FACTORS AFFECTING THE VITAMIN A AND ß-CAROTENE CONTENTS OF MILK
Bibliographic record
Abstract
The factors affecting the vitamin A and s-carotene contents of milk were investigated. A series of short- and long-term experiments were conducted using the University of Saskatchewan dairy herd and Saskatoon commercial fluid milk, respectively. The vitamin A potency of the milk was significantly influenced by cow-to-cow variations when the experimental cows were receiving high levels (87,600 IU/kg feed) of vitamin A supplementation. The day-to-day variations significantly affected the vitamin A content of milk when early lactation cows received low levels (8,200 IU/kg feed) of vitamin A supplementation. The milk of cows in late lactation contained more vitamin A per 100 ml but the milk of cows in early lactation contained more vitamin A per gm butter fat. Pronounced seasonal variations were observed in Saskatoon market milks. The spring milk contained 28.87%, 20.09%, and 8.33% more vitamin A potency than that of winter, fall and summer milk, respectively. Overall, spring and summer milk had significantly more vitamin A (1.17 times) than that of winter and fall milk. Supplementation of feeds with about 10 times the RDA of vitamin A increased the vitamin A content of the milk by 24% but did not affect either the milk yield or the B.F.% of the milk. Dietary hay suppressed, but dietary silage promoted, the recovery of dietary vitamin A in milk of cows fed the above forages, each supplemented with 250,000 and 600,000 IU vitamin A/cow/day. High levels of vitamin A intake depressed the milk and blood levels of s-carotene. Dietary levels of the vitamin A did not affect the concentration of the vitamin in the blood of the experimental animals. Pasteurization of milk had no deleterious effects on the vitamin A potency of milk. Skimming significantly reduced the vitamin A content of whole milk by 85.0% and 26.5% for skim and 2% B.F. milk, respectively. Fortification, at the processing plant, increased the vitamin A content of the low fat milk to above average levels. Maximal photodegradation of vitamin A occurred between 340 to 440 nm. s-carotene significantly protected vitamin A from photodegradation. Storage stability of vitamin A in processed milks (skim, 2% B.F. and homogenized milk) was found to be much less than that of whole, raw milk. The results from the study indicated that the vitamin A potency of milk can be optimized by fortification of winter feeds, particularly silage, with vitamin A. Once the milk has been produced, the vitamin A levels can be optimized by proper fortification of low fat milk and by proper packaging and storage of processed milk.
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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 | 0.001 | 0.001 |
| 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 | 0.001 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 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".