Institute of Animal Nutrition, Friedrich-Loeffler-Institute (FLI), Federal Research Institute for Animal Health, Braunschweig, Germany.
Arch Anim Nutr. 2011 Feb;65(1):55-73. doi: 10.1080/1745039x.2010.520408.
The aim of the present dose response study was to examine the long-term effects of increasing the amounts of rare earth elements (REE) in the diet on growth and slaughtering performance of fattening bulls. A total of 48 bulls of German Holstein with an average initial live weight (LW) of 119 + 13 kg were divided into four dietary treatment groups (n = 12): a control group and three REE-treated groups, which were fed a supplement of 100, 200 and 300 mg REE-citrate per kg dry matter (DM) containing mainly cerium (57.9%), lanthanum (34.0%) and praseodymium (6.5%). The feeding trial was divided into a growing period for 8 weeks and a fattening period for 39 weeks. The growing diet consisted of concentrate, grass silage and grass hay, while the fattening diet consisted of concentrate and maize silage. The animals were slaughtered at approximately 556 kg LW. The intake of grass hay and maize silage (0.55-0.31 kg/d and 6.09-5.44 kg/d, respectively) decreased linearly (p < 0.05) with increasing REE-citrate supplementation, while LW gain showed only a numerical decrease during the growing (2-4%) and the fattening period (4-5%). The feed-to-gain ratio and ME-to-gain ratio were not significantly affected by REE treatment during the whole feeding trial. The most striking effect of REE on carcass characteristics was a significantly higher dressing percentage in Group C (200 mg REE citrate kg/DM) compared to the other groups, while no effects were found on liver, kidneys, heart, thymus, pancreas, spleen and thyroid gland weights. The digestibility trials with wethers indicate that a supplementation of 300 mg REE-citrate per kg DM to a ration consisting of concentrate and straw does not enhance the digestibility of nutrients. These results suggest that, under the conditions of the present study, the supplementation of fattening bull diets with REE cannot be recommended.
本剂量反应研究的目的是检验饮食中增加稀土元素（REE）含量对育肥公牛生长和屠宰性能的长期影响。共有 48 头平均初始活重（LW）为 119 + 13 公斤的德国荷斯坦公牛被分为四组日粮处理组（n = 12）：对照组和三组 REE 处理组，分别用含有主要铈（57.9%）、镧（34.0%）和镨（6.5%）的 100、200 和 300 mg REE 柠檬酸盐/kg 干物质（DM）补充剂喂养。饲养试验分为 8 周的生长期和 39 周的育肥期。生长期的饲料由浓缩饲料、草青贮料和干草组成，而育肥期的饲料由浓缩饲料和玉米青贮料组成。动物在大约 556 公斤 LW 时被屠宰。干草和玉米青贮料的摄入量（分别为 0.55-0.31 公斤/天和 6.09-5.44 公斤/天）随 REE 柠檬酸盐补充量的增加呈线性下降（p < 0.05），而 LW 增益仅在生长期间（2-4%）和育肥期间（4-5%）出现数值下降。整个饲养试验中，REE 处理对饲料增重比和 ME 增重比没有显著影响。REE 对胴体特性最显著的影响是 C 组（200 mg REE 柠檬酸盐/kg DM）的屠宰率明显高于其他组，而对肝脏、肾脏、心脏、胸腺、胰腺、脾脏和甲状腺重量没有影响。用绵羊进行的消化试验表明，在浓缩饲料和秸秆日粮中补充 300 mg REE 柠檬酸盐/kg DM 并不能提高养分的消化率。这些结果表明，在本研究条件下，不能推荐在育肥公牛日粮中添加 REE。
