Morris J G, Peterson R G
J Nutr. 1975 May;105(5):595-8. doi: 10.1093/jn/105.5.595.
At parturition, lactating ewes were given ad libitum one of six diets containing either a basal level of sodium (200 ppm Na) or basal plus 12.5, 25, 37.5, 50, or 100% of the National Research Council (NRC) allowance of sodium for lactating ewes (equivalent to 0.5% of the ration as sodium chloride). Deionized water was supplied to the ewes with a sodium concentration of less than 0.5 ppm. The parotid Na+:K+ ratio was taken as an index of sodium adequacy. At 4, 6, and 8 weeks postpartum, there was a positive rectilinear relationship between the Na+:K+ ratio of the parotid saliva and level of sodium in the diet up to 37.5% of the NRC allowance. The Na+:K+ ratio of parotid saliva from ewes consuming 37.5% or greater of the NCR allowance was not affected by the level of sodium in the diet. It was concluded that the NCR allowance for sodium for lactating ewes was excessive, and an allowance of 870 mg/kg diet was adequate for the maintenance of a normal Na+:K+ ratio of the parotid saliva.
分娩时，给正在泌乳的母羊随意提供六种日粮中的一种，这些日粮含有基础水平的钠（200 ppm钠）或基础水平加上相当于泌乳母羊钠的美国国家研究委员会（NRC）推荐量的12.5%、25%、37.5%、50%或100%（相当于日粮的0.5%氯化钠）。向母羊提供钠浓度低于0.5 ppm的去离子水。腮腺钠钾比作为钠充足的指标。产后4周、6周和8周时，腮腺唾液的钠钾比与日粮中钠水平之间存在正线性关系，直至达到NRC推荐量的37.5%。摄入NRC推荐量37.5%或更多的母羊腮腺唾液的钠钾比不受日粮中钠水平的影响。得出的结论是，泌乳母羊的NRC钠推荐量过高，日粮中870 mg/kg的推荐量足以维持腮腺唾液正常的钠钾比。
