THE EFFECTS OF OXALATE IN TROPICAL GRASSES ON CALCIUM, PHOSPHORUS AND MAGNESIUM AVAILABILITY TO CATTLE
THE EFFECTS OF OXALATE IN TROPICAL GRASSES ON CALCIUM, PHOSPHORUS AND MAGNESIUM AVAILABILITY TO CATTLE
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DOI：
10.1017/s0021859600031208
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发表时间：
1982-01-01
影响因子：
2
通讯作者：
HEAD, TA
中科院分区：
文献类型：
--
作者：
BLANEY, BJ;GARTNER, RJW;HEAD, TA
分别饲喂4日龄牛进行矿物质平衡试验。两种干草（Cenchrus ciliaris和Setaria sphacelata vart . sericea）的草酸盐总量分别为1.8和1.3%，钙的摄取量分别高于和低于维持水平。这些草含有草酸钙晶体。另外2种干草（Aristida spp.- bothriochloa spp.混合物和Triticum aestivum）草酸含量为0.1%，也提供高于和低于维持摄取量的Ca。草酸含量高于维持摄取量的干草的Ca吸收量为高草酸干草的51%和低草酸干草的57%。低于维持日采食量时，牛处于负钙平衡状态，高草酸干草钙吸收量为52%，低草酸干草钙吸收量为64%。在负钙平衡状态下，给牛喂单剂量草酸钙，然后喂单剂量石灰石或磷酸盐岩。草酸钙对草酸钙钙的吸收达到了正平衡，但草酸钙对草酸钙钙的吸收量仅为石灰石钙的52%。饲喂草酸钙的牛也从草酸钙中吸收钙，但吸收量不足，不能达到钙正平衡。其吸收量是磷矿粉吸收量的47%。在含有草酸钙晶体的热带禾草中，Ca的可用性约为。比草酸含量低20%。对草酸盐的适应可以提高瘤胃对草酸钙的利用能力。对放牧热带牧草的牛来说，钙的可利用性最高可达50%。草酸不影响热带牧草对镁和磷的吸收。
Cattle were fed 4 hays in mineral balance experiments. Two of the hays (Cenchrus ciliaris and Setaria sphacelata var. sericea) contained 1.8 and 1.3% total oxalates and provided above- and below-maintenance intakes of Ca, respectively. These grasses contain calcium oxalate crystals. The other 2 hays (Aristida spp.-Bothriochloa spp. mixture and Triticum aestivum) contained 0.1% oxalates, and also provided above- and below-maintenance intakes of Ca. The absorptions of Ca from the hays providing above-maintenance intakes were 51% for the high and 57% for the low oxalate hay. At below-maintenance intakes, the cattle were in negative Ca balance and Ca absorptions were 52% for the high and 64% for the low oxalate hay. While in negative Ca balance the cattle were given single doses of calcium oxalate, followed by single doses of either limestone or rock phosphate. The cattle fed S. sphacelata hay absorbed sufficient Ca from calcium oxalate to achieve positive Ca balance, although the amount absorbed was only 52% of that absorbed from limestone. The cattle fed T. aestivum hay also absorbed Ca from calcium oxalate, but in insufficient amount to result in a positive Ca balance. The amount absorbed was 47% of that absorbed from rock phosphate. In tropical grasses containing calcium oxalate crystals, the availability of Ca is .apprx. 20% lower than it is in grasses containing little oxalate. Adaptation to oxalate may improve the ability of the rumen to utilize calcium oxalate. The availability of Ca to cattle grazing tropical grasses should be considered to be a maximum of 50%. Neither Mg nor P absorptions from tropical grasses were affected by oxalate.