Evaluation of methods to reduce bacteria concentrations in spray-dried animal plasma and its effects on nursery pig performance

Four experiments with 1,040 weanling pigs (17 +/- 2 d of age at weaning) were conducted to evaluate the effects of spray-dried animal plasma source, drying technique, and methods of bacterial reduction on nursery pig performance. In Exp. 1, 180 barrows and gilts (initial BW 5.9 +/- 1.8 kg) were used to compare effects of animal plasma, animal plasma source, drying technique (spray-dried or freeze-dried), and plasma irradiation in nursery pig diets. From d 0 to 10, pigs fed diets containing irradiated spray-dried animal plasma had increased ADG and ADFI (P < 0.05) compared with pigs fed diets containing nonirradiated spray-dried animal plasma. Pigs fed irradiated animal plasma Sources 1 and 2 were similar in ADG and ADFI, but pigs fed animal plasma Source 1 had greater ADG (P < 0.05) than pigs fed animal plasma Source 2 and pigs not fed plasma. Pigs fed freeze-dried animal plasma had growth performance similar (P > 0.36) to pigs fed spray-dried animal plasma. Overall (d 0 to 24), pigs fed irradiated spray-dried animal plasma were heavier (P < 0.05) than pigs fed no animal plasma, whereas pigs fed nonirradiated spray-dried plasma were intermediate. In Exp. 2, 325 barrows and gilts (initial BW 5.8 +/- 1.7 kg) were used to compare the effects of irradiation or formaldehyde treatment of animal plasma and formaldehyde treatment of the whole diet. Pigs fed diets containing irradiated animal plasma had greater ADG (P < 0.05) than pigs fed nonirradiated plasma. Pigs fed formaldehyde-treated plasma had greater ADG and ADFI (P < 0.05) than pigs fed diets with either nonirradiated plasma or whole diet treated with formaldehyde. In Exp. 3 (360 barrows and gilts; initial BW 6.3 +/- 2.7 kg) and Exp. 4 (175 barrows and gilts; initial BW 6.1 +/- 1.7 kg), the irradiation of feed (high bacteria) and food-grade (low bacteria) animal plasma in nursery pig diets was examined. Pigs fed irradiated feed-grade plasma Product 2 had increased ADG (P < 0.05) compared with pigs fed nonirradiated plasma Product 2 and pigs fed the control diet without plasma. In Exp. 3 and 4, pigs fed irradiated food-grade plasma had growth performance similar to pigs fed nonirradiated food-grade plasma (P > 0.12). These studies indicate that bacterial reduction of feed-grade, but not food-grade animal plasma, improves nursery pig performance.     

Effects of protein deprivation on subsequent growth performance,gain of body components,and protein requirements in growing pigs

Forty-eight barrows were used in a 2 x 6 factorial arrangement to test a hypothesis that feeding a protein-deficient diet affects subsequent growth response by altering the efficiency of protein utilization. Barrows were individually fed either a 9% crude protein (CP) diet or an 18% CP diet from 20 to 30 kg of body weight (BW) (depletion phase). From 30 to 45 kg BW (realimentation phase), pigs were fed one of six experimental diets with CP levels of 11.8, 13.1, 14.3, 15.6, 18.8, and 21.8%. Four pigs were slaughtered at 20 kg BW to determine initial body composition. Four pigs from each treatment in depletion phase (a total of eight) were slaughtered at 30 kg BW, and all pigs from each treatment in realimentation phase (a total of 36) were slaughtered at 45 kg BW for subsequent compositional analysis. Pigs were bled at 20, 30, and 40 kg BW for blood urea nitrogen (BUN), insulin-like growth factor (IGF)-I, and IGF-binding protein (IGFBP) assays. Pigs were given three times the maintenance digestible energy requirement (3 x 120 kcal BW(-0.75) x d(-1)) in three equal meals daily. The feed allowance was adjusted every 3 d. During the depletion phase, pigs fed the 18% CP diet grew faster and more efficiently (P < 0.01) and gained more (P < 0.01) water and protein than did pigs fed the 9% CP diet. Pigs fed the 18% CP diet showed higher (P < 0.01) BUN values, IGF-I concentrations, and IGFBP ratios than pigs fed the 9% CP diet. During the realimentation phase, pigs fed the 9% CP diet during the depletion phase grew faster (P < 0.05), tended to grow more efficiently (P = 0.066), gained more water (P < 0.01), and tended to gain more protein (P = 0.068) than pigs fed the 18% CP diet during the depletion phase. Pigs fed the 9% CP diet during the depletion phase tended (P = 0.069) to have a higher protein requirement during the realimentation phase than pigs fed the 18% CP diet during the depletion phase. When measured at 40 kg BW, pigs fed the 9% CP diet had a lower (P < 0.05) BUN than pigs fed the 18% CP diet during the depletion phase. However, the plasma IGF-I concentration and IGFBP ratio at 40 kg BW were not affected by dietary CP level fed during the depletion phase. This study indicates that pigs fed a protein-deficient diet exhibit compensatory growth. During the period of compensatory growth, the requirement of CP for those pigs is higher than that of pigs previously fed an adequate diet. This study also suggests BUN can be used as an indicator of protein utilization efficiency and compensatory growth.     

Sulfur concentration in diets containing corn, soybean meal, and distillers dried grains with solubles does not affect feed preference or growth performance of weanling or growing-finishing pigs

Four experiments were conducted to investigate the effects of distillers dried grains with solubles (DDGS) and dietary S on feed preference and performance of pigs. In a 10-d feed preference experiment (Exp. 1), 48 barrows (20.1 ± 2.2 kg of BW) were randomly allotted to 3 treatment groups, with 8 replicate pens per treatment and 2 pigs per pen. A control diet based on corn and soybean meal, a DDGS diet containing 20% DDGS, and a DDGS-sulfur (DDGS-S) diet were prepared. The DDGS-S diet was similar to the DDGS diet with the exception that 0.74% CaSO(4) was added to the diet. Two diets were provided in separate feeders in each pen: 1) the control diet and the DDGS diet, 2) the control diet and the DDGS-S diet, or 3) the DDGS diet and the DDGS-S diet. Preference for the DDGS diet and the DDGS-S diet vs. the control diet was 35.2 and 32.6%, respectively (P < 0.05), but there was no difference between the DDGS diet and the DDGS-S diet. In Exp. 2, a total of 90 barrows (10.3 ± 1.4 kg of BW) were allotted to 3 treatments, with 10 replicate pens and 3 pigs per pen, and were fed the diets used in Exp. 1 for 28 d, but only 1 diet was provided per pen. Pigs fed the control diet gained more BW (497 vs. 423 and 416 g/d; P < 0.05) and had greater G:F (0.540 vs. 0.471 and 0.455; P < 0.05) than pigs fed the DDGS or the DDGS-S diet, but no differences between the DDGS and the DDGS-S diets were observed. In a 10-d feed preference experiment (Exp. 3), 30 barrows (49.6 ± 2.3 kg of BW) were allotted to 3 treatment groups, with 10 replicates per group. The experimental procedures were the same as in Exp. 1, except that 30% DDGS was included in the DDGS and DDGS-S diets and 1.10% CaSO(4) was added to the DDGS-S diet. Feed preference for the DDGS and the DDGS-S diets, compared with the control diet, was 29.8 and 32.9%, respectively (P < 0.01), but there was no difference between the DDGS and the DDGS-S diets. In Exp. 4, a total of 120 barrows (34.2 ± 2.3 kg of BW) were fed grower diets for 42 d and finisher diets for 42 d. Diets were formulated as in Exp. 3. Pigs on the control diets gained more BW (1,021 vs. 912 and 907 g/d; P < 0.05) and had greater G:F (0.335 vs. 0.316 and 0.307; P < 0.05) than pigs fed the DDGS or DDGS-S diet, respectively, but no differences between pigs fed the DDGS and the DDGS-S diets were observed. In conclusion, dietary S concentration does not negatively affect feed preference, feed intake, or growth performance of weanling or growing-finishing pigs fed diets based on corn, soybean meal, and DDGS.     

Influence of dietary protein level, amino acid supplementation, and dietary energy levels on growing-finishing pig performance and carcass composition

Two experiments were conducted to determine the effects of feeding reduced-CP, AA-supplemented diets at two ambient temperatures (Exp. 1) or three levels of dietary NE (Exp. 2) on pig performance and carcass composition. In Exp. 1, 240 mixed-sex pigs were used to test whether projected differences in heat increment associated with diet composition affect pig performance. There were 10 replications of each treatment with four pigs per pen. For the 28-d trial, average initial and final BW were 28.7 kg and 47.5 kg, respectively. Pigs were maintained in a thermoneutral (23 degrees C) or heat-stressed (33 degrees C) environment and fed a 16% CP diet, a 12% CP diet, or a 12% CP diet supplemented with crystalline Lys, Trp, and Thr (on an as-fed basis). Pigs gained at similar rates when fed the 16% CP diet or the 12% CP diet supplemented with Lys, Trp, and Thr (P > 0.10). Pigs fed the 12% CP, AA-supplemented diet had a gain:feed similar to pigs fed the 16% CP diet when housed in the 23 degrees C environment but had a lower gain:feed in the 33 degrees C environment (diet x temperature, P < 0.01). In Exp. 2, 702 gilts were allotted to six treatments with nine replicates per treatment. Average initial and final BW were 25.3 and 109.7 kg, respectively. Gilts were fed two levels of CP (high CP with minimal crystalline AA supplementation or low CP with supplementation of Lys, Trp, Thr, and Met) and three levels of NE (high, medium, or low) in a 2 x 3 factorial arrangement. A four-phase feeding program was used, with diets containing apparent digestible Lys levels of 0.96, 0.75, 0.60, and 0.48% switched at a pig BW of 41.0, 58.8, and 82.3 kg, respectively. Pigs fed the low-CP, AA-supplemented diets had rates of growth and feed intake similar to pigs fed the high-CP diets. Dietary NE interacted with CP level for gain:feed (P < 0.06). A decrease in dietary NE from the highest NE level decreased gain:feed in pigs fed the high-CP diet; however, gain:feed declined in pigs fed the low-CP, AA-supplemented diet only when dietary NE was decreased to the lowest level. There was a slight reduction in longissimus area in pigs fed the low-CP diets (P < 0.08), but other estimates of carcass muscle did not differ (P > 0.10). These data suggest that pigs fed low-CP, AA-supplemented diets have performance and carcass characteristics similar to pigs fed higher levels of CP and that alterations in dietary NE do not have a discernible effect on pig performance or carcass composition.     

Effects of betaine, pen space, and slaughter handling method on growth performance, carcass traits, and pork quality of finishing barrows

An experiment was conducted to determine the effects of betaine, pen space, and preslaughter handling method on growth, carcass traits, and pork quality of finishing barrows. For the growth trial, a 2 x 2 factorial arrangement of treatments was used: betaine (0 or 0.250%) and(or) pen space (m2/pig; adequate, 0.035 BW0.67 kg, or inadequate, 0.025 BW0.67 kg). Each treatment was replicated five times with four barrows per replicate. At trial termination, two barrows from each pen were selected to receive either minimal or normal preslaughter handling. Reducing pen space decreased (P < 0.05) overall ADG and gain:feed and tended (P = 0.12) to decrease overall ADFI. Betaine had no affect (P > 0.10) on overall ADG, ADFI, or gain:feed. Pigs fed betaine had decreased (P < 0.10) carcass length. Other carcass and ham measurements were not affected (P > 0.10) by betaine. Pigs with inadequate pen space had increased (P < 0.10) ultimate pH, subjective color, cooking loss (fresh and frozen chop), and shear force but decreased rectal temperature, loin muscle CIE L*, biceps femoris CIE b*, and drip loss. Pigs subjected to minimal preslaughter handling had decreased (P < 0.10) rectal temperature, plasma cortisol, loin muscle CIE b*, and fresh chop total loss (drip + cooking loss). Pigs fed betaine had increased (P < 0.01) initial pH and decreased (P < 0.10) drip loss (fresh chop). Cooking loss and total loss (frozen chop) were decreased in pigs fed betaine with adequate pen space but increased in pigs fed betaine with inadequate pen space (betaine x pen space, P < 0.01). Pigs fed betaine may have improved pork quality.     

The effects of poultry meal source and ash level on nursery pig performance

Weanling pigs (total of 560) were used in two experiments to determine the effects of poultry meal in nursery diets on pig performance. In Exp. 1,210 barrows and gilts (initially 7.4 kg and 21 +/- 2 d of age) were fed one of five diets, which included a control diet with no specialty protein products or (as-fed basis) the control with 2.5 or 5.0% fish meal, or 2.9 or 5.9% poultry meal (11.8% ash). Poultry meal replaced fish meal on an equal lysine basis. Overall (d 0 to 28), pigs fed diets containing fish meal had greater (P < 0.01) ADG than pigs fed poultry meal. Increasing fish meal tended to have increased (quadratic, P < 0.07) ADG, with the greatest improvement observed in pigs fed the diet containing 2.5% fish meal. Pigs fed diets containing fish meal had improved (P < 0.01) G:F compared with pigs fed diets containing poultry meal. In Exp. 2, a total of 350 barrows and gilts (initially 8.9 kg and 22 +/- 2 d of age) were fed one of seven experimental diets, which included a control diet with no specialty protein products, or the control with 2.5 or 5.0% fish meal, 2.9 or 5.8% low-ash (10.9%) poultry meal, and 3.1 or 6.2% high-ash (13.5%) poultry meal. Poultry meal replaced fish meal on an equal lysine basis. Overall (d 0 to 15), there were no differences in ADG and ADFI (P = 0.14); however, pigs fed diets containing fish meal or poultry meal had improved (linear, P < 0.01) G:F compared with pigs fed the control diet. Pigs fed diets containing low-ash poultry meal had greater (P < 0.01) G:F compared with pigs fed diets containing high-ash poultry meal. Based on these data, quality control specifications, such as ash content, need to be considered when using poultry meal as an animal protein replacement in diets for nursery pigs.     

Effect of microbial phytase on energy availability,and lipid and protein deposition in growing swine

Two experiments were conducted to determine the effect of phytase on energy availability in pigs. In Exp. 1, barrows (initial and final BW of 26 and 52 kg) were allotted to four treatments in a 2 x 2 factorial arrangement. Corn-soybean meal (C-SBM) diets were fed at two energy levels (2.9 and 3.2 x maintenance [M]) with and without the addition of 500 phytase units/kg of diet. The diets contained 115% of the requirement for Ca, available P (aP), and total lysine, and Ca and aP were decreased by 0.10% in diets with added phytase. Pigs were penned individually and fed daily at 0600 and 1700, and water was available constantly. Eight pigs were killed and ground to determine initial body composition. At the end of Exp. 1, all 48 pigs were killed for determination of carcass traits and protein and fat content by total-body electrical conductivity (TOBEC) analysis. Six pigs per treatment were ground for chemical composition. In Exp. 2, 64 barrows and gilts (initial and final BW of 23 and 47 kg) were allotted to two treatments (C-SBM with 10% defatted rice bran or that diet with reduced Ca and aP and 500 phytase units/kg of diet), with five replicate pens of barrows and three replicate pens of gilts (four pigs per pen). In Exp. 1, ADG was increased (P < 0.01) in pigs fed at 3.2 x M. Based on chemical analyses, fat deposition, kilograms of fat, retained energy (RE) in the carcass and in the carcass + viscera, fat deposition in the organs, and kilograms of protein in the carcass were increased (P < 0.10) in pigs fed the diets at 3.2 vs. 2.9 x M. Based on TOBEC analysis, fat deposition, percentage of fat increase, and RE were increased (P < 0.09) in pigs fed at 3.2 x M. Plasma urea N concentrations were increased in pigs fed at 3.2 x M with no added phytase but were not affected when phytase was added to the diet (phytase x energy, P < 0.06). Fasting plasma glucose measured on d 28, ultrasound longissimus muscle area (LMA), and 10th-rib fat depth were increased (P < 0.08) in pigs fed phytase, but many other response variables were numerically affected by phytase addition. In Exp. 2, phytase had no effect (P > 0.10) on ADG, ADFI, gain:feed, LMA, or 10th-rib fat depth. These results suggest that phytase had small, mostly nonsignificant effects on energy availability in diets for growing pigs; however, given that phytase increased most of the response variables measured, further research on its possible effects on energy availability seems warranted.     

Effects of different cereal grains and ractopamine hydrochloride on performance, carcass characteristics, and fat quality in late-finishing pigs

Forty-eight barrows and forty-eight gilts (PIC 337 sires x PIC C22 dams) were evaluated to determine the effects of feeding ractopamine hydrochloride (RAC) and different cereal grains on the carcass and fat quality in late finishing pigs. The study was carried out using four replicates with 24 animals in each replicate (four pigs per pen, six pens per replicate, two replicates per slaughter date, 12 pens per slaughter date). Treatments for the experiment included corn, wheat, and barley (early finisher period); and corn, corn + RAC, wheat, wheat + RAC, barley, and barley + RAC for the late finisher period. Ractopamine was fed at the level of 10 mg/kg (as-fed basis) of feed. Pigs were allotted to early finisher period treatments at approximately 45 kg BW. Pigs were then given late finisher period treatments at approximately 80 kg BW and fed for 28 d. The dietary digestible lysine level for all diets was maintained at 2.7 g/Mcal of ME. Pigs fed the wheat and corn diets during the late finisher period had a greater (P <0.05) G:F than those fed the barley diets. Pigs fed diets with RAC had lower (P <0.05) leaf fat weights, 10th-rib fat, last-rib fat, and belly firmness and had improved (P <0.05) dressing percents and loin muscle areas compared with those not receiving RAC. Pigs fed the wheat diets had a greater (P <0.05) dressing percent than those receiving the barley diets, but pigs fed the barley diets had a higher (P <0.05) Minolta L* for fat color than pigs fed wheat. Pigs fed diets containing RAC produced pork that was less tender (P <0.05) compared with pigs that did not receive RAC. Linoleic acid percent values were higher (P <0.05) for pigs fed diets with RAC than in those that did not. Feeding RAC improved G:F and lowered feed intake of pigs during the late finisher period (P <0.05). Feeding diets equal in lysine (2.7 g/Mcal of ME) but varying in ME, whether based on corn, wheat, or barley with or without RAC, had little to no effect on carcass, meat, or fat quality attributes.     

Dietary betaine supplementation affects energy metabolism of pigs

The effect of dietary betaine supplementation on energy partitioning in growing pigs under energy-restricted dietary conditions was assessed. The effect of betaine on the adaptation in energy metabolism of pigs over time after a change in diet and housing also was studied. Six groups of 14 group-housed barrows were assigned to one of two experimental diets: control or betaine-supplemented (0 or 1.29 g/kg of feed). Diets were corn- and soybean meal-based and were formulated to be limiting in energy content but sufficient in amino acids. The experiment comprised a 3-wk adaptation and a 3-wk experimental period. At the start of the experimental period, initial BW was 46 kg, each group of pigs was housed in a climate-controlled respiration chamber, and all pigs were subjected to a change in diet. During the experimental period, diets were diluted with 10% oat hulls. Pigs were fed at 2.5 times the energy requirements for maintenance, and during the experimental period, heat production, energy, and nitrogen balances were measured weekly. Metabolizibility of energy did not differ (P > 0.10) between diets. Averaged over the experimental period, betaine reduced heat production (P < 0.05) and energy requirements for maintenance (P < 0.10) and consequently increased energy retention (P < 0.10). Moreover, the difference in heat production between diets increased with time (P < 0.05). Similarly, the effect of betaine on the energy requirements for maintenance changed with time (P < 0.05). Maintenance requirements were similar in wk 1 and were decreased by betaine supplementation by 5.5% during wk 3 (477 vs. 452 kJ/[kg(0.75) x d]). Results of this study show that dietary betaine supplementation affects energy partitioning by growing pigs. However, based on the observed time-related changes in energy partitioning, it was concluded that dietary betaine supplementation did not influence adaptation by pigs to a change in housing and diet.     

Pigs weaned from the sow at 10 days of age respond to dietary energy source of manufactured liquid diets and exogenous porcine somatotropin

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 microg of pST.kg BW(-1).d(-1) for 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.     

Evaluation of sex and lysine during the nursery period

Split-sex feeding in the grow-finish period of swine production was an innovative technology of the last decade because of the different growth rates, feed efficiencies, and perhaps different nutrient needs between gilts and barrows. However, due to various weaning strategies, split-sex feeding has not been adequately evaluated in the nursery. The objectives of our research were to determine 1) if gilts and barrows responded similarly to increased protein (Lys) after weaning, and 2) if the current NRC estimated requirements for Lys are adequate. Six experiment stations (KS, KY, MI, MN, OH, and SD) utilized 748 pigs (6.7 kg of BW; 19.4 +/- 1.1 d of age). The pigs were allotted to 4 treatments in 32 replications (5 to 7 pigs/pen) in a randomized complete block design. Barrows and gilts were penned separately, and complex nursery diets were fed in 3 phases (d 1 to 7, 8 to 21, and 22 to 35). Lysine was provided at the NRC estimated requirements or at 0.20% greater (1.35 vs. 1.55%, 1.25 vs. 1.45%, and 1.15 vs. 1.35% for the 3 phases, respectively). Pigs and feed were weighed initially and at the end of each phase. The results demonstrated that sex did not affect ADG, ADFI, or G:F in any phase or during the 35-d study (453 vs. 452 g/d, 674 vs. 675 g/d, and 0.673 vs. 0.671 for barrows and gilts, respectively). The greater Lys concentration improved ADG in phase 3 (628 vs. 589 g; P < 0.001) and overall (465 vs. 441 g; P < 0.001) compared with pigs fed the NRC-estimated Lys requirements. Increased Lys in the diet increased ADFI in phase 2 (P < 0.05), but not in the other phases or for the overall 35-d study. Gain:feed was improved by feeding greater Lys concentrations in phase 2 (0.785 vs. 0.704; P < 0.001) and in the overall 35-d experiment (0.695 vs. 0.649; P < 0.001). There was no evidence of a sex x Lys interaction (P = 0.33) for any of the response variables during any of the phases or overall. Our results demonstrate that increasing Lys concentrations in nursery diets results in improved pig performance of both sexes, and there appears to be no benefit to split-sex feeding when mixed genotypes are fed in the nursery.     

The effects of thermal environment and spray-dried plasma on the acute-phase response of pigs challenged with lipopolysaccharide

Forty barrows (TR4 x C22) were weaned at 17 d of age (BW = 6.27 +/- 0.30 kg), housed (two pigs/pen) in a thermal-neutral environment (TN; constant 26.7 degrees C), and fed diets with or without 7% (as-fed basis) spray-dried plasma (SDP). On d 7, one pig/ pen was moved into a cold environment (CE; constant 15.6 degrees C). Pigs were fitted with jugular catheters on d 11. On d 12, 16 pigs per environment (eight pigs per dietary treatment) were challenged i.v. with 75 microg of lipopolysaccharide (LPS)/kg of BW. Blood samples were collected over a 4.5-h period. Pigs were then killed and tissue samples were harvested for messenger RNA (mRNA) analysis. From d 0 to 7, pigs fed SDP diets had a lower gain:feed ratio (G/F) than pigs fed no SDP (533 +/- 14 vs. 585 +/- 17 g/kg; P < 0.03). Pigs housed in the CE consumed more feed and had a lower G/F than pigs housed in TN from d 7 to 11 (P < 0.001). There were no environment x diet interactions from d 7 to 11 (P > 0.78). Baseline concentrations of serum ACTH and cortisol were lower in the TN pigs than in the CE pigs (P < 0.001). Pigs fed diets without SDP had lower serum cortisol concentrations over the 4.5-h period than pigs fed SDP (time x diet, P < 0.001). Serum concentrations of tumor necrosis factor-alpha (TNF-alpha) were highest for pigs consuming SDP in the CE, whereas there were no differences among the other treatments (time x diet x environment, P < 0.02). Pigs housed in the CE had higher serum interleukin-1beta (IL-1beta) (P < 0.001) and interleukin-6 (IL-6; P < 0.001) than TN pigs. Pigs fed SDP also had slightly higher serum IL-1beta concentrations (P < 0.10) and higher (P < 0.001) IL-6 concentrations than pigs fed no SDP. Pigs fed SDP had 9% lower liver and 13% lower thymus mRNA expression of tumor necrosis factor-alpha (TNF-alpha) than pigs that consumed no SDP (P < 0.06). Liver IL-1beta, IL-6, and LPS-binding protein mRNA were higher in the CE than in the TN (P < 0.03, P < 0.001, and P < 0.05; respectively). In addition, spleen TNF-alpha (P < 0.03) and IL-6 (P < 0.01) mRNA levels were higher in the CE than in the TN. Pigs consuming SDP and challenged with LPS responded with elevated serum concentrations of cortisol and cytokines compared with pigs fed diets with no SDP. Housing pigs in a CE increased the baseline concentrations of ACTH and cortisol, and when coupled with an LPS challenge, resulted in elevated serum and tissue mRNA levels of cytokines. Cold stress and feeding SDP during a LPS challenge may result in increased stress and immune responses in young pigs.     

Effect of dietary L-carnitine on growth performance and body composition in nursery and growing-finishing pigs.

Two experiments were conducted to determine the effect of dietary L-carnitine on growth performance and carcass composition of nursery and growing-finishing pigs. In Exp. 1,216 weanling pigs (initially 4.9 kg and 19 to 23 d of age) were used in a 35-d growth trial. Pigs were blocked by weight in a randomized complete block design (six pigs per pen and six pens per treatment). Four barrows and four gilts were used to determine initial carcass composition. L-Carnitine replaced ground corn in the control diets to provide 250, 500, 750, 1,000, or 1,250 ppm. On d 35, three barrows and three gilts per treatment (one pig/block) were killed to provide carcass compositions. L-Carnitine had no effect (P > 0.10) on growth, percentages of carcass CP and lipid, or daily protein accretion. However, daily lipid accretion tended to decrease and then return to values similar to those for control pigs (quadratic P < 0.10) with increasing dietary L-carnitine. In Exp. 2, 96 crossbred pigs (initially 34.0 kg BW) were used to investigate the effect of increasing dietary L-carnitine in growing-finishing pigs. Pigs (48 barrows and 48 gilts) were blocked by weight and sex in a randomized complete block design (two pigs/pen and eight pens/treatment). Dietary L-carnitine replaced cornstarch in the control diet to provide 25, 50, 75, 100, and 125 ppm in grower (34 to 56.7 kg; 1.0% lysine) and finisher (56.7 to 103 kg; 0.80% lysine) diets. At 103 kg, one pig/pen was slaughtered, and standard carcass measurements were obtained. Dietary L-carnitine did not influence growth performance (P > 0.10). However, increasing dietary carnitine decreased average and tenth-rib back-fat (quadratic, P < 0.10 and 0.05), and increased percentage lean and daily CP accretion rate (quadratic, P < 0.05). Break point analysis projected the optimal dosage to be between 49 and 64 ppm of L-carnitine for these carcass traits. It is concluded that dietary carnitine fed during the nursery or growing-finishing phase had no effect on growth performance; however, feeding 49 to 64 ppm of L-carnitine during the growing-finishing phase increased CP accretion and decreased tenth-rib backfat.     

Synergistic effects of betaine and conjugated linoleic acid on the growth and carcass composition of growing Iberian pigs

An experiment was conducted to determine the efficacy of dietary betaine, CLA, or both as growth promotants and carcass modifiers in growing Iberian pigs. Twenty gilts (20 kg of BW) were individually penned and fed barley- and soybean meal-based diets (12% CP, 0.81% Lys, and 14.8 MJ of ME/kg of DM) containing either no added betaine or CLA (control), 0.5% betaine, 1% CLA, or 0.5% betaine + 1% CLA, at 95% of ad libitum energy intake. An additional group of 5 pigs was slaughtered at the beginning of the experiment to obtain the initial body composition. At 30 kg of BW, a balance experiment was conducted. At 50 kg of BW, pigs were slaughtered and viscera was removed and weighed. Betaine or CLA alone did not affect growth performance. However, betaine + CLA increased ADG (601 vs. 558 g, P = 0.03) and gain relative to ME intake (25.4 vs. 22.2 g/MJ, P = 0.03) compared with control pigs. Digestibility of nutrients and metabolizability of energy did not differ among diets (P = 0.46 to 0.75). Carcass protein, water, and lean deposition (g/d) increased (19.8, 24.2, and 23.4%, respectively, P < 0.01) in pigs fed betaine + CLA compared with control pigs. Similarly, protein deposition relative to ME intake increased by 28% in betaine + CLA-supplemented pigs (P < 0.05). Fat and mineral deposition did not differ among treatments. Carcass protein, water, and lean content (g/kg of carcass) of pigs fed betaine + CLA-supplemented diets tended to increase (P = 0.07 to 0.09) and carcass fat content tended to decrease (P = 0.09). Similarly, estimated composition of carcass gain was affected, such that water and lean content tended to increase (P = 0.06 to 0.08), whereas fat tended to decrease (P = 0.08) in pigs fed betaine + CLA-supplemented diets. Longissimus muscle area was not altered by treatments (P = 0.49). The liver of pigs fed betaine + CLA diets had increased weight (19%, P < 0.05) compared with control pigs. Overall, dietary supplementation of betaine + CLA increased ADG, protein, water, and lean deposition in growing Iberian gilts. There appears to be a synergistic action when betaine and CLA are used together.     

Growth performance, diet apparent digestibility, and plasma metabolite concentrations of barrows fed corn-soybean meal diets or low-protein, amino acid-supplemented diets at different feeding level

Two experiments, each with 36 barrows with high-lean-gain potential, were conducted to evaluate apparent nutrient digestibilities and performance and plasma metabolites of pigs fed corn-soybean meal diets (CONTROL) and low-protein diets. The low-protein diets were supplemented with crystalline lysine, threonine, tryptophan, and methionine either on an ideal protein basis (IDEAL) or in a pattern similar to that of the control diet (AACON). Amino acids were added on a true ileally digestible basis. The initial and final BW were, respectively, 31.5 and 82.3 kg in Exp. 1 and 32.7 and 57.1 kg in Exp. 2. In Exp. 1, the CONTROL and IDEAL diets were offered on an ad libitum basis or by feeding 90 or 80% of ad libitum intake. Pigs were fed for 55 d. In Exp. 2, the CONTROL, IDEAL, and AACON diets were offered on an ad libitum basis or by feeding 80% of the ad libitum intake. Pigs were fed for 27 d. Pigs fed the CONTROL diet had greater (P < 0.05) ADG and feed efficiency (G/F) than pigs fed the IDEAL (Exp. 1 and 2) and AACON diets (Exp. 2). As the level of feed intake decreased, ADG decreased (P < 0.05), but G/F tended to improve (P < 0.10) for pigs fed 90% of ad libitum in Exp. 1 and for pigs fed 80% of ad libitum in Exp. 2. In Exp. 1, the apparent total tract digestibilities of DM and energy were greater (P < 0.01) for pigs fed the IDEAL diet than for pigs fed the CONTROL diet. In Exp. 2, the apparent total tract digestibility of protein was greatest in pigs fed the CONTROL diet (P < 0.05) and was greater (P < 0.05) in pigs fed the AACON diet than in pigs fed the IDEAL diet. Plasma urea concentrations were lower in pigs fed the IDEAL diet than in pigs fed the CONTROL diet, regardless of feeding level. For pigs fed the CONTROL diet, plasma urea concentrations were lower when feed intake was 80% of ad libitum (diet level, P < 0.01). In summary, pigs fed the IDEAL and the AACON diets gained less and had lower plasma urea concentrations than pigs fed the CONTROL diet. Based on these data, it seems that the growth potential of pigs fed the IDEAL and AACON diets may have been limited by a deficiency of lysine, threonine, and(or) tryptophan and that the amino acid pattern(s) used was not ideal for these pigs.     

Glycemic index of starch affects nitrogen retention in grower pigs

Three studies were performed to examine the effect of starch and protein digestion rates on N retention in grower pigs. In Exp. 1, the glycemic index (GI) of corn, a malting barley, and a slow-rumen-degradable barley (SRD-barley) were measured using 6 barrows (BW = 18.0 ± 0.5 kg). The GI of malting barley was greater (P < 0.05) than that of SRD-barley (71.1 vs. 49.4), and the GI of both barley cultivars was less (P < 0.05) than that of corn (104.8). In Exp. 2, the standardized ileal digestibility of AA and DE content of the 3 ingredients were determined using 5 ileal-cannulated barrows (BW = 20.7 ± 2.3). The apparent total-tract energy digestibility values of corn (86.1%) and malting barley (85.7%) were greater (P < 0.05) than that of SRD-barley (82.3%). The standardized ileal digestibility of Lys was 94.0, 92.6, and 92.4% for corn, malting barley, and SRD-barley, respectively, and did not differ among grains. In Exp. 3, 6 diets were formulated to equal DE (3.40 Mcal/kg), standardized ileal digestibility of Lys (8.6 g/kg), starch (424.9 g/kg), and digestible CP (180.0 g/kg) using the values obtained in Exp. 2. Three GI [high (corn), medium (malting barley), and low (SRD-barley)] and 2 rates of protein digestion [rapid (soy protein hydrolysate) and slow (soy protein isolate)] were tested in a 3 × 2 factorial arrangement with 36 barrows (BW = 32.2 ± 2.5 kg). Pigs were fed 3.0 times the maintenance energy requirement daily in 2 meals for 2 wk and were housed in metabolic crates to collect feces and urine separately. At the end of the study, intestinal contents were collected from 4 equal-length segments of the small intestine. The percentage of unabsorbed CP in segment 1 relative to dietary CP was greater (P < 0.05) for the soy protein isolate diet than for the soy protein hydrolysate diet (170.3 vs. 116.5%). The percentages of unabsorbed starch in segments 1 and 2 were greater (P < 0.05) for the SRD-barley diet than for the malting barley or corn diet. Nitrogen intake and fecal N excretion were greater (P < 0.05) for pigs fed the malting barley and SRD-barley diets than for pigs fed the corn diet. Urinary N excretion was greater (P < 0.05) for pigs fed the SRD-barley diet than for pigs fed the corn or malting barley diet. Pigs fed slowly digestible starch (SRD-barley; 46.6%) had less (P < 0.05) net N retention than pigs fed corn or malting barley (54.7 and 54.1%, respectively). In conclusion, slowly digestible starch sources such as SRD-barley may not be suitable to support maximum protein deposition in restricted-fed grower pigs.     

Comparison of grain sources for swine diets and their effect on meat and fat quality traits

A study was conducted to evaluate the effect of dietary grain sources on various compositional and quality characteristics of pork from pigs reared in a commercial environment. Pigs were fed 1 of 5 dietary treatments containing the following single or blended grain sources throughout most of the grow-finish period: 1) yellow corn, 2) white corn, 3) 1/3 yellow corn and 2/3 white corn, 4) 2/3 yellow corn and 1/3 white corn, and 5) barley. Pigs were from 2 sire genetic types, Duroc and Hampshire x Duroc, mated to PIC 1055 females. A total of 1,040 pigs were included in the study in a 2 x 2 x 5 factorial arrangement with 2 genetic types, 2 sexes (barrows and gilts), and 5 dietary treatments. Eight pigs were randomly selected from each pen of 26 (n = 320) for meat and fat quality evaluation. Pigs were 27.6 kg at the beginning of the experiment and were fed to 130.2 kg. All animals were held overnight at a commercial abattoir before slaughter. One whole, skin-on, boneless loin was collected from each carcass and held at -1 degrees C in a cryovac-sealed bag at the Iowa State University Meat Laboratory. At 25 to 27 d postslaughter, loins were evaluated for meat and fat quality. Dietary treatment had no effect (P > 0.05) on 24-h pH, sensory tenderness, sensory chewiness, Instron tenderness, loin purge, or cook loss. At 25 to 27 d postslaughter, pigs fed diet 4 had a greater (P < 0.05) loin pH than pigs fed diet 1, and diets 2, 3, and 5 were not different from all treatment means. Pigs fed diet 4 had a greater (P < 0.05) Japanese color score than pigs fed diets 2, 3, and 5, and diet 1 was not different from all treatment means. Pigs fed diet 3 had a greater percentage of intramuscular fat than pigs fed diets 1 and 2, although diets 1, 4, and 5 and diets 1, 2, and 5 were not different (P > 0.05). No differences among dietary treatments were found for fat color values on a subjective basis. Pigs fed diet 5 had a more desirable objective fat color than pigs fed all white corn, and diets 1, 3, and 4 were not different (P > 0.05). Pigs fed diet 5 had greater levels of SFA and MUFA, and lower levels of unsaturated fatty acids and PUFA, in the subcutaneous fat than pigs fed all other diets. These results indicate that the energy sources evaluated in this study had little effect on eating quality of pork that was held for 25 to 27 d postslaughter.     

Effect of irradiation of individual feed ingredients and the complete diet on nursery pig performance

A total of 1,210 nursery pigs was used in two experiments to evaluate the effects of irradiation of typical nursery diet ingredients, specialty protein products, and the whole diet on nursery pig performance. In Exp. 1, 880 barrows and gilts (15 +/- 2 d of age at weaning) were used in two growth trials (14 d and 12 d for Trials 1 and 2, respectively) to determine the effects of individual ingredient and whole-diet irradiation on nursery pig performance. Overall (d 0 to 14 of Trial 1 and d 0 to 12 of Trial 2), ADG was greater (P < 0.05) for pigs fed irradiated animal plasma compared with pigs fed the control, the diet containing irradiated microingredients, and the diet that was manufactured and irradiated. Also, pigs fed irradiated soybean meal had greater (P < 0.05) ADFI compared with pigs fed the manufactured diet that was irradiated. Pigs fed the diet containing irradiated animal plasma had improved feed efficiency (G:F; P < 0.05) compared with those fed the diet with irradiated microingredients and when all ingredients were irradiated before manufacturing of complete feed. Finally, pigs fed irradiated corn, whey, fishmeal, soybean oil, microingredients, or if all ingredients or the whole diet were irradiated, had similar ADG, ADFI, and G:F (P > 0.12) to control pigs. In Exp. 2, 330 nursery pigs (20 +/- 2 d of age at weaning) were used to determine the effects of irradiation of commercially available specialty protein products in diets for nursery pigs. Overall, ADG was greater (P < 0.05) when pigs were fed diets containing nonirradiated spray-dried animal plasma and egg combination (SDAPE) and dried porcine digest (DPD) compared with pigs fed the control diet containing no specialty protein products. In addition, G:F was improved (P < 0.05) when pigs were fed diets containing nonirradiated SDAPE, DPD, spray-dried beef muscle (SDBM), and spray-dried whole egg (SDWE) compared with pigs fed the control diet. Pigs fed irradiated SDAPE and SDBM had greater (P < 0.05) ADG than pigs fed the nonirradiated forms. Pigs fed irradiated SDBM had improved (P < 0.05) G:F compared with pigs fed the nonirradiated form. In Exp. 1 and 2, an irradiation treatment level of 8.5 kGy was effective in reducing the total bacterial concentration of all ingredients evaluated, as well as the whole diet in Exp.1. Irradiation of certain ingredients, but not the complete diet, increased growth performance of nursery pigs.     

Performance of growing-finishing pigs fed diets containing YieldGard Rootworm corn (MON 863), a nontransgenic genetically similar corn, or conventional corn hybrids

Two studies were conducted at two locations to evaluate growth performance and carcass characteristics of growing-finishing pigs fed diets containing either YieldGard Rootworm corn (MON 863), a non-transgenic genetically similar corn (RX670), or two conventional nontransgenic corn hybrids (DK647 and RX740). A randomized complete block design with a 2 x 4 factorial arrangement of treatments (two genders and four corn hybrids) was used. Study 1 used 72 barrows and 72 gilts (progeny of Danbred sires x [Danbred x NE White line] dams grown from 22.7 to 117.0 kg BW). Pigs were housed in a modified open-front building in single-gender groups of six (six pens per dietary treatment). Study 2 used 80 barrows and 80 gilts (progeny of PIC 337 sires x C22 dams) grown from 29.5 to 114.9 kg BW. Pigs were housed in an environmentally controlled finishing building in single-gender groups of five (eight pens per dietary treatment). The test corns were included at a fixed proportion of the diet in both studies. Animals had ad libitum access to feed and water. Pigs were slaughtered at the end of the growth period using standard procedures, and carcass measurements were taken. There were no diet x gender interactions for growth performance or carcass measurements in either study. In both studies, overall ADG, ADFI, and G:F were not affected by corn hybrid. There was no effect of corn hybrid on carcass or LM quality measurements in Study 1. In Study 2, LM protein content was less (P< 0.05) for pigs fed RX740 compared with those fed either MON 863 or RX670; however, there was no effect of corn hybrid on other LM composition measures or on quality traits. In both studies, differences between barrows and gilts for growth and carcass traits were similar to previous research. These results suggest that the YieldGard Rootworm corn (MON 863) results in equivalent growth performance and carcass quality to nontransgenic corn hybrids in growing-finishing pigs.     

Effect of trimethylamine oxide and betaine in swine diets on growth performance, carcass characteristics, nutrient digestibility, and sensory quality of pork.

Two growth experiments and one digestibility experiment were conducted to study the effect of trimethylamine oxide (TMAO) and betaine in swine diets. In Exp. 1, 36 limit-fed pigs averaging 19.1 kg in initial weight were used to study the effect of adding TMAO at 10 g/kg of feed or betaine at an equivalent level of methyl groups (10.5 g/kg feed) to a high-fat (11.3% ether extract) basal diet. Dietary addition of TMAO increased ADG by 61 g/d, reduced number of days to market by 8.3 d (P<.02), and tended (P<.09) to improve gain/feed (G/F) compared with the control diet. Betaine had no effect on growth performance of pigs. Adding TMAO or betaine to diets had no effect on percent carcass fat, percent carcass lean, or dressing percentage. Dietary supplementation of TMAO reduced (P<.05) plasma triacylglycerol level (TAG) compared with the control diet. There was no effect of dietary TMAO or betaine on sensory quality characteristics of pork. In Exp. 2, 48 ad libitum-fed pigs averaging 21.7 kg initial BW and 104.7 kg final BW were used to determine the effect of adding low and intermediate levels of TMAO (1, 2, or 5 g/kg) to diets. Adding 1 g of TMAO increased G/F (P<.01) compared with control pigs. When using orthogonal contrasts, adding 2 g of TMAO reduced (P<.05) P2 backfat thickness and tended to increase (P<.09) lean percentage compared with the control diet. Trimethylamine oxide gave a quadratic effect (P<.05) on plasma TAG levels. Adding 1 and 2 g of TMAO increased plasma TAG, but 5 g of TMAO decreased it compared with the control diet. In Exp. 3, 12 barrows of 42.3 kg average initial BW and 50.0 kg final BW were used to investigate the effect of supplementing diets with 1 g of TMAO and 1.27 g of betaine/kg of feed on apparent total tract nutrient digestibility. The addition of TMAO increased (P<0.03) apparent total tract digestibility of fat (HCl-EE). Betaine had no such effect. Adding TMAO to diets influenced growth performance and carcass quality in a dose-dependent manner.