Modelling the effect of context-specific greenhouse gas and nitrogen emission mitigation options in key European dairy farming systems

Understanding the environmental consequences associated with dairy cattle production systems is crucial for the implementation of targeted strategies for emission reduction. However, few studies have modelled the effect of tailored emission mitigation options across key European dairy production systems. Here, we assess the single and combined effect of six emission mitigation practises on selected case studies across Europe through the Sustainable and Integrated Management System for Dairy Production model. This semi-mechanistic model accounts for the interacting flows from a whole-farm perspective simulating the environmental losses in response to different management strategies and site-specific conditions. The results show how reducing the crude protein content of the purchased fraction of the diet was an adequate strategy to reduce the greenhouse gas and nitrogen emission intensity in all systems. Furthermore, implementing an anaerobic digestion plant reduced the greenhouse gas emissions in all tested case studies while increasing the nitrogen emissions intensity, particularly when slurry was applied using broadcast. Regarding the productivity increase, contrasting effects were observed amongst the case studies modelled. Moreover, shallow slurry injection effectively mitigated the intensity of nitrogen losses from the fields due to strong reductions in ammonia volatilisation. When substituting urea with ammonium nitrate as mineral fertiliser, site-specific conditions affected the mitigation potential observed, discouraging its application on sandy-loam soils. Rigid slurry covers effectively reduced the storage-related nitrogen emissions intensity while showing a minor effect on total greenhouse gas emission intensity. In addition, our results provide novel evidence regarding the advantages of cumulative implementation of adapted mitigation options to offset the negative trade-offs of single-option applications (i.e. slurry covers or anaerobic digestion and slurry injection). Through this study, we contribute to a better understanding of the effect of emission mitigation options across dairy production systems in Europe, thus facilitating the adoption of tailored and context-specific emission reduction strategies

Performance and digestive function of broiler chickens given grit in the diet

1. A series of experiments were carried out to study the effect of grit on broiler performance, gizzard development and fate of grit in the digestive tract. 2. In Experiment 1, performance, gizzard weight and content of grit in the gizzard of broiler chickens given access to granite-type grit was investigated. In Experiment 2, the effect of grit stones on performance and gizzard development was assessed in diets with or without whole wheat. 3. In Experiment 3, the effect of grit in the form of zeolite, granite or marble on gizzard development and digestive tract grinding and passage was studied in diets with or without whole wheat. 4. Grit stones had no effect on performance of broiler chickens, which may be explained by the fact that grit stones did not stimulate gizzard development to the same extent as with other structural materials. 5. The lack of stimulation is at least partly due to the fact that a majority of the grit stones eaten pass through the small intestine without being retained in the gizzard. 6. Grit in the form of marble reduced feed intake and weight gain.acceptedVersio

Performance and digestive function of broiler chickens given grit in the diet

1. A series of experiments were carried out to study the effect of grit on broiler performance, gizzard development and fate of grit in the digestive tract. 2. In Experiment 1, performance, gizzard weight and content of grit in the gizzard of broiler chickens given access to granite-type grit was investigated. In Experiment 2, the effect of grit stones on performance and gizzard development was assessed in diets with or without whole wheat. 3. In Experiment 3, the effect of grit in the form of zeolite, granite or marble on gizzard development and digestive tract grinding and passage was studied in diets with or without whole wheat. 4. Grit stones had no effect on performance of broiler chickens, which may be explained by the fact that grit stones did not stimulate gizzard development to the same extent as with other structural materials. 5. The lack of stimulation is at least partly due to the fact that a majority of the grit stones eaten pass through the small intestine without being retained in the gizzard. 6. Grit in the form of marble reduced feed intake and weight gain