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.

Improving performance of finishing pigs with added valine, isoleucine, and tryptophan: validating a meta-analysis model.

Based on results of a recent meta-analysis, we hypothesized that increased dietary Val, Ile, or Trp could correct possible amino acid interactions because of excess Leu in diets containing high levels of corn protein, namely dried distiller's grains with solubles (DDGS). A total of 1,200 pigs (PIC TR4 × (Fast LW × PIC L02); initially 33.6 ± 0.6 kg) were used in a 103-d study. The 6 dietary treatments were corn-soybean meal (SBM)-DDGS-based as follows: (1) high SBM and low level of l-Lys HCl (HSBM), (2) high l-Lys HCl and moderate Ile, Val, Trp (AA above NRC 2012 estimates; NC), (3) moderate l-Lys HCl and high Ile, Val, and Trp (PC), and PC with either increased (4) L-Val (PC+Val), (5) L-Ile (PC+Ile), or (6) L-Trp (PC+Trp). Pigs fed the NC diet were predicted to have the poorest average daily gain (ADG), the PC diet to be intermediate, and pigs fed the HSBM, PC+Val, PC+Ile, and PC+Trp have the same and highest predicted ADG. In the grower period (34 to 90 kg), ADG was greater (Ρ < 0.05) for the pigs fed HSBM and PC+Val diets than the NC with pigs fed other diets intermediate. Pigs fed HSBM were more (Ρ < 0.05) efficient (G:F) than the NC and PC with pigs fed other diets intermediate. In the finisher period (90 to 136 kg), ADG was greater (Ρ < 0.05) for pigs fed PC+Ile than that of the NC with pigs fed other diets intermediate. Pigs fed PC+Val had greater (Ρ < 0.05) average daily feed intake (ADFI) than the NC with pigs fed other diets intermediate. However, PC+Ile pigs were more (Ρ < 0.05) efficient than PC+Val with pigs fed other diets intermediate. Overall, ADG was greater (Ρ < 0.05) for pigs fed HSBM, PC+Val, and PC+Ile diets than the NC with pigs fed other diets intermediate. Pigs fed the PC+Val diet had greater (Ρ < 0.05) ADFI than the NC with pigs fed other diets intermediate. No differences were detected between treatments for overall G:F or other carcass characteristics. In conclusion, increasing Val or Ile in high l-Lys-HCl-DDGS-based diets improved growth performance compared with pigs fed diets containing high levels of l-Lys HCl without added Val and Ile. These results present evidence that the recently developed meta-analysis can predict the relative differences in overall ADG for pigs fed the NC, PC, PC+Val, and PC+Ile diets; however, the predicted G:F was less accurate. The data demonstrate that the negative effects of high Leu concentrations in corn-DDGS-based diets can be reversed by increasing the ratios of Val and Ile relative to Lys.

Estimate of the energy value of soybean meal relative to corn based on growth performance of nursery pigs.

BACKGROUND: Two experiments were conducted to determine the effects of increasing amounts of soybean meal (SBM) in swine diets and estimate the energy value of SBM. METHODS: A total of 2233 pigs (PIC 337 × 1050, Hendersonville, TN) and 3796 pigs (PIC 359 × C40), initially 11.0 kg and 17.6 kg body weight (BW), were used in Exp. 1 and 2, respectively. In Exp. 1, pigs were placed in 92 pens each containing 20 to 27 pigs. In Exp. 2, pigs were placed in 84 pens each containing 37 to 43 pigs. Treatments were assigned in a randomized complete block design with BW as the blocking factor. Dietary treatments consisted of 21%, 27%, 33%, or 39% SBM in Exp. 1 and 17.5%, 22%, 26.5%, 31%, 35.5%, or 40% SBM in Exp. 2, obtained by changing the inclusion rate of feed-grade amino acids and corn grain. For Exp. 1, representative samples of corn grain, SBM, and distillers dried grains with solubles were analyzed for total AA content prior to diet formulation. For Exp. 2, diets were formulated using NRC (2012) nutrient loadings. Treatment diets were fed for 21 and 22 d (Exp. 1 and 2) and there were 23 replicates in Exp. 1 and 14 replicates in Exp. 2. Pigs were weighed and feed disappearance measured weekly to calculate average daily gain (ADG), average daily feed intake (ADFI), gain-to-feed ratio (G:F), and caloric efficiency (CE). Data were analyzed with block as a random effect and treatment as a fixed effect, and contrasts were constructed to test the linear and quadratic effects of increasing SBM. RESULTS: In Exp. 1, there was a tendency (linear, P = 0.092) for a decrease in ADFI as SBM increased. There was a tendency (P = 0.090) for a quadratic response for ADG, with a decrease in ADG observed with 39% SBM inclusion. Pigs fed diets with increasing SBM had a tendency (quadratic, P = 0.069) for an increase in G:F up to 33% SBM and an improvement (linear, P = 0.001; quadratic, P = 0.063) in CE with increasing SBM. Using CE to estimate the energy of SBM relative to corn, a value of 105.4% of corn energy or 2816 kcal/kg NE was determined using all data points. When removing the CE value of the 39% SBM treatment due to the quadratic tendency, SBM was estimated to have 121.1% of corn energy or 3236 kcal/kg NE. In Exp. 2, there was a decrease (linear, P = 0.001) in ADFI. Pigs fed increasing SBM had a tendency (linear, P = 0.065) for reduced ADG but an improvement (linear, P = 0.001) in G:F and CE as SBM increased. The energy value of SBM was estimated as 124.7% of corn energy or 3332 kcal/kg NE. CONCLUSIONS: The results suggest that feeding increasing levels of SBM improves G:F and CE. The energy value of SBM was estimated to be between 105% and 125% of corn, which is much greater than the NRC (2012) would indicate.

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.

Meta-regression analysis to predict the influence of branched-chain and large neutral amino acids on growth performance of pigs1.

A meta-analysis was conducted to evaluate the effects of branched-chain amino acids (BCAA), their interactions, and interactions with large neutral amino acids (LNAA) to develop prediction equations for growth performance of pigs. Data from 25 papers, published from 1995 to 2018, for a total of 44 trials and 210 observations were recorded in a database. Diets were reformulated using the NRC (2012) loading values to estimate nutrient concentrations. The response variables were average daily gain (ADG), average daily feed intake (ADFI), and gain-to-feed ratio (G:F). The predictor variables tested included average body weight (BW), crude protein, neutral detergent fiber, Ile:Lys, Leu:Lys, Val:Lys, BCAA:Lys, Ile:Leu, Val:Leu, Ile:Val, (Ile+Val):Leu, Trp:Lys, Leu:Trp, Ile:Trp, Val:Trp, BCAA:Trp, Met:Lys, Leu:Met, Ile:Met, Val:Met, BCAA:Met, His:Lys, Leu:His, Ile:His, Val:His, BCAA:His, Thr:Lys, Leu:Thr, Ile:Thr, Val:Thr, BCAA:Thr, (Phe+Tyr):Lys, Leu:(Phe+Tyr), Ile:(Phe+Tyr), Val:(Phe+Tyr), BCAA:(Phe+Tyr), LNAA:Lys, Leu:LNAA, Ile:LNAA, Val:LNAA, and BCAA:LNAA. Amino acids were expressed on standardized ileal digestible basis. The MIXED procedure of SAS (SAS Institute Inc., Cary, NC) was used to develop the equations. The inverse of squared SEM was used to account for heterogeneous errors using the WEIGHT statement. Models were selected with a step-wise manual forward selection. In order to be included in the final model, predictor variables had to be statistically significant (P < 0.05) and provide an improvement of at least 2 points in Bayesian information criterion. The optimum equations were: ADG, g = - 985.94 + (15.2499 × average BW (kg)) - (0.08885 × average BW × average BW) + (1.063 × Leu:Lys) + (20.2659 × Ile:Lys) - (0.1479 × Ile:Lys × Ile:Lys) + (9.2243 × (Ile+Val):Leu) - (0.03321 × (Ile+Val):Leu × (Ile+Val):Leu) - (0.4413 × Ile:Trp); G:F, g/kg = 648.3 - (6.2974 × average BW (kg)) + (0.02051 × average BW × average BW) + (0.5396 × Ile:Lys) + (1.7284 × Val:Lys) - (0.00795 × Val:Lys × Val:Lys) - (1.7594 × Met:Lys); and ADFI, kg = predicted ADG/predicted G:F. Overall, the prediction equations suggest that increasing Leu:Lys negatively impacts ADG due to a reduction in G:F and ADFI caused by insufficient levels of other BCAA and LNAA relative to Leu. According to the model, the addition of Val, Ile, and Trp, alone or in combination, has the potential to counteract the negative effects of high dietary Leu concentrations on growth performance.

Effects of increasing dietary zinc on growth performance and carcass characteristics of pigs raised under commercial conditions.

A total of 2,430 pigs (PIC 337 × 1050; Hendersonville, TN; initially 30.1 kg) were used in a 113-d growth trial to determine the effects of increasing dietary Zn on growth performance and carcass characteristics of finishing pigs raised under commercial conditions. Pens of pigs were assigned to be fed one of five dietary treatments in a randomized complete block design. Treatments consisted of 50, 87.5, 125, 162.5, or 200 mg/kg added Zn from Zn hydroxychloride (IntelliBond Z, Micronutrients, Indianapolis, IN). Two identical barns were used for a total of 18 pens per treatment with 27 pigs per pen. Experimental diets were fed in five phases and contained a vitamin-trace mineral premix without added Zn. Pens of pigs were weighed approximately every 2 wk to calculate average daily gain (ADG), average daily feed intake (ADFI), and gain-to-feed ratio (G:F). At the end of the experimental period, pigs were tattooed with a pen identification number and transported to a packing plant to measure hot carcass weight (HCW), backfat, loin depth, and calculated lean percentage. Data were analyzed block nested within barn as a random effect and pen as the experimental unit. From days 0 to 42, pigs fed diets with increasing added Zn had lower (linear, P = 0.043) ADFI and a tendency (P = 0.092) for lower ADG. From days 42 to 113, increasing added Zn resulted in a quadratic response (P = 0.042) for ADFI and a tendency (linear, P = 0.056) for improved G:F. Overall (days 0 to 113), there were tendencies for quadratic responses for ADFI (P = 0.073) and G:F (P = 0.059), with the greatest G:F observed when 125 mg/kg of Zn was fed. Increasing added Zn resulted in a linear increase (P < 0.001) in daily Zn intake. There were no differences (P > 0.10) in overall ADG, final body weight, HCW, backfat, loin depth, lean percentage, mortality, and removal rate. In conclusion, there were no improvements in ADG when feeding beyond 50 mg/kg added Zn; however, providing 125 mg/kg added Zn resulted in the greatest G:F.

Effects of zinc source and level on growth performance and carcass characteristics of finishing pigs.

An experiment was conducted to determine the effects of added Zn source and level on growth performance and carcass characteristics of finishing pigs. A total of 1,980 pigs divided into 2 groups [group 1: 1,008 pigs, TR4 × (Fast Large White × PIC L02) and group 2: 972 pigs, PIC 337 × 1,050], initially 33.3 kg, were used in a 103- or 114-d growth trial in groups 1 and 2, respectively. Treatments were arranged in a 2 × 3 factorial with 2 sources of added Zn, Zn hydroxychloride (ZnHyd; IntelliBond Z, Micronutrients, Indianapolis, IN) or Zn sulfate (ZnSO4), and 3 levels of added Zn (50, 100, or 150 mg/kg). Diets contained a vitamin-trace mineral premix without added Zn and provided 76 and 162 mg/kg Fe and Cu, respectively. All diets contained 750 FTU/kg phytase. There was a total of 14 replicates per treatment. Pens of pigs were weighed approximately every 2 wk to determine average daily gain (ADG), average daily feed intake, and gain-to-feed ratio. At the end of the experiment, pigs were transported to a packing plant to determine hot carcass weight (HCW), backfat depth, loin depth, and lean percentage. Overall, there was no evidence (P > 0.10) for interactive effects of added Zn source and level for growth performance and carcass characteristics. Pigs fed diets with increasing added Zn had a tendency (P = 0.093) for a quadratic response in ADG, with the greatest ADG observed at 100 mg/kg added Zn. There was a linear improvement (P = 0.010) in carcass yield and a quadratic response (P = 0.045) in HCW, with pigs fed 100 mg/kg added Zn having the highest HCW. Pigs fed diets with ZnHyd had improved (P = 0.017) carcass yield and a tendency (P = 0.058) for greater HCW compared with pigs fed ZnSO4. In summary, under the commercial conditions of the study and with diets containing 750 FTU/kg phytase, there were relatively small improvements in ADG of growing-finishing pigs fed added Zn beyond 50 mg/kg. Providing higher levels of added Zn improved carcass characteristics. Zinc source did not influence growth performance, but ZnHyd improved carcass characteristics compared with ZnSO4.

Branched-chain amino acid interactions in growing pig diets.

The branched-chain amino acids (BCAA) Leu, Ile, and Val share the first steps of their catabolism due to similarities in their structure. The BCAA are reversibly transaminated in skeletal muscle through the activity of branched-chain aminotransferase and then transported to the liver. They undergo an irreversible decarboxylation catalyzed by the branched-chain α-keto acid dehydrogenase complex. Both enzymes are common to Leu, Ile, and Val and increased enzymatic activity stimulated by an excess of one of them will increase the catabolism of all BCAA, which can result in antagonisms. Leucine and its keto acid are the most potent stimulators of BCAA catabolic enzymes. Moreover, BCAA and large neutral amino acids (LNAA) share common brain transporters. Research has shown that high concentrations of BCAA, especially Leu, can decrease the absorption of LNAA, such as Trp, which is a precursor of serotonin and can have a significant impact in feed intake regulation. Finally, high Leu concentrations have the ability to overstimulate the mTOR signaling pathway, resulting in an inhibitory effect on feed intake. Most of the research conducted to evaluate the impact of BCAA on growth performance of pigs seems to agree that high levels of Leu decrease weight gain, mostly due to a reduction in feed intake. However, some studies, mostly with finishing pigs, observed no evidence for an impact on growth performance even with extremely high levels of Leu. It could be hypothesized that these inconsistencies are driven by the entire dietary amino acid profile as opposed to only considering the level of Leu. Grow-finish diets typically contain high levels of Leu, but the other BCAA are also well above the requirement and could potentially mitigate the negative impact of Leu on BCAA catabolism. Indeed, some studies suggest that when diets contain high levels of Leu, more Ile and Val are needed to optimize growth performance. However, the precise relationship between BCAA and their balance in swine diets is not fully understood. More research is needed to understand and quantify the relationship between LNAA and BCAA.

Diet formulation method influences the response to increasing net energy in finishing pigs.

An experiment was conducted to compare the effects of increasing dietary net energy (NE) in finishing pig diets while either maintaining a standardized ileal digestible lysine:NE ratio (SID Lys:NE) or maintaining SID Lys as a constant percentage of the diet across increasing energy densities. A total of 150 pigs (Line 600 × 241; DNA, Columbus, NE; initially 35.7 kg) were used in a 91-d study. Pigs were blocked by sex and weight and randomly assigned to 1 of 5 treatments with 2 pigs per pen and 15 pens per treatment. Treatments included a low-energy control diet that was corn-soybean meal-based with added soybean hulls, and a 2 × 2 factorial arrangement of treatments with main effects of increasing dietary NE (medium or high by adding choice white grease) and formulation method (with a SID Lys:NE ratio or maintaining the same percentage SID Lys). Linear and quadratic contrasts were made using the control diet and the medium- and high-energy diets within each formulation method. Pigs and feeders were weighed approximately every 30 d to calculate average daily gain (ADG), average daily feed intake (ADFI), and gain-to-feed ratio (G:F). At the end of the experiment, pigs were sent to a commercial processing facility for carcass data collection. From days 0 to 34 and 34 to 61, ADG and SID Lys intake increased as NE increased (linear, P < 0.05) in pigs fed diets with a Lys:NE ratio, but not for those fed the same percentage Lys. As NE increased, NE intake and G:F increased (P < 0.01) in pigs fed diets with either formulation method. From days 61 to 91, increasing NE had no effect (P > 0.10) on ADG. There was no change in G:F in pigs fed diets with the same percentage Lys (P > 0.10), but G:F decreased then increased (quadratic, P < 0.01) in response to increasing NE in pigs fed diets with a SID Lys:NE ratio. Overall, increasing dietary NE increased (linear, P < 0.001) daily NE intake and G:F (linear, P < 0.018) with either formulation method. However, SID Lys intake, ADG, and hot carcass weight only increased (linear, P < 0.01) when a SID Lys:NE ratio was maintained. Increasing NE without maintaining a constant SID Lys:NE ratio increased backfat depth (quadratic, P = 0.01), whereas it did not in pigs fed diets with a SID Lys:NE ratio. In conclusion, increasing dietary energy density increased NE intake and G:F regardless of formulation method. However, a SID Lys:NE ratio must be maintained to achieve increased ADG and minimize fat deposition.

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.