Beck Matthew R, Zapalac Dakota, Chapman James D, Zanzalari K P, Holub Glenn A, Bascom Scott S, Engstrom Mark A, Reuter R Ryan, Foote Andrew P
Department of Animal & Food Sciences, Oklahoma State University, Stillwater, OK 74078, USA.
Phibro Animal Health, Teaneck, NJ 07666, USA.
Transl Anim Sci. 2022 Jan 17;6(1):txac010. doi: 10.1093/tas/txac010. eCollection 2022 Jan.
The objective of this experiment was to determine the effects of dietary vitamin D source on serum calcium (Ca), urinary Ca excretion, and milk production when fed in combination with a prepartum acidogenic negative dietary cation-anion difference (DCAD) diet. Nonlactating, pregnant multiparous cows ( = 15), balanced for breed (Holstein = 9 and Jersey = 6), and previous mature equivalent milk production, were assigned to one of three treatments (five cows/treatment), consisting of a control (PCH; positive DCAD, 8.9 mEq/100 g DM) and two negative DCAD diets (-15.4 mEq/100 g DM), one with vitamin D3 (cholecalciferol; NCH) and one with 25-hydroxyvitamin D3 (calcidiol; NCA; DSM nutritional products). The treatments were formulated to provide 1.95 mg/d of vitamin D and were fed 28 d prior to expected calving date. Delivery of vitamin D sources was accomplished by manufacture of a pellet and 2 kg of these pellets were individually fed simultaneously each day along with 2 kg of ground corn daily at 0800 hours. Negative DCAD treatments were formulated to provide 0.46 kg/d of Animate (Phibro Animal Health) and, if needed, additional Animate was top-dressed at each feeding to achieve a urine pH between 5.5 and 6.0 based on the previous day's urine pH. Close-up cows had ad libitum access to chopped bermudagrass ( L.) hay and hay intake was measured using SmartFeed Pro systems (C-Lock Inc.; Rapid City, SD). Prepartum urine and serum samples were collected weekly and serum was collected 36, 48, and 72 h post-calving. Prepartum dry matter intake (DMI) as a percent of body weight was not ( = 0.66) affected by treatments. Cows fed NCH and NCA had greater ( = 0.02) prepartum serum Ca than PCH and tended to have greater urinary Ca excretions ( = 0.10). Average postpartum serum Ca (mg/dL) was greater ( = 0.05) for cows fed NCH (8.8) compared with PCH (7.8), whereas NCA (8.4) was numerically intermediate and not ( 0.05) different from either of the other treatments. Postpartum DMI was not affected by treatment ( = 0.39). Daily milk yield (MY) (kg/d) was greatest ( < 0.01) for NCA (37.5) compared with the other treatments and NCH (34.1) was intermediate and greater than PCH (29.9). These results suggest that an acidogenic prepartum diet in combination with vitamin D was effective in maintaining peripartum serum Ca and the 25-hydroxy form of vitamin D improved MY compared with NCH in early lactation.
本实验的目的是确定在与产前产酸型负膳食阴阳离子差（DCAD）日粮配合饲喂时，日粮维生素D来源对血清钙（Ca）、尿钙排泄量和产奶量的影响。将非泌乳的经产怀孕母牛（n = 15头），按品种（荷斯坦牛9头和泽西牛6头）和之前的成熟当量产奶量进行均衡分组，分配到三种处理之一（每组5头牛），包括一个对照组（PCH；正DCAD，8.9 mEq/100 g DM）和两种负DCAD日粮（-15.4 mEq/100 g DM），一种添加维生素D3（胆钙化醇；NCH），另一种添加25-羟基维生素D3（骨化二醇；NCA；帝斯曼营养产品公司）。这些处理的配方设计为提供1.95 mg/d的维生素D，并在预计产犊日期前28天饲喂。维生素D源通过制成颗粒进行投喂，每天0800时，将2 kg这些颗粒与2 kg磨碎的玉米同时单独投喂给每头牛。负DCAD处理的配方设计为每天提供0.46 kg的活力源（菲布罗动物保健公司），如有需要，根据前一天的尿液pH值，在每次投喂时额外添加活力源，以使尿液pH值在5.5至6.0之间。围产前期母牛可自由采食切碎的百慕大草（Cynodon dactylon (L.) Pers.）干草，使用SmartFeed Pro系统（C-Lock公司；南达科他州拉皮德城）测量干草摄入量。产前每周采集尿液和血清样本，并在产后36、48和72小时采集血清。产前干物质摄入量（DMI）占体重的百分比不受处理影响（P = 0.66）。饲喂NCH和NCA的母牛产前血清钙水平高于PCH（P = 0.02），且尿钙排泄量有增加趋势（P = 0.10）。与PCH（7.8 mg/dL）相比，饲喂NCH的母牛产后平均血清钙水平更高（P = 0.05），为8.8 mg/dL，而NCA（数据显示为8.4 mg/dL）介于两者之间，与其他两种处理无显著差异（P > 0.05）。产后DMI不受处理影响（P = 0.39）。与其他处理相比，NCA的日产奶量（MY）最高（P < 0.01），为37.5 kg/d，NCH（34.1 kg/d）介于两者之间且高于PCH（29.9 kg/d）。这些结果表明，产酸型产前日粮与维生素D配合使用可有效维持围产期血清钙水平，且在泌乳早期，与NCH相比，25-羟基形式的维生素D可提高产奶量。
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