Since protein content and quality were high and comparable for prepupae reared on different substrates, black soldier fly could be an interesting protein source for animal feeds. However, differences in EE and ash content as a function of substrate should be considered. © 2016 Society of Chemical Industry.

Purpose Livestock already use most global agricultural land, whereas the demand for animal-source food (ASF) is expected to increase. To address the contribution of livestock to global food supply, we need a measure for land use efficiency of livestock systems. Methods Existing measures capture different aspects of the debate about land use efficiency of livestock systems, such as plant productivity and the efficiency of converting feed, especially human-inedible feed, into animal products. So far, the suitability of land for cultivation of food crops has not been accounted for. Our land use ratio (LUR) includes all above-mentioned aspects and yields a realistic insight into land use efficiency of livestock systems. LUR is defined as the maximum amount of human-digestible protein (HDP) derived from food crops on all land used to cultivate feed required to produce 1 kg ASF over the amount of HDP in that 1 kg ASF. We illustrated our concept for three case systems. Results and discussion The LUR for the case of laying hens equaled 2.08, implying that land required to produce 1 kg HDP from laying hens could directly yield 2.08 kg HDP from human food crops. For dairy cows, the LUR was 2.10 when kept on sandy soils and 0.67 when kept on peat soils. The LUR for dairy cows on peat soils was lower compared to cows on sandy soils because land used to grow grass and grass silage for cows on peats was unsuitable for direct production of food crops. A LUR <1.0 is considered efficient in terms of global food supply and implies that animals produce more HDP per square metre than crops. Conclusions Values <1.0 demonstrate that livestock produce HDP more efficiently than crops. Such livestock systems (with a LUR<1.0), therefore, do have a role in future food supply and therefore contribute to food security. Our LUR offers identification of livestock production systems that contribute to global food supply, i.e. systems that value land with low opportunity costs for arable production and/or byproducts from crop cultivation or the food or energy industry.

The abolition of the Dutch milk quota system has been accompanied by the introduction of a new manure policy to limit phosphate production (i.e., excretion via manure) on expanding dairy farms. The objective of this study was to evaluate the effect of these recent policy changes on the farm structure, management, labor income, nitrogen and phosphate surpluses, and greenhouse gas emissions of an average Dutch dairy farm. The new manure policy requires that any increase in phosphate production be partly processed and partly applied to additional farmland. In addition, phosphate quotas have been introduced. Herein, we used a whole-farm optimization model to simulate an average farm before and after quota abolition and introduction of the new manure policy. The objective function of the model maximized labor income. We combined the model with a farm nutrient balance and life-cycle assessment to determine environmental impact. Based on current prices, increasing the number of cows after quota abolition was profitable until manure processing or additional land was required to comply with the new manure policy. Manure processing involved treatment so that phosphate was removed from the national manure market. Farm intensity in terms of milk per hectare increased by about 4%, from 13,578kg before quota abolition to 14,130kg after quota abolition. Labor income increased by €505/yr. When costs of manure processing decreased from €13 to €8/t of manure or land costs decreased from €1,187 to €573/ha, farm intensity could increase up to 20% until the phosphate quota became limiting. Farms that had already increased their barn capacity to prepare for expansion after milk quota abolition could benefit from purchasing extra phosphate quota to use their full barn capacity. If milk prices increased from €355 to €420/t, farms could grow unlimited, provided that the availability of external inputs such as labor, land, barn capacity, feed, and phosphate quota at current prices were also unlimited. The milk quota abolition, accompanied by a new manure policy, will slightly increase nutrient losses per hectare, due to an increase in farm intensity. Greenhouse gas emissions per unit of milk will hardly change, so at a given milk production per cow, total greenhouse gas emissions will increase linearly with an increase in the number of cows.

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In many intensive dairy regions in northwest Europe, a decline in grazing is observed. In the Netherlands, the proportion of dairy cows with access to pasture is declining, as well as the time spent grazing per cow. The decline in grazing is seen as an unwanted trend by many stakeholders and is, thus, under debate amongst dairy farmers, the dairy chain, and society. Therefore, a public–private partnership was initiated to encourage grazing by providing farmers with usable means of improving their grazing systems. The partnership involved stakeholders from the dairy farming community, dairy and feed industry, agrotechnical industries, advisory services, and research. The objective of this partnership was to develop and stimulate technological innovations and management measures that increase fresh grass intake at pasture. The innovation network combined an integrated research approach with farmer working groups and broader stakeholder interactive meetings. The project started with a comprehensive grass intake framework, which was the foundation for exploration of innovations. The framework consisted of six interlinked components: soil, grass growth, grass supply, grass intake, feed supplementation, and cow behavior. In a continuous interactive cycle, strategic choices were made to focus on potentially effective innovations. The use of a public–private partnership to develop usable innovations that encourage grazing practices proven to be a good approach to develop a shared vision among stakeholders. It provided a basis to work together toward innovative practices and to disseminate the outcomes to the foreseen users. The approach succeeded in design concepts for two specific innovations, i.e., weekly grass growth predictions and daily fresh grass intake tracking. We demonstrated that meaningful grazing and fresh grass intake are possible in intensive dairy systems with high stocking rates and high levels of supplementary feeding.

This version is distributed under a non-commercial no derivatives Creative Commons (CC-BY-NC-ND) user license, which permits use, distribution, and reproduction in any medium, provided the original work is properly cited and not used for commercial purposes. Further, the restriction applies that if you remix, transform, or build upon the material, you may not distribute the modified material.

Dit onderzoek is uitgevoerd in het kader van het publiek-private samenwerkingsprogramma "Ruwvoerproductie en Bodemmanagement" (www.ruwvoerenbodem.nl).

Goed weiden verlaagt de productiekosten van melk en draagt bij aan het positieve imago van de melkveehouderij. Maar beweiden is wel een vak! Om dit vak beter uit te kunnen oefenen zet het Bouwstenenboek Beweiding nieuwe kennis uit Amazing Grazing op een rij.