| To study ideal balance model of milk components precursors(MCP) in external pudendal artery(EPA) of Guanzhong dairy goats, the experiment was conducted to study the effects of MCP concentration in EPA on uptake and extraction of milk protein precursors(MPP), milk fat precursors(MFP), milk lactose precursors(MLP) in mammary gland and changes of related hormone in subcutaneous abdominal vein(SAV) as well as the expression of related hormone receptor mRNA in mammary tissue of dairy goats infusing MCP into EPA used blood vessel intubation technique.(1) Influence on milk production and milk content and the MCP concentration in EPA of dairy goats by different NFC/NDF dietsSix dairy goats aged from 2 to 3 years which had similar body weight and milk production were selected to do blood vessel intubation in EPA and SAV, divided two sets and feeded different NFC/NDF diets(â… andâ…¡), collecting arteriovenous plasma, in order to measure mammary gland blood flow(MBF) and MCP concentration in EPA of dairy goats. The result showed that MBF didn't changed(P>0.05) and the average of MBF was 124.8L/d, the average of mammary gland plasma flow(MPF) was 83.2 L/d; MLP concentration was significantly difference(P<0.05) and MPP concentration, MFP concentration was no significantly difference(P>0.05) by different NFC/NDF diets. The influence on milk production and milk content of dairy goat was no significantly difference(P>0.05).(2) Influence on milk production and milk content as well as the uptake and extraction of MCP in mammary gland of dairy goats infusing different balance models of amino acids into EPASix dairy goats aged from 2 to 3 years which had similar body weight and milk production were selected to do blood vessel intubation in EPA and SAV, divided two sets and feeded different NFC/NDF diets, infusing different balance models of amino acids into EPA, collecting arteriovenous plasma around the infusion, in order to measure the changes of MCP as well as the uptake and extraction in mammary gland. The result showed that the uptake of MCP in mammary gland were step up infusing different balance models of amino acids into EPA; compared with control group, the milk production and milk content of dairy goats were significantly difference(P<0.05) by diets I, the milk production and milk content of dairy goats were no significantly difference(P>0.05) expect the milk fat was significantly difference(P<0.05) in balance model group by dietsâ…¡; the uptake of MCP in mammary gland was best infusing essential amino acid(EAA) 6.03g/d (AABI=0.972) when NFC/NDF was 1.03 in dies, at this time the balance model of MCP(MPP:MFP:MLP) was 15:20:65.(3) Influence on milk production and milk content as well as the uptake and extraction of MCP in mammary gland of dairy goats infusing different ideal balance models of amino acids and glucose into EPASix dairy goats aged from 2 to 3 years which had similar body weight and milk production were selected to do blood vessel intubation in EPA and SAV, divided two sets and feeded diets I, infusing a mixture of amino acids and glucose into EPA at treatment groups and infusing glucose into EPA at control groups, collecting arteriovenous plasma around the infusion, in order to measure the changes of MCP as well as the uptake and extraction in mammary gland. The result showed that the uptake of MCP in mammary gland were step up infusing a mixture of amino acids and glucose into EPA; the uptake of MCP in mammary gland was best infusing a mixture of EAA 6.03g/d (AABI=0.972) and glucose 45g/d when NFC/NDF was 1.03 in dies, and the milk production and milk content of dairy goats were significantly difference(P<0.05) compared with control group; The ideal balance model of MCP (MPP:MFP:MLP) was 15.2:18.7:66.1 in EPA of Guanzhong dairy goats.(4) Influence of IGF-â… ,PRL,GH,ACC,FAS in SAV and the expression of IGF-â… ,PRLR,GHR mRNA in mammary tissue of dairy goats infusing ideal balance model of amino acids and glucose into EPAThree dairy goats aged from 2 to 3 years which had similar body weight and milk production were selected to do blood vessel intubation in EPA and SAV, feeded diets I, infusing a mixture of EAA 6.03g/d (AABI=0.972) and glucose 45g/d into EPA and collecting SAV plasma and mammary tissue around the infusion, in order to measure the changes of growth hormone(GH), prolactin(PRL), insulin-like growth factor-I(IGF-I), acetyl CoA carboxylase (ACC), fatty acid synthetase(FAS) and the mRNA expression of IGF-â… ,growth hormone receptor(GHR) and prolactin receptor(PRLR) in mammary tissue. Compared with the control group, the concentration of IGF-I, GH and PRL were significantly increased(P<0.05), the concentration of ACC and FAS were no significantly difference(P>0.05);The mRNA expression of GHR and IGF-I in mammary tissue were significantly increased (P<0.05), while that of PRLR was also significantly increased (P<0.01).In summary, the above results indicated that the changes of MCP concentration can affect the uptake of MCP and significantly promote concentration of related hormone in SAV and the mRNA expression of related hormone receptor in mammary tissue, which is in favor of the synthesis of milk.
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