| Abstrakt: |
The objective of this study was to investigate the impact of incremental amounts of ground flaxseed (GFX) on ruminal microbiota of lactating Jersey cows. Twelve lactating organically-certified Jersey cows (76 ± 23 DIM and 431 ± 25 kg of BW), part of a larger feeding trial, were used in a replicated 4 × 4 Latin square design with 21-d periods (14 d for diet adaptation and 7 d for sample collection). Cows were randomly assigned to 1 of 4 treatments (DM basis) consisted of 55% mixed-mostly grass silage, 8% mixed-mostly grass hay, 2% roasted soybean and: 1) 0% GFX, 6% soybean meal (SBM), and 27% corn meal (CM), 2) 5% GFX, 4.8% SBM, and 23.2% CM, 3) 10% GFX, 3.5% SBM, and 19.5% CM, and 4) 15% GFX, 2% SBM, and 16% CM. Ruminal fluid was sampled using an esophageal tube 7 h after the morning feeding on d 17 to 19 of each experimental period, pooled, and frozen at −80°C until analysis. After DNA extraction, the 16S rRNA gene V4 variable region PCR primers 515/806 were used. Following amplification, PCR products were pooled in equal proportions based on their molecular weight and DNA concentration, purified using calibrated Ampure XP beads, and then used to prepare the DNA library for Illumina TruSeq DNA analysis (Mr. DNA Molecular Research Laboratory, Shallowater, TX). Sequencing was performed on a MiSeq and data were processed using a proprietary analysis pipeline. Final operational taxonomical units were classified using BLASTn against a curated database derived from GreenGenes, RDPII, and NCBI. Orthogonal polynomial contrasts were used to test linear and quadratic effects. Results are shown in Table 1. The ruminal proportion of archaea responded quadratically to feeding GFX. Specifically, the proportion of Methanobrevibactersp. and Methanosphaerasp. responded quadratically, whereas that of Methanomicrobiumsp. decreased linearly with the greatest level of GFX resulting in the lowest values. Quadratic effects were also observed for Fibrobactersp. and Prevotellasp. with feeding GFX. Whereas the 3 major ruminal cellulolytic species (Fibrobacter succinogenes, Ruminococcus albus, and Ruminococcus flavefasciens) were not affected by GFX supplementation, the ruminal proportion of Prevotella ruminicolaand Prevotella briantiiresponded quadratically with greatest values found when feeding 15% GFX. Overall, feeding incremental amounts of GFX to lactating dairy cows decreased the ruminal proportion of methanogens, but did not affect the 3 major species of ruminal cellulolytic bacteria.Table 1637. |
