Table 2.

Effect of Met:Lys ratio in the lactation diet on the performance of sows

Items	Met:Lys				SEM	P-value
	0.27	0.37	0.47	0.57		Linear	Quadratic	Feed
Basic information
No. of sows	33	32	32	33
Culleda during lactation	4	1	–	1
Average body weight, kg	266.70	266.50	266.70	266.40	1.64
Average parity	4.40	4.10	4.00	4.38	0.07
BW of sows, kg
Day 110 of lactation	268.9	266.4	265.8	266.8	1.7	0.70	0.80	0.93
Parturition	264.8	262.3	261.8	262.8	1.7	0.70	0.81	0.93
Weaning	245.2	243.9	244.5	247.3	1.8	0.70	0.77	0.92
Loss during lactation	−19.6	−18.4	−17.2	−15.4	1.4	0.30	0.57	0.77
WEI of sows, d
No. of sows	29	31	31	32
Within 1 week	4	5	4	5	0.13	0.97	0.99	0.93
After 1 week	6	8	5	6	0.51	0.80	0.73	0.22
Estrus rate of sows, %b
Within 1 week	89.66	77.42	93.55	90.63		0.66	0.86	0.22
After 1 week	96.55	100.00	100.00	100.00		0.20	0.26	0.35
Sow backfat thickness, mm
No. of sows	32	32	32	33
Day 110 of lactation	15.72	15.97	15.72	15.33	0.24	0.50	0.65	0.83
Parturition	14.94	15.38	15.19	14.76	0.27	0.80	0.69	0.86
No. of sows	29	31	32	33
Weaning	14.41	15.29	14.94	14.42	0.26	0.90	0.40	0.57
Loss during lactation	−0.59	−0.19	−0.25	−0.33	0.21	0.70	0.81	0.92
Lactation performance, kg
Total milk yieldc	203.59	207.18	213.29	210.94	3.26	0.56	0.80	0.70
Average daily milk yield	11.10	11.34	11.62	11.44	0.08	0.59	0.85	0.97

SEM standard error of the mean, BW body weight, WEI weaning to estrous interval; Annotation: significance test for estrus rate of each group derived from the chi-square test; N indicates the number of sows

^aThe sows eliminated in each group for death, lameness, limb hoof disease and so forth during lactation

^bSignificance test for estrus rate of each group derived from the chi-square test

^cThe result of total milk yield during the whole lactation period is shown as Lsmeans and derived from the mixed procedure of SAS (8.0). The formula for the calculation of total milk yield is total milk yield (kg) = piglet ADG × litter size × lactating days × 4 [13]