CBSE Class 12 Biology Chapter 9: Strategies for Enhancement in Food Production NCERT Solutions

Solution: Animal husbandry is the scientific practice of managing domestic animals like cattle, pigs, sheep, poultry, and fish. Its primary role in human welfare is to increase the availability of essential food products and other resources. This involves careful attention to feeding, breeding, housing, and healthcare to enhance the population and productivity of livestock. By improving these aspects, animal husbandry ensures a steady supply of commercially important products such as milk, meat, eggs, wool, honey, and silk, which are vital for nutrition, economy, and livelihood, especially with the growing global human population.

Solution: To improve both the quality and quantity of milk production on a dairy farm, several key measures would be undertaken:

1. Breed Selection: Choose high-yielding breeds of cattle, preferably hybrids, that possess desirable genes for both high milk production and resistance to common diseases.
2. Proper Nutrition: Ensure the cattle receive a balanced and nutritious diet. This includes adequate roughage, fibre, concentrates, and sufficient levels of proteins, vitamins, and minerals essential for milk synthesis.
3. Adequate Shelter: Provide a clean, well-ventilated, and comfortable housing environment that protects the cattle from extreme weather conditions like excessive heat, cold, or rain.
4. Hygiene and Health Management: Maintain strict hygiene by regularly cleaning the cattle and their surroundings. Implement a schedule for regular check-ups by a veterinary doctor to detect and treat any diseases promptly, preventing potential losses and ensuring animal well-being.

Solution: A 'breed' refers to a specific group of animals within a species that share common and distinct characteristics, such as general appearance, size, body structure, and other features. For example, Jersey and Brown Swiss are distinct breeds of cattle known for their high milk production and nutritious milk.

The primary objectives of animal breeding are:

• To increase the overall yield of animals (e.g., more milk, meat, or eggs).
• To improve the desirable qualities of the animal produce (e.g., higher protein content in milk, better wool quality, or leaner meat).
• To develop and propagate varieties of animals that are resistant to diseases, thereby reducing losses and improving herd health.

Solution: The primary methods employed in animal breeding can be broadly classified into two main categories: inbreeding and outbreeding.

1. Inbreeding: This involves the mating of animals that are closely related, typically within the same breed, for several generations. It helps to increase homozygosity and fix desirable traits but can also lead to inbreeding depression if harmful recessive alleles accumulate.
2. Outbreeding: This involves mating animals that are not closely related. It includes several types:
   • Out-crossing: Mating between animals of the same breed that have no common ancestors up to 4-5 generations. This is done to avoid inbreeding depression and introduce vigour.
   • Cross-breeding: Mating between animals of different breeds of the same species. This method aims to combine the desirable qualities of both parent breeds to produce a superior hybrid offspring. For example, crossing a local breed with a foreign breed known for high milk yield.
   • Interspecific Hybridization: Mating between individuals of different species. This is a rarer method and often results in infertile offspring, but can be used to introduce specific traits.

Which method is best?

The 'best' method depends on the specific goals. However, cross-breeding is often considered highly effective for enhancing desirable traits. It allows for the combination of superior qualities from different breeds, leading to offspring with improved productivity, disease resistance, or other valuable characteristics that might not be found in a single breed. For instance, crossing a hardy local breed with a high-yielding exotic breed can result in a new breed that is both productive and adapted to local conditions.