Neff A K, Buse K K, Carroll A L, Brown-Brandl T M, Kononoff P J
Department of Animal Science, University of Nebraska-Lincoln, Lincoln, NE 68503.
Department of Biological Systems Engineering, University of Nebraska-Lincoln, Lincoln 68583.
JDS Commun. 2025 Jun 18;6(5):665-668. doi: 10.3168/jdsc.2025-0774. eCollection 2025 Sep.
Methane (CH), carbon dioxide (CO), and oxygen (O) are the major gases produced by dairy cattle as a result of rumen fermentation and metabolism, and thus, their concentrations are frequently measured as a way of estimating heat production and energy metabolism. A well-utilized method of measuring gas consumption and production to estimate heat production is indirect calorimetry, which requires bags to retain the sampled gases until analysis. The objective of this study was to determine the ability of a polyvinyl fluoride gas bag (PF) and a multilayer fabrication gas bag containing an aluminum layer (NAP) to maintain respiratory gas composition in comparison to a polyethylene terephthalate bag (PET). For experiments 1 and 2, respiratory gases were collected from 6 multiparous, lactating Jersey cows using headbox-style indirect calorimeters. During experiment 1, PF and PET were used to sample respired gases of the headboxes for each cow. Experiment 2 used a similar design to compare NAP and PET. In both experiments, respired air was sampled into the gas bags for 5 h before being analyzed immediately to determine the concentrations of the gases. All bags were reanalyzed for gas concentrations at 24 and 72 h after sampling to determine the ability to maintain the concentration of gas over a 3-d period. In experiment 1, a tendency was observed for time by bag material interaction, as PET retained a consistent concentration of O (20.37% ± 0.020%) over the 72-h period, whereas the O concentration in PF increased from 20.37% to 20.47% ± 0.02%. Similarly for CO, PET maintained a consistent concentration of 0.653% ± 0.020% from hour 0 to 72, whereas PF significantly decreased from 0.65% to 0.55% ± 0.02%. No interactions between bag material and time occurred for CH across 72 h for PET and PF, averaging 0.0421% ± 0.005%, respectively. In experiment 2, comparing NAP and PET, no bag material, time, or bag material by time interactions were observed for O concentration, CO concentration, or CH concentration, averaging 20.37% ± 0.020% O, 0.648% ± 0.025% CO, and 0.0377% ± 0.0100% CH between treatments. Results indicate a significant difference in gas concentrations over time for PF relative to PET, and no difference was observed in gas concentrations for NAP in comparison to the PET bag. Thus, gas bag material type and time to gas analysis should be considered to effectively characterize respiratory gas composition.
甲烷（CH）、二氧化碳（CO）和氧气（O）是奶牛瘤胃发酵和新陈代谢产生的主要气体，因此，它们的浓度常被作为估算产热和能量代谢的一种方式进行测量。一种用于测量气体消耗和产生以估算产热的常用方法是间接量热法，该方法需要袋子来保存采集的气体直至进行分析。本研究的目的是确定聚氟乙烯气袋（PF）和含铝层的多层制造气袋（NAP）与聚对苯二甲酸乙二酯袋（PET）相比，维持呼吸气体成分的能力。在实验1和实验2中，使用头箱式间接量热仪从6头经产泌乳泽西奶牛收集呼吸气体。在实验1中，PF和PET用于采集每头奶牛头箱中的呼出气体。实验2采用类似设计比较NAP和PET。在两个实验中，呼出的空气被采集到气袋中5小时，然后立即进行分析以确定气体浓度。在采样后24小时和72小时对所有气袋重新分析气体浓度，以确定在3天时间内维持气体浓度的能力。在实验1中，观察到袋子材料与时间的交互作用存在一种趋势，因为PET在72小时内保持了一致的氧气浓度（20.37%±0.020%），而PF中的氧气浓度从20.37%增加到20.47%±0.02%。同样对于二氧化碳，PET从第0小时到72小时保持了0.653%±0.020%的一致浓度，而PF则从0.65%显著下降到0.55%±0.02%。在72小时内，PET和PF的甲烷在袋子材料和时间之间没有交互作用，平均分别为0.0421%±0.005%。在实验2中，比较NAP和PET，在氧气浓度、二氧化碳浓度或甲烷浓度方面，未观察到袋子材料、时间或袋子材料与时间的交互作用，各处理之间平均氧气浓度为20.37%±0.020%、二氧化碳浓度为0.648%±0.025%、甲烷浓度为0.0377%±0.0100%。结果表明，与PET相比，PF的气体浓度随时间有显著差异，而与PET袋相比，NAP的气体浓度没有差异。因此，应考虑气袋材料类型和气体分析时间，以有效地表征呼吸气体成分。
