Utilization of crystalline or protein-bound lysine for growth and carcass traits of barrows and gilts fed individually or in groups1

Abstract

An experiment consisting of two 4-wk trials was conducted to determine Lys use for growth and carcass traits in barrows and gilts fed individually or in groups. One hundred twelve growing pigs (56 barrows and 56 gilts; average initial BW of 18.6 kg) were used in each trial. Pigs were fed individually or in groups of 3. There were 28 pigs individually penned, and 84 pigs in 28 pens (3 pigs/pen). There were 2 replications per treatment in each trial for a total of 4 replications. Dietary treatments consisted of a corn-soybean meal (SBM) basal diet (0.48% Lys) and diets containing 0.56%, 0.65%, and 0.74% standardized ileal digestible (SID) Lys that were achieved by adding Lys to the basal diet from either SBM or crystalline source as L-Lys HCL (CLys). At the end of each trial, all pigs were scanned using real-time ultrasound to determine 10th-rib back fat depth and LM area, and fat-free lean gain (FFLG) was calculated. Blood samples were taken from all pigs weekly to determine plasma urea N (PUN). Pigs fed CLys and Lys from SBM were not different in final BW, ADG, ADFI, or G:F. The ADG and G:F increased linearly (P < 0.01) as dietary Lys concentration increased. The SID Lys intake increased linearly (P < 0.01) as dietary Lys concentration increased and was not different when comparing pigs fed diets with CLys or SBM. The amount of SID Lys required per unit of growth or BW gain increased linearly (about 13 to 15.50 g/kg) in pigs fed either CLys or SBM Lys. Pigs fed individually had a greater (P < 0.05) ADG (0.59 vs. 0.57 kg) and ADFI (1.36 vs. 1.29 kg) than pigs fed in groups. The SID Lys intake was greater (P < 0.05) in pigs fed individually in comparison with pigs fed in a group (8.51 vs. 8.06 g/d). Fat-free lean gain and LM area increased (P < 0.01) as dietary Lys concentration increased regardless of Lys source. Pigs fed CLys diets had a greater (P < 0.05) LM area than pigs fed SBM at 0.74% SID Lys. Gilts had a greater (P < 0.01) LM area (14.28 vs. 13.58 cm(2)) and FFLG (264 vs. 245 g/d) than barrows. Pigs fed individually with CLys had less (P < 0.01) PUN than pigs fed Lys from SBM. Barrows fed individually had less (sex × feeding method, P < 0.01) PUN than gilts (26.75 vs. 29.32 g/100 mL). The results indicate that Lys from SBM-bound and CLys source were utilized similarly for growth and carcass traits regardless of sex or feeding method.

Body composition, tissue deposition, and lysine utilization for protein deposition of barrows and gilts fed crystalline or protein-bound lysine1

“…For this reason, under the conditions of this study, SID Lys intake/PD may not be an accurate variable to estimate Lys utilization between sexes, likely because the amount of Lys deposited in empty-body protein was numerically lower in barrows than gilts (4.90 and 5.27 g/d, representing 6.68% and 5.55% Lys in PD, respectively). This greater Lys deposition:SID Lys intake ratio may be attributed to the greater Lys requirements of gilts for lean gain; in fact, these gilts (Colina et al, 2013). There are few data regarding deposition rates of AA in pigs when comparing crystalline and protein-bound Lys.…”

“…Pigs had ad libitum access to 1 of 7 experimental diets and water throughout each 28-d trial. The 7 diets used were described by Colina et al, (2013) and consisted of a basal diet (0.48% Lys) containing protein-bound Lys and diets with 0.56%, 0.65%, and 0.74% standardized ileal digestible (SID) Lys that were achieved by adding Lys to the basal diet from either SBM or CLys as l-Lys·HCl in place of cornstarch. The SID Lys content in the SBM (46.5% CP) used in the diets was 2.72%.…”

“…absorption of crystalline Lys (CLys) utilization relative to AA derived from intact protein has been shown (Yen et al, 2004). Other studies have demonstrated the lack of difference between pigs fed below the requirement with l-Lys·HCl or soybean meal (SBM)-bound Lys for PD (Susenbeth et al 1994;Liebert, 1995;Colina et al, 2013). Moreover, Heger et al (2009) indicated that pigs with a greater PD rate do not utilize Lys more efficiently compared to pigs with less PD.…”