Rumagentin ™

Iowa State Abstract

Determining the Effectiveness of Proteases on Production Variables in Lactating Holstein Cows

E. Sucu ¹ ,², A. Nayeri ¹, M.V. Sanz-Fernandez¹, N.C. Upah ¹, S.C. Pearce1 and L.H. Baumgard ¹

¹ Department of Animal Science, Iowa State University, Ames

² Uludag University, Turkey, Bursa

Ninety-six multiparous lactating Holstein dairy cows (2.7±1.6 parity, 153.8±103.7 DIM, 40.3±5.9 kg milk/d, 624±62 kg BW) housed in a free stall barn (ISU Dairy) were blocked by parity, days in milk and previous milk production and randomly assigned to a control TMR or a TMR containing a blend of supplemental protease enzymes (4 g/cow/d; Rumagentin™, Feed Sources LLC, Alta Loma CA). The TMR consisted primarily of corn silage, alfalfa hay, dried distiller grains, and concentrate and did not contain supplemental by-pass protein. Cows were housed 24 to a pen (4 pens total) and thus pen was the experimental unit in a crossover design with two 21-d experimental periods. Two pens received the supplement during period 1 and the other two pens received the control. Pens then switched treatments during period 2 and there was a 7 d washout between periods. The 7 d immediately prior to period 1 were used as a covariate in the statistical analysis (repeated measures in the Proc Mixed procedure of SAS). Daily pen milk yield and DMI were recorded and milk composition from all cows was determined on d 15, 17, 19 and 21 of each period. All data was condensed into weekly means. There was no treatment effect on milk yield (37.6 kg/d), but supplemental enzyme-fed cows had less DMI (0.93 kg/d; P < 0.05) compared to controls and therefore tended (P = 0.08) to have improved (13%) feed efficiency (solids corrected milk/DMI). Protease treatment had no effect on milk fat (3.53%) or milk protein (3.24%), but tended (P = 0.08) to increase milk lactose (4.73 vs. 4.76%). Feeding supplemental enzymes tended (P = 0.10) to decrease milk urea nitrogen levels (15.1 vs. 14.6 mg/dl) but had no effect on milk SCC. Under these circumstances it appears that supplementing a proprietary blend of protease enzymes improves feed efficiency and may enhance feed nitrogen utilization in lactating dairy cows.

Protease enzymes, Feed efficiency

Feed intake

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