1. Increased Milk Yield:
- BST is a growth hormone that stimulates milk production in cows.
- It increases the amount of milk produced per lactation cycle.
- Cows treated with BST may produce up to 10-20% more milk than untreated cows.
- The increase in milk yield is primarily due to an elevation of milk protein and fat content.
2. Altered Milk Composition:
- BST can affect the composition of milk produced by cows.
- It usually leads to an increase in the levels of protein and fat in the milk.
- The milk may also have a higher somatic cell count (SCC), indicating a potential increase in the number of white blood cells in the milk, which can impact milk quality.
3. Udder Health and Mastitis:
- BST can have an impact on udder health and the incidence of mastitis, an inflammation of the udder.
- Some studies have suggested that BST may lead to an increased risk of mastitis in cows due to the hormonal changes it induces.
- However, other studies have found no significant effect on mastitis occurrence or severity with BST usage.
4. Reproductive Performance:
- BST may affect the reproductive performance of cows, particularly in high-producing dairy herds.
- Studies have reported that BST treatment may delay the onset of estrus (heat) and reduce conception rates.
- These reproductive effects are likely related to the hormonal changes caused by BST.
5. Metabolic and Health Changes:
- Cows treated with BST may experience changes in their metabolism and overall health.
- They may have increased feed intake, altered glucose and insulin levels, and changes in body condition.
- In some cases, lameness and other health issues have been associated with BST usage, but the evidence on these effects remains mixed.
It's important to note that the effects of BST may vary among individual cows and herds. Management practices, nutrition, and overall herd health play a significant role in how cows respond to BST supplementation. Additionally, regulatory bodies in different countries have specific guidelines and approval processes for the use of BST in dairy cattle, considering the potential benefits and risks associated with its use.