By all means, if your hay source is not providing a reliable analysis, sample it yourself and get it done. If you don't know what's in there, you don't know what your cattle will need...
We got the vast majority of our hay in over the past week... but didn't receive the analysis from the hay producer until the day the last two loads arrived... UofArk testing lab showed good ADF(28) and TDN(58)... but crude protein was only 5%. University nutritionist doubts that TDN is as good as calculated, based on that low CP.
Below 7% CP, there is not enough N in hay for rumen microbes to effectively process that hay... they'll essentially starve to death with a belly full of indigestible material unless you're supplementing protein sufficiently.
This stuff we ended up with will require that we feed 2X-3X our normal level of DDG just to barely meet dry matter, protein, and net energy requirements.