Effects of monensin on production and energy metabolism in early lactation cows
Keywords: cows, monensin, BHB, glucose, production
AbstractThe aim of the research was to investigate effects of monensin controlled-release capsules on production and metabolism in early lactation cows, with relation to the time of administration of monensin. The study was performed in 2014 (from 01/05/2014 to 01/10/2014) at a Lithuanian cattle farm having 500 dairy cows. Four experimental groups were applied as follows: 1) Group 1 (G1) control (no supplementation, n = 20); 2) Group 2 (G2) with supplementation of monensin (32.4 g monensin controlled-release capsule (MCRC), n = 20). Both groups were on 30th day before expected calving; 3) Group 3 (G3) control (no supplementation, n = 10); 4) Group 4 (G4) with supplementation of monensin (32.4 g monensin controlled-release capsule (MCRC), n = 10). Both groups were on day 1 post partum. Group 2 (G2) received MCRC 30 days before calving, Group 4 (G4) 1 day after calving. Experimental and control cows received the same diet and were exposed to the same environment and management conditions during the entire experimental protocol. Blood samples were collected from the coccygeal vessels: G1 and G2 cows from day –30 (before expected calving, prior to supplementation), each day, up to 30 days post partum; G3 and G4 from day 1 post partum, each day, up to 30 days post partum. Blood serum was tested for beta-hydroxybutyrates (BHB) and glucose concentration. The daily milk yield was measured electronically (DairyPlan C21, Westfalia Surge Inc., GEA). Milk was sampled once monthly. Samples were analyzed for contents of fat, protein, lactose, urea, and somatic cells count. The BHB concentration decreased more efficiently after the supplementation of MCRC after calving. After supplementation with monensin on the first day after calving, it has been identified that the BHB concentration in serum of experimental group (G4) cows statistically significantly decreased after 3 days (p < 0.05). During this period, the average BHB concentration of control group (G3) cows was 0.414 (±0.05) mmol/l, while the BHB concentration of experimental group (G4) cows was 0.27 (±0.03) mmol/l. Statistically significant differences between the experimental and the control groups were observed during the entire study (p < 0.05). After calving, cows supplemented with monensin showed statistically significant higher production of milk (p < 0.05) than the control group. Statistically significant differences in the blood glucose and BHB concentration, quantity of milk and production average between two experimental groups (G2 and G4) were not identified.