| The test choose dairy cows from different areas of Inner Mongolia,360 Hostein cows from Hohhot and BayanNour;90 Hostein cows and 90 Simmental cows from Tongliao;90 Hostein cows and 90 Sanhe cows from HulunBuir.In order to compare and study the content and difference of protein,fat, lactose,dry matter, casein and amino acid in milk which from different areas,feeding mode,season,breed,fetal time,lactation period,to analyze the effect on contents of amino acid in milk and variational regulation on amino acid content and milk in different conditions.The results showed that:In different regions: The content of protein and fat in the milk for the Holstein in Tongliao and Hulun Buir were significantly higher than that of the Holstein in Hohhot and Bayan Nur (P<0.05); In Hohhot, BayanNur, Tongliao and HulunBuir milk protein content were respectively 3.19%,3.11%,3.37% and3.31%; there were no significant difference from the content of the total dry matter, lactose and the casein in the milk (P>0.05);the content of amino acid in the milk of the Holstein in Tongliao and Hulun Buir were significantly higher than that of the Holstein in Hohhot and Bayan Nur (P<0.05).In different breed: The content of protein,fat and total dry matter in the milk for the Simmentals and Sanhe cows were significantly higher than that of the Holstein (P <0.05); Tongliao Holstein and Simmental milk protein content were respectively 3.61% and 3.37 %; HulunBuir Holstein and Sanhe milk protein content were 3.31% and 3.52%. There were no significant difference from the content of lactose and the casein in the milk among the three breeds(P>0.05).It was specific of the amino acid in the milk FOR the Simmentals and Sanhe cows that the content of the amino acid was significantly higher than that of the Holstein(P<0.05).In different fetal time: The content of protein in the milk of the first and third fetal time Simmentals and Sanhe were significantly higher than that of the fifth fetal time (P<0.05), Simmental milk protein content were respectively 3.37%,3.0%和2.68%; Sanhe milk protein content were respectively 3.39%,3.18%和2.88%;but the content of milk protein in the different fetal time Holstein,there were no significant difference in the content of the rest nutritional ingredients in the different milk periods(P>0.05). The content of amino acid in milk between Simmentals and Sanhe were significantly(P<0.05).In different Lactation period: The content of milk protein in the Holstein,Simmentals,Sanhe in early lactation and later lactation were significantly higher than that of the middle lactation (P<0.05); In early lactation, middle and post Holstein milk protein content were respectively 3.37%,3.05% and 3.4%; Simmental milk protein content were respectively 3.21%, 3.07% and 3.38%; milk protein content in Sanhe cows were respectively 3.36%, 3.06% and 3.5%. There were no significant difference in the milk content of the rest nutritional ingredients among the three lactations (P >0.05), difference the content of amino acid among the three lactations were significant(P<0.05).In different seasons: Protein and fat content in the Green,Green-grass muturity and pre-subtili period milky was significantly lower than that in the late subtilis (P<0.05), The milky protein were 3.09%, 3.05%, 3.02% and 3.5% respectively at all season in Huhhot Hosten dairy cows; The milky protein were 3.12%,3.06%, 3.03% and 3.21% respectively at all season in Bayan Nur Hosten dairy cows; The milky protein were 3.14%, 3.11%, 3.1% and 3.49% respectively at all season in Tongliao Hosten dairy cows; The milky protein were 3.06%, 3.11%, 3.20% and 3.49% respectively at all season in Hulun Buir Hosten dairy cows.Other milky nutrients contents were not significant at all seasons (P>0.05). Milky amino acids content wad lower compared in green period with in green-grass,pre-subtilis and post-subtilis periods.
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