Schüßler Dominik, Greven Hartmut
Department Biology, University of Düsseldorf, Universitätsstr. 1, Düsseldorf, Germany.
Zoo Biol. 2017 Dec;36(6):407-412. doi: 10.1002/zoo.21386. Epub 2017 Nov 14.
Giraffes are ruminants feeding on fresh browse and twigs in the wild, but in zoos, their diet is mainly based on alfalfa hay, grains, and pellets occasionally supplemented by twigs and foliage. These diets, which differ in composition and digestibility, affect the behavior of the animals, tooth wear patterns, and chewing efficiency. We quantified several parameters of the rumination process in ten zoo housed giraffes of different sexes and ages fed either with alfalfa hay, fresh browse, or a combination of both. Chewing during rumination was highly ritualized and specimens showed an even distribution of chewing directions during this process, which prevents uneven tooth wear and use of chewing muscles. During rumination of alfalfa hay, chewing cycles of the giraffes took on average 49 s and included 54 jaw movements compared to 37 s and 42 jaw movements during rumination of browse, respectively. Single jaw movements (measured as basic chewing rates) were on average significantly slower during rumination of alfalfa hay (alfalfa: 1.10 chews per second, browse: 1.17 chews per second) and intercycle times between two chewing cycles took significantly longer (alfalfa: 7.77 s, browse: 7.46 s). Our results clearly indicate that several rumination parameters are influenced by the type of diet.
长颈鹿是反刍动物，在野外以新鲜的嫩枝和细枝为食，但在动物园里，它们的饮食主要以苜蓿干草、谷物和颗粒饲料为主，偶尔辅以嫩枝和树叶。这些饮食在成分和消化率上有所不同，会影响动物的行为、牙齿磨损模式和咀嚼效率。我们对10只圈养在动物园里、不同性别和年龄的长颈鹿进行了反刍过程的几个参数的量化，这些长颈鹿分别喂食苜蓿干草、新鲜嫩枝或两者的组合。反刍时的咀嚼高度程式化，样本在这个过程中咀嚼方向分布均匀，这可以防止牙齿不均匀磨损和咀嚼肌肉的不均衡使用。在反刍苜蓿干草时，长颈鹿的咀嚼周期平均为49秒，包括54次颌部运动，而反刍嫩枝时分别为37秒和42次颌部运动。单次颌部运动（以基本咀嚼速率衡量）在反刍苜蓿干草时平均明显较慢（苜蓿：每秒1.10次咀嚼，嫩枝：每秒1.17次咀嚼），两个咀嚼周期之间的循环间隔时间明显更长（苜蓿：7.77秒，嫩枝：7.46秒）。我们的结果清楚地表明，几个反刍参数受饮食类型的影响。
