Effect of monensin and essential oils on performance and energy metabolism of transition dairy cows.

Abstract

This work examined preventive effects of a dietary and a medical intervention measure on postpartum (p.p.) ketogenesis in dairy cows overconditioned in late pregnancy. Sixty German Holstein cows were allocated 6weeks antepartum (a.p.) to three high body condition score (BCS) groups (BCS 3.95±0.08) and one low BCS group (LC, BCS 2.77±0.14). Concentrate proportion in diet a.p. was higher (60% vs. 20%) and increase in proportion p.p. from 30% up to 50% decelerated (3 vs. 2weeks) in high BCS groups. High BCS cows received a monensin controlled-release capsule (CRC) (HC/MO), a blend of essential oils (HC/EO) or formed a control group (HC). Performance parameters and energy status were evaluated in three periods [day (d) -42 until calving, one until 14days in milk (DIM), 15 until 56 DIM]. Feed efficiency was 65% and 53% higher in HC/MO than in LC (p<0.001) and HC groups (p=0.002) in the second period. Milk fat content was higher in HC/EO (5.60 vs. 4.82%; p=0.012) and milk urea higher in HC/MO (135mg/kg) than in LC cows (107mg/kg; p<0.001). Increased p.p. levels of non-esterified fatty acids in serum were found in HC (p=0.003), HC/MO (p=0.068) and HC/EO (p=0.002) in comparison with LC cows. Prevalence of subclinical and clinical ketosis was 54% and 46%, respectively, in HC group. Monensin decreased the prevalence to 50% and 7% respectively. Ruminal fermentation pattern showed higher proportions of propionate (23.43mol % and 17.75mol %, respectively; p<0.008) and lower acetate:propionate ratio (2.66 vs. 3.76; p<0.001) in HC/MO than HC group. Results suggest that a monensin CRC improved energy status and feed efficiency of transition dairy cows while essential oils failed to elicit any effect.