Weaning age affects growth, feed intake, gastrointestinal development, and behavior in Holstein calves fed an elevated plane of nutrition during the preweaning stage
Bibliographic record
Abstract
Recent research has revealed potential advantages of feeding an elevated plane of nutrition to calves during the preweaning period. However, calves fed more nutrients preweaning may be more susceptible to depressed growth and weaning stress during the transition from liquid to solid feed. The objective of this study was to investigate the relationship between the age of weaning and feed intake, and its influence on growth, gastrointestinal development, and behavioral indicators in dairy calves fed an elevated plane of nutrition during the preweaning period. To meet this objective, 20 female Holstein calves were randomly assigned at birth to be weaned at 6 or 8 wk. Milk replacer (mixed at 150 g/L) was offered at 1.2 kg/calf per day in 2 meals until a 1-wk step-down, when meals were reduced by 50% 1 wk before weaning. Daily starter, chopped oat straw, water intake, and weekly body weights were measured until d 70 of life. To assess digestive tract development, rumen fluid, fecal, and blood samples were taken before and after weaning (d 35, 49, and 63) and analyzed for ruminal short-chain fatty acids, blood β-hydroxybutyrate, and fecal starch, respectively. Behavioral indicators of weaning stress, including vocalizing and non-nutritive oral behavior, were measured by visual observation for 1 h, 3 times per week, before the second feeding of the day during the period from 2 wk before weaning to 2 wk after weaning. The calves weaned at 8 wk compared with 6 wk had higher average daily gain for the week preweaning (0.79±0.09 vs. 0.34±0.10 kg/d) and postweaning (1.05±0.09 vs. 0.35±0.11 kg/d), and were heavier at d 70 (99.9±1.81 vs. 91.0±2.26 kg). From 5 to 8 wk of age, starter and water intakes were lower in calves weaned at 8 wk of age. However, overall starter intake did not differ during the last week of the experiment. Furthermore, calves weaned at 8 wk compared with 6 wk had higher starter intake for 1 wk preweaning (1.36±0.13 vs. 0.40±0.08 kg/d) and postweaning (2.51±0.20 vs. 1.16±0.15 kg/d). In both treatments, weaning increased ruminal short-chain fatty acids, blood β-hydroxybutyrate, and fecal starch, yet the differences between the week before and after weaning were greater for calves weaned at 6 wk compared with those weaned at 8 wk. Treatment × week relative to weaning interactions indicated that several behaviors varied between early- and later-weaned calves during the week before weaning; calves weaned at 6 wk tended to exhibit 75% more non-nutritive oral behavior and spent 55% less time ruminating, and 36% less time lying compared with calves weaned at 8 wk. Under the conditions of this study, the results suggest that calves fed an elevated plane of nutrition preweaning have higher starter intakes and average daily gain during the weaning period when weaning is extended from 6 to 8 wk of age.
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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) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| 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".