Effect of wheat- or oat-straw inclusion with wheat bran or corn grain in prepartum diets on postpartum performance of transition dairy cows

Current study evaluated the effects of feeding straw source and energy supplementation during prepartum period on postpartum production performance and changes in blood metabolites of crossbred dairy cows. Twenty-eight crossbred (Holstein × Sahiwal) cows were randomly assigned to one of the following four dietary treatments: (1) wheat straw and corn grain (WSCG), (2) wheat straw and wheat bran (WSWB), (3) oat straw and corn grain (OSCG) and (4) oat straw and wheat bran (OSWB) in a 2 × 2 factorial experiment. Iso-nitrogenous diets fed as ad libitum total mixed ration contained 25% wheat straw (WS) or oat straw (OS) and 10% corn grain (CG) or wheat bran (WB). Experimental duration was 42 days before and 56 days after calving. After calving, all animals were fed a similar lactation diet. Pre- and postpartum dry-matter intake % of BW was not affected by treatments. Prepartum energy balance (EBAL) was higher for OS than WS and higher for CG than WB animals. Postpartum EBAL was higher in the WSCG than OSCG treatment. Milk production and composition were not affected by straw source or energy concentrate. Milk yield at Weeks 1, 2 and 3 was higher in the WSWB than WSCG and OSWB treatments. Total solids and feed efficiency were higher in the WSWB than WSCG treatment. Postpartum plasma concentration of non-esterified fatty acids was higher in the WS than the OS diet; however, the measured values were within normal limits. Postpartum plasma β-hydroxybutyrate concentration was not affected by straw source or energy concentrate. Cows fed WSWB prepartum were in positive EBAL, before and after calving, closer to the recommended requirements. Moreover, cows fed WSWB had a lower incidence of health disorders and subclinical ketosis, higher milk production and better feed conversion efficiency during first 3 weeks after calving.