Effects of different levels of whole soybeans on performance of lactating Holstein dairy cows in early lactation period

Fifteen multiparous cows with mean weight 630+50 and 50+ 40 DIM were selected for comparison of different levels of soybean and allocated randomly to three treatments. The rations were fed to cows as total mixed ration and ad libitum. The cows were and milked three times a day and daily milk yield was recorded while milk samples taken once per week for determination of milk composition and samples of rumen liquor and blood were taken at the last week of experiment. Dry matter intake increased with increasing of soybean levels. The average of milk yield with respect to the rations 1-3 were 29. 9، 28. 9 and 28. 7 and fat corrected milkyield for 4% fat were 27. 4، 29. 2 and 28. 7 kg per day respectively. That it wasn’t significantly different. Milk composition including fat، protein، solid non fat and total solid percent were not affected. Treatments had no significant effect on feces PH and rumen pH. The average of weight change to body weight was 0. 2، 1. 8 and 4. 2 that was not significantly different. Chewing activity (minute per day) was numerically decreased in second diet، but chewing activity to dry matter intake was significantly decreased in second diet. Concentration of calcium، cholesterol، albumin، total protein، urea nitrogen، T3 and T4 in blood of cows receiving different diets were not different، while concentration of glucose and phosphorus in blood were different.