Peer review

Experiment was conducted with 36 dairy cows (in II-VI lactation), divided as analogues to three groups per 12 weeks (3 weeks before calving to 0 day – day of calving and second period first 70 days of lactation): group I – without glycerin supplement, group II – 300 ml·head-1·day-1 and III – 500 ml·head-1·day-1 supplemented to daily feed ration. All cows were fed two kinds of TMR, according to DLG requirements for each physiological phases: for dry period and for the first 100 days of lactation. The body condition, feed intake, milk production, milk chemical composition and main blood metabolites as glucose, BHB, NEFA were analyzed in experimental period. Total milk production or mean daily milk yield in group II and III was higher in 10 weeks of lactation in comparison to control group about 14.6 and 12.5% respectively. With increase dose of glycerin the protein level in milk was increased (P<0.05). In group III in 3rd week of lactation the concentration of BHB in blood serum was higher but glucose lower in comparison to other groups. The concentration of NEFA in blood serum in group III in 1st and 3rd weeks of lactation and in group II in 3rd week after calving was lower in comparison to control (I) group. The feed intake (in DM) of TMR was better in both groups with supplemented glycerin in comparison to control, especially between 4. and 9. week of lactation (P<0.05). At 70 days in cows fed TMR with glycerin better body score condition index was observed in comparison to control (P<0.05).

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