254 In vitro evaluation of short-season corn silage hybrids grown in central and southern Alberta, Canada, and harvested before or after frost: Nutrient content, degradability and enteric methane emission
Bibliographic record
Abstract
The objective of this study was to characterize the nutritive value of short-season corn silage (CS) hybrids (rated at ≤2600 corn heat units (CHU) for grain maturity) and examine their in vitro rumen fermentation and CH4 emission (batch culture; 2 runs, 3 replicates/run). Four CS hybrids were grown in 2 years in Central (Lacombe; hybrids: 39F44, 39M26, P7632HR, PS2262RR; 2000–2200 CHU rating) or Southern (Vauxhall; hybrids: P7632HR, P8210HR, P8622AM, P8673AM; 2200–2600 CHU rating) Alberta and harvested before or after slight frost to increase dry matter (DM) concentration. Hybrids grown at each location were selected based on having a CHU rating suitable for the location. Starch content was greater (P < 0.05) for hybrids grown in Southern compared with Central AB (27.8 vs. 22.0% DM) and for hybrids harvested after frost (26.4 vs. 23.4% DM). The NDF content did not differ between locations (mean 53.2%; P > 0.05) but was decreased after frost in Southern hybrids (50.4 vs. 55.0; location × harvest, P = 0.04). Similarly, DMD did not differ between locations (mean 58.7%; P = 0.11) but was increased after frost for Southern hybrids (59.9 vs. 56.5%; location × harvest, P < 0.001). The NDF degradability (NDFD) was greater for Central versus Southern hybrids (39.8 vs 37.5%, P < 0.001) but was increased after frost for Southern hybrids (40.0 vs. 36.0%; location × harvest, P < 0.001). Total VFA concentration in vitro was greater for Central than Southern hybrids (40.2 vs. 37.8 mM), and it increased after frost for Southern hybrids (39.7 vs. 35.9 mM; location × harvest, P = 0.01). The proportion of propionate (mol/100 mol) was greater (P < 0.01) for Southern hybrids (30.7 vs. 29.5) and those harvested after frost (31.0 vs. 29.3). Harvesting before frost tended (location × harvest, P = 0.08) to increase CH4 (mL/g digested DM) for Central (28.2 vs. 27.0) but not Southern hybrids (mean 25.8). Methane production was inversely correlated with propionate proportion (r = -0.64; P < 0.05). Greater starch content of Southern versus Central hybrids corresponded to lower CH4 emissions through its impact on propionate. DMD was not affected by location because Southern hybrids had higher starch content but Central hybrids had greater NDFD. Harvesting Southern hybrids after frost increased DMD and thus has the potential to improve animal performance while lowering CH4 emissions. Although harvesting Central hybrids after frost had limited effects on degradability, it tended to reduce CH4 emissions.
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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 | 0.000 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 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".