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Four experiments were conducted to determine effects of fiber on the ideal Thr:Lys ratio for 25- to 50-kg gilts. In Exp. 1, the objective was to determine the requirement for standardized ileal digestible Lys for gilts from 25 to 50 kg BW. Seventy gilts (24.54 ± 3.28 kg BW) were used in a growth assay with 2 pigs per pen, 5 diets, and 7 replicate pens per diet. The 5 diets were based on corn and soybean meal and contained between 0.80 and 1.32% SID Lys. Results indicated that 1.09% SID Lys was needed to optimize ADG and G:F. In Exp. 2, the objective was to determine the standardized ileal digestibility of AA in corn, soybean meal, field peas, fish meal, and soybean hulls. Six ileal-cannulated gilts (26.5 ± 0.74 kg BW) were allotted to a 6 × 6 Latin square design with 6 diets and 6 periods. Values for standardized ileal digestibility of AA were calculated for all ingredients. In Exp. 3, the objective was to determine the effect of fiber on the ideal SID Thr:Lys ratio for gilts from 25 to 50 kg BW. A total of 192 gilts (26.29 ± 4.64 kg BW) were used in a growth assay with 2 pigs per pen and 8 replicate pens per treatment. Six low-fiber diets and 6 high-fiber diets were formulated using the same batches of ingredients as in Exp. 2. Within each level of fiber, diets with SID Thr:Lys ratios ranging from 45:100 to 90:100 were formulated using the SID values calculated in Exp. 2. In both types of diets, ADG and G:F linearly and quadratically (P< 0.05) increased as the Thr:Lys ratio increased. Regression analysis estimated the ideal SID Thr:Lys ratio at 0.66 and 0.63 for ADG and G:F, respectively, for pigs fed low-fiber diets and at 0.71 and 0.63, respectively, for pigs fed high-fiber diets. In Exp. 4, the objective was to determine the N balance in pigs fed low-fiber or high-fiber diets that were formulated to have SID Thr:Lys ratios of 45:100 or 60:100. The 4 diets were formulated using the same batches of ingredients as in Exp. 2, and the SID values determined in Exp. 2 were used in diet formulations. Thirty-six gilts (29.0 ± 0.74 kg BW) were individually housed in metabolism crates with 9 replicate pigs per diet. Retention of N (% of intake) was greater (P < 0.05) for pigs fed the low-fiber diets compared with pigs fed the high-fiber diets regardless of the Thr:Lys ratio. Results of these experiments indicate that increased fiber levels in diets fed to growing gilts increase the requirement for Thr and that diets with higher fiber levels should be formulated to a greater SID Thr:Lys ratio.

Three experiments were conducted to evaluate the feeding of dried distillers' grains with solubles (DDGS) in sow lactation diets. In Exp. 1, 168 multiparous sows (PIC, Camborough 22) were fed a 10% DDGS diet throughout gestation. Sows were randomly allotted to 1 of 4 corn–soybean meal lactation diets formulated to contain different levels of DDGS (0, 10, 20, and 30%, respectively). All diets were formulated to be isocaloric (3.46 Mcal ME/kg) and all other nutrients exceeded NRC (1998) nutrient recommendations. Sow ADFI was not different (P> 0.10) as DDGS level increased. Increasing DDGS resulted in a linear (P< 0.03) increase in sow weight gain (7.5, 11.3, 20.3, and 17.2 kg, respectively) and a reduction in wean-to-first-service interval (7.1, 5.2, 5.0, and 4.9 d, respectively). Increasing DDGS did not affect subsequent total born per litter (13.7, 12.8, 13.3, and 12.3, respectively; P> 0.10). In Exp. 2 and 3, lactation diets consisted of corn and 20, 30, 40, or 50% DDGS. Diets were formulated at 3.25 Mcal ME/kg, 1.05% standardized ileal digestible lysine, and all other nutrients to exceed NRC (1998) nutrient recommendations. In both experiments, sows (PIC, Camborough) were fed 40% DDGS in gestation and allocated to a randomized complete block based on the parity of the sow at the time of entry into the farrowing house. In Exp. 2, 256 gilts and multiparous sows were fed the randomly assigned diets. As DDGS inclusion increased, sow feed intake (6.2, 6.2, 6.0, and 5.9 kg/d, respectively) and sow weight gain (10.5, 10.3, 8.2, and 6.2 kg, respectively) tended to linearly decrease (P< 0.06). Sow wean to estrus differed between 20 and 30% DDGS inclusion (4.9 vs. 6.9 d; P< 0.01). Litter gain was not different (2.55, 2.53, 2.51, and 2.59 kg/d, respectively; P> 0.10) as DDGS inclusion increased. In Exp. 3, 98 multiparous sows were randomly allotted to 1 of the 4 experimental diets during the summer months. Sow feed intake, sow weight gain, and litter gain were not different (P> 0.10) between treatments. The data suggest that feeding high levels of DDGS of 40 to 50% may reduce sow feed intake and litter performance. These results demonstrate that feeding up to 30% DDGS in lactation diets can be done without adversely influencing sow or litter performance.

Two experiments were conducted to estimate the standardized ileal digestible (SID) Trp:Lys ratio requirement for growth performance of nursery pigs. Experimental diets were formulated to ensure that lysine was the second limiting AA throughout the experiments. In Exp. 1 (6 to 10 kg BW), 255 nursery pigs (PIC 327 × 1050, initially 6.3 ± 0.15 kg, mean ± SD) arranged in pens of 6 or 7 pigs were blocked by pen weight and assigned to experimental diets (7 pens/diet) consisting of SID Trp:Lys ratios of 14.7%, 16.5%, 18.4%, 20.3%, 22.1%, and 24.0% for 14 d with 1.30% SID Lys. In Exp. 2 (11 to 20 kg BW), 1,088 pigs (PIC 337 × 1050, initially 11.2 kg ± 1.35 BW, mean ± SD) arranged in pens of 24 to 27 pigs were blocked by average pig weight and assigned to experimental diets (6 pens/diet) consisting of SID Trp:Lys ratios of 14.5%, 16.5%, 18.0%, 19.5%, 21.0%, 22.5%, and 24.5% for 21 d with 30% dried distillers grains with solubles and 0.97% SID Lys. Each experiment was analyzed using general linear mixed models with heterogeneous residual variances. Competing heteroskedastic models included broken-line linear (BLL), broken-line quadratic (BLQ), and quadratic polynomial (QP). For each response, the best-fitting model was selected using Bayesian information criterion. In Exp. 1 (6 to 10 kg BW), increasing SID Trp:Lys ratio linearly increased (P <0.05) ADG and G:F. For ADG, the best-fitting model was a QP in which the maximum ADG was estimated at 23.9% (95% confidence interval [CI]: [<14.7%, >24.0%]) SID Trp:Lys ratio. For G:F, the best-fitting model was a BLL in which the maximum G:F was estimated at 20.4% (95% CI: [14.3%, 26.5%]) SID Trp:Lys. In Exp. 2 (11 to 20 kg BW), increasing SID Trp:Lys ratio increased (P <0.05) ADG and G:F in a quadratic manner. For ADG, the best-fitting model was a QP in which the maximum ADG was estimated at 21.2% (95% CI: [20.5%, 21.9%]) SID Trp:Lys. For G:F, BLL and BLQ models had comparable fit and estimated SID Trp:Lys requirements at 16.6% (95% CI: [16.0%, 17.3%]) and 17.1% (95% CI: [16.6%, 17.7%]), respectively. In conclusion, the estimated SID Trp:Lys requirement in Exp. 1 ranged from 20.4% for maximum G:F to 23.9% for maximum ADG, whereas in Exp. 2 it ranged from 16.6% for maximum G:F to 21.2% for maximum ADG. These results suggest that standard NRC (2012)recommendations may underestimate the SID Trp:Lys requirement for nursery pigs from 11 to 20 kg BW.

A depression in feed intake and growth often occurs in the weaned pig. Spray-dried plasma is often added to nursery diets in an attempt to stimulate feed intake during this lag. The current study evaluated gene expression of appetite regulators in hypothalamus and adipose tissue 4 d after weaning. Barrows (2 wk of age) were cross-fostered to a sow (SOW, n = 8) or weaned and fed a nursery diet containing either 0 or 7% spray-dried plasma (NP, n = 8, and SDP, n = 8, respectively). Piglets were allocated such that 2 size groups existed within each experimental group: small (3.5 to 4.3 kg of BW piglets) and large (4.6 to 5.7 kg of BW piglets) subsets, based on weaning weight (WW), existed within each experimental group: small (3.5 to 4.3 kg piglets) and large (4.6 to 5.7 kg piglets). Animals were killed 4 d after weaning for tissue collection. There was a weaning group × WW interactive effect (P< 0.05) on hypothalamic neuropeptide Y messenger RNA expression, such that expression was least in the small SDP piglets. No WW or weaning group effects were seen on adipose leptin, hypothalamic leptin receptor, or hypothalamic proopiomelanocortin gene expression. An effect of WW was seen on hypothalamic neuropep-tide Y, agouti-related protein, orexin, and type 2 orexin receptor gene expression, such that large pigs expressed greater amounts of these transcripts (P< 0.002). Strong positive correlations in gene expression were found among all of these genes, whose products are known to stimulate appetite. Partial correlation controlling for initial WW revealed that preweaning size explained most if not all of these associations. These data suggest that the postweaning expression of appetite-regulating genes is more dependent on preweaning conditions than on weaning diet.

Two studies were conducted to determine the effect of increasing the valine:lysine (V:L) ratio in diets of lactating sows above the minimum proposed by the NRC (1998). The first experiment involved 189 PIC, Camborough product sows (parity 1 to 4) that were allotted to 1 of 3 dietary treatments. Diets were formulated to achieve total dietary V:L ratios of 0.90, 1.05, or 1.25:1, respectively, and were corn and soybean meal-based. The second experiment involved 279 PIC, Camborough sows (parity 1 to 5) that were allotted to 1 of 4 treatments. Diets 1 and 3 were formulated using corn and a fixed inclusion of soybean meal (16.7%), with 0.27% L-lysine HCl. The V:L ratios in diets 1 and 3 were 0.73 and 1.25:1, respectively. Diets 2 and 4 were typical corn-soybean meal diets containing 0.05% L-lysine HCl, with a fixed inclusion of soybean meal (22.7%). The V:L ratios in diets 2 and 4 were 0.86 and 1.25:1, respectively. In both experiments, each litter was standardized to a minimum of 10 pigs, which achieved litter growth rates of 2.22 and 2.56 kg/d in Exp. 1 and 2, respectively. In Exp. 1, increasing the dietary V:L ratio beyond 0.90:1 did not improve (P> 0.10) the number of pigs weaned, survival rate, or piglet growth rate, even though sows were nursing more than 10 pigs per litter for 19 d. In Exp. 2, total lysine intake was similar among treatments and ranged from 52.1 to 55.3 g/d. Valine intake increased as the diet valine concentration increased (diet 1 vs. 3 and diet 2 vs. 4, P< 0.001), ranging from 40.0 to 66.1 g/d. Litter gain tended to improve (P= 0.14) when the 0.27% L-lysine HCl control (0.73 V:L) was supplemented with valine to achieve a 1.25:1 V:L ratio. In contrast, no aspect of sow or litter response was improved when the practical control diet containing 0.05% L-lysine HCl (0.86 V:L) was supplemented with valine to achieve a 1.25:1 V:L ratio. Collectively, this research shows that a V:L ratio in excess of 0.86 does not conserve maternal tissue loss or improve piglet growth rate, but a V:L ratio of 0.73 may compromise litter growth rate.

Previous research indicates that the neonatal pig does not alter feed intake in response to changes in the energy density of manufactured liquid diets. Also, the limited response of IGF-I to exogenous porcine ST (pST) previously observed in young pigs may be influenced by the source of dietary energy. Our objectives were to 1) determine the effect of a high-fat (HF; 25% fat and 4,639 kcal/kg ME; DM basis) or low-fat (LF; 2% fat and 3,481 kcal/kg ME; DM basis) manufactured liquid diet on pig performance; and 2) determine whether the limited response to exogenous pST in young pigs depends on the source of dietary energy. Two replicates of 60 pigs (n = 120; barrows and gilts distributed evenly), with an initial BW of 4,207 ± 51 g, were weaned from the sow at 10 d of age and used in a randomized complete block design. Pigs were assigned by BW to one of six pens. Diets were formulated to provide a constant lysine:ME ratio and were fed on a pen basis for a duration of 9 d. On d 5, barrows and gilts within a pen were assigned randomly to receive either 0 or 120 μg of pST•kg BW−1•d−1for 4 d. Pigs gained 336 ± 9 g/d, which resulted in an ending BW of 7,228 ± 120 g, regardless of dietary treatment (P> 0.15). Pigs fed the LF diet consumed 17% more DM per pen daily than pigs fed the HF diet (2,777 ± 67 vs. 2,376 ± 67 g/d, P< 0.01), but calculated ME intake did not differ between dietary treatments (P> 0.20). The G:F was 24% greater in HF- than in LF-fed pigs (P< 0.01). Plasma urea N concentrations were higher in the HF-fed pigs (11.0 ± 0.6 mg/dL) than in pigs fed the LF diet (6.2 ± 0.6 mg/dL; P< 0.05). Treatment with pST increased circulating IGF-I (P< 0.01) and decreased PUN (P< 0.01) concentration 32 and 25%, respectively, regardless of dietary treatment (P> 0.30). Circulating leptin averaged 1.8 ± 0.1 ng/mL and was not affected by dietary treatment (P> 0.35) or pST (P> 0.40). These results suggest that the ST/IGF axis is responsive in the young pig and the increase in circulating IGF-I and growth is independent of the source of dietary energy. Also, young pigs respond to a lower energy density liquid diet with increased feed intake, without altering growth performance, apparently utilizing a mechanism other than circulating leptin.

Two experiments were conducted to evaluate the effect of lysolecithin on performance and nutrient digestibility of nursery pigs and to determine the effects of fat encapsulation by spray drying in diets fed in either meal or pelleted form. In Exp. 1, 108 pigs (21 d of age; 5.96 ± 0.16 kg BW) were allotted to one of four dietary treatments (as-fed basis): 1) control with no added lard, 2) control with 5% added lard, 3) treatment 2 with 0.02% lysolecithin, and 4) treatment 2 with 0.1% lysolecithin in a 35-d experiment. Added lard decreased ADG (P= 0.02) and ADFI (P< 0.06) during d 15 to 35 and overall. Lysolecithin improved ADG linearly (P= 0.04) during d 15 to 35 and overall, but did not affect ADFI or G:F. Addition of lard decreased the digestibility of DM (P= 0.10) and CP (P= 0.05) and increased (P= 0.001) fat digestibility when measured on d 10. Lysolecithin at 0.02%, but not 0.10%, tended to improve the digestibility of fat (P= 0.10). On d 28, digestibilities of DM, fat, CP, P, (P= 0.001), and GE (P= 0.03) were increased with the addition of lard, and lysolecithin supplementation linearly decreased digestibilities of DM (P= 0.003), GE (P= 0.007), CP, and P (P= 0.001). In Exp. 2, 144 pigs (21 d of age, 6.04 ± 0.16 kg BW) were allotted to one of six treatments in a 3 × 2 factorial randomized complete block design. Factors included 1) level (as-fed basis) and source of fat (control diet with 1% lard; control diet with 5% additional lard; and control diet with 5% additional lard from encapsulated, spray-dried fat) and 2) diet form (pelleted or meal). Addition of lard decreased feed intake during d 0 to 14 (P= 0.04), d 15 to 35 (P= 0.01), and overall (P= 0.008), and improved G:F for d 15 to 35 (P= 0.04) and overall (P= 0.07). Encapsulated, spray-dried lard increased ADG (P= 0.004) and G:F (P= 0.003) during d 15 to 28 compared with the equivalent amount of fat as unprocessed lard. Pelleting increased ADG (P= 0.006) during d 0 to 14, decreased feed intake during d 15 to 35 (P= 0.01), and overall (P= 0.07), and increased G:F during all periods (P< 0.02). Fat digestibility was increased (P= 0.001) with supplementation of lard, and this effect was greater when diets were fed in meal form (interaction, P= 0.004). Pelleting increased the digestibility of DM, OM, and fat (P< 0.002). Results indicate that growth performance may be improved by lysolecithin supplementation to diets with added lard and by encapsulation of lard through spray drying.

A study was conducted with 20 weaned barrows (14 d, 4.98 +/- 0.21 kg) to determine the effect of feeding spray-dried plasma (SDP) after weaning on the pig's stress response to a lipopolysaccharide (LPS) challenge. After weaning, pigs were fed a diet containing 0 or 7% SDP for 7 d. On d 6 after weaning, all pigs were nonsurgically fitted with a jugular catheter. On d 7 after weaning, the pigs were given i.p. injections of either saline or LPS (150 microg/kg BW) followed by serial blood collection every 15 min for a 3-h period. Following the 3-h blood collection, all pigs were killed and tissue was collected for mRNA analysis. Pig weight on d 7 after weaning was not affected by dietary treatment (P > 0.21). Pigs fed the diet with SDP had lower (P < 0.05) levels of hypothalamic corticotropin-releasing hormone (CRH) mRNA, pituitary gland CRH receptor mRNA, and adrenal gland adrenocorticotropin-releasing hormone (ACTH) receptor mRNA. Dietary treatment did not affect pituitary gland proopiomelanocortin (POMC) mRNA. No effect of LPS treatment was observed in any of the mRNA levels examined. For both serum ACTH and cortisol, there was a significant diet x LPS treatment interaction (P < 0.01) such that both the ACTH and cortisol responses to the LPS challenge were greater in the pigs fed the diet with SDP than in the pigs fed the diet without SDP. For pigs given the saline injection, diet did not affect basal serum cortisol concentration; however, basal serum ACTH concentration was lower in those pigs fed the diet with SDP (P < 0.0001). A diet x LPS treatment interaction (P < 0.024) was observed for adrenal gland mRNA expression for steroidogenic acute regulatory (StAR) protein such that the LPS-induced increase in StAR mRNA was greater in the pigs fed SDP than in pigs fed the diet without SDP. These results demonstrate that pigs fed a diet with SDP have an increased activation of the pituitary-adrenal axis following an LPS challenge compared to pigs fed a diet without SDP.

A study was conducted with 20 weaned barrows (14 d, 4.98 +/- .21 kg) to determine the effect of spray-dried plasma (SDP) on the pig's immune response to a lipopolysaccharide (LPS) challenge. After weaning, pigs were fed a diet containing 0 or 7% SDP for 7 d. On d 6 postweaning, all pigs were fitted with a jugular catheter. On d 7 postweaning, the pigs were given an i.p. injection of either saline or LPS (150 microg/kg BW) followed by a 3-h blood collection every 15 min. Following blood collection, all pigs were killed and tissue was collected for mRNA analysis. Additionally, the small intestine was collected for measurement of villus height, crypt depth, and villus height:crypt depth ratio (VCR) at three sites (25, 50, and 75% of the total length). Feeding SDP resulted in reduced (P < 0.05) mRNA expression of tumor necrosis factor-alpha (TNF-alpha) and interleukin-1beta (IL-1beta) mRNA in the adrenal gland, spleen, hypothalamus, pituitary gland, and liver. Additionally, expression of IL-6 mRNA was reduced (P < 0.05) in the spleen and pituitary gland for pigs fed SDP. For pigs fed the diet with SDP, LPS administration did not affect (P > 0.10) cytokine mRNA expression, whereas LPS reduced expression of TNF-alpha mRNA in the spleen and IL-1beta mRNA in the adrenal gland, spleen, and thymus for pigs fed the diet without SDP. For pigs fed the diet with SDP, LPS caused serum TNF-alpha to increase 150-fold compared to a 60-fold increase for pigs fed the diet without SDP. Similarly, interferon-gamma (IFN-gamma) increased 110-fold for pigs fed the diet with SDP compared to a 16-fold increase for pigs fed the diet without SDP. For pigs fed the diet with SDP, LPS caused major villus atrophy, whereas for pigs fed the diet without SDP, LPS had no effect on intestinal morphology. These results demonstrate that the basal activation of the immune system appears to be less for pigs fed the diet with SDP compared to pigs fed the diet without SDP after weaning. Additionally, for pigs fed the diet with SDP, there appeared to be an overresponse of the immune system following LPS administration, which resulted in major damage to the mucosa of the gastrointestinal tract.

We conducted an experiment to determine the proportion of the lysine requirement of lactating sows that can be met using L-lysine × HCl. A total of 247 Pig Improvement Company (PIC) sows (parity one to four) were randomly allotted to one of five experimental diets containing .79% apparently digestible lysine. The first four diets contained 0, .075, .150, and .225% L-lysine·HCl replacing the intact lysine, primarily derived from soybean meal. Dietary crude protein was reduced from 17.9 to 16.9, 15.8, and 14.8% respectively. The fifth diet contained .174% L-lysine·HCl (15.5% CP) with added synthetic methionine, threonine, and tryptophan to restore the ratios of these amino acids to lysine to those in the control diet with no synthetic amino acids. The average lactation length was 15.7 ± .3 d. Diet did not affect ADFI, sow backfat loss, sow loin eye area loss, or weaning-to-mating interval. Sows consumed an average of 4.6 kg/d and were provided 36 g/d of digestible lysine. Replacing soybean meal with increasing levels of L-lysine·HCl did not affect sow weight change. The number of pigs weaned decreased and preweaning mortality increased linearly (P= .08) with increasing levels of L-lysine·HCl. Litters from sows fed the .174% L-lysine·HCl with added methionine, threonine, and tryptophan grew slower and had a higher mortality rate than litters from sows fed no synthetic amino acids (P< .05). The addition of synthetic methionine, threonine, and tryptophan to the .174% L-lysine·HCl diet did not improve litter growth rate, but it did increase preweaning mortality (P= .05) and decrease the number of pigs weaned (P= .06) compared to the .15% L-lysine·HCl with no additional synthetic amino acids. These additions also resulted in an increased sow weight loss (P= .10). These results suggest that when more than .075% L-lysine·HCl is used to meet the lysine requirement preweaning mortality is increased and the number of pigs weaned is decreased. Supplementation with methionine, threonine, and tryptophan failed to ameliorate the negative response associated with L-lysine·HCl, which suggests that other amino acids may be limiting.

We conducted an experiment with 289 primiparous sows to evaluate the effect of lysine intake on lactation and subsequent reproductive performance. Sows were randomly allotted to one of five experimental corn-soybean meal lactation diets. The first four diets contained incremental levels of apparently digestible lysine (.67, .86, 1.06, and 1.25%) and provided digestible lysine intakes of 27, 34, 41, and 48 g/d. All lysine was derived from intact protein sources. Synthetic valine, threonine, and methionine were used to maintain ratios to lysine that were equal to those of the .67% lysine diet. The fifth diet contained 1.06% digestible lysine and provided 43 g/d digestible lysine, but no additional synthetic amino acids were added. The average lactation length in this study was 16.9 ± .2 d. Lysine intake during lactation did not affect number of pigs weaned, litter growth rate, sow backfat loss, or weaning to mating interval. Sow weight loss and loin eye area loss decreased quadratically (P< .05) with increasing lysine intake. These were minimized at 45 and 48 g/d digestible lysine, respectively. Removing synthetic amino acids from the 1.06% digestible lysine diet resulted in an increased litter growth rate (1.98 vs 2.15 kg/d, P< .05). Increasing dietary lysine intake while maintaining amino acid ratios to lysine for valine, threonine, and total sulfur amino acids during the first lactation resulted in a linear (P< .05) decrease in second litter total born. However, removal of synthetic amino acids from the 1.06% digestible lysine diet resulted in an increased second litter total born (12.9 vs 11.2, P< .05), which tended to be higher compared with the .67% digestible lysine treatment (12.9 vs 11.7, P= .13). The results suggest that primiparous sows are able to mobilize sufficient body reserves to maintain a high level of milk production at low levels of lysine intake during a 17-d lactation. Higher levels (45 to 48 g/d) of digestible lysine are required to minimize body protein loss. The source or composition of amino acids in the lactation diet may have an effect on second litter size.

A total of 990 sows (PIC Camborough; avg parity = 2.92) were utilized to determine the SID Val:Lys requirement in lactating sows. Upon placement in farrowing, sows were randomly allotted by parity and BW into one of six dietary treatments (0.58, 0.65, 0.72, 0.79, 0.86, or 0.93 SID Val:Lys; 103 to 107 sows/trt) within a randomized complete block design. Diets were corn-SBM based diets with 2.5% added soy oil (3,294 kcal/kg). Single production batch SBM was obtained, analyzed for nutrient content, and used as the only SBM source for the entirety of the trial. Soybean meal inclusion rate was held constant across all treatments at 14.6%. Diets utilized crystalline Lys, Thr, Met, Trp, and Ile in order to target 59 g/d intake of SID Lys, while maintaining all other SID AA:Lys at 10% above NRC (2012) requirements. Crystalline Val was allowed into the diets to obtain the targeted SID Val:Lys levels. Once farrowed, sows were allowed ad lib access to their respective dietary treatment with feed deliveries recorded daily. Average lactation length during the trial was 19.1 days. Statistical analysis to identify effects of dietary treatment were performed using the MIXED procedure of SAS with the main effects of Val:Lys level, sow parity, and the potential interaction thereof. For break-point analysis, the NLMIXED procedure of SAS was utilized for linear broken-line regression. A quartic effect was observed for ADFI (6.47, 6.00, 6.19, 6.53, 6.14, and 6.29 kg/d, respectively; SEM = 0.32; P < 0.014) and sow BW loss (23.1, 28.7, 24.7, 20.6, 23.7, and 24.7 kg, respectively; SEM = 2.09; P < 0.015). A linear response (P < 0.006) in piglet weaning weight was observed when SID Val:Lys was increased from 0.58 to 0.65 (5.65, 5.82, 5.85, 5.83, 5.77, and 5.83 kg, respectively; SEM = 0.05). There was no further increase in weaning weight with SID Val:Lys greater than 0.65. Dietary SID Val:Lys had no impact (P > 0.05) on pre-wean mortality or sow wean-to-estrus length. Based upon this data, a SID Val:Lys levels as low as 0.65 can be fed without negatively impacting sow or piglet performance.

A total of 1,329 pigs (DNA 600) were used in a 42-d study to evaluate the effect of Ajitein (a fermentation biomass from lysine and threonine production) and Gold Pro (GP; a corn and yeast protein ingredient) on nursery performance as compared to enzymatically modified soybean meal (HP300). Pigs (BW = 7.2 ± 0.3 kg) were blocked by weight and sex and allocated across six dietary treatments for phases 1 (d 0-7) and 2 (d 7-21), with phase 3 (d 21-42) being a common diet. Pigs were not given any antibiotics through feed, water or injectables. All diets were formulated to meet or exceed NRC 2012 nutrient requirements and to be isocaloric and balanced to ideal protein using crystalline amino acids. Diets were balanced in terms of calcium and STTD phosphorus. Dietary treatments were a control containing HP300 (Treatment 1); Control with GP replacing HP300 (Treatment 2); Control with GP and Ajitein (1.5% then 0.75% of diet) replacing HP300 (Treatment 3); Control with Ajitein (3.0% then 1.5% of diet) replacing HP300 and GP (Treatment 4); and HP300 plus Ajitein (Treatment 5). There were no differences (P> 0.10) in BW and ADG during the entire study. Pigs fed HP300 + Ajitein (Treatment 5) exhibited increased (P< 0.02) ADFI during Phase 1, but control pigs (Treatment 1) exhibited the lowest ADFI and highest (P= 0.081) G:F. However, this G:F improvement did not carry over onto the succeeding phases or overall. Gold Pro alone or in combination with a low inclusion (13.6/6.8 kg/ton) of Ajitein tended to reduce mortality (P< 0.08) in Phase 1-2 (d 0-21). In conclusion, GP and Ajitein, singularly, or in combination, can effectively replace HP300 in nursery diets with equivalent results on growth performance.Table 1. Effects on growth and health performance (Overall)ItemTreatmentSEMP-value12345ADG, g333330319320318140.6651ADFI, g544531522517526150.7023G:F0.610.620.610.620.600.020.8161d 42 BW, kg21.921.621.221.521.10.60.6302Pigs treated/pen10.910.613.217.610.42.90.4200Mortality, %1.91.21.73.83.40.90.1800

An experiment was conducted with 430 sows (PIC Camborough) to evaluate the ideal standardized ileal digestibile (SID) Val:Lys on sow and litter performance during a 23-d lactation period. The SID Val:Lys ratios measured were based on previously published literature and then values above and below reported values. Sows were randomly allotted within parity block (parity 1, parity 2, and parity 3+) to one of five corn soybean meal based lactation diets formulated to contain different levels of SID Val:Lys (0.50, 0.62, 0.75, 0.88, and 1.00, respectively). All diets were formulated to be isocaloric (3.3 ME Mcal/kg) with 0.95% SID Lys and contained vitamins and minerals that exceeded recommendations (NRC, 2012). Experimental diets were given to sows from 112 d of pregnancy throughout the 23-d lactation period. Litters were standardized within 48 h after farrowing. Sows were fed with the Howema computerized feeding system that mixed the high and low diets to create the intermediate diets, weighed the feed for each sow and then delivered the feed to each individual feeding hopper to record daily sow feed intake during lactation. Data were analyzed as a randomized complete block design using the PROC MIXED procedure of SAS with sow as the experimental unit and treatment as a fixed effect and parity as the random effect. Results were considered significant at P≤ 0.05 and considered a trend at P >0.05 and P ≤0.10. Sow ADFI was not significantly different (6.0, 6.0, 5.9, 5.6, 6.1 ± 0.18 kg/d, respectively). On average, sows consumed approximately 57g of SID Lys per day. Sow wean to estrus (5.2, 4.7, 5.3, 5.5, 4.5 ± 0.32 d, respectively) had a tendency to be significantly different as the Val:Lys ratio changed. Increasing the Val:Lys ratio resulted in no differences (2.66, 2.64, 2.76, 2.61, 2.62 ± 0.08 kg; P> 0.10) in average daily litter gain. There were no differences in sow weight loss or subsequent total born across the dietary treatments. Overall, increasing levels of SID Val:Lys may result in a difference in sow reproductive performance with no major influence in the other parameters.

An experiment was conducted with 351 sows (PIC Camborough) to evaluate the effects of SID lysine intake on sow and litter performance during a 23-d lactation period. Sows were randomly allotted within parity block (parity 1, parity 2, and parity 3+) to one of five corn soybean meal based lactation diets formulated to contain different levels of SID lysine (49, 57, 65, 73, and 81 g/d, respectively). All diets were formulated to be isocaloric (3.3 ME Mcal/kg) and contained vitamins and minerals that exceeded recommendations (NRC, 2012). Experimental diets were given to sows from 112 d of pregnancy throughout the 23-d lactation period. Litters were standardized within 48 h after farrowing, and sows were allowed 5.9 kg of feed/d throughout the lactation period. Sows were fed with a computerized feeding system to record daily sow feed intake during lactation. Data were analyzed as a randomized complete block design using the PROC MIXED procedure of SAS with sow as the experimental unit and treatment as a fixed effect and parity as the random effect. Results were considered significant at P≤ 0.05 and considered a trend at P >0.05 and P ≤0.10. There were approximately 70 replications per treatment. Sow ADFI was lower (P>0.10) than calculated (5.14, 5.05, 5.20, 5.19, 5.15 kg/d) resulting in a SID Lys daily intake of 42.8, 48.9, 57.4, 64.5, 71.1, respectively. Increasing dietary lysine intake resulted in a significant linear increase (2.04, 2.42, 2.80, 3.16, 3.47; P< 0.05) in litter average daily gain as dietary lysine increased. There were no differences in wean to estrus interval, sow weight loss, or subsequent total born across the dietary treatments. Overall, increasing levels of SID lysine resulted in a linear increase in litter average daily gain during lactation with no major influence in the other parameters. The lower than expected lactation intake could have caused energy to be a limiting factor in this study.

The objective of this study was to test the hypothesis that feeding pregnant sows once-per-day diets reduced in CP concentration with concomitant incremental inclusion of crystalline AA (CAA) does not decrease whole body N retention of sows during the last week of pregnancy compared with sows fed a diet solely containing AA from feed ingredients. Two experiments were conducted, one with 28 pregnant gilts and another one with 25 pregnant multiparous sows (parity ≥ 3), each in 2 replications. Gilts and sows were allocated to 4 dietary treatments in a completely randomized design. Diets were corn–soybean meal based and contained 2,650 kcal/kg NE. The percent CP (analyzed) in diets were as followed for gilts and sows, respectively: 19.3 and 16.1 (control), 18.1 and 14.6 (Med), 16.1 and 12.6 (MedLow), and 14.2 and 11.6 (Low). Except for control diet, all diets contained CAA to meet the SID requirement for Lys, Thr, Trp, Met, and Ile during d 100 to 114 of gestation. The additional crystalline lysine in both gilt and sow diets was 0.13, 0.25, and 0.38% for the Med, MedLow, and Low diets, respectively. Sows were fed 2.21 kg once per day in the morning, starting at d 95. Analysis of N balance was conducted from d 105 to 110 of gestation by complete urine collection and the dietary marker (titanium oxide) dilution principle to determine fecal N output. Data were analyzed using a mixed model of SAS (SAS Inst. Inc., Cary, NC) and contrast statements were used to compare the Med, MedLow, and Low diets with the control diet. Number of piglets born alive, numbers stillborn and mummified piglets, and total litter weight at birth did not differ between low-protein diets and the control. In gilts, compared with the control diet (43.0 ± 2.48), N retention (g/d) did not differ (P= 0.18) in the Med diet (38.2 ± 2.48), tended to be lower (P= 0.09) in the MedLow diet (37.0 ± 2.48), and was lower (P= 0.04) in the Low diet (35.1 ± 2.70). In sows, compared with the control diet (37.9 ± 2.09), N retention did not differ (P= 0.14) in the Med diet (33.5 ± 1.93) and was lower for the MedLow (27.55 ± 1.76; P< 0.01) and Low diets (27.52 ± 1.90; P< 0.01). Feeding once-per-day diets reduced in CP beyond 2 percentage units to pregnant gilts and sows decreases N retention.

Two experiments evaluated standardized ileal digestible (SID) Ile:Lys on nursery pig growth performance. In Exp. 1, 280 pigs (PIC 327 × 1050, 6.7 kg BW) were fed experimental diets for 12 d with 8 replications and 5 pigs/pen. In Exp. 2, 280 pigs (DNA 600 × 241, 6.0 kg BW) were fed experimental diets for 18 d with 8 replications and 5 pigs/pen. Pens were allotted in a randomized complete block design to 1 of 7 treatments containing 40, 44, 48, 52, 54, 58, or 63% SID Ile:Lys. Dietary SID Lys was 1.28 and 1.24% for Exp. 1 and 2, respectively. Diets contained 1.5% spray dried blood cells and 10% field peas. Responses were evaluated with base models and dose response best fitting models. In Exp. 1, ADG increased linearly and ADFI and G:F had quadratic responses as SID Ile:Lys increased. For ADG, quadratic (QP), broken-line linear (BLL), and broken-line quadratic (BLQ) dose response models had similar fits reporting maximum ADG at 64.7, 52.0, and 52.0% SID Ile:Lys, respectively. For ADFI, BLL breakpoint occurred at 50.6% and QP maximum at 56.2% SID Ile:Lys. In Exp. 2, ADG and ADFI increased quadratically as SID Ile:Lys increased. For ADG, BLL and QP had similar fits with maximums at 51.8% and 58.3% SID Ile:Lys, respectively. For ADFI, QP maximum was 57.2% SID Ile:Lys and BLQ breakpoint at 52.0% SID Ile:Lys. In summary, the SID Ile:Lys requirement for 6 to 11 kg pigs ranges from 52% for ADG and ADFI using broken line models to as high as 64% using quadratic models.

A total of 2268 pigs (PIC 327×L42, initially 7.3 kg BW) were used in a 28-d growth study with 54 pigs/feeder (experimental unit) and 6 replications/treatment. Pigs were randomly allotted to pens at weaning and fed a common starter diet for 8 d. Pens were then blocked by BW and allotted to 1 of 7 dietary treatments in a randomized complete block design. Treatments were arranged in a [2 × 3]+1 factorial with 2 levels of standardized ileal digestible (SID) Lys, low (1.25%) and high (1.35%), and 3 SID amino acid (AA) ratios relative to Lys (industry, 95% of maximum performance, and maximum performance), as well as a control (1.35% SID Lys). Industry ratios were 55% Met+Cys:Lys, 62% Thr:Lys, 18% Trp:Lys, 65% Val:Lys, and 52% Ile:Lys. Maximum diet ratios were 60% Met+Cys:Lys, 65% Thr:Lys, 21% Trp:Lys, 72% Val:Lys, and 52% Ile:Lys. The 95% ratios were formulated to target 95% of maximum performance and were 56% Met+Cys:Lys, 62% Thr:Lys, 19% Trp:Lys, 67% Val:Lys, and 52% Ile:Lys. Diets were formulated to Ile requirement with feed-grade Lys, Met, Thr, Trp, and Val added. The control contained less feed-grade AA (0.39% L-Lys HCl vs. 0.50-0.55% in other diets) and 5% fermented soy protein to achieve similar soybean meal level to high SID Lys diets. Experimental diets were formulated using analyzed AA for corn, soybean meal, and dried distillers grains with solubles and fed for 14 d in meal form. Pens were weighed and feed disappearance was measured on d 0, 7, and 14. Data were analyzed using PROC GLIMMIX. From d 0 to 14, feeding high Lys diets increased (P< 0.001) ADG and G:F compared with low Lys diets with no evidence for differences in ADFI between Lys level. Furthermore, for ADG, maximum AA ratios improved (P< 0.05) performance compared to industry ratios at low Lys, but not at high Lys levels. In conclusion, higher AA ratios were more critical in diets formulated below the Lys requirement of the pig.

Diets containing animal protein sources have more glutamine than plant protein-based diets. AminoGut (Ajinomoto Heartland, Inc., Chicago, IL) is a product containing glutamine and glutamate. This study was conducted to determine the effects of protein source and AminoGut (Gln+Glu) on growth performance in nursery pigs from 5 to 27 kg. A total of 1,134 pigs (PIC 337 × 1050; 5.3 ± 0.08 kg) were used in a 52-d trial. Pens were assigned to treatments in a randomized complete block based on initial BW (7 pens/treatment). Treatments were a 2 × 3 factorial with 2 protein sources (animal [2.5% fish meal and 4% bovine blood plasma {d 0–10} and 5% fish meal {d 10–24}] vs. plant [6.5 {d 0–10} and 5% {d 10–24} fermented soy protein]) and 3 Gln+Glu durations (0, 10, and 24 d). Diets also contained 18 (d 0–10) and 25% (d 10–24) soybean meal. The Gln+Glu addition was 0.8% from d 0 to 10 and 0.6% from d 10 to 24. From d 24 to 52, pigs were fed a common diet. Statistical analysis was performed using PROC GLIMMIX (SAS; SAS Inst. Inc., Cary, NC). From d 0 to 10, pigs fed animal protein–based diets had marginally significant greater ADG (P= 0.074) and increased G:F (P= 0.016) compared with pigs fed plant-based diets; however, after d 10, no evidence of differences was observed between pigs fed different protein sources. From d 10 to 24, pigs fed Gln+Glu had increased ADG (P= 0.019) and G:F (P= 0.001). From d 0 to 24, pigs fed Gln+Glu had marginally significant improvement in ADG (P= 0.059) and increased G:F (P= 0.010) compared with pigs not fed Gln+Glu. From d 24 to 52, pigs previously fed Gln+Glu for 10 d had marginally significant improvement in G:F (P= 0.057) compared with pigs not fed Gln+Glu or fed Gln+Glu for 24 d. Overall (d 0–52), there was no evidence of differences in growth performance due to Gln+Glu. In conclusion, feeding Gln+Glu for 10 d after weaning improved growth performance until d 24, but there was no carryover effect when a common diet was fed, and dietary protein source did not influence the response to Gln+Glu. Further research should evaluate Gln+Glu supplementation for a longer duration.

An experiment was conducted to test the hypothesis that increased levels of fiber in diets fed to pigs would reduce N balance but be ameliorated with increased Thr. A total of 96 gilts (28.98 ± 2.0 kg initial BW) were housed in individual metabolism crates allowing for total and separate collection of feces and urine. Pigs were allotted to 12 diets (0.90% standardized ileal digestible [SID] Lys) with 8 replicate pigs per diet using a randomized complete block design. Diets were prepared in a 3 × 4 factorial arrangement with 3 levels of fiber (6, 11, or 15% NDF) added as wheat middlings and distiller's dried grains with solubles and 4 SID Thr:Lys concentrations (0.45, 0.50, 0.55, or 0.60). Pigs were fed experimental diets for 14 d, including a 7-d adaptation period and a subsequent 5-d urine and fecal collection period. Apparent total tract digestibility (ATTD), retention, and biological value (BV) of N were greatest (P< 0.05) for pigs fed diets containing 6% NDF. Retention and BV of N were greater (P< 0.05) in pigs fed diets with SID Thr:Lys ratios of 0.50, 0.55, and 0.60 than in pigs fed diets with a SID Thr:Lys ratio of 0.45. Results indicate that the optimal SID Thr:Lys ratio may increase with increased dietary fiber. Nitrogen balance in pigs fed diets containing 11% or more NDF may be increased with SID Thr:Lys ratios greater than 0.60.

Previous research has reported that increasing the SID Trp:Lys ratio to 24.5% in finishing pigs fed ractopamine HCl (RAC) during summer months improved ADG by 70 and 37 g/d in comparison with ratios of 18 and 21%, respectively. The objective of this experiment was to determine the effects of feeding higher SID Trp:Lys ratios with and without RAC on growth performance and carcass characteristics of finishing pigs during summer months. In August 2016 (mean outside temperature 23.03°C), a total of 1,101 pigs (PIC 1050 × 327; 99.3 kg initial BW) were used in a 30-d trial. Pens of 26 or 27 pigs were randomly assigned to 6 dietary treatments arranged in a 2 × 3 factorial with main effects of RAC (0 or 10 ppm) and SID Trp:Lys ratio (20, 24, and 28%) with 7 replications per treatment. Diets with and without RAC were formulated to 0.90 and 0.66% SID Lys, respectively. Overall (d 0 to 30), a RAC × SID Trp:Lys ratio interaction was observed (linear, P< 0.05), where increasing SID Trp:Lys ratios improved BW, ADG, and G:F when diets contained RAC but decreased these criteria when diets did not contain RAC. Similarly, RAC × SID Trp:Lys ratio interactions were observed (linear, P< 0.05) for carcass criteria with improvements in carcass ADG, carcass G:F, and HCW when pigs were fed increasing SID Trp:Lys ratios in diets containing RAC. A linear decrease (P< 0.05) was observed in carcass ADG and carcass G:F in pigs fed higher SID Trp:Lys ratios when diets did not contain RAC. In summary, increasing SID Trp:Lys ratio above 20% improved growth and carcass performance when diets contained RAC, whereas pigs fed higher SID Trp: Lys ratio above 20% had reduced performance when diets did not contain RAC.

A total of 45 gilts (165.7 ± 13.6 kg, 39.1 ± 2 d of gestation) were used in a 3-period N-balance study to evaluate the efficiency of utilizing SID Thr for whole body protein retention in gestating gilts. Gilts were randomly assigned to one of 4 diets set to provide 60, 70, 80 and 90% of the model-predicted daily SID Thr requirement for protein retention (NRC, 2012) at d 41–52 (6.46 g/d, Period I), d 68–79 (6.05 g/d, Period II) and d 96–107 (9.75 g/d, Period III) of gestation. Diets contained 3300 kcal/kg ME and 11.6% CP and given at a rate of 2.13 kg/d in Periods I and II and 2.53 kg/d in Period III to ensure energy was not limiting the response to Thr. The 12-d balance period was based on total urine collection using urinary catheters and determination of fecal N-digestibility using indigestible marker. Daily Thr retention was estimated based on NRC (2012) prediction of Thr content in each gestation pools. Thr efficiency (kSIDThr) was calculated as the ratio of daily Thr retention and daily SID Thr intake. Data were analyzed as RCB with diet as the fixed effect. The linear and quadratic response in whole-body N and Thr retention was tested within each balance period. Whole-body N and Thr retention were not affected by the dietary SID Thr levels for Periods I and II. In Period III, there was a linear increase (P<0.001) in whole body N and Thr retention. Efficiency of Thr use in period I, II, and III ranged from 0.22 to 0.32, 0.41 to 0.52, and 0.51 to 0.59, respectively. The lack of response in whole body protein retention in Periods I and II and the decreasing kSIDThr may in part reflect excess Thr intake. Efficiency of Thr use does not appear to be constant throughout gestation.

A previous study conducted by our group determined that the standardized ileal digestible (SID) His:Lys ratio requirement for 7- to 11-kg pigs ranged from 29.1 to 29.8%. The objective of this study was to validate the SID His:Lys ratio requirement by creating treatments more closely spaced around the expected requirement. A total of 350 pigs (DNA 600 × 241, initially 6.6 ± 0.36 kg) were used in a 14-d study. There were 10 replicates per treatment and 5 pigs per pen. Pens were blocked by weight and assigned to 1 of 7 dietary treatments containing 24, 28, 30, 32, 34, 36, or 42% SID His:Lys ratios in a randomized complete block design. Dietary SID Lys was 1.25% and all other amino acids met or exceeded the NRC (2012) requirement estimates. Diets were corn, spray-dried whey, and whey protein concentrate-based and treatments were formed by adding crystalline L-His at the expense of corn. Response variables ADG, ADFI, and G:F were fitted using general linear and nonlinear mixed models with heterogeneous variances and pen as the experimental unit. Competing models included quadratic polynomial, broken-line linear, and broken-line quadratic. For each response variable, the best fitting model was selected based on Bayesian Information Criterion. Increasing SID His:Lys ratio resulted in a linear increase (P < 0.01) in ADFI and quadratic responses (P < 0.01) in ADG and G:F. The response for ADFI was not modeled due to its linear nature. The best fitting model for ADG and G:F was the broken-line linear. For ADG, the requirement was estimated at 31.0% SID His:Lys (95% CI: 29.7 to 32.3%). The maximum mean G:F was obtained at 28.6% SID His:Lys (95% CI: 27.1 to 30.0%). In conclusion, the estimated SID His requirement for 7- to 11-kg pigs is no more than 31% of Lys.

Two experiments were conducted to estimate the standardized ileal digestible (SID) Val:Lys requirement for growth performance in 25- to 45-kg pigs. In Exp. 1, 1134 gilts (PIC 337), initially 31.2 kg (SD 2.0) BW, were used in a 19-d trial with 27 pigs/pen and 7 pens/treatment. In Exp. 2, 2100 gilts (PIC 327), initially 25.4 ± 1.9 kg BW, were used in a 22-d trial with 25 pigs/pen and 12 pens/treatment. In both experiments, treatments were blocked by initial BW in a randomized complete block design. In Exp. 1, there were 6 treatments with SID Val:Lys at 59.0, 62.5, 65.9, 69.6, 73.0, and 75.5%. For Exp. 2, there were 7 treatments with SID Val:Lys at 57.0, 60.6, 63.9, 67.5, 71.1, 74.4, and 78.0%. Diets were formulated to ensure that Lys was the second limiting AA throughout the experiments. Responses were analyzed separately for each experiment using general linear and nonlinear heteroskedastic mixed models, including initial BW as an explanatory covariate and BW block as a random effect. In Exp. 1, ADG linearly increased with increasing SID Val:Lys (P= 0.009; 680, 717, 717, 712, 744, and 726 ± 17.1 g, respectively), whereas no significant treatment differences were observed for G:F (0.467, 0.467, 0.472, 0.474, 0.481, and 0.472 ± 0.0084, respectively). In Exp. 2, ADG (quadratic, P= 0.002; 621, 662, 717, 708, 708, 726, and 717 ± 16.1 g, respectively) and G:F increased (linear, P< 0.001; 0.415, 0.420, 0.437, 0.429, 0.433, 0.441, and 0.439 ± 0.0046, respectively) with increasing SID Val:Lys. There was no evidence of experiment × treatment interaction. Therefore, data from the 2 experiments were combined for analysis using experiment and BW block within experiment as random effects. Competing models, namely a broken-line linear model, a broken-line quadratic model, and a quadratic polynomial (QP), were compared using Bayesian information criterion. In the combined analysis, the best-fitting model for ADG was a QP (prediction equation: −1.15 + 4.13 × SID Val:Lys − 2.78 × SID Val:Lys2+ 0.012 × initial BW) with optimum ADG estimated at 74.4% (95% confidence interval [CI] 69.5 to > 78.0) SID Val:Lys. The best-fitting model for G:F was also a QP (prediction equation: −0.04 + 1.36 × SID Val:Lys − 0.94 × SID Val:Lys2) with optimum G:F estimated at 72.3% (95% CI 64.0 to > 78.0) SID Val:Lys. In conclusion, 67% SID Val:Lys was able to capture 99% of maximum ADG and G:F in 25- to 45-kg pigs.

Camborough PIC sows (n= 255) were fed either increasing lysine levels or feeding amounts to determine the influence on piglet birth weight. Gestating sows (56 sows per pen) were fed with electronic sow feeding stations and had a body condition score of 3.00–3.25 on a 1–5 scale. One diet per pen was fed to minimize diet crossover. Litters were weighed within 16 h of birth. Sows were weighed at the initiation of the study, d 112 of gestation. Post-farrowing weight was calculated using a BW equation based on d 112 gestation weight. Data were analyzed using a randomized complete block design and treatment as the fixed effect, as well as, pairwise contrasts. In study one, females were fed 1 of 2 treatments (Control– 1.8 kg/d of feed (9 g SID lysine/d intake) or Bump– Control diet fed at 2.7 kg/d (14 g SID lysine/d)). P2 females were housed separately and were fed either Control (24 sows) or Bump (17 sows) diets for 2 wk due to pen allowance. P3+ females were fed diets for a period of 3 wk (40 Control and 45 Bump sows). For P3+ sows fed the Bump, 48-hr post farrow BW was higher (P= 0.02). Average piglet weight was not different (1.28 vs. 1.31 kg; P> 0.10). For the P2 females, average piglet weight (P> 0.10) and 48 h post-farrow body weight (181.8 vs. 189.7 kg; P> 0.10) was not different between treatments. Since there was no effect on bump feeding sows, primiparous females were fed 1 of 3 diets (Control– 1.8 kg/d (9 g SID lysine/d, 53 gilts); Bump– control diet fed at 2.7 kg/d (14 g SID lysine/d, 30 gilts); or High– 1.8 kg/d (13.5 g SID lysine/d, 46 gilts)) for 3 wk pre-farrow to determine the impact of different feeding programs on gilt litter performance in study 2. The Bump had lighter piglets at birth compared to the Control (1.12 vs. 1.24 kg; P= 0.04). However, this was likely due to the higher total born, which was not attributed to treatment (14.07 vs. 12.66 pigs). The High did not produce heavier piglets compared to the Control (1.28 vs. 1.24; P> 0.10) or reduce the percentage of < 0.90 kg pigs (10.11 vs. 11.32%; P> 0.10). Feeding increased Lys levels or additional feed to gestating animals in good body condition did not result in improved piglet birth weight.

Tryptophan is considered the second or third limiting amino acid in corn soybean-meal-based diets fed to growing and finishing swine. The NRC (2012) SID Trp:Lys ratio requirement for pigs above 165 lb is 17.7% of lysine. However, recent research has reported that increasing standardized ileal digestible (SID) Trp:Lys ratio above 20% in finishing pigs fed Ractopamine HCl (RAC) resulted in improved growth and carcass performance. To further evaluate this response, the objective of this experiment was to confirm the effects of feeding high SID Trp:Lys ratios in diets containing RAC on growth and carcass performance of finishing pigs from 110 to 135 kg. A total of 935 pigs (PIC 1050 × 337, initially 107.6 kg BW) were used in a 22-d trial. Pens of 23 or 24 pigs were allotted by BW and randomly assigned to 1 of 5 dietary treatments in a RCBD with 8 replications per treatment. The dietary treatments included 5 SID Trp:Lys ratios (20, 22, 24, 26, and 28% of Lys). Corn-soybean meal based diets were formulated to 0.90% SID Lys and contained 10 ppm ractopamine. Analyzed nutrients and total amino acids contents of experimental diets were consistent with formulated estimates. At d 22, pigs were transported to a packing plant for processing and carcass data collection. For overall growth performance, increasing SID Trp:Lys increased (linear, P= 0.007) ADFI (2.86, 2.91, 2.89, 2.96, and 3.00 kg) and SID Trp g/kg gain (5.2, 5.6, 6.4, 6.7, and 7.4) linear (P< 0.001). However, there was no evidence for treatment differences for ADG (1.10, 1.14, 1.10, 1.15, and 1.13 kg) or G:F (0.384, 0.390, 0.378, 0.390 and 0.376). Similarly, for carcass characteristics, there was no evidence for treatment differences for HCW, carcass yield, backfat loin depth, lean, carcass ADG or carcass feed efficiency. In summary, increasing SID Trp:Lys increased ADFI and SID Trp g/kg gain, however, there was no evidence for treatment differences for other growth or carcass parameters measured. Further research is necessary to determine why inconsistencies are observed when feeding high SID Trp:Lys ratios to finishing pigs.

An experiment was conducted to determine the standardized ileal digestible (SID) His:Lys ratio requirement for 7 to 11 kg pigs. A total of 360 pigs (DNA 600 × 241, initially 7.1 ± 0.31 kg BW) were fed experimental diets for 10 d with 12 replicates and 5 pigs per pen. Pens were blocked by weight and assigned in a randomized complete block design to 1 of 6 dietary treatments containing 24, 28, 32, 36, 40, or 44% SID His:Lys. Dietary SID Lys was 1.25% and all other AA met or exceeded the NRC (2012) requirement estimates. Diets were corn, spray-dried whey, and whey protein concentrate-based and treatments were formed by adding crystalline L-His at the expense of corn. Response variables ADG, ADFI, and G:F were fitted using general linear and nonlinear mixed models with heterogeneous variances and pen as the experimental unit. Competing models included quadratic polynomial, broken-line linear, and broken-line quadratic. For each response variable, the best fitting model was selected based on Bayesian Information Criterion. Increasing the His:Lys resulted in quadratic increases (P< 0.01) in ADG, ADFI, and G:F. The best fitting model for the three response variables was the broken-line linear. For ADG, the requirement was estimated at 29.7% SID His:Lys (95% CI: 27.8 to 31.6). For ADFI, the breakpoint occurred at 29.1% SID His:Lys (95% CI: 27.6 to 30.6). The maximum G:F was obtained at 29.8% SID His:Lys (95% CI: 27.6 to 32.1). In conclusion, the estimated SID His:Lys requirement for 7 to 11 kg pigs ranged from 29.1% to 29.8%.SID His:Lys, %SEM242832364044BW d 07.17.17.17.17.17.10.306BW d 10110.311.311.811.811.511.70.415ADG, g132742346947444846215.16ADFI, g146354157057256756619.59G:F10.7090.7820.8260.8290.7910.8180.0131Quadratic, P< 0.01

Two experiments were conducted to evaluate the effects of monosodium glutamate (MSG) on nursery pig performance. In Exp. 1, 1,134 nursery pigs (PIC 280 × 1050, initially 5.1 kg BW) were allotted to 6 treatments fed for 48 d. There were 27 pigs/pen and 7 pens/treatment. Dietary treatments contained 0, 0.5, 1.0, 1.5, and 2.0% MSG, or a high salt diet, formulated to an equal Na content as the 1.0% MSG diet. Experimental diets were fed in 3 phases from d 0 to 12, d 12 to 26, and d 26 to 48. During phase 1, no evidence for differences was detected among MSG treatments. In phase 2, increasing MSG decreased (linear, P<0.045) ADG, ADFI, and G:F while pigs fed the high salt diet (0.84% added salt) had decreased (P<0.001) ADG (254 vs. 317 g; SEM=11.3) and G:F (0.572 vs. 0.674; SEM=0.0154) compared with pigs fed the 1% MSG diet. In phase 3, pigs fed the high salt diet had decreased (P<0.028) ADG (528 vs. 561 g; SEM=10.1) and ADFI (797 vs. 851 g; SEM=17.3) compared with those fed the 1% MSG diet. For the overall nursery period, increasing MSG decreased (linear, P=0.033) ADG (388, 372, 378, 369, and 370 g for 0 to 2% MSG, respectively; SEM=7.9). Pigs fed the high salt diet had decreased (P<0.009) ADG (341 vs. 378 g; SEM=7.9), ADFI (546 vs. 578 g; SEM=12.2), and G:F (0.625 vs. 0.654; SEM=0.0044) compared to those fed 1% MSG. In Exp. 2, 700 nursery pigs (PIC C-29 × 1050, initially 6.2 kg BW) were allotted to 5 treatments fed for 42 d. There were 10 pigs/pen and 14 pens/treatment. Dietary treatments contained 0, 0.5, 1.0, 1.5, and 2.0% MSG and were balanced for Na and Cl using sodium bicarbonate and potassium chloride. Experimental diets were fed in 3 phases from d 0 to 14, d 14 to 28, and d 28 to 42. For ADG and ADFI, there was no evidence for differences within any phase or overall (ADG overall: linear, P=0.538; 464, 462, 458, 457, and 461 g, respectively; SEM=5.3). Increasing MSG resulted in poorer G:F (linear, P=0.003; 0.670, 0.660, 0.654, 0.654, and 0.645, respectively; SEM=0.0057) for phase 3. Thus, for the overall nursery period, G:F tended (quadratic, P=0.080) to be poorer with increasing MSG. In conclusion, MSG did not improve nursery pig performance and MSG may reduce intake and gain when dietary Na is not balanced.

Research indicates that dietary addition of AminoGut (product combining glutamine and glutamate; Ajinomoto Heartland, LLC, Chicago, IL) improves nursery pig performance; however, it is unknown whether the response is due to glutamine, glutamate, or their combination. In a 42-d study, 1,134 nursery pigs (PIC 359 × 1050, 4.9 kg BW) were used to determine the effects of monosodium glutamate (MSG), glutamine (Gln), or AminoGut on growth performance. Pigs were fed 6 dietary treatments in 2 phases from d 0 to 7 and 7 to 21 post-weaning. Treatments included a control diet, or the control with 0.5, 1.0, or 1.5% MSG, a combination of 1.0% MSG and 0.4% glutamine fed in both phases, or 0.8 and 0.6% AminoGut fed in phase 1 and 2, respectively. A common diet was fed from d 21 to 42. Pigs were assigned to pens at weaning and pens were assigned to treatment in BW blocks in a randomized complete block design with 7 replicate pens/treatment. Data were analyzed using Proc Mixed with pen as experimental unit. Linear and quadratic response to MSG was tested. Mean separation was used to determine response to Gln and AminoGut. During phase 1, there was no evidence for difference (P>0.453) for ADG, ADFI, or G:F with the addition of MSG, AminoGut, or MSG+Gln. There was no evidence feeding MSG improved ADG or ADFI (P>0.163) in phase 2, but marginally improved (linear, P=0.094) G:F. Pigs fed AminoGut had improved ADG (P<0.05) compared with all other treatments and increased (P<0.05) ADFI compared with pigs fed 0.5, 1.0, or 1.5% MSG. Feeding AminoGut resulted in improved (P<0.05) G:F compared with 0, 0.5, or 1.0% MSG, or MSG+Gln. There was no evidence for differences (P>0.105) during the common period or overall. There was no evidence feeding MSG alone or with Gln improved post-weaning growth performance; however, feeding AminoGut enhanced growth and feed efficiency from d 7 to 21 post-weaning compared with pigs fed the control diet.Control0.5% MSG1.0% MSG1.5% MSGMSG+GlnAminoGutSEMPhase 1 (d 0 to 7)ADG, g3320232633218.14ADFI, g1821951901901931915.64G:F0.1780.1050.1200.1280.1710.1070.0433Phase 2 (d 7 to 21)ADG, g262b,c251c262b,c263b,c271b296a7.5ADFI, g398a,b370c388b,c384b,c399a,b416a9.5G:F0.657b0.678b0.677b0.684a,b0.679b0.711a0.0118a,b,cMeans with different superscripts differ P<0.05.

Camborough PIC sows (n= 291) were fed one of five dietary treatments to evaluate the SID Thr:Lys requirement during lactation. Sows were blocked by parity (1, 2, and 3+) and randomly allotted to one of five SID Thr:Lys ratios (52, 60, 68, 76, and 84). SID Lys was formulated to 1.03% and SID M+C:Lys was 55%. Sows were allowed 5.45 kg/day starting on the day of farrowing. All other nutrients met or exceeded the NRC requirements. Sows were allowed ad libitum access to water and piglets were cross-fostered within treatment. Data collected during the study included: sow pre-farrow body weight, sow wean weight, starting litter weight, weaning litter weight, mortality, wean to estrus interval, and subsequent total born. Data were analyzed as a randomized complete block design using PROC MIXED with sow as the experimental unit and treatment and parity as fixed effects. Competing requirement estimation models were: quadratic polynomial (QP), broken-line linear (BLL), and broken-line quadratic (BLQ) using PROC NLMIXED. Models that differed in their Bayesian information criterion values by at least 2 points were considered to have meaningful differences in their data fit. The best-fit model was based on the best BIC value. As the SID Thr:Lys ratio increased, there was a quadratic response on ADFI (4.73, 4.57, 4.67, 4.55, and 4.60 kg/d; P= 0.001) and percent of sow body weight loss (−6.44, −7.89, −7.35, −6.19, and −5.81; P= 0.004). In addition, there was a trend for wean to estrus interval to be affected by the ratio (5.42, 4.42, 4.55, 4.46, and 4.84; P= 0.07). Daily litter gain was also quadratically improved as the SID Thr:Lys ratio increased (2.67, 2.67, 2.78, 2.77, and 2.68 kg/d; Pvalue = 0.001). For daily litter gain, the BLQ model was determined to be the best fit with an estimated SID Thr:Lys requirement of 65%. In conclusion, the optimal SID Thr:Lys ratio for litter growth is 65.

The current NRC recommended SID tryptophan-to-lysine ratio (Trp:Lys) for nursery pigs is 0.17 (NRC, 2012). However, studies in both high-health and health-challenged pigs have reported performance advantages with Trp:Lys from 0.20 to 0.26. Therefore, the objective of this experiment was to evaluate the impact of varying SID Trp:Lys on growth performance of nursery pigs. There were 5 dietary treatments with 9 pens (90 pigs) per treatment. Pigs were fed a common diet from d 0 to 7. The five dietary treatments with titrated SID Trp:Lys (0.150, 0.175, 0.200, 0.225, and 0.250) were fed from d 7 to 35 in two 2-wk dietary phases. Pigs were individually weighed, and feed remaining in feeders was weighed on d 0, 7, 14, 21, 28, and 35. Data were analyzed using PROC MIXED of SAS with block as a random effect. Pen was the experimental unit. Incremental body weight and the corresponding rate of gain and feed efficiency were analyzed as repeated measures. For each variable, normal distribution of residuals was tested using PROC UNIVARIATE. Determination of the optimal SID Trp:Lys of the 5 dietary treatment least squares means were analyzed using PROC REG for linear, quadratic, and broken line models. PROC NILN was utilized for exponential regression analysis. Over the entire experiment increasing Trp:Lys resulted in increased ADG (P= 0.002), decreased ADFI (P= 0.023), improved gain to feed ratio (P= 0.008), and increased BW exiting the nursery (d 35; P= 0.007). The relationship between Trp:Lys and overall G:F tended to be significant when fitted to an exponential curve (Fig. 3; P= 0.061), but not a linear, quadratic, or broken line curve (P≥ 0.244). These data indicate that there is no advantage in growth performance and feed efficiency to having a diet containing a SID Trp:Lys greater than 0.175 for nursery pigs. These data are supportive of the 0.17 Trp:Lys ratio specified by the NRC.

Lysine is the first limiting amino acid in practical swine diets, so it is important to optimize the dietary digestible lysine to maximize growth and profitability. Two experiments were conducted to estimate the standardized ileal digestible (SID) Lys requirement for pigs from 25- to 50-kg BW (Exp. 1) and 50- to 75-kg BW (Exp. 2) using ADG and G:F as criteria responses. A total of 1050 barrows and gilts (FAST F1 female × PIC380 boar line) were used in each experiment, blocked by gender, with 10 pens per treatment and 21 pigs per pen. Experimental diets were formulated to contain 2.3 Mcal NE/kg and to meet or exceed all nutrient requirements except Lys, according to NRC (2012). Minimum ratios of 30% Met:Lys, 60% Met + Cys:Lys, 21% Trp:Lys, 70% Val:Lys, 55% Ile:Lys, and 102% Leu:Lys on a SID basis were used for all diets. The SID Thr:Lys ratio was 65 and 66% for Exp. 1 and 2, respectively. In Exp. 1, pigs were fed diets formulated to contain 0.72, 0.80, 0.88, 0.96 or 1.04% SID Lys whereas in Exp. 2 diets were formulated to contain 0.68, 0.75, 0.82, 0.89 or 0.96% SID Lys. Responses measured at the pen level were analyzed using general linear and nonlinear heteroskedastic mixed models. Dose response curves were evaluated using linear (LM), quadratic polynomial (QP), broken-line linear (BLL), and broken-line quadratic (BLQ) models. For each response variable, the best-fitting model was selected using Bayesian information criterion. Gender was used as covariate when significant. Increasing SID Lys content in the diet quadratically (P< 0.01) increased ADG and G:F in Exp. 1 and linearly (P< 0.001) increased ADG and G:F in Exp. 2. From 25- to 50-kg, the best-fitting models for ADG and G:F were the LM and QP, respectively, with the maximum response estimated at > 1.04% SID Lys. From 50- to 75- kg BW, the best-fitting model for ADG was the BLQ estimating the requirement at 0.83% (95% confidence interval [CI]: [0.80%, 0.86%]) SID Lys, with 99% of maximum achieved with 0.82%. For G:F, the BLL was the best-fitting model and the SID Lys requirement estimated at 0.85% (95% CI: [0.75%, 0.94%]) with 99% of maximum achieved with 0.80%. In conclusion, the SID Lys requirement for 25- to 75-kg pigs may be higher than the recommendation from NRC (2012).

Barrows and gilts (PIC 29 × 380, n= 147) were blocked by initial BW (6.42 ± 1.21 kg) at weaning (21 ± 3 d) and allotted to pens (7 pigs/pen) within each of 7 blocks to evaluate the effects of aggressive feed-grade AA supplementation with reduced CP (RCP) diets formulated on either a ME or NE basis on growth performance of nursery pigs. Pens within blocks were randomly assigned to 1 of 3 treatments: 1) corn-SBM-corn DDGS-based diets formulated to meet the Trp requirement without addition of feed-grade Trp (feed-grade Trp was added in phase 3 to increase the Trp:Lys ratio from 17 to 19; Ctrl); 2) RCP diets formulated to meet the His:Lys ratio requirement (His:Lys = 32) without added feed-grade His and formulated on a ME basis (RCP-ME); or 3) RCP diets to meet the His:Lys requirement without feed-grade His and formulated on a NE basis (RCP-NE). Feed-grade AA were added to diets to meet all SID AA:Lys ratio requirements (M + C:Lys, 58; Thr:Lys, 60; Trp:Lys, 17 in phase 1 and 2 and 19 in phase 3; Ile:Lys, 55; Val:Lys, 65 in phase 1 and 2 and 70 in phase 3; His:Lys, 32) during each phase. During phases 1 and 2, feed-grade AA in RCP diets completely replaced poultry byproduct and partially replaced SBM in Ctrl diets. In phase 3, feed-grade AAs were included at the expense of SBM. Poultry fat was reduced in NE compared to ME-based diets. Neither ADG, ADFI, G:F, nor BW at the end of phases 1 and 2, as well as the end of the study, were affected (P≥ 0.40) by high inclusion levels of feed-grade AA in either ME- or NE-formulated diets. These results indicate that similar performance can be achieved with either ME- or NE-based nursery diets formulated to meet the His:Lys ratio without adding feed-grade His when supplemented with high levels of essential feed-grade amino acids to meet the AA:Lys ratios.

Previous research indicates aggressive feeding of AA to growing/finishing pigs results in reduced intake, gain, and fatter carcasses. This study investigated the role of dietary essential AA, nonessential AA, and electrolyte balance on these outcomes. PIC C29 × 380 pigs (n= 196) were blocked by BW and treatments assigned to gender-balanced pens within block. Treatments were: 1) corn-soybean meal diets formulated to meet a constant Trp:Lys ratio (20) without feed grade Trp (PC); 2) RCP diets meeting the His:Lys ratio requirement (32) without added feed grade His but with feed grade indispensable AA added to control levels (Met+Cys:Lys, 60 to 65; Thr:Lys, 65 to 68; Trp:Lys, 20; Ile:Lys, 73 to 78; Val:Lys, 79 to 88; His:Lys, 45 to 51; EAA); 3) as 2 but with feed grade Glu and Gly (67:33) added to the same N in PC (NEAA), or 4) as 3 but with diets formulated using NaHCO3to create the same dietary electrolyte balance as PC (dEB). All diets met the SID AA:Lys ratio requirement for each phase (23 to 41, 41 to 59, 59 to 82, 82 to 104, and 104 to 131 kg BW). Ractopamine (10 mg/kg) was fed during the last 3 wk. Pig BW and pen feed disappearance data were used to calculate ADG, ADFI, and G:F for each pen. HCW, LM and fat-depth (10th rib) were captured by Fat-O-Meter at slaughter. Pig growth performance and carcass composition were maintained by adding feed grade EAA to the RCP diet. ADG, ADFI, G:F and carcass characteristics did not respond to NEAA or NaHCO3additions. These results suggest the reduced performance of growing/finishing pigs fed RCP diets formulated to meet the His:Lys requirement without using feed grade His in previous studies may be attributed to improper AA:Lys ratios and not from total N or dietary electrolyte balance.

A total of 280 pigs (PIC 327 × 1050; initially 6.53 kg BW) were used in a 28-d trial to evaluate the effects of increasing standardized ileal digestible (SID) Val:Lys ratio on nursery pig growth performance. Pigs were weaned at 21 d of age and 5 pigs allotted to each nursery pen according to BW and gender. A common diet was fed for 5 d when pens were assigned to 1 of 7 dietary treatments in a randomized block design with 8 pens per treatment. Experimental diets were fed from d 0 to 14 followed by a common diet from d 14 to 28. The 7 dietary treatments were 50, 57, 63, 68, 73, 78, and 85% SID Val:Lys. A prior experiment demonstrated a Lys requirement of 1.44 and 1.45% SID Lys for ADG and G:F, respectively, for pigs in this facility. Thus, diets were formulated to 1.24% SID Lys to ensure pigs were below the Lys requirement. As SID Val:Lys increased, ADG, ADFI, and G:F increased (quadratic, P< 0.05). Growth response variables were fitted using linear and nonlinear dose–response models with pen as the experimental unit and initial BW as a covariate with ADG and G:F fitted using heterogeneous and homogenous residual variance, respectively. Models fit were quadratic polynomial (QP), broken-line linear (BLL), and broken-line quadratic with best fit determined according to Bayesian information criterion. For ADG, the best fitting model was BLL and maximum ADG was achieved with a minimum of 62.9% SID Val:Lys (95% CI: [52.2, 73.7%]). For G:F, the best fitting model was QP [0.010294 + 0.017526*(Val:Lys)– 0.000122*(Val:Lys)2] using a 6.53-kg initial BW. This resulted in a maximum G:F at 71.7% SID Val:Lys and 99% of maximum achieved at a 64.4% ratio. In summary, the SID Val:Lys requirement ranged from 62.9 to 71.7% depending on the response model.

A study was conducted to test the effects of liquid L-Lys supplementation on growth performance in growing-finishing pigs compared with crystalline L-Lys HCl. A total of 126 pigs at 70 d of age (29.5 kg BW) in 42 pens were randomly allotted to 7 dietary treatments which were, CON: a control diet without supplemental Lys meeting 75% of SID Lys requirement, Level 1 diets with crystalline L-Lys HCl (C1) or liquid L-Lys (L1) meeting 82% of SID Lys requirement, Level 2 (C2 or L2) diets meeting 89% of SID-Lys requirement and Level 3 (C3 or L3) diets meeting 96% of SID Lys requirement. Each treatment had 6 pens (3 barrow and 3 gilt pens) with 3 pigs/pen. All 7 diets were formulated to contain nutrients meeting the requirements suggested by NRC (2012) except for SID Lys. Pigs were fed experimental diets for 9 wk based on 3 phases until 90 kg BW (30 to 45, 45 to 75, and 75 to 90 kg BW, respectively). All experimental diets were pelleted. Body weight and feed disappearance were measured to calculate ADG, ADFI, and G:F. Data were analyzed using the MIXED procedure in SAS. A mutilinear regression analysis was used to evaluate the relative bioavailability of liquid L-Lys to crystalline L-Lys HCl. Increasing Lys from 75 to 96% of SID Lys requirement improved (P< 0.05) ADG from 0.83 to 1.00 kg/d and G:F from 0.384 to 0.430 without affecting ADFI. Forms of Lys (crystalline vs. liquid) did not affect performance of pigs. Rates of increases in ADG and G:F of pigs fed diets with liquid L-Lys was not different (P= 0.803 and 0.336) from that of pigs (39.4 vs. 37.0 g/g daily intake of supplemental Met and 0.00828 vs. 0.00696/g daily intake of supplemental Met) fed diets with crystalline L-Lys HCl. This study demonstrates that efficacy of liquid L-Lys is not different from that of crystalline L-Lys HCl for performance of pigs from 30 to 90 kg.

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