Effects Of Lysine And Protein Intake During Lactation On Subsequent Reproductive Performance In Multiparous Sows

The effect of lysine and protein intake over two parities on lactation and subsequent reproductive performance were conducted by a 2×2 factorial arrangement with 2 levels of total lysine (0.95% and 1.10%) and 2 levels of crude protein (17.5% and 19.0%). 108 sows were assigned randomly into four groups. Sows were maintained on the same lactation dietary treatment through two consecutive lactations, and all sows were fed with common gestation diet (14.6% CP and 0.68% lysine) from weaning to next farrowing. Litter size was standardized to 10 to 12 pigs in the first lactation and to 9 to 11 pigs in the second lactation within 24h of parturition by cross-fostering. The main results were as follows:(1) In the first lactation, there were no significant difference between two lysine and two proetin concentrations on sow ADFI. Compared with the 17.5% crude protein groups, 19.0% crude protein groups lysine intake and CP intake were significantly increased by 5.03% (P>0.05) and 11.53% (P<0.01), respectively. Lysine intake of the 1.10% Lysine groups were increased by 16.47% compared with the 0.95% Lysine groups (P<0.01). A significant interaction between dietary lysine and crude protein levels was observed on body weight at weaning and body weight loss of sows (P<0.05). The lactation weight loss of 19.0% crude protein groups was decreased by 24.11% (P=0.0516) compared with 17.5% crude protein groups, the lactation weight loss of 17.5%CP, 0.95% Lys group sows was significantly (P<0.05) higher than 17.5% CP, 1.10% Lys group and 19.0% CP, 0.95% Lys group, among the four treatments. No significant effect on litter growth performance was shown between groups treated with different protein and lysine levels.(2) In the second lactation, there were no significant difference between two lysine and two proetin concentrations on sow ADFI. Compared with the 17.5% crude protein groups, 19.0% crude protein groups sows increased crude protein intake by 7.76% (P<0.05). Compared with the 0.95% Lysine groups, 1.10% Lysine groups sows increased lysine feed intake by 6.92% (P<0.01). The body weight loss of 1.10% lysine groups sows were decreased significantly than 0.95% lysine groups(P<0.01). There was no significant effect on litter growth performance of different protein and lysine levels.(3) No significant effect was observed on subsequent parity performance between protein levels of different diets. The stillborns of subsequent parity of 1.10% lysine groups sows were increased significantly (P<0.05) compared with 0.95% lysine groups. A significant (P<0.05) interaction between dietary lysine and protein levels was observed on the stillborns.(4) Compared with the 17.5% crude protein groups, sow culling rate were decreased by 14.29% (P<0.05) in farrowing to estrus of the second lactation, and by 18.42% in all experiment stage of the 19.0% CP groups. There was no significantly effect on sow culling rate between lysine levels of different diets. In the farrowing to estrus of the second lactation, sow culling rate of 17.5% CP, 1.10% Lys group was significantly higher (P<0.05) than two 19.0% crude protein treatments.(5) Compared with the 17.5% crude protein groups, the serum urea nitrogen (SUN) concentration of sows in two 19.0% crude protein groups was increased 1.67%, 22.21% (P<0.05), 10.71% and 12.92% on the farrowing day 0, day 7, day 14 and day 21 of lactation, respectively. No significant difference of SUN concentration was observed between two lysine concentrations.(6) Compared 19.0% crude protein groups with 17.5% crude protein groups, there were increased by 0.92%, 14.34%, 9.83% and 18.03% in the apparent nitrogen digestibility, nitrogen intake, nitrogen excreted in manure and urine respectively, with no significant difference (P>0.05). Compared 1.10% Lysine groups with 0.95% Lysine groups during the lactation, there were increased by 1.18% in the apparent nitrogen digestibility, decreased by 3.29%, 7.44% and 4.39% in nitrogen intake, nitrogen excreted in manure and urine respectively, with no significant difference (P>0.05).The following conclusion of this study can be drawn from:(1) The effects of lysine intake towards lactation weight loss largely depend on feed intake. Increasing lysine intake under low feed intake condition is beneficial for reducing lactation weight loss, while increasing lysine intake under high feed intake condition give rise to increased lactation weight loss probably for the addition of lysine induced unbalanced dietary amino acid.(2) Increasing protein intake may be beneficial to reduce the lactation weight loss and the culling rate of sows, improve the subsequent reproduction performance of sows.