# Changes and Correlation Between Hormones, Immunoglobulins, and Minerals in Blood Serum and Hair of Tianzhu White Yaks of Different Ages and Gender

## TL;DR

This study examines how hormones, immune proteins, and minerals in blood and hair change with age and gender in Tianzhu white yaks, showing that younger yaks have higher levels of certain hormones and immune proteins linked to hair growth.

## Contribution

The study identifies age- and gender-specific correlations between hormones, immunoglobulins, and minerals in yaks, offering a non-invasive method to assess their health.

## Key findings

- Younger yaks (1–2 years) have significantly higher melatonin and dihydrotestosterone levels, which are important for hair growth.
- IgA levels are higher in younger yaks, while IgG and IgM decline with age.
- Calcium, magnesium, zinc, and iron levels in blood serum are higher in younger and older yaks compared to 3–4-year-olds.

## Abstract

This study was designed to probe into the changes in the hormones, immune system proteins, and minerals in the blood and hair of Tianzhu white yaks across different age groups (ranging from 1–2, 3–4, and 5–6 years old) and genders. The results showed that compared with older yaks, younger ones had remarkably higher levels of melatonin and dihydrotestosterone, both of which are crucial for hair growth. Additionally, it was confirmed that the younger yaks contained a greater amount of immune protein IgA, while the levels of IgG and IgM gradually declined as they grew older. In terms of certain minerals in the blood serum, like calcium, magnesium, zinc, and iron, their concentrations were considerably higher in younger and older yaks than in the 3–4-year-old group. In contrast, significant differences in hair minerals were observed among all age ranges, with different change trends for each mineral. Since hair growth is affected by these elements, monitoring them can effectively evaluate the health and nutritional status of yaks. This non-invasive method can assist farmers in closely observing the yaks’ health and making timely adjustments to feeding or treatment plans.

(1) Background: Hair growth can function as an indicator of an animal’s health and nutritional status, furnishing a valuable means for early diagnosis and timely modifications to management practices, and is influenced by hormones, the immune system, and the levels of minerals within the animal’s body. (2) Methods: In this study, a total of 81 yaks were selected and divided into three groups according to their ages (1–2 years, 3–4 years, 5–6 years), and the concentrations of melatonin, dihydrotestosterone, IgA, IgG, and IgM in their blood serum and the levels of Ca, Mg, Zn, Fe, and P in both their blood serum and hair were detected. (3) Results: The levels of melatonin and dihydrotestosterone in yaks aged 1–2 years were significantly higher than those of other age groups (p < 0.001). In addition, the concentration of melatonin in male yaks was markedly greater than that in female yaks (p < 0.05). When it came to immunoglobulins, the IgA level in 1–2-year-old yaks was strikingly higher than those in yaks aged 3–4 years and 5–6 years (p < 0.05). In terms of mineral elements, the concentrations of calcium, magnesium, zinc, and iron in the blood serum of 1–2-year-old and 5–6-year-old yaks were significantly elevated compared to those in 3–4-year-old yaks. However, there was no notable difference between the 1–2-year-old and 5–6-year-old groups. The correlation analysis showed that there was a significant correlation between DHT and the levels of melatonin and IgA in yaks. Additionally, a significant correlation was observed between IgA and IgG, as well as between IgA and the levels of Fe, Mg, and Ca. It is likely that they jointly regulate the hair growth and immune processes of yaks. (4) Conclusions: There are positive correlations among melatonin, dihydrotestosterone, and IgA in the blood serum and the content of Fe and Mg in the hair to varying degrees, implying these indicators may jointly regulate yak hair growth and immune status. These research findings provide data support for applied research into evaluating the overall health status of yaks through the growth status of hair or by measuring the mineral content in hair in a non-invasive way.