(1) Number of adult sows
Heads of adult sows = number of commercial pigs slaughtered per year ÷ number of commercial pigs provided by each sow per year, according to the number of commercial pigs provided by each sow per year 18（MSY=18), then the number of adult sows = 10,000 ÷ 18 = 556 (head).
(2) Number of backup sows:
Annual renewal rate of sows is 33%, number of backup sows = number of adult sows x annual renewal rate, then number of backup sows = 556 x 33% = 184 (head).
(3) Number of boars:
male-female ratio is 1:25 (natural mating, artificial insemination male-female ratio is 1:100), number of boars = number of adult sows x male-female ratio, then the number of boars = 556x1÷25 = 23 (head). (Boars are usually kept in a single pen).
(4) Number of backup boars :
The annual renewal rate of boars is 33%, the number of backup boars = number of boars x annual renewal rate, then the number of boars = 23x33% = 8 (head).
(5) Pens for sows to be mated：
gestating sows and lactating sows The time of each type of pig group in the pen is generally as follows.
① breeding house = to be mated (7 days) + gestation identification (21 days) + sterilization (3 days) = 31 days;
② gestation house = gestation (114 days) - pregnancy identification (21 days) - advance into the maternity ward (7 days) + sterilization (3 days) = 89 days;
③ birth house = gestation (114 days) - pregnancy identification (21 days) - advance into the maternity ward (7 days) + sterilization (3 days) = 89 days;
④ Total time in pen = breeding house (31 days) + gestation house (89 days) + farrowing house (45 days) = 165 days;
⑤ The occupancy ratio of sows' rearing time in each pen was: 18.8% in the breeding house, 53.9% in the gestation house and 27.3% in the farrowing house.
(6) According to the above occupancy ratio, take 556 sows as an example, measure the various sow housing: breeding house with sows: 556x18.8%=104 (head); gestation house with sows: 556x53.9%=300 (head); farrowing house with sows: 60x27.3%=152 (head).
(7) On the basis of calculating the number of sows in each category, the number of spaces should be reserved appropriately, i.e., 110 spaces should be designed for breeding house, 315 spaces for gestation house and 160 spaces for farrowing beds in farrowing house.
(8) Nursery pen The nursery period of piglets is 35 days, which can be the same as the number of pens in farrowing house.
(9) Fattening house pen The fattening period is 90 days plus disinfection for 3 days for a total of 93 days, and its rearing period is 2~3 times of the nursery period, so its pen should be 2~3 times of the nursery period.
