Th.V. Vellinga

The impact of grassland ploughing on CO2 and N2O emissions in the Netherlands

The contribution of ploughing permanent grassland and leys to emissions of N2O and CO2 is not yet well known. In this paper, the contribution of ploughing permanent grassland and leys, including grassland renovation, to CO2 and N2O emissions and mitigation options are explored. Land use changes in the Netherlands during 1970–2020 are used as a case study. Three grassland management operations are defined: (i) conversion of permanent grassland to arable land and leys; (ii) rotations of leys with arable crops or bulbs; and (iii) grassland renovation. The Introductory Carbon Balance Model (ICBM) is modified to calculate C and N accumulation and release. Model calibration is based on ICBM parameters, soil organic N data and C to N ratios. IPCC emission factors are used to estimate N2O-emissions. The model is validated with data from the Rothamsted Park Grass experiments. Conversion of permanent grassland to arable land, a ley arable rotation of 3 years ley and 3 years arable crops, and a ley bulb rotation of 6 years ley and one year bulbs, result in calculated N2O and CO2 emissions totalling 250, 150 and 30 ton CO2-equivalents ha–1, respectively. Most of this comes from CO2. Emissions are very high directly after ploughing and decrease slowly over a period of more than 50 years. N2O emissions in 3/3 ley arable rotation and 6/1 ley bulb rotation are 2.1 and 11.0 ton CO2-equivalents ha–1 year–1, respectively. From each grassland renovation, N2O emissions amount to 1.8 to 5.5 ton CO2-equivalents ha–1. The calculated total annual emissions caused by ploughing in the Netherlands range from 0.5 to 0.65 Mton CO2-equivalents year–1. Grassland renovation in spring offers realistic opportunities to lower the N2O emissions. Developing appropriate combinations of ley, arable crops and bulbs, will reduce the need for conversion of permanent pasture. It will also decrease the rotational losses, due to a decreased proportion of leys in rotations. Also spatial policies are effective in reducing emissions of CO2 and N2O. Grassland ploughing contributes significantly to N2O and CO2 emissions. The conclusion can be drawn that total N2O emissions are underestimated, because emissions from grassland ploughing are not taken into account. Specific emission factors and the development of mitigation options are required to account for the emissions and to realise a reduction of emissions due to the changes in grassland ploughing.

Strategies to mitigate nitrous oxide emissions from herbivore production systems

Herbivores are a significant source of nitrous oxide (N(2)O) emissions. They account for a large share of manure-related N(2)O emissions, as well as soil-related N(2)O emissions through the use of grazing land, and land for feed and forage production. It is widely acknowledged that mitigation measures are necessary to avoid an increase in N(2)O emissions while meeting the growing global food demand. The production and emissions of N(2)O are closely linked to the efficiency of nitrogen (N) transfer between the major components of a livestock system, that is, animal, manure, soil and crop. Therefore, mitigation options in this paper have been structured along these N pathways. Mitigation technologies involving diet-based intervention include lowering the CP content or increasing the condensed tannin content of the diet. Animal-related mitigation options also include breeding for improved N conversion and high animal productivity. The main soil-based mitigation measures include efficient use of fertilizer and manure, including the use of nitrification inhibitors. In pasture-based systems with animal housing facilities, reducing grazing time is an effective option to reduce N(2)O losses. Crop-based options comprise breeding efforts for increased N-use efficiency and the use of pastures with N(2)-fixing clover. It is important to recognize that all N(2)O mitigation options affect the N and carbon cycles of livestock systems. Therefore, care should be taken that reductions in N(2)O emissions are not offset by unwanted increases in ammonia, methane or carbon dioxide emissions. Despite the abundant availability of mitigation options, implementation in practice is still lagging. Actual implementation will only follow after increased awareness among farmers and greenhouse gases targeted policies. So far, reductions in N(2)O emissions that have been achieved are mostly a positive side effect of other N-targeted policies.

Environmental impacts of innovative dairy farming systems aiming at improved internal nutrient cycling: A multi-scale assessment.

Several dairy farms in the Netherlands aim at reducing environmental impacts by improving the internal nutrient cycle (INC) on their farm by optimizing the use of available on-farm resources. This study evaluates the environmental performance of selected INC farms in the Northern Friesian Woodlands in comparison to regular benchmark farms using a Life Cycle Assessment. Regular farms were selected on the basis of comparability in terms of milk production per farm and per hectare, soil type and drainage conditions. In addition, the environmental impacts of INC farming at landscape level were evaluated with the integrated modelling system INITIATOR, using spatially explicit input data on animal numbers, land use, agricultural management, meteorology and soil, assuming that all farms practised the principle of INC farming. Impact categories used at both farm and landscape levels were global warming potential, acidification potential and eutrophication potential. Additional farm level indicators were land occupation and non-renewable energy use, and furthermore all farm level indicators were also expressed per kg fat and protein corrected milk. Results showed that both on-farm and off-farm non-renewable energy use was significantly lower at INC farms as compared with regular farms. Although nearly all other environmental impacts were numerically lower, both on-farm and off-farm, differences were not statistically significant. Nitrogen losses to air and water decreased by on average 5 to 10% when INC farming would be implemented for the whole region. The impact of INC farming on the global warming potential and eutrophication potential was, however, almost negligible (<2%) at regional level. This was due to a negligible impact on the methane emissions and on the surplus and thereby on the soil accumulation and losses of phosphorus to water at INC farms, illustrating the focus of these farms on closing the nitrogen cycle.

Quantifying the effect of heat stress on daily milk yield and monitoring dynamic changes using an adaptive dynamic model

Automation and use of robots are increasingly being used within dairy farming and result in large amounts of real time data. This information provides a base for the new management concept of precision livestock farming. From 2003 to 2006, time series of herd mean daily milk yield were collected on 6 experimental research farms in the Netherlands. These time series were analyzed with an adaptive dynamic model following a Bayesian method to quantify the effect of heat stress. The effect of heat stress was quantified in terms of critical temperature above which heat stress occurred, duration of heat stress periods, and resulting loss in milk yield. In addition, dynamic changes in level and trend were monitored, including the estimation of a weekly pattern. Monitoring comprised detection of potential outliers and other deteriorations. The adaptive dynamic model fitted the data well; the root mean squared error of the forecasts ranged from 0.55 to 0.99 kg of milk/d. The percentages of potential outliers and signals for deteriorations ranged from 5.5 to 9.7%. The Bayesian procedure for time series analysis and monitoring provided a useful tool for process control. Online estimates (based on past and present only) and retrospective estimates (determined afterward from all data) of level and trend in daily milk yield showed an almost yearly cycle that was in agreement with the calving pattern: most cows calved in winter and early spring versus summer and autumn. Estimated weekly patterns in terms of weekday effects could be related to specific management actions, such as change of pasture during grazing. For the effect of heat stress, the mean estimated critical temperature above which heat stress was expected was 17.8±0.56°C. The estimated duration of the heat stress periods was 5.5±1.03 d, and the estimated loss was 31.4±12.2 kg of milk/cow per year. Farm-specific estimates are helpful to identify management factors like grazing, housing and feeding, that affect the impact of heat stress. The effect of heat stress can be decreased by modifying these factors.

Invited review: A position on the Global Livestock Environmental Assessment Model (GLEAM)

The livestock sector is one of the fastest growing subsectors of the agricultural economy and, while it makes a major contribution to global food supply and economic development, it also consumes significant amounts of natural resources and alters the environment. In order to improve our understanding of the global environmental impact of livestock supply chains, the Food and Agriculture Organization of the United Nations has developed the Global Livestock Environmental Assessment Model (GLEAM). The purpose of this paper is to provide a review of GLEAM. Specifically, it explains the model architecture, methods and functionality, that is the types of analysis that the model can perform. The model focuses primarily on the quantification of greenhouse gases emissions arising from the production of the 11 main livestock commodities. The model inputs and outputs are managed and produced as raster data sets, with spatial resolution of 0.05 decimal degrees. The Global Livestock Environmental Assessment Model v1.0 consists of five distinct modules: (a) the Herd Module; (b) the Manure Module; (c) the Feed Module; (d) the System Module; (e) the Allocation Module. In terms of the modelling approach, GLEAM has several advantages. For example spatial information on livestock distributions and crops yields enables rations to be derived that reflect the local availability of feed resources in developing countries. The Global Livestock Environmental Assessment Model also contains a herd model that enables livestock statistics to be disaggregated and variation in livestock performance and management to be captured. Priorities for future development of GLEAM include: improving data quality and the methods used to perform emissions calculations; extending the scope of the model to include selected additional environmental impacts and to enable predictive modelling; and improving the utility of GLEAM output.

Greenhouse gas emissions of Spanish sheep farming systems: allocating between meat production and ecosystem services

Maternal abilities and piglet vitality were analyzed on 24 Meishan (MS) and 24 Large White (LW) gilts. Females were inseminated with a mixture of semen from both breeds. Three MS and 3 LW boars were used to constitute 3 duos formed by mixing of MS and LW semen in equal proportions. Farrowing events were studied over 5 successive batches. The proportion of purebred and crossbred piglets within the litter varied according to the duo used and the dam breed (p<0.01). The average within-litter percentage of purebred piglets in LW and MS sows was respectively 43% and 50% with use of duo 1, 64% and 23% with duo 2 and 69% and 81% with duo 3. Gestation was shorter in MS than in LW sows (111.6 vs 114.0 days; p<0.05) and litter size tended to be larger in LW than in MS sows (14.6 vs 12.8 total born piglets; p=0.08). Over the three first days of lactation, piglet probability of survival was similar between purebred and crossbred piglets born from LW sows (94.5% vs 95.0%) and higher in purebred than crossbred piglets born from MS sows (96.6% vs 98.7%, p<0.05). In LW sows, crossbred piglets were heavier at birth and more reactive in a novel environment than purebred piglets (1.29 vs 1.21 kg, p<0.10; reactivity score: 1.38 vs 1.03 respectively). In MS sows, purebred piglets had a lower birth weight than crossbred piglets but showed similar vitality (0.86 vs 1.08 kg, p<0.001; reactivity score: 1.00 vs 1.03). Birth process and piglet behavior in early lactation will be analyzed to estimate the interaction between dam breed and piglet genetic type (purebred vs crossbred) on the expression of maternal behavior and piglet vitality (udder activity and survival).Young horses normally live in small year-round stable groups including one stallion, their mothers, a few other mares, their siblings and unrelated peers. On the contrary, most of young domestic horses are generally maintained in same-age and same-sex groups from weaning until training. One has to consider that the absence of adult partners during ontogeny may be a source of behavioral disorders. In a first study, we focused on social conditions at weaning. While it is well known that presence of peers is of high importance to alleviate weaning stress, we investigated here the effects of the introduction of unrelated adult mares in groups of weanlings. Results showed that signs of stress were less pronounced and shorter in time in weanlings housed with adult mares than in weanlings kept in same-age groups (e.g. distress vocalizations: P<0.05; salivary cortisol: P<0.05). Besides, only foals deprived of adult presence exhibited increased aggressiveness towards peers (P<0.05) and abnormal behaviors (P<0.05). In conclusion, the presence of two unrelated adults in groups of weanlings not only alleviated weaning stress, but also favored positive social behavior and limited the emergence of abnormal behaviors. In a second study, we examined the impact of the temporary presence of adult horses on the behavior of 1- and 2-year-old horses. Results showed that young horses reared in homogeneous groups had a reduced behavioral repertoire, no real preferred partner and displayed many agonistic interactions compared to domestic horses reared under more natural conditions. Interestingly, after the introduction of adults, young horses expressed new behaviors (e.g. snapping, lying recumbent), preferential social associations emerged (P<0.05) and positive social behavior increased (P<0.05). Taken together, these results have important implications in terms of husbandry, indicating the importance of keeping young horses with adults.The aim of this work was to characterise the European consumer of pig meat (within ALCASDE project). A total of 822 respondents participated in a survey that was carried out Germany (DE n=132), Spain (ES n=133), France (FR n=139), Italy (IT n=140), Netherlands (NL n=132) and United Kingdom (UK n=146). All of them were selected for consuming pork > 1 time/month and stratified by age and gender, within each country profile. Respondents answered socio-demographic questions and frequency of consumption of different pork products, the most common purchasing place for fresh pork meat, if they were responsible for buying fresh pork at home, if they were responsible for cooking at home, and if they usually eat the pork with the fat. Data was analysed with FREQ procedure of SAS software. In general, over ninety percent of consumers ate fresh pork > 2 times/week (DE 96.2 %; ES 95.5 %; IT 92.9 %; NL 93.9 %; UK 97.3 %) except for FR (34.8 %). The most consumed product was the sausage in DE, dry cured ham in ES and IT; cooked ham in FR, mince meat in NL and sliced bacon in UK. In all the countries, the supermarket was the most common purchasing place of fresh pork with the exception of NL, where it was the traditional market. In general, the percentage of respondents responsible for buying fresh pork in their household was 91.0 %. In all countries, women were more responsible for buying fresh pork than men, and they were mostly between 41-60 years old. Ninety-one percent of respondents were partially responsible for cooking at home. Women were more responsible for cooking at home than men. France was an exception, where 49.6 % women and 50.4 % men cooked at home. Considering all respondents, 44.5 % ate the pork with the fat in all the countries (35.4 % of women and 54.6 % of men). The study showed differences among countries regarding respondents’ traits.