Evaluation of the order of limitation of lysine, threonine, and valine, as determined by plasma urea nitrogen, in corn-soybean meal diets of lactating sows with high body weight loss1,2,3

Abstract

Three experiments were conducted to evaluate the order of limitation for Lys, Thr, and Val in corn-soybean meal diets of lactating sows experiencing high BW loss during lactation. Plasma urea N (PUN) was used as the response criterion. Experimental diets used in all 3 experiments were derived from the basal diet (BSL) formulated to 0.51% Lys using corn and soybean meal as the only sources of AA. The BSL diet was formulated by diluting a reference corn-soybean meal diet (17.2% CP, 0.90% Lys, 0.65% Thr, 0.82% Val, and 0.28% Met) with cornstarch, sucrose, and soybean oil to maintain the same ratio of corn to soybean meal. Experiment 1 was conducted to determine whether PUN is sensitive to dietary Thr and Val levels and whether a 4-d feeding period was adequate to observe a PUN response. The results demonstrated that PUN could be used as the response criterion and that a 4-d feeding period was adequate. Experiment 2 was conducted to determine whether Thr or Val was most limiting in the BSL diet. Dietary treatments used in Exp. 2 consisted of 1) BSL supplemented with 0.09% L-Lys and 0.02% DL-Met, which served as the negative control (NC2); 2) NC2 plus 0.14% L-Thr (NC2 + T); 3) NC2 plus 0.17% L-Val (NC2 + V); and 4) NC2 plus 0.14% L-Thr and 0.17% L-Val (NC2 + T + V). The value for PUN was lower for the NC2 + T and NC + T + V treatments compared with the NC2 and NC2 + V treatments (5.18 and 5.33 vs. 6.43 and 6.62; P < 0.01), indicating that Thr was most limiting in the NC2 diet. Experiment 3 was conducted to determine whether Thr or Lys was most limiting in the BSL diet. Dietary treatments used in Exp. 3 consisted of 1) the BSL diet supplemented with 0.02% DL-Met only, which served as the negative control diet (NC3); 2) the NC3 diet supplemented with 0.20% L-Lys (NC3 + L); 3) the NC3 diet supplemented with 0.14% L-Thr (NC3 + T); and 4) the NC3 diet supplemented with 0.20% L-Lys and 0.14% L-Thr (NC3 + L + T). The value for PUN was lower for NC3 + L compared with NC3 and NC3 + T (7.45 vs. 9.11 and 8.45 mg/dL; P < 0.01), and PUN for NC3 + L + T was lower than the PUN measured for NC3 + L (5.94 vs. 7.45; P < 0.01). The results of Exp. 2 and 3 indicate that Lys was first-limiting and Thr second-limiting in the BSL diet.

The effect of the ratio of standardized ileal digestible lysine to metabolizable energy on growth performance, blood metabolites and hormones of lactating sows

“…Plasma urea nitrogen can represent a sensitive response criterion for protein utilization [34] and its concentrations decreased quadratically with increasing dietary lysine intake [35]. Similar results were found in Exp.…”

Effect of dietary valine levels on the growth performance, feed utilization and immune function of juvenile golden pompano,Trachinotus ovatus

“…This is supported by the significant changes in serum urea concentration between different valine groups in the present study, suggesting an imbalance of dietary amino acid concentration would alter the metabolisms of protein. The increase in urea could be explained by high catabolism of protein and the poor utilization of dietary protein by fish (Soltwedel, Easter, & Pettigrew, ). This could be supported by the changes in intestinal amylase and pepsin activities.…”

Ideal amino acid balance for sows during gestation and lactation1

“…A paritysplit feeding system would be a practically feasible way of applying dynamic ideal protein concept in feeding lactating sows. Soltwedel et al (2006) evaluated the limiting order of AA in a corn-soybean meal lactation diet for sows losing about 25 kg of BW during a 21-d lactation. This would correspond to about 30% level of tissue mobilization as calculated by Kim et al (2001a), that is, 30% of the AA output in milk being provided by tissue protein breakdown in the sows.…”