Weinert-Nelson Jennifer R, Meyer William A, Williams Carey A
Department of Animal Sciences, Rutgers, The State University of New Jersey, New Brunswick, NJ 08901, USA.
Department of Plant Biology, Rutgers, The State University of New Jersey, New Brunswick, NJ 08901, USA.
Transl Anim Sci. 2021 Oct 26;5(4):txab208. doi: 10.1093/tas/txab208. eCollection 2021 Oct.
Integration of warm-season grasses into traditional cool-season pastures can increase summer forage for grazing cattle. The aim of this study was to determine impacts of this practice on yield and nutrient composition of equine rotational pasture systems as well as horse body condition. Two 1.5 ha rotational systems (6 to 0.25 ha sections/system) were evaluated: a control system (CON) (all sections mixed cool-season grass [CSG-CON]) and an integrated rotational grazing system (IRS) (three CSG sections [CSG-IRS] and three crabgrass [ (L.) Scop.; CRB-IRS]). Three horses per system grazed in three periods: EARLY (mid-May to mid-July), SLUMP (mid-July to mid-September), and LATE (mid-September to mid-November). Herbage mass (HM) was measured prior to each rotation and samples were collected (0800 to 1000 h) for nutrient analysis. Grazing days were tracked to calculate carrying capacity (CC). Horse condition measures were assessed monthly. Over the full grazing season, 9,125 kg of forage was available for grazing in IRS versus 6,335 kg in CON. The CC was 390 horse d for IRS, while only 276 horse d for CON. Total HM/section did not differ during EARLY when CRB was not available (CSG-IRS: 2,537 ± 605; CSG-CON: 3,783 ± 856 kg/ha), but CC was greater in CSG-IRS (220 ± 37 horse d/ha) than CSG-CON (92 ± 26 horse d/ha; = 0.03). In SLUMP, both HM and CC were greater in CRB-IRS (HM: 4,758 ± 698 kg/ha; CC: 196 ± 31 horse d/ha) than CSG-IRS (HM: 1,086 ± 698 kg/ha; CC: 32 ± 31 horse d/ha) or CON (HM: 970 ± 493 kg/ha; CC: 46 ± 22 horse d/ha; 0.02). While HM did not differ by section type in LATE (1,284 ± 158 kg/ha), CC was greater in CSG-CON (84 ± 9 horse d/ha) versus CRB-IRS (32 ± 13 horse d/ha; = 0.03) and CSG-IRS (40 ± 13 horse d/ha; = 0.06). During SLUMP, water-soluble carbohydrates (WSC) were lower in CRB-IRS (4.46% ± 0.80%) than CSG-CON (7.92% ± 0.90%; 0.04), but not CSG-IRS (5.93% ± 1.04%); however, non-structural carbohydrates (NSC) did not differ (7.05% ± 0.62%). There were no differences in WSC (6.46% ± 0.54%) or NSC (7.65% ± 0.54%) by section type in LATE. Horses in IRS maintained a body condition score (BCS) of 5.78 ± 0.48, but BCS did not differ by system (CON: 6.11 ± 0.48). Thus, integrated grazing increased summer pasture yield and provided adequate nutrition to maintain horse condition, but further research is needed to improve late-season production. Integrated grazing may not, however, provide an advantage in limiting dietary NSC, as NSC remained low for all pasture sections.
将暖季型草融入传统冷季型牧场可增加夏季供放牧牛群食用的草料。本研究的目的是确定这种做法对马用轮牧系统的产量和营养成分以及马的体况的影响。评估了两个1.5公顷的轮牧系统（每个系统6个至0.25公顷的区域）：一个对照系统（CON）（所有区域混合种植冷季型草[CSG-CON]）和一个综合轮牧系统（IRS）（三个冷季型草区域[CSG-IRS]和三个马唐草区域[ (L.) Scop.；CRB-IRS]）。每个系统有三匹马分三个时期放牧：早期（5月中旬至7月中旬）、低迷期（7月中旬至9月中旬）和后期（9月中旬至11月中旬）。在每次轮牧前测量牧草质量（HM），并采集样本（08:00至10:00）进行营养分析。记录放牧天数以计算载畜量（CC）。每月评估马的体况指标。在整个放牧季节，IRS可供放牧的草料为9125千克，而CON为6335千克。IRS的载畜量为390马日，而CON仅为276马日。在早期，当没有马唐草时（CSG-IRS：2537±605；CSG-CON：3783±856千克/公顷），各区域的总HM没有差异，但CSG-IRS的载畜量（220±37马日/公顷）高于CSG-CON（92±26马日/公顷；P = 0.03）。在低迷期，CRB-IRS的HM和CC均高于CSG-IRS（HM：4758±698千克/公顷；CC：196±31马日/公顷）或CON（HM：970±493千克/公顷；CC：46±22马日/公顷；P<0.02）。在后期，各区域类型的HM没有差异（1284±158千克/公顷），但CSG-CON的载畜量（84±9马日/公顷）高于CRB-IRS（32±13马日/公顷；P = 0.03）和CSG-IRS（40±13马日/公顷；P = 0.06）。在低迷期，CRB-IRS的水溶性碳水化合物（WSC）含量（4.46%±0.80%）低于CSG-CON（7.92%±0.90%；P<0.04），但不低于CSG-IRS（5.93%±1.04%）；然而，非结构性碳水化合物（NSC）没有差异（7.05%±0.62%）。后期各区域类型的WSC（6.46%±0.54%）或NSC（7.65%±0.54%）没有差异。IRS中的马维持了5.78±0.48的体况评分（BCS），但不同系统间的BCS没有差异（CON：6.11±0.48）。因此，综合放牧提高了夏季牧场产量，并提供了足够的营养以维持马的体况，但需要进一步研究以提高后期产量。然而，综合放牧在限制日粮NSC方面可能没有优势，因为所有牧场区域的NSC仍然较低。
