Modeling the effects of standardized ileal digestible isoleucine to lysine ratio on growth performance of nursery pigs. Transl Anim Sci 2017;1:437-447. [PMID: 32704667 PMCID: PMC7204974 DOI: 10.2527/tas2017.0048]

An Estimation of the Requirements of the Standardized Ileal Digestible Tryptophan, Valine, Isoleucine and Methionine on Young Pigs' (Up to 50 kg) Feed Efficiency: A Meta-Regression Analysis

Currently, the NRC amino acid (AA) requirements for pigs published in 2012 are used as a reference in variable swine industries. However, recent results in several articles suggest that the standardized ileal digestible (SID) AA-lysine (Lys) ratio significantly evolved over the last two decades, while some publications report inconsistent outcomes. Therefore, the present study used a meta-regression analysis to assess the relative ratio to lysine to maximize the feed efficiency of four essential amino acids (tryptophan, valine, isoleucine, and methionine) in pig diets. According to the PRISMA guidelines, articles examining the target AA requirement using a basal diet supplemented with varying levels of crystalline AA (tryptophan, valine, isoleucine, or methionine) were identified across Scopus, PubMed, and Science Direct. As a result, 23, 22, 16, and 9 articles using tryptophan, valine, isoleucine, and methionine were selected and categorized into experiments for inclusion in our meta-analysis. The results suggested that the requirements of tryptophan, valine, isoleucine, and methionine in our meta-regression analysis were superior to NRC recommendations, regardless of the regression models and the growth phases with significant RSQ values (RSQ ≈ 1). Also, the QUAD and CLP regression models emphasized higher requirements than the LP model for the great majority of amino acids and growth phases. The results of the QUAD and CLP models were selected as estimations of the amino acid requirements for pigs under challenged conditions, whereas the LP model was chosen to estimate the amino acid requirements of genetically improved pigs under a modern housing system. The results of this meta-regression analysis could be used to refresh the information on the NRC amino acids (AA) requirements for swine.

Growth performance, serum parameters, inflammatory responses, intestinal morphology and microbiota of weaned piglets fed 18% crude protein diets with different ratios of standardized ileal digestible isoleucine to lysine

The present study was to explore the Ile requirement of piglets fed 18% crude protein (CP) diets. Two hundred and fifty 28-day-old Duroc × Landrace × Yorkshire piglets (8.37 ± 1.92 kg) were randomly divided into 5 dietary treatments (10 piglets per replicate, 5 barrows and 5 gilts per replicate) with 45%, 50%, 55%, 60%, 65% standardized ileal digestible (SID) Ile-to-Lys ratios, and the SID Lys was formulated to 1.19%. The experimental design consisted of two phases (d 1 to 14 and d 15 to 28). Results showed that average daily gain (ADG) had a tendency to quadratically increase as the SID Ile-to-Lys ratio increased (P = 0.09), and the optimum SID Ile-to-Lys ratios required to maximize ADG were 48.33% and 54.63% for broken-line linear model and quadratic polynomial model, respectively. Different SID Ile-to-Lys ratios had no significant effects on average daily feed intake and gain-to-feed ratio. Dry matter (P < 0.01), CP (P = 0.01), ether extract (P = 0.04), gross energy (P < 0.01) and organic matter (P < 0.01) digestibility increased quadratically. Serum total cholesterol levels decreased linearly (P = 0.01) and quadratically (P < 0.01); aspartate aminotransferase (P < 0.01), interleukin-1β (P = 0.01), and tumor necrosis factor-α (P < 0.01) levels decreased quadratically; immunoglobulin G (P = 0.03) and immunoglobulin M (P = 0.01) concentrations increased quadratically. Serum Ser levels decreased linearly (P < 0.01) and quadratically (P = 0.01); Glu (P = 0.02), Arg (P = 0.05), and Thr (P = 0.03) levels decreased quadratically; Gly (P < 0.01) and Leu (P = 0.01) levels decreased linearly; Ile (P < 0.01) concentration increased linearly. Duodenal villus height (P < 0.01) and villus height to crypt depth ratio (P < 0.01) increased quadratically. The deficiency or excess of Ile decreased short chain fatty acid-producing bacteria abundance and increased pathogenic bacteria abundance. Overall, taking ADG as the effect index, the optimum SID Ile-to-Lys ratios of piglets offered 18% CP diets were 48.33% and 54.63% based on two different statistical models, respectively, and the deficiency or excess of lle negatively affected piglet growth rates and health status.

Effects of high-protein distillers dried grains on growth performance of nursery pigs

A total of 300 pigs (DNA 400 × 200, Columbus, NE), initially 11.1 kg, were used in a study to evaluate the effects of increasing amounts of high-protein distillers dried grains (HP DDG) on growth performance and to estimate its energy value relative to corn. Pigs were weaned, placed in pens with five pigs each, and fed a common diet for 21 d after weaning. Then, pens were assigned to treatments in a randomized complete block design. There were 5 treatments with 12 replicates per treatment. Treatments consisted of 0, 10, 20, 30, or 40% HP DDG, formulated by changing only the amounts of corn and feed-grade amino acids. Pigs were weighed weekly for 21 d to evaluate average daily gain (ADG), average daily feed intake (ADFI), and gain-to-feed ratio (G:F). Caloric efficiency was obtained by multiplying ADFI by kcal of net energy (NE) per kg of diet and dividing by ADG. The NE values for corn and soybean meal were obtained from NRC (2012), and initial estimates for HP DDG NE were derived from the Noblet et al. (1994) equation. The energy of HP DDG was estimated based on caloric efficiency relative to the diet without HP DDG. Pigs fed diets with increasing HP DDG had a linear decrease (P < 0.01) in ADG, ADFI, and final body weight. There was a tendency for a quadratic response (P = 0.051) in G:F, with the greatest G:F observed for pigs fed diets with 40% HP DDG. There was a linear reduction (P < 0.05) in caloric efficiency with increasing amounts of HP DDG, indicating the initial NE estimate of HP DDG was underestimated. The use of caloric efficiency to estimate the energy value of HP DDG presents several limitations. This approach assumes that the NE values of corn and soybean meal are accurate and does not take into account possible changes in body composition, which can influence the G:F response as leaner pigs are more efficient. In conclusion, increasing HP DDG in the diet linearly decreased ADG and ADFI. Using caloric efficiency to estimate energy content relative to corn, the HP DDG used in this study was estimated to be 97.3% of the energy value of corn. Direct or indirect calorimetry is needed to confirm this value.

Effects of soybean meal level on growth performance of 11- to 25-kg nursery pigs

Four experiments were conducted to determine the effects of increasing soybean meal (SBM) level in diets with or without 25% distillers dried grains with solubles (DDGS) on growth performance of nursery pigs raised in university or commercial facilities. Treatments were arranged in a 2 × 3 factorial with main effects of SBM (27.5%, 32.5%, or 37.5% of the diet) and DDGS (0% or 25% of the diet). A total of 296, 2,502, 4,118, and 711 pigs with initial body weight (BW) of 10.6, 11.7, 12.5, and 12.3 kg were used in Exp. 1, 2, 3, and 4, respectively. There were 10, 16, 13, and 12 replicates per treatment in Exp. 1, 2, 3, and 4, respectively. After weaning, pigs were fed common diets for approximately 21 d. Then, pens of pigs were assigned to treatments in a randomized complete block design with BW as the blocking factor and experimental diets were fed for 21 d. Pigs were weighed and feed disappearance measured to calculate average daily gain (ADG), average daily feed intake (ADFI), gain-to-feed ratio (G:F), and caloric efficiency (CE). Data were analyzed using the GLIMMIX procedure of SAS with block as a random effect and treatment as a fixed effect. Single degree-of-freedom contrasts were constructed to test the linear and quadratic effects of increasing SBM and their interactions with DDGS. Pigs used in all experiments did not undergo major health challenges during the experimental period and due to the low number of mortality and cull events, statistical analysis was not performed on these variables. The average cull rate was 0.7%, 0.5%, 0.2%, and 0%, and the mortality rate was 0.7%, 0.3%, 0.4%, and 0% in Exp. 1–4, respectively. There were interactions (P ≤ 0.039) between SBM and DDGS for G:F and CE in Exp. 2 and for ADG and ADFI in Exp. 3. These were mostly driven by increasing SBM negatively affecting performance in a greater magnitude when diets contained DDGS compared to diets without DDGS. The main effects of DDGS and SBM were more consistently observed across experiments. Pigs fed diets with 25% DDGS had decreased (P ≤ 0.001) ADG and ADFI in all experiments, as well as poorer (P ≤ 0.028) G:F and CE except for Exp. 3. Feeding increasing amounts of SBM generally did not result in any major impact in ADG but consistently improved (linear, P ≤ 0.078) G:F and CE across experiments.

Effects of amino acid biomass or feed-grade amino acids on growth performance of growing swine and poultry

Three experiments were conducted to determine the effect of three fermented amino acids (AA) with their respective biomass compared to crystalline AA on the growth performance of swine and poultry. In experiment 1, 315 barrows (DNA 200 × 400, initially 11.3 ± 0.69 kg) were allotted to 1 of 4 dietary treatments with 5 pigs per pen and 15 or 16 pens per treatment. Dietary treatments included a negative control (16% standardized ileal digestible [SID] Tryptophan:lysine [Trp:Lys] ratio), positive control (21% SID Trp:Lys ratio from crystalline Trp), or diets containing Trp with biomass to provide 21 or 23.5% SID Trp:Lys ratios, respectively. Pigs fed the positive control or low Trp with biomass diet had increased (P < 0.05) ADG compared to pigs fed the negative control diet, with pigs fed the high Trp with biomass diet intermediate. Pigs fed the low Trp with biomass diet had increased (P < 0.05) G:F compared to the negative control diet, with others intermediate. In experiment 2, 1,320 1-d-old male broilers (Cobb 500, initially 45.2 g) were allotted to one of four dietary treatments with 33 birds per pen and 10 pens per treatment. Dietary treatments included a negative control (58/58% Threonine:lysine [Thr:Lys] ratio), positive control (65/66% Thr:Lys ratio from crystalline Thr), or diets containing Thr with biomass to provide 65/66 or 69/70% Thr:Lys ratios in starter and grower diets, respectively. Broilers fed the positive control or Thr with biomass diets had increased (P < 0.05) ADG compared to broilers fed the negative control diet. Broilers fed the positive control or the low Thr with biomass diet had increased (P < 0.05) G:F compared to the negative control and high Thr with biomass treatments. In experiment 3, 2,100 one-day-old male broilers (Cobb 500, initially 39.4 g) were allotted to one of four dietary treatments with 35 birds per pen and 15 pens per treatment. Dietary treatments included a negative control (59/63% Valine:lysine [Val:Lys] ratio), positive control (75/76% Val:Lys ratio from crystalline Val), or diets containing Val with biomass to provide 75/76 or 84/83% Val:Lys ratios in starter and grower diets, respectively. Broilers fed the positive control or Val with biomass diets had increased (P < 0.05) ADG, ADFI, and G:F compared to those fed the negative control diet. In conclusion, Trp, Thr, or Val with their respective biomass appear to be equally bioavailable and a suitable alternative to crystalline AA in swine and poultry diets.

Effects of standardized ileal digestible histidine to lysine ratio on growth performance of 7- to 11-kg nursery pigs

Histidine may be the sixth limiting amino acid (AA) in practical nursery diets supplemented with high amounts of feed-grade AA. Therefore, 2 experiments were conducted to determine the standardized ileal digestible (SID) His:Lys ratio requirement estimate for growth performance of 7- to 11-kg nursery pigs. A total of 360 and 350 pigs (DNA 241 × 600, Columbus, NE; initially 7.1 ± 0.31 and 6.6 ± 0.36 kg) were used in Exp. 1 and 2, respectively. There were 5 pigs per pen with 12 replicates per treatment in Exp. 1 and 10 replicates per treatment in Exp. 2. After weaning, pigs were fed a common pelleted diet for 10 d in Exp. 1 and 7 d in Exp. 2. Then, pens were assigned to treatments in a randomized complete block design with body weight (BW) as the blocking factor. Dietary treatments consisted of SID His:Lys ratios of 24%, 28%, 32%, 36%, 40%, and 44% in Exp. 1 and 24%, 28%, 30%, 32%, 34%, 36%, and 42% in Exp. 2. Experimental diets were fed in pellet form for 10 or 14 d in Exp. 1 and 2, followed by a common mash diet for 15 or 14 d, respectively. Data were analyzed using the GLIMMIX and NLMIXED procedures of SAS, fitting data with heterogeneous variance when needed. The competing statistical models utilized were quadratic polynomial, broken-line linear (BLL), and broken-line quadratic. In Exp. 1, increasing SID His:Lys ratio increased (quadratic, P = 0.001) ADG, ADFI, G:F, and day 10 BW. In Exp. 2, ADG, G:F, and day 14 BW increased (quadratic, P = 0.001), and ADFI increased linearly (P = 0.001) with increasing SID His:Lys ratio. The best-fitting model for all response variables analyzed was the BLL. In Exp. 1, requirement estimates were 29.7%, 29.1%, and 29.8% SID His:Lys ratio for ADG, ADFI, and G:F, respectively. In Exp. 2, the SID His:Lys ratio requirement estimates were 31.0% for ADG and 28.6% for G:F. These results suggest that the SID His requirement estimate for growth performance is no more than 31% of Lys and that the NRC (2012) SID His requirement of 34% of Lys may be overestimated for 7- to 11-kg pigs.