Effect Of Different Types Of Diets On Milk Fatty Acid Composition Of Dairy Cow

This study was carried out to investage the effect of two different types of dietson productive performance, milk composition, milk fatty acid profile and differentfatty acids metabolize in alimentary tract.Experiment Ⅰ: Our experiment was conducted to investage two different typesof diets on productive performance, milk composition, milk fatty acid profile, anddesaturase indices of mammary gland of dairy cow. Twenty-four China lactatingHolstein dairy cows were randomly assigned to two treatments, with similar bodyweight, milk yield and days in milk. The two treatments were corn straw treatment(CS) and mixed forage treatment (MF). The trial lasted9weeks. The first2weekswas preliminary period, followed by a7-week sample collecting period. Comparedwith CS treatment, cows fed MF diet had positive effects (P<0.05) on dry matterintake, milk fat yield, and total solid yield, there was no difference on otherproductive performance and milk composition target. Meanwhile, compared with CStreatment, MF diets significantly increased C18:0, C18:3and C20:0content in milkfat (P<0.05); Compared with MF treatment, CS diets tented to increase C8:0, C10:0,C12:0and C14:1content in milk fat (P<0.05), CS diet also had positive effect on fattyacid with C<16. Furthermore, CS diet had positive effect on C14:1/C14:0(P=0.06)、C16:1/C16:0(P=0.08) and cis9C18:1/C18:0(P=0.01), indicated that CS diet hadpositive effects on stearoyl-coenzyme A desaturase activity.Experiment Ⅱ: This part was desgined to investage different fatty acids intakeand metablize in alimentary tract response to cows fed different types of diets. Weselected twelve Chinese lactating Holstein dairy cows for this study. Cows wererandomly assigned to two treatments, with similar body weight, milk yield and day inmilk. The other concrete way was similar with the part1. Compared to CS treatment,cows fed MF diet significantly increased C14:0, C16:0, C18:0, cis9C18:1, cis9,cis12C18:2and C18:3intake (P<0.05); significantly increased C8:0, C14:0, C16:0,C16:1, C18:0, trans9C18:1, trans11C18:1, C18:3,18CFA and18CUFA flow induodenum (P<0.05); significantly increased C14:0and C16:0digestibility inalimentary tract (P<0.05). Furthermore, compared MF treatment, cows fed CS dietsignificantly C12:0digestibiliy in alimentary tract (P<0.05), and transC18:1tended toincrease in rumen liquild (P=0.12).