Effects of feeding strategy and duration of the dry period on the rumen microbiota of dairy cows

Abstract

The composition of rumen microbiota during late gestation and early lactation was compared between cows receiving a close-up diet (1.43 Mcal net energy of lactation (NEl) kg−1 dry matter (DM)) throughout a 40 d dry period (SHORT) and cows receiving a far-off diet (1.28 Mcal NEl kg−1 DM) as well as the close-up diet (as above) for 39 and 21 d, respectively, during a conventional 60 d dry period (CONV). Rumen fluid was collected at weeks −2, −1, +1, +2, and +7 relative to calving. Extracted DNA was analyzed for taxonomic composition of the rumen microbiome using MiSeq Illumina sequencing of the V4 region of the 16S rRNA gene. At week +1, this composition differed (P < 0.05) between treatments. In cows under the CONV treatment, this composition only differed (P < 0.05) between weeks −1 and +1. For SHORT cows, this composition tended to differ between weeks +1 and +2 (P = 0.09) as well as between weeks +2 and +7 (P < 0.03). The change of the taxonomic composition of the rumen microbiota after calving, mainly consisting of increases in the abundance of Firmicutes and decreases in that of Bacteroidites, was comparatively slower and less favourable under the SHORT treatment. This may have been due to more excessive grain intake before calving of cows on the latter treatment.