Table 4. The seasonal average pig production efficiency from farm 3 and farm 4 between 2021–2022

Farm 3	Spring	Summer	Fall	Winter
Number of sows	964	856	911	933
Farrowing rate (%)	91.67±0.91	81.53±16.79	86.27±2.35	92.47±1.12
Farrowing interval (day)	151.23±2.22^ab	149.67±2.57^a	148.6±1.30^a	154.37±1.79^b
Litter size (total)	15.93±0.64	14.37±1.27	15.4±0.61	15.07±0.51
Litter size (alive)	14.2±0.46	13.13±1.01	13.73±0.32	13.8±0.61
Number of weaning piglets	12.07±0.21^a	9.47±3.33^b	11.77±0.49^a	11.83±0.042^a
LSY¹⁾	2.22±0.15^b	2.34±0.22^b	2.39±0.05^b	2.42±0.03^a
PSY²⁾	26.7±1.49^a	21.97±7.39^b	28.03±1.30^a	28.57±0.76^a

Farm 4	Spring	Summer	Fall	Winter
Number of sows	160	159	159	161
Farrowing rate (%)	86.1±2.91	86.83±6.14	79.67±14.28	85.83±9.59
Farrowing interval (day)	152.93±1.16	150.77±3.21	155.27±6.27	152.83±7.32
Litter number (total)	12.63±1.42	12.77±0.50	12.7±1.68	13.23±0.51
Litter number (alive)	12.1±1.21	12.47±0.40	11.7±1.97	12.4±0.70
Number of weaning piglets	10.27±0.87^a	9.17±0.45^b	10.63±0.64^a	10.73±0.35^a
LSY	2.28±0.04^a	2.21±0.01^b	2.3±0.12^a	2.34±0.06^a
PSY	23.47±1.95^a	20.17±1.00^b	24.57±2.78^a	25.17±1.16^a

Abbreviations: LSY, litter per sow per year;
PSY, piglets per sow per year.