Table 4.

Effects of sow parity on pig performance and carcass characteristics¹

	Quadratic coefficient			Linear coefficient
Item	Estimate	SE	P-value	Estimate	SE	P-value	Optimal parity2
Body weight, kg
Birth	−0.002	0.001	0.272	0.03	0.01	0.063	NA
Weaning	−0.009	0.004	0.012	0.09	0.04	0.014	4.8
Nursery exit	−0.046	0.021	0.026	0.62	0.20	<0.01	6.8
Finishing exit	−0.068	0.057	0.231	0.30	0.54	0.583	NA
Adjusted finishing (day 167)3	−0.362	0.080	<0.01	3.11	0.76	<0.01	4.3
Pig age, days
Weaning	0.000	0.012	0.975	−0.04	0.12	0.716	NA
Nursery exit	0.039	0.032	0.224	−0.14	0.31	0.659	NA
Finishing exit	0.321	0.077	<0.01	−3.05	0.72	<0.01	4.8
Slaughter	0.197	0.056	<0.01	−1.68	0.53	<0.01	4.3
Average daily gain, g/d
Suckling (birth to weaning)	−0.376	0.104	<0.01	4.02	1.01	<0.01	5.3
Nursery (Weaning to day 66)	−1.411	0.376	<0.01	14.63	3.61	<0.01	5.2
Grow-Finish	−2.374	0.690	<0.01	19.35	6.52	<0.01	4.1
Overall (weaning to finish)	−2.207	0.518	<0.01	18.19	4.89	<0.01	4.1
Carcass characteristics
Hot carcass weight, kg	0.005	0.023	0.831	−0.18	0.22	0.403	NA
Adjusted HCW (day 174)4, kg	−0.136	0.040	<0.01	1.02	0.38	<0.01	3.8
Backfat, mm	−0.048	0.011	<0.01	0.45	0.11	<0.01	4.7
Loin depth, mm	0.046	0.025	0.074	−0.61	0.24	0.012	6.7
Lean percentage5, %	0.032	0.007	<0.01	−0.31	0.07	<0.01	4.8
Lean growth rate, g/d	−0.192	0.131	0.143	0.73	1.25	0.560	NA

¹Parity and parity × parity served as covariates in the statistical model, the coefficient of parity and parity × parity are reported in the table.

²Calculated from the quadratic (a) and linear (b) coefficients: b/(-2a). (NA: there was no optimal parity when P (quadratic) > 0.10.

³Adjusted finishing (day 167) weight = Average daily gain (ADG, g/d) grow-finish × (167 d – actual age) × 1.16 + finishing BW, kg.

⁴Adjusted HCW (day 174) = (Hot carcass weight, HCW, kg – weaning weight × 0.7, kg)/(age at slaughter – age at weaning) × (174 d – age at slaughter) × 1.16 + HCW, kg.

⁵Lean percentage, % = 66.86 − 0.6549 × backfat depth (mm)+ 0.0207 × loin depth (mm).