This paper is about the Genetic variants in the serum amyloid A2 (SAA2) gene as a potential marker for milk production traits in Chinese Holstein cows. Overall the research design is good and results are convincing. However, there are some shortcomings in this manuscript that needs revision.
Line 19: Please rewrite this sentence.
Line 26: What does the word contention mean? Please rewrite.
Line 28: Write the keywords in alphabetical order.
LINE 48: mention the reference.
Line 48: Introduction is weak. Please mention a number of previously done researches.
Line 48 -29 second paragraph remove been from this sentence first sentence five-line
please rewrite the goals of the study.
How to determine the genotypes is added.
What is the criterion for selecting fixed effects?
The variance justified by the gene is calculated.
What is the reason for the contradiction in deviating from the HWE?
The results of the association single markers are not listed in the table!
why the haplotypes are better? Please add the reason.
Table 4: P-value in the second column is wrong! p-value is 0.356 ! How is it significant?!
Please include line numbers and double-check author guide for formatting please check the writing style and format in our author guide and re-format/rewrite
The manuscript can still be improved revise by a native English speaker.

I appreciate your efforts to respond to my review comments.