(a) Describe the behavioural adjustments of animals during hot weather. (20 marks) (b) Describe the different bases of selection…

(a) Behavioural Adjustments to Hot Weather

Animals maintain homeostasis within a thermoneutral zone; in Indian tropical conditions, this zone is often exceeded, triggering behavioural adjustments distinct from physiological ones. Behavioural changes are voluntary and immediate, whereas physiological adjustments are involuntary metabolic responses.

The primary behavioural response is shade-seeking. Cattle and buffaloes move to shaded areas or water bodies to reduce solar radiation load. In poultry, birds spread their wings to increase surface area for convective heat loss and pant with open beaks to enhance evaporative cooling.

Activity levels drop significantly. Animals reduce voluntary movement to minimize metabolic heat production. Feeding patterns alter, with peak intake shifting to cooler hours (early morning or late evening) to avoid the heat of the day. Postures change: animals stand more, stretch out and spread their limbs, and keep greater spacing from herd mates to cut heat exchange, while crowding around water troughs and drinking more.

Species-specific variations are notable. Buffaloes, being less heat-tolerant than cattle (dark skin and sparse sweat glands), often wallow in water or mud, using evaporative cooling from their skin. Cattle, having functional sweat glands, rely on sweating, panting and shade. Sheep and goats seek shade, cut midday grazing and increase water intake. These behavioural shifts are critical for survival but can impact productivity if prolonged, leading to heat stress.

(b) Bases of Animal Selection

Selection is the cornerstone of genetic improvement. It is broadly classified into natural and artificial selection. Natural selection operates through environmental pressures, while artificial selection is human-directed to enhance desirable traits.

Within artificial selection, several methods are employed:

1. Mass Selection: Selecting individuals based on their own phenotype without pedigree information. This is common in small ruminants and pigs where records are sparse.
2. Pedigree/Lineage Selection: Using the performance of ancestors to predict an animal’s merit. This is useful when individual records are unavailable.
3. Family Selection: Selecting whole families based on the average performance of the family (full- or half-sibs).
4. Progeny Testing: Evaluating a sire’s genetic merit by testing the performance of its offspring. This is the gold standard for dairy sires. For example, in the Murrah buffalo progeny testing scheme, bulls are evaluated based on the milk yield of their daughters. Because milk yield is a sex-limited trait, a bull's breeding value for it can only be judged through his daughters.
5. Genomic and Marker-Assisted Selection (MAS): Modern approaches using DNA markers to predict genetic merit early in life, accelerating the rate of genetic gain.

Selection criteria include production traits (milk yield, growth rate), functional traits (fertility, longevity), and health traits (disease resistance). Economic weights are assigned to these traits to maximize net profit.

(c) Methods to Educate Farmers

Extension services translate research into practice. Methods are categorized into individual, group, and mass media approaches.

Individual Contact Methods involve direct interaction, such as farm and home visits, office calls and result demonstrations on the farmer's own field. These are effective for addressing specific farm problems but are time-consuming.

Group Methods leverage peer learning. Farmer Field Schools (FFS) are participatory training programs where farmers learn by doing. Group discussions and training camps facilitate the exchange of experiences among farmers.

Mass Media reaches a large audience simultaneously. Doordarshan's DD Kisan channel and All India Radio farm broadcasts disseminate information, while Krishi Vigyan Kendras (KVKs) add exhibitions and kisan melas. Kisan Call Centres provide voice-based advisory services.

Participatory and ICT-Based Approaches are increasingly vital. Farmer Participatory Research (FPR) involves farmers in the research process, ensuring relevance. Participatory Rural Appraisal (PRA) tools help map local resources and constraints. ICT innovations like mKisan (SMS-based alerts) and WhatsApp groups are effective, but it must be noted that SMS requires literacy or a reader. To bypass literacy barriers, Interactive Voice Response (IVR) systems and voice messages are more suitable for low-literacy rural contexts.