Long-term declines in dietary nutritional quality for North American cattle

With over 1 billion cattle in the world as well as over 2 billion sheep, goats and buffalo, these animals contribute approximately 15% of the global human protein supply while producing a significant proportion of anthropogenic emissions of greenhouse gases and global nutrient fluxes. Despite increasing reliance on grazers for protein production globally, the future of grazers in a changing world is uncertain. Factors such as increased prevalence of drought, rising atmospheric CO2 concentrations, and sustained nutrient export all have the potential to reduce cattle performance by reducing the nutritional quality of forage. However, there are no analyses to quantify changes in diet quality, subsequent impact on cattle performance and cost of supplementation necessary to mitigate any predicted protein deficiency. To quantify the trajectory of nutritional stress in cattle, we examined more than 36 000 measurements of dietary quality taken over 22 yr for US cattle. Here, we show that standa...

全球现存肉牛超10亿头，绵羊、山羊与水牛总计超20亿只。此类家畜为全球人类提供了约15%的蛋白质供给，同时也产生了占比可观的人为温室气体排放与全球营养通量。尽管全球范围内对放牧家畜作为蛋白质来源的依赖程度日益提升，但在气候变化的大背景下，放牧养殖业的未来仍充满不确定性。干旱频发、大气CO₂浓度升高以及持续的养分输出等诸多因素，均可能通过降低饲草的营养品质，削弱肉牛的生产性能。然而目前尚无相关研究分析，能够量化饲粮品质的变化、其对肉牛生产性能的后续影响，以及缓解预估蛋白质缺乏所需的补饲成本。为了量化肉牛营养应激的发展趋势，我们针对美国肉牛开展了一项研究，收集了为期22年间累计超过3.6万条饲粮品质测量数据。在此，我们的研究结果显示……