Li Pengzhen, Zhang Zhenhao, Monaco Thomas A, Rong Yuping
Department of Grassland Resource and Ecology, College of Grassland Science and Technology China Agricultural University Beijing China.
U.S. Department of Agriculture, Agricultural Research Service, Forage and Range Research Laboratory Utah State University Logan Utah USA.
Ecol Evol. 2024 Nov 18;14(11):e70609. doi: 10.1002/ece3.70609. eCollection 2024 Nov.
Grazing livestock in grasslands face the challenge of obtaining sufficient nutrition due to uneven distribution of plant species and fluctuating vegetation productivity and nutrient levels. In northern China, and are the dominant perennial species in native grasslands, but they provide limited nutrition compared to forbs with higher crude protein (CP) content. While dietary ingredients can affect the nutritional intake of grazing livestock, the influence of different grazing strategies on dietary selection remains unclear. In this study, three sheep grazing strategies (lambs alone, mixed lambs and ewes, and ewes alone) were used to explore dietary selection. We investigated the influence of vegetation characteristic (above-ground biomass production, height, and species diversity) and foraging behavior (feed intake, organic matter digestibility, and daily grazing time) on the mechanisms of dietary selection (taxonomic family richness and composition). Forage consumption across the grazing strategies revealed that species from Poaceae, Rosaceae, and Cyperaceae families were frequently consumed. Both ewes and lambs in the mixed-grazing strategy preferentially consumed forbs with diverse species composition (Jacob's > 0), which contained higher CP than those available in the overall vegetation ( < 0.05). In addition, dietary richness was significantly ( < 0.05) influenced by vegetation species diversity except for animals in the lambs alone strategy. Compared to lambs in mixed-grazing, lambs alone had both greater daily grazing time and consumption of grass with lower digestibility ( < 0.05). Our study is the first to demonstrate that lambs can develop a similar dietary selection and behavioral pattern when grazing with adult ewes in temperate grasslands. Our study indicates that the conservation of species diversity in native grasslands is critically beneficial to livestock nutrition.
草原上放牧的牲畜面临着挑战，因为植物物种分布不均以及植被生产力和养分水平波动，难以获得足够的营养。在中国北方，羊草和针茅是天然草原上的优势多年生物种，但与粗蛋白（CP）含量较高的杂类草相比，它们提供的营养有限。虽然日粮成分会影响放牧牲畜的营养摄入，但不同放牧策略对日粮选择的影响仍不清楚。在本研究中，采用了三种绵羊放牧策略（单独放牧羔羊、混合放牧羔羊和母羊、单独放牧母羊）来探索日粮选择。我们研究了植被特征（地上生物量产量、高度和物种多样性）和觅食行为（采食量、有机物消化率和每日放牧时间）对日粮选择机制（分类科丰富度和组成）的影响。不同放牧策略下的牧草消耗情况表明，禾本科、蔷薇科和莎草科的物种经常被采食。混合放牧策略中的母羊和羔羊都优先采食物种组成多样的杂类草（雅各布指数＞0），这些杂类草的粗蛋白含量高于整个植被中的含量（P＜0.05）。此外，除了单独放牧羔羊的策略中的动物外，日粮丰富度受到植被物种多样性的显著影响（P＜0.05）。与混合放牧的羔羊相比，单独放牧的羔羊每日放牧时间更长，且采食的草消化率更低（P＜0.05）。我们的研究首次表明，在温带草原上与成年母羊一起放牧时，羔羊可以形成相似的日粮选择和行为模式。我们的研究表明，保护天然草原的物种多样性对牲畜营养至关重要。
