Effect of chromium methionine and energy source on production and nutrient digestibility of Holstein cows in prepartum and postpartum

In this study، 32 multiparous non lactating Holstein cows were used to investigate the effects of chromium-l-methionine (Cr-Met) supplementation and dietary energy source on production and nutrient digestibility during the periparturient period. Cows were fed a total mixed ration from 28 days before anticipated calving through 28 days after calving. The study was designed as a randomized complete block design with 2 (energy sources) × 2 (Cr-Met levels) factorial arrangement. Energy sources in the prepartum were fish oil and grain، and were fish oil and palm fat powder in the postpartum. The Cr-Met was supplemented at dosages of 0 or 0. 08 mg of Cr/kg of metabolic body weight. Fish oil Supplementation had no significant effect on prepartum dry matter intake (DMI) but tended to decrease postpartum DMI (P< 0. 1). Supplemental Cr-Met increased prepartum and postpartum DMI significantly (P<0. 05). The effect of treatments on milk production was not significant. No differences were detected in milk composition except for fat percentage in which cows were fed the fish oil had lower percentage of fat compare to others. Supplemental Cr-Met had no significant effect on nutrient digestibility in the prepartum and postpartum. Use of fish oil had no effect on nutrient digestibility in the prepartum، but decreased digestibility of dry matter، organic matter، and crude protein in the postpartum (P<0. 05). Results of this study indicate no significant interaction between chromium supplementation and energy source.