1School of Biosciences, University of Nottingham,Sutton Bonington Campus,Loughborough,Leics LE12 5RD,UK.
2School of Veterinary Sciences,University of Bristol,Langford,Somerset BS40 5DU,UK.
Animal. 2018 Aug;12(8):1735-1743. doi: 10.1017/S175173111700218X. Epub 2017 Sep 12.
The drive to increase the output of animal product in some sectors of ruminant livestock production has led to greater use of feeds such as cereal grains and soyabean meal that are potentially human-edible. This trend has caused concern since, by so doing, ruminants compete not only with monogastric livestock but also with the human population for a limited global area of cultivatable land on which to produce grain crops. Reasons for using potentially human-edible feeds in ruminant diets include increased total daily energy intake, greater supply of essential amino acids and improved ruminal balance between fermentable energy and degradable protein. Soyabean meal, produced on land that has been in arable cultivation for many years can fulfil a useful role as a supplier of undegraded dietary protein in diets for high-yielding dairy cows. However, in the context of sustaining the production of high-quality foods from livestock to meet the demands of a growing human population, the use of potentially human-edible feed resources by livestock should be restricted to livestock with the highest daily nutrient requirements; that is, potentially human-edible feed inputs should be constrained to meeting requirements for energy and protein and to rectifying imbalances in nutrient supply from pastures and forage crops such as high concentrations of nitrogen (N). There is therefore a role for human-edible feeds in milk production because forage-only systems are associated with relatively low output per head and also low N use efficiency compared with systems with greater reliance on human-edible feeds. Profitability on farm is driven by control of input costs as well as product value and examples are given of low-cost bovine milk and meat production with little or no reliance on potentially human-edible feeds. In beef production, the forage-only systems currently under detailed real-time life-cycle analysis at the North Wyke Farm Platform, can sustain high levels of animal growth at low feed cost. The potential of all-forage diets should be demonstrated for a wide range of ruminant milk and meat production systems. The challenge for the future development of ruminant systems is to ensure that potentially human-edible feeds, or preferably human-inedible by-products if available locally, are used to complement pastures and forage crops strategically rather than replace them.
提高反刍家畜生产某些部门动物产品产量的动力导致更多地使用谷物和豆粕等潜在可食用饲料。这种趋势引起了关注，因为这样一来，反刍动物不仅与单胃动物竞争，而且还与人类争夺可用于种植粮食作物的有限全球耕地。反刍动物日粮中使用潜在可食用饲料的原因包括增加每日总能量摄入、增加必需氨基酸供应以及改善瘤胃中可发酵能量与可降解蛋白质之间的平衡。在高产奶牛日粮中，多年来一直用于耕地种植的豆粕可以作为未降解日粮蛋白质的有用来源。然而，在维持生产高质量食品以满足不断增长的人口需求的背景下，应将潜在可食用饲料资源的使用限制在每日营养需求最高的牲畜上；也就是说，潜在可食用饲料的投入应限制在满足能量和蛋白质需求以及纠正牧场和草料作物（如高浓度氮）供应的营养平衡方面。因此，人类食用饲料在牛奶生产中具有一定的作用，因为仅草料系统与每头产量相对较低以及与对人类食用饲料依赖性较高的系统相比，氮利用效率也较低。农场的盈利能力取决于对投入成本以及产品价值的控制，并且举例说明了对潜在可食用饲料依赖度低的低成本奶牛和肉类生产。在牛肉生产中，目前在北怀克农场平台进行详细实时生命周期分析的仅草料系统可以以低饲料成本维持高水平的动物生长。应展示所有草料日粮的潜力，适用于广泛的反刍动物牛奶和肉类生产系统。反刍动物系统未来发展的挑战是确保潜在可食用饲料（如果当地有不可食用的副产品更好）被战略性地用作牧场和草料作物的补充，而不是替代它们。
