Which of the following is practised to overcome for average productivity in animals w.r.t. milk production, growth rate in beef cattle etc?

Options

A. Out-crossing
B. Cross-breeding
C. Interspecific hybridisation
D. Inbreeding

Answer

To address the question regarding the practices used to enhance average productivity in animals, particularly concerning milk production and growth rates in beef cattle, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding the Problem**: The question asks about practices to improve average productivity in animals, specifically in relation to milk production and growth rates in beef cattle.

2. **Identifying Relevant Practices**: The two main breeding practices that can be considered are:
- Outcrossing (Outbreeding)
- Crossbreeding

3. **Defining Outcrossing**: Outcrossing involves breeding animals from different breeds within the same species that are not closely related (i.e., they have no common ancestors for four to six generations). This practice helps to introduce new genetic material, which can improve traits such as milk production and growth rates.

4. **Defining Crossbreeding**: Crossbreeding refers to mating animals from different species, which can lead to the creation of new species. This is not the goal when trying to enhance productivity in existing livestock.

5. **Conclusion**: Based on the definitions and the goal of improving productivity without creating new species, outcrossing is the appropriate practice. Therefore, the correct answer to the question is **Outcrossing**.

### Final Answer:
The practice used to overcome average productivity in animals with respect to milk production and growth rate in beef cattle is **Outcrossing**.

---