• Weaning Age in Swine Production:
• Traditional/Conventional Weaning: 8 weeks (56 days) of age.
• Standard Intensive Commercial Weaning: 3 weeks (21 days) of age, allowing sows to cycle within 5–7 days post-weaning and achieve a farrowing index of $\gt 2.2$.
• Segregated Early Weaning (SEW): Can be practiced at 10–14 days with medicated milk replacers, but under standard commercial farm management, 21 days represents the earliest practical weaning age.

Correct option: (3) 21 days

• Equine Reproduction Characteristics in Mares:
• Seasonally Polyestrous: Mares cycle repeatedly during long daylight hours (long-day seasonal breeders).
• Breeding Seasons: Under natural photoperiods, estrous cycles begin in spring and peak through summer/early autumn.
• Winking of the Vulva: Frequent rhythmic eversion of the clitoris and vulva ("winking") accompanied by squatting and tail raising is the pathognomonic behavioral sign of standing estrus.
• Peak Breeding Season: Natural fertility and ovulatory regularity peak in late spring to early autumn.

Correct option: (3) (A), (B), (C) and (D).

• Water Requirements for Lactating Dairy Cows:
• lactating dairy cow requires approximately $3\text{ to }4\text{ liters}$ of water for every $1\text{ kg}$ of milk produced over and above maintenance water requirements ($40\text{--}50\text{ liters/day}$).
• In terms of milk produced per liter of drinking water:

or conservatively, $1\text{ liter of water}$ supports the production of $0.5\text{ kg}$ milk under balanced thermoneutral conditions.

Correct option: (3) 0.5 kg milk