Effect of arginine:lysine and methionine source on amino acid digestibility and response to dietary electrolytes in chronically or acutely heat-stressed broilers
Bibliographic record
Abstract
In two experiments, the effects of arginine:lysine, NaHCO3 and methionine source on performance and amino acid digestion of heat-stressed broilers were studied. In exp. 1, corn/soy diets with argine:lysine (Arg:Lys) of 1.10, 1.25 and 1.40 were fed from 21 to 42 d. Diets were supplemented with 2-hydroxy-4-(methylthio)-butanoic acid (HMB) or DL-Methionine (DLM) with NaHCO3 at 0 or 1.04%. Ten replicates per treatment of four birds per cage were maintained at 31.7 ± 0.9°C. From 21 to 28 d weight gain (BWG), feed consumption and feed-to-gain (FCR) were unaffected by diet treatment. Methionine source did not influence bird performance (P > 0.05). However, from 35 to 42 d, when diets were supplemented with NaHCO3, BWG and FCR of birds fed DLM were compromised when offered diets with Arg:Lys at 1.40. In diets devoid of NaHCO3, increasing Arg:Lys to 1.25 impaired BWG and FCR for broilers fed DLM, although effects disappeared when more Arg was used. Performance of birds on HMB was mostly unaffected by Arg:Lys or NaHCO3 except when fed diets void of NaHCO3 with Arg:Lys of 1.40, when FCR was impaired. In exp. 2, broilers were maintained at thermoneutrality (TN) reaching 20°C at 33 d. Other birds were at 31°C throughout, representing chronic heat stress (CHS), while a third group changed suddenly from 20 to 31°C at 25 d representing acute heat stress (AHS). Birds within each environment were housed in one of two rooms with eight replicates of four birds per treatment. At 25 d, birds were fed Arg:Lys of 0.95 or 1.40 with DLM supplemented at requirement. Birds fed Arg:Lys of 1.40 were also offered diets with synthetic L-methionine (L-Met). Adding L-Met to high Arg diets during CHS significantly depressed ileal digestibility of all amino acids (P < 0.05). It is concluded that chronic heat stress can affect the digestibility of amino acids, and that this effect may impact performance. Key words: Broilers, methionine, arginine, heat stress, digestibility, sodium bicarbonate
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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 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.001 | 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".