J Y Guo，T J Pasquetti，S W Kim
本研究旨在评估饲喂降低阳离子-阴离子差值（DCAD）引起的酸化日粮对泌乳期母猪酸碱平衡、血液和乳汁及尿液钙浓度的影响。试验选用30头经产母猪（胎次：4.5±2.9）随机分为两组，CON组（对照组，玉米-豆粕型日粮，在妊娠后期和泌乳期DCAD值分别为170和226 mEq/kg）和ACI组（酸化日粮，比对照组DCAD值低100 mEq /kg）；低DCAD日粮是通过添加酸化矿物质获得的，DCAD值是作为mEq（Na + K – Cl）日粮计算的。在母猪妊娠94d到分娩阶段每天饲喂2kg饲粮，泌乳期自由采食。检测母猪血液和尿液中pH和钙、血清常量矿物质和生化指标、钙调节激素类以及乳汁组成成分。
试验数据显示，与CON组比较：在泌乳1天，ACI组母猪血液pH显著降低（P < 0.05）；在妊娠108天，泌乳1天、9天和18天，ACI组母猪尿液pH显著降低（P < 0.05）；在泌乳1和18天，ACI组母猪血清总钙浓度显著升高（P < 0.05）；ACI组母猪初乳中钙浓度显著升高（P < 0.05）。泌乳期两组间尿钙浓度无显著差异，在泌乳1和18天时，甲状旁腺素和1,25-二羟胆钙化醇浓度无显著差异；泌乳18天时，两组血清中碱性磷酸酶浓度相似（P = 0.086）。在泌乳1天时，ACI组母猪血清中Cl浓度显著升高（P < 0.05）。两组间母猪采食量、体重损失和产仔性能无差异。
Lowering dietary cation-anion difference increases sow blood and milk calcium concentrations
A study was conducted to evaluate the effects of feeding an acidogenic diet with a low dietary cation-anion difference (DCAD) on acid-base balance, blood, milk and urine Ca concentrations of sows during lactation. A total of 30 multiparous sows (parity: 4.5 ± 2.9, Smithfield Premium Genetic, Rose Hill, NC) were allotted to one of two dietary treatments: CON (control diets were corn-soybean meal based with a calculated DCAD of 170 and 226 mEq/kg during late gestation and lactation, respectively) or ACI (acidogenic diets had a DCAD 100 mEq/kg lower than the control diets). The lower DCAD was achieved by the addition of an acidogenic mineral. The DCAD was calculated as mEq (Na + K – Cl)/kg diet. Sows had a daily access to 2 kg feed from d 94 of gestation to parturition and ad libitum access to feed during lactation. Blood and urine pH and Ca, serum macrominerals, serum biochemistry, Ca-regulating hormones, and milk composition were measured. Sows in ACI had a lower (P < 0.05) blood pH than sows in CON at d 1 of lactation. Sows in ACI had a lower (P < 0.05) urine pH at d 108 of gestation, d 1, 9, and 18 of lactation compared with sows in CON. Sows in ACI had greater (P < 0.05) concentrations of serum total Ca at d 1 and 18 of lactation than sows in CON. There was a greater (P < 0.05) concentration of colostrum Ca in ACI than in CON. There was no difference in urine Ca concentration between treatments during lactation. Concentrations of parathyroid hormone and 1,25-dihydroxycholecalciferol were not different between treatments at either d 1 or 18 of lactation. Sows in ACI tended to have a smaller (P = 0.086) concentration of total alkaline phosphatase in serum at d 18 of lactation compared with sows in CON. At d 1 of lactation, the concentration of serum Cl in ACI was greater (P < 0.05) than that in CON. Feed intake, BW loss, and litter performance were not different between treatments. Collectively, feeding an acidogenic diet with a low DCAD to sows can induce a mild metabolic acidosis at farrowing, reduce the urine pH consistently, and increase serum total Ca and colostrum Ca concentrations during lactation but without altering the parathyroid hormone and 1,25-dihydroxycholecalciferol levels during lactation.