Addition of organic acids in the diet of dairy cows

Increased feed temperature is associated with growth of unwanted microrganisms, nutrient losses, and decreased feed consumption by dairy cows. We evaluated the use of preservative products containing organic acids (OA) in TMR on intake and total tract apparent digestibility of nutrients, feed particle size sorting, ruminal fermentation, milk yield and composition, nitrogen balance, microbial protein synthesis, metabolic profile, ingestive behavior, and TMR temperature. Twenty-five Holstein cows, 10 of them rumen-cannulated, were assigned to a 5 × 5 Latin square experiment with treatment sequences containing the following: control, without additives in the diet (CON); or addition of four distinct products that had as main active principles: formic acid (F); sodium formate (SO); propionic acid (SP); and propionic acid (P). Each OA was added daily to the TMR at the dose of 4 mL/kg natural matter offered for the liquid products, and 4 g/kg for solid product. The average temperature of the experimental barn, relative humidity, and temperature-humidity index during the experiment were 24.4 ± 4.29 °C, 75.0 ± 16.39 %, and 72.7 ± 5.31 (mean ± SD), respectively. Each experimental period consisted of 14 days for treatment adaptation and 5 days of sampling. Differences among treatments were studied using orthogonal contrasts as follows: effect of the addition of OA [control versus treatments (SP + SO + P + F)], effect of type of OA used [formic acid (F + SO) versus propionic acid (P + SP)], effect of the addition of formic acid way (F versus SO), and effect of addition of propionic acid way (SP versus P). Organic acids increased feed intake (23.6 and 24.4 kg/d for CON and OA, respectively) and reduced sorting of feed particles between 8-19 mm and shorter than 4 mm. Organic acids, however, decreased total VFA concentration and pH in the rumen fluid. Cows fed TMRs with OA had greater fat-corrected milk production and milk protein content compared with control. Furthermore, OA delayed the raise in TMR temperature. Organic acids, regardless of their composition, may improve the performance of dairy cows. (AU)