Growth performance and carcass traits of pigs subjected to marginal dietary restrictions during the grower phase.

Sixty-four individually housed pigs were used to investigate the effect of amino acid content of finisher diets on growth performance of pigs subjected to marginal dietary amino acid restrictions (80% of the 1988 NRC lysine recommendation) during the grower phase. In each of the two trials, low- and high-amino-acid grower diets (.421 and .765 g lysine/MJ DE, respectively) and four finisher diets (.421, .516, .612, and .707 g lysine/MJ DE) were randomly assigned within sex to 16 gilts and 16 castrated males weighing 23.0 +/- 2.0 kg in a 2 x 4 factorial arrangement of treatments. The average weight of pigs after a completion of diet change was 50.4 +/- 2.1 kg. All pigs were slaughtered at an average weight of 105.2 +/- 4.1 kg. Ultrasound backfat thickness was measured at the time of diet change and before slaughter. Pigs were allowed ad libitum access to feed and water. During the grower phase, pigs fed the high-amino-acid diet grew faster (P < .001) and more efficiently (P < .001) and had less ultrasound backfat (P < .001) than those fed the low-amino-acid diet. The grower diet had no effect on weight gain during the finisher phase. Consequently, pigs fed the high-amino-acid grower diet had better overall weight gain (P < .01) than those fed the low-amino-acid diet. The rate of lean accretion was, however, similar between the two groups of pigs. Furthermore, pigs fed the low-amino-acid grower diet seemed to have better carcass quality, as indicated by less ultrasound backfat (P < .01) and larger carcass longissimus muscle area (P < .05). Average and 10th rib carcass backfat decreased linearly (P < or = .05) and lean accretion rate improved linearly (P < .05) as the amino acid content of finisher diets increased, but there was no grower x finisher diet interaction in these and other response criteria. Although no evidence of compensatory weight gain was observed, it is possible that compensatory lean tissue growth may have occurred in pigs subjected to early amino acid restrictions at the expense of fatty tissue growth.     

Effect of low doses of Aspergillus niger phytase on growth performance, bone strength, and nutrient absorption and excretion by growing and finishing swine fed corn-soybean meal diets deficient in available phosphorus and calcium

Two experiments were conducted to evaluate the efficacy of low doses of Aspergillus niger (AN) phytase for growing and finishing pigs fed corn-soybean meal (SBM) diets with narrow Ca:P ratios that were about 0.9 g/kg deficient in available P and Ca. Experiment 1 utilized 120 pigs with an early finisher period from 51.5 +/- 0.2 to 89.7 +/- 0.9 kg of BW and a late finisher period that ended at 122.5 +/- 2.0 kg of BW. During each period, treatments were the low-P diets with 0, 150, 300, or 450 units (U) of AN phytase added/kg of diet, and a positive control (PC) diet. There were linear increases (P < or = 0.001) in bone strength and ash weight, the absorption of P (g/d and %) and Ca (%), and overall ADG (P = 0.01) with increasing concentration of AN phytase. Pigs fed the diets with 150, 300, or 450 U of AN phytase/kg did not differ from pigs fed the PC diet in growth performance overall, and pigs fed the diets with 300 or 450 U of AN phytase did not differ in P and Ca absorption (g/d) or bone ash weight from pigs fed the PC diet. However, only pigs fed the diet with 450 U of AN phytase/kg had bone strength similar to that of pigs fed the PC diet. Experiment 2 utilized 120 pigs in a grower phase from 25.3 +/- 0.1 to 57.8 +/- 0.8 kg of BW and a finisher phase that ended at 107.6 +/- 1.0 kg of BW. Treatments were the low-P diet with AN phytase added at 300, 500, or 700 U/kg of grower diet, and 150, 250, or 350 U/kg of finisher diet, respectively, resulting in treatments AN300/150, AN500/250, and AN700/350. Growth performance and the absorption (g/d) of P and Ca for the grower and finisher phases were not different for pigs fed the diets containing AN phytase and pigs fed the PC diets. However, pigs fed the PC diets excreted more fecal P (g/d, P < or = 0.01) during the grower and more P and Ca (g/d, P < 0.001) during the finisher phases than the pigs fed the diets with phytase. There were linear increases (P < or = 0.05) in bone strength and bone ash weight with increasing concentration of AN phytase. However, pigs fed the PC diets had a greater bone strength and bone ash weight than pigs fed diets AN300/150, AN500/250 (P < or = 0.02), or AN700/350 (P < or = 0.08). There were no treatment responses for N or DM digestibility in either experiment. Phytase supplementation reduced fecal P excretion from 16 to 38% and fecal Ca excretion from 21 to 42% in these experiments. In conclusion, 450 U of AN phytase/kg was effective in replacing 0.9 g of the inorganic P/kg of corn-SBM diet for finishing swine based on bone strength, whereas 300 or 150 U of AN phytase/kg of diet maintained growth performance of grower or finisher pigs, respectively.     

Degree of amino acid restrictions during the grower phase and compensatory growth in pigs selected for lean growth efficiency

A total of 32 select line (SL) and 32 control line (CL) Duroc pigs were used in two trials to determine the effect of dietary amino acid contents during the grower (G) phase and selection for lean growth efficiency on growth performance, carcass traits, and meat quality. In each trial, pigs weighing 20 kg were assigned to 16 pens with two gilts or two castrated males per pen, and pens were randomly assigned within the genetic line to corn-soybean meal G diets formulated to contain 5.0, 7.0, 9.0, or 11.0 g lysine/kg. After 50 kg, all pigs were fed common finisher 1 (F1) and finisher 2 (F2) diets. Pigs were allowed ad libitum access to feed and water. After the initial statistical analyses, the data sets from the two trials were combined. During the G phase, pigs consumed less feed [linear (Ln), P < 0.001] and more lysine (Ln, P < 0.001), grew faster (Ln, P < 0.05) but utilized feed more and lysine less efficiently (Ln, P < 0.001) for weight gain as the amino acid content of G diets increased. Increasing dietary amino acids resulted in less ultrasound backfat (Ln, P < 0.001) and more serum urea nitrogen [Ln, P < 0.001; quadratic (Qd), P < 0.01] at the end of the G phase. Pigs grew more slowly during the F1 (Ln, P < 0.01 and Qd, P = 0.05) and F2 (Ln, P = 0.07) phases and utilized feed and lysine less efficiently (Ln, P < 0.05) for weight gain during the F1 phase as the amino acid content of G diets increased. The grower diet had no effect on overall weight gain and feed efficiency, carcass traits, or meat quality scores. The efficiency of lysine utilization for overall weight gain (Ln, P < 0.001) and lean accretion (Ln, P < 0.05) improved as the amino acid content of G diets decreased. The SL pigs grew faster (P < 0.05) and had less (P < 0.001) ultrasound backfat throughout the study compared with the CL pigs. The SL pigs had less 10th rib backfat (P < 0.001) and tended to have larger longissimus muscle area (P = 0.09) than the CL pigs, which were reflected in greater rate (P < 0.001) and efficiency (P < 0.05) of lean accretion. Marbling (P < 0.05) and meat color (P = 0.07) scores were lower in the SL pigs. No grower diet x genotype interactions were observed in response criteria of interest. The results indicate that pigs subjected to dietary amino acid restrictions during the G phase (as low as 5.0 g lysine/kg) compensated completely in terms of growth rate and body composition regardless of the genotype. Compensatory growth can have a positive impact not only on the overall efficiency of pig production but also on the environment by reducing excretion of unused nutrients.     

Effect of micronized pea and enzyme supplementation on nutrient utilization and manure output in growing pigs

An experiment was done to determine manure output, N and P excretion, and apparent digestibilities of AA, CP, P, and DM in growing pigs fed barley-based diets containing micronized or raw peas with or without supplementation with enzyme containing primarily beta-glucanase and phytase (Biogal S+). Eight barrows (21.5 +/- 1.2 kg of initial BW) fitted with T-cannulas at the distal ileum were used in a 40-d trial and housed in metabolism cages. Pigs were assigned in a replicated 4 x 4 Latin square design to 4 experimental diets: 1) barley-raw peas control (BRP), 2) barley-micronized peas (BMP), 3) BRP plus enzyme, and 4) BMP plus enzyme (BMP+E). Pigs received 2.6 times maintenance energy requirements based on BW at the beginning of each experimental period. During each experimental period, pigs were acclimatized to their respective diets for 5 d followed by a 3-d period of total fecal and urine collection and another 2-d period of ileal digesta collection. Samples were analyzed for DM, AA (diets and digesta only), N, and P. Wet fecal output of BRP plus enzyme-fed pigs tended to be lower (P = 0.07) than the amount produced by BMP-fed pigs. The amounts of dry feces and urine produced were not different among treatments (P > 0.10). Supplementing the BRP and BMP diet with enzyme increased (P = 0.002) the daily P retained per pig. Pigs fed the enzyme-supplemented diets tended to have lower (P = 0.06) fecal P excretion and greater urinary P excretion (P = 0.001) compared with pigs fed the nonsupplemented diets, but total P excretion was not influenced by diet (P > 0.10). Pigs fed the BMP+E diet retained more (P = 0.006) N per day than pigs fed the BMP diet. However, N excretion was not influenced by dietary treatment (P > 0.10), although BMP+E-fed pigs excreted 13.2% less N in the feces compared with those fed the nonenzyme supplemented controls. Inclusion of micronized peas with or without enzyme supplementation did not affect urinary or fecal N excretion (P > 0.10) compared with the BRP. Dietary treatment had no effect (P > 0.10) on ileal or fecal DM or CP digestibilities. Apparent ileal digestibilities of AA were usually lower (P < 0.05) in the BRP diet compared with the other diets. Enzyme supplementation improved P digestibility at the ileal and fecal level. The current results indicate that utilizing micronized peas in barley-based pig grower diets enhances P retention.     

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.     

Growth performance and carcass characteristics of pigs fed short-season corn hybrids

An experiment was conducted to determine growth performance, carcass characteristics, and fat quality of growing-finishing pigs fed diets based on short-season corn hybrids. Twenty-four individually housed, Cotswold, growing pigs with an initial BW of 41.4 (SD = 1.4) kg were blocked by BW and sex and randomly allotted from within block to 1 of 3 diets to give 8 replicate pigs per diet. Experimental diets consisted of a control based on barley and 2 diets based on corn as the main energy sources. A 3-phase feeding program for 20 to 50 kg (phase I), 50 to 80 kg (phase II), and 80 to 110 kg (phase III) of BW was used. Diets for each phase contained approximately 3.5 Mcal/kg of DE, with total lysine of 0.95, 0.75, and 0.64% in phase I, II, and III diets, respectively. Average daily gain, ADFI, and G:F were monitored weekly during each phase. Pigs were slaughtered after reaching a minimum BW of 100 kg to determine carcass characteristics. There were no effects of diet on ADG, ADFI, and G:F (0.45 +/- 0.02, 0.34 +/- 0.02, and 0.31 +/- 0.02 for phase I, II, and III, respectively). Carcass length, dressing percent, LM area, loin depth, backfat thickness, belly firmness, and L*, b*, and a* fat color were not different across dietary treatments. Pigs fed one corn variety had no differences in fatty acid profile with barley-fed pigs, whereas those fed the other variety of corn had a greater (P < 0.05) concentration of PUFA in their backfat. The results indicate that growth performance, carcass characteristics, and fat quality of pigs fed diets based on short-season corn hybrids and those fed the barley-based diet were not different.     

The influence of dietary field peas (Pisum sativum L.) on pig performance, carcass quality, and the palatability of pork

An experiment was conducted to test the hypothesis that field peas may replace soybean meal in diets fed to growing and finishing pigs without negatively influencing pig performance, carcass quality, or pork palatability. Forty-eight pigs (initial average BW 22.7 +/- 1.21 kg) were allotted to 1 of 3 treatments with 2 pigs per pen. There were 8 replications per treatment, 4 with barrows and 4 with gilts. The treatments were control, medium field peas, and maximum field peas. Pigs were fed grower diets for 35 d, early finisher diets for 35 d, and late finisher diets for 45 d. Pigs receiving the control treatment were fed corn-soybean meal diets. All diets fed to pigs receiving the medium field peas treatment contained 36% field peas and varying amounts of corn; soybean meal was also included in the grower and the early finisher diets fed to pigs on this treatment. In contrast, no soybean meal was included in diets fed to pigs on the maximum field peas treatment, and field peas were included at concentrations of 66, 48, and 36% in the grower, early finisher, and late finisher diets, respectively. Pig performance was monitored within each phase and for the entire experimental period. At the conclusion of the experiment, carcass composition, carcass quality, and the palatability of pork chops and pork patties were measured. Results showed that there were no effects of dietary treatments on ADFI, ADG, or G:F. Likewise, there were no differences in carcass composition among the treatment groups, but gilts had larger (P = 0.001) and deeper (P = 0.003) LM, less backfat (P = 0.007), and a greater (P = 0.002) lean meat percentage than barrows. The pH and marbling of the LM, and the 10th rib backfat were not influenced by treatment, but there was a trend (P = 0.10) for more marbling in barrows than in gilts. The subjective color scores (P = 0.003) and the objective color score (P = 0.06) indicated that dietary field peas made the LM darker and more desirable. Pork chops from pigs fed field peas also had less (P = 0.02) moisture loss compared with chops from pigs fed the control diet. Treatment or sex did not influence palatability of pork chops or pork patties. In conclusion, field peas may replace all of the soybean meal in diets fed to growing and finishing pigs without negatively influencing pig performance, carcass composition, carcass quality, or pork palatability.     

Liquid diets accelerate the growth of early-weaned pigs and the effects are maintained to market weight

Piglets (n = 240, 11.0+/-0.1 d old, 3.93+/-0.05 kg) were allotted to one of four treatments in a 2 x 2 factorial arrangement to examine the effects of diet physical form and nursery environment during the first 14 d after weaning on growth to market weight. During the treatment period, pigs were housed (10 pigs/ pen) in either a conventional hot nursery (30 degrees C) or a segregated-temperature nursery (cool ambient temp. of 24 degrees C, with enclosed hot-box hovers at 32 degrees C). Pigs in each environment were fed nutritionally identical diets in either liquid or dry-pellet form for 14 d. Subsequently, all pigs were fed identical dry diets and were housed in common grower-finisher facilities (penned by sex, five pigs/pen). At the end of the treatment period (d 14), pigs fed the liquid diet were 21% heavier than pigs fed the dry pellet diet (9.22 vs 7.60 kg; P < 0.001). Similarly, gain, feed intake, and gain/feed of liquid-fed pigs were 44%, 18%, and 22% greater, respectively, than observed for pigs fed the dry pellet diet. No main effect of environment was observed (P > 0.10); however, an interaction with diet physical form occurred during the early-nursery period (P < 0.01). Pigs fed the liquid diet showed better performance in the conventional nursery, whereas pigs fed the dry pellet diet were favored in the segregated-temperature nursery. No major differences in growth performance or in ultrasound carcass measurements were detected during the growing-finishing period; however, the advantage in body weight of liquid-fed pigs gained during the first 2 wk postweaning was maintained to the end of the trial (113.9 vs 110.6 kg; P < 0.05). Pigs that were fed the early-nursery diet in liquid form reached market weight (110 kg) 3.7 d sooner than the dry-fed controls (P < 0.01). Estimates of lean gain (calculated from live ultrasound data) were unaffected, suggesting that composition of growth was not altered. Collectively, these results show that liquid feeding during early life can markedly accelerate piglet growth performance and that the growth advantage is maintained to market weight, with no evidence of compensatory gain in the dry-fed control pigs.     

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 mannan oligosaccharides and(or) pharmacological additions of copper sulfate on growth performance and immunocompetence of weanling and growing/finishing pigs

Two experiments were conducted to determine the efficacy of mannan oligosaccharides (MOS) fed at two levels of Cu on growth and feed efficiency of weanling and growing-finishing pigs, as well as the effect on the immunocompetence of weanling pigs. In Exp. 1, 216 barrows (6 kg of BW and 18 d of age) were penned in groups of six (9 pens/treatment). Dietary treatments were arranged as a 2 x 2 factorial consisting of two levels of Cu (basal level or 175 ppm supplemental Cu) with and without MOS (0.2%). Diets were fed from d 0 to 38 after weaning. Blood samples were obtained to determine lymphocyte proliferation in vitro. From d 0 to 10, ADG, ADFI, and gain:feed (G:F) increased when MOS was added to diets containing the basal level of Cu, but decreased when MOS was added to diets containing 175 ppm supplemental Cu (interaction, P < 0.01, P < 0.10, and P < 0.05, respectively). Pigs fed diets containing 175 ppm Cu from d 10 to 24 and d 24 to 38 had greater (P < 0.05) ADG and ADFI than those fed the basal level of Cu regardless of MOS addition. Pigs fed diets containing MOS from d 24 to 38 had greater ADG (P < 0.05) and G:F (P < 0.10) than those fed diets devoid of MOS. Lymphocyte proliferation was not altered by dietary treatment. In Exp. 2, 144 pigs were divided into six pigs/pen (six pens/treatment). Dietary treatments were fed throughout the starter (20 to 32 kg BW), grower (32 to 68 kg BW), and finisher (68 to 106 kg BW) phases. Diets consisted of two levels of Cu (basal level or basal diet + 175 ppm in starter and grower diets and 125 ppm in finisher diets) with and without MOS (0.2% in starter, 0.1% in grower, and 0.05% in finisher). Pigs fed supplemental Cu had greater (P < 0.05) ADG and G:F during the starter and grower phases compared to pigs fed the basal level of Cu. During the finisher phase, ADG increased when pigs were fed MOS in diets containing the basal level of Cu, but decreased when MOS was added to diets supplemented with 125 ppm Cu (interaction, P < 0.05). Results from this study indicate the response of weanling pigs fed MOS in phase 1 varied with level of dietary Cu. However, in phase 2 and phase 3, diets containing either MOS or 175 ppm Cu resulted in improved performance. Pharmacological Cu addition improved gain and efficiency during the starter and grower phases in growing-finishing pigs, while ADG response to the addition of MOS during the finisher phase seems to be dependent upon the level of Cu supplementation.     

Effects of conjugated linoleic acid on the belly firmness and fatty acid composition of genetically lean pigs.

A study of the effects of conjugated linoleic acid (CLA) on the belly firmness and fatty acid composition of genetically lean pigs was conducted. From 75 to 120 kg live weight, 30 gilts were allowed ad libitum access to a corn-soybean meal diet supplemented with either 1% CLA oil (CLA-60) or 1% sunflower oil (SFO) or were fed the sunflower oil-supplemented diet restricted to the amount consumed by pigs fed the CLA-60 diet (RSFO). Conjugated linoleic acid oil consists of 60% positional and geometric isomers of CLA. Pigs fed SFO exhibited higher average daily gains (0.98 vs 0.80 kg/d, P < 0.01) than RSFO-fed pigs, but there were no effects of dietary treatment on feed intake or feed efficiency. Dietary treatment did not affect (P > 0.05) backfat thickness or longissimus muscle area. Bellies of gilts fed CLA-60 were subjectively evaluated to be firmer (2.91 vs 2.43 or 2.07 +/- 0.13, P < 0.01) than those of SFO- or RSFO-fed gilts, respectively. The longissimus muscle of gilts fed CLA-60 contained more saturated fatty acids (39.77 vs. 36.04 or 36.73 +/- 0.74%, P < 0.001) and less unsaturated fatty acids (60.23 vs 63.96 or 63.27 +/- 0.74%, P < 0.001) than that of gilts fed SFO or RSFO, respectively. The belly fat of gilts fed CLA-60 contained more saturated fatty acids (44.45 vs. 37.50 or 36.60 +/- 0.46%, P < 0.001) and less unsaturated fatty acids (54.78 vs. 61.75 or 62.47 +/- 0.46%, P < 0.001), resulting in lower iodine values (57.69 vs 66.37 or 65.62 +/- 0.91, P < 0.001) than that of gilts fed SFO or RSFO, respectively. Gilts fed CLA-60 accumulated more CLA in the longissimus muscle (0.55 vs 0.09 or 0.09 +/- 0.03%, P < 0.01) and belly fat (1.56 vs. 0.13 or 0.13 +/- 0.15%, P < 0.001) than did gilts fed SFO or RSFO, respectively. Dietary treatment did not affect (P > 0.05) 24-h pH, drip loss or subjective quality evaluations of the longissimus muscle. The effect of supplemental CLA to improve belly firmness is of practical significance and may provide a nutritional solution to carcass fat and belly firmness problems, thereby enhancing the overall value of extremely lean carcasses.     

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.     

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.     

Growth performance of 20- to 50-kilogram pigs fed low-crude-protein diets supplemented with histidine, cystine, glycine, glutamic acid, or arginine

The purpose of this investigation was to compare the growth performance of grower pigs fed low-CP, corn-soybean meal (C-SBM) AA-supplemented diets with that of pigs fed a positive control (PC) C-SBM diet with no supplemental Lys. Five experiments were conducted with Yorkshire crossbred pigs, blocked by BW (average initial and final BW were 21 and 41 kg, respectively) and assigned within block to treatment. Each treatment was replicated 4 to 6 times with 4 or 5 pigs per replicate pen. Each experiment lasted 28 d and plasma urea N was determined at the start and end of each experiment. All diets were formulated to contain 0.83% standardized ileal digestible Lys. All the experiments contained PC and negative control (NC) diets. The PC diet contained 18% CP and was supplemented with only DL-Met. The NC diet contained 13% CP and was supplemented with L-Lys, DL-Met, L-Thr, and L-Trp. The NC + Ile + Val diet was supplemented with 0.10% Val + 0.06% Ile. The NC + Ile + Val diet was supplemented with either His (Exp. 1), Cys (Exp. 2), Gly (Exp. 2, 3, and 4), Glu (Exp. 3), Arg (Exp. 4), or combinations of Gly + Arg (Exp. 4 and 5) or Gly + Glu (Exp. 5). Treatment differences were considered significant at P < 0.10. In 3 of the 4 experiments that had PC and NC diets, pigs fed the NC diet had decreased ADG and G:F compared with pigs fed the PC diet. The supplementation of Ile + Val to the NC diet restored ADG in 4 out of 5 experiments. However, G:F was less than in pigs fed the PC diet in 1 experiment and was intermediate between the NC and PC diets in 3 experiments. Pigs fed supplemental Ile + Val + His had decreased G:F compared with pigs fed the PC. Pigs fed supplemental Cys to achieve 50:50 Met:Cys had decreased G:F compared with pigs fed the PC. Pigs fed Ile + Val + 0.224% supplemental Gly had similar ADG, greater ADFI, and decreased G:F compared with pigs fed the PC. Pigs fed Ile + Val + 0.52% supplemental Gly had ADG and G:F similar to that of pigs fed the PC. Pigs fed supplemental Glu had decreased G:F compared with pigs fed the PC. Pigs fed Ile + Val + 0.48% supplemental Arg had decreased G:F compared with pigs fed the PC. Pigs fed the diet supplemented with Gly + Arg had ADG and G:F similar to pigs fed the PC. Pigs fed the low-CP diets had reduced plasma urea N compared with pigs fed PC. The results of these experiments indicate that supplementing Gly or Gly + Arg to a low-CP C-SBM diet with 0.34% Lys, Met, Thr, Trp, Ile, and Val restores growth performance to be similar to that of pigs fed a PC diet with no Lys supplementation.     

Interactive effect of ractopamine and dietary fat source on quality characteristics of fresh pork bellies

Crossbred pigs (n = 216) were used to test the interaction, if any, of ractopamine (RAC) and dietary fat source on the characteristics of fresh pork bellies. Pigs were blocked by BW (77.6 +/- 6.5 kg) and allotted randomly to pens (6 pigs/pen). After receiving a common diet devoid of RAC for 2 wk, pens within blocks were assigned randomly to 1 of 4 treatments arranged in a 2 x 2 factorial design, with 5% fat (beef tallow vs. soybean oil) and RAC (0 vs. 10 mg/kg). At the conclusion of the 35-d feeding period, pigs were slaughtered at a commercial pork packing plant (average BW of 108.8 +/- 0.6 kg), and fresh bellies were captured during carcass fabrication. Neither RAC (P = 0.362) nor fat source (P = 0.247) affected belly thickness. Subjective (bar-suspension) or objective (compression test) measures of belly firmness were not (P > or = 0.148) affected by the inclusion of RAC in the diet; however, bellies from pigs fed soybean oil (SBO) were softer than those from pigs fed beef tallow (BT), as indicated by perpendicular (P < or = 0.005) and parallel (P < 0.001) suspensions. Moreover, bellies from BT-fed pigs required more (P = 0.096) force to compress 50% of their thickness than bellies from SBO-fed pigs (52.29 vs. 43.51 kg). Color (L*, a*, and b* values) of the belly lean and fat was not (P > or = 0.131) affected by RAC, and lean color was similar (P > or = 0.262) between fat sources; however, belly fat from BT-fed pigs was lighter (P = 0.030) and redder (P = 0.013) in color than belly fat from SBO-fed pigs. Bellies of SBO-fed pigs had greater (P < 0.001) proportions of PUFA and lower (P < 0.001) proportions of SFA and MUFA than belly fat from pigs fed BT. Regardless of the RAC inclusion level, PUFA:SFA and iodine values were lower in belly fat from pigs fed BT than SBO; however, within SBO-fed pigs, PUFA:SFA and iodine values were further increased by feeding RAC (RAC x fat source, P < 0.001). As expected, dietary fat source altered the fatty acid composition of fresh pork bellies, which subsequently impacted fresh belly firmness. Interestingly, including RAC in swine finishing diets exacerbated the effect of feeding SBO on pork fat polyunsaturation.     

Evaluation of various extracted vegetable oils, roasted soybeans, medium-chain triglyceride and an animal-vegetable fat blend for postweaning swine

A total of 280 crossbred pigs weaned at 21 d of age and weighing approximately 6 kg were utilized in five replicates to evaluate pig growth responses when fed a basal diet or one of several dietary lipid sources during a 4-wk postweaning period. A basal corn-soybean meal-corn starch-dried whey diet was compared with diets supplemented at a 7.75% level with one of the following lipid sources: corn oil, coconut oil, soybean oil, medium-chain triglyceride (MCT) or an animal-vegetable blend. A sixth treatment evaluated a roasted soybean diet formulated to an energy:lysine level equivalent to that of the fat-supplemented diets. In Exp. II, 36 crossbred weanling barrows were used to determine apparent fat and N digestibilities when soybean oil, roasted soybean, coconut oil or the MCT-supplemented diets were fed. Although pigs fed coconut oil grew somewhat faster, fat inclusion generally did not increase pig growth rate or result in lowered feed intake during the initial weeks postweaning; during the latter portion of the starter phase the addition of dietary fat resulted in a higher growth rate but feed intake was unaffected, resulting in an overall improvement in feed-to-gain ratio (P less than .05) for all but the roasted soybean diet. Pigs fed coconut oil had higher serum triglyceride and lower serum urea concentrations than did pigs fed diets containing most other lipid sources. Pigs fed MCT and coconut oil diets had a higher (P less than .01) apparent fat digestibility during the initial 2 wk postweaning than pigs fed soybean oil or roasted soybean diets. Pigs fed MCT and roasted soybeans had poorest growth rates; apparent fat and N digestibilities were lowest (P less than .05) for the roasted soybean diet.     

Effects of modified tall oil versus a commercial source of conjugated linoleic acid and increasing levels of modified tall oil on growth performance and carcass characteristics of growing-finishing pigs

Two experiments were conducted to evaluate the effects of conjugated linoleic acid (CLA)-enriched feed additives for swine. These additives included a source of CLA that was commercially available (CLA-60) and modified tall oil (MTO). Experiment 1 used 36 barrows (initially 37.6+/-2.8 kg) to compare the effects of CLA-60 and MTO on growth performance and carcass characteristics of finishing pigs. The corn-soybean meal diets contained .50% soybean oil (control), .50% CLA-60, or .50% MTO. Pigs fed CLA-60 had less (P = .03) ADG from 37.6 to 72.6 kg than the control pigs; otherwise, pigs fed either CLA-60 or MTO had growth performance similar (P > .15) to that of the control pigs. Pigs fed MTO grew faster (P = .03) and consumed more feed (P = .10) over the duration of the experiment (37.6 to 106.4 kg) than pigs fed CLA-60. Dietary treatment did not affect (P > .15) plasma triglycerides or carcass characteristics, but pigs fed either MTO or CLA-60 had greater saturation of fatty acids in the adipose tissue at the 10th rib than pigs fed the control diet. Experiment 2 used 80 barrows (initially 33.4+/-2.2 kg) to examine the effects of increasing levels of MTO on growth performance and carcass characteristics of finishing pigs. The corn-soybean meal diet contained 1% cornstarch, which was replaced with MTO to give dietary levels of .25, .50, or 1.00% MTO. Dietary treatment did not affect (P > .15) growth performance. Feeding increasing levels of MTO quadratically decreased (P = .02) average backfat thickness and longissimus muscle drip loss (P = .04) and quadratically increased longissimus muscle area (P = .07) and percentage lean (P = .03). Feeding MTO tended to increase belly firmness (P < .10) compared with pigs fed the control diet. These traits appeared to be optimized with .50% MTO. In summary, pigs fed MTO had greater ADG, ADFI, and ending BW than pigs fed CLA-60. Feeding MTO does not appear to affect growth performance but improves carcass lean content and may additionally improve some aspects of meat quality in growing-finishing pigs.     

Effects of dried whey and copper sulfate on the growth responses to organic acid in diets for weanling pigs

Five 21-d to 28-d experiments involving 484 pigs weaned at 28 +/- 2 d of age were conducted to evaluate the effects of addition of organic acid to a fortified, corn-soybean meal diet (CS) or to a similar diet containing 15% dried whey (CSW) on performance of pigs. The effects of an antibiotic-sulfonamide combination (110 mg chlortetracycline, 110 mg sulfamethazine, 55 mg penicillin/kg) and the interactive effects of Cu sulfate (250 ppm Cu) and acid also were evaluated. The acid was a commercial product consisting of 96% organic acid (citric acid and Na citrate, 2:1). Treatments in Exp. 1 and 2 were factorial arrangements of the CS or CSW basal diets supplemented with 0 or 1% (Exp. 1) and 0, .5 or 1% (Exp. 2) of the acid product. Pigs fed diets containing whey consumed more feed (P less than .01) and gained weight faster (P less than .05), but they had feed/gain responses similar to those of pigs fed the CS diet. Addition of 1% acid improved (P less than .01) growth rate of pigs fed the CS diet but did not improve (P greater than .25) growth rate of pigs fed the CSW diet. Feed/gain was improved (P less than .01) by acid addition to both the CS and the CSW diets. Improvements in gain and feed/gain were similar for the two levels of acid. In Exp. 3 and 4, factorial combinations of 0 and 1% acid and 0 and 250 ppm Cu were evaluated in diets containing an antibiotic-sulfonamide combination. In addition, a negative control diet (no antibiotics, acid or Cu) was included. Pigs fed diets containing antibiotics gained faster and more efficiently (P less than .01) than those fed the control diet.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effects of dietary iron supplementation on growth performance, hematological status, and whole-body mineral concentrations of nursery pigs

An experiment was conducted to evaluate the effects of supplementing increasing concentrations of Fe to the diet of nursery pigs on growth performance and indices of hematological and mineral status. Pigs (n = 225; 6.5 kg; 19 +/- 3 d) were allotted randomly by BW, litter, and gender to one of five dietary treatments (five pigs per pen; nine pens per treatment). Basal diets for each phase (Phase 1: d 0 to 7; Phase 2: d 7 to 21; Phase 3: d 21 to 35) were formulated to contain minimal Fe concentration and then supplemented with 0, 25, 50, 100, and 150 mg Fe/kg of diet (as-fed basis) from ferrous sulfate. Three pigs per pen (n = 135) were chosen and bled throughout (d 0, 7, 21, and 35) to determine hemoglobin (Hb), hematocrit (Hct), transferrin (Tf), and plasma Fe (PFe). In addition, pigs (n = 5; 5.9 kg; 19 +/- 3 d) from the contemporary group were killed at d 0 to establish baseline (BL), and 30 pigs (six pigs/treatment) were killed at d 35 to determine whole-body and liver mineral concentrations. The improvements in growth performance during Phase 2 (ADG = linear, P = 0.04; ADFI = linear, P = 0.10; G:F = quadratic, P = 0.07) were of sufficient magnitude that dietary treatments tended to increase ADG (linear, P = 0.08), ADFI (quadratic, P = 0.09), and G:F (quadratic, P = 0.10) for the 35-d experiment. Hematological variables were not affected until d 21, at which time dietary Fe supplementation resulted in a linear increase (P = 0.03) in Hb, Hct, and PFe. This linear increase (P = 0.001) was maintained until d 35 of the experiment; however, dietary treatments resulted in a linear decrease (P = 0.01) in Tf on d 35. Whole-body Fe concentration increased (linear, P = 0.01) in pigs due to increasing dietary Fe concentrations. Moreover, pigs fed for 35 d had greater (P = 0.02) whole-body Fe, Zn, Mg, Mn, Ca, and P concentrations and lower (P = 0.001) whole-body Cu concentration than BL. Hepatic Fe concentration increased (linear, P = 0.001) in pigs due to dietary treatments; however, the hepatic Fe concentration of all pigs killed on d 35 was lower (P = 0.001) than the BL. Results suggest that Fe contributed by feed ingredients was not sufficient to maintain indices of Fe status. The decrease in Fe stores of the pigs was not severe enough to reduce growth performance. Even so, the lessening of a pig's Fe stores during this rapid growth period may result in the occurrence of anemia during the subsequent grower and finisher periods.     

A genetically engineered Escherichia coli phytase improves nutrient utilization, growth performance, and bone strength of young swine fed diets deficient in available phosphorus

A 28-d experiment was conducted using 126 crossbred barrows to evaluate the addition of a genetically engineered Escherichia coli phytase to diets that were 0.15% deficient in available P. Growth performance, bone strength, ash weight, and the apparent absorption of P, Ca, Mg, N, energy, DM, Zn, Fe, and Cu were the response criteria. The pigs (2 pigs/pen) averaged 7.61 kg of BW and 30 d of age initially. The low-P basal diet was supplemented with 0, 100, 500, 2,500, or 12,500 units (U) of E. coli phytase/kg of diet, or 500 U of Peniophora lycii phytase/kg of diet. The positive control (PC) diet was adequate in available P. Pigs were fed the diets in meal form. Fecal samples were collected from each pig from d 22 to 27 of the experiment. There were linear and quadratic increases (P < 0.001) in 28-d growth performance (ADFI, ADG, and G:F), bone breaking strength and ash weight, and the apparent absorption (g/d and %) of P, Ca, and Mg (P < or = 0.01 for quadratic) with increasing concentrations of E. coli phytase. Pigs fed the low-P diets containing 2,500 or 12,500 U/kg of E. coli phytase had greater (P < or = 0.01 or P < 0.001, respectively) values for growth performance, bone breaking strength and ash weight, and the apparent absorption (g/d and %) of P, Ca, and Mg than pigs fed the PC diet. The addition of E. coli phytase did not increase the apparent percentage absorption of N, GE, DM, Zn, Fe, or Cu. There were no differences in the efficacy of the E. coli or P. lycii phytase enzymes at 500 U/kg of low-P diet for any criterion measured. In conclusion, there were linear increases in growth performance, bone breaking strength and ash weight, and the apparent absorption of P, Ca, and Mg with increasing addition of E. coli phytase up to 12,500 U/kg of diet. Also, all of these criteria were greater for pigs fed the low-P diets containing 2,500 or 12,500 U of E. coli phytase/kg than for pigs fed the PC diet. The addition of 500, 2,500, or 12,500 U of E. coli phytase/kg of low-P diet reduced P excretion (g/d) in manure by 35, 42, and 61%, respectively, compared with pigs fed the PC diet.