Department of Animal Sciences, Ohio Agricultural Research and Development Center, The Ohio State University, Columbus, OH 43210, USA.
J Dairy Sci. 2013 Jun;96(6):3845-56. doi: 10.3168/jds.2012-6100. Epub 2013 Apr 12.
Most available Jersey calf milk replacers (CMR) use edible lard as the primary fat source, which lacks medium-chain fatty acids (MCFA). However, Jersey cow milk consists of over 10% MCFA. The objective of this trial was to determine whether altering the fatty acid profile of CMR by increasing the amount of MCFA would alter liver lipid infiltration, liver gene expression, and blood metabolites when fed to Jersey calves. Fifty Jersey calves were fed 1 of 4 diets: pasteurized saleable whole milk (pSWM) from Jersey cows [27.9% crude protein (CP), 33.5% fat, dry matter (DM) basis]; CMR containing 100% of fat as edible lard (100:00; 29.3% CP, 29.1% fat, DM basis); CMR containing 20% of fat as coconut oil (CO; 80:20; 28.2% CP, 28.0% fat); or CMR containing 40% of fat as CO (60:40; 28.2% CP, 28.3% fat). Liquid diet DM intake averaged 0.523, 0.500, 0.498, and 0.512 kg/d for pSWM, 100:00, 80:20, and 60:40, respectively. Calves were fed their assigned liquid diet daily at 0600 and 1800 h from 2 d of age until 7 wk of age, and once daily until 8 wk of age. Calves were taken off trial at 9 wk of age. Calves had access to water and grain (23.8% CP, 2.71% fat, DM basis). Grain DM intake averaged 0.386, 0.439, 0.472, and 0.454 kg/d for pSWM, 100:00, 80:20, and 60:40, respectively. Liver biopsy cores were obtained from 15 calves at 42 d of age (pSWM, n=4; 100:00, n=4; 80:20, n=3; 60:40, n=4) and from 4 baseline calves <2d of age. Liver biopsy cores were used for histological appraisal of lipid infiltration and gene expression analyses of short-, medium-, and long- chain acyl-coenzyme A dehydrogenases, sterol regulatory element binding transcription factor 1, acetyl coenzyme A carboxylase, and fatty acid synthase. Lipid infiltration and expression of selected genes were not different among diets. After an overnight fast, weekly blood samples were taken immediately before feeding at 0600 h via jugular venipuncture in all calves. Serum and plasma obtained from blood samples were used in the analyses of total protein, glucose, triglycerides, nonesterified fatty acids, and plasma urea nitrogen (PUN). Nonesterified fatty acids and PUN were the only blood metabolites affected solely by diet. Nonesterified fatty acids decreased in a linear manner with increased dietary CO inclusion. Calves fed pSWM had higher PUN than calves fed 80:20. In this trial, altering the fatty acid profile of CMR with the addition of medium-chain fatty acids from CO had minimal effects on liver lipid infiltration, liver gene expression, and blood metabolites when fed to Jersey calves.
大多数市售的泽西牛代乳粉（CMR）使用可食用猪油作为主要脂肪来源，但缺乏中链脂肪酸（MCFA）。然而，泽西牛奶中含有超过 10%的 MCFA。本试验旨在确定通过增加 MCFA 的量来改变 CMR 的脂肪酸谱，是否会改变泽西小牛的肝脏脂质浸润、肝脏基因表达和血液代谢物。50 头泽西小牛分别饲喂 4 种日粮中的 1 种：泽西牛的巴氏杀菌销售全脂奶（pSWM）[27.9%粗蛋白（CP），33.5%脂肪，干物质（DM）基础]；100%脂肪为食用猪油的 CMR（100:00；29.3% CP，29.1%脂肪，DM 基础）；20%脂肪为椰子油（CO）的 CMR（80:20；28.2% CP，28.0%脂肪）；40%脂肪为 CO 的 CMR（60:40；28.2% CP，28.3%脂肪）。液体日粮 DM 摄入量分别为 pSWM、100:00、80:20 和 60:40 的 0.523、0.500、0.498 和 0.512kg/d。从 2 日龄开始，小牛每天在 0600 和 1800 时分别饲喂其分配的液体日粮，直至 7 周龄，然后每天饲喂一次，直至 8 周龄。小牛在 9 周龄时停止试验。小牛可以自由饮水和采食谷物（23.8% CP，2.71%脂肪，DM 基础）。pSWM、100:00、80:20 和 60:40 的谷物 DM 摄入量分别为 0.386、0.439、0.472 和 0.454kg/d。42 日龄时（pSWM，n=4；100:00，n=4；80:20，n=3；60:40，n=4）和 4 头小于 2 日龄的基线小牛各取 15 头小牛的肝活检芯，用于评估脂质浸润的组织学评估和短链、中链和长链酰基辅酶 A 脱氢酶、固醇调节元件结合转录因子 1、乙酰辅酶 A 羧化酶和脂肪酸合酶的基因表达分析。在日粮之间，脂质浸润和选定基因的表达没有差异。所有小牛在禁食过夜后，每周在 0600 时通过颈静脉穿刺立即在饲喂前采集血液样本。从血液样本中获得血清和血浆，用于分析总蛋白、葡萄糖、甘油三酯、非酯化脂肪酸和血浆尿素氮（PUN）。非酯化脂肪酸和 PUN 是仅受饮食影响的两种血液代谢物。非酯化脂肪酸随着日粮中 CO 含量的增加而呈线性下降。饲喂 pSWM 的小牛的 PUN 高于饲喂 80:20 的小牛。在这项试验中，通过添加中链脂肪酸 CO 来改变 CMR 的脂肪酸谱，当饲喂泽西小牛时，对肝脏脂质浸润、肝脏基因表达和血液代谢物的影响很小。
