Bhashya
तस्मिन् आदित्ये अवयवविभागश इमानि वक्ष्यमाणा-नि सर्वाणि भूतानि अन्वायत्तानि अनुगतान्यादित्यमुपजी-व्यत्वेन इति विद्यात् ।कथम् ? तस्य आदित्यस्य यत्पुरोदयात् धर्मरूपम्, स हिंकार भक्ति , तत्रेद् सामान्यम्, यत्तस्यहिंकारभक्तिरूपम् ।तदस्यादित्यस्य साम्न पशव गवादयअन्वायत्ता अनुगता तद्भक्तिरूपमुपजीवन्तीत्यर्थः ।यस्मा-देवम्, तस्मात्ते हिं कुर्वन्ति पशव प्रागुदयात् ।तस्माद्धिंका-रभाजिनो हि एतस्य आदित्याख्यस्य साम्न , तद्भक्तिभजन-शीलत्वाद्धि त एव वर्तन्ते ॥
In plain words
Understand that all these beings are dependent upon the sun, sustained by it part by part. How? The pre-dawn attribute of the sun corresponds to the him-kāra part of the chant. This is the common link: the animals, such as cows, depend on that very phase of the solar sāman for their sustenance. Because of this, animals utter their sounds before sunrise. They truly share in the him-kāra of this solar sāman, for their natural habits reflect that very division.
Close to the Sanskrit
In that sun, part by part, one should know all these beings to be dependent, as being sustained by the sun. How? That which is the pre-dawn form of that sun, that is the him-kāra division. Here is the common feature, which is its form as the him-kāra division. That means: cows and other animals, dependent and following that sun, sustain themselves upon that division of its sāman. Since it is thus, therefore those animals make the him sound prior to sunrise. Therefore they are partakers of the him-kāra of this sāman named after the sun, indeed because they are of the nature of engaging in that division.