Regenerative Bioscience Center, University of Georgia, Athens, GA, USA; Department of Animal and Dairy Science, College of Agricultural and Environmental Sciences, University of Georgia, Athens, GA, USA; Laboratory of Functional Anatomy, Faculty of Agriculture, Kyushu University, Fukuoka, Japan.
Faculty of Agriculture and Life Science, Hirosaki University, Hirosaki, Japan.
Poult Sci. 2021 Jun;100(6):101113. doi: 10.1016/j.psj.2021.101113. Epub 2021 Mar 11.
Chickens have been reported to have a low taste bud count and thus low taste acuity. However, more recent studies indicate that the earlier reported count of chicken taste buds may have been significantly underestimated. To answer the question of whether the taste sensing system in broiler chickens evolved during the breeding selection over the past decades, we compared the taste sensitivity to bitter and taste buds between a meat-type control strain - the 1955 Athens Canadian Random Bred (ACRB), and a modern high-yielding broiler strain - the 2012 Cobb 500. The behavioral tests showed that the ACRB did not avoid bitter taste solutions of quinine hydrochloride (QHCl) at the examined concentrations (0.5, 1, 2, and 4 mM) (P > 0.05), while the Cobb 500 significantly avoided both the 2 mM and 4 mM QHCl solutions (P < 0.01). The labeling of chicken taste buds using the molecular marker Vimentin revealed that Cobb 500 chickens had a slightly higher number (P < 0.1), but lower density of taste bud clusters in the palate (P < 0.01) and the base of the oral cavity (P < 0.05) compared to the ACRB. We also found that a single amino acid change occurred in the bitter taste receptor T2R7. However, the functional analyses using HEK293T cells transiently expressing T2R7 revealed that the functions of T2R7 were comparable between the two strains. Taken together, our results demonstrated that taste sensitivities could be affected by the selection of the broiler chickens. The modern high-yielding broilers, which have massive feed intake and appetite, had a higher sensitivity to bitter taste stimuli than the meat-type chicken strain which was established decades ago. This evolvement of taste sensitivities may be associated with the alterations of an upper level of taste system, rather than the peripheral taste system, including distribution of taste buds and functions of taste receptors.
据报道，鸡的味蕾数量较少，因此味觉敏锐度较低。然而，最近的研究表明，早期报道的鸡味蕾数量可能被严重低估。为了回答在过去几十年的选育过程中，肉鸡的味觉感知系统是否进化的问题，我们比较了肉用型对照品系——1955 年雅典加拿大随机品系（ACRB）和现代高产品系——2012 年科布 500 对苦味和味蕾的敏感性。行为测试表明，在检测浓度（0.5、1、2 和 4 mM）下，ACRB 并没有回避盐酸奎宁（QHCl）的苦味溶液（P > 0.05），而科布 500 则显著回避了 2 mM 和 4 mM 的 QHCl 溶液（P < 0.01）。使用分子标记物波形蛋白对鸡味蕾进行标记显示，与 ACRB 相比，科布 500 鸡的味蕾数量略有增加（P < 0.1），但在 palate（P < 0.01）和口腔基底（P < 0.05）的味蕾簇密度较低。我们还发现苦味受体 T2R7 发生了单个氨基酸变化。然而，使用瞬时表达 T2R7 的 HEK293T 细胞进行的功能分析表明，两种品系的 T2R7 功能相当。总之，我们的研究结果表明，味觉敏感性可能受到肉鸡选育的影响。与几十年前建立的肉用型鸡品系相比，现代高产品系肉鸡具有更大的饲料摄入量和食欲，对苦味刺激的敏感性更高。这种味觉敏感性的进化可能与味觉系统的高层改变有关，而不是与味觉感受器的味觉感受器分布和功能有关。
