Effect of pre- and post-calving concentrate allocation and of starch source on feed intake, blood metabolite profiles and performance of transition cows

A two-factorial experiment was carried out on Polish Holstein-Friesian cows from the 6(th) week before parturition to the 12(th) week of lactation, allotted into 6 groups of 8 animals that before parturition and in the first week of lactation were fed rations differentiated in protein and energy levels. Animals of each group received two kinds of concentrate (1. 10-1.12 UFL/kg DM) containing barley (subgroup B) or maize (subgroup M) as the main source of energy. Cows from group I (control) were fed according to IZ-INRA (2001) standards before parturition and in early lactation. The level of concentrate in diets for every group was increased weekly either from week 3 before parturition to the first week of lactation (kg/day in week 3, 2, 1 before parturition and week I after parturition, respectively): in group I - 1, 2, 2, 4; group 11 - 1, 2, 4, 6; group III - 2, 2, 2, 4; group IV - 2, 2, 4, 6 or from week 6 before parturition to the first week of lactation (kg/day in week 6, 5, 4 3, 2, 1 before parturition and week I after parturition, respectively): group V - 2, 2, 2, 2, 2, 2, 4 and group VI - 2, 2, 2, 2, 2, 4, 6. Irrespective of starch source, cows of groups II, IV and VI receiving 2 kg of concentrates more than others, both in week I before parturition and in the first week of lactation, consumed more dry matter (P<0.01), which may suggest reduction of energy and protein deficits. Differences in the concentration of metabolites in blood serum did not differ significantly between the groups, but numerically higher values of non-esterified fatty acids, P-hydroxybutyric acid, glucose, insulin and aspartate aminotransferase in group VI, both before and after parturition, may suggest a beneficial influence of concentrate allocation method on energy balance. Milk yield did not differ among groups, although cows of group VI produced from 1.05 to 2.47 kg/day more than cows of other groups. The concentrate allocation method significantly affected (P<0.01) milk protein content, with the highest values for groups V and VI. On the other hand, the source of starch, irrespective of concentrate allocation method, did not influence dry matter intake or level of metabolites in blood serum. Cows fed rations containing barley produced 0.94 kg/day more milk than those fed concentrate with maize, but the differences were not statistically significant (P>0.05). The concentration allocation and starch source did not influence reproduction performance. The results of this study suggest that concentrate allocation, in particular, increasing the amount of concentrate provided in the last week of pregnancy and first week of lactation, may affect production and energy metabolism of transition cows. Extension of concentrate feeding to 6 weeks before parturition may additionally improve energy balance. The source of starch plays no important role.