Yes, there were cows in 7th century Arabia during Muhammad's time.

The second surah (chapter) of the Quran, Surah Baqarah, is translated as "The Cow".

There are also many references to Cows in Hadith (Records and Sayings of the Prophet), for example:

Hadith

حَدَّثَنَا عُثْمَانُ بْنُ أَبِي شَيْبَةَ، حَدَّثَنَا وَكِيعٌ، عَنْ شُعْبَةَ، عَنْ مُحَارِبِ بْنِ دِثَارٍ، عَنْ جَابِرٍ، قَالَ لَمَّا قَدِمَ النَّبِيُّ صلى الله عليه وسلم الْمَدِينَةَ نَحَرَ جَزُورًا أَوْ بَقَرَةً ‏.‏

Narrated Jabir ibn Abdullah:

When the Prophet (ﷺ) returned to Medina, he would slaughter a camel or a cow.

Sahih in chain (Al-Albani)

Sunan Abi Dawud 3747 In-book : Book 28, Hadith 12 English translation : Book 27, Hadith 3738 Abu Dawood