Energy efficiency of diet for periparturient dairy cows supplemented with free fatty acids or glucogenic additives

The aim of the study was to compare the efficiency of two energy preparations used at fixed doses, but for different lengths of time: 1) a loose mixture of propylene glycol and sodium propionate, and 2) a granular formulation of free fatty acids produced from palm oil and palm nut, non-degradable in the rumen. A three-factorial experiment was carried out on 5 groups of Polish Black and White Holstein-Friesian cows (10 animals each) which were within the transition period. The aim of the experiment was to determine the effect of two energy preparations administered at a constant dose, but over different time periods, on the animals' performance, as well as on their milk yield and composition. The following treatment groups were formed: control group C, which received a standard diet; experimental groups G1 and G2, which received a dietary additive of a glucogenic preparation; and experimental groups F1 and F2, which received a free fatty acid preparation. The diet of the transition cows was supplemented with the full dose of the additives (500 g/head/day) for 2 weeks before the expected calving and 3 or 6 weeks of lactation. The present research confirmed the benefits of dietary inclusion of energy supplements for transition cows. Supplementation with both glucogenic and free fatty acid preparations reduced the negative energy balance in the cow's organism and improved milk production and composition. The milk yield, higher by ca. 10% for the cows fed diets with energy additives (relative to the control treatment), provides evidence of a substantial beneficial effect of supplemental dietary energy on the efficiency of cow milk production. In the present study, the best basic milk composition was obtained in the cows receiving a dietary addition of the glucogenic preparation at a dose of 500 g/head/day until the end of the 6(th) lactation week. The animals from this group also had the highest milk yield evaluated for 305 days. In order to improve the energy balance in high-yielding transition cows, it is recommended that dairy managers apply feed energy additives based on propylene glycol and sodium propionate.