Effect of Two Stage Probiotic Supplementing as Monensin Replacement on High Producing Holstein Dairy Cows Performance

The objective of this study was to investigate the effects of probiotic in the midlactation of high yielding (47. 46 ± 6. 16 kg/d) dairy cows. This study was conducted by 56 lactating multiparous Holstein cows (96. 87 ± 32. 15 d in milk) in a randomized complete design with two treatments (probiotic and control). The program of using probiotic included: first period was from day 1 to 10 which each cow consumed 56 g of an combination named P-1 (priority one) /day، second period was from day 11 to 40 which each cow consumed 28 g P-One and 28 g of a combination named DCP (priority DCP) /day. Also، for similarity with commercial production، 300 mg/cow/d of monensin was used in control ration. Diets were fed grouping ad-libitum as total mixed ration with a concentrate to forage ratio of 64. 8:35. 2. These additives did not affect fiber and crude protein digestibility. Feeding probiotic increased propionate percentage (P<0. 05) and tended to decrease acetate: propionate ratio (P<0. 10). But rumen pH was not affected by treatments. Milk fat production was increased when probiotic was used (P<0. 05) but milk production and other milk components were unaffected by treatment. Under the conditions of this study، supplementing midlactation high producing cows with probiotic may improved rumen fermentation and some production parameters and can be replaced with monensin as feed additive.