Grass silage is the predominant conserved forage offered to ruminant livestock within Northern Ireland (NI) when housed. This study involved the analysis of a dataset (n = 76,452 samples) comprising silage samples from commercial farms, analysed by the Agri-Food and Biosciences Institute (AFBI) between 1998 and 2017. The effects of harvest number (1, 2 or 3) and year were examined. Most of the differences between harvests 1–3 were significant although these differences were of little biological significance. Silage crude protein (CP) increased from harvests 1 to 3, while ammonia N concentration was higher in 3rd harvests. Acid detergent fibre (ADF) and neutral detergent fibre (NDF) concentrations decreased from harvest 1 to 3, while dry-matter (DM) digestibility and D-value (% DM) were higher in 1st compared to 2nd harvest. Across the twenty year period, silage DM and water soluble carbohydrate concentrations increased, while ADF and NDF concentrations decreased. Crude protein concentration did not change over time. There was no significant improvement in silage digestibility. While silage intake potential for dairy cows increased by approximately 8% (from 88.8 to 96.1 g kg W^0.75, meant across all harvests), silage intake potential for beef cattle increased only within harvest 1. Despite overall increases in silage DM concentration, silage digestibility parameters did not show any significant improvement over the 20-year period, highlighting the need for a renewed focus on improving silage nutritive value.

中文翻译：

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1998 年至 2017 年北爱尔兰农场的青贮饲料成分和营养价值

青贮饲料是北爱尔兰 (NI) 饲养时提供给反刍家畜的主要保存草料。本研究涉及对数据集（n = 76,452 个样品），包括来自商业农场的青贮样品，由农业食品和生物科学研究所 (AFBI) 在 1998 年至 2017 年间进行分析。检查了收获次数（1、2 或 3）和年份的影响。收获 1-3 之间的大多数差异是显着的，尽管这些差异几乎没有生物学意义。青贮粗蛋白 (CP) 从第 1 次收获到第 3 次收获增加，而氨氮浓度在第 3 次收获中更高。酸性洗涤纤维 (ADF) 和中性洗涤纤维 (NDF) 的浓度从收获 1 到 3 下降，而与第二次收获相比，第 1 次的干物质 (DM) 消化率和 D 值 (% DM) 更高。在 20 年期间，青贮饲料 DM 和水溶性碳水化合物浓度增加，而 ADF 和 NDF 浓度下降。粗蛋白浓度不随时间变化。青贮饲料的消化率没有显着改善。虽然奶牛的青贮饲料摄入潜力增加了大约 8%（从 88.8 到 96.1 g kg W^0.75，意味着所有收获），肉牛的青贮饲料摄入潜力仅在收获 1 期间增加。尽管青贮饲料 DM 浓度总体增加，但青贮饲料消化率参数在 20 年期间没有显示任何显着改善，突出表明需要更新重点提高青贮饲料的营养价值。