%0 Journal Article %T Effect of dietary betaine supplementation and vitamin B12 injection during the transition period on fatty acids profile of milk in Holstein dairy cows %J Iranian Journal of animal Science %I پردیس کشاورزی و منابع طبیعی دانشگاه تهران %Z 2008-4773 %A Gohardust, Ali %A Azarfar, Arash %A Kiani, Ali %A Fadayifar, Amir %D 2018 %\ 02/20/2018 %V 48 %N 4 %P 493-503 %! Effect of dietary betaine supplementation and vitamin B12 injection during the transition period on fatty acids profile of milk in Holstein dairy cows %K betaine %K milk fatty acid %K transition dairy cow %K vitamin B12 %R 10.22059/ijas.2017.243378.653567 %X In this research effects of dietary supplemention with betaine and injection of vitamin B12 during the transition period on profile of milk fatty acids was investigated using 32 Holstein dairy cows. Experimental treatments included control (a basal diet without any supplementation; CC), CB (supplemnting with 50 g of rumen unprotected betaine per day per head during the transition period), BC (injection of 0.5 mg vitamin B12 in a 10-days interval) and CC (supplemnting with 50 g of unprotected betaine per day per head plus injection of 0.5 mg vitamin B12 in a 10-days interval. The CB and BB significantly increased denovo synthesis of fatty acids in mammary gland and milk fat concentration of saturated fatty acids (P<0.05). Experimental treatments had no effect on milk fat concentratios of total mono-unsaturated fatty acids, C14: 1, C16: 1, C18: 1n9t, C18:1n9c and C20:1 (P> 0.05). Milk fat concentration of polyunsaturated fatty acids was higher in cows recived CB than in BC and BB cows, but similar to CC cows. Experimental treatments had no effect on perentage of milk fat and plasma concentration of glucose (P>0.05). In conclusion, to inceraese denovo synthesis of fatty acids in mammary glands intarmuscualr injection of vitamin B12 in transition cows is recommended.  %U https://ijas.ut.ac.ir/article_65465_2c05563be97a14b0f12617cf0523a5e5.pdf