Oosting S J, Udo H M J, Viets T C
Animal Production Systems Group,Wageningen University,PO Box 338 6700 AH,Wageningen,The Netherlands.
Animal. 2014 Aug;8(8):1238-48. doi: 10.1017/S1751731114000548. Epub 2014 Mar 27.
Because of an increasing demand for animal-source foods, an increasing desire to reduce poverty and an increasing need to reduce the environmental impact of livestock production, tropical farming systems with livestock must increase their productivity. An important share of the global human and livestock populations are found within smallholder mixed-crop-livestock systems, which should, therefore, contribute significantly towards this increase in livestock production. The present paper argues that increased livestock production in smallholder mixed-crop-livestock systems faces many constraints at the level of the farm and the value chain. The present paper aims to describe and explain the impact of increased production from the farm and farmers' perspective, in order to understand the constraints for increased livestock production. A framework is presented that links farming systems to livestock value chains. It is concluded that farming systems that pass from subsistence to commercial livestock production will: (1) shift from rural to urban markets; (2) become part of a different value chain (with lower prices, higher demands for product quality and increased competition from peri-urban producers and imports); and (3) have to face changes in within-farm mechanisms and crop-livestock relationships. A model study showed that feed limitation, which is common in tropical farming systems with livestock, implies that maximum herd output is achieved with small herd sizes, leaving low-quality feeds unutilised. Maximal herd output is not achieved at maximal individual animal output. Having more animals than required for optimal production - which is often the case as a larger herd size supports non-production functions of livestock, such as manure production, draught, traction and capital storage - goes at the expense of animal-source food output. Improving low-quality feeds by treatment allows keeping more animals while maintaining the same level of production. Ruminant methane emission per kg of milk produced is mainly determined by the level of milk production per cow. Part of the methane emissions, however, should be attributed to the non-production functions of ruminants. It was concluded that understanding the farm and farmers' perceptions of increased production helps with the understanding of productivity increase constraints and adds information to that reported in the literature at the level of technology, markets and institutions.
由于对动物源食品的需求不断增加，减少贫困的愿望日益强烈，以及降低畜牧业生产对环境影响的需求不断上升，热带地区的农牧结合养殖系统必须提高其生产力。全球很大一部分人类和牲畜都处于小农户的混合作物-牲畜养殖系统中，因此，这一系统应为牲畜产量的增加做出重大贡献。本文认为，小农户混合作物-牲畜养殖系统中牲畜产量的增加在农场层面和价值链层面面临许多制约因素。本文旨在从农场和农民的角度描述和解释产量增加的影响，以便了解牲畜产量增加的制约因素。本文提出了一个将养殖系统与牲畜价值链联系起来的框架。得出的结论是，从自给自足型转变为商业化牲畜生产的养殖系统将：（1）从农村市场转向城市市场；（2）成为不同价值链的一部分（价格更低、对产品质量要求更高，且来自城郊生产者和进口产品的竞争加剧）；（3）必须面对农场内部机制和作物-牲畜关系的变化。一项模型研究表明，饲料限制在热带地区的农牧结合养殖系统中很常见，这意味着在畜群规模较小时就能实现最大畜群产量，而低质量饲料则未得到利用。最大畜群产量并非在个体动物产量最大化时实现。拥有超过最佳生产所需数量的牲畜——这种情况很常见，因为较大的畜群规模有助于实现牲畜的非生产功能，如粪便生产、役用、牵引和资本储存——是以牺牲动物源食品产量为代价的。通过处理改善低质量饲料可以在保持相同生产水平的同时饲养更多牲畜。每生产1千克牛奶，反刍动物的甲烷排放量主要取决于每头奶牛的产奶量。然而，部分甲烷排放应归因于反刍动物的非生产功能。得出的结论是，了解农场和农民对产量增加的看法有助于理解生产力提高的制约因素，并为技术、市场和机构层面的文献报道增添信息。
