Study on the influence of different production factors on PSY and its correlation

Table 1 Descriptions of productive performance between total pig farms and top 5% pig farms

	Mean	Median	Minimum	Maximum	SD
	Total pig farms (n = 603)/Top 5% pig farms (n = 29)
Total number of piglets per litter^a	11.3/12.1	11.4/12.2	9.0/10.0	14.9/14.9	1.0/0.9
Number of piglets born alive per litter^b	10.4/11.5	10.4/11.5	7.5/9.4	14.1/14.1	1.0/0.9
Number of weaned piglets per litter^c	9.4/10.5	9.4/10.4	6.8/9.0	12.4/12.4	1.0/0.6
Farrowing rate (%)^d	78.2/87.4	81.2/88.5	36.6/58.5	99.2/99.2	12.3/6.8
Stillbirth rate (%)^e	6.4/3.9	5.7/3.6	3.1/0.6	18.4/8.8	2.9/1.7
Mummified piglets rate (%)^f	2.0/1.4	1.7/1.3	0.6/0.0	9.9/5.2	1.2/0.9
Return-service rate (%)^g	14.4/6.0	12.9/5.0	2.7/1.2	46.9/13.0	8.3/3.5
Mating rate within 7 days after weaning (%)^h	55.7/69.2	58.2/69.9	0.0/19.2	85.8/83.8	16.5/12.6
Weaning to breeding intervalⁱ	17.2/9.6	12.8/9.0	4.7/6.5	23.5/22.0	13.8/3.1
Non-productive days^j	84.1/50.0	76.8/45.7	27.4/27.7	270.0/113.6	38.2/17.8
Production days^k	686.5/1481.0	502.0/763.0	120.0/280.0	5176.0/5176.0	768.6/1368.1
Birth weight of piglets (kg)^l	1.2/1.2	1.2/1.2	1.0/1.0	1.6/1.5	0.1/0.1
21-day adjusted weight of piglets (kg)^m	5.7/6.0	5.7/6.2	4.4/4.9	7.3/7.3	0.5/0.5
Longitude	113.8/111.4	113.5/109.0	104.8/103.2	128.8/123.4	5.6/7.1
Latitude	33.9/33.8	35.1/34.1	23.3/23.4	47.7/42.7	6.0/5.3

^aTotal number of piglets per litter: Total number of piglets per litter/Number of litters
^bNumber of piglets born alive per litter: Number of piglets born alive/Number of litters
^cNumber of weaned piglets per litter: Number of weaned piglets/Number of litters
^dFarrowing rate: Number of farrowed litters/(Number of farrowed litters+Gestation loss of 115 days pushed forward in the research stage)
^eStillbirth rate: Number of stillbirth/Total number of piglets
^fMummified piglets rate: Number of mummified piglets/Total number of piglets
^gReturn-service rate: Number of return service sows/Number of mating sows
^hMating rate within 7 days after weaning: Number of mating sows within 7 days after weaning/(Number of weaned sows7 days ago—number of culling sows 3 days ago—number of dead sows within 7 days after weaning)
ⁱWeaning to breeding interval: The first mating date of the sow in this breeding cycle—The weaning date of the sow in the same parity
^jNon-productive days: (Sum of non-productive days of all sows in the research stage/Days in the research stage) × 365.25/Average number of sows in the research stage
^kProduction days: Date of the last day of the research stage—Date of production started
^lBirth weight of piglets: Sum of birth litter weights in all birth records during the research stage/Number of born alive piglets
^m21-day adjusted weight of piglets: Actual average weaning weight×(2.218−0.0811×Average weaning age+0.0011×Average weaning age^2)

ISSN: 2055-5660