The impact of low-nutrient and conventional diets on lameness, tibial dimensions and tibia ash concentrations for two fast-growing genotypes of broiler chickens
Bibliographic record
Abstract
Lameness is a critical welfare issue for the broiler industry, with fast growth being a causal factor.Diets may play an important role in both growth rates and lameness.Therefore, this study evaluated the impact of 2 diets (low-nutrient and conventional diet) on lameness, tibial dimensions, weight, ash concentration, and body weight (BW) in 2 commercial lines of broiler chickens.A total of 624 mixed sex birds from 2 fast-growing strains (A and B) of broiler chickens were placed in 24 pens (26 birds/pen; 23.23 kg bird/m2) and fed either a conventional (CV) or a low nutrient (LN) diet (n = 156).The LN diet had approximately 2% lower CP level compared with the CV diet throughout the trial.From each pen, 12 birds were wing-banded and followed from hatch.Individual BW was determined biweekly.On d 28, 4 wing-banded birds/pen (sentinel birds, n = 96) were chosen based on BW.On d 42, a latency to lie test (a validated method to assess lameness in broiler chickens, with lameness being associated with a reduced latency to lie in shallow water) was performed on sentinel birds.Birds were slaughtered on d 46 (BW = 3.22 0.076 kg) and both right and left tibia from sentinel birds were removed to determine tibial length, diameter, and tibial fresh weight (total and relative to BW).Bone ash concentration (%) was measured in the left tibia to estimate bone mineralization and composition.Data were analyzed as a complete randomized design with a 2 2 factorial arrangement with strains (A and B) and diets (LN and CV) as main factors and with final BW as a covariate, using Proc Glimmix in SAS.No interactions between diet and strain were observed for any parameter evaluated (P > 0.05).There was an effect of strain on BW at d 14 (P < 0.0001), d 28 (P < 0.0001) and d 42 (P < 0.0001), with heavier BW observed in strain A compared with strain B (248 g difference at d 42).Diet only affected BW at d 42 (P = 0.01).Birds fed CV diet were 119 g heavier than birds fed the LN diet.Latency to lie was not affected by diet (P = 0.84) or strain (P = 0.40).Tibial length was not affected by strain (P = 0.08) or diet (P = 0.09).However, birds fed the CV diet had a greater tibia diameter compared with the LN diet (P = 0.04).Consistently, tibial fresh weight (P = 0.02) and tibial fresh weight:BW ratio (P = 0.01) were greater for the CV-fed group.Tibial ash concentrations were not affected by strain (P = 0.43) or diet (P = 0.52).Strain influenced BW, but did not affect tibial morphology or lameness.Diet density affected BW at d 42, tibial diameter and weight, but not lameness.Further studies should investigate if slower growing strains of broilers have improved leg health and welfare.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| 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 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 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 teacher head, 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".