A breed of cow is mated with closely related breed for five generations. It was found that production of milk has reduced subsequently and the animals are not keeping good health. Which of the following methods of animals breeding can overcome this problem?

Options

A. Hybridisation
B. Controlled breeding
C. Out-crossing
D. Crossing breeding

Explanation

To address the problem of reduced milk production and poor health in cows that have been mated with closely related breeds for five generations, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Problem**: The cows have been mated closely for five generations, leading to reduced milk production and health issues. This indicates a case of inbreeding depression, which occurs when closely related individuals are bred, resulting in a decrease in fertility and productivity.

2. **Understand Inbreeding Depression**: Inbreeding depression is characterized by a reduction in biological fitness due to the accumulation of deleterious alleles. In this scenario, the continuous mating of closely related breeds has likely led to a decrease in genetic diversity, which can adversely affect the health and productivity of the animals.

3. **Explore Breeding Methods**: To overcome the issues caused by inbreeding depression, we need to consider different breeding methods:
- **Hybridization**: This involves mating genetically distinct populations to produce hybrids. While beneficial in some contexts, it does not directly address inbreeding depression.
- **Controlled Breeding**: This method involves selecting animals based on specific phenotypic traits. However, it does not necessarily solve the problem of reduced genetic diversity.
- **Outcrossing**: This method involves mating individuals from different breeds or genetic backgrounds. Outcrossing increases genetic diversity, which can help improve health and productivity by reducing the effects of inbreeding depression.

4. **Select the Best Method**: Given the situation, outcrossing is the most effective method to overcome the problems associated with inbreeding depression. By introducing genetic variation through outcrossing, the health and milk production of the cows can be improved.

5. **Conclusion**: The best approach to resolve the issues of reduced milk production and poor health in the cows is to implement outcrossing.

### Final Answer:
The method of animal breeding that can overcome the problem is **Outcrossing** (Option C).