effects of monensin and propylene glycol on milk production, milk composition and some blood metabolites in holstein lactating cows

the effects of monesin and propylene glycol on feed intake, milk production, and composition as well as some blood metabolites of 16 primiparous and multiparous holstein lactating cows (60±30 days in milk (dim), milk production of 33±3 kg/day) were evaluated. cows were experimentally in a arranged in a randomized complete block design of: 4 feeding treatments, and 2 blocks of either primiparous or multiparous. they were fed a balanced total mixed ration of 60% concentrate and 40% forages (with or without additives). cows in group i were fed total ixed ration (tmr) with no additives (control). cows in group ? were fed tmr with 335 mg/head/day monensin. cows in group ? were fed tmr with 400 ml/head/day of propylene glycol, and finally cows in group iv were fed tmr with 335 mg/head/day of monensin and 400 ml/head/day of propylene glycol. daily milk yield, milk composition and some blood metabolites were recorded. data were analyzed using mixed models for repeated measurements. the experimental treatments did not affect either feed intake or milk composition, but propylene glycol caused significant increase in cows' milk yield (p