Seamus Heaney is an Irishman who grew up on a farm and became a poet who often wrote about the things he knew best. "Cow in Calf" is an example of his experience with the intimate workings of farm life. This poem is, in its simplest form, his reflection about one of the most basic farm and life realities, birth and renewal.
Our first indication of this theme comes from the title. The poem describes a very pregnant cow, and if it were to reflect reality, the title should properly be "Calf in Cow." Right? The calf is in the cow. Instead, we have the reverse, implying that what is needed to be an adult cow is already part of the unborn calf's identity. Consider the kind of cycle of life indicated in the following images from the poem: "cud," "milk," "heat" and "calves." This is the process of growing from a calf into a cow producing more calves, thus the theme of birth and renewal.
In form this poem is a sonnet, though it does not follow the traditional rhyming pattern of either an Elizabethan or an Italian sonnet. A sonnet suggests something much loftier than a mother cow glutted with a calf, and yet what theme is more significant or universal than this theme. All living things experience this cycle, and by putting this poem in sonnet form Heaney elevates the mundane (a pregnant cow) to something more eternal and relevant.
The poetic elements of this poem are simple but eloquent. First of all you will recognize alliterative pairs (two words which share the same beginning consonant sound) throughout the poem, beginning with the title, "Cow in Calves." Though the alliterative words are not always contained in the same line, they are quite distinctive as you read. Note "barrel" and "belly," "haunches" and "hammock," "slapping" (twice) and "seed," and "hit" and "heard." In such a short poem containing such short lines, these are clear musical elements when it is read aloud. And, when you read just those alliterative words, they impactfully represent many of the key ideas of the poem.
The poem is replete with sensory imagery, beginning with a pregnant cow whose belly looks like she "swallowed a barrel." We also experience her growing udders that look like "Windbags / of bagpipes." Sound (aural) imagery includes the "slapping" of the speaker's hand against the cow's body, making the same dull sound as if he had slapped "a great bag of seed," and of course the discussion of "lowing" and cud-chewing. The two most significant sound images are the bagpipes and the underwater bomb that explodes. Both are rather vivid and haunting images suggesting the end of life, rather than the beginning. Smell and touch are evident everywhere, as well.
Again, in one way this is a simple description of a man trying to rouse a very pregnant cow from her resting place in the "byre." The comparisons (mostly similes) are fairly simple early on (a barrel, a hammock, and a bag of seed), but they grow more complex (a bagpipe and "a depth charge / underwater bomb") as the poem progresses. The image of the hammock is comfortable and knowable; but the other two are more disconcerting. The "drone" of the bagpipes is the low, carrying note, like a cow's lowing or a funeral song. The speaker says
...I had to hit her again and again
and heard the blows plump like a depth charge
far in her gut.
This dull thud evokes war and death, also inevitibilities in life. Perhaps these are the subtle reminders that death is also part of the birth and renewal process.