Department of Animal Breeding and Production, Warsaw University of Life Sciences - SGGW, Warsaw, Poland.
Área de Anatomía, Facultad de Veterinaria, University of the Republic, Montevideo, Uruguay.
J Anim Sci. 2018 Sep 7;96(9):3728-3737. doi: 10.1093/jas/sky241.
Although plasticity of growth rates is mainly associated with ectotherm species, it does occur in endotherms as well, but has not been documented systematically for many species. We compared the effect of 2 common types of feeding systems, differing in energetic value, on body size and gastrointestinal tract morphology in nutrias (Myocastor coypus). A total of 30 extensively (E) fed and 20 intensively (I) fed animals were used in the study. We noted significant effects of age, sex, and feeding regime on body weight and length, with 1-yr-old females attaining 3.7 ± 0.4 kg and 33.4 ± 1.5 cm on E and 4.9 ± 0.3 kg and 36.1 ± 2.3 cm on I. A significant treatment-sex interaction indicated that treatment had a greater effect on the length growth in males (1-yr-old males attaining 4.0 ± 0.2 kg and 34.7 ± 1.2 cm on E and 5.4 ± 0.4 kg and 41.0 ± 1.4 cm on I). The differences matched individual literature reports of free-ranging or intensively fed nutrias. The majority of gastrointestinal tract measurement results were only related to body weight, without additional effect of the diet regime, except for a higher small intestinal tissue weight on I (79 ± 14 g vs. 61 ± 7 g on E). In contrast, the wet content weight of the stomach, caecum, and the total gastrotinestinal tract was higher on E (196 ± 34 g vs. 164 ± 51 g on I). Overall, we observed strong influence of dietary regime on body development but not on digestive anatomy, indicating a distinct phenotypic flexibility in growth rates in nutrias.
尽管生长率的可塑性主要与变温动物物种有关，但它也确实存在于恒温动物中，只是尚未对许多物种进行系统记录。我们比较了两种常见的饲养系统对海狸鼠（Myocastor coypus）体型和胃肠道形态的影响，这两种系统在能量值上有所不同。研究中使用了 30 只广泛饲养（E）的和 20 只集约饲养（I）的动物。我们注意到年龄、性别和饲养方式对体重和体长有显著影响，1 岁雌性在 E 组中达到 3.7 ± 0.4 公斤和 33.4 ± 1.5 厘米，在 I 组中达到 4.9 ± 0.3 公斤和 36.1 ± 2.3 厘米。处理-性别交互作用显著，表明处理对雄性的体长生长影响更大（1 岁雄性在 E 组中达到 4.0 ± 0.2 公斤和 34.7 ± 1.2 厘米，在 I 组中达到 5.4 ± 0.4 公斤和 41.0 ± 1.4 厘米）。这些差异与自由放养或集约饲养的海狸鼠的个别文献报道相匹配。大多数胃肠道测量结果仅与体重相关，不受饮食方式的影响，除了 I 组小肠组织重量较高（79 ± 14 克比 E 组的 61 ± 7 克）。相比之下，E 组的胃、盲肠和整个胃肠道的湿重更高（196 ± 34 克比 I 组的 164 ± 51 克）。总体而言，我们观察到饮食方式对身体发育有强烈影响，但对消化解剖结构没有影响，这表明海狸鼠的生长率具有明显的表型灵活性。
