The Resources Requirement,Nitrogen And Phosphorus Use And Losses In The Main Livestock Production System In China

With the rapid increase of animal food demand, the livestock production was booming developed and largely shifted from traditional production system to more industrialized production system in China. The agriculture resources scarcity and environmental pollution was enhanced as the consequence of these changes. There were few studies evaluated the nutrient flow livestock production. However, there was little information about the differences between different animal categories and different production systems. Hence, we build a NUFER-animal model, through literature review, survey and simulation model, which allowed calculate the resource requirement, nutrtient use and losses of the main animal categories (dairy cattle, beef cattle, layers, broilers, pigs) and main production systems (traditional, grazing, medium size and industrial farms) at the national level in China. And use pig production as an example, evaluated the impacts of animal population and production structure changes on the resources use and nutrient losses. Several options were explored for the future pig production through scenario analysis. The main results are as below:(1) According to the calculation of the model, to produce1kg of pork, chicken meat, beef, eggs and milk,5.0,3.5,27,3.2and2.1kg feed was required, respectively. The amount of land and fertilizer requirement to produce these feed of different production systems were also calculated, and mainly following the order:dairy cattle<pigs<layers<broilers<beef cattle.(2) We also quantified the nitrogen and phosphorus use efficiency (NUE and PUE) at the animal level, herd level and "soil-feed-animal" system level. At the animal level, the layers and broilers production shared the similar NUE, and was much higher than dairy and pigs production system. At the herd level, the NUE was followed in the order:layers (39%)> broilers (37%)> pigs (21%)> dairy cattle (15%)> beef cattle (3.2%). At the system level, the NUE differences with different animal categories was narrowed, and followed the order:Pigs (30%)≈Layers (29%)> Broilers (26%)> Dairy (24%)> Beef cattle (16%).(3) For production1kg of nitrogen (N) in the products, the average N losses through the whole production chain was followed the order:beef cattle (31kg N)> dairy (7.0kg N)> pigs (3.8kg N)> broilers (2.5kg N)> layers (2.3kg N). However, almost a reverse trend was showed when1kg of phosphorus (P) was produced by different production system. The P losses from different system was followed the order:layers (4.2kg P)> broilers (2.1kg P)> pigs (2.1kg P)> beef cattle (0.7kg P)> dairy (0.3kg P).(4) The resources requirements varied between different productions systems. Basically, to produce1kg product, traditional and grazing system required lower amount arable land and fertilizer than medium size and industrial farms. However, traditional and grazing systems used more feed to produce lkg of product than medium size and industrial farms.(5) At the animal and herd level, the traditional systems showed lower nutrient use efficiency than medium size and industrial farms for all the animal categories, except for layers and broilers. However, at the system level, the traditional systems showed much higher nutrient use efficiency, due to higher crop-livestock integration rate. Such as the nitrogen use efficiency at the system level of different dairy production system was following the order:traditional (50%)> grazing (38%)> collective feedlot (16%)> industrial feedlot (10%).(6) To produce1kg of nitrogen in the products, more nitrogen lost to the environment in traditional systems compared with industrial farms for all the animal categories, except for layers and broilers. For example, to produce1kg of nitrogen in the chicken meat,0.7kg nitrogen lost in the traditional broiler production system, however about3.0and2.5kg of nitrogen lost to environment in medium size and industrial broilers farms, respectively. In dairy production systems, when1kg milk nitrogen was produced, up to10kg of nitrogen lost in traditional system which was higher than6.3kg nitrogen in industrial system.(7) We also found that the resources requirement, nutrient use and losses were greatly impacted by the changes of production structure. Such as, pig production changed from backyard system to industrial system largely improved the nutrient use efficiency at the animal and herd level. However, the nutrient recycling at the system level decreased rapidly. The scenario results indicated that, the single mitigation options was less efficient in reducing the nutrient losses. If all the mitigation options were combined, the total N and P losses could be reduced by64%and95%.