Sows usually have 114 days of pregnancy
The average time from weaning to re-breeding was 14 days.
Modern factory pigs are mostly weaned at 18-21 days
Breeding period = sow pregnancy + piglet lactation + sow weaning to re-stocking time = 114+20+14=148 days
The number of litters per year (parities) = 365 / reproductive cycle = 365/148 = 2.47 tires
The source of 2.47 (theoretical basis)
The number of litters per year (parities) = 365 / reproductive cycle = 365/148 = 2.47 tires
Decomposition of 148 days (=114+20+14+?):
114: Pregnancy. Can not be reduced.
20: Weaning age. Can be reduced. However, for the re-breeding of weaned sows, the reduction does not make sense either.
14: Assuming 30 weanings at a time, the weaning estrus rate is 80%, and 2 are not estrus. After 42 days of weaning, the remaining (30-30*80%-2=) 4 heads are estrus on the 40th day. The time from weaning to estrus is considered. It is (6*24+40*4+42*2)/30=12.93 days.
?: A value related to the birth rate. For 148 days, the value is ignored. What should be the value? How can this value be derived?
148 days is a theoretical value.
148 In addition to the impact of 14, is also subject to? Impact.
What this means: In the above formula, we assume that all newly-fed sows are pregnant. However, the actual situation is not the case. This has the concept of birth rate.
Childbirth rate = number of heads of delivery / number of heads of first breeding *100%
With regard to the number of initial mating heads, although the breeding stock was originally bred, the small number of sows who returned to the middle of the road, miscarriage, and death must increase 148 in the process of re-breeding (or supplementing the reserve). It means that the value added on the basis of 148
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