Impact of a mixed culture of <i>Lactobacillus casei</i> and <i>L. lactis</i> on in vitro ruminal fermentation and the growth of feedlot steers fed barley-based diets
Bibliographic record
Abstract
The effect of a direct-fed microbial (DFM) poduct containing a mixed culture of Lactobacillus casei and L. lactis on in vitro ruminal fermentation of barley-grain/barley-silage-based backgrounding and finishing diets and on growth performance and carcass characteristics of feedlot cattle was evaluated during backgrounding (84 d) and finishing (140 d) of 100 Hereford × Angus steers (initial body weight = 280 ± 15.5 kg). The inclusion rates of DFM in the in vitro study were 4, 8, 12 and 16 million colony forming units (CFU) of lactic acid bacteria (LAB) kg-1 DM of substrate. Total in vitro volatile fatty acids (VFA) production increased at 6 and 12 h of incubation (P < 0.01; linear response) when the backgrounding diet was supplemented with DFM. Dry matter digestibility and VFA production also increased (P < 0.05) during a 12-h fermentation of the finishing diet. Steers were randomly allocated to one of four dietary treatments that comprised feeding DFM tp provide 0 (control), 4 × 107, 8 × 107, or 12 × 107 CFU kg-1 diet DM. Average daily gain (ADG, kg) and feed efficiency (G:F; kg gain kg-1 DM consumed) of steers improved (P = 0.002 and 0.001, respectively) as a result of feeding DFM during the backgrounding period, but not during the finishing period. Saleable meat and rib eye area decreased (P = 0.038, linear; and P = 0.041, quadratic) with DFM supplementation. The results indicated that supplementing barley-grain/barley-silage-based feedlot cattle diets with 12 × 107 CFU of the mixed culture of lactobacilli used in these studies could improve ruminal fermentation, ADG and G:F in backgrounding feedlot steers. However, supplementation during the finishing period may not be warranted in terms of growth performance and carcass characteristics. Differences in the microbial ecology of the intestinal tract as a result of differences in diet composition may account for the varied response between the backgrounding and finishing periods.Key words: Beef cattle, direct-fed microbial, growth performance, Lactobacillus casei, Lactobacillus lactis, ruminal fermentation
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.001 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".