Short communication: Risk of subacute ruminal acidosis affects the feed sorting behavior and milk production of early lactation cows
Short communication: Risk of subacute ruminal acidosis affects the feed sorting behavior and milk production of early lactation cows
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DOI：
10.3168/jds.2018-15064
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发表时间：
2019-01-01
影响因子：
3.5
通讯作者：
DeVries, T. J.
中科院分区：
文献类型：
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作者：
Coon, R. E.;Duffield, T. F.;DeVries, T. J.
本研究的目的是确定是否发生亚急性瘤胃酸中毒的风险，作为潜在的影响饮食秸秆颗粒大小，影响饲料分选，反刍行为，泌乳早期奶牛的产奶量。产犊后，41头经产荷斯坦奶牛饲喂全混合日粮，其中9%的小麦秸秆（干物质基础）切碎（1）使用2.54 cm筛（短; n = 21）或（2）使用5.08 cm筛（长; n = 20）。在产犊后的前4周，24 h/d监测反刍行为（使用连接到项圈的数据记录器记录）和网胃pH值（使用无线遥测推注记录）。由于技术故障，对38头奶牛进行了分析（每种处理n = 19）。每隔3d采集全混合日粮和日粮样品，确定饲料分选。根据酸中毒指数，使用干物质摄入量标准化的曲线下面积数据（网胃pH < 5.8）创建，将奶牛分类为发生亚急性瘤胃酸中毒（SARA）的低（LR）或高（HR）风险。低风险奶牛的平均（6.3 vs. 6.1）、最小（6.0 vs. 5.7）和最大（6.7 vs. 6.5）网胃腔pH值高于高风险奶牛。低风险奶牛的曲线下面积值（1.5 vs. 49.4 pH x min/d）也不太严重，并且在网状瘤胃pH阈值5.8以下花费的时间较少（21.9 vs. 309.2 min/d）。虽然总产奶量不受SARA风险的影响，但LR奶牛比HR奶牛生产更多的4%脂肪校正牛奶（47.2与41.9 kg/d）和乳脂（2.1与1.8 kg/d）。检测到SARA风险类别x治疗相互作用，用于对饮食的所有部分进行分类;长期治疗的HR奶牛根据饮食中最长的颗粒进行分类，而相同治疗的LR奶牛没有对该部分进行分类，这表明SARA风险可以通过更平衡的物理有效纤维摄入量来减轻。短期治疗的高风险奶牛消耗的膳食颗粒最长，如预测的那样，并有利于物理有效的中颗粒和短颗粒。对于反刍行为，检测到SARA风险类别x给药相互作用;在长期给药期间，HR奶牛的反刍倾向于低于LR奶牛（432.3与493.2 min/d）。总体而言，这些结果表明，LR奶牛消耗了更均衡的饮食，而HR奶牛对饲料进行了更多的分类，特别是当饲喂含有长秸秆颗粒的饮食时，这可能导致反刍活动和乳脂产量以及脂肪校正牛奶减少。
The objective of this study was to determine if the risk of developing subacute ruminal acidosis, as potentially affected by dietary straw particle size, influenced the feed sorting, rumination behavior, and milk production of early lactation dairy cows. Upon calving, 41 multiparous Holstein cows were fed a total mixed ration with 9% wheat straw (dry matter basis) chopped (1) using a 2.54-cm screen (short; n = 21) or (2) using a 5.08-cm screen (long; n = 20). For the first 4 wk following calving, rumination behavior (recorded using data loggers attached to neck collars) and reticulorumen pH (recorded using wireless telemetry boluses) were monitored 24 h/d. Due to technical failures, analyses were conducted on 38 cows (n = 19 per treatment). Total mixed ration and orts samples were collected every 3 d to determine feed sorting. Based on an acidosis index, created using area under the curve data (reticulorumen pH < 5.8) normalized for dry matter intake, cows were categorized as either low (LR) or high (HR) risk for developing subacute ruminal acidosis (SARA). Low risk cows had higher mean (6.3 vs. 6.1), minimum (6.0 vs. 5.7), and maximum (6.7 vs. 6.5) reticulorumen pH than HR cows. Low risk cows also had less severe area under the curve values (1.5 vs. 49.4 pH x min/d) and spent less time below a reticulorumen pH threshold of 5.8 (21.9 vs. 309.2 min/d). Although total milk yield was unaffected by SARA risk, LR cows produced more 4% fat-corrected milk (47.2 vs. 41.9 kg/d) and milk fat (2.1 vs. 1.8 kg/d) than HR cows. A SARA risk category x treatment interaction was detected for sorting all fractions of the diet; HR cows on the long treatment sorted against the longest particles in the diet, whereas LR cows on the same treatment did not sort this fraction, suggesting that SARA risk may be mitigated by a more balanced intake of physically effective fiber. High risk cows on the short treatment consumed the longest dietary particles as predicted, and sorted in favor of the physically effective medium and short particles. A SARA risk category x treatment interaction was detected for rumination behavior; within the long treatment, HR cows tended to ruminate less than LR cows (432.3 vs. 493.2 min/d). Overall, these results suggest that LR cows consumed a more balanced diet, whereas HR cows sorted their feed more, particularly when fed the diet containing long straw particles, which may have led to reduced rumination activity and yield of milk fat and fat-corrected milk.