Effects of effective microorganism supplementation on behavioural patterns, stress markers and haematological parameters of lactating dairy cows

This study evaluated the effects of effective microorganism (EM) supplementation on feeding and drinking behavior, stress markers, physiological responses, udder health, and hematological parameters in lactating dairy cows. Ten Jersey crossbred cows (body weight = 403.78 ± 58.57 kg) of the same parity were randomly assigned to either a control group or an EM-supplemented group (10 mL kg^-1 TMR) in a completely randomized design over a 12-week feeding trial. Behavioral observations and sample collections commenced eight weeks after trial initiation. Feeding and drinking behaviors were recorded using a CCTV camera and analyzed using BORIS software. Rectal temperature, heart rate, rumen motility, and udder health parameters were monitored weekly, while agonistic behaviors were recorded during the cows’ resting periods. Blood samples were collected from the jugular vein of each cow before trial initiation and on the final day of the feeding trial. Data were analyzed using the MIXED procedure in SAS software. Results revealed that EM-treated cows exhibited significantly (p<0.05) higher frequencies of feeding and drinking behaviors (4.51 ± 0.34 and 1.82  ± 0.31 events 2h^-1, respectively) compared with the control group (2.31±0.34 and 1.02±0.31 events 2h^-1, respectively). Allo-grooming (licking other cows) was significantly (p<0.05) higher in the EM-supplemented group ( 1.60 ± 0.42 events 2h^-1 ) than in the control group (1.65 ± 0.42 events 2h^-1 ), whereas other social interactions remained unaffected. Rumen movements were significantly (p<0.05) lower in EM-treated cows (3.31 ± 0.13 contractions min^-1) compared with the control group (4.08 ± 0.13 contractions min^-1), while rectal temperature and heart rate did not differ between treatments (p<0.05). The incidence of mastitis and stress markers did not differ significantly between treatment groups (p<0.05), and hematological parameters remained within standard reference ranges. In conclusion, dietary EM supplementation positively influences ingestive and social behaviors while maintaining stable physiological and health indices in lactating cows, highlighting its potential as a beneficial feed additive.