There have been numerous false claims that yaks eat as little forage as 1% of their body weight per day as compare to beef cattle which consume up to 3%of their body weight in dry matter. Recent studies being conducted under a USDA Sustainable Agriculture Research and education Grant by the University of Kentucky show yaks consuming roughly 2.5-3% of their body weight in forage on a daily basis. A Yaks feed requirement will change depending on their production stage (ie third trimester pregnant cow, lactating cow, breeding mature bull, weaning calf, etc.).
Myth Busting: Nutrition of the Yak
Body Condition Scoring; are your animals at a healthy weight?
Lehmkuhler, Jeff, Les Anderson, Mary McCarty and Daniele Garner. 2023. A guide to body condition scoring yaks. ASC-255.https://publications.ca.uky.edu/files/ASC255.pdf
Why body condition score animals?
“Body condition scores reflect the plane of nutrition animals have been receiving in relation to their nutritional requirements. As animals consume more nutrients than needed, muscling and fat stores will increase leading to a higher BCS. If nutrient intake is less than the animal’s requirement to support lactation, growth, grazing activity, or energy to maintain core body temperature during cold weather, body stores are mobilized and BCS will decline.”
Minerals
Mineral program – excerpt taken from Introduction to Mineral Nutrition of Yaks Written by Dr. Jeff Lehmkuhler, University of Kentucky
Below is a brief summary of the available research on mineral needs of yaks.
- Sodium (Na): Herbage on the Qinghai-Tibetan Plateau is consistently deficient in sodium, leading to widespread sodium deficiency in yaks. The recommended dietary sodium requirement for yaks is 8-12 g/kg of the diet by Asian research. However, the level suggested for beef cattle in the NASEM Nutrient Requirements of Beef Cattle Publication is 6-10 g/kg.
- Phosphorus (P): Phosphorus is essential for various bodily functions, and its availability in forage for yaks is significantly affected by seasonality. During the summer, herbage in the northwest region of China has sufficient phosphorus. However, during the winter, it becomes deficient, leading to seasonal phosphorus deficiency in yaks. Seasonal forage phosphorus levels, forage type, and soil levels can influence plant phosphorus concentrations.
- Copper (Cu): Copper is crucial for various physiological processes, and like phosphorus, its availability in yak forage fluctuates with the season. Herbage copper content is generally sufficient in summer but deficient in winter. Additionally, high levels of molybdenum (Mo) in the soil and forage of some regions can induce copper deficiency, leading to a condition known as “shakeback disease”. Copper supplementation is necessary to prevent the disorder and deficiency in general, especially when molybdenum levels in feed/water are elevated
- Calcium (Ca): Calcium is essential for bone health, milk synthesis and other physiological processes in yaks. While herbage calcium levels may be sufficient for maintenance in some areas, yaks can still experience calcium deficiency, particularly during the spring when cows are lactating, and forage levels are low. This might be related to lower levels of vitamin D status during winter, as vitamin D is essential for calcium absorption and utilization. Reduced day length, excessive periods of cloud cover and heavy winter haircoats may reduce vitamin D synthesis.
- Selenium (Se): Selenium is an essential trace mineral, and deficiency is common in yaks grazing on the Qinghai-Tibetan Plateau, occurring in both summer and winter. Selenium status can vary from deficient to excessive in the United States so learning about the need for supplementation is important.
- Other Minerals: Other minerals, including potassium (K), magnesium (Mg), iron (Fe), manganese (Mn), and zinc (Zn), exhibit seasonal variations in their serum concentrations in yaks, typically with higher levels in the summer than in the winter. However, specific dietary requirements for these minerals in yaks have not been extensively studied.