Sandoval-Lozano Edwin, Barragán Iang S Rondón, Sandoval-Lozano Andrés, Castañeda-Serrano Román David
Research Group in Livestock Agroforestry Systems, Faculty of Veterinary Medicine and Zootechnics, Department of Animal Production, University of Tolima, Ibagué 730006, Colombia.
Research Group in Immunobiology and Pathogenesis, Faculty of Veterinary Medicine and Zootechnics, Department of Animal Health, University of Tolima, Ibagué 730006, Colombia.
Vet Sci. 2025 Aug 24;12(9):801. doi: 10.3390/vetsci12090801.
Small ruminant production is increasingly affected by heat stress, with recent heat waves highlighting growing economic and welfare-related challenges. Chronic exposure to elevated temperatures disrupts thermoregulation, reduces feed intake, slows growth, compromises meat quality, and increases mortality. This study evaluated the effects of chromium-yeast supplementation at different doses and timepoints on physiological and molecular stress biomarkers in heat-stressed lambs. Forty-eight clinically healthy 6-month-old Katahdin lambs (average weight 20 ± 2.9 kg) were assigned to a 2 × 4 factorial design, with two ambient temperature conditions (heat stress [HS] and thermoneutral [TN]) and four levels of dietary Cr-yeast (0, 0.2, 0.4, and 0.8 mg/kg of dry matter intake). Lambs were housed individually in pens (1.2 × 2.5 m), with ad libitum access to water, and fed a 50:50 corn silage and concentrate diet (excluding mineral premix) twice daily. Blood samples were collected at days 0, 30, and 60 to evaluate plasma cortisol and the expression of and . Chromium bioavailability was assessed by blood levels using absorption chromatography, and glucose clearance was measured at the end of the experiment. Significant reductions in cortisol and expression were observed after 30 days of Cr-yeast supplementation under HS conditions ( < 0.05), particularly at the highest dose. For , a significant reduction was observed at the highest dose on day 30 under HS ( < 0.05). These effects were not sustained on day 60 ( > 0.05). No significant differences were detected under TN conditions ( > 0.05). These findings suggest that Cr-yeast may offer short-term physiological and cellular protection against chronic heat stress in lambs.
小型反刍动物生产日益受到热应激的影响，近期的热浪凸显了与经济和福利相关的挑战日益增加。长期暴露于高温会扰乱体温调节，减少采食量，减缓生长速度，损害肉质，并增加死亡率。本研究评估了在不同剂量和时间点补充酵母铬对热应激羔羊生理和分子应激生物标志物的影响。将48只临床健康的6月龄卡他丁羔羊（平均体重20±2.9千克）分配到一个2×4析因设计中，有两种环境温度条件（热应激[HS]和热中性[TN]）以及四个日粮酵母铬水平（0、0.2、0.4和0.8毫克/千克干物质采食量）。羔羊单独饲养在围栏（1.2×2.5米）中，自由饮水，每天喂两次50:50的玉米青贮和精料日粮（不包括矿物质预混料）。在第0、30和60天采集血样，以评估血浆皮质醇以及[具体基因名称1]和[具体基因名称2]的表达。使用吸收色谱法通过血液水平评估铬的生物利用度，并在实验结束时测量葡萄糖清除率。在热应激条件下，补充酵母铬30天后观察到皮质醇和[具体基因名称1]表达显著降低（P<0.05），特别是在最高剂量时。对于[具体基因名称2]，在热应激条件下第30天最高剂量时观察到显著降低（P<0.05）。这些影响在第60天未持续（P>0.05）。在热中性条件下未检测到显著差异（P>0.05）。这些发现表明，酵母铬可能为羔羊慢性热应激提供短期生理和细胞保护。
