Vargas-Rodriguez C F, Yuan K, Titgemeyer E C, Mamedova L K, Griswold K E, Bradford B J
Department of Animal Sciences and Industry, Kansas State University, Manhattan 66506.
Kemin Industries, Des Moines, IA 50317.
J Dairy Sci. 2014;97(6):3815-21. doi: 10.3168/jds.2013-7767. Epub 2014 Apr 14.
Chromium (Cr) feeding in early lactation increased milk production in some studies, but responses to dietary Cr during peak lactation have not been evaluated. Furthermore, interactions of essential amino acids (AA) and Cr have not been explored. Our objective was to evaluate responses to CrPr (KemTRACE chromium propionate 0.04%, Kemin Industries Inc., Des Moines, IA) and rumen-protected Lys (LysiPEARL, Kemin Industries Inc.) and Met (MetiPEARL, Kemin Industries Inc.) and their interaction in peak-lactation cows. Forty-eight individually fed Holstein cows (21 primiparous, 27 multiparous, 38 ± 15 d in milk) were stratified by calving date in 12 blocks and randomly assigned to 1 of 4 treatments within block. Treatments were control, CrPr (8 mg/d of Cr), RPLM (10 g/d of Lys and 5 g/d of Met, intestinally available), or CrPr plus RPLM. Treatments were premixed with ground corn and top-dressed at 200 g/d for 35 d. Diets consisted of corn silage, alfalfa hay, and concentrates, providing approximately 17% crude protein, 31% neutral detergent fiber, and 40% nonfiber carbohydrates. Dry matter intake (DMI) significantly increased with the inclusion of CrPr (22.2 vs. 20.8 ± 0.67 kg/d), and energy-corrected milk (ECM) yield tended to increase. In addition, CrPr increased milk protein yield and tended to increase DMI in primiparous cows but not in multiparous cows. A CrPr×week interaction was detected for milk lactose content, which was increased by CrPr during wk 1 only (4.99 vs. 4.88 ± 0.036%). As a proportion of plasma AA, lysine increased and methionine tended to increase in response to RPLM, but the inclusion of RPLM decreased N efficiency (milk protein N:N intake). Digestible energy intake, gross energy digestibility, and energy balance were not affected by treatments. We observed no treatment effects on feed efficiency or changes in body weight or body condition score. In summary, feeding CrPr increased DMI and tended to increase ECM in cows fed for 5 wk near peak lactation, with primiparous cows showing greater responses in DMI and milk protein yield than multiparous cows.
在一些研究中，泌乳早期补饲铬（Cr）可提高产奶量，但泌乳高峰期日粮中添加铬的效果尚未得到评估。此外，必需氨基酸（AA）与铬之间的相互作用也未被探究。我们的目标是评估泌乳高峰期奶牛对丙酸铬（KemTRACE丙酸铬0.04%，Kemin Industries Inc.，得梅因，爱荷华州）、瘤胃保护性赖氨酸（LysiPEARL，Kemin Industries Inc.）和蛋氨酸（MetiPEARL，Kemin Industries Inc.）的反应及其相互作用。48头个体饲养的荷斯坦奶牛（21头初产牛，27头经产牛，产奶38±15天）按产犊日期分为12个区组，并在每个区组内随机分配到4种处理中的1种。处理方式为对照组、丙酸铬（8毫克/天的铬）、瘤胃保护性赖氨酸和蛋氨酸（10克/天的赖氨酸和5克/天的蛋氨酸，肠道可利用），或丙酸铬加瘤胃保护性赖氨酸和蛋氨酸。处理组与粉碎玉米预混，每天以200克的量进行顶饲，持续35天。日粮由玉米青贮、苜蓿干草和精料组成，提供约17%的粗蛋白、31%的中性洗涤纤维和40%的非纤维碳水化合物。添加丙酸铬后干物质采食量（DMI）显著增加（22.2对20.8±0.67千克/天），能量校正乳（ECM）产量有增加趋势。此外，丙酸铬提高了初产牛的乳蛋白产量，并使初产牛的DMI有增加趋势，但经产牛没有。在乳乳糖含量方面检测到丙酸铬×周的交互作用，仅在第1周丙酸铬使乳乳糖含量增加（4.99对4.88±0.036%）。作为血浆氨基酸的一部分，瘤胃保护性赖氨酸和蛋氨酸使赖氨酸增加，蛋氨酸有增加趋势，但添加瘤胃保护性赖氨酸和蛋氨酸降低了氮效率（乳蛋白氮：氮摄入量）。可消化能量摄入量、总能消化率和能量平衡不受处理影响。我们未观察到处理对饲料效率或体重及体况评分变化有影响。总之，在泌乳高峰期附近给奶牛补饲5周，添加丙酸铬可增加DMI并使ECM有增加趋势，初产牛在DMI和乳蛋白产量方面的反应比经产牛更大。
