Leonard R P, Speer V C
J Anim Sci. 1983 Jun;56(6):1345-53. doi: 10.2527/jas1983.5661345x.
An experiment was conducted to estimate the threonine requirement of pregnant swine. L-threonine was added to a fortified corn-gelatin diet and fed at a rate to provide five threonine levels of 3.59, 4.95, 6.31, 7.67 and 9.03 g/d. Twenty-five crossbred gilts were randomly assigned to these five dietary treatments. Increasing threonine resulted in a difference (P less than .01) in nitrogen (N) retention, with maximum retention at 4.95 g/d threonine intake. Blood samples were drawn before and after feeding. Although plasma urea N did not change significantly, the lowest level occurred at an intake of 4.95 g/d threonine. As threonine intake increased, plasma threonine increased quadratically (P less than .05). This increase was accompanied by a quadratic (P less than .005) decrease in plasma lysine. Sow weight gains increased quadratically (P less than .01) with increasing threonine levels. Litter weight, number of pigs born, baby pig gains, daily milk yield and milk protein were not influenced by threonine levels. The lysine-alpha-ketoglutarate reductase activity of the sow liver samples increased linearly (P less than .05) as dietary threonine levels increased. Based upon metabolic criteria 4.95 g/d L-threonine met the requirement for animals in this experiment. If 75% of threonine in a corn-soybean meal diet is available, the threonine requirement for reproduction would be no higher than 5.4 g/d or .30% dietary threonine when daily feed intake is 1.82 kg.
进行了一项实验来估计妊娠母猪的苏氨酸需求量。在强化玉米 - 明胶日粮中添加L - 苏氨酸，并以一定速率饲喂，以提供3.59、4.95、6.31、7.67和9.03 g/d这五个苏氨酸水平。25头杂种后备母猪被随机分配到这五种日粮处理组。苏氨酸增加导致氮保留量出现差异（P小于0.01），在苏氨酸摄入量为4.95 g/d时氮保留量最高。在饲喂前后采集血样。虽然血浆尿素氮没有显著变化，但最低水平出现在苏氨酸摄入量为4.95 g/d时。随着苏氨酸摄入量增加，血浆苏氨酸呈二次方增加（P小于0.05）。这种增加伴随着血浆赖氨酸的二次方减少（P小于0.005）。随着苏氨酸水平升高，母猪体重增加呈二次方增加（P小于0.01）。窝重、产仔数、仔猪增重、每日泌乳量和乳蛋白不受苏氨酸水平影响。随着日粮苏氨酸水平升高，母猪肝脏样品的赖氨酸-α-酮戊二酸还原酶活性呈线性增加（P小于0.05）。基于代谢标准，4.95 g/d的L - 苏氨酸满足本实验中动物的需求。如果玉米 - 豆粕日粮中75%的苏氨酸可利用，当每日采食量为1.82 kg时，繁殖所需的苏氨酸不高于5.4 g/d或日粮苏氨酸的0.30%。
