Assimilation Versus Accumulation of Macro- and Micronutrients in Soils: Relations to Livestock and Poultry Feeding Operations

Nutrient management is an integral part of profitable agrisystems, but in some areas of the United States, continued applications of fertilizer and manure nutrients in excess of crop requirements have led to a buildup of nutrient concentrations that are of environmental concern. Proper use of nutrients in livestock manures is becoming more critical for sustainability of concentrated animal feeding operations (CAFO) because new environmental regulations require that nutrients be properly applied and managed. Losses of nutrients, such as N and P can be reduced by refining the rations fed, increasing nutrient retention by livestock, moving manures from areas of surplus to deficiency, finding alternative uses for manure, using cropping and haying systems that remove excess nutrients, and using conservation practices, such as limited tillage, buffer strips, and cover crops to limit runoff and leaching. Whole farm nutrient balances are useful for educating producers about quantities of nutrients being managed and the flow of nutrients, but they can also be misleading because of spatial factors, such as uneven nutrient application that introduce environmental risks that may not be noted with a whole-farm nutrient balance. Manure utilization plans also need to deal with nutrients that potentially leave the field or production area in route to sensitive ecosystems.     

Nitrogen, phosphorus and potassium utilization and their cycling in a beef-forage production system

The objective of this study was to quantify nitrogen (N), phosphorus (P) and potassium (K) utilization and their cycling in a beef-forage production system. A survey was conducted at the Kyoto University experimental farm in Kyoto Prefecture, Japan, and included 9.5 ha of meadow and about 160 head of beef cattle. Forages cultivated on the meadow were ensiled and offered to breeding cows. The whole farm was regarded as a beef-forage production system. The system consisted of three components: animals, manure and soil/crop. Nutrient inputs, flows through the soil-plant-animal pathway and outputs were quantified for 2 periods for the whole farm. Nutrient utilization was evaluated by nutrient balances, utilization efficiencies (ratio of nutrient export to nutrient input) and cycling index. The average nutrient balances of N, P and K for the whole farm (kg/year/ha) were 435.7, 136.3, and 262.8, and the average nutrient utilization efficiencies were 0.08, 0.06, and 0.01, respectively. The characteristics of nutrient balances and utilization efficiencies for each component differed among the nutrients. The average cycling indices for N, P and K were 0.19, 0.17 and 0.49, respectively. This study illustrates the importance of internal nutrient cycling for improving nutrient utilization in beef production systems.     

Estimation of nitrogen and phosphorus flows in livestock production in Dianchi Lake basin,China

We assessed the nitrogen (N) and phosphorus (P) flows in intensified livestock production systems by investigating nutrient budgets and cycling in the basin of Dianchi Lake, one of the most eutrophic lakes in China. We conducted field surveys based on feed samplings and interviews of livestock farmers. The N and P in local and external feeds, animal body retentions, animal products and excretions were calculated at the individual level for dairy cattle, fattening pigs, breeding sows, broilers and laying hens. The N and P flows in the total livestock production system in the area were estimated by multiplying the individual N and P budgets by the number of animals. For the dairy and fattening pig productions, N and P supplied from local crops or by‐products accounted for large parts of the inputs. For the other livestock categories, most of the N and P inputs depended on external resources. The N and P outputs through animal manure into the cropland were 287 and 66 kg/ha/year, respectively, which were higher than the N and P inputs into the livestock production systems from the cropland. The N and P loads from manure should be reduced for the establishment of sustainable agricultural production systems.     

Nitrogen and phosphorus surpluses on Danish dairy and pig farms in relation to farm characteristics

N and P surpluses per hectare at farm level were determined on 63 private pilot farms with data from 2 to 7 years between 1997 and 2003 (a total of 245 observations). Farms were classified in the following four farm types: Conventional mixed dairy, organic mixed dairy, conventional pig farms (indoor) and conventional pig farms with outdoor sows. Import of nutrients with concentrate and fertilizer was the major input to all conventional farm types. On the organic dairy farms major input was N fixation, but also import of nutrients with concentrate and manure were important inputs. Output from the dairy farms was dominated by nutrients in milk. On pig farms nutrients in meat dominated the output, but also export of nutrients with cash crops and manure were important outputs. Farm type, year and farm within farm type significantly affected both N and P surpluses per hectare. Farm type was the major source of variation in both N and P surpluses. In the period investigated N surplus decreased by 6.5 kg N ha^− 1 yr^− 1 and P surplus decreased by 0.7 kg P ha^− 1 yr^− 1. The N and P surpluses observed on the conventional dairy farms significantly exceeded surpluses observed on the organic dairy farms. At equal number of livestock units (LU) per hectare (1.28 LU ha^− 1) the difference was 43 kg N ha^− 1 and 6 kg P ha^− 1. At equal rates of N or P in manure to fields (147 kg N ha^− 1, 29 kg P ha^− 1, respectively) the difference was 45 kg N ha^− 1 and 4 kg P ha^− 1. Conventional dairy farms and pig farms with sows indoors had equal N and P surpluses at equal rates of N or P in manure to fields. Corrected to the average year (1999.5) the estimated average N and P surpluses showed highest levels on pig farms with outdoor sows (251 kg N ha^− 1, 42 kg P ha^− 1) and lowest levels on organic dairy farms (113 kg N ha^− 1, 7 kg P ha^− 1). Surpluses on the conventional dairy farms were 175 kg N ha^− 1 and 16 kg P ha^− 1 and on the indoor pig farms they were 123 kg N ha^− 1 and 13 kg P ha^− 1. The N and P surpluses observed on Danish conventional mixed dairy farms were comparable with intensive dairy farming systems in other European countries.     

Effects of nitrogen fertilization and dried distillers grains supplementation: nitrogen use efficiency

In a 3-yr study, 135 crossbred steers (330 ± 10 kg) were used in a randomized complete block design to evaluate corn dried distillers grains plus solubles (DDGS) fed to yearling steers as a substitute for forage and N fertilizer and its effect on N use efficiency in yearling steers grazing smooth bromegrass pastures. Steers were initially stocked at 6.8 animal unit months (AUM)/ha on nonfertilized smooth bromegrass pastures (CONT), at 9.9 AUM/ha on smooth bromegrass pastures fertilized with 90 kg of N/ha (FERT), or at 9.9 AUM/ha on nonfertilized smooth bromegrass pastures with 2.3 kg (DM) of DDGS supplemented daily per steer (SUPP). Paddock was the experimental unit, with 3 replications per treatment per year for 3 yr. Paddocks were strip-grazed, and put-and-take cattle were used to maintain similar grazing pressure among treatment paddocks during the 160-d grazing season. Steers consumed less forage (P < 0.01), but total N intake for SUPP was greater (P < 0.01) per steer and per hectare than for FERT, and both were greater (P < 0.01) than for CONT. Nitrogen retention for steers in the SUPP treatment was increased (P < 0.01) by 31% compared with N retention in the CONT and FERT treatments. Nitrogen retention per hectare for SUPP was 30 and 98% greater (P < 0.01) than N retention per hectare for FERT and CONT, respectively. Nitrogen excretion per steer and per hectare were also greater (P < 0.01) for SUPP than FERT, and both were increased (P < 0.01) compared with CONT. Animal N use efficiency was similar (P = 0.29) for steers in the CONT, FERT, and SUPP treatments. However, system-based N use improved (P < 0.01) by 144% for SUPP compared with FERT. The DDGS increased N intake and N excretion in yearling steers. However, because of improvements in BW gain and increases in stocking rate of pastures, DDGS can be a useful tool to increase the efficiency of N use in smooth bromegrass grazing systems.     

Estimation of nutrient excretion factors of broiler and layer chickens in Japan

We estimated the nitrogen (N), phosphorus (P), potassium (K) and magnesium (Mg) excretion factors of broiler and layer chickens in Japan, using two approaches and the latest data available. In the top‐down approach, we determined the nutrient amounts in the feeds and those in the products (i.e. the liveweight gain, eggs), and the national nutrient excretions were determined as the difference between these amounts. We then calculated the nutrient excretion factors by dividing the national excretions by the number of animals. In the bottom‐up approach, we calculated the amounts of nutrients in the feed and product per head using productivity parameters (feed conversion ratio, etc.). The differences between these amounts were considered the nutrient excretion factors. The average nutrient excretion factors of broilers (g/day/head) estimated using the top‐down and bottom‐up approaches were: N, 1.40 and 1.87; P, 0.36, 0.50; K, 0.54, 0.77; Mg, 0.13, 0.18, respectively. The excretion factors obtained by the top‐down approach can be used to calculate the national/regional excretions. The two approaches resulted in almost the same excretion factors for layers, and the average nutrient excretion factors of layers (g/day/head) estimated were: N, 2.20; P, 0.55; K, 0.68; Mg, 0.23. The estimated excretion factors for N (only) are smaller than the reported factors.     

Implementation of Nutrient Management Planning on a Dairy Farm

Environmental policy and highly variable margins are requiring major changes on dairy farms. A case study was conducted on a commercial dairy farm over a 5-yr period to evaluate the impact of implementing methods designed to improve environmental and economic sustainability. Six Sigma (Pande et al., 2000) principles were utilized in conjunction with the Cornell University Nutrient Management Planning System (cuNMPS) to develop a system for precision farming to improve nutrient management. Critical components were the development and implementation of plans for herd nutrient management and crop, soil, and manure nutrient management. Implementation of this precision farming system resulted in increases in animal numbers (26%), milk per cow (9%), total milk sold daily (45%), and decreases in purchased feed cost (48%), feed cost per kilogram of milk sold (52%), and total manure N (17%) and P (28%) excretion. These results were attributed to improvements in forage production, quality, and storage (38% increase in proportion of diets homegrown) and precision feeding of high forage diets using the Cornell University Net Carbohydrate and Protein System (CNCPS) for diet formulation. Implementation of this approach on other farms requires management commitment and training. Training must include providing background information and tools for making continuous improvement in quality control and management and the use of root cause analysis. The adoption of the precision farming system by the case study farm management team has improved the business financially and decreased the accumulation of manure nutrients per hectare.     

Nutrient balance on Nebraska livestock confinement systems

Managing the environmental risk associated with livestock production is a significant challenge. Nitrogen and phosphorus are commonly implicated as the sources of ground and surface water quality problems associated with livestock production. The degree of imbalance between these nutrient inputs and the managed nutrient outputs for a livestock operation defines the magnitude of potential environmental risk and provides insight as to the underlying causes of these challenges. A nitrogen and phosphorus balance was constructed for 33 Nebraska confinement livestock operations. Twenty-five and 17 of these operations experienced significant nitrogen and phosphorus imbalances, respectively (50% more nutrient inputs than outputs). Nutrient inputs on many livestock operations were observed to be two to four times greater than nutrient outputs as managed crop and livestock products. Size of the livestock operation and the degree of integration of livestock with a cropping operation provided only limited explanation of the variation in nutrient balance observed among the individual operations. Management options that contribute to a more favorable nutrient balance were also identified. Management decisions related to feeding program and exporting of manure nutrients to off-farm users were observed to have a substantial impact on the nutrient imbalance. For modern livestock production systems to successfully respond to nutrient-related environmental problems, management strategies must be implemented that address the commonly experienced imbalances of nitrogen and phosphorus.     

云南湿热地区距瓣豆的铜、锌和锰营养

在云南省亚热带湿热地区为了探讨微量元素铜、锌和锰施用对引进优良豆科牧草距瓣豆生长的影响,开展铜、锌和锰的不同施量对距瓣豆干物质产量、种子产量影响的单因子完全随机区组试验.结果表明,施用铜1.2～2.4 kg/hm2和锰3. kg,/hm2的处理比对照距瓣豆干物质产量分别提高58.4%～88.4%和48.1%(P<0.05),种子产量分别提高295.5%～272.7%和80.4%(P<0.01);施铜还可提高距瓣豆氮、钙、硫、铜、锌和锰含量,显著增加单位面积距瓣豆对氮的需求量(P<0.01),其次是磷、钾、钙、硫、铜、镁、锌和锰的营养需求量(P＜0.05);施适量锰可增加距瓣豆的钙、锌和锰含量,显著增加单位面积距瓣豆的钙和锌产量(P＜0.01),其次是氮、磷、钾、镁、铜和锰的产量(P＜0.05).施用锌虽然对距瓣豆干物质产量和种子产量提高没有显著效果,但是可以提高距瓣豆的钙、锌和锰含量,显著提高单位面积距瓣豆的锌产量(P＜0.01),其次是氮、钾和锰的产量(P＞0.05),显著的降低距瓣豆对钙(P<0.01)和磷(P<0.05)的吸收量.综合分析,在施磷肥和其他元素肥的基础上,加施铜1.2 kg/hm2或锰3.9 kg/hm2,可获得高产、收益好的距瓣豆优质饲草,同时满足饲养牲畜生产的营养需要.     

放牧家畜养分消化率的测定

放牧家畜养分消化率反映牧草供给量和营养品质、家畜的健康状况以及生产性能等，是草原管理的关键指标之一。放牧家畜养分消化率的测定方法主要有直接测定和间接估测两种，直接法包括全收粪法、指示剂法、近红外光谱法（NIRS）等，间接法主要有体内或体外发酵法、牧草品质和气候等预测法。全收粪法是较精确的测定方法，然而耗时、费力，对家畜放牧行为有较大影响，难以体现牧场饲草供给的空间异质性；指示剂法根据不溶物的回收比例估测养分消化率，对家畜放牧行为干扰较小，指示剂不易收集，也不适于野性较高的放牧动物；NIRS法效率高、劳动强度低、成本小、不影响家畜，能够大尺度地估测放牧家畜的养分消化率，需要大量的实测数据完善预测模型；气候估测法快捷、省时，精确性较差，适于大时空尺度。放牧家畜的养分消化率与家畜、草地、放牧方法、温度、降水等生物因子，环境因子和社会因子密切相关，与遥感、无人机（UAV）和人工智能等结合，可以准确、快速地测定放牧家畜养分消化率，为草地生态修复与健康管理提供支撑。     

阴山北麓不同土地利用类型土壤养分特征分析与评价

采用野外实地调查采样、室内样品分析和数理统计相结合的方法,研究了阴山北麓4种不同利用类型土地的土壤养分特征,并对土壤肥力进行了综合评价。结果表明,1) 研究区土壤有机质、全氮、全磷、全钾含量分别为(25.12±6.56),(0.63±0.08),(0.76±0.10),(31.99±1.07) g/kg;速效氮、速效磷、速效钾含量分别为(39.87±9.14),(6.72±3.75),(175.83±105.45) mg/kg;pH为(7.74±0.14)。2) 土地利用方式对有机质、全氮、全磷、速效磷和速效钾的影响极显著(P<0.01),而对速效氮、全钾和pH的影响不显著(P>0.05)。3) 土壤全氮、磷、钾含量和pH值在垂直剖面上(0~25 cm自上而下)表现为无规律的波动状态,但整体上变幅不大;而速效氮、磷、钾和有机质含量整体上表现为下降趋势。4) 土壤肥力综合评价值的排序为封育草地(0.506)>放牧草地(0.417)>耕地(0.361)>弃耕地(0.357),封育草地与放牧草地的土壤肥力为中等级水平,而耕地和弃耕地的肥力为低等级水平,说明草地比耕地更有利于土壤保肥。总体而言,研究区土壤肥力水平较低,存在的主要问题是土壤中全氮和速效氮含量严重偏低。     

Considerations on the sustainability and environmental impact of intensive pastures

Intensive pastures form an important component of livestock production systems in South Africa. The sustainability and environmental impact of intensive pastures via their effects on soil properties and nutrient fluxes vary considerably depending on the systems adopted. Soil organic C and N data from various pasture systems provide evidence of a rapid decline in organic matter levels under annual pastures, particularly on coarse or medium‐textured soils. This evidence, coupled with the vulnerability of annual pastures to soil erosion during establishment, places their sustainability at risk. Soil acidification, accelerated by the use of nitrogenous fertilizers, must be counteracted by liming to ensure the sustainability of pasture systems. Phosphorus and K, both relatively immobile in pasture top soils, are not susceptible to much loss. Nitrogen, on the other hand, is susceptible to both gaseous and leaching losses. Balanced fertilization may limit N losses and soil acidification by ensuring more efficient plant utilization of this element. Research priorities indicated are the development of systems that enhance the sustainability of annual pastures, and the improvement of the efficiency of soil and fertilizer N usage in both annual and perennial intensive pastures.     

不同施磷水平对饲用柠条营养和产量的影响

在石灰性土壤上采用单因子随机区组设计进行了饲用柠条的营养与生长研究。结果显示,施用磷肥的柠条干物质产量、氮(N)磷(P)钾(K)以及钙(Ca)铁(Fe)养分吸收量和粗蛋白产量明显提高;施磷可使柠条叶的N、P、K含量增加以及茎的N、P含量增加,却减少了柠条茎叶中Ca、Fe含量以及茎中K含量。不同施磷水平与干物质产量以及粗蛋白产量之间存在相关性,相关关系均达到显著水平(P<0.05)。施磷可以调节饲喂柠条的Ca/P值,达到家畜日粮的Ca/P标准。结果还表明,180kg/hm²P₂O₅是最佳的磷施用量,干物质产量和粗蛋白产量在所有处理中最高,与不施磷对照相比,干物质产量定植当年提高76.5%,第2年提高73.9%;粗蛋白产量当年提高83.97%,定植第2年提高91.05%。同时,该磷用量下柠条的Ca/P较理想。另外,结果分析还表明,柠条单纯作为饲料资源时,建议在养分管理上要隔年施1次磷肥,用量以P₂O₅180kg/hm²为准,以满足柠条生长的营养需求和维持柠条的高产稳产。     

Development and evaluation of a model for prediction of fecal and urinary nitrogen excretions in cattle

The reduction of nitrogen (N) excretion in animal production is crucial in intensive farming systems particularly in the developed countries. In this study, a model to predict N excretion in cattle was developed based on existing feeding standards and evaluated using independent N balance experiments for Holstein steers and lactating cows and Japanese Black (JB) steers. Although model predictions for fecal and urinary N excretions appeared to be close to observed values in plot figures, statistical analysis showed that the model tended to over-predict both fecal and urinary N excretions, especially in Holstein lactating cows. This was because body weight changes of cows during lactation period were not considered in the model due to the lack of information (i.e., body weight gain or loss) available in the experimental data for evaluation. There were large mean bias and small line bias for urinary N prediction, but reverse results were obtained for fecal N prediction. The largest mean square prediction errors for both N excretions were due to random variation in all cases. When all data were pooled (combined), the accuracy for predictions for fecal N excretion was considerably high (r² = 0.94), indicating that the model may predict fecal N excretion beyond breeds, sexes and physiological states (growing and lactating). More information and accumulated data will be required to predict urinary N excretion under a wide range of genotype and environmental situation.     

Technical note: stocking equivalents and stocking rate-gain relationships for steers and cow-calf pairs grazing oversown bermuda grass.

Grazing experiments may use steers or cow-calf pairs for measuring animal performance on pasture treatments, but the validity of extrapolation between these classes of cattle has not been verified. A grazing study was conducted in the spring and summer of both 1988 and 1989 to determine stocking equivalents and stocking rate-weight gain relationships for steers and cow-calf pairs grazing Coastal bermuda grass (Cynodon dactylon [L.] pers.) oversown with rye (Secale cereale L.) and ryegrass (Lolium multiflorum Lam.). Average daily gain and stocking rate (SR; 3.2, 4.2, 6.2, and 7.4 animals per hectare for steers and 1.7, 2.5, 3.7, and 4.9 pairs per hectare for cow-calf pairs) were both adjusted so that comparisons could be made on an equal BW basis. Disk meter height readings were used as measurements of forage accessibility. Disk meter height responses to SR did not differ (P greater than .10) between steer and cow-calf paddocks. There was a linear (P less than .001) decrease in ADG as SR increased, but this decline was steeper (P less than .001) for steers than for cows or suckling calves. Steers tended to be more productive than calves at low SR but less productive at high SR. Disk meter heights for the range of SR used in the study did not differ (P greater than .10) for steers and cow-calf pairs at equivalent BW per hectare. Our study suggests that live BW is a reasonable basis for determining forage requirements of steers and cow-calf pairs under grazing conditions, but extrapolation of production between classes of livestock will not be reliable.     

塔克拉玛干沙漠南缘荒漠绿洲过渡带不同土地利用影响下优势植物化学计量特征

荒漠绿洲过渡带天然植被对于绿洲生态环境的维护具有非常重要的意义。土地利用等绿洲化的人类活动如何影响天然植被对于评估过渡带的植被结构和功能非常重要。生态化学计量学在限制性营养判断和评估生态系统稳定性上得到了广泛利用。以塔克拉玛干沙漠南缘典型植物多枝柽柳、疏叶骆驼刺和花花柴为研究对象,研究不同土地利用方式和强度对植物碳(C)、氮(N)、磷(P)、C∶N、C∶P和N∶P的影响。研究表明,3种植物的C、N、P、C∶N、C∶P和N∶P平均值分别为385.94 mg·g^-1、13.62 mg·g^-1、1.49 mg·g^-1、30.33、294.01和9.69。与干旱区以及全球其他群落类型相比,植物C和P处于中间水平,而N则普遍低于其他区域。土壤的利用方式、强度以及二者的交互作用能够显著影响大部分指标。过渡带不同利用方式外围荒漠样点C、N、P及其比值差异较大,土地利用后也具有较大的差异。土地利用后,3种植物的总C呈下降趋势,而N和P整体呈增加趋势,利用程度越高,增加越明显,但也受物种差异的影响。土壤与植物元素含量的相关关系在物种间具差异性,土壤与柽柳和花花柴两种植物营养之间相关性非常低。3种植物的N和P之间具有显著相关性。塔克拉玛干沙漠南缘区域植物普遍缺少N素,土地利用在一定程度上缓解这种N素缺乏。随着荒漠绿洲过渡带利用强度的变化,预计过渡带植被的化学计量将发生不同的改变。     

An approach to nutrient management on dairy farms

In the European Union, groundwater should contain less than 50 mg of nitrate/L. Individual countries have developed alternative strategies for phosphorus (P). In The Netherlands, regulations based on P limited the amount of manure applied per hectare. A more balanced P supply to the land has been achieved by transport of manure from surplus to deficit regions. Costs of processing of manure to pellets appeared to be (too) high. In animal production experiments, lowering the P content of concentrates and mineral supplements reduced P losses without an adverse effect on production. In addition to the European guideline for nitrate, ammonia volatilization should be reduced by 50 to 70%. Management practices for reducing nitrogen (N) losses were studied with a farm model, developed at PR. A combination of a more efficient use of fertilizer N, restricted grazing, and a more balanced diet, and, to a lesser extent, higher milk production per cow resulted in considerable reductions in nitrate leaching. The application of slurry by injection diminishes the ammonia volatilization at farm level by almost 50%. This technique has become obligatory, and is only allowed during the growing season. Other techniques, like low emission housing and covering of slurry storage have relatively high costs. Starting in 1998, farmers have to keep a record of nutrients on a balance sheet. A tax will be imposed on surpluses of N and P. This new instrument replaces the regulations based on P. To further improve efficiency of use of N and P, farmers have the nutrient balance sheet available as an integrated management tool. Urea content in bulk milk has been introduced as a new indicator for the utilization of N in the diet. Also, fertilizer applications are improved. Furthermore, an experimental farm was set up to integrate all available expertise and analyze the resulting nutrient flows and farm performance.     

Pasture intensification in beef cattle production can affect methane emission intensity

Increasing greenhouse gas (GHG) emissions from anthropogenic activities have contributed to global warming and consequently to climate change. Among all sources of emissions, the agricultural sector accounts for just under a quarter, mainly because of the intensification of food production systems necessary to supply the growing demand of the population. As ruminal fermentation is the largest source of methane emission in the livestock industry, emission by cattle has become the focus of studies. The aim of this study was to evaluate enteric methane emission and emission intensities of Nellore cattle at different ages submitted to levels of intensification of the grazing system. Twenty-four animals per cycle (age of 21.8 and 13.1 mo in cycles 1 and 2, respectively) were randomly distributed across different grazing systems: irrigated pasture with a high stocking rate (IHS), dryland pasture with a high stocking rate (DHS), recovering dryland pasture with a moderate stocking rate (DMS), and degraded pasture with a low stocking rate (DP). Methane emission was measured using the sulfur hexafluoride technique in each season of the cycle. Intensive systems provided higher yields of good-quality forage as well as superior animal performance when compared with DP. Methane yields were different between seasons and cycles. Methane emissions per average daily weight gain and dry matter digestible intake were different between treatments. Differences in the results were observed when they were analyzed per hectare, with the highest gain yield (P = 0.0134), stocking rate, weight gain, carcass production, and total methane emission (P < 0.0001) being found for the intensive systems. There were no differences in emissions per weight gain or carcass production between production systems, while a difference was observed between cycles (P = 0.0189 and P = 0.0255, respectively), resulting in lower emission intensities for younger animals. We conclude that more intensive systems resulted in a higher kilograms production of carcass per hectare; however, animals at 19 mo of age raised in the IHS and DMS systems had a lower emission intensity in kilogram of CO₂-eq. per kilogram of carcass. Moderate intensification (DMS) using animals at about 19 mo of age might be an effective strategy to mitigate GHG emissions from Brazilian tropical pastures. Further studies are needed to understand the relationship between increasing productivity and decreasing environmental impacts, especially methane emission from ruminants.     

Effect of subsidy regimes on economic values of functional traits in beef cattle breeding

We investigated the impact of five monetary subsidy regimes on economic values of traits in a cow–calf pasture production system with surplus calves fed for slaughter. The following regimes were analysed: (1) maximum prices for slaughter animals actually received in the Czech Republic during 2004, with no subsidies of any kind; (2) prices as in (1), with subsidies awarded per hectare of permanent grassland and per calf born; (3) prices as in (1), with subsidies awarded per hectare of agricultural land, per hectare of pasture and meadow, per beef cow in a forage system and per livestock unit; (4) prices as in (1), with subsidies awarded per hectare of agricultural land; (5) no subsidies, but prices received for slaughter animals that covered production costs and resulted in 1% profitability. The modelled farm showed negative profit under real price conditions with no subsidies (regime 1), which led to an underestimation of economic values for functional traits. The same results were obtained in regimes in which subsidies did not depend on the number of animals (3) or on meat production from the enterprise (4). Economic values of production traits (growth and carcass traits) did not vary among subsidy regimes. To determine optimum economic values for functional traits in beef cattle, we advocate using the method applied in subsidy regime 5, no subsidies but prices for slaughter animals that cover production cost and a small profit.