צריכי דאי מהתם הוה אמינא להדיוט אבל לגבוה אימא לא נפסדינהו לכולהו
The Gemara explains that both the mishna here and the mishna in Avoda Zara are necessary, as, if this halakha had been learned only from there, the mishna in Avoda Zara, I would say that this applies only if the prohibited animal is intermingled with a non-sacred animal and thereby becomes prohibited to an ordinary person. But if it is intermingled with offerings that are designated to the Most High so a loss to the Temple would ensue, one might say that we should not lose all the valid offerings, and therefore the prohibited animal should be nullified in a simple majority. Accordingly, the ruling of the mishna here was necessary, to teach that the same applies to a mixture involving offerings.
ואי מהכא הוה אמינא הני מילי קדשים דמאיס אבל חולין דלא מאיס אימא איסורי הנאה ליבטלי ברובא צריכא
The Gemara continues: And conversely, if this halakha were learned only from here I would say that this statement, that the entire mixture is prohibited, applies specifically to sacrificial animals, as it is repulsive to sacrifice to God an animal from a mixture that includes a prohibited animal. But with regard to deriving benefit from a non-sacred animal from this mixture, which is not a repulsive act, one might say: Let the items from which deriving benefit is prohibited be nullified in a majority. Therefore, the mishna in Avoda Zara is also necessary.
וניבטלו ברובא וכי תימא חשיבי ולא בטלי הניחא למאן דאמר כל שדרכו לימנות שנינו
The Gemara questions the ruling of the mishna: But let the prohibited animals be nullified in a majority, as is the halakha concerning other matters, in which the minority items assume the status of the majority. And if you would say in response that animals are significant, as they are counted individually and therefore they are not nullified in a majority, this answer is unsatisfactory. The Gemara elaborates: This suggested answer works out well according to the one who says that we learned in the mishna discussing nullification in a majority (see Orla 3:6–7): Any item whose manner is also to be counted, i.e., that are sometimes sold by unit rather than weight or volume, is considered significant. This definition includes animals, as they are sometimes sold as individual animals, and therefore they would be considered significant.
אלא למאן דאמר את שדרכו לימנות שנינו מאי איכא למימר דתנן מי שהיו לו חבילי תילתן של כלאי הכרם
But according to the one who says that we learned in that mishna: An item whose manner is exclusively to be counted, i.e., one that is always sold by unit, is considered significant, what can be said? Although animals are often sold by unit, they are occasionally sold as part of a herd, and would therefore not be considered significant. The Gemara cites the mishna in which this dispute appears. As we learned (Orla 3:6–7): With regard to one who had bundles of fenugreek, a type of legume, that were diverse kinds planted in a vineyard, from which it is prohibited to derive benefit,