Weisstaub Adriana R, Zeni Susana, de Portela María L, Ronayne de Ferrer Patricia A
Cátedras de Bromatología y Nutrición, Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, Junín 956, 2 p, (1113) Buenos Aires, Argentina.
J Trace Elem Med Biol. 2006;20(1):41-7. doi: 10.1016/j.jtemb.2006.01.001. Epub 2006 Mar 6.
The aim of this study was to analyze zinc (Zn), calcium (Ca) and phosphorus (P) contents in milk and the lactational performance in rats fed different Ca levels. Female Wistar rats were fed during pregnancy and lactation with experimental diets containing 20% protein and high (0.90%, HCa), normal (0.60%, NCa) or low (0.20%, LCa) Ca levels. Milk samples were collected after 15 days to determine the milk mineral composition. Pup weight was recorded from birth to weaning (litter size: 6-8 pups) to determine weight gain and calculate milk production. At delivery there were no significant differences in the body weight of the pups between the groups, but at day 15, the LCa group showed lower values than both NCa and HCa groups (p<0.05). The weight gain of the LCa group was significantly lower than of the HCa and NCa groups, between delivery and day 5 (p<0.05). This reduced rate of weight gain led to the LCa group reaching weaning weight later than the other groups. Milk production (g/pup/day) was significantly lower when dams were fed the LCa than the NCa and HCa diets (p<0.05). There were no significant differences among the groups in milk Ca, P and Zn levels and Ca/P ratio. The body mineral composition of the pups at birth did not differ between the groups; at weaning, however, both LCa and HCa groups had lower element contents than the NCa group (p<0.05). In conclusion, dams fed with a diet containing low Ca levels produced smaller volumes of milk and their pups reached weaning weights later than the other groups. As the milk mineral composition was not affected, it can be hypothesized that in dams fed low dietary Ca, the smaller milk yield might have been a way of maintaining milk quality. High Ca levels affected neither pregnancy outcome nor lactational performance.
本研究旨在分析牛奶中的锌（Zn）、钙（Ca）和磷（P）含量，以及喂食不同钙水平饲料的大鼠的泌乳性能。雌性Wistar大鼠在怀孕和哺乳期喂食含20%蛋白质且钙水平高（0.90%，HCa）、正常（0.60%，NCa）或低（0.20%，LCa）的实验饲料。15天后采集牛奶样本以测定牛奶矿物质成分。记录幼崽从出生到断奶（窝仔数：6 - 8只幼崽）的体重，以确定体重增加情况并计算产奶量。分娩时，各组幼崽的体重无显著差异，但在第15天，LCa组的值低于NCa组和HCa组（p<0.05）。在分娩至第5天期间，LCa组的体重增加显著低于HCa组和NCa组（p<0.05）。这种体重增加率的降低导致LCa组比其他组更晚达到断奶体重。当母鼠喂食LCa饲料时，产奶量（克/幼崽/天）显著低于喂食NCa和HCa饲料时（p<0.05）。各组牛奶中的钙、磷和锌水平以及钙/磷比值无显著差异。出生时幼崽的身体矿物质成分在各组之间没有差异；然而，在断奶时，LCa组和HCa组的元素含量均低于NCa组（p<0.05）。总之，喂食低钙水平饲料的母鼠产奶量较少，其幼崽比其他组更晚达到断奶体重。由于牛奶矿物质成分未受影响，可以推测，喂食低钙饮食的母鼠，产奶量减少可能是维持牛奶质量的一种方式。高钙水平对妊娠结局和泌乳性能均无影响。
