Marín-García Pablo Jesús, López-Luján Mari Carmen, Ródenas Luís, Martínez-Paredes Eugenio Melchor, Blas Enrique, Pascual Juan José
Institute for Animal Science and Technology, Universitat Politècnica de València, Camino de Vera s/n, 46022 Valencia, Spain.
Animals (Basel). 2020 May 29;10(6):946. doi: 10.3390/ani10060946.
A total of 27 experimental diets were formulated starting from the same basal mixture, with a moderate content of crude protein and digestible energy (155 g and 9.86 MJ/kg of digestible matter (DM), respectively, both estimated). The contents of lysine, sulphur amino acids and threonine were variable. The first one, close to the current recommendations (Medium, M; 8.1, 5.8 and 6.9 g/kg DM for lysine, sulphur amino acids and threonine, respectively), and two other levels were on average 15% higher (High, H; 9.4, 6.6 and 7.8 g/kg DM for lysine, sulphur amino acids and threonine, respectively) or lower (Low, L; 6.7, 4.9 and 5.7 g/kg DM for lysine, sulphur amino acids and threonine, respectively). Diets were named with three letters, indicating lysine, sulphur amino acids and threonine levels, respectively. In total, 918 weaned rabbits (28 days old) were used (34 per diet). At weaning, animals were fed ad libitum with a commercial diet until day 46, day 47 each collective cage was randomly switched to one experimental diet. At day 48, blood samples were collected at 08:00h then the animals were subjected to 10 h of fasting and a second blood sample was extracted at 21.00h. At 08:00h, Pasmatic urea nitrogen (PUN) was higher with the L level of lysine ( < 0.001), unaffected by the level of sulphur amino acids and increased with the level of threonine ( < 0.001). At 21:00h, minimum PUN was observed with the MHL diet (14.72 ± 0.661 mg/dL). Taken into account the usual recommendations (established for a diet containing 11.3 MJ DE/kg DM, and then being 0.72, 0.51 and 0.61 g/MJ DE for lysine, sulphur amino acids and threonine, respectively), these results suggest that a diet containing more lysine and sulphur amino acids per energy unit (around 0.82 and 0.67 g/MJ DE) could better fit the growing rabbit requirements, although studies on the effects of such a diet on performance and protein retention are necessary.
从相同的基础混合物开始配制了总共27种实验日粮，粗蛋白和可消化能量含量适中（分别估计为155克和9.86兆焦/千克可消化物质（DM））。赖氨酸、含硫氨基酸和苏氨酸的含量各不相同。第一种日粮接近当前建议水平（中等，M；赖氨酸、含硫氨基酸和苏氨酸分别为8.1、5.8和6.9克/千克DM），另外两个水平平均高15%（高，H；赖氨酸、含硫氨基酸和苏氨酸分别为9.4、6.6和7.8克/千克DM）或低15%（低，L；赖氨酸、含硫氨基酸和苏氨酸分别为6.7、4.9和5.7克/千克DM）。日粮用三个字母命名，分别表示赖氨酸、含硫氨基酸和苏氨酸水平。总共使用了918只断奶兔子（28日龄）（每种日粮34只）。断奶时，动物自由采食商业日粮至46日龄，47日龄时每个集体笼随机转换为一种实验日粮。48日龄时，08:00采集血样，然后动物禁食10小时，21:0时采集第二份血样。08:00时，赖氨酸L水平组的血浆尿素氮（PUN）较高（<0.001），不受含硫氨基酸水平影响，随苏氨酸水平升高而升高（<0.001）。21:00时，MHL日粮组的PUN最低（14.72±0.661毫克/分升）。考虑到通常的建议（针对含11.3兆焦消化能/千克DM的日粮制定，赖氨酸、含硫氨基酸和苏氨酸分别为0.72、0.51和0.61克/兆焦消化能），这些结果表明，每能量单位含有更多赖氨酸和含硫氨基酸（约0.82和0.67克/兆焦消化能）的日粮可能更符合生长兔的需求，尽管有必要研究这种日粮对生产性能和蛋白质保留的影响。
