The First 8 Lunar Days

According to an ancient record in the Jin Dynasty, the 1st few lunar days are named according to the animals and followed by food.

The 1st Lunar day is the day of the Chicken.

The 2nd Lunar day is the day of the Dog.

The 3rd Lunar day is the day of the Pig.

The 4th Lunar day is the day of the Sheep.

The 5th Lunar day is the day of the Ox.

The 6th Lunar day is the day of the Horse.

The 7th Lunar day is the day of Human.

The 8th Lunar day is the day of the grains.

This is the Chinese saying: "一日为鸡日，二日为犬，三日为猪，四日为羊，五日为牛，六日为马，七日为人，八日为谷。"

Hence, the ancient Chinese set the first Lunar day as the birthday of the Chicken, the second day as the birthday of Dog and so on. And this is how the Human is created or born on the 7th day which is known as 人日.

The practice further continue -  to stop slaughtering or eating chicken on the 1st lunar day, and not eating Dogs on the 2nd day and so on.