Department of Biology, Federal University of Lavras, MG, Brazil.
Department of Animal Science, Federal University of Lavras, MG, Brazil.
J Therm Biol. 2021 Apr;97:102897. doi: 10.1016/j.jtherbio.2021.102897. Epub 2021 Feb 26.
The objective of this study was to evaluate the effect of heat stress on meta-taxonomic and metabolic profiles of prokaryotes in beef cattle rumen. Six pure-breed Nellore heifers with ruminal cannulas were used in the study. Six treatments were tested in a 6 × 6 Latin Square with six periods of 21days. The treatments were evaluated in a 2 × 2 + 2 factorial arrangement, consisting of 4 combinations: two temperatures conditions (thermoneutral, TN: 24 °C; and heat stress, HS: 34 °C) and two dietary energy concentration [low-energy (37% non-fibrous carbohydrates - NFC, 12 Mcal of metabolizable energy per kg of dry matter) or high-energy concentration (50.5% NFC, 18.49 Mcal of metabolizable energy per kg of dry matter)] plus two additional treatments with animals maintained in TN conditions but with your intake restricted (TN-RI) to the same of the heifers in HS with the two dietary energy concentration. The meta-genome was sequenced by MiSeq Sequencing System platform, and the DNA sequences were analysed using Geneious 10.2.3 software. The metabolic profile was evaluated by liquid and gas chromatography. Animals under HS presented lower (P = 0.04) prokaryote richness than animals under TN conditions. The genera Flavonifractor (1.4%), Treponema (0.6%) and Ruminococcus (0.9%) showed the lowest (P < 0.04) and Carnobacterium (7.7%) the highest (P = 0.02) relative abundance when the animals were submitted to HS, in relation to animals in TN. A total of 49 different metabolites were identified in the ruminal samples. The concentration of isobutyric acid (4.32 mM) was highest in bovine rumen under HS conditions. Heat stress influenced the microbiota and concentration of some organic acids in beef cattle rumen. There was a reduction in the richness of rumen in cattle under heat stress, but the diversity of prokaryotes was not affected.
本研究旨在评估热应激对肉牛瘤胃中原核生物的分类群和代谢特征的影响。使用 6 头带有瘤胃套管的纯种内罗尔小母牛进行研究。在 6×6 拉丁方试验中测试了 6 种处理方法，每个试验期为 21 天。处理方法以 2×2+2 析因设计进行评估，包括 4 种组合：两种温度条件（常温，TN：24°C；热应激，HS：34°C）和两种日粮能量浓度[低能（37%非纤维性碳水化合物-NFC，每公斤干物质 12 兆卡代谢能）或高能浓度（50.5%NFC，每公斤干物质 18.49 兆卡代谢能）]，外加两种额外的处理方法，即将动物保持在 TN 条件下，但将采食量限制在 HS 条件下两种日粮能量浓度下的小母牛相同（TN-RI）。通过 MiSeq 测序系统平台对元基因组进行测序，并使用 Geneious 10.2.3 软件分析 DNA 序列。通过液相和气相色谱法评估代谢谱。HS 下的动物表现出较低的（P=0.04）原核生物丰富度，而 TN 条件下的动物则较高。Flavonifractor（1.4%）、Treponema（0.6%）和 Ruminococcus（0.9%）属的相对丰度最低（P<0.04），而 Carnobacterium（7.7%）的相对丰度最高（P=0.02），当动物处于 HS 时，与 TN 下的动物相比。在瘤胃液样品中鉴定出 49 种不同的代谢物。HS 条件下牛瘤胃中异丁酸（4.32mM）的浓度最高。热应激影响肉牛瘤胃中的微生物群和一些有机酸的浓度。热应激下牛瘤胃的丰富度降低，但原核生物的多样性不受影响。
