Effects of dietary supplementation of formaldehyde and crystalline amino acids on gut microbial composition of nursery pigs.

Formaldehyde-based feed additives are approved in the US for Salmonella control and reducing bacterial contamination in animal feed. However, we hypothesize formaldehyde inclusion in swine diets may influence gut microbial composition due to its antimicrobial properties which might negatively influence microbial populations and pig growth performance. Also, formaldehyde inclusion in diets is known to reduce the dietary availability of amino acids. Therefore, our study was conducted to characterize if the effects of feed formaldehyde-treatment are due to influences on microbial population or diet amino acid (AA) sources. Dietary treatments were arranged in a (2 × 2) + 1 factorial with formaldehyde treatment (none vs. 1000 ppm formaldehyde) and crystalline AA inclusion (low vs. high) with deficient AA content plus a positive control diet to contain adequate AA content without dietary formaldehyde. Treating diets with formaldehyde reduced growth rate (P = 0.001) while the AA inclusion had no evidence of impact. Formaldehyde reduced feed bacterial content and altered fecal microbial communities (P < 0.05). Therefore, we conclude that the negative influence on growth was due to the impact on the fecal microbial community. Implications are that strategies for feed pathogen control need to take into account potential negative impacts on the gut microbial community.

The effects of copper source and concentration on growth performance, carcass characteristics, and pen cleanliness in finishing pigs.

A total of 1,143 pigs (PIC 337 × 1050, initially 25.1 ± 0.03 kg BW) were used in a 111-d study to determine the effects of copper sulfate (CuSO; Prince Agri-Products, Quincy, IL) or tribasic copper chloride (TBCC; IntelliBond C; Micronutrients, Indianapolis, IN) on growth performance, carcass characteristics, and pen cleanliness. Pens of pigs were allotted to 1 of 6 dietary treatments, balanced on average pen weight in a randomized complete block design with 25 to 28 pigs per pen and 7 replications per treatment. Treatments included a corn-soybean meal-based diet (corn-soy), a high-by-product diet with 30% distillers dried grains with solubles and 15% bakery meal (by-product diet), and the by-product diet with 75 or 150 mg/kg added Cu from CuSO or TBCC. All diets contained 20 mg/kg Cu from CuSO in the trace mineral premix. At the conclusion of the trial, a digital photo of each pen was taken to allow 3 independent observers to score manure texture and buildup and to assess pen cleanliness prior to power washing. Furthermore, the time required to power wash each pen was also measured. Overall, pigs fed the by-product diet tended to have increased ADFI ( = 0.083) and had decreased G:F ( = 0.005) compared to those fed the corn-soy diet. No Cu source × level interactions or Cu source differences were observed ( > 0.05). From d 0 to 71, pigs fed increasing Cu had increased (quadratic, < 0.05) ADG, d 71 BW, and ADFI. From d 71 to 111, pigs fed increasing Cu tended to have increased ADFI (linear, = 0.068) and decreased G:F (quadratic, = 0.056). Overall (d 0 to 111), increasing Cu increased (linear, < 0.01) ADG, final BW, and ADFI (quadratic, = 0.026). Hot carcass weight increased (linear, = 0.023) by 2.4 kg with increasing Cu. Increasing Cu also increased loin depth (linear, = 0.019) and percentage lean (quadratic, = 0.024). Manure buildup and wash time (s/pen) increased ( < 0.05) for by-product diet pens compared to corn-soy pens; however, neither wash time nor pen cleanliness were influenced by added Cu. In summary, increasing dietary Cu in high-by-product diets improved growth and feed intake, resulting in increased final BW and HCW for pigs fed both Cu sources, without influencing pen wash time.

Effects of distillers dried grains with solubles and added fat fed immediately before slaughter on growth performance and carcass characteristics of finishing pigs.

The addition of dietary fat has been shown to increase HCW and carcass yield in pigs fed low-fiber corn-soy diets; however, data on added fat in high-fiber, low-energy diets is less available. Therefore, the potential for dietary fat to ameliorate the negative effect high-fiber diets have on carcass yield during the last 3 wk before slaughter is of high importance. This experiment was conducted to determine the interactive effects of 30% distillers dried grains with solubles (DDGS) and 5% added fat fed before slaughter on growth performance and carcass characteristics. A total of 1,258 pigs in 2 groups (initially 105.8 ± 0.1 kg BW; group 1 PIC 337 × 1,050; group 2 PIC 327 × 1,050) were used in a 20-d experiment. All pigs were fed a common diet with 30% DDGS until 20 d before slaughter. Then, all pens were weighed and allotted to treatments with 20 replicate pens per treatment. Dietary treatments were arranged in a 2 × 2 factorial with 2 diet types (corn-soybean meal-based with or without 30% DDGS) and added fat (0 or 5%; group 1 = tallow; group 2 = choice white grease). Diets were formulated to a constant standardized ileal digestible Lys:NE ratio. There were no treatment × group interactions for any response criteria. Thus, data for the 2 groups were combined for analysis. Overall, there was a tendency for a diet type × added fat interaction for ADG ( = 0.054), whereas this was significant for G:F ( = 0.008). This was a result of 5% added fat increasing ADG and G:F to a greater magnitude for pigs fed the diet containing 30% DDGS (8.6 and 10.4%, respectively) than for pigs fed the corn-soy diet (2.0 and 2.9%, respectively). Although diet type did not affect final live BW, pigs fed the diet containing DDGS had decreased HCW and carcass yield ( < 0.05). Adding 5% fat did not affect carcass yield. In conclusion, adding 5% fat to finishing pig diets containing 30% DDGS approximately 20 d before slaughter improved ADG and G:F but did not overcome the reduction in carcass yield from feeding DDGS.

Evaluating the impact of maternal vitamin D supplementation: I. Sow performance, serum vitamin metabolites, and neonatal muscle characteristics.

In Exp. 1, 56 gestating sows (PIC 1050; 35 d postinsemination) were used in a 30-d trial to determine serum 25(OH)D response to increasing concentrations of dietary vitamin D. Sows were randomly allotted to 1 of 7 dietary D treatments (200, 800, 1,600, 3,200, 6,400, 12,800, or 25,600 IU of added D per kilogram of complete diet) with 8 sows per treatment. Increasing D increased (quadratic; < 0.001) serum 25(OH)D with the response depicted by the prediction equation: serum 25(OH)D, ng/mL = 35.1746 + (0.002353 × dietary D, IU/d) - (0.0000000156 × dietary D, IU/d). In Exp. 2, 112 sows and their litters were used to determine the effects of dietary vitamin D regimen on sow performance, subsequent preweaning pig performance, neonatal bone and muscle characteristics, and serum vitamin metabolites. Sows were allotted to 1 of 4 dietary treatments 3 to 5 d following breeding: 800, 2,000, or 9,600 IU of D per kilogram of the diet or 50 µg of 25(OH)D (2,000 IU of D equivalent from Hy-D, DSM Nutritional Products, Parsippany, NJ) per kilogram of diet. There were 25 to 27 sows per treatment. Increasing dietary D increased (linear, = 0.001) serum 25(OH)D of sows on d 100 of gestation, at farrowing, and at weaning. Increasing D in sow diets increased piglet serum 25(OH)D at birth (linear, = 0.001) and weaning (quadratic, = 0.033). Sows fed 50 µg of 25(OH)D/kg had intermediate ( < 0.004) serum 25(OH)D concentrations on d 100 of gestation, at farrowing, and at weaning compared with sows fed 2,000 IU of D/kg and sows fed 9,600 IU of D/kg. Pigs from sows fed 50 µg of 25(OH)D/kg had greater serum 25(OH)D compared with pigs from sows fed 2,000 IU of D/kg, but at weaning, serum 25(OH)D concentrations were similar. Also, pigs from sows fed 9,600 IU of D/kg had greater ( = 0.011) serum 25(OH)D at birth and weaning compared with pigs from sows fed 50 µg of 25(OH)D/kg. Maternal performance, litter characteristics, neonatal bone ash content, and neonatal muscle fiber characteristics were largely unaffected by the dietary vitamin D treatments. Overall, D and 25(OH)D are both useful at increasing serum 25(OH)D concentrations, but more D (on an equivalent IU basis) is needed to achieve similar serum 25(OH)D responses compared with feeding 25(OH)D. Concentration of maternal vitamin D supplementation in lactation impacted milk transfer of the vitamin more so than the form of the vitamin, as evidence by the weaned pig serum 25(OH)D concentrations.

Evaluating the impact of maternal vitamin D supplementation on sow performance: II. Subsequent growth performance and carcass characteristics of growing pigs.

A of subsample of 448 growing pigs (PIC 327 × 1050) weaned from 52 sows fed varying dietary vitamin D regimens were used in a split-plot design to determine the effects of maternal and nursery dietary vitamin D on growth performance. Sows were previously administered diets containing vitamin D as vitamin D (800, 2,000, or 9,600 IU/kg) or as 25(OH)D (50 µg [or 2,000 IU vitamin D equivalent]/kg from HyD; DSM Nutritional Products, Parsippany, NJ). Once weaned, pigs were allotted to pens on the basis of previous maternal vitamin D treatment, and then pens were randomly assigned to 1 of 2 nursery vitamin D dietary regimens (2,000 IU of vitamin D/kg or 50 µg 25(OH)D/kg). Pigs remained on nursery vitamin D treatments for 35 d, and then they were provided common finishing diets until market (135 kg). Growing pig serum 25(OH)D suggested that maternal dietary vitamin D influenced ( < 0.001 at weaning) serum concentrations early after weaning, but nursery vitamin D regimen had a larger impact ( < 0.001) on d 17 and 35 postweaning. Overall growth performance was not influenced by nursery vitamin D dietary treatments. From d 0 to 35 in the nursery, pigs from sows fed increasing vitamin D had increased (quadratic, < 0.003) ADG and ADFI, but G:F was similar regardless of maternal vitamin D regimen. Also, pigs from sows fed 50 µg/kg of 25(OH)D had increased ( = 0.002) ADG compared with pigs weaned from sows fed 800 IU of vitamin D. Throughout finishing (d 35 postweaning until 135 kg), ADG was increased (quadratic, = 0.005) and G:F was improved (quadratic, = 0.049) with increasing maternal dietary vitamin D. Also, pigs from sows fed 50 µg/kg of 25(OH)D had increased ( = 0.002) ADG compared with pigs weaned from sows fed 800 IU of vitamin D. Carcass data were collected from a subsample population separate from that used for the growth performance portion of the study, and a total of 642 carcasses from progeny of sows fed the varying dietary vitamin D treatments were used. Live BW of pigs at marketing and HCW were heavier ( < 0.030) for pigs from sows previously fed 25(OH)D compared with pigs from sows fed 9,600 IU of vitamin D. Overall, pigs from sows fed 2,000 IU of vitamin D grew faster after weaning compared with pigs from sows fed 800 or 9,600 IU of vitamin D. Pigs from sows fed 25(OH)D hag greater ADG compared with pigs from sows fed 800 IU of vitamin D, and they had increased final BW and HCW compared with pigs from sows fed 9,600 IU of vitamin D.

Effects of dietary copper, zinc, and ractopamine hydrochloride on finishing pig growth performance, carcass characteristics, and antimicrobial susceptibility of enteric bacteria.

A total of 480 pigs (PIC 327 × 1050; initially 48.7 ± 2.3 kg) were used to determine the interactive effects of supplemental Cu, Zn, and ractopamine HCl (RAC) on finishing pig growth performance, carcass characteristics, and antimicrobial susceptibility of enteric bacteria. Treatments were arranged in a 2 × 2 × 2 factorial with the main effects of added Cu (CuSO; 0 vs. 125 mg/kg Cu), Zn (ZnO; 0 vs. 150 mg/kg Zn), and RAC (0 vs. 10 mg/kg during the last 28 d prior to marketing). All diets contained 11 mg/kg Cu and 73 mg/kg Zn from the trace mineral premix. Pens of pigs were balanced and blocked on initial BW and then randomly allotted to 1 of the 4 mineral treatment diets. At 28 d prior to marketing, pens within each block and mineral treatment were randomly assigned to receive either 0 or 10 mg/kg RAC in addition to the mineral treatment. Adding either Cu or Zn alone did not improve ADG or ADFI yet resulted in numerical improvements in overall G:F and caloric efficiencies, but improvements were not additive (Cu × Zn, = 0.057, = 0.068, and = 0.064 for G:F and caloric efficiency on a ME and NE basis, respectively). Ractopamine improved ( < 0.001) overall ADG, G:F, and caloric efficiency, thereby increasing final BW by 3% with no change in ADFI. Ractopamine also increased ( < 0.001) HCW, percentage carcass yield, G:F, loin depth, and percent fat-free lean and decreased ( = 0.014) backfat. Adding Zn or Cu alone to diets containing RAC numerically improved percent yield and HCW G:F, but this effect was absent when the Cu or Zn was added to the control diet or when Cu and Zn were fed in combination in RAC diets (Cu × Zn × RAC, = 0.011 and = 0.018 for yield and HCW G:F, respectively). Fecal samples were collected on d 0 and at the conclusion of the finishing period (d 90) for bacterial isolation and antimicrobial susceptibility determinations according to Clinical and Laboratory Standards Institute minimal inhibitory concentrations breakpoints. spp. and isolates displayed varying levels of resistance to certain antibiotics prior to initiation of treatments on d 0. Resistance to most antibiotics decreased ( < 0.05) over time or was stable for those that had a low baseline percentage of resistance. Neither Zn nor RAC adversely affected antimicrobial resistance. However, extended feeding of 125 mg/kg Cu throughout the finishing period seems to decrease enterococcal susceptability to tetracycline, tylosin, and quinupristin/dalfopristin.

Influence of dietary fat source and feeding duration on finishing pig growth performance, carcass composition, and fat quality.

A total of 160 finishing pigs (PIC 327 × 1050; initially 45.6 kg) were used in an 84-d experiment to evaluate the effects of dietary fat source and feeding duration on growth performance, carcass characteristics, and carcass fat quality. There were 2 pigs per pen with 8 pens per treatment. The 10 dietary treatments were a corn-soybean meal control diet with no added fat and a 3 × 3 factorial with main effects of fat source (4% tallow, 4% soybean oil, or a blend of 2% tallow and 2% soybean oil) and feeding duration (d 0 to 42, 42 to 84, or 0 to 84). The control corn-soybean meal diet was fed in place of added fat diets when needed for duration treatment purposes. On d 0, 1 pig was identified in each pen and fat biopsy samples of the back, belly, and jowl were collected on d 0, 41, and 81 for fatty acid analysis. At the conclusion of the study, all pigs were harvested, carcass characteristics were determined, and back, belly, and jowl fat samples were collected for analysis. Overall (d 0 to 84), there were no differences among pigs fed the different fat sources for growth and carcass characteristics; however, pigs fed diets with added fat for the entire study had improved ( = 0.036) G:F compared with pigs fed the control diet without added fat. Pigs fed supplemental fat throughout the entire study also had improved ( < 0.05) ADG and G:F as well as heavier d-84 BW ( = 0.006) compared with pigs fed additional fat during only 1 period. Adding fat for the entire study increased ( = 0.032) backfat and tended to reduce ( = 0.079) the fat free lean index compared with pigs fed the control diet without added fat. Added fat also increased ( < 0.05) the iodine value (IV) when compared with pigs fed the control diet. Increasing the feeding duration of soybean oil lowered MUFA and increased PUFA concentrations for all fat depots, whereas these values remained relatively unchanged by the addition of tallow (duration × fat source interactions, < 0.05). Our study failed to show any feeding period × fat source interactions ( < 0.05) in fatty acid composition or IV for jowl fat, whereas this interaction occurred for belly fat and backfat, which would indicate a longer turnover rate for jowl fat. In conclusion, feeding additional fat improved ADG and G:F; however, feeding soybean oil for an increased duration, either alone or in combination with tallow, negatively affected the fatty acid composition and IV of different fat depots.

Effects of Added Zinc on Skeletal Muscle Morphometrics and Gene Expression of Finishing Pigs Fed Ractopamine-HCL.

Finishing pigs (n = 320) were used in a 35-day study to determine the effects of ractopamine-HCl (RAC) and supplemental Zinc (Zn) level on loin eye area (LEA) and gene expression. Pens were randomly allotted to the following treatments for the final 35 days on feed: a corn-soybean meal diet (CON), a diet with 10 ppm RAC (RAC+), and RAC diet plus added Zn at 75, 150, or 225 ppm. Sixteen pigs per treatment were randomly selected for collection of serial muscle biopsies and carcass data on day 0, 8, 18, and 32 of the treatment phase. Compared to CON carcasses, RAC+ carcasses had 12.6% larger (P = 0.03) LEA. Carcasses from RAC diets with added Zn had a tendency for increased (quadratic, P < 0.10) LEA compared to the RAC+ carcasses. Compared to RAC+ pigs, relative expression of IGF1 decreased with increasing levels of Zn on day 8 and 18 of treatment, but expression levels were similar on day 32 due to Zn treatments increasing in expression while the RAC+ treatment decreased (Zn quadratic × day quadratic, P = 0.04). A similar trend was detected for the expression of ß1-receptor where expression levels in the RAC+ pigs were greater than Zn supplemented pigs on day 8 and 18 of the experiment, but the magnitude of difference between the treatments was reduced on day 32 due to a decrease in expression by RAC+ pigs and an increase in expression by the Zn pigs (Zn quadratic × day quadratic, P = 0.01). The ability of Zn to prolong the expression of these two genes may be responsible for the tendency of Zn to increase LEA in RAC supplemented pigs.

Effects of diet form and type on growth performance, carcass yield, and iodine value of finishing pigs.

Two experiments were conducted to determine the effects of pelleting, diet type (fat and fiber level), and withdrawal of dietary fiber and fat before marketing on growth performance, carcass yield, and carcass fat iodine value (IV) of finishing pigs. Each experiment used 288 pigs (initially 49.6 and 48.5 kg BW, respectively) with 6 dietary treatments arranged as 2 × 3 factorials. In Exp. 1, main effects were diet form (meal vs. pellet) and diet regimen. Diet regimens were 1) a low-fiber, low-fat (corn-soybean meal) diet from d 0 to 81, 2) a high-fiber, high-fat (30% dried distillers grains with solubles [DDGS] and 19% wheat middlings [midds]) diet from d 0 to 64 followed by the low-fiber, low-fat diet from d 64 to 81 (fiber and fat withdrawal), and 3) the high-fiber, high-fat diet fed from d 0 to 81. Pigs fed pelleted diets had increased ( < 0.05) ADG and G:F compared with those fed meal diets. Pigs fed pelleted diets had increased belly fat IV (2.9 mg/g) compared with those fed meal diets, with a greater increase when fed high-fiber, high-fat diets throughout the entire study (interaction, < 0.05). Pigs fed the low-fiber, low-fat diet throughout had increased ( < 0.001) G:F compared with pigs fed the other 2 treatments. Pigs fed low-fiber, low-fat diets throughout the study or pigs withdrawn from high-fiber, high-fat diets had increased ( < 0.001) carcass yield compared with pigs fed high-fiber, high-fat diets throughout. In Exp. 2, treatment main effects were diet form (meal vs. pellet) and diet type (corn-soybean meal-based control, the control with 30% DDGS and 19% midds, or the control diet with 3% corn oil). The diet containing corn oil was calculated to produce carcass fat IV similar to diets containing DDGS and midds. Overall, pigs fed pelleted diets had increased ( < 0.05) ADG, G:F, and belly fat IV (1.3 mg/g) compared with those fed meal diets. Pigs fed the diets containing DDGS and midds had decreased ( < 0.05) ADG, carcass yield, and HCW compared with pigs fed the control or corn oil diets and decreased ( < 0.001) G:F compared with pigs fed added corn oil. Belly IV was greatest ( < 0.001) for pigs fed diets with DDGS and midds and lowest for pigs fed the control diet, with pigs fed the corn oil diets intermediate. In conclusion, pelleting diets improves pig ADG (approximately 3%) and G:F (approximately 6%); however, a novel finding of this study is that pelleting diets fed to finishing pigs also increases belly fat IV.

Effect of added zinc in diets with ractopamine hydrochloride on growth performance, carcass characteristics, and ileal mucosal inflammation mRNA expression of finishing pigs.

Two experiments were conducted to determine the effects of increasing the dietary Zn content on growth performance, carcass characteristics, plasma Zn, and ileal mucosal inflammation mRNA expression of finishing pigs fed diets containing ractopamine HCl (RAC; Elanco Animal Health, Greenfield, IN). In Exp. 1, 312 pigs (327 × 1050; PIC, Hendersonville, TN; 94 kg BW) were used in a 27-d study. There were 2 pigs per pen and 26 pens per treatment. Treatments included a corn-soybean meal diet (control; 0.66% standardized ileal digestible [SID] Lys); a diet (0.92% SID Lys) with 10 mg/kg RAC; and the RAC diet plus 50, 100, or 150 mg Zn/kg from ZnO or 50 mg Zn/kg from a Zn AA complex (ZnAA; Availa-Zn; Zinpro, Eden Prairie, MN). All diets also contained 83 mg Zn/kg from ZnSO4 in the trace mineral premix. Pigs fed the RAC diet without added Zn had increased (P < 0.05) ADG, G:F, HCW, carcass yield, and loin weight compared with pigs fed the control diet. Increasing Zn from ZnO in diets containing RAC tended to increase (linear, P = 0.067) G:F and loin weight (quadratic, P = 0.064). Pigs fed diets with 50 mg Zn/kg from ZnAA tended to have increased (P = 0.057) ADG compared with pigs fed the RAC diet. In Exp. 2, 320 pigs (327 × 1050; PIC; 98 kg BW) were used in a 35-d study. There were 2 pigs per pen and 20 pens per treatment. Treatments included a control diet (0.66% SID Lys); a diet (0.92% SID Lys) with 10 mg/kg RAC; or the RAC diet plus 75, 150, and 225 mg Zn/kg from ZnO or ZnAA. All diets also contained 55 mg Zn/kg from ZnSO4 from the trace mineral premix. Pigs fed the RAC diet had increased (P < 0.05) ADG, G:F, HCW, loin depth, percentage lean, and liver weight compared with pigs fed the control diet. No Zn level or source effects or level × source interactions were observed for growth performance. A Zn level × source interaction (quadratic, P = 0.007) was observed in liver Zn concentrations. This resulted from liver Zn concentrations plateauing at 150 mg Zn/kg when ZnO was supplemented, while there was a linear increase when using ZnAA. Increasing Zn in diets containing RAC increased (linear, P < 0.05) plasma Zn on d 18 and 32. The expression of IL-1ß was increased (P = 0.014) in mucosa of pigs fed the RAC diet compared with those fed the control diet. Expression of IL-1ß decreased (linear, P = 0.026) in the mucosa of pigs fed increasing added Zn. In conclusion, adding Zn to diets containing RAC resulted in a trend for improved growth performance of pigs in 1 of 2 experiments. Also, additional Zn increased plasma Zn and reduced IL-1ß.

Effects of dietary vitamin E concentration and source on sow, milk, and pig concentrations of α-tocopherol.

A total of 126 gilts and sows (PIC 1050) and their litters were used to determine the effects of dietary vitamin E concentration and source on sow plasma, milk, and pig concentrations of α-tocopherol. Additionally, we estimated the bioavailability of D-α-tocopheryl acetate (D-α-TAc) relative to DL-α-tocopheryl acetate (DL-α-TAc) when fed in diets containing dried distillers grains with solubles (DDGS). The 6 dietary treatments included DL-α-TAc at 44 and 66 mg/kg and D-α-TAc at 11, 22, 33, and 44 mg/kg. From breeding to d 69 of gestation, sows were fed 2.0 kg/d of a diet containing 40% DDGS, 0.30 mg/kg added Se, and no added vitamin E. Vitamin E treatments were fed from d 70 of gestation through weaning. Plasma was collected from sows on d 69 and 100 of gestation, at farrowing, and at weaning. Colostrum and milk samples were also collected. Plasma from 3 pigs per litter and heart and liver samples from 1 pig per litter were collected at weaning. Plasma, milk, and tissues from 6 litters per treatment were analyzed for α-tocopherol. Although tissue, plasma, and milk concentrations of α-tocopherol were the primary response criteria of interest, sow and litter performance were measured. As expected, treatment effects were not observed for lactation feed intake, sow BW, or backfat measurements. A trend (P = 0.085) for a treatment effect on average pig BW at weaning was detected, with pigs nursing sows fed 44 mg/kg DL-α-TAc weighing less because of a younger weaning age. No other differences in litter performance were observed. As D-α-TAc increased in the diet, sow plasma, colostrum, and milk, pig plasma, and pig heart concentrations of α-tocopherol increased (linear, P < 0.03). Sows fed diets with 44 mg/kg D-α-TAc had increased (P < 0.03) plasma and colostrum and pig plasma concentrations of α-tocopherol compared with sows fed 44 mg/kg of DL-α-TAc. Sows fed 66 mg/kg DL-α-TAc also had greater (P = 0.022) plasma α-tocopherol at weaning than sows fed 44 mg/kg DL-α-TAc. Bioavailability coefficients for D-α-TAc relative to DL-α-TAc ranged from 1.9 to 4.2 for sow and pig plasma α-tocopherol, 2.9 to 3.6 for colostrum α-tocopherol, 1.6 for milk α-tocopherol, and 1.7 to 2.0 for pig heart and liver α-tocopherol. Overall, this study indicates the bioavailability for D-α-TAc relative to DL-α-TAc varies depending on the response criteria but is greater than the standard potency value of 1.36.

Effects of dietary wheat middlings, corn dried distillers grains with solubles, and net energy formulation on nursery pig performance.

Four experiments were conducted to examine effects of dietary wheat middlings (midds), corn dried distillers grains with solubles (DDGS), and NE formulation on nursery pig performance and caloric efficiency. In Exp. 1, 180 nursery pigs (11.86 ± 0.02 kg BW and 39 d of age) were fed 1 of 5 diets for 21 d, with 6 pigs per pen and 6 replications per treatment. Diets were corn-soybean meal based and included 0, 5, 10, 15, or 20% wheat midds. Increasing wheat midds decreased (linear; P < 0.05) ADG and ADFI. Caloric efficiency improved (linear; P < 0.05) on both an ME (NRC, 1998) and NE (Sauvant et al., 2004) basis as dietary wheat midds increased. In Exp. 2, 210 pigs (6.85 ± 0.01 kg BW and 26 d of age) were fed 1 of 5 diets for 35 d, with 7 pigs per pen and 6 replications per treatment. Diets were corn-soybean meal based and contained 0, 5, 10, 15, or 20% wheat midds. Increasing wheat midds did not affect overall ADG or ADFI but decreased (quadratic; P < 0.013) G:F at 20%. Caloric efficiency for both ME and NE improved (quadratic; P < 0.05) as dietary wheat midds increased. In Exp. 3, 180 pigs (12.18 ± 0.4 kg BW and 39 d of age) were fed 1 of 6 experimental diets arranged in a 2 × 3 factorial with main effects of DDGS (0 or 20%) and wheat midds (0, 10, or 20%) for 21 d, with 6 pigs per pen and 5 replications per treatment. No DDGS × wheat midds interactions were observed, and DDGS did not influence ADG, ADFI, or G:F, but increasing dietary wheat midds decreased (linear; P < 0.05) ADG, G:F, and final BW. In Exp. 4, 210 pigs (6.87 kg BW and 26 d of age) were allotted to 1 of 5 dietary treatments, with 7 pigs per pen and 6 replications per treatment. Wheat middlings (0, 10, or 20%) were added to the first 3 diets without balancing for energy. In diets 4 and 5, soybean oil was added (1.4 and 2.8%) to 10 and 20% wheat midds diets to balance to the same NE as the positive control (0% wheat midds). Overall, no wheat midds × fat interactions occurred. Regardless of formulated energy value, caloric efficiency and G:F were poorer (P < 0.05) on an ME basis as wheat midds increased from 10 to 20% of the diet but did not change when calculated on an NE basis. Results of these experiments indicate that wheat midds may be fed up to 10 to 15% of the diet without negatively affecting nursery pig performance and with no interactive effects when fed in combination with DDGS. Also, formulating on an NE basis provided for similar performance with increasing dietary wheat midds compared with a corn-soybean meal control diet.

Effect of dietary zinc and ractopamine hydrochloride on pork chop muscle fiber type distribution, tenderness, and color characteristics.

A total of 320 finishing pigs (PIC 327 × 1050; initially 98 kg) were used to determine the effects of adding Zn to diets containing ractopamine HCl (RAC) on muscle fiber type distribution, fresh chop color, and cooked meat characteristics. Dietary treatments were fed for approximately 35 d and consisted of a corn-soybean meal-based negative control (CON), a positive control diet with 10 mg/kg of RAC (RAC+), and the RAC+ diet plus 75, 150, or 225 mg/kg added Zn from either ZnO or Availa-Zn. Loins randomly selected from each treatment (n = 20) were evaluated using contrasts: CON vs. RAC+, interaction of Zn level × source, Zn level linear and quadratic polynomials, and Zn source. There were no Zn source effects or Zn source × level interactions throughout the study (P > 0.10). Pigs fed RAC+ had increased (P < 0.02) percentage type IIX and a tendency for increased (P = 0.10) percent type IIB muscle fibers. Increasing added Zn decreased (linear, P = 0.01) percentage type IIA and tended to increase (P = 0.09) IIX muscle fibers. On d 1, 2, 3, 4, and 5 of display, pork chops from pigs fed the RAC+ treatment had greater (P < 0.03) L* values compared to the CON. On d 0 and 3 of display, increasing added Zn tended to decrease (quadratic, P = 0.10) L* values and decreased (quadratic, P < 0.03) L* values on d 1, 2, 4, and 5. Pigs fed RAC+ had decreased (P < 0.05) a* values on d 1 and 4 of display and tended to have decreased (P < 0.10) a* values on d 0 and 2 compared to CON pork chops. Pork chops from the RAC+ treatment had a tendency for increased (P < 0.08) oxymyoglobin percentage compared to CON pork chops on d 1, 2, 4, and 5. On d 0, as dietary Zn increased in RAC+ diets, there was a decrease (linear, P < 0.01) in the formation of pork chop surface oxymyoglobin percentage. Metmyoglobin reducing ability (MRA) of pork chops on d 5 was decreased in the RAC+ group. Chops from pigs fed added Zn had increased (quadratic, P < 0.03) MRA on d 3 and 5 of the display period. There was a trend for increased (linear, P = 0.07) cooking loss with increasing Zn in RAC diets and treatments did not affect tenderness as measured by Warner-Bratzler shear force (P > 0.07). In conclusion, RAC+ diets produced chops that were lighter and less red but maintained a greater percentage of surface oxymyoglobin throughout a 5-d simulated retail display. Ractopamine reduced MRA at the end of the display period, but supplementing Zn to RAC diets restored MRA to near CON treatment levels at the end of the display period.

An evaluation of the effects of added vitamin D3 in maternal diets on sow and pig performance.

A total of 84 sows (PIC 1050) and their litters were used to determine the effects of supplementing maternal diet with vitamin D3 on sow and pig performance, serum 25-hydroxyvitamin D3 (25(OH)D3), milk vitamin D3, neonatal bone mineralization, and neonatal tissue vitamin D3. After breeding, sows were randomly assigned to 1 of 3 dietary vitamin D3 treatments (1,500, 3,000, or 6,000 IU/kg of complete diets). Sows were bled on d 0 and 100 of gestation and at farrowing and weaning (d 21). Pig BW was recorded at birth and weaning, and serum was collected from 2 pigs/litter at birth, on d 10 and at weaning. A total of 54 pigs (18/treatment) were euthanized at birth and necropsied to sample bones and tissues. Sow and suckling pig performance and neonatal bone ash and bone density did not differ among maternal vitamin D3 treatments; however, sow 25(OH)D3 and milk vitamin D3 increased (linear, P < 0.01) with increasing maternal vitamin D3 supplementation. Piglet serum 25(OH)D3 increased (quadratic, P < 0.03) with increased maternal vitamin D3. Neonatal kidney vitamin D3 tended (quadratic, P = 0.08) to decrease with increasing maternal vitamin D3, but liver vitamin D3 tended (linear, P = 0.09) to increase with increasing maternal vitamin D3. At weaning, a subsample of 180 pigs (PIC 327 × 1050) were used in a 3 × 2 split plot design for 35 d to determine the effects of maternal vitamin D3 and 2 levels of dietary vitamin D3 (1,800 or 18,000 IU/kg) from d 0 to 10 postweaning on nursery growth and serum 25(OH)D3. Overall (d 0 to 35), nursery ADG and G:F were not affected by either concentration of vitamin D3, but ADFI tended (quadratic, P < 0.06) to decrease with increasing maternal vitamin D3 as pigs from sows fed 3,000 IU had lower ADFI compared with pigs from sows fed 1,500 or 6,000 IU/kg. Nursery pig serum 25(OH)D3 increased with increasing maternal vitamin D3 (weaning) on d 0 (linear, P < 0.01), and maternal × diet interactions (P < 0.01) were observed on d 10 and 21 because pigs from sows fed 1,500 IU had greater increases in serum 25(OH)D3 when fed 18,000 IU compared with pigs from sows fed 3,000 IU. In conclusion, sow and pig serum 25(OH)D3, milk vitamin D3, and neonatal tissue vitamin D3 can be increased by increasing maternal vitamin D3, and nursery pig 25(OH)D3 can be increased by increasing dietary vitamin D3; however, sow and pig performance and neonatal bone mineralization was not influenced by increasing vitamin D3 dietary levels.

Effects of supplemental vitamin D3 on serum 25-hydroxycholecalciferol and growth of preweaning and nursery pigs.

Four experiments were conducted to investigate the effects of varying concentrations of supplemental vitamin D3 on pig growth, feed preference, serum 25-hydroxycholecalciferol [25(OH)D3] , and bone mineralization of nursing and weanling pigs. In Exp. 1, 270 pigs (1.71 ± 0.01 kg BW) were administered 1 of 3 oral vitamin D3 dosages (none, 40,000, or 80,000 IU vitamin D3) on d 1 or 2 of age. Increasing oral vitamin D3 increased serum 25(OH)D3 on d 10 and 20 (quadratic, P < 0.01) and d 30 (linear, P < 0.01). No differences were observed in ADG before weaning or for nursery ADG, ADFI, or G:F. Vitamin D3 concentration had no effect on bone ash concentration or bone histological traits evaluated on d 19 or 35. In Exp. 2, 398 barrows (initially 7 d of age) were used in a 2 × 2 split plot design to determine the influence of vitamin D3 before (none or 40,000 IU vitamin D3 in an oral dose) or after weaning (1,378 or 13,780 IU vitamin D3/kg in nursery diets from d 21 to 31 of age) in a 45-d trial. Before weaning (7 to 21 d of age), oral vitamin D3 dose did not influence growth but increased (P < 0.01) serum 25(OH)D3 at weaning (d 21) and tended (P = 0.08) to increase 25(OH)D3 on d 31. Increasing dietary vitamin D3 concentration from d 21 to 31 increased (P < 0.01) serum 25(OH)D3 on d 31. Neither the oral vitamin D3 dose nor nursery vitamin D3 supplements influenced nursery ADG, ADFI, or G:F. In Exp. 3, 864 pigs (initially 21 d of age) were allotted to 1 of 2 water solubilized vitamin D3 treatments (none or 16,516 IU/L vitamin D3 provided in the drinking water from d 0 to 10) in a 30-d study. Providing vitamin D3 increased serum 25(OH)D3 concentrations on d 10, 20, and 30; however, vitamin D3 supplementation did not affect overall (d 0 to 30) ADG, ADFI, or G:F. In Exp. 4, 72 pigs were used in a feed preference study consisting of 2 feed preference comparisons. Pigs did not differentiate diets containing either 1,378 or 13,780 IU vitamin D3/kg but consumed less (P < 0.01) of a diet containing 44,100 IU vitamin D3/kg compared with the diet containing 1,378 IU vitamin D3/kg. Overall, these studies demonstrate that supplementing vitamin D3 above basal concentrations used in these studies is effective at increasing circulating 25(OH)D3, but the supplement did not influence growth or bone mineralization. Also, concentrations of vitamin D3 of 44,100 IU/kg of the diet may negatively affect feed preference of nursery pigs.

Effects of dietary L-carnitine and ractopamine HCl on the metabolic response to handling in finishing pigs.

Two experiments (384 pigs; C22 × L326; PIC) were conducted to determine the interactive effect of dietary L-carnitine and ractopamine HCl (RAC) on the metabolic response of pigs to handling. Experiments were arranged as split-split plots with handling as the main plot and diets as subplots (4 pens per treatment). Dietary L-carnitine (0 or 50 mg/kg) was fed from 36.0 kg to the end of the experiments (118 kg), and RAC (0 or 20 mg/kg) was fed the last 4 wk of each experiment. At the end of each experiment, 4 pigs per pen were assigned to 1 of 2 handling treatments. Gently handled pigs were moved at a moderate walking pace 3 times through a 50-m course and up and down a 15° loading ramp. Aggressively handled pigs were moved as fast as possible 3 times through the same course, but up and down a 30° ramp, and shocked 3 times with an electrical prod. Blood was collected immediately before and after handling in Exp. 1 and immediately after and 1 h after handling in Exp. 2. Feeding RAC increased (P < 0.01) ADG and G:F, but there was no effect (P > 0.10) of L-carnitine on growth performance. In Exp. 1 and 2, aggressive handling increased (P < 0.01) blood lactate dehydrogenase (LDH), lactate, cortisol, and rectal temperature and decreased blood pH. In Exp. 1, there was a RAC × handling interaction (P < 0.06) for the difference in pre- and posthandling blood pH and rectal temperature. Aggressively handled pigs fed RAC had decreased blood pH and increased rectal temperature compared with gently handled pigs, demonstrating the validity of the handling model. Pigs fed RAC had increased (P < 0.01) LDH compared with pigs not fed RAC. Pigs fed L-carnitine had increased (P < 0.03) lactate compared with pigs not fed L-carnitine. In Exp. 2, pigs fed RAC had lower (P < 0.02) blood pH immediately after handling, but pH returned to control levels by 1 h posthandling. Lactate, LDH, cortisol, and rectal temperature changes from immediately posthandling to 1 h posthandling were not different (P > 0.10) between pigs fed L-carnitine and those fed RAC, indicating that L-carnitine did not decrease recovery time of pigs subjected to aggressive handling. These results suggest that pigs fed 20 mg/kg of RAC are more susceptible to stress when handled aggressively compared with pigs not fed RAC. Dietary L-carnitine fed in combination with RAC did not alleviate the effects of stress. This research emphasizes the importance of using proper animal handling techniques when marketing finishing pigs fed RAC.

Interactive effects of dietary ractopamine HCl and L-carnitine on finishing pigs: I. Growth performance.

A total of 2,152 pigs (C22 × 336 PIC) were used in 4 experiments to determine the interactive effects of dietary l-carnitine and ractopamine HCl (RAC) on finishing pig growth performance. All trials were arranged as factorial arrangements with main effects of l-carnitine (0, 25, or 50 mg/kg in Exp. 1 and 2 and 0 or 50 mg/kg in Exp. 3 and 4) and RAC (0, 5, or 10 mg/kg in Exp. 1 and 0 or 10 mg/kg in Exp. 2, 3, and 4). Dietary carnitine was fed from 38 to 109 kg (Exp. 1 and 3) or for the last 4 or 3 wk before slaughter (118 kg; Exp. 2 and 4, respectively). Ractopamine HCl was fed for 4 wk (Exp. 1, 2, and 3) or 3 wk (Exp. 4) before slaughter. Experiments 1 and 2 were conducted in university research facilities, and Exp. 3 and 4 were conducted in a commercial research facility. All diets were formulated to contain 1.00% total Lys during the last phase of each experiment. In all experiments, pigs fed RAC had increased (P < 0.05) ADG and G:F compared with pigs fed no RAC. Feeding l-carnitine before the RAC feeding period did not affect pig growth performance. In Exp. 1 and 2, l-carnitine did not affect ADG during the last 4 wk; however, in Exp. 2, G:F tended (quadratic; P = 0.07) to improve with increasing l-carnitine. In Exp. 3, l-carnitine × RAC interactions were observed (P < 0.04) for ADG and G:F. Both added l-carnitine and RAC improved performance, but the response was not additive. In Exp. 4, pigs fed l-carnitine had increased (P < 0.04) ADG (0.88 vs. 0.84 kg) and G:F (0.36 vs. 0.35) compared with pigs fed no l-carnitine, and the response was additive to that of RAC. Analysis of treatments common to all experiments showed that pigs fed RAC had increased (P < 0.01) ADG (1.03 vs. 0.93 kg) and G:F (0.40 vs. 0.35) compared with pigs fed no RAC. Pigs fed l-carnitine tended to have increased (P = 0.07) ADG (1.00 vs. 0.96 kg) and improved (P < 0.01) G:F (0.38 vs. 0.37) compared with pigs not fed l-carnitine. These results confirm that RAC improves growth performance of finishing pigs. Added l-carnitine improved growth performance of finishing pigs, and the greatest response was observed in Exp. 3 and 4, which were conducted in commercial research environments. These experiments imply that adding l-carnitine to a finishing diet does not enhance the growth effects of RAC and that effects of RAC and l-carnitine on ADG and G:F are independent.

Interactive effects of dietary ractopamine HCl and L-carnitine on finishing pigs: II. Carcass characteristics and meat quality.

Three experiments using 1,356 pigs (C22 × 336 PIC) were conducted to determine the interactive effects of dietary L-carnitine and ractopamine hydrochloride (RAC) on carcass characteristics and meat quality of finishing pigs. Experiments were arranged as factorials with main effects of L-carnitine and RAC; L-carnitine levels were 0, 25, or 50 mg/kg in Exp. 1 and 2 and 0 or 50 mg/kg in Exp. 3, and RAC levels of 0, 5, or 10 mg/kg in Exp. 1 and 0 or 10 mg/kg in Exp. 2 and 3. Dietary L-carnitine was fed from 38 kg to slaughter (109 and 118 kg in Exp. 1 and 3, respectively) or for 4 wk before slaughter (109 kg in Exp. 2). Ractopamine HCl was fed for 4 wk in all experiments. Exp. 1 and 2 were conducted at university research facilities (2 pigs per pen), and Exp. 3 was conducted in a commercial research barn (23 pigs per pen). In Exp. 1, an L-carnitine × RAC interaction (P < 0.02) was observed for LM visual color, L*, and a*/b*. In pigs fed RAC, increasing L-carnitine decreased L* and increased visual color scores and a*/b* compared with pigs not fed RAC. Ultimate pH tended to increase (linear, P < 0.07) with increasing L-carnitine. Drip loss decreased (linear, P < 0.04) in pigs fed increasing L-carnitine. In Exp. 2, firmness scores decreased in pigs fed increasing L-carnitine when not fed RAC, but firmness scores increased and drip losses decreased with increasing L-carnitine when RAC was added to the diet (L-carnitine × RAC interaction, P < 0.04). Percentage lean was greater (P < 0.01) for pigs fed RAC in Exp. 2. In Exp. 3, fat thickness decreased and lean percentage increased in pigs fed L-carnitine or RAC, but the responses were not additive (L-carnitine × RAC interaction, P < 0.03). Furthermore, pigs fed L-carnitine tended (P < 0.06) to have decreased LM drip loss percentage whereas pigs fed RAC had decreased (P < 0.05) 10th rib and average backfat and decreased drip loss than pigs fed diets without RAC. These results suggest that dietary RAC increased carcass leanness and supplemental L-carnitine reduced LM drip loss when fed in combination with RAC.

Factors affecting storage stability of various commercial phytase sources.

A 360-d study was performed to evaluate the effects of different environmental conditions on storage stability of exogenous phytases. Coated and uncoated products from 3 phytase sources [Ronozyme P (DSM Nutritional Products, Basel, Switzerland), OptiPhos (Phytex LLC, Sheridan, IN), and Phyzyme (Danisco Animal Nutrition, Marlborough, UK)] were stored as pure forms, in a vitamin premix, or in a vitamin and trace mineral (VTM) premix. Pure products were stored at -18, 5, 23, and 37°C (75% humidity). Premixes were stored at 23 and 37°C. Sampling was performed on d 0, 30, 60, 90, 120, 180, 270, and 360. Sampling of the pure products stored at -18 (lack of sample) and 5°C (because of mold growth) was discontinued after d 120. Stability was reported as the residual phytase activity (% of initial) at each sampling point. For the stability of the pure forms, all interactive and main effects of the phytase product, coating, time, and storage temperature were significant (P < 0.01), except for the time × coating interaction. When stored at 23°C or less, pure phytases retained at least 91, 85, 78, and 71% of their initial phytase activity at 30, 60, 90, and 120 d of storage, respectively. However, storing pure products at 37°C reduced (P < 0.01) phytase stability, with OptiPhos retaining the most (P < 0.01) activity. Coating mitigated (P < 0.01) the negative effects of high storage temperature for Ronozyme and OptiPhos (from d 90 onward), but not for Phyzyme. For the stability of phytase in different forms of storage, all interactive and main effects of phytase product, form, coating, time, and temperature of storage were significant (P < 0.01). When stored at room temperature (23°C), retained phytase activities for most the phytase sources were more than 85, 73, and 60% of the initial activity up to 180 d when stored as pure products, vitamin premixes, or VTM premixes, respectively. When stored at 37°C, pure phytase products had greater (P < 0.01) retention of initial phytase activity than when phytases were mixed with the vitamin or VTM premixes. Coated phytases stored in any form had greater (P < 0.01) activity retention than the uncoated phytases at all sampling periods. Results indicate that storage stability of commercially available phytases is affected by duration of storage, temperature, product form, coating, and phytase source. Pure products held at 23°C or less were the most stable. In premixes, longer storage times and higher temperatures reduced phytase activity, but coating mitigated some of these negative effects.

Effects of dietary iodine value product on growth performance and carcass fat quality of finishing pigs.

A total of 120 barrows (initial BW = 47.9 ± 3.6 kg; PIC 1050) were used in an 83-d study to determine the effects of dietary iodine value (IV) product (IVP) on growth performance and fat quality. Pigs were blocked by BW and randomly allotted to 1 of 6 treatments with 2 pigs per pen and 10 pens per treatment. Dietary treatments were fed in 3 phases and formulated to 3 IVP concentrations (low, medium, and high) in each phase. Treatments were 1) corn-soybean meal control diet with no added fat (low IVP), 2) corn-extruded expelled soybean meal (EESM) diet with no added fat (medium IVP), 3) corn-soybean meal diet with 15% distillers dried grains with solubles and choice white grease (DDGS + CWG; medium IVP), 4) corn-soybean meal diet with low CWG (medium IVP), 5) corn-EESM diet with 15% DDGS (high IVP), and 6) corn-soybean meal diet with high CWG (high IVP). On d 83, pigs were slaughtered and backfat and jowl fat samples were collected and analyzed. The calculated and analyzed dietary IVP values were highly correlated (r(2) = 0.86, P < 0.01). Pigs fed the control diet, EESM, or high CWG had greater (P < 0.05) ADG than pigs fed EESM + DDGS. Pigs fed the control diet had greater (P < 0.05) ADFI than pigs fed all other diets. Pigs fed EESM + DDGS and high CWG had improved (P < 0.05) G:F compared with pigs fed the control diet or DDGS + CWG. Pigs fed diets with DDGS had greater (P < 0.05) backfat and jowl fat IV, C18:2n-6, and PUFA and less SFA than pigs fed all other treatments. Pigs fed EESM had greater (P < 0.05) backfat and jowl fat IV, C18:2n-6, and PUFA than pigs fed the control diet, low CWG, or high CWG. Pigs fed low CWG or high CWG had greater (P < 0.05) jowl fat IV than control pigs. Feeding ingredients high in unsaturated fatty acids, such as DDGS and EESM, had a greater impact on fat IV than CWG, even when diet IVP was similar. Therefore, IVP was a poor predictor of carcass fat IV in pigs fed diets with different fat sources and amounts of unsaturated fats formulated with similar IVP. Dietary C18:2n-6 content was a better predictor of carcass fat IV than diet IVP.