Study On Effects Of The Deficiency Of Individual Essential Amino Acid On Mammary Amino Acid Metabolism In Lactating Goats

According to the principle of priority security of lactation of ruminants, when some kind of essential amino acid is at the first limiting position of lactation, the highest transformation efficiency of lactation will be achieved. This project aims to investigate the effect of deletion of amino acid on lactation performance and mammary amino acid metabolism and thus obtain ideal amino acid pattern in lactation metabolism of ruminants by infusing into abomasus amino acid mixed solutions without some kind of essential amino acid and making each essential amino acid at the first limiting position of lactation in turn. 4 pluriparous Saanen goats in good condition(milk yield: 1.5±0.25kg; weight: 50±5kg) were selected and abomasal fistula cannulas were installed. 4×4 Latin square design was used. Goats for trial were fed with basic ration to meet energy and protein needs for maintenance. Abomasus were infused non-stop with glucose and amino acid mixed solution for 24 hours to meet the need of lactation metabolism energy and protein. Infused amino acid mixed solutions respectively were TAA(containing EAA and NEAA), the one without Arg, the one without Thr or His,the one without Lys and the one without Met or Leu. The effect of deletion of amino acid on lactation metabolism and mammary amino acid metabolism was observed. Results showed:(1)After Abomasus were infused with amino acid mixed solutions respectively without Arg, Thr,Lys, Met(or Leu), the blood flow respectively increased by 22.2%, 20.6%,,8.7%, 11.2% and16.2%.(2) After Abomasus were infused with amino acid mixed solutions respectively without Arg, Thr, Lys, Met(or Leu), obvious reduce was observed in corresponding amino acid concentration in both the artery and vein, and the mammary extraction rate respectively increased by 25.9% 、 199% 、 104.9% 、 151% and 44%. Deletion of amino acid had no significant effect on concentration difference in both the artery and vein and mammary uptake except deletion of Arg and Leu, which obviously reduced corresponding amino acid concentration difference in both the artery and vein and mammary uptake. Deletion of amino acid had no significant effect on the U:O value of corresponding amino acid.(3) Infusion into Abomasus of amino acid mixed solutions respectively without Thr(or His), Lys and Met(or Leu) had no significant effect on lactation performance of breasts, but deletion of Arg obviously increased cream content and yield.(4) Infusion of amino acid mixed solutions respectively without Arg, Thr, Lys, Met(or Leu) into Abomasus substantially improved mammary lactation efficiency of corresponding amino acid or brought the tendency of improvement. The investigation proves: lactoprotein synthesis and secretion are not sensitive to the imbalance of amino acid concentration in artery caused by deletion of amino acid;lactoprotein secretion of breasts has the ability of self-adjustment in amino acid absorption and translocation and lactoprotein synthesis.