This is a very simple type of poetic metre, iambic) dimeter. Each line consists of just two feet, and each foot consists of an unstressed syllable followed by a stressed syllable:
> my **name** is **Cow** ,
> and **wen** its **nite** ,
> or **wen** the **moon**
> is **shiy** ning **brite** ,
> and **all** the **men**
> haf **gon** to bed -
> i **stay** up **late**.
> i **lik** the **bred**.
Wikipedia's example#Dimeter) of iambic dimeter is Robert Frost's "Dust of Snow", although not every line is four syllables:
> The way a crow
> Shook down on me
> The dust of snow
> From a hemlock tree
>
> Has given my heart
> A change of mood
> And saved some part
> Of a day I had rued.
You can see that the rhythm of the four-syllable lines in this poem is the same as in the one that you're asking about.