Trine F. Pedersen，Thomas S. Bruun，Nathalie L. Trottier，Peter K. Theil
翻译&校对：上海亘泰实业集团

这项研究的目的是：1）量化日粮中氮（N）用于乳汁中N利用和尿液、粪便中的N损失，母猪饲喂的日粮中粗蛋白（CP）水平增加，但是为了满足其标准化回肠消化率（SID）的需求，赖氨酸、蛋氨酸和苏氨酸、色氨酸的含量保持不变。2）根据日粮N被分泌的乳汁利用情况，确定最佳的日粮CP浓度。

试验选用72头泌乳母猪，随机分到1～6组处理组中的一组，按照SID CP水平配制饲料配方，SID CP水平分别为：11.8、12.8、13.4、14.0、14.7、15.6%，各处理组日粮能量一致（9.8 MJ NE/kg）。试验日粮从母猪分娩后第二天开始饲喂，到28d（±3d）断奶结束，每窝仔猪等量为14头，出生48h内称重。分别在泌乳18d（±3d）和28d（±3d）对母猪进行称重和检测背膘值；分别在哺乳11、18（±3d）和28（±3d）称量记录窝仔猪重量；在泌乳4、11、和18（±3d）进行N平衡统计分析；日产奶量由窝增重和窝仔数评估；为了计算母猪机体脂肪和蛋白的调动，在泌乳4和18d（±3d）用氘水（D2O）浓缩方法评估机体内脂肪和蛋白蓄积。

试验结果表明，在泌乳的第一周、第二周和第三周，随着日粮中CP水平的增加，乳汁中蛋白含量呈线性关系升高（P < 0.05、P < 0.05和P < 0.001）；同样的，随着日粮中CP水平的增加，第一周、第二周和第三周的尿N值呈直线升高（P = 0.05、P < 0.001和P < 0.001）；各日粮组间尿液排放没有差异。相对于N摄入量，随着日粮CP增加，尿N排放呈直线增加（P < 0.001）；从日粮处理组1到6，乳汁中N利用率从77.8%直线下降到63.1%（P< 0.001）；校正后乳汁中N利用率从68.6%下降到64.2%（P< 0.05）

综上所述，哺乳母猪日粮中含低CP水平，添加晶体氨基酸能够在不影响母猪泌乳性能的情况下提高日粮N利用率，减少尿氮排放。


Nitrogen utilization of lactating sows fed increasing dietary protein

The objectives of the study were 1) to quantify dietary N utilized for milk N and N loss in urine and feces, in sows fed increasing dietary CP with a constant amount of Lys, Met, Thr, and Trp to meet their standardized ileal digestible (SID) requirement and 2) to determine the optimal dietary CP concentration based on dietary N utilization for milk production. Seventy-two sows were fed 1 of 6 dietary treatments, formulated to increase the SID CP as followed: 11.8, 12.8, 13.4, 14.0, 14.7, and 15.6% and formulated to be isocaloric (9.8 MJ NE/kg). Diets were fed from day 2 after parturition until weaning at day 28 (± 3 d). Litters were equalized to 14 piglets and weighed within 48 h following parturition. Sows were weighed and back fat scanned, at day 18 (± 3 d) and day 28 (weaning; ± 3 d). Litter weight was recorded at day 11, 18 (± 3 d), and 28 (± 3 d). Nitrogen balances were conducted on approximately day 4, 11, and 18 (± 3 d). Daily milk yield was estimated from recorded litter gain and litter size. To calculate sows mobilization of fat and protein, body pools of fat and protein were estimated by D2O (deuterated water) enrichment on day 4 and 18 (± 3 d). No linear, quadratic, or cubic effects of increasing dietary CP was observed for sows total feed intake, sow BW, body pools of protein and fat, protein and fat mobilization, total milk yield, and piglet performance. The protein content in milk increased linearly with increasing dietary CP in week 1 (P < 0.05), week 2 (P < 0.05), and week 3 (P < 0.001). Urine production did not differ among treatments and N output in urine increased linearly with increasing dietary CP concentration in week 1 (P= 0.05), week 2 (P < 0.001), and week 3 (P < 0.001). Urine N excretion relative to N intake increased linearly with increasing dietary CP (P <0.001). Milk N utilization relative to N intake decreased linearly from 77.8% to 63.1% from treatment 1 through 6 (P < 0.001). Corrected milk N utilization decreased from 68.6% to 64.2% from treatment 1 through 6 (P < 0.05). In conclusion, a low dietary CP concentration for lactating sows with supplemented crystalline AA improved the efficiency of dietary N utilization and reduced the N output in urine without affecting lactation performance.（转自：猪营养国际论坛）