摘要
The objective of the study was to evaluate the use of n-alkanes to estimate DM intake and digestibility by beef cattle. Six steers were blocked (3 blocks, 2 animals/block) according to the body weight (27919 kg) and randomly allotted within blocks to two diets (3 steers/diet). A second trial was conducted with the same animals (32118 kg) after 36 days (d), using a switch back design. The diets consisted of two types of chopped sun-cured hay, alfalfa (Medicago sativa L) hay, or fescue (Festuca arundinacea Schreb) and alfalfa mixture, which were fed in equal amounts to steers. Animals were dosed with and alkanes, employing an intra-ruminal controlled-release device at the beginning of each trial. Hay intake per animal was measured from d 6 to 12 and sub samples were taken for chemical analysis. Rectal samples of feces were taken from each animal once/daily from d 8 to 14, freeze dried, and ground prior to alkane analysis. Alkanes were extracted from ground hay and feces. Feed intake was calculated from the dose rate of alkane and, the herbage and fecal concentrations of adjacent odd ( or ) and even () chain length alkanes. Crude Protein, NDF, ADF, ash concentrations and In vitro dry matter digestibility (IVDMD) were 17.7, 42.2, 28.4, 7.9 and 71.7 for alfalfa, and 12.4, 56.5, 30.4, 6.9 and 69.1% for fescue/alfalfa mixture, respectively. For both diets, intake estimated from : ratio was not different from the measured intake, but intake estimated from : ratio was lower (p<0.05), than the measured intake for both diets. The average estimated forage intake from : ratio was 4.86 and 0.69% below than the measured intake for alfalfa and, fescue/alfalfa mixed diets, respectively. The respective estimates with : ratio were 9.59 and 11.33% below than the measured intake. According to these results, alkane : ratio is better than alkane : ratio for the estimation of intake by beef steers.
摘要译文
该研究的目的是评估使用正构烷烃估算肉牛的DM摄入量和消化率。六个阉牛被封锁（3个街区，2只动物/块）根据体重（27919公斤）并随机分配到两个饮食（3个阉牛/饮食）。使用回转设计，在36天（d）后对相同的动物（32118kg）进行第二次试验。饮食包括两种切碎的晒干干草，紫花苜蓿（Medicago sativa L）干草，或羊茅（Festuca arundinacea Schreb）和苜蓿混合物，它们以相同的量喂养。给动物服用烷烃，在每次试验开始时使用瘤内控制释放装置。从第6天到第12天测量每只动物的干草摄入量，并且取样子进行化学分析。从第8天到第14天每只动物从每只动物取直肠粪便样品，冷冻干燥，并在烷烃分析之前研磨。从地面干草和粪便中提取烷烃。根据烷烃的剂量率和相邻的奇数（或）和偶数（）链长烷烃的牧草和粪便浓度计算采食量。粗蛋白，NDF，ADF，苜蓿的灰分浓度和体外干物质消化率（IVDMD）分别为17.7,42.2,28.4,7.9和71.7，对于羊茅/苜蓿混合物分别为12.4,56.5,30.4,6.9和69.1％。对于这两种饮食，摄入量估计为：比例与测量的摄入量没有差异，但摄入量估计来自：比率低于两种饮食的测量摄入量（p 0.05）。平均估计饲草摄入量：比例分别比苜蓿和羊茅/苜蓿混合饲料的测量摄入量低4.86和0.69％。相应的估计值：比率比测量的摄入量低9.59和11.33％。根据这些结果，烷烃：比率优于烷烃：牛肉阉牛的摄入量估算比率。
Premaratne, S.; Fontenot, J.P.; Shanklin, R.K.;. Use of N-alkanes to Estimate Intake and Digestibility by Beef Steers[J]. Asian-Australasian Journal of Animal Sciences, 2005,18(11): 1564-1568