ewe stocking rate and date of lambing were evaluated by simulating the cash flow of the property. Financial returns were obtained from the sale of wool, cast-for-age and culled ewes, and wether lambs.     

粮食安全与农业机械化的逻辑关系及其政策启示——基于三种主要粮食种植成本收益的中美比较

我国2016-2018年稻谷、小麦、玉米种植连续出现亏损.如何增加粮食种植纯收益,提高农民种粮积极性,保障粮食安全?在新冠疫情全球蔓延的特殊时期,粮食安全问题又在我国引起关注.通过比较中美两国三种主要粮食作物种植成本与收益,认为人工成本的攀升是我国粮食种植总成本不断升高的主要原因,提高种植效益的实现路径是通过发展农业机...     

Simulation of production systems in East Africa by use of interfaced forage and cattle models

A forage model and a cattle production model were interfaced and adapted for tropical production conditions in East Africa. The objectives of the modelling were to structure and conceptualise a complex system for better comprehension, thereby determining constraints on a traditional African grazing system. The model was designed to simulate the physical linkages between the scarce resource of forage and the outputs of cattle, meat and milk. The effects of improved management practices were examined for a traditional village livestock grazing system. Verification and validation for the baseline village herd were carried out using several different sources of data. A combination of a restricted breeding season, supplemental feeding during the dry season and a seasonal sales policy resulted in a 40% increase in net revenue to village producers above the baseline for a ten-year period.     

Development of a mathematical model to study the impacts of production and management policies on the herd dynamics and profitability of dairy goats

The reduction in goat milk production and the competitiveness of more profitable activities have increased the adoption of measures to enhance goat milk and meat around the world. A simulation model was built to evaluate the dynamics of a dairy goat herd under different scenarios of production. A System Dynamics approach was used to identify management policies that could affect the behaviour of the herd over 10 years of simulation using data from a dairy goat herd in Brazil. The impact of reproductive and mortality rates, one or two annual reproductive cycles on production, and economic health of dairy goats on changes in the herd dynamics were evaluated. Simulations indicated that small changes in reproduction and mortality rates and milk price can considerably affect the dynamics of the herd as well as the financial health of the production system. The interferences created to visualize the effects were not immediately realized because of intrinsic delays in the system. The comparison of models with one or two breeding seasons indicated that the latter was considerably more profitable and had a faster turnover. It was also found that the two breeding season had a greater capacity to support reduction in milk price that could generate financial instability in the production system. It was concluded that mathematical models can be used to predict impacts in management policies on herd dynamics and sensitivity to support the dairy goat activity showing its viability as an agricultural activity that can contribute to the production and incomes in small farms.     

Replacement policy in dairy herds on farms where heifers compete with cows for grassland: Part 2-Experimentation

Replacement policy is not easy to determine on dairy farms where heifers compete with cows for grassland. Using a computer simulation model of this farm situation, two factorial experiments were conducted to evaluate quantitatively the effect of different replacement rates on profitability and herd improvement.The variables changed in herds of average health and very good health were replacement rate (0·14, 0·22, 0·30), age at first calving (36, 24 months), calving index (13, 12 months) and AI sire merit (standard, premium). Initially, the experimental herd had average health, a replacement rate of 0·22, a calving index of 13 months, calved its heifers at 36 months and had been using standard bulls for many years.After 15 years, the increase in the level of a sinking fund when the age at first calving was reduced was between three and five times greater than when premium bulls were used, calving index was reduced or herd health was improved. There was a major interaction between replacement rate and age at first calving.Yield per cow was significantly reduced (P≤0·001) by reducing the age at first calving and significantly increased when premium bulls (P≤0·001) were used or when herd health was improved (P≤0·05).Some treatments were not tested as expected due to the restraining effect of a 13-month calving interval on the availability of cows for breeding pure in a seasonally calving herd.     

Maasai herd and flock structures in relation to livestock wealth,climate and development

Information was obtained on the structure of the herds and flocks of a sample of 41 households on the three Maasai Group Ranches in Kenya. The purpose of the survey was to contribute to an intensive study of the livestock production system, and also to assess the amount of information that could be obtained from a herd structure study on its own. Differences in herd structure were related to the livestock wealth of the household, the stage of development of the Group Ranch as well as to the variation in climate, and production alternatives.Data from more than 5100 cattle revealed that Maasai herds contained less steers in 1982 (18%) than in 1968 (22%). The proportion of mature steers had also dropped from 5% (1968) to 2% (1982), with maximum valves of 3·2% on the most developed ranch and 2% for the wealthiest stratum of households. A high percentage of females had been retained (56%) giving a herd structure characteristic of subsistence production with milk as a primary output. This structure also caters for a strong market in immature animals and gives the herd a high potential for recovery after a drought. There appeared to be a trend towards increased use of introduced bulls, notably Sahiwal on the Small East African Zebu, with increased Group Ranch Development. However, this trend was confounded by a decreasing aridity gradient with increased development.On two of the ranches for which 1968 counts were available, cattle numbers were 119% of their previous value whereas small stock were 470%. The reason appears to be that increased sedentarisation without adequate range management has resulted in a severe reduction in grasses, and their replacement by forbs. These plants are more palatable to small stock which are better able to exploit the degraded habitat.Information from more than 2730 sheep and 2300 goats revealed that poor households preferred goats and richer households, sheep. The Small East African Goat was ubiquitous, but the most developed ranch had crossed Dorper onto Maasai sheep whereas the least developed and most arid ranch had introduced Somali Blackhead sheep. The Dorper crossbred catered for a market for mutton whereas the Blackhead was primarily for home consumption of fat.The conclusion is that Group Ranch Development has not projected the Maasai into commercial beef ranching as originally planned, but their production system has not stood still. A study of herd structures was a good way of demonstrating the evolution of the system. The method was simple but was dependent for its success on fairly involved and time-consuming sampling and data collection procedures.     

Measuring the costs of African animal trypanosomosis,the potential benefits of control and returns to research

This paper addresses issues surrounding measurement of the potential productivity gains from new livestock technologies and the returns to international livestock research. The approach, applicable to many livestock production constraints and technologies, uses geographic information systems (GIS) to spatially link a biophysical herd simulation model with an economic surplus model. The particular problem examined is trypanosomosis in cattle in Africa, and the potential research product is a multi-component vaccine. The results indicate that the potential benefits of improved trypanosomosis control, in terms of meat and milk productivity alone, are $700 million per year in Africa. The disease now costs livestock producers and consumers an estimated $1340 million annually, without including indirect livestock benefits such as manure and traction. Given an adoption period of 12 years, a maximum adoption rate of 30%, a discount rate of 5%, and a 30% probability of the research being successful within 10 years, the net present value of the vaccine research is estimated to be at least $288 million, with an internal rate of return of 33%, and a benefit/cost ratio of 34:1. ©     

智能化母猪饲喂控制系统设计与试验

母猪饲喂是生猪养殖中极为重要的一部分,为提高母猪产仔率,设计一种智能化母猪饲喂控制系统,该系统基于嵌入式Linux,硬件设备包括Exynos4412母板、外围控制电路集成接口板以及传感器和执行机构,负责对母猪进行信息采集、定时定量下料下水并控制装置中猪的数量。软件主要由驱动程序与应用程序协同工作保持饲喂逻辑正常运行,服务器建立在云端,应用层通过调用SQlite-API完成与后台的实时数据同步,实现精细化饲喂。试验结果表明:控制系统下料误差小于3.6%,下水误差小于3.75%;能够实时监测猪只的体温信号,重复测温误差为±0.2℃,利于饲养员对母猪健康的管理。