Gemara

Rav Huna and Rav Chisda (to Geneiva): Please taste something!

Geneiva: Rav Yehudah forbids tasting anything before feeding his animal;

It says "I will give grass in your field for your animals", and afterwards "you will eat and be satiated."

Berachos 40a (Rav): If one blessed ha'Motzi and (before he ate) said "take a piece", he need not bless again. If he said "bring salt or relish," he blesses again.

(R. Yochanan): If he said "bring salt or relish", he does not bless again. If he said "knead the bran (with water) for the cattle," he blesses again;

(Rav Sheshes): Even in this case he does not bless again;

(Rav Yehudah): One may not eat before feeding his animal.

Rishonim

The Rif and Rosh (Berachos 28a and 6:23) bring the Gemara in Berachos. Their text forbids to 'taste anything' before giving to one's animal, like the text in Gitin.

Rosh: Since one may not eat before feeding his animal, saying "knead the bran for the cattle" is a need of the meal, and it is not an interruption.

Rambam (Hilchos Avadim 9:8): Previous Chachamim used to put food of the animals and slaves before their own food.

Even ha'Ezel: Perhaps the Rambam learns from Kesuvos 61a that it is only Midas Chasidus to give to one's slaves before himself, and all the more so to one's animals. However, perhaps there the slaves already ate, and it is Midas Chasidus to let them taste each dish before he himself does.

Note: I do not understand the Kal va'Chomer. The Rambam rules that one need not feed his slave at all!

Rambam (Hilchos Berachos 1:8): If one interrupted between a Berachah and eating he must bless again, unless the interruption pertained to what he blessed on, e.g. to feed an animal.

Kesef Mishneh: The Rambam rules like Rav Sheshes, who is Basra (later).

Question (Tzlach Berachos 40a DH v'Rav Sheshes): We follow Basra only after from Abaye and Rava! Why should we follow Rav Sheshes against Rav and R. Yochanan? Perhaps Rav agrees with Rav Sheshes, and R. Yochanan is a minority against them. See Noda bi'Yehudah (1 YD 26. The Rosh rules like R. Yochanan even against Rav and Shmuel and other Amora'im.)

Poskim and Acharonim

Shulchan Aruch (OC 167:6): If one interrupted between a Berachah and eating he must bless again, unless the interruption pertained to what he blessed on, e.g. ... give food to the animal.

Beis Yosef (DH v'Yochal): Rashi connotes that even an interruption for the sake of eating requires a new Berachah if it is not needed for the slice of ha'Motzi. 'Knead for the animal' is not an interruption, for one may not taste before eating. The Rambam connotes that anything for the sake of eating is not an interruption. We are lenient about Safek Berachos.

Rebuttal (Taz 7): Rashi must agree that needs of the meal not needed for the slice of ha'Motzi are not interruptions! We learned that one may not taste before praying (Shabbos 9b) or saying Havdalah (Pesachim 105a). Here, it forbids eating before giving to his animal. Also, if tasting were forbidden, the Gemara would have said only 'and afterwards, "you will eat."' It continued "and be satiated" to teach that only such eating is forbidden.

Shevus Yakov (3:13): It seems from Gitin 62a that one may not taste at all before giving to his animals! Perhaps the Taz follows the Gemara in Berachos because the Halachah was taught there. (In Gitin, it was merely mentioned in passing.) Or, it is Derech Eretz to offer one to taste, even if one intends for a fixed meal. Geneiva adapted the text of Rav Yehudah's teaching to correspond to the offer. However, the Taz does not allude to either of these answers. I say that we rely on the Rif, Rosh, Agudah and Shibolei ha'Leket, who forbid tasting. They knew the correct text better than we do. Or, they are stringent about the Safek. We do not distinguish between birds, Behemos, or Chayos, be they Tahor or Tamei. "You will eat and be satiated" is not a proof. The Isur is mid'Rabanan; the verse is only an Asmachta.

Nishmas Adam (on Chayei Adam 5:11): Perhaps the Beis Yosef's text also in Berachos said 'before tasting.' If so, l'Chatchilah one may interrupt to say 'feed the animals.' However, the Rambam holds that that it is only Midas Chasidus, not an Isur, to eat first. Perhaps he had a different text. I think that whether the text says 'eat' or 'taste', one may not taste only if one intends to eat a fixed meal.

Sefer Chasidim (531, cited by Magen Avraham (18): Regarding drinking, people come first - "you will give to ha'Edah (Yisrael) to drink, and to their animals" (Bamidbar 20:8). We find that Rivka gave to Eliezer to drink before giving to the camels, but they fed the camels before giving the men to eat.

Mishbetzos Zahav (7): What is the proof from Rivka? If one asks Ploni for a drink, surely Ploni will not say 'first I will give to your animals!" Perhaps the camels already drank water suitable for animals, and Eliezer wanted clear water that people drink! The proof is from Eliezer, who asked for himself, and not for the camels. He asked for a little water, and she answered that she will give to him to drink as much as he wants, and afterwards for the camels.

Machatzis ha'Shekel (18): Since the Torah recorded Rivka's words, surely the Halachah follows her. Perhaps giving to animals to drink is not a need of the meal, and it would be an interruption between a Berachah and eating.

Igros Moshe (OC 2:52 v'Hinei): If R. Eliezer were obligated to give to his animals before drinking, Rivka would have given according to his obligation!

Torah Temimah (Devarim 11:15): Sometimes people eat even though they are not hungry (Tosfos Pesachim 107b DH Dilma), but they drink only when they are thirsty. Man's pain comes first. Chachamim did not specify, but indeed, when one is hungry he may eat first. It is only Midas Chasidus not to.

Kaf ha'Chayim (50): Some say that animals come first also regarding drinking. If so, saying 'give the animals to drink' is not an interruption between a Berachah and eating or drinking.

Kaf ha'Chayim (51): If others give to a person, he need not give to his animals before eating or drinking it.

Kaf ha'Chayim (52): One may eat once he commanded to feed his animals (even if the food was not yet put in front of them).

Kaf ha'Chayim (53): One need not give to his dog or cat before he himself eats. One who is meticulous about his deeds should do so.

Kaf ha'Chayim (54): The Kesav Sofer says that perhaps one may eat first on Shabbos and Yom Tov, and if so saying 'give the animals to eat' is an interruption. Pischei Teshuvah says that it is not, for it is related to the meal.

Rema: L'Chatchilah, one should not interrupt at all.

Kaf ha'Chayim (56): Before washing, one should arrange to bring salt and give to people and animals to avoid a need to interrupt. If he already blessed, he should not interrupt to command to feed animals, for some say that it is only mid'Rabanan, and some say that it is only Midas Chasidus.

Magen Avraham (271:12): Some say that if one blessed on bread and remembered that he did not say Havdalah, the Berachah was l'Vatalah, and he must bless again after Havdalah. This is unlike 'knead for the animals', for the Torah forbids eating before one's animals.

Einayim l'Mishpat (Berachos 40a:[2], from DH v'Efshar): Perhaps the opinion that the Isur to eat before feeding his animal is mid'Oraisa forbids tasting beforehand, like the Terumas ha'Deshen says about Kri'as Shema, and the opinion that the Isur is mid'Rabanan forbids only a meal beforehand. Some permit tasting before feeding his animal. All the more so they permit drinking! Even those who forbid tasting beforehand forbid only mid'Rabanan. The Torah commands to feed animals only before "you will eat and be satiated." Chachamim did not decree about drinking, for it does not take long.

Ben Yehoyada (Berachos 40a): Since the end of animals is to be food for man, it is proper that we let animals eat first. We do not distinguish, and apply this even to Tamei animals that we do not eat. Regarding drinking, man is like the host, and animals are like guests. Normally, the host has precedence.