Effects of organic acid-based products added to total mixed ration on performance and ruminal fermentation of dairy cows

An increase in total mixed ration (TMR) temperature is associated with a growth of undesirable microorganisms and decreases in feed intake in dairy cows. We evaluated the effects preservative products containing organic acids (OA) added to TMR on intake and digestibility of nutrients, rumen fermentation, milk yield and composition, nitrogen utilization, blood parameters, ingestive behavior of cows. Twenty-five Holstein cows (147.4 +/- 87.9 days in milk, 668.7 +/- 78.5 kg of body weight and 34.4 +/- 4.2 kg/d milk yield), 10 of which were rumencannulated, were assigned to a 5 x 5 Latin square experiment containing the following treatments: control (CON), no OA added to TMR; and four preservatives composed mainly of either formic acid (FLE), sodium formate (SOL), propionic acid (SPE) in liquid form, or propionic acid (PER) in solid form added to TMR. The OA products used in this study were manufactured by Perstorp Waspik BV (Waspik, The Netherlands). Products were added daily to the TMR at 4 ml/kg natural matter (NM) for the liquid products (FLE, SPE, PER), and at 4 g/kg for the solid product (SOL). The experimental barn temperature, relative humidity, and temperature-humidity index during the experiment were 24.4 +/- 4.29 degrees C, 75.0 +/- 16.39%, and 72.7 +/- 5.31 (mean +/- SD), respectively. Each experimental period consisted of 14 days for adaptation to treatments and five days for sampling. Differences among treatments were studied using orthogonal contrasts, as follows: the effect of OA {[}control versus OA (SPE + SOL + PER + FLE)], the effect of OA composition {[}formic acid (FLE + SOL) versus propionic acid (PER + SPE)], the effect of different formic acid products (FLE versus SOL); and the effect of different propionic acid products (SPE versus PER). Organic acids increased feed intake (23.6 and 24.4 kg/d for CON and OA, respectively) and reduced sorting of feed particles with 8-19 mm size and shorter than 4 mm. Organic acids, however, decreased the total VFA concentration and increased pH of rumen fluid. Cows fed TMR with OA had greater fat-corrected milk production and milk protein content compared with CON. Organic acids avoided an increase in TMR temperature within 24 h air exposure. Organic acids, regardless of their composition, can maintain TMR temperature stable for longer periods and improve the performance of dairy cows. (AU)