Pickett Autumn T, Cooke Reinaldo F, Mackey Shea J, Prado Mykael B do, Gouvêa Vinicius N
Department of Animal Science - Texas A&M University, College Station, TX 77843, USA.
Texas A&M AgriLife Research and Extension Center, Amarillo, TX 79106, USA.
J Anim Sci. 2025 Jan 4;103. doi: 10.1093/jas/skaf311.
This experiment evaluated feed intake, physiological reactions, and ruminal parameters in beef cattle receiving or not receiving a lipopolysaccharide (LPS) challenge. Ten ruminally-cannulated Angus steers [590 ± 16 kg of body weight (BW)] were housed in individual pens on day -7, ranked by BW, and allocated to 1 of 2 treatments administered intravenously on day 0: 1) 0.5 μg/kg of BW of bacterial LPS (Escherichia coli 0111:B4) diluted in 5 mL of 0.9% sterile saline, or 2) 5 mL of 0.9% physiological saline (CON). Steers had free-choice access to wheat hay, water, and a commercial vitamin + mineral mix (days -7 to 7). Hay dry matter intake (DMI) was evaluated daily from days -5 to 7. Prior to treatment administration on day 0 (hour 0), polyester bags containing 4 g of ground dietary hay (DM basis) were immersed into the rumen of each steer, and incubated for 0, 4, 8, 12, 24, 36, 48, 60, and 72 h for dry matter (DM) and neutral detergent fiber (NDF) degradability evaluation. Steers were also intra-ruminally pulse-dosed with 5 g of Co-EDTA and with Cr-EDTA (0.1 g/kg of BW) prior to treatment administration. Rumen fluid samples were collected at 0, 2, 4, 6, 8, 12, 16, 24, 36, and 48 h, and blood samples were collected at -2, 0, 2, 4, 6, 8, 12, 18, 24, 36, 48, 60, 72, 96, 120, and 144 h relative treatment administration. Values obtained before treatment administration were used as covariates within each respective analysis. Steers receiving LPS had less (P ≤ 0.05) hay DMI on days 0 and 1, less (P < 0.01) rumen liquid volume and dilution rate, and less (P < 0.01) ruminal effective degradability of DM and NDF compared with CON. Steers receiving LPS had greater (P ≤ 0.05) plasma haptoglobin concentration from 18 to 144 h, greater (P ≤ 0.04) plasma cortisol concentration from 2 to 12 h, and less (P ≤ 0.04) total plasma Cr concentration from 2 to 18 h compared with CON. Steers receiving LPS had less (P ≤ 0.03) mean concentrations of acetate, butyrate, valerate, and total volatile fatty acids (VFA) in the rumen fluid compared with CON. Steers receiving LPS had less (P ≤ 0.05) mean total bacterial load in the ruminal fluid, and less mean prevalence of the phyla Spirochaetes and Fibrobacteres and the genera Treponema compared with CON. Results from this experiment suggest that LPS administration elicited host-microbiome endocrine interactions that impaired feed degradability and VFA production in the rumen, particularly a reduction in total bacterial load, which may have contributed to a 48-h decrease in hay DMI.
本实验评估了接受或未接受脂多糖（LPS）刺激的肉牛的采食量、生理反应和瘤胃参数。10头安装了瘤胃瘘管的安格斯阉牛[体重（BW）590±16千克]于第-7天被安置在个体栏舍中，按体重排序，并在第0天静脉注射两种处理之一：1）将0.5微克/千克体重的细菌LPS（大肠杆菌0111:B4）稀释于5毫升0.9%无菌盐水中；2）5毫升0.9%生理盐水（对照组）。阉牛在第-7至7天可自由采食小麦干草、饮水和一种商业维生素+矿物质混合物。从第-5至7天每天评估干草干物质采食量（DMI）。在第0天（0小时）处理给药前，将装有4克磨碎的日粮干草（以干物质计）的聚酯袋浸入每头阉牛的瘤胃中，并分别培养0、4、8、12、24、36、48、60和72小时，以评估干物质（DM）和中性洗涤纤维（NDF）的降解率。在处理给药前，还向阉牛瘤胃内脉冲投喂5克乙二胺四乙酸钴和乙二胺四乙酸铬（0.1克/千克体重）。在0、2、4、6、8、12、16、24、36和48小时采集瘤胃液样本，在处理给药后-2、0、2、4、6、8、12、18、24、36、48、60、72、96、120和144小时采集血样。处理给药前获得的值在各自分析中用作协变量。与对照组相比，接受LPS的阉牛在第0天和第1天的干草DMI较低（P≤0.05），瘤胃液体积和稀释率较低（P<0.01），瘤胃中DM和NDF的有效降解率较低（P<0.01）。与对照组相比，接受LPS的阉牛在18至144小时血浆触珠蛋白浓度较高（P≤0.05），在2至12小时血浆皮质醇浓度较高（P≤0.04），在2至18小时血浆总铬浓度较低（P≤0.04）。与对照组相比，接受LPS的阉牛瘤胃液中乙酸、丁酸、戊酸和总挥发性脂肪酸（VFA）的平均浓度较低（P≤0.03）。与对照组相比，接受LPS的阉牛瘤胃液中的平均总细菌载量较低（P≤0.05），螺旋体门、纤维杆菌门以及密螺旋体属的平均丰度较低。本实验结果表明，给予LPS引发了宿主-微生物群内分泌相互作用，损害了瘤胃中的饲料降解率和VFA生成，尤其是总细菌载量的降低，这可能导致干草DMI在48小时内下降。
