Determining methionine and cysteine requirements of male and female Ross 708 broilers exposed to heat stress during the finisher period
Bibliographic record
Abstract
This study aimed to determine standard ileal digestible methionine and cysteine (dig Met+Cys) requirements of broilers reared under cyclic heat stress conditions. A basal diet deficient in dig Met+Cys was used as a control (0.254 % dig Met, 0.240 % dig Cys), and supplemented with DL-Methionine at 5 graded levels (0.050, 0.090, 0.170, 0.290, and 0.450 %), replacing silicon dioxide for six treatments containing 0.494, 0.541, 0.588, 0.648, 0.738, and 0.837 % dig Met+Cys, was fed from d 20 to 33. Day-old Ross 708 chicks were sex separated and housed in nine rooms (five male, four female), each containing 6 trial pens. From d 27 to 33, the birds were exposed to cyclical heat stress, alternating between a 12-h exposure to 31 °C and a 12-h cool period of 21 °C (minimum humidity 50 %; humidex of 41 °C and 23 °C). Body and feed weights were measured on d 0, 20, 27, and 33. On d 31, 1 bird per pen was euthanized and had a breast and liver sample taken to measure biomarkers for oxidative damage and antioxidant capacity. On d 34, 3 birds per pen were slaughtered and used to measure meat yield. Data were analyzed as a one-way ANOVA using the MIXED procedure in SAS and using an exponential regression model to determine requirements. Increasing dietary dig Met+Cys significantly improved BW gain and feed-to-gain (F:G). The estimated required dig Met+Cys intake to maximize BW gain and F:G for males were 0.976 g/d and 1.116 g/d, respectively, and 1.031 g/d for females for both parameters. No significant effects of dig Met+Cys level on antioxidant activity were observed. Requirements for maximal Pectoralis major yields were approximately 0.808 and 0.726 g/d dig Met+Cys intake for males and females, respectively. Based on F:G response, a daily intake of dig Met+Cys of 1.116 g (males) and 1.031 g (females) for Ross 708 broilers under cyclical heat stress conditions of 31 °C and 21 °C from d 27 to 33 is required, while meeting needs for optimal BWG and meat yield.
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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 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 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".