الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
 |  | from | 99 |  |  |
| | | from | 99 | | |
Abstract
Soybeans and their derivatives in cow rations are an important source of essential amino acids. Various methods of treating SBM have been studied to alter the rate and extent of protein degradation in the rumen over the last 25 years. Some of the techniques, e.g., extrusion, roasting, expeller, lignosulfonate, and formaldehyde have been successfully used to protect SBM from ruminal degradation. In addition, if SBM properly heat treated, soybean meal can provide additional rumen undegradable protein (RUP). SoyBest® is one of the best heat-treated soybean meals, as it contains a high amount of RUP, that has a high ability to pass from the rumen to the small intestine. Heat treatment of soybeans increases its efficiency by blocking anti-nutritional agents such as trypsin inhibitors. Therefore, this study was a purpose to evaluate the performance of early-lactating cows fed diets in which soybean meal (SBM) protein was partially replaced by 10.52 % of expeller SBM (ESM, SoyBest®) protein to evaluate the impact of ESM as a source of RUP supplement in terms of milk production and its various components, digestibility coefficients of nutritional components, blood biochemical measurements and the economic evaluation. One hundred early-lactation Holstein cows with an average body weight of 650.1±52.10 kg and lactation season 2.5 were randomly allocated into to equal 2 groups for 3 months experimental period. The first group served as control (CTL), cows were fed total mixed ration (TMR) including soybean meal (SBM), and the second group (treatment) were fed TMR with partial replacement of SBM protein by 10.52 % of Soybest®. Diets and water were offered ad
libitum during the experiment, and cows were milked three times daily. Dry matter intake (DMI) and milk production were observed throughout the trial. The milk composition and fatty acid 86 profile were measured as well. Blood and faeces samples were collected for evaluating blood metabolites and nutrient digestibility, respectively. Also, the net return over feed cost and economic efficiency were calculated for both control and treatment diets. Results depicted that DMI, and milk yield were increased (P<0.05) in the treatment group as opposed to the control group. In contrast, FCM yield, ECM yield and percentage or yield of milk fat, lactose, protein, or solids not-fat were reduced (P<0.05) in the treatment group opposite to the control group. As for the nutrients’ digestibility, the apparent OM digestibility was substantially higher (P<0.05) in the treated group than the control group. Conversely, NDF and hemicellulose were decreased (P<0.05) in the digestibility coefficients of the treated group as opposed to the control group, but no differences were observed between groups in CP, ADF and cellulose digestibility coefficients. On the other hand, no significant differences were observed in blood metabolites between groups. Moreover, the partial inclusion of Soybest® in the lactating cow diet has no significant impact on net profit. In conclusion, the results of the current study and under the conditions of this experiment on early lactating dairy cows stated that the partial replacement of Soybest® instead of SBM had no significant impacts on dairy cows’ productivity and net profit.