How is the age of the cow judged? Look at the angle of the teeth to identify the age of the cow!

How is the age of the cow accurately judged? Some people want to buy cows, but they don't know how to judge the age of cows. This is really a worrying thing. When purchasing cows, the accurate age identification can not only determine the utilization potential and age of the cows, but also judge the reproductive performance of the cows by the corresponding relationship between the age and the parity of the cows.

First, according to the age of teeth identification

1. The type and number of teeth and the teeth of the toothed cattle are divided into milk teeth and permanent teeth (constant teeth) according to the birth. The gingival teeth are small and white, with gaps between the teeth, flat surface, thin and detailed teeth, and obvious neck. When it reaches a certain age, it is replaced by permanent teeth. A total of 10 pairs of 20 teeth, no posterior molars, its tooth type: 2 × (end tooth 0 / 4, canine 0 / 0, front molar 3 / 3, posterior molar 0 / 0) = 20. The shape of the permanent incisors is relatively large and thick, the crowns are long and neatly arranged, there is no gap between the teeth, the roots are brownish yellow, and the leucorrhea of ​​the crown is yellowish, which is far less white and fine than the milk teeth, so it is easy to identify. There are a total of 16 pairs of 32 permanent teeth, the tooth type: 2 × (door tooth O / 4, canine 0 / 0, front molar 3 / 3, rear molar 3 / 3) = 32. There is no incisor on the upper part of the cow. When the age is identified, the 4 pairs of incisors are mainly seen. The middle pair of incisors is called the pincushion, the 1 symmetrical inner middle tooth on both sides, the 1 symmetrical outer middle tooth again, and the 1 symmetrical tooth on the outermost side. The molars have the front and back molars, each pair of 3 pairs, no special name, mostly named after the logarithm of the teeth.

2. The basis and method of identification are based on the age of the cattle to identify the cattle, mainly based on the regular changes of the occurrence, exchange and shape of the incisors. Generally, the yak has 1 to 2 pairs of deciduous teeth at the time of birth, and the gingival teeth of 3 to 4 months old are fully developed. The flank surface of the 4 to 5 months old wears gradually, and the gingival teeth begin to fall off and change the permanent teeth to a certain extent. The order of replacement is from the jaws and finally to the molars. When the incisors are replaced, they gradually wear out. Therefore, by the replacement and wear of the incisors, the age of the cows can be judged more accurately. The incisors of cattle from the middle to the sides, the exchange time difference is 1 year, so the shape of the outer pair of teeth changes one year later than the middle teeth, but the law is consistent.

The complete replacement of the incisors is called “Qikou”. The age of the cows is 5 years old. Before Qikou, the age identification method of cattle was summarized as: “one and a half years old, a pair of teeth; two and a half years old, two pairs of teeth; three and a half years old, three pairs of teeth; four and a half years old, four pairs of teeth.” At the age of 5, it began to change, showing a pair of permanent teeth. Generally, it takes half a year to grow up, that is, 2 years old and long. One pair of teeth on the outer side is replaced one year later. It can also be judged by the method of "log of permanent incisors +1 one age".

The age after the mouth is mainly judged by the tooth surface abrasion of the permanent incisors. The change rule of the shape of the tooth surface is: the initial shape is a rectangle or a horizontal ellipse. As the degree of abrasion is deepened, the rectangle gradually changes to a triangle, a quadrangle or an unequal and a circle. Each shape change takes 1 year, that is, the jaws are rectangular at 6 years old, triangles at 7 years old, quadrangular or unequal at 8 years old, and round at 9 years old. The remaining pairs of incisors exhibit the above regular changes one year later than the middle pair. After the age of 10, the dental caries cavity of the cattle is exposed, that is, the tooth star appears. The inner middle teeth, the outer middle teeth, and the molar teeth are tooth stars at the ages of 11, 12, and 13 respectively. Later, the circular longitudinal diameter of the tooth surface is enlarged, and the egg is rounded. The age is over 13 years old, collectively known as the old cow, no longer identified. In order to facilitate the memory, the age identification method of cows can be summarized as: “2, 3, 4, 5 look at the teeth. 6,7,8,9 look at the grinding surface, 10,11,12,13 to see the beads”.

At the time of identification, the appraisers stood near the left side of the head of the identified cow and caught the nose of the cow with bare hands or nose clamps. Hold the thinnest part of the nasal septum (the front edge of the nasal cartilage) with your left hand and lift your head so that it is level. Subsequently, the left hand corner of the cow was quickly inserted with the right hand, and the beef tongue was grasped through the toothless area, and the handle was twisted. Hold the upper jaw with your thumb, and hold the other four fingers in the tongue and pull it out to the left corner. Then check the changes of the incisors and measure the age of the cattle according to the criteria.

Second, according to the angular wheel identification

According to the production rules of dairy cows, under normal circumstances, there is only one parity per year, and a lactation peak appears, that is, there is only one obvious number of angular wheels. The initial time of the cow is usually 18 months old, so the first lactation peak is around 3 years old, and the first angle wheel appears at 3 years old. Therefore, the conversion relationship between the age of the cow and the angle wheel is: the age of the cow The number of rounds +2.

Because the reason for forming the angle wheel is more complicated, the angular wheel is often unclear, and the number is difficult to calculate. Therefore, the accuracy of determining the age is not high. However, according to the shape and number of the angle wheel, it can reflect the milking ability of the cow. For example, the angle wheel is clear, indicating that the milk yield is high; the angle wheel is fuzzy or the number of angle wheels is small, indicating that the cow has empty feeling or low milk yield. Explain that its productivity is low.

In normal times, under normal circumstances, the first child of 3 years old, the next year, the relationship between parity and age is: age = parity + 2, if the difference is too large, such as 6 years old cattle only 2, then The cow has been vacant and may have reproductive problems. Therefore, to choose a good cow, you must first judge the cow age!

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