This study was conducted to determine the fecal recovery rate of n-alkanes and compare the precision and accuracy of the n-alkane technique and the conventional total fecal collection method in estimating the apparent nutrient digestibility of mixed hay diets fed to horses. Six castrated male adult horses (361 ± 12 kg body weight) were fed diets composed of different proportions of Tifton 85 bermudagrass (Cynodon dactylon) hay and alfalfa (Medicago sativa) hay in a 6 × 6 Latin square design. Treatments were as follows: T₁₀₀, 100% Tifton hay; T₈₀, 80% Tifton hay and 20% alfalfa hay; T₆₀, 60% Tifton hay and 40% alfalfa hay; T₄₀, 40% Tifton hay and 60% alfalfa hay; T₂₀, 20% Tifton hay and 80% alfalfa hay; and T₀, 100% alfalfa hay. The n-alkane detected at the greatest (P < 0.05) mean concentration in feed was n-hexatriacontane (C₃₆H₇₄), followed by n-hexacosane (C₂₆H₅₄), n-heptacosane (C₂₇H₅₆), n-nonacosane (C₂₉H₆₀), n-hentriacontane (C₃₁H₆₄), n-tritriacontane (C₃₃H₆₈), and n-pentatriacontane (C₃₅H₇₂). A strong correlation (r = 0.91, P < 0.001) was found between carbon chain length and fecal recovery. The n-Hentriacontane, n-tritriacontane, n-pentatriacontane, and n-hexatriacontane had the greatest fecal recovery (mean = 0.91, P < 0.05) and were therefore used to estimate nutrient digestibility. None of the n-alkanes provided consistent results. Fecal recovery was incomplete, and fecal recovery rates above 100% were obtained regardless of the proportion of Tifton and alfalfa hay in diets. Dry matter, crude protein, neutral detergent fiber, acid detergent fiber, and mineral matter digestibility estimated using n-alkanes differed (P < 0.05) from digestibility values obtained by the reference method (total fecal collection). The simplest explanation for these results would be that horses preferred one type of hay over the other and had an uneven intake of each diet. Because Tifton and alfalfa hay differ greatly in composition, their uneven intake makes estimation of nutrient digestibility by fecal recovery of n-alkanes unreliable. Even after correction for fecal recovery, n-alkanes were inaccurate markers of nutrient digestibility.

进行这项研究来确定正构烷烃的粪便回收率，并比较正构烷烃技术和常规总粪便收集方法在估计饲喂马匹的混合干草日粮的表观养分消化率方面的准确性和准确性。六只cast割的成年雄性马（体重361±12公斤）以6×6拉丁方形设计喂养，这些饲料由不同比例的Tifton 85百慕大草（Cynodon dactylon）干草和苜蓿（Medicago sativa）干草组成。处理如下：T ₁₀₀，100％蒂夫顿干草; Ť ₈₀，80％蒂夫顿干草和20％苜蓿干草; T _60，60％Tifton干草和40％苜蓿干草；T ₄₀，40％的提夫顿干草和60％的苜蓿干草；T _20，20％的蒂夫顿干草和80％的苜蓿干草；T _0为100％苜蓿干草。的正烷烃在最大的（检测到的P <0.05）在进料平均浓度为N-三十六烷（C ₃₆ H ^ ₇₄），其次是正二十六烷（C ₂₆ H ^ ₅₄），正二十七烷（C ₂₇ H ^ ₅₆），正壬二十烷（C ₂₉ H ₆₀），正三_二十烷（C ₃₁ H ₆₄），正包括三金刚烷（C ₃₃ H ₆₈）和正戊烷（C ₃₅ H ₇₂）。发现碳链长度和粪便恢复之间有很强的相关性（r  = 0.91，P <0.001）。的正三十一烷，正-三十三烷，正pentatriacontane，和N-三十六烷具有最大的粪便回收（平均值= 0.91，P <0.05），并因此被用来估计营养物质的消化率。在没有正烷烃提供一致的结果。粪便恢复不完全，无论日粮中蒂夫顿草和苜蓿干草的比例如何，粪便恢复率均超过100％。使用正构烷烃估算的干物质，粗蛋白，中性洗涤剂纤维，酸性洗涤剂纤维和矿物质的消化率与通过参考方法获得的消化率值（粪便总量）不同（P <0.05）。对于这些结果的最简单的解释是，马比另一种马更喜欢一种干草，并且每种饮食的摄入量均不均衡。由于Tifton和苜蓿干草的成分差异很大，因此它们的摄入量不均衡，从而通过粪便中n的回收来估算营养物质的消化率。-烷烃不可靠。即使在校正粪便恢复后，正构烷烃也不是营养物消化率的准确标志。