CNV detection tools like cnv-facet and cnvpytor (which is a python wrapper of CNVnator) have been successfully deployed on many different non-model species. I've used CNVnator on a diploid fish species without any problems. Whilst assumptions about data quality might differ in non-model species, you should be fine with cow which has chromosome level assemblies.
If you're not getting any results I suspect there is an issue with the quality of your data, a mistake in the data processing, or you haven't followed the instructions correctly. Impossible to say without any detail.
Some things that may be useful to know:
- What is your input data? (Platform, depth, etc...)
- How have you processed/cleaned the data?
- What reference genome are you using?
- What does the run log say?
- If everything looks good until here, then maybe we should look at the commands you used.