Effect Of Compound Buffers And Dietary Composition On Milk Performance And Milk Composition Of Dairy Cows

Six Holstein cows were used to study the effect of premix and compound buffers on milk production and milk composition. The design was a 3 x 3 Latin square,in which the three treatments were: (I) basal diet + a kind of commercial premix(1%)(CPRX); (II) basal diet + a new type of premix(1%)(NPRX); (III)basal diet + the new type of premix(1%)+ compound buffers(PRXBUFF). PRXBUFF can significantly increase the rumen fluid pH and rumen buffering capacity,which is very beneficial to prevent ruminal acidosis of dairy cows fed high concentrate diets. It is also considered to be useful to prevent the overdigestion of proteins in rumen and increase amount of the by-pass nitrogen, which will improve the efficiency of utilizition of the proteins in diets. It also can increase the digestibility of forage and organnic matters,and improve the synthesis of microbial proteins.As the data has shown, the apparent digestibility of neutral detergent fiber and acid detergent fiber increase gradually from I to III ,but the difference is not significant(p<0.05). Milk production (22.67,23.13,23.98kg/d) for diets I to III were lowest for CPRX. Milk fat percentages (3.08%, 3.16%, and 3.41%) for diets I to III were the lowest for CPRX. Compared with CPRX and NPRX, milk production and fat percentages of PRXBUFF increased significantly(p<0.01). Milk protein percentages do not differ among treatments(p>0.05),averaging 2.85%,2.83%,2.90% from I to III. Blood glucose concentions (74.33,73.00,86.83 mg/dl) for diets I to III were the highest for PRXBUFF ; BUN concentions (10.10,8.87,9.12 mg/dl) for diets I to III were the lowest for PRXBUFF.The objective of the experiment two is to examine the effect of feeding seeds riched in linoleic or linolenic acids in order to determine which would alter the content of conjugated linoleic acid (CLA) , and unsaturated fatty acids in milk fat and study their metabolic mechanism. Ten Holstein cows were used in a 4 x 5 incomplete Latin square with 4-wk periods. Treatment diets were 1) basal diet (BASAL), 2) basal diet was replaced partially by clover and formaldehyde-treated whole flaxseeds (high linolenic; FFLA), 3) basal diet was replaced partially by clover and whole flaxseeds (high linolenic; FLA), 4) basal diet was replaced partially by clover and formaldehyde -treated cracked soy (high linoleic; FSOY) , 5) basal diet was replaced partially by clover and cracked soy (high linoleic; SOY). Diets were designed to contain similar crude protein,crude fat and fibre.