放牧对乳成分和乳产品感官品质影响的研究进展

集约化养殖提高了牧场奶牛的生产效率,其生产过程中动物福利、环境保护以及产品质量等议题也逐渐引起消费者的关注。放牧养殖将户外放牧和牧草采食作为养殖模式的评判标准,其产品正逐渐受到欧美等发达国家消费者的青睐。饲料中的优质牧草是影响乳成分及其乳制品品质的主要因素之一,牧草中较高的纤维含量维持了瘤胃健康,较高的不饱和脂肪酸提高了乳脂中不饱和脂肪酸的比例,丰富的可降解蛋白提供了乳蛋白的合成原料,并且牧草中脂肪酸、氨基酸、碳水化合物和其他营养物质在奶牛体内的代谢影响了牛奶以及乳制品的感官品质。作者重点关注一些国家放牧养殖的实际状况和标准要求,及其与有机养殖的差异对比,并分析放牧养殖和全混合日粮喂养条件下饲料成分差异对奶牛瘤胃代谢的影响,以及由此造成的牛奶脂肪、蛋白成分和感官指标等方面的差异。     

Advance on Effects of Grass Feeding on Milk Composition and Sensory Quality of Dairy Products

With the development of intensive cultivation in dairy cows,the production efficiency of dairy farms has been improved.However,issues such as animal welfare,environmental protection and product quality of dairy farm have received more attention.As judging criteria in the pattern,outdoor grazing and grass intake necessary in grass-fed farming,and its products are gradually being favored by consumers in developed countries,such as Europe and the United States.The effect of grass-fed on milk and dairy products mainly depend on the quality of forage grass.The high fiber content in forage grass maintains rumen health,high unsaturated fatty acids increase the proportion of unsaturated fatty acids in milk fat,and rich degradable proteins promote milk protein synthesis.The metabolism of fatty acids,amino acids,carbohydrates and other nutrients from forage in dairy cows may affect the sensory quality of milk and dairy products.This review focused on the actual situation and standard requirements of grass-fed in some countries,and their differences compared with organic farming,and analyzed the effects of feed composition differences on rumen metabolism of dairy cows under grazing farming and total mixed diet feeding conditions,as well as resulting differences in milk fat,protein and sensory indicators.     

影响反刍动物氮素利用效率和排放的营养实践

涉及奶牛生产系统和粪肥应用的总氨氮排放参数是影响农业源氨氮排放的最敏感的参数,如何通过精细饲养来提高奶牛的氮素泌乳转化效率,降低奶牛生产系统的氮素排放,对于缓解奶牛生产系统面临的经济与环保双重压力具有重要意义。本文从饲粮的氮素水平、碳水化合物类型、氨基酸补饲、饲料添加剂、饲粮精粗比以及新型饲料原料等方面对影响反刍动物氮素排放的研究进行了综述,同时介绍了康奈尔净碳水化合物-蛋白质体系(CNCPS)模型及其改进对奶牛场氮排放估测的影响以及尿素转运蛋白对反刍动物氮素代谢的影响。     

Impact of feeding pattern and feed purchase on area- and cow-related dairy performance of organic farms

Livestock production and ruminants in particular are an integral part of the organic mixed farming concept. In this paper, the feeding patterns of 26 organic dairy farms in two different regions in Germany are analysed, with particular emphasis on the amount and proportion of concentrates and purchased feed related to the dairy performance expressed per cow and hectare. Calculated on an energy basis (MJ NEL), the annual average milk yield of 6737 kg cow^− 1 is derived from roughage (74%), concentrates and cobs (23%), and commercial processing by-products (e.g., spent grains) (3%). Per cow and year, 937 kg dry matter (DM) (range: 0–2724 kg) of concentrates are fed with an intensity of 135 g kg^− 1 milk (range: 0–378 g kg^− 1). Approximately 65% of the concentrates and commercial processing by-products are purchased. The area-related milk yield is almost 7000 kg ha^− 1. For fodder production, 0.96 ha per cow is needed, of which 0.85 ha is farm land. The equivalent production area for purchased fodder is 0.11 ha. In the analysed region in northwestern Germany, most correlations between milk yield and analysed feeding parameters are close and significant. This is in contrast to the region in the south, where the variability of amount and proportion of the different feed types is predominantly independent of the milk yield. Intensification of dairy production to increase milk performance using a higher proportion of concentrates and purchased feed at some of the analysed farms needs to be carefully assessed according to the organic farming profile.     

Evolution of farm management, nitrogen efficiency and economic performance on Dutch dairy farms reducing external inputs

The implementation of the statutory Mineral Accounting System (MINAS) in the Netherlands in the period 1998–2003 required large reductions in nutrient inputs of dairy farms. Patterns in farm management adjustments throughout 6 years and their effectiveness in terms of nitrogen use efficiency (NUE) and economic performance were evaluated for 45 commercial farms participating in a regional nutrient management project.

Six groups of farms were identified that differed in initial NUE and the change therein. Three groups of farms that were able to rapidly reduce fertilizer N input and establish a consistent farm management strategy were most successful in improving NUE. These farms had a higher gross margin per 100 kg milk than farms without a consistent strategy. The three effective strategies were primarily characterized by (i) continuous, gradual adjustment of the integrated farm management combined with a slight reduction in milk production per ha (re-balancing) versus increasing productivity per animal, thereby reducing maintenance N requirements, while (ii) maintaining or (iii) increasing the production intensity per ha. It was concluded that different approaches to improve NUE can be successful, also in economic terms, although a direct relationship between NUE and gross margin was not observed. The probably implicit choice for adoption of a strategy may be governed by farm endowment and the farmer's skills and objectives.     

奶牛场温室气体排放与减排措施

奶牛养殖在产能提升的同时也排放了大量温室气体。本文梳理了奶牛养殖场温室气体排放的重点环节,主要分为奶牛养殖活动温室气体排放以及牛场日常运行耗能两个方面;结合奶牛养殖肠道发酵和粪污管理的温室气体核算方法,归类整理了主要的减排措施,包括进行提高饲料质量和转化效率、粪污高效管理、清洁能源替代等方式,助力奶牛养殖实现低碳乃至零碳排放。     

高寒地区秋、冬季荷斯坦奶牛补饲优质饲料对采食量、泌乳性能和乳房炎发病率的影响

[目的]旨在研究高寒地区荷斯坦奶牛优化补饲方案的推广价值。[方法]实验选取A、B牧场无临床型乳房炎健康泌乳牛为研究对象,将两座实验牧场奶牛,分别各自分为实验组和对照组。实验组饲喂优质补饲日粮,对照组饲喂传统日粮,实验牛只每天放牧5 h。实验期为60 d,10 d为预饲期,50 d为实验期。[结果]A、B牧场实验组补饲的日粮干物质采食量分别为15.77、16.11 kg/d,明显高于对照组（14.02、14.47 kg/d）。A牧场实验组单产为16.89 kg/d,对照组单产为12.25 kg/d,差异显著（P〈0.05）;B牧场实验组单产为17.22 kg/d,对照组单产为13.21 kg/d,同样差异显著（P〈0.05）;同时A牧场与B牧场实验组的单产在与2014同期相比时同样差异显著（P〈0.05）。A牧场每千克奶饲料成本降低0.26元,与对照组相比差异显著（P〈0.05）,B牧场降低0.13元。A牧场实验组的牛奶乳脂率和乳蛋白含量明显高于对照组,分别为3.95%和3.28%,和2014年同期相比分别增长了0.29%和0.22%;B牧场实验组牛奶乳脂率和乳蛋白含量虽然低于对照组,但也达到了4.08%和3.15%。A牧场实验组牛奶体细胞数（39.14万个/m L）比对照组体细胞数（60.54万个/m L）低21.40万个/m L。临床型乳房炎患病牛的比例,实验组低于对照组近2.67%。[结论]高寒地区荷斯坦奶牛可实行优化补饲方案,且能够提高企业和养殖户的经济效益,具有较好的推广价值。     

Participatory rural appraisal in smallholder dairy systems in Tunisia

Participatory Rural Appraisal (PRA) was carried out by a multidisciplinary team on a total of 60 smallholder dairy farms in three different geographical areas of Tunisia. Farms with less than three cows were excluded. Those participating had between three and 10 cows. Average milk production ranged between 8 and 32 litres per cow per day. 70% or over of milk produced was sold off the farms. Average inter-calving intervals — measured from month of calving only — ranged from 12.9 months to 19. Age at first calving varied from two to nearly three years. Most work was done by the families. PRA revealed that the farmers in all three regions perceived unbalanced nutrition, which included availability of forages, to be the most important constraint, followed by poor reproductive efficiency. Reseeding with new species was instituted for grazing and hay. Farmers from the different regions were taken on exchange visits to see how these approaches worked. Training in reproductive management and milking hygiene was introduced. Seasonal ration formulation depending on local forage analysis was instituted. Two farms are participating in a programme of evaluation of olive oil extraction by-product as a ruminant feed. Partial budget analysis of these interventions will be carried out.     

An economic comparison of typical dairy farming systems in South Africa, Morocco, Uganda and Cameroon

Population growth, urbanisation and increased per capita milk consumption are main reasons for recent increasing milk demand in Africa. Due to globalisation, it is important to know how competitive various production systems are, especially as most governments promote local production and disfavour dairy imports. The TIPI-CAL (Technology Impact, Policy Impact Calculations model) was used to analyse and compare costs and returns of predominant dairy farming systems in South Africa, Morocco, Uganda and Cameroon. Results show that, as farms grew larger in size, family resources (especially land and labour) became insufficient and there was need for their acquisition from external sources. Though extensive dairy farming systems had the lowest cost of milk production (<20 US-$ per 100 kg milk), their input productivities and milk yields were lower, leading to very low net cash returns from dairying. Large intensive farms in South Africa had relatively low costs (<30 US-$ per 100 kg milk) and a high Return on Investment (ROI) due to a higher efficiency of input utilisation. It was concluded that, intensification of dairy farming and simultaneously increasing the scale of production will greatly increase productivity of farm inputs, thus recommended for development of the dairy sector in African countries.     

华北地区规模化奶牛场用水及粪污处理情况调查报告

本次调研共收集了华北地区99家奶牛场的用水及粪污处理情况数据进行了分析总结。结果表明,①85.9%的牛场以深井水作为水源,其中61.2%的牛场对用水进行消毒处理,43.5%的牛场安装有水表并记录用水情况。②在牛场用水中,牛的饮水量所占比例最高,达60%以上;其次为挤奶厅用水,约占20%。③夏季牛场头均饮水量、挤奶厅用水量、喷淋用水量均显著高于春秋冬季(P<0.05),夏季的头均总用水量比春秋冬季增加了33%(P<0.01)。随着牛场存栏量的增大,奶牛头均总用水量显著减少(P<0.05)。④年产奶量较高的牛场每产1kg牛奶饮水量、挤奶厅用水量显著降低(P<0.01),致使每千克产奶量的总用水量减少52%(P<0.01),用水效率提高。⑤随着养殖规模的增大,牛场雨污分离设施与干湿分离设施配备率分别显著增至62%、72%(P<0.05,P<0.01)。由此可得,存栏量越大、年产奶量越高,牛场每产1kg牛奶用水量越低,用水效率越高,而且配备的雨污分离设施、干湿分离设施比例越高,这些均有利于减少单位产奶量的粪污产生量及其处理压力。     

Supporting the extensive dairy sheep smallholders of the semi-arid region of Crete through technical intervention

The objective of this field study was to depict the extensive system of dairy sheep farming in the semi-arid environment of the island of Crete and to assess the potential margins of improvement through technical intervention. Forty-three family-run farms keeping a total of 13 870 sheep were surveyed in seven representative areas of the island. Several parameters were dealt with, concerning socio-economy, flock management and productivity. Study areas differed widely regarding feeds supplied per sheep, land cultivated for feeds, grazing land utilized and housing space. A range of parameters were recorded on flock size and their production characteristics such as births, fertility and number of lambs weaned. Milk yield and parameters associated with milk quality, such as somatic cell counts and total microbial flora, were also recorded. Technical intervention was directed towards removal of non-productive animals, programming of matings, balancing of diets, management of grazing lands and health care. Ewe fertility and numbers of lambs weaned per ewe, as well as harvested milk and milk quality (based on somatic cell counts and microbial load of milk) were also significantly improved. Information derived from this study stresses the important role of extension services to small farm sustainability and contributes to our knowledge of the dairy sheep farming systems in countries around the Mediterranean and elsewhere.     

Impact of management interventions on smallholder dairy farms of the western highlands of cameroon

A study was carried out to evaluate the impact of interventions to solve constraints in smallholder dairy farms of the Western Highlands of Cameroon. The interventions consisted of improved breeding through introduction of artificial insemination, better feed supplementation, farmers training in milk processing and better veterinary services. Results show that there was a decrease in average monthly expenditures of 18% relative to the month before interventions started. Much of the expenditures were related to feed (38% of all costs). There was an overall increase in farm income. Close to 2/3 of the income were derived from milk products from home processed milk and culled animals. Only 7% income came from milk sold to the processing plant. The partial budget shows that before interventions, farmers lost $4.5/cow/month but gained $38/cow/month because of the interventions. The return was 2.32 and included opportunity income for milk home consumed and shared. When this opportunity income was ignored, the return stood at 1.93. The positive impact of interventions led to poverty alleviation and some farmers acquired more cows. A spill over effect is that more crop farmers are willing to be engaged at least partially in dairy farming. It will be good if many more farmers could benefit from these interventions.     

The economic margins of activities of a bovine practitioner on dairy farms

Because of lower margins and market liberalisation veterinarians and farmers are increasingly negotiating rates. Therefore, the margins of veterinarians are under pressure. In addition, the sales if drugs, performance of operations or giving of advice are more and more separated. These developments give veterinarians uncertainty about the profitability of their activities for dairy farmers. Not much is known about margins on veterinary activities on dairy farms. Moreover, it is interesting to see how much margins of the bovine practitioner differ between veterinary practises and dairy farms. In this study, invoices for bovine activities of 14 veterinary practises were combined with milk production registration data of the dairy farms of these practices. This way, the gross margin per bovine practitioner could be studied for the different veterinary practise. Moreover the relation between gross margin and specification of the veterinary practise could be studied. Finally, the gross margin per dairy farm and the factors that influenced this gross margin were studied. The most important result was the observation that the gross margin per bovine practitioner was dependent on the number of dairy farms per practitioner, the margin on drugs and the region of the veterinary practise. The size of the veterinary practise, the share of the dairy farming within the practise and the source of the gross margin (drugs, time or operations) did not influence the gross margin. Variables that explained the gross margin per dairy farm were, amongst others, the number of dairy cows, the milk production level of the farms and participation in PIR-DAP (a system to support the veterinarians herd health and management program). There is no relation of gross margin per dairy farm and the veterinary practise or region.     

A beef herd model for simulating feed intake, animal performance, and manure excretion in farm systems

A beef herd submodel was created for integration with other farm components to form a whole-farm model capable of simulating a wide range of beef production systems. This herd submodel determined the best available feed or feed mix to meet the fiber, energy, and protein requirements for each of up to six animal groups on the farm. The groups comprised any combination of cows, nursing calves, young heifers, yearling heifers, stockers, and finishing cattle. Protein, energy, and mineral requirements were determined for each group using the Cornell Net Carbohydrate and Protein System, Level 1. Diets were formulated to meet these requirements with available feeds, and the resulting feed intake, growth, and manure DM and nutrient (N, P, and K) excretions were predicted. Required feed characteristics included CP, ruminally degradable protein, acid detergent insoluble protein, NDF, P, and K concentrations. Feed intake was predicted by considering energy intake, potentially limited by fill, and exceeding a minimum roughage requirement. Fill and roughage limits were functions of feed NDF concentrations adjusted to consider particle size distribution and the relative rate of ruminal digestibility or the physical effectiveness of the fiber. The herd submodel was verified to predict feed intakes, nutrient requirements, diets, and manure excretions similar to those recommended or measured for beef animals. Incorporation of the beef herd submodel with other farm components, including crop growth (alfalfa, grass, corn, small grain, and soybean), harvest, storage, feeding, grazing, and manure handling, provided the Integrated Farm System Model. This comprehensive farm-simulation model is a useful research and teaching tool for evaluating and comparing the long-term performance, economics, and environmental impact of beef, dairy, and crop production systems.     

中美奶牛养殖成本收益比较分析

由于我国奶业转型发展仍存在原料奶成本高、乳制品竞争力弱等问题,奶业提质增效一直是政府和社会广泛关注的问题。本文利用2018—2021年奶牛养殖调研数据以及官方统计数据,比较分析了中美两国奶牛养殖成本构成以及成本收益情况。结果表明,我国奶牛养殖公斤奶成本明显高于美国,但差距不断缩小;饲料成本在两国奶牛养殖成本比重差异较大,中国平均占比为67.1%,美国为47.4%;中国在机械化和智能化设备方面投入明显少于美国,但美国奶牛养殖收益明显少于中国,且近几年一直处于亏损状态。大规模养殖场在成本和收益方面具有明显优势,大规模养殖场能更大程度发挥机械和智能化设备投入带来的规模经济。我国应加快发展优质饲草料产业,从根本上降低奶牛养殖成本、提高养殖收益;稳步提升奶业发展科技水平,增加机械和智能化设备投入,促进奶业现代化高质量发展。     

Organic dairy farming in Norway under the 100% organically produced feed requirement

The derogation to use a percentage of cheaper non-organic feeds in organic livestock diets for herbivores expired from January 2008. (In Norway, a maximum of 15% conventional feedstuffs per year was allowed until 24 August 2005, 5% in the interim.) This study aimed to assess changes in resource use and financial impacts for organic dairy herds of the 100% organic feeding rule (compared with 85% organic feeds) using a two-stage stochastic programming modelling framework. In this study, the objective function was to maximise expected net income. Two organic dairy farms in the lowlands of southern Norway, both having a milk quota of 100,000 l but with varying farmland availability (37 ha vs. 20 ha), were examined. Furthermore, situations with and without possibilities to buy organic silage were studied. Milk production per cow was highest on the farm with the most strict land constraint. For farmers that fully utilise the non-organic feed allowance, the more expensive organic feeds determine the marginal feed cost. Hence, a removal of the non-organic feed allowance will not influence optimal farm practice (provided that marginal milk production is still profitable). A switch from conventional to organic concentrates as the only adjustment was found on the 37 ha farm and also on the 20 ha farm if there was no possibility to buy some organic silage. On the 20 ha farm with possibilities to buy organic silage, it turned out to be unprofitable to keep all the cows. Fewer cows resulted in several other changes in the model solution such as a lower milk yield per cow, less milk produced in total and more work off-farm. The financial gain from carrying out the optimal management changes was, however, very small. In all cases studied, the introduction of 100% organic feeds resulted in an economic loss of NOK 19,200–23,600 (or 7–12% of the expected net income with 85% organic feeds). The economic losses were due to the price premium of organic concentrates.     

Effects of ear corn silage supplementation on milk production and milk fatty acid profiles in grazing dairy farms

This study investigated the effects of substituting ear corn silage (ECS) for commercial formula feed on milk production and milk fatty acid profiles in grazing dairy farms during the summer season. A field survey was conducted on five grazing dairy farms in every summer month of 2017, 2018, and 2019. Three of the five farms substituted fresh ECS for the commercial formula feed at a ratio of 2:1 from July of each year (ECS farms). Other farms maintained the same feeding management as before (non‐ECS farms). An interview survey was conducted on each farm to calculate feed intake and milk yield per cow. Feed and milk samples were collected in each survey. Milk compositions and milk fatty acid profiles were determined. The substitution of ECS for the commercial formula feed did not affect milk yield or milk composition, but ECS farms maintained low levels of milk urea compared with non‐ECS farms (p < .01). The ECS substitution also influenced some of the milk fatty acid proportions; C16:0 and C16:1 increased, and trans‐11 C18:1, cis‐9,trans‐11 C18:2, and the sum of polyunsaturated fatty acids decreased, while these fatty acid proportions were maintained in non‐ECS farms throughout the summer season (p < .05).     

Performance and limitation of two dairy production systems in the North western Ethiopian highlands

In order to characterise the dairy production systems as well as the productive and reproductive performance of dairy cows in the study area, a total of 256 and 54 dairy farms were used for survey and monitoring data collection, respectively. Based on breed, land size, feed and market accessibility, two major dairy production systems were identified: a rather specialized, urban, and a peri-urban dairy production system. Urban farmers owned larger herds but farmed less land, and sold a greater proportion of liquid milk than peri-urban farmers, who processed more milk. Purchased feed played a more important role for the feed supply of urban than peri-urban farms. Significant breed effects were found for productive and reproductive performance traits. It is concluded that improved breeding and health management, genetic improvement of local breeds and supplementation of poor quality feed resources are the key factors for enhancing productivity of dairy cows and thereby increasing family income from milk production.     

Phosphorus Intake and Excretion on South Carolina Dairy Farms

The objective of this study was to survey dairy farmers to determine P levels in feed and manure. Feed and manure samples were collected from 19 Holstein, six Jersey, and two Guernsey farms in South Carolina. Samples from the Jersey and Guernsey herds were pooled. Samples were dried and analyzed for N and P. Amounts of all feeds were recorded; then, nutrient intake was determined. Dairy Herd Improvement records were used to determine the milk yield and fat content and, subsequently, the P requirement. Nineteen of 27 herds (70%) were fed more P than required according to nutrient requirements established by the NRC. The average P intake was 94.9 g (0.48% of diet DM) compared with the average requirement of 78.3 g (0.41% of diet DM). There were correlations between dietary and fecal P (R² = 0.46) and between CP and P intake (R² = 0.62). There was not a significant correlation between excess P intake and milk yield. In summary, many dairy producers overfeed P. Feeding dietary P at recommended levels will optimize milk yield and reduce P excretion on dairy farms.     

Energy intake and requirement of dairy cows during the whole year

It is argued that in view of the many new methods in dairy farming an economic model of the dairy farm should be available to improve advisory work. Some quantitative data concerning the dairy cow needed for such a model are given. They deal with a net energy feeding value of grass, hay, silage, artificially dried grass and concentrates estimated with a feed evaluation system based on results obtained with lactating cows. Also data on the requirements for net energy and for long forage dry matter are given, again obtained with such cows. Finally information is given on voluntary intake of forage dry matter at pasture, from fresh grass fed indoors, from various preserved forages including forage pellets, as influenced by milk yield and condition of the cow and by kind of forage and level of concentrates fed. Special attention has been paid to the precision of the information. These data are used to predict both the maximal and minimal amounts of long forage which can be fed in the stall period without loss of production, and the additional quantities of concentrates needed. For the grazing cow the problem of the adjustment of voluntary intake of grass to milk yield and amount of concentrates fed is studied. It is concluded that the information is sufficient to develop an economic model of a dairy farm. For its development grassland research should supply data on pasture yield in terms of digestible organic matter when the forage is fed to sheep at the maintenance level, and the economists should add data on costs of food and labour.