Effects of protected fat supplements on production of early lactation Holstein cows

This study was conducted to evaluate production response of early lactating cows to rumen protected fat. Twelve Holstein cows (26 ± 4 days in milk) were used in a replicated 3 × 3 Latin square design with 21-day experimental period and three treatments: control (no fat supplementation), and supplemented with 30 g/kg prilled protected fat (Energizer-10) or 35 g/kg Ca salt of protected fat (Magnapac). Cows were fed ad libitum a total mixed ration consisting of 200 g/kg corn silage, 200 g/kg alfalfa hay and 600 g/kg concentrate mix. Each period had 14 days of adaptation and 7 days for sampling. Intakes of dry matter (DM), organic matter (OM) and neutral detergent fibre (NDF) were decreased with supplementation of rumen protected fat in cows (P<0.05). Production of milk and energy corrected milk (ECM), composition and yield of milk fat, protein and lactose were not affected (P>0.05) by fat supplements in cows. As a result, milk efficiency (ECM/DM intake) was improved from 1.35 for control to 1.47 and 1.44 with supplementation of Energizer-10 and Magnapac, respectively (P<0.01). Feeding fat supplements increased ruminating time. Body condition score and body weight changes were similar among the treatments in all cows. These results indicate that supplementation of early lactating diet with rumen protected fat decreased feed intake but without altering milk production, milk composition and body weight, thus improved milk efficiency.