Milk production & greenhouse gases : integrated modeling of feeding and breeding strategies to reduce emissions

WU thesis no. 577

Production, partial cash flows and greenhouse gas emissions of simulated dairy herds with extended lactations

The transition period is the most critical period in the lactation cycle of dairy cows. Extended lactations reduce the frequency of transition periods, the number of calves and the related labour for farmers. This study aimed to assess the impact of 2 and 4 months extended lactations on milk yield and net partial cash flow (NPCF) at herd level, and on greenhouse gas (GHG) emissions per unit of fat- and protein-corrected milk (FPCM), using a stochastic simulation model. The model simulated individual lactations for 100 herds of 100 cows with a baseline lactation length (BL), and for 100 herds with lactations extended by 2 or 4 months for all cows (All+2 and All+4), or for heifers only (H+2 and H+4). Baseline lactation length herds produced 887 t (SD: 13) milk/year. The NPCF, based on revenues for milk, surplus calves and culled cows, and costs for feed, artificial insemination, calving management and rearing of youngstock, was k€174 (SD: 4)/BL herd per year. Extended lactations reduced milk yield of the herd by 4.1% for All+2, 6.9% for All+4, 1.1% for H+2 and 2.2% for H+4, and reduced the NPCF per herd per year by k€7 for All+2, k€12 for All+4, k€2 for H+2 and k€4 for H+4 compared with BL herds. Extended lactations increased GHG emissions in CO2-equivalents per t FPCM by 1.0% for All+2, by 1.7% for All+4, by 0.2% for H+2 and by 0.4% for H+4, but this could be compensated by an increase in lifespan of dairy cows. Subsequently, production level and lactation persistency were increased to assess the importance of these aspects for the impact of extended lactations. The increase in production level and lactation persistency increased milk production of BL herds by 30%. Moreover, reductions in milk yield for All+2 and All+4 compared with BL herds were only 0.7% and 1.1% per year, and milk yield in H+2 and H+4 herds was similar to BL herds. The resulting NPCF was equal to BL for All+2 and All+4 and increased by k€1 for H+2 and H+4 due to lower costs for insemination and calving management. Moreover, GHG emissions per t FPCM were equal to BL herds or reduced (0% to -0.3%) when lactations were extended. We concluded that, depending on lactation persistency, extending lactations of dairy cows can have a positive or negative impact on the NPCF and GHG emissions of milk production.</p

Grazed and confused? : Ruminating on cattle, grazing systems, methane, nitrous oxide, the soil carbon sequestration question - and what it all means for greenhouse gas emissions

In the context of planetary boundaries on the one hand and the need for human development (in its widest sense) on the other, what role – if any – do farmed animals play in a sustainable food system? If they do have a role, which systems and species are to be preferred, in which contexts, at what scale and at what level of overall production and consumption? How could the required changes happen

The potential of future foods for sustainable and healthy diets

Altering diets is increasingly acknowledged as an important solution to feed the world’s growing population within the planetary boundaries. In our search for a planet-friendly diet, the main focus has been on eating more plant-source foods, and eating no or less animal-source foods, while the potential of future foods, such as insects, seaweed or cultured meat has been underexplored. Here we show that compared to current animal-source foods, future foods have major environmental benefits while safeguarding the intake of essential micronutrients. The complete array of essential nutrients in the mixture of future foods makes them good-quality alternatives for current animal-source foods compared to plant-source foods. Moreover, future foods are land-efficient alternatives for animal-source foods, and if produced with renewable energy, they also offer greenhouse gas benefits. Further research on nutrient bioavailability and digestibility, food safety, production costs and consumer acceptance will determine their role as main food sources in future diets

Nieuwe maat voor melkproductie : vergelijking melkgift koeien met verschillende droogstandslengte mogelijk met effectieve lactatie

De gebruikelijke maat voor lactatieproductie, de 305 dagenproductie, houdt geen rekening met de lengte van de droogstand of tussenkalftijd van de koe. Onderzoekers van Wageningen UR stellen daarom een nieuwe maat voor lactatieproductie voo

Future of animal nutrition: the role of life cycle assessment

The livestock sector poses severe pressure on the environment via the emissions of pollutants to air, water and soil, and via the use of scarce resources. This chapter elaborates on the role of life cycle assessment (LCA) to reduce environmental impacts of the pig and poultry sector, with special emphasis on the production of feed. First, the four phases of an LCA are described. Differences between attributional and consequential LCA, and variability in methods to account for land use change are discussed. It is concluded that harmonisation of methods and high quality inventory data are needed to improve interpretation of LCA results in the livestock sector. Second, the role of LCA in animal nutrition is discussed. Improving the production efficiency of crops and animals has been a major focus for reducing environmental impacts of livestock production. LCA implicitly combines information regarding crop and animal productivity, and creates understanding about the interaction between processes, and the impact of the entire production chain. Current applications of LCA are mainly attributional; results create understanding concerning the current situation, such as the environmental impact of a certain diet. To evaluate the impact of improvement options, consequential LCA is required. If a feed company increases its use of by-products, for example, the consequences of a decrease in availability of that by-product for other applications, such as biofuel production, need to be taken into account. A potential shortcoming of LCA is that is does not address the competition for resources between humans and animals, which occurs at a higher aggregation level. To determine an environmentally sustainable human diet, or to address the role of livestock in (global) food security, LCA needs to be combined with other modelling techniques that address environmental impacts of dietary choices at the national or international level

Future of animal nutrition: the role of life cycle assessment

The livestock sector poses severe pressure on the environment via the emissions of pollutants to air, water and soil, and via the use of scarce resources. This chapter elaborates on the role of life cycle assessment (LCA) to reduce environmental impacts of the pig and poultry sector, with special emphasis on the production of feed. First, the four phases of an LCA are described. Differences between attributional and consequential LCA, and variability in methods to account for land use change are discussed. It is concluded that harmonisation of methods and high quality inventory data are needed to improve interpretation of LCA results in the livestock sector. Second, the role of LCA in animal nutrition is discussed. Improving the production efficiency of crops and animals has been a major focus for reducing environmental impacts of livestock production. LCA implicitly combines information regarding crop and animal productivity, and creates understanding about the interaction between processes, and the impact of the entire production chain. Current applications of LCA are mainly attributional; results create understanding concerning the current situation, such as the environmental impact of a certain diet. To evaluate the impact of improvement options, consequential LCA is required. If a feed company increases its use of by-products, for example, the consequences of a decrease in availability of that by-product for other applications, such as biofuel production, need to be taken into account. A potential shortcoming of LCA is that is does not address the competition for resources between humans and animals, which occurs at a higher aggregation level. To determine an environmentally sustainable human diet, or to address the role of livestock in (global) food security, LCA needs to be combined with other modelling techniques that address environmental impacts of dietary choices at the national or international level

Comparing environmental impacts of beef production systems: A review of life cycle assessments

Livestock production, and especially beef production, has a major impact on the environment. Environmental impacts, however, vary largely among beef systems. Understanding these differences is crucial to mitigate impacts of future global beef production. The objective of this research, therefore, was to compare cradle-to-farm-gate environmental impacts of beef produced in contrasting systems. We reviewed 14 studies that compared contrasting systems using life cycle assessment (LCA). Systems studied were classified by three main characteristics of beef production: origin of calves (bred by a dairy cow or a suckler cow), type of production (organic or non-organic) and type of diet fed to fattening calves