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Evonik Animal Nutrition
Optimal sulfur amino acids: lysine ratio and bioavailability of DL-Met and liquid MHA-FA in 10-20 kg pigs
Published: August 2, 2018
By: Dr. John K. Htoo, Evonik Nutrition & Care GmbH
• The standardized ileal digestible (SID) sulfur amino acids (SAA) requirement for 10-20 kg PIC pigs was estimated to be 0.77 % to optimize ADG and 0.82 % to minimize FCR, which is approximately 29 % higher than the NRC (1998) recommendation. • The SID Lys requirement for 10-20 kg PIC pigs was estimated to be 1.35 % to minimize FCR. This estimate is approximately 25 % higher than the NRC (1998) recommendation. • By correlating the SID requirement estimates for SAA and Lys, the optimal SID SAA:Lys ratio in starter pig diets was estimated to be approximately 60 %. • The results of this study confirm that the amino acids (AA) requirement of today’s high lean pig genetics is considerable higher than currently suggested. Furthermore, the results of this study showed that 100 parts of liquid MHA-FA can be replaced with 65 parts of DL-Met in pig diets without affecting growth performance. |
Introduction and objectives
Methionine (Met) is considered the 2nd or 3rd limiting AA in typical swine diets. Because cystine (Cys) can be converted from Met but not vice versa, the amount of Met required in the diet also depends on dietary Cys content. Thus, it is important to know the optimal level of Met + Cys or SAA in addition to Met requirement. Furthermore, AA requirement of today’s high lean pig genetics is considerable higher than currently suggested (e.g. Kendall et al., 2008). Methionine is supplemented as dry DL-Met (99 % pure) or as liquid DL-Met hydroxy analog-free acid (MHA-FA, 88 % of 2 hydroxy-4-methylthiobutanoic acid). Some previous studies with starter pigs have reported a relative bioavailability (RBV) for MHA-FA of about 65 % compared with DL-Met on product basis (e.g. Kim et al., 2006). However, there is still ongoing discussion about the RBV of Met sources.
The objective of this study was to estimate the optimal dietary SID SAA:Lys ratio based on the dietary levels of SAA and Lys that optimize performance of 10 to 20 kg pigs. The additional goal was to test whether similar pig performance is achieved when 100 parts of MHA-FA are replaced with 65 parts of DL-Met to supply Met in Met-deficient diets. This study was conducted at the commercial research farm of PigCHAMP Pro Europa, S. A., by Dr. J. Morales from the PigCHAMP Pro Europa, S. A., Segovia, Spain.
Experimental design
A 21-d dose-response growth assay was conducted with 432 high lean PIC pigs (GP1050; initial body weight (BW) = 9.6 ± 0.80 kg]. Pigs were housed in 3 identical temperature controlled rooms having 72 pens in total and blocked by gender, littermate, initial BW and room, and allotted to 12 dietary treatments with 6 pigs (3 barrows and 3 gilts) per pen and 6 pen replicates per treatment.
Table 1: Composition of SAA-deficient, Lys-deficient and high AA diets (as-is basis)
1 Diets 2, 3 and 4 were obtained by adding graded levels of DL-Met (0.078, 0.157 and 0.235 %) to diet 1. Diets 10, 11 and 13 were produced by adding graded levels of liquid MHA-FA (0.120, 0.241 and 0.361 %) to diet 1.
2 Diets 6, 7 and 8 were obtained by adding graded levels of L-Lys·HCl (0.18, 0.31 and 0.44 %) to diet 5.
3 Analyzed values.
2 Diets 6, 7 and 8 were obtained by adding graded levels of L-Lys·HCl (0.18, 0.31 and 0.44 %) to diet 5.
3 Analyzed values.
Firstly, a SAA-deficient (diet 1), a Lys-deficient (diet 5) and a high-AA (diet 9) were formulated based on corn, wheat, soybean meal, whey powder and fish meal (Table 1) using analyzed ingredient AA contents and published SID coefficients (AminoDat® 3.0) to exceed requirements of AA other than SAA (in diet 1) and Lys (in diet 5), and to be isocaloric. Diets 2, 3 and 4 were obtained by supplementing graded levels of DL-Met (0.078, 0.157 and 0.235 %) to diet 1 at the expense of corn starch. Diets 6, 7 and 8 were obtained by supplementing graded levels of L-Lys·HCl (0.18, 0.31 and 0.44 %) to diet 5 at the expense of corn starch.
Additionally diets 10, 11 and 13 were produced by supplementing graded levels of MHA-FA (0.120, 0.241 and 0.361 %) to diet 1 based on DL-Met to MHA-FA ratio of 65:100 on product basis. Added levels of Met sources and contents of Lys and SAA in all diets are given in Table 2. The analysis of the experimental diets confirmed that the contents of supplemental AA were very close to the calculated values.
Table 2: Added levels of Met sources and contents of Lys and SAA in the diets
Individual BW and feed disappearance were recorded weekly to calculate average daily gain (ADG), average daily feed intake (ADFI), and FCR during the 21-d experimental period. Growth responses of pigs fed diets 1 to 4 and 9 were used to estimate SAA requirement while dose responses of pigs fed diets 5 to 9 were used to derive Lys requirement. The effects of dietary Met sources on pig performance were evaluated by comparing the responses of diets 1 to 4, 10, 11 and 12.
Data were analyzed by ANOVA using the GLM procedure of SAS with room (block), initial BW and dietary treatments included in the model. Based on the best fit of the ADG and FCR data, curvilinear-plateau regression [y = L + U + (R – x)2, where (R – x) is zero at values of x > R; Robins et al., 2006] was conducted to estimate the requirements of SAA and Lys.
Results
The effects of dietary SAA level on performance are given in Table 3. During the 21-d period, the ADG, final BW and FCR increased linearly (P<0.05) as the SID SAA level improved and seems to optimize at the SID SAA of 0.78 % (Table 3). The ADFI was not affected by the dietary treatments.
Table 3: Effect of dietary SAA levels on performance of starter pigs (10-20 kg BW)
The dietary SID SAA level to maximize ADG was 0.77 % based on curvilinear-plateau regression analysis (Figure 1). Using FCR as response criterion the curvilinear-plateau regression estimated the SID SAA requirement of 0.82 % (Figure 1) which is approximately 29 % higher than the NRC (1998) recommendation.
Figure 1: Fitted curvilinear-plateau plots of ADG and FCR as functions of SID SAA requirement
Performance responses to graded levels of Lys are shown in Table 4. During the 21-d period, the ADG, final BW and FCR improved linearly (P<0.001) as the SID Lys level increased (Table 3). The ADFI was not affected by the dietary treatments. Using ADG as a response criterion, the SID Lys requirement was estimated to be higher than the highest tested level of 1.38 % (Figure 2). Using FCR as response criterion the curvilinear-plateau regression estimated the minimum FCR to be at 1.35 % SID Lys (Figure 2), which agrees well with Kendall et al. (2008) who also estimated the SID Lys requirement for 11-19 kg PIC pigs to be 1.35 %.
Table 4: Effect of dietary Lys levels on performance of starter pigs (10-20 kg BW)
Figure 2: Fitted curvilinear-plateau plots of ADG and FCR as functions of SID Lys requirement
Interestingly the optimal FCR achieved in both SAA and Lys titration studies were identical. By correlating the SID requirement estimates for SAA and Lys both derived by using FCR as the same response criterion, an optimal SID SAA:Lys ratio was estimated to be 60.7 % in starter pigs used in this study. This estimate is in close agreement with Gaines et al. (2005) who also reported that the optimum SID SAA:Lys ratio for 8-26 kg PIC pigs was approximately 60 %.
Table 5: Effect dietary DL-Met or MHA-FA levels on performance of starter pigs (10-20 kg BW)
P1 = Linear effect of DL-Met; P2 = Linear effect of liquid MHA-FA. P3 = DL-Met vs. liquid MHA-FA.
During the 21-d period, graded levels of DL-Met supplementation to the Met-deficient diet improved both ADG and FCR, however graded levels of supplementation with liquid MHA-FA only improved FCR but did not significantly affect ADG (Table 5). Overall, growth performance was not significantly different among the two corresponding Met-supplemented groups, indicating that 100 parts of MHA-FA can be replaced with 65 parts of DL-Met without affecting growth performance.
Source
Morales, J. (2010): Evaluation of optimum SID sulfur containing amino acids to lysine ratio and bioavailability of DL-Met and liquid MHA-FA in diets for starter (10-20 kg) pigs. Evonik Degussa trial report No. 02.63.09001.
References
AminoDat® 3.0. Platinum version, 2005. Evonik Degussa GmbH,Hanau-Wolfgang,Germany.
Gaines, A. M., G. F. Yi, B. W. Ratliff, P. Srichana, D. C. Kendall, G. L. Allee, C. D. Knight, and K. R. Perryman (20059:
Estimation of the ideal ratio of true ileal digestible sulfur amino acids:lysine in 8- to 26-kg nursery pigs. J. Anim. Sci. 83:2527-2534.
Estimation of the ideal ratio of true ileal digestible sulfur amino acids:lysine in 8- to 26-kg nursery pigs. J. Anim. Sci. 83:2527-2534.
Kendall, D. C., A. M. Gaines, G. L. Allee, and J. L. Usry (2008): Commercial validation of the true ileal digestible lysine requirement for eleven- to twenty-seven-kilogram pigs. J. Anim. Sci. 2008. 86:324-332.
Kim, B. G., Lindemann, M. D., M. Rademacher, J. J. Brennan, and G. L. Cromwell (2006): Efficacy of DL-methionine hydroxy analog free acid and DL-methionine as methionine sources for pigs. J. Anim. Sci. 84:104-111.
NRC (1998): Nutrient Requirements of Swine, 10th revised edn.NationalAcademyPress,Washington,DC.
Robbins, K.R., A.M. Saxton and L.L. Southern (2006): Estimation of nutrient requirements using broken-line regression analysis. J. Anim. Sci. 84 (E. Suppl.):E155-E165.
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