Comparative analysis of milk productivity traits of Holstein cows sired by bulls from different countries of origin
Bibliographic record
Abstract
An assessment of the effect of the countries of origin (CO) of bulls on the indicators of milk productivity of daughter cows during the first and higher lactations was carried out in the conditions of the breeding plant PLAE “Ukraine” of the Lutsk district of the Volyn region. The research material was data on zootechnical and breeding registration of cows, borrowed from the electronic information database of the DFMS “Intesel Orsek” as of September 2024. The CO of the sires was determined by the first two letters of the identification number, as well as the numbers of their fathers and mothers. Based on the CO of the breeding bull from the general population (N = 1275), experimental groups of cows were formed: the first (I) group – descendants of bulls of Canadian origin, the second (II) group – German, the third (III) group – Dutch, and the fourth (IV) group – American (USA) origin. Statistical data processing included a Student’s t-test for independent and paired samples, Pearson’s correlation coefficient, and a one-way ANOVA. A statistically significant effect of the CO of breeding bulls on the milk productivity of primiparous cows was established. The highest level of productivity in quantitative terms was demonstrated by the daughters of Dutch bulls, which significantly exceeded the indicators of the progeny of other groups: in milk yield by 320.0–419.3 kg (P < 0.001), in amount of milk fat by 12.1–16.4 kg (P < 0.001), and in amount of milk protein by 10.0–12.9 kg (P < 0.001). The results obtained partially contradict the data indicating the highest breeding value and transmission ability in American and Canadian bulls, but are consistent with the opinion of other scientists about the significant effect of the environment on the realization of the genetic potential of sires of different CO. During higher lactation, cows of all experimental groups had almost the same level of the milk productivity, which was confirmed by ANOVA. Daughters of Dutch bulls reached peak productivity at the earliest age (1.38), as evidenced by the smallest relative difference between lactations (d = 6.7–6.8 %; P < 0.001) and the highest repeatability (RC = 0.664–0.666; P < 0.001) of productive traits. This may indicate a potentially lower level of their productive longevity. Despite statistical significance (for the first lactation), the effect size of CO on the offspring is not large enough (η2 = 1.16–1.27 %; P < 0.001) to be a key criterion in the selection of a breeding bull. The revealed advantage of the daughters of Dutch sires, in particular NL 520813625 N.Ubrox and NL 447860719 Shirley, allows us to recommend them for widespread use in this herd. Conducting similar studies in other regions using linear mixed models will allow a more accurate assessment of the effect of the bull’s CO on the milk productivity of daughter cows, eliminating the effect of a number of genetic and exogenous factors. This will make it possible to develop more accurate and effective recommendations for domestic breeders, which can be implemented in various farms in Ukraine.
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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 | 0.001 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.003 | 0.000 |
| Bibliometrics | 0.000 | 0.003 |
| Science and technology studies | 0.000 | 0.008 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 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".