HUE UNIVERSITY UNIVERSITY OF AGRICULTURE AND FORESTRY DAO THI BINH AN ESTIMATION OF THE STANDARDIZED ILEAL DIGESTIBLE LYSINE REQUIREMENT AND OPTIMAL SULPHUR AMINO ACIDS TO LYSINE RATIO FOR HYBRID PIGS [(PIETRAIN x DUROC) x (LANDRACE x YORKSHIRE)] FROM 10 – 20 KG AND 30 – 50 KG Specialization: Animal Sciences Code: 9.62.01.05 SUMMARY OF PHD THESIS IN AGRICULTURAL SCIENCE HUE - 2019 This work was completed at: Hue University of Agriculture and Forestry, Hue University Science instructor: Assoc.Prof Dr Ho Trung Thong Prof Dr Vu Chi Cuong Reviewer 1: ……………………………………………………………………………………………… Reviewer 2: …………………………………………………… ……………………………………… Reviewer 3: …………………………………………………… ……………………………………… The thesis was defended at the Council of thesis assessment of Hue University: Council held at: Le Loi street, Hue City, Thua Thien Hue province, at…… on ……/ ……./2019 Theses can be further referred at: National Library Center for Information and Library of Hue University of Agriculture and Forestry, Hue University INTRODUCTION Background Lysine (Lys) is generally the first limiting amino acid (AA) in practical pig diets, and consequently, its requirement has been most extensively studied (Ball et al., 2007) There is considerable variation in the reported Lys requirements which may be due to differences in the lean gain potential of the pig genetics used The ability of protein accumulation and lean meat accumulation are different among pig breeds, and also different during the growth stages in the same pig breed The advances in nutrition and feed industry had played an important part in making a sufficient of Lys requirement in the dietary for the range of growth stages of pigs In case of lack of adjustment to the effect of increase leanness on the pig’s lysine needs, dietary lysine deficiency may occur, then limiting the development of pig genetic potential Therefore, it is necessary to adjust lysine in the dietary to ensure maximum growth in pigs Along with Lys requirement in the pig dietary, sulfur amino acid (SAA) (methionine and cysteine) is considered as the second or third limiting amino acid in the pig diets However, up to now, there is a lack of studies that focused on the standardized ileal digestible sulfur amino acid (SID SAA) in comparison with standardized ileal digestible Lys (SID Lys), and also the results in those studies were varied In Vietnam, previous studies of AA requirement for pigs were often focused on the needs of Lys, not considering the optimal proportions of others AA to Lys, and often expressed in total AA level In addition, the subjects of these studies were pure pig breeds, domestic pig breeds and hybrid pig breeds between foreign breeds and domestic breeds The commercial pigs with and foreign breeds have not been studied yet The conducting studies to determine the requirements for ileum digestible AA for exotic breeds in Vietnam is necessary Therefore, the study “Estimation of standardized ileal digestible lysine requirement and optional sulfur amino acids to lysine ratio for hybrid pigs [(Pietrain x Duroc) x (Landrace x Yorkshire)] from 10-20 kg and 30-50 kg” were conducted OBJECTIVES - Determining the SID Lys requirements for commercial pigs [(Pietrain × Duroc) × (Landrace × Yorkshire)] in the periods 10-20kg and 30-50kg - Determining the optional ratio of SID SAA Lys to SID Lys of commercial pigs [(Pietrain × Duroc) × (Landrace × Yorkshire)] 10-20kg and 30-50kg periods SCIENTIFIC AND PRACTICE MEANING - The study results of this thesis have contributed to data on the SID Lys requirements and the optional ratio of SID SAA:Lys for pigs [(Pietrain x Duroc) x (Landrace x Yorkshire)] 10-20kg and 3050kg periods in husbandry condition in Vietnam; - The results of this study would provide information to the optimal formulation in the feed manufacturers, especially in the feed industry NEW CONTRIBUTION OF THESIS - This was the first time in Vietnam, the SID Lys requirement of fourth breed commercial hybrid pigs [(Pietrain × Duroc) × (Landrace × Yorkshire)] 10-20kg and 30-50kg periods was determined - This was the first time to identify the optimal SID SAA:Lys ratio for fourth breed commercial hybrid pigs [(Pietrain × Duroc) × (Landrace × Yorkshire)] of 10-20kg and 30-50kg periods - The results of this study have contributed to the database to build optimal diets for commercial pigs which could be based on the balancing lysine with non-necessary amino acids at SID as well as other nutrients in the formula THESIS STRUCTURE The thesis consisted of 91 pages and chapters Chapter 1: Introduction (04 pages), chapter 2: Literature review (26 pages), chapter 3: Materials and methodology (19 pages), chapter 4: Results and discussion (24 pages), chapter 5: Conclusion and recommendations (2 pages) The thesis also included 30 tables, 15 diagrams and 147 references (25 Vietnameses) CHAPTER 1: LITERATURE REVIEW 1.1 Overview of research on the SID AA requirement for the pig in the world Nowadays, feed evaluation is based on the digestibility percentage of nutrients that there have been used in numerous countries Formulating diets that are based on feed digestibility will demonstrate a higher accuracy than the total nutrient composition The AA requirement for the pig was studied for each AA and also for each growth stage of the pigs The standardized ileal digestible lysine requirements for pigs In recent years, numerous researches have been done to determine the SID Lys requirement for pigs For example, at the growth stage of 12-24kg Yi et al (2006) reported that the requirement of SID Lys was 1.32% Ken et al (2008) showed that using SID Lys at 1.30% or 19g/kg weight gain was necessary for the optimal growth rate of pigs of 12-27kg period In the case of a correlation between SID Lys and dietary energy, that SID Lys was 3.81g/Mcal ME Pigs from 11-19kg, the use of SID Lys at 1.35% ensured optimal pig growth (Kendall et al., 2008) Meanwhile, NRC (2012) recommends SID Lys requirements for the pig at 11-25kg was 1.23%, which was lower than the above studies The difference in the results of determining Lys requirements in growth pigs may be due to numerous causes, including the establishment of a diet which based on the total AA instead of SID AA (Stein et al., 2007b), statistical analysis methodology (Robbins et al., 2006), gender (Baker, 1986), or genotype (Schneider et al., 2010) NRC (2012) recommended that SID Lys for growth pig of 25-50kg period was 0.98% Based on broken-line regression, Li et al., (2012) found that ratio between SID Lys and ME at 3.0; 2.43; and 2.2 were the best for growth performance at 29-47kg, 54-76kg and 84-109kg periods, respectively Bergstrom et al., (2010) conducted four experiments with castrated boars and females (balance mixed sex) to estimate the Lys requirement for different growth stages (PIC TR4 x 1050), the variety from 37-129kg The results showed that the ratio between SID Lys and ME at 2.69; 2.35; 2.09 and 1.79 g/Mcal ME were the best for growth performance and highest rate income per feed cost (Bergstrom et al., 2010) In addition, Shelton et al., (2009) [126] also reported that SID Lys requirements for gilts (55-80kg) were 20g Percentage of sulfur amino acids to SID Lys Sulfur amino acid (methionine and cysteine) is considered as the second or third limiting AA in the pig diets Numerous studies have been done in these years to determine the requirement for total SAA, methionine and cysteine requirement for pigs Typically, methionine is accounted for 50% in total SAA (according to the NRC, 48% by volume); however, the recent studies showed that methionine might be accounted for a higher percentage (55% by weight or 50% by molecular weight) in comparison with cysteine Dean et al., (2007) found that the total requirement of SAA for the piglets of 6-12kg was 10.1% g/kg weight gain or 54% Lys Gaines et al., (2005) reported that the rate of total SAA to Lys was 57-61%, which depending on the monitoring criteria and the stopping assessment method of 8-26kg pigs Yi et al., (2006) found that average optimal SAA: Lys ratio for an average daily gain (ADG) of 12-24kg pigs to be 58% In other studies, Schneider et al., (2-10) showed that the total SAA: Lys ratio to the pig from 10-20kg was ranging from 57% to 60% In addition, Gaines et al., (2004a, b) who done two independent experiments on pigs at 29-45kg and 45-68kg periods found that the optimal SAA: Lys ratio at those stages were 60% Similarly, Lawrence et al., (2005) also reported that the optimal SAA: Lys ratio was 60% for pigs from the 30-60kg period In a recent study of Capozzalo et al., (2017), supplemented with E.coli strains with the high requirement of SAA in the diets to assess their influence on SID SAA:Lys ratio The results showed of that the SID SAA:Lys ratio was no significant difference between diets with/without supplimentation E.coli 1.2 Overview of research on the SID AA requirement for the pig in Vietnam In Vietnam, the information on the AA requirement as well as SID Lys for major pig breeds in Vietnam is still limited Studies on AA requirement often focused on Lys requirement and usually represented as total AA Numerous studies on total lysine requirements, total methionine, total cysteine, and total Threonine were conducted on the domestic pig breeds, exotic breeds and the hybrid between them Recently, there was a study on SID Lys in pigs at the growth to finishing commercial blood pig breeds, not on the piglets This study was calculated the non-substituted AA based on the reference public in the world Currently, there has been no announcement about the digestible AA requirement in piglets in Vietnam In the current feed pig database, there is also no information on the SID AA That leads to a mission that determines the SID AA requirement for main pig breeds in husbandry conditions in Vietnam is extremely necessary Chapter II: MATERIALS AND METHODS 2.1 Materials A total of 400 crossbred pigs [(Pietrain x Duroc) x (Landrace x Yorkshire)] (abbreviation PiDu x LY) Materials used to mix diets include corn, broken rice, rice bran, soya bean meal, full-fat soya, protein concentrate, whey powder, palm oil, corn starch, DCP 19% (Dicalcium phosphate), limestone, mineral‐vitamin premix, salt, and crystalline amino acids 2.2 Location and time The experiment was conducted from February 2015 to December 2015 at the Center for Animal Research and Practice under the Hue University of Agriculture and Forestry – Hue University 2.3 Subjects - Estimation of SID lysine requirement for 10 – 20 kg pigs - Estimation of SID lysine requirement for 30 – 50 kg pigs - Estimation of optimal SID SAA:Lys ratio for 10–20 kg pigs - Estimation of optimal SID SAA:Lys ratio for 30–50 kg pigs 2.4 Methodology 2.4.1 Estimation of SID Lys requirement for 10–20 kg pigs A total of 108 crossbred pigs (PiDu x LY; balanced mixed sex) with an average initial BW of 11,8 kg were used in this experiment They were allotted to one of six treatments on the basis of initial BW with six replicate pens per treatment and three pigs per pen Six diets were obtained by supplementing graded levels of L‐Lysine HCl to create six dietary levels of SID Lys (0.90%, 0.10%, 1.10%, 1.20%, 1.30% and 1.40%) The experimental diets were formulated based on corn, broken rice, soya bean meal, full‐fat soya bean, soy protein concentrate and whey powder using analysed ingredient AA contents and published SID coefficients to meet or exceed minimum AA requirement (‘AMINODat 4.0 Platinum’ 2012; NRC 2012) Net energy (NE) in diets is the same (10,4 MJ/kg) Table 2.1 Ingredients composition of experimental diets of SID Lys requirement for 10–20 kg pigs (as-fed) Feed ingredients (%) Corn Soya bean meal Full fat soya Broken rice Soy protein concentrate Whey powder Palm oil Corn starch DCP 19% Limestone Mineral‐vitamin premix * Salt DL-Methionine L-Threonine L-Tryptophan L-Valine L-Lysine.HCl Total 0,9 Trial 52.69 15.00 5.12 8.00 7.26 5.00 2.94 1.00 0.86 0.55 0.30 0.52 0.28 0.24 0.09 0.14 100 1,0 Trial 52.69 15.00 5.12 8.00 7.26 5.00 2.94 0.872 0.86 0.55 0.30 0.52 0.28 0.24 0.09 0.14 0.128 100 SID Lys, % 1,1 1,2 Trial Trial 52.69 52.69 15.00 15.00 5.12 5.12 8.00 8.00 7.26 7.26 5.00 5.00 2.94 2.94 0.744 0.615 0.86 0.86 0.55 0.55 0.30 0.30 0.52 0.52 0.28 0.28 0.24 0.24 0.09 0.09 0.14 0.14 0.256 0.385 100 100 1,3 Trial 52.69 15.00 5.12 8.00 7.26 5.00 2.94 0.487 0.86 0.55 0.30 0.52 0.28 0.24 0.09 0.14 0.513 100 1,4 Trial 52.69 15.00 5.12 8.00 7.26 5.00 2.94 0.231 0.86 0.55 0.30 0.52 0.28 0.24 0.09 0.14 0.641 100 *1 kg Pre-Starter 500 (lợn – 20kg) contains 11.000.000 IU vitamin A; 1.500.000 IU vitamin D3; 40.000 mg vitamin E; 2.000 mg vitamin K3; 2.4000 mg vitamin B1; 4.000 mg vitamin B2; 27.000 mg vitamin B3; 13.500 mg vitamin B5; 4.000 mg vitamin B6; 1.700 mg vitamin B9; 35.000 mcg vitamin B12; 140.000 mcg biotin, 31.000 mg Fe; 20.000 mg Cu; 92.500 mg Zn; 40.000 mg Mn; 400 mg I; 420 mg Co; 225 mg Se; 120.000 mcg Cr Chemical analyses such as AA concentration, crude protein (CP) and dry matter (DM) were performed at the Laboratory of Evonik Singapore Crude fiber (CF), crude ash and ether extract (EE) were analysed according to AOAC (1990) at Central Laboratory, Faculty of Animal Sciences, College of Agriculture and Forestry - Hue University Table 2.2 Nutrient composition of experimental diets of SID lysine requirement for 10–20 kg pigs (% DM) Nutrient composition, % NE (MJ/kg) CP, % SID Lys, % SID Met, % SID M+C, % SID Thr, % SID Trp, % SID Ile, % SID Val, % SID Leu, % SID Arg, % SID, Phe, % SID His, % Calcium, % Avail P, % Sodium, % 0,9 10.40 19.08 0.90 0.53 0.79 0.83 0.29 0.68 0.90 1.33 1.17 0.79 0.45 0.70 0.35 0.25 SID Lys, % 1,1 1,2 10.40 10.40 19.08 19.08 1.10 1.20 0.53 0.53 0.79 0.79 0.83 0.83 0.29 0.29 0.68 0.68 0.90 0.90 1.33 1.33 1.17 1.17 0.79 0.79 0.45 0.45 0.70 0.70 0.35 0.35 0.25 0.25 1,0 10.40 19.08 1.00 0.53 0.79 0.83 0.29 0.68 0.90 1.33 1.17 0.79 0.45 0.70 0.35 0.25 1,3 10.40 19.08 1.30 0.53 0.79 0.83 0.29 0.68 0.90 1.33 1.17 0.79 0.45 0.70 0.35 0.25 1,4 10.40 19.08 1.40 0.53 0.79 0.83 0.29 0.68 0.90 1.33 1.17 0.79 0.45 0.70 0.35 0.25 The feed was provided with semi-ad libitum and free-drinking water Pigs were weighed at the beginning and at days, 14 days and the end of the experiment at 21 days to calculate the daily weight (ADG) by the week and by the entire experiment period Feed was weighed daily to calculate intake (FI) and weight gain/feed (G: F) by the week of the experiment and by the entire time of the experiment At the end of the experiment, 12 pigs (male: female ratio was 1: 1) for each treatment were selected for blood sampling and analysis of plasma urea nitrogen (PUN) content 2.4.2 Estimation of SID Lys requirement for 30–50 kg pigs A total of 72 crossbred pigs (PiDu x LY; balanced mixed sex) with an average initial BW of 28,85 kg were used in this experiment They were allotted to one of six treatments on the basis of initial BW with six replicate pens per treatment and two pigs (one barrow and one gilt) per pen Six diets were obtained by supplementing graded levels of L‐Lysine HCl to create six dietary levels of SID Lys (0.70%, 0.80%, 0.90%, 1.00%, 1.10% and 1.20%) In the diets with SID Lys levels from 0.7% to 1.00%, the feed ingredients were kept constantly and the only change is Lys content by adding L‐Lysine∙HCl To avoid imbalance in AA patterns and keep the ideal AA pattern in all diets, there was a small change in the feed compositions in the diets with SID Lys contents of 1.10% and 1.20% The experimental diets were formulated based on corn, broken rice, soya bean meal, full‐fat soya bean and whey powder using analysed ingredient AA contents and published SID coefficients to meet or exceed minimum amino acids requirement (‘AMINODat 4.0 Platinum’ 2012; NRC 2012) Net energy (NE) in diets is the same in level 10,2 MJ/kg in all diets Table 2.3 Ingredients composition of experimental diets of SID Lys requirement for 30–50 kg pigs (as-fed) Feed ingredients (%) Corn Soya bean meal Corn starch Rice bran Palm oil Dicalcium phosphate 19% Limestone Mineral‐vitamin premix* Salt DL-Methionine L-Threonine L-Tryptophan L-Valine L-Lysine.HCl Total 0,7 Trial 65.69 21.44 1.00 9.00 1.13 0.74 0.30 0.22 0.19 0.18 0.05 0.06 100 0,8 Trial 65.69 21.44 0.872 9.00 1.13 0.74 0.30 0.22 0.19 0.18 0.05 0.06 0.128 100 SID Lys, % 0,9 1,0 Trial Trial 65.69 65.69 21.44 21.44 0.744 0.615 9.00 9.00 1.13 1.13 0.74 0.74 0.30 0.30 0.22 0.22 0.19 0.19 0.18 0.18 0.05 0.05 0.06 0.06 0.256 0.385 100 100 1,1 Trial 69.12 27.3 0.487 1.15 0.69 0.30 0.22 0.18 0.14 0.04 0.03 0.340 100 1,2 Trial 65.67 30.43 0.231 0.50 1.13 0.68 0.30 0.22 0.21 0.17 0.04 0.04 0.380 100 *1 kg Pre-Starter 500 (20 – 40kg) contains 9.000.000 IU vitamin A; 1.300.000 IU vitamin D3; 33.000 mg vitamin E; 2.000 mg vitamin K3; 2.4000 mg vitamin B1; 3.000 mg vitamin B2; 25.000 mg vitamin B3; 12.000 mg vitamin B5; 3.300 mg vitamin B6; 1.500 mg vitamin B9; 35.000 mcg vitamin B12; 125.000 mcg biotin, 31.000 mg Fe; 30.000 mg Cu; 92.500 mg Zn; 31.000 mg Mn; 460 mg I; 420 mg Co; 180 mg Se; 120.000 mcg Cr Table 2.4 Nutrient composition of experimental diets of SID Lys requirement for 30–50 kg pigs (% DM) Nutrient composition, % NE (MJ/kg) CP, % SID Lys, % SID Met, % SID M+C, % SID Thr, % SID Trp, % SID Ile, % SID Val, % SID Leu, % SID Arg, % SID, Phe, % SID His, % Calcium, % Avail P, % Sodium, % 0,7% 10.23 16.07 0.70 0.41 0.64 0.67 0.21 0.55 0.70 1.16 0.95 0.66 0.38 0.66 0.31 0.10 SID Lys, % 0,9% 1,0% 10.23 10.23 16.07 16.07 0.90 1.00 0.41 0.41 0.64 0.64 0.67 0.67 0.21 0.21 0.55 0.55 0.70 0.70 1.16 1.16 0.95 0.95 0.66 0.66 0.38 0.38 0.66 0.66 0.31 0.31 0.10 0.10 0,8% 10.23 16.07 0.80 0.41 0.64 0.67 0.21 0.55 0.70 1.16 0.95 0.66 0.38 0.66 0.31 0.10 1,1% 10.20 18.35 1.10 0.42 0.68 0.71 0.22 0.64 0.75 1.32 1.10 0.77 0.44 0.66 0.31 0.10 1,2% 10.20 19.66 1.20 0.47 0.74 0.78 0.24 0.69 0.81 1.39 1.19 0.83 0.46 0.66 0.31 0.10 The feed was provided with semi-ad libitum and free-drinking water Pigs were weighed at the beginning and at days, 14 days, 21 days and the end of the experiment at 28 days to calculate the daily weight (ADG) by the week and by the entire experiment period Feed was weighed daily to calculate intake (FI) and weight gain / feed (G: F) by the week of the experiment and by the entire time of the experiment At the end of the experiment, 12 pigs (male: female ratio was 1: 1) for each treatment were selected for blood sampling and analysis of plasma urea nitrogen content 2.4.3 Estimation of optimal SID SAA:Lys ratio for 10–20 kg pigs A total of 108 crossbred pigs with an average initial BW of 11,88 kg were used in the experiment They were allotted to one of six treatments on the basis of initial BW with six replicate pens per treatment and three pigs per pen (balanced mixed sex) The diets 1–5 with 1.13% SID Lys was set to be second limiting AA These diets contained five graded levels of SID SAA: Lys ratios (50%, 55%, 60%, 65%, and 70%) by supplementing graded levels of DL ‐Met Diet was formulated to be adequate in all AA (1.25% SID Lys) (table 2.5) The diet formulation was followed by the approach published by Warnants et al (2003) To avoid imbalances amongst amino acids with the increases of dietary SID Met+Cys, there were small changes in the ratios of corn and soya bean meal and some crystalline amino acids of the last diet The experimental diets were formulated based on corn, broken rice, soya bean meal, full-fat soy and soy protein concentrate using analysed ingredient AA contents and published SID coefficients to meet or exceed minimum amino acids requirement (‘AMINODat 5.0 Platinum’ 2016; NRC 2012) Net energy (NE) in diets is the same in level 10,3 MJ/kg in all diets Table 2.5 Ingredient composition of experimental diets of optimal SID SAA:Lys ratio for 10–20 kg pigs (as-fed) Feed ingredients (%) Corn Broken rice Soya bean meal Full fat soya Soy protein concentrate Whey powder Corn starch DCP 19% Limestone Mineral‐vitamin premix * Salt DL-Methionine L-Threonine L-Tryptophan L-Valine L-Lysine HCl Total Trial 29.69 27.67 15.00 3.06 15.76 5.00 1.00 1.50 0.44 0.30 0.51 0.00 0.03 0.01 0.00 0.03 100 Trial 29.69 27.67 15.00 3.06 15.76 5.00 1.00 1.50 0.44 0.30 0.51 0.058 0.03 0.01 0.00 0.03 100 Trial 29.69 27.67 15.00 3.06 15.76 5.00 1.00 1.50 0.44 0.30 0.51 0.116 0.03 0.01 0.00 0.03 100 Trial 29.69 27.67 15.00 3.06 15.76 5.00 1.00 1.50 0.44 0.30 0.51 0.175 0.03 0.01 0.00 0.03 100 Trial 29.69 27.67 15.00 3.06 15.76 5.00 1.00 1.50 0.44 0.30 0.51 0.233 0.03 0.01 0.00 0.03 100 Trial 34.03 25.00 15.00 11.28 5.00 5.00 0.71 1.69 0.32 0.30 0.50 0.29 0.23 0.09 0.12 0.44 100 *1 kg Pre-Starter 500 (lợn – 20kg) contains 11.000.000 IU vitamin A; 1.500.000 IU vitamin D3; 40.000 mg vitamin E; 2.000 mg vitamin K3; 2.4000 mg vitamin B1; 4.000 mg vitamin B2; 27.000 mg vitamin B3; 13.500 mg vitamin B5; 4.000 mg vitamin B6; 1.700 mg vitamin B9; 35.000 mcg vitamin B12; 140.000 mcg biotin, 31.000 mg Fe; 20.000 mg Cu; 92.500 mg Zn; 40.000 mg Mn; 400 mg I; 420 mg Co; 225 mg Se; 120.000 mcg Cr Table 2.6 Nutrient composition of experimental diets of optimal SID SAA:Lys ratio for 10–20 kg pigs (% DM) Nutrient composition, % NE (MJ/kg) CP, % SID Lys, % SID Met, % SID M+C, % SID Thr, % SID Trp, % SID Ile, % SID Val, % SID Leu, % SID Arg, % SID Phe, % SID His, % Calcium, % Avail P, % Sodium, % Ratio to SID Lys, % SID Met, % SID M+C, % SID Thr, % SID Trp, % SID Ile, % SID Val, % SID Leu, % SID Arg, % SID, Phe, % SID His, % 50 10.5 23.04 1.13 0.29 0.56 0.73 0.25 0.83 0.90 1.53 1.45 0.97 0.52 0.70 0.35 0.25 55 10.5 23.04 1.13 0.34 0.62 0.73 0.25 0.83 0.90 1.53 1.45 0.97 0.52 0.70 0.35 0.25 SID SAA:Lys, % 60 65 10.5 10.5 23.04 23.04 1.13 1.13 0.39 0.44 0.68 0.73 0.73 0.73 0.25 0.25 0.83 0.83 0.90 0.90 1.53 1.53 1.45 1.45 0.97 0.97 0.52 0.52 0.70 0.70 0.35 0.35 0.25 0.25 0.26 0.50 0.65 0.22 0.73 0.80 1.35 1.28 0.86 0.46 0.30 0.55 0.65 0.22 0.73 0.80 1.35 1.28 0.86 0.46 0.35 0.60 0.65 0.22 0.73 0.80 1.35 1.28 0.86 0.46 0.39 0.65 0.65 0.22 0.73 0.80 1.35 1.28 0.86 0.46 70 10.5 23.04 1.13 0.49 0.79 0.73 0.25 0.83 0.90 1.53 1.45 0.97 0.52 0.70 0.35 0.25 62 10.5 24.82 1.25 0.48 0.77 0.81 0.28 0.89 0.95 1.36 1.22 1.03 0.55 0.70 0.35 0.25 0.43 0.70 0.65 0.22 0.73 0.80 1.35 1.28 0.86 0.46 0.38 0.62 0.65 0.22 0.71 0.76 09 0.98 0.82 0.44 The feed was provided with semi-ad libitum and free-drinking water Pigs were weighed at the beginning and at days, 14 days and the end of the experiment at 21 days to calculate the daily weight (ADG) by the week and by the entire experiment period Feed was weighed daily to calculate intake (FI) and weight gain / feed (G: F) by the week of the experiment and by the entire time of the experiment At the end of the experiment, 12 pigs (male: female ratio was 1: 1) for each treatment were selected for blood sampling and analysis of plasma urea nitrogen content 2.4.4 Estimation of optimal SID SAA:Lys ratio for 30–50 kg pigs A total of 72 crossbred pigs with an average initial BW of 32.9 kg were used in the experiment They were allotted to one of six treatments on the basis of initial BW with six replicate pens per treatment and two pigs (one barrow and one gilt) per pen The diets 1–5 with 1.0% SID Lys was set to be second limiting amino acid These diets contained five graded levels of SID SAA: Lys ratios (50%, 10 55%, 60%, 65%, and 70%) by supplementing graded levels of DL‐Met Diet was formulated to be adequate in all AA (1.11% SID Lys) (table 2.7) The diet formulation was followed by the approach published by Warnants et al (2003) To avoid imbalances amongst amino acids with the increases of dietary SID Met+Cys, there were small changes in the ratios of corn and soya bean meal and some crystalline amino acids of the last diet The experimental diets were formulated based on corn, soya bean meal and rice bran using analysed ingredient AA contents and published SID coefficients to meet or exceed minimum amino acids requirement (‘AMINODat 5.0 Platinum’ 2016; NRC 2012) Net energy (NE) in diets is the same in level 10,3 MJ/kg in all diets Table 2.7 Ingredient composition of experimental diets of optimal SID SAA:Lys ratio for 30–50 kg pigs (as-fed) Feed ingredients (%) 50 57.08 12.00 26.64 0.23 1.00 1.51 0.54 0.30 0.44 0.00 0.08 0.02 0.16 0.00 100 Corn Rice bran Soya bean meal Palm oil Corn starch DCP 19% Limestone Vitamin mineral premix* Salt DL Methionine L-Threonine L-Tryptophan L-Lysine HCl L-Valine Total 55 57.08 12.00 26.64 0.23 0.95 1.51 0.54 0.30 0.44 0.00 0.08 0.02 0.16 0.00 100 SID SAA to Lys, % 60 65 57.08 57.08 12.00 12.00 26.64 26.64 0.23 0.23 0.90 0.85 1.51 1.51 0.54 0.54 0.30 0.30 0.44 0.44 0.00 0.00 0.08 0.08 0.02 0.02 0.16 0.16 0.00 0.00 100 100 70 57.08 12.00 26.64 0.23 0.80 1.51 0.54 0.30 0.44 0.00 0.08 0.02 0.16 0.00 100 64 58,87 12.00 25.52 0.00 0.00 1.51 0.55 0.30 0.44 0.22 0.17 0.04 0.34 0.04 100 *1 kg Pre-Starter 500 (20 – 40kg) contains 9.000.000 IU vitamin A; 1.300.000 IU vitamin D3; 33.000 mg vitamin E; 2.000 mg vitamin K3; 2.4000 mg vitamin B1; 3.000 mg vitamin B2; 25.000 mg vitamin B3; 12.000 mg vitamin B5; 3.300 mg vitamin B6; 1.500 mg vitamin B9; 35.000 mcg vitamin B12; 125.000 mcg biotin, 31.000 mg Fe; 30.000 mg Cu; 92.500 mg Zn; 31.000 mg Mn; 460 mg I; 420 mg Co; 180 mg Se; 120.000 mcg Cr Table 2.8 Nutrient composition of experimental diets of optimal SID SAA:Lys ratio for 30–50 kg pigs (% DM) Nutrient composition, % NE (MJ/kg) CP, % SID Lys, % SID Met, % SID M+C, % SID Thr, % SID Trp, % SID Ile, % SID Val, % SID Leu, % 50 10.25 19.00 1.00 0.25 0.50 0.67 0.21 0.68 0.76 1.40 55 10.25 19.00 1.00 0.30 0.55 0.67 0.21 0.68 0.76 1.40 SID SAA:Lys, % 60 65 10.25 10.25 19.00 19.00 1.00 1.00 0.35 0.40 0.60 0.65 0.67 0.67 0.21 0.21 0.68 0.68 0.76 0.76 1.40 1.40 11 70 10.25 19.00 1.00 0.45 0.70 0.67 0.21 0.68 0.76 1.40 64 10.25 19.00 1.11 0.47 0.71 0.74 0.23 0.66 0.78 1.38 SID Arg, % SID Phe, % SID His, % Calcium, % Avail P, % Sodium, % Ratio to SID Lys, % SID Met, % SID M+C, % SID Thr, % SID Trp, % SID Ile, % SID Val, % SID Leu, % SID Arg, % SID, Phe, % SID His, % 1.16 0.81 0.44 0.70 0.31 0.19 1.16 0.81 0.44 0.70 0.31 0.19 1.16 0.81 0.44 0.70 0.31 0.19 1.16 0.81 0.44 0.70 0.31 0.19 1.16 0.81 0.44 0.70 0.31 0.19 1.13 0.79 0.43 0.70 0.31 0.19 25 50 67 21 68 76 140 116 81 44 30 55 67 21 68 76 140 116 81 44 35 60 67 21 68 76 140 116 81 44 40 65 67 21 68 76 140 116 81 44 45 70 67 21 68 76 140 116 81 44 42 64 67 21 59 70 124 102 71 39 The feed was provided with semi-ad libitum and free-drinking water Pigs were weighed at the beginning and at days, 14 days and the end of the experiment at 21 days to calculate the daily weight (ADG) by the week and by the entire experiment period Feed was weighed daily to calculate intake (FI) and weight gain / feed (G: F) by the week of the experiment and by the entire time of the experiment At the end of the experiment, 12 pigs (male: female ratio was 1: 1) for each treatment were selected for blood sampling and analysis of plasma urea nitrogen content 2.5 Statistical analysis All data were analysed by ANOVA using the GLM procedure (SAS Inst Inc., Cary, NC) with initial BW (covariate) and dietary treatment as sources of variation To estimate Lys requirement, ADG and G:F (overall treatment means) data were analysed by curvilinear‐plateau models For the PUN data were analysed by linear broken‐line models (Robbins et al., 2006) CHAPTER 3: RESULTS AND DISCUSSIONS 3.1 Estimation of SID Lys requirement for 10-20 kg pigs The effects of increasing SID Lys on growth performance and PUN concentration of 10-20 kg pigs were represented in table 3.1 The final body weight of pigs was significantly different between experiments (P0.01) The FCR was improved with the linear increase (P