Effect of feeding finishing pigs extruded full-fat soybeans on performance and pork quality.

This experiment was designed to test whether changing the type and amount of added dietary fat would affect performance or meat quality. Dietary fat was added as tallow or extruded full-fat soybeans (FFS). Isoenergetic diets containing 10% FFS, 20% FFS, or 4% tallow were fed for 3 or 6 wk before slaughther. A conventional corn-soybean meal diet served as a no-added-fat control. Each of the seven dietary groups contained 20 pigs, equally distributed among four pens, with barrows and gilts segregated. Significance of treatment, sex, and interaction effects were evaluated for 34 meat quality, composition, and sensory evaluation traits. Treatment x sex interactions were not detected (P greater than .05). Treatment main effects were detected for percentage of fat and water in the bacon and for lipid oxidation in bacon and the longissimus muscle. The 6 df for treatment were partitioned into six contrasts to test for the trends within and between diets. A trend toward reduced fat and increased moisture in bacon was detected in the 10% FFS diet over time (P less than .05). In general, lipid oxidation of bacon and longissimus muscle increased with level of FFS in the diet, length of time on the diet, and storage time of the meat. Although statistically significant, the magnitude of these effects was small and did not affect the sensory characteristics of longissimus muscle samples. It was concluded that short-term feeding of FFS before slaughter did not adversely affect animal growth or meat quality.     

Efficacy of chromium picolinate on performance and tissue accretion in pigs with different lean gain potential.

We conducted two experiments to determine whether the efficacy of chromium picolinate (CrP) on growth performance, carcass composition, and tissue accretion rates is dependent on the lean gain potential of the pigs. In Exp. 1, 40 barrows (20 from each of two genetic backgrounds; two pigs per pen, five pens per treatment) were fed a fortified, corn-soybean meal basal diet (.95% lysine from 19 to 55 kg BW; .80% lysine from 55 to 109 kg BW) without or with 200 microg/kg of Cr from CrP. The addition of Cr had no effect on performance, carcass measurements, or accretion rates of carcass protein or lipid, regardless of the lean gain potential of the pigs. In Exp. 2, 60 group-penned pigs (three pigs per pen; five pens per treatment) were fed a fortified, corn-soybean meal basal diet without or with 200 microg/kg of Cr from CrP from 21 to 104 kg BW. Within the dietary Cr treatments, half of the pigs received daily injections of 3 mg of porcine somatotropin (pST) from 54 to 104 kg BW. The pST administration resulted in faster growth rates (P < .007), improved feed efficiency (P < .001), increased longissimus area (P < .001), and decreased 10th-rib backfat (P < .001). Administration of pST also increased the percentage and accretion rate of carcass protein (P < .001) and decreased the percentage and accretion rate of carcass lipid (P < .001). The addition of CrP to the diet had no effect on any variable measured in either the untreated or pST-treated pigs. In these studies, Cr was ineffective at altering the composition of the carcass and its effects were not dependent on the pig's potential for lean gain.     

Soybean meal from roundup ready or conventional soybeans in diets for growing-finishing swine

Dehulled soybean meal prepared from genetically modified, herbicide (glyphosate)-tolerant Roundup Ready soybeans containing the CP4 EPSPS protein and near-isogenic conventional soybeans were assessed in an experiment with growing-finishing pigs. The soybeans were grown in the yr 2000 under similar agronomic conditions except that the Roundup Ready soybeans were sprayed with Roundup herbicide. Both were processed at the same plant. The composition of the two types of soybeans and the processed soybean meal were similar. Corn-soybean meal diets containing conventional or Roundup Ready soybean meal and fortified with minerals and vitamins were fed to 100 cross-bred pigs from 24 to 111 kg BW. Diets contained approximately 0.95% lysine initially and were reduced to 0.80 and 0.65% lysine when pigs reached 55 and 87 kg BW, respectively. There were 10 pens (five pens of barrows and five pens of gilts) per treatment with five pigs per pen. All pigs were scanned at 107 kg mean BW and all barrows were killed at the end of the test for carcass measurements and tissue collection. Rate and efficiency of weight gain, scanned backfat and longissimus area, and calculated carcass lean percentage were not different (P > 0.05) for pigs fed diets containing conventional or Roundup Ready soybean meal. Gilts gained slower, but they were more efficient and leaner (P < 0.05) than barrows. Responses to the type of soybean meal were similar for the two sexes with no evidence of a diet x sex interaction for any of the traits. In most instances, carcass traits of barrows were similar for the two types of soybean meal. Longissimus muscle samples from barrows fed conventional soybean meal tended (P = 0.06) to have less fat than those fed Roundup Ready soybean meal, but water, protein, and ash were similar. Sensory scores of cooked longissimus muscles were not influenced (P > 0.05) by diet. The results indicate that Roundup Ready soybean meal is essentially equivalent in composition and nutritional value to conventional soybean meal for growing-finishing pigs.     

Response of starter pigs to supplementation of corn-soybean meal diets with organic acids

Four growth experiments were conducted to assess the effects of organic acid supplementation on performance of starter and finisher pigs. Three 4-wk starter experiments utilized 392 pigs fed simple corn-soybean meal diets. A fourth experiment employed 135 finisher pigs in a 6-wk study. Each of the starter experiments was initiated immediately after weaning; piglets were 30 +/- 3 d of age. In Exp. 1, weanling pigs fed a 19% crude protein, simple corn-soybean meal diet were compared with pigs fed similar diets supplemented with 2% propionic, fumaric, or citric acid. Addition of each acid improved (P less than .07) efficiency of gain, while propionate depressed (P less than .05) feed intake. Additions of 1, 2, 3 or 4% fumarate were made in Exp. 2, resulting in linear daily gain and feed efficiency improvements (P less than .05). In Exp. 3, a possible protein-sparing effect of fumaric acid was investigated. Increasing protein levels from 16 to 20% improved daily gain (P less than .01) and feed efficiency (P less than .0001); fumarate supplementation (2%) increased (P less than .01) gain:feed. However, there was no protein X fumaric acid interaction. In Exp. 4, no treatment effects were noted with performance of finisher pigs fed a 14% crude protein, corn-soybean meal diet was compared with that of pigs fed similar diets supplemented with 1.5 or 3% fumaric acid.     

Pre- and postweaning performance of pigs injected with dexamethasone at birth

A trial was conducted to determine pre- and postweaning performance of pigs injected with dexamethasone either 1 or 24 h after birth. In Exp. 1, 225 pigs (Triumph4 x PIC Camborough 22) were assigned according to birth weight and sex to three treatments. Treatments included either saline (Control), Dex1 (2 mg/kg BW i.m. injection of dexamethasone within 1 h of birth), or Dex24 (2 mg/kg BW i.m. injection of dexamethasone within 24 h after birth). Birth weights (1.56 +/- 0.06 kg) did not differ among treatments (P > 0.10) or between sexes (P > 0.10). There was a treatment x sex interaction on BW at weaning (15 d; P < 0.05) with Dex1 and Dex24 males 10% heavier than Control males (4.77 and 4.78 vs. 4.34 kg, respectively), and no significant differences in BW among the females (P > 0.05). In Exp. 2, 180 pigs from Exp. 1 were transported to a segregated early weaning nursery facility where each sex was assigned to 10 pens per treatment (60 pens total). Pigs were fed fortified corn-soybean meal diets in a three-phase feeding program. At the end of Exp. 2 (49-d period), there was a treatment x sex interaction (P < 0.01) for BW with Dex1 and Dex24 barrows being on average 8% heavier than the Control barrows (30.1 and 29.8 vs. 27.7 kg, respectively), and no significant difference in BW (P > 0.10) among the gilts. No treatment differences in feed efficiency (gain:feed) were observed during the nursery period (P > 0.10). In Exp. 3, pigs from the nursery were moved to a finishing facility where each sex was assigned to 4 pens per treatment (24 pens total). All pigs were fed fortified corn-soybean meal diets in a four-phase feeding program with sexes fed separately. Real-time ultrasound was used to measure 10th rib backfat depth and longissimus muscle area. At the end of Exp. 3 (83-d period), there was a treatment x sex interaction (P < 0.05) for final BW with Dex1 and Dex24 barrows being on average 5.45 kg heavier than Control barrows (119.6 and 120.7 vs. 114.4 kg, respectively), and no difference (P > 0.05) in BW among the gilts. No treatment differences (P > 0.10) were observed for backfat depth, longissimus muscle area or gain:feed. These studies demonstrate that dexamethasone (2 mg/kg BW) given within 24 h of birth significantly improves both pre- and postweaning performance of barrows with no beneficial effects on gilts.     

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.     

Effects of diet containing extruded full-fat soybeans or butter on the growth, composition, and sensory characteristics of pork.

Ninety-six crossbred barrows were randomly allotted to five replications of four treatments to determine the effects of diets containing 20% extruded full-fat soybeans (FFS) or 4% butter (B) on the growth, composition, and sensory characteristics of finishing pigs. Pigs were housed five per pen, except for one replication that had four pigs per pen, in environmentally regulated barns. Pigs were given ad libitum access to a corn-soybean meal diet for 11 wk (control); a corn-extruded soybeans and soft wheat midds diet for 11 wk (FFS-11); a corn-soybean meal diet for 6 wk, changed to a corn-extruded soybeans and soft wheat midds diet for 5 wk (FFS-5); or a corn-soybean meal diet for 6 wk, changed to a corn-soybean meal, soft wheat midds, and 4% butter diet for 5 wk (B). Feed intake and weight gain were measured once every 2 wk. Pigs were slaughtered and carcass data were collected. Sensory characteristics (tenderness, juiciness, pork flavor intensity, off-flavor intensity, and overall acceptability), shear force, moisture, and fat content were determined for the longissimus muscle. Sensory characteristics (pork flavor, off-flavor, rubbery, cohesiveness, and juiciness) and 2- thiobarbituric acid values were determined for ground pork (30% fat) after 1, 4, and 7 d for control, FFS-11, and B treatments. No differences (P > .05) in ADG were observed between diets. Feed efficiency of the FFS-11 group was better (P < .05) than that of the control or B groups. No consistent differences were observed for carcass, sensory, or shear-force characteristics of the longissimus muscle or ground pork.(ABSTRACT TRUNCATED AT 250 WORDS)     

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.     

Effect of magnesium mica on performance and carcass quality of growing-finishing swine

A total of 240 crossbred pigs were used in two experiments to determine the effect of feeding magnesium mica (MM) during the growing-finishing period on animal performance and pork carcass characteristics. All pigs were blocked by weight, and treatments were assigned randomly to pens (five pigs/pen) within blocks. In each experiment, eight pens were allotted randomly to one of three treatments: 1) a negative control corn-soybean meal starter, grower, and finisher diet devoid of supplemental magnesium; 2) the control diets supplemented with 1.25% MM; and 3) the control diets supplemented with 2.50% MM. In Exp. 1, pigs were slaughtered at the University of Arkansas Red Meat Abattoir, whereas pigs in Exp. 2 were transported to a commercial pork packing plant and slaughtered according to industry-accepted procedures. In both experiments, dietary supplementation of MM had no (P > .10) effect on ADG, ADFI, or gain:feed ratio at any phase during the growing-finishing period. In Exp. 1, MM supplementation had no (P > .10) effect on carcass fatness or muscling. Moreover, Japanese color scores were not (P > .10) affected by feeding pigs MM; however, American color scores increased linearly (P < .01) with increasing levels of MM in the diet. Although MM supplementation did not (P > .10) affect L* and b* values for the longissimus muscle (LM), there was a linear increase (P < .05) in LM a* and chroma values associated with increased MM levels in swine diets. In Exp. 2, carcasses from pigs fed 1.25% MM had less (P < .05) fat opposite the LM at the 10th rib than untreated controls and pigs fed 2.50% MM and higher (P < .10) percentages of muscle than carcasses of untreated controls. Moreover, the LM from pigs fed 1.25% MM was less (P < .05) red and less (P < .05) yellow than the LM from pigs fed the control or 2.50% MM-supplemented diets. Drip loss from the LM was unaffected (P > .10) by inclusion of MM in the diet. Results from this study confirm that inclusion of MM, an inexpensive, inorganic magnesium source, in diets of growing-finishing swine has beneficial effects on pork carcass cutability and quality with no deleterious effects on live animal performance.     

Effect of feather meal on live animal performance and carcass quality and composition of growing-finishing swine

A total of 252 crossbred pigs were used in two experiments to determine the effect of feeding hydrolyzed feather meal (FM) during the growing-finishing period on animal performance, carcass composition, and pork quality. All pigs were blocked by weight, and dietary treatments were assigned randomly to pens within blocks. In Exp. 1, 24 pens were randomly assigned to one of three dietary treatments: 1) control corn-soybean meal starter, grower, and finisher diets devoid of FM; 2) control diets formulated with 3% FM; and 3) control diets formulated with 6% FM. During the starter phase, there was a quadratic decrease in average daily gain (P < 0.06) and gain:feed (P < 0.01) with increasing FM, and during the grower-II phase, gain:feed increased linearly (P < 0.07) with increasing FM inclusion level. However, dietary FM had no effects (P > 0.10) on performance during the grower-I phase, finisher phase, or in the overall trial. Moreover, carcasses from pigs fed 3% FM had greater (P < 0.05) average backfat depth than carcasses of pigs fed 0 and 6% FM, but FM did not affect (P > 0.10) ham or carcass lean composition. In Exp. 2, 24 pens were randomly allotted to one of four dietary treatments: 1) positive control corn-soybean meal-based starter, grower, and finisher diets; 2) negative control corn-soybean meal- and wheat middlings-based starter, grower, and finisher diets; 3) negative control diets formulated with 3% FM; and 4) negative control diets formulated with 6% FM. Dietary FM had no effect (P > 0.10) on average daily gain, average daily feed intake, or gain:feed during any phase of the experiment. Ham weight decreased linearly (P < 0.04), whereas ham lean weight increased linearly (P < 0.09), with increasing levels of FM in the diet. Pork from pigs fed 3% FM tended (quadratic effect, P < 0.10) to receive higher Japanese color scores than pork from pigs fed either negative control or 6% FM diets. Moreover, pork color became lighter (P c 0.08), less red (P < 0.001), and less yellow (P < 0.003) as FM level was increased in swine diets. Results from these two experiments indicate that as much as 6% FM can be incorporated into isolysinic diets of growing-finishing pigs without adversely impacting animal performance, carcass composition, or pork quality.     

Assessment of energy content of low-solubles corn distillers dried grains and effects on growth performance, carcass characteristics, and pork fat quality in growing-finishing pigs

Two studies were conducted to assess the energy content of low-solubles distillers dried grains (LS-DDG) and their effects on growth performance, carcass characteristics, and pork fat quality in grow-finish pigs. In Exp. 1, 24 barrows (Yorkshire-Landrace × Duroc; 80 to 90 d of age) in 2 successive periods were assigned to 1 of 6 dietary treatments. In individual metabolism stalls, pigs were fed a corn-soybean meal diet (control); control replaced by 30, 40, or 50% LS-DDG; or control replaced by 30 or 40% distillers dried grains with solubles (DDGS) at 3% of their initial BW for 12 d. All diets contained 0.25% CrO(2). During the 5-d collection period, feces and urine were collected from each pig. Feed, feces, and urine were analyzed for DM, GE, and N concentrations, and feed and feces were analyzed for Cr content. The ME content of LS-DDG (2,959 ± 100 kcal/kg of DM) was similar to that determined for DDGS (2,964 ± 81 kcal/kg of DM). In Exp. 2, 216 Yorkshire-Landrace × Duroc pigs were blocked by initial BW (18.8 ± 0.76 kg) and assigned to 1 of 24 pens (9 pigs/pen). Pens within block were allotted to 1 of 3 dietary treatments (8 pens/treatment) in a 4-phase feeding program: a corn-soybean meal control (control), control containing 20% LS-DDG, or control containing 20% DDGS. Treatment had no effect on final BW, ADG, ADFI, or HCW. Pigs fed LS-DDG had similar G:F (0.367) compared with pigs fed DDGS (0.370), but tended (P = 0.09) to have decreased G:F compared with pigs fed the control (0.380; pooled SEM = 0.004). Dressing percent was less (P < 0.01) for pigs fed LS-DDG (72.8%) and DDGS (72.8%) compared with the control (73.8%; pooled SEM = 0.22). Pigs fed LS-DDG (54.8%) had greater (P = 0.02) carcass lean compared with pigs fed DDGS (53.4%), but were similar to pigs fed control (54.1%; pooled SEM = 0.33). Bellies from pigs fed DDGS (12.9°) were softer (P < 0.01) than those from pigs fed control (17.7°; pooled SEM = 1.07) as determined by the belly flop angle test. Feeding LS-DDG (14.1°) tended (P < 0.10) to create softer bellies compared with control-fed pigs. The PUFA content of belly fat was reduced (P < 0.01) by LS-DDG (14.0%) compared with DDGS (15.4%), but was increased (P < 0.05) compared with pigs fed the control (9.4%; pooled SEM = 0.34). In conclusion, LS-DDG and DDGS had similar ME values and inclusion of 20% LS-DDG in diets for growing-finishing pigs supports ADG and ADFI similar to that of diets containing 20% DDGS, and may reduce negative effects on pork fat compared with DDGS.     

Effect of dietary fat on pig performance and dust levels in modified-open-front and environmentally regulated confinement buildings

Four trials were conducted with 1,480 pigs (initial wt: 23 kg in trial 1,29 kg in trial 2 and 49 kg in trial 3 and 4) to determine the effect of dietary fat on pig performance, nutrient separation in an automated feed distribution system, dust levels in swine buildings and integrity of the respiratory system of swine. Two modified-open-front (B-1 and B-2) and two environmentally regulated (E-1 and E-2) growing-finishing buildings, of identical design, were used in each trial. In trial 1, 250 pigs (25 pens of 10 pigs/pen) in B-1 were fed a ground, mixed, corn-soybean meal diet (15% crude protein) with added tallow (5%), and 250 pigs in B-2 were fed the same diet but without added tallow. The assignment of diets to buildings were reversed in trial 2 in which 2.5% tallow was used instead of 5%. Each diet was fed ad libitum to pigs, and was distributed by an automated "Flexauger" system in trials 1 and 2. In each of trials 3 and 4, 120 pigs (12 pens of 10 10 pigs/pen) in E-1 were fed a corn-soybean meal diet (14% crude protein) with added tallow (5%) and 120 pigs in E-2 were fed the same diet but without added tallow. Overall, pigs fed the diet with tallow gained faster (P less than .002), consumed less feed (P less than .02) and converted feed more efficiently (P less than .002) than those fed the diet without tallow in trials 1 and 2. Pig performance was also improved by the addition of tallow to the diet in trials 3 and 4 (P less than .002). Crude protein, Ca, P and Cu contents of both diets were similar at each location sampled throughout the automated distribution system in trials 1 and 2. Addition of tallow to the diets reduced aerial dust levels, both with the feed distribution auger running (P less than .002) and without the auger running (P = .06) in trials 1 and 2. In trials 3 and 4, adding 5% tallow to the diet reduced aerial dust concentrations of of particle sizes of 14, 4, and 1.5 micron (P less than .002) and .4 micron (P = .07). The amount of settled dust was lower (P less than .001, trials 1, 3 and 4) when tallow was included in the diet.(ABSTRACT TRUNCATED AT 400 WORDS)     

Evaluation of the effect of fumaric acid and sodium bicarbonate addition on performance of starter pigs fed diets of different types.

Three growth experiments were conducted to assess the effect of fumaric acid (FA) supplementation on the performance of pigs fed different types of diets. These 4-wk experiments involved 550 crossbred pigs weaned at 30 +/- 3 d of age. Pigs in Exp. 1 were fed either a simple corn-soybean meal (SBM) diet or a 75% corn-SBM, 25% dried skim milk (DSM) diet. Zero, 2, or 3% FA were added to the diets to create a 2 x 3 factorial arrangement of treatments. Supplementing diets with DSM improved gain (P less than .05) and gain/feed (P less than .001). Fumaric acid addition improved efficiency of feed utilization (P less than .01). Experiment 2 was conducted to evaluate the effect of protein source (casein or soy protein concentrate [SPC]) on the response to 3% FA. Sodium bicarbonate (BCB; 2.75%) was added to one diet containing casein and FA to negate the effect of FA on growth performance. Addition of FA improved gain and feed efficiency (P less than .05) during the first 2 wk.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effects of nitrogen and energy source on nutrient digestibility in the young pig

Dried whole whey, lard or dried skim milk was added to a corn-soybean meal basal diet to determine the effect on apparent nitrogen (ND), energy (ED) and dry matter digestibility (DMD) in pigs weaned at 28 d. Four groups of four littermate barrows were allotted to the experimental diets and placed in individual metabolism pens for 12 d (3 d adjustment and three collection periods of 3 d each) after weaning. The study was a 4 X 3 factorial with diet and period as main effects. Addition of dried skim milk or dried whey to the diet resulted in higher values (P less than .05) for DMD and ED as compared with the basal or corn-soy and lard diet. Pigs fed added dried skim milk had improved (P less than .05) ND over pigs on other dietary treatments. All nutrient digestibility coefficients increased (P less than .05) from period 1 to period 2, and ND increased (P less than .05) from period 2 to 3. It was concluded that the young pig requires at least 6 to 9 d after weaning at 28 d to adjust to typical corn-soybean meal starter diets.     

Effects of ractopamine on genetically obese and lean pigs

Twenty-eight genetically obese and 24 lean barrows (65.0 and 68.7 kg average BW, respectively) were allotted within genotype to a 16% CP corn-soybean meal basal diet or this basal diet + 20 ppm ractopamine (a phenethanolamine beta-adrenergic agonist) and allowed ad libitum access to feed for 48 d. Compared to lean pigs, obese pigs had lower ADG, gain to feed ratio, longissimus muscle area, predicted amount of muscle, and weights of trimmed loin and ham, ham lean, heart, spleen, kidney and gastrointestinal tract (P less than .05). Obese pigs also had shorter carcass but higher dressing percentage, backfat thickness, fat depth, fat area, untrimmed loin weight and fasting plasma urea N concentration (P less than .05). Dietary supplementation with 20 ppm ractopamine reduced daily feed intake and improved gain to feed ratio in both lean and obese pigs (P less than .05). Pigs fed ractopamine had shorter carcasses, less fat depth and fat area, smaller weights of stomach and colon plus rectum, but higher dressing percentages, longissimus muscle areas, weights of trimmed Boston butts, picnics and loins, ham lean and predicted amounts of muscle than pigs not fed ractopamine (P less than .05). Supplemental ractopamine had no effect on fasting plasma concentrations of urea N, nonesterified fatty acids, triglyceride or glucose (P greater than .05). No genotype x ractopamine interactions for the criteria described above were detected (P greater than .05). These results suggest that ractopamine will improve the efficiency of feed utilization and carcass leanness in swine with different propensities for body fat deposition.     

Effects of choice white grease or poultry fat on growth performance, carcass leanness, and meat quality characteristics of growing-finishing pigs.

Eighty-four crossbred gilts were used to evaluate the effects of dietary choice white grease (CWG) or poultry fat (PF) on growth performance, carcass characteristics, and quality characteristics of longissimus muscle (LM), belly, and bacon of growing-finishing pigs. Pigs (initially 60 kg) were fed a control diet with no added fat or diets containing 2, 4, or 6% CWG or PF. Diets were fed from 60 to 110 kg and contained 2.26 g lysine/Mcal ME. Data were analyzed as a 2 x 3 factorial plus a control with main effects of fat source (CWG and PF) and fat level (2, 4, and 6%). Pigs fed the control diet, 2% fat, and 4% fat had greater (P < 0.05) ADFI than pigs fed 6% fat. Pigs fed 6% fat had greater (P < 0.05) gain/feed (G/F) than pigs fed the control diet or other fat levels. Subcutaneous fat over the longissimus muscle from pigs fed CWG had more (P < 0.05) moisture than that from pigs fed PF. Feeding dietary fat (regardless of source or level) reduced (P < 0.05) the amount of saturated fats present in the LM. Similarly, 4 or 6% fat decreased (P < 0.05) the amount of saturated fats and increased unsaturated fats present in the bacon. No differences (P > 0.05) were observed for ADG, dressing percentage, leaf fat weight, LM pH, backfat depth, LM area, percentage lean, LM visual evaluation, LM waterholding capacity, Warner-Bratzler shear and sensory evaluation of the LM and bacon, fat color and firmness measurements, or bacon processing characteristics. Adding dietary fat improved G/F and altered the fatty acid profiles of the LM and bacon, but differences in growth rate, carcass characteristics, and quality and sensory characteristics of the LM and bacon were minimal. Dietary additions of up to 6% CWG or PF can be made with little effect on quality of pork LM, belly, or bacon.     

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.     

The effect of ractopamine hydrochloride on the carcass cutting yields of finishing swine.

This study was designed to evaluate growth performance, carcass cutting yield, and processing characteristics of boneless hams and bellies from finishing pigs fed diets containing 0, 5, 10, or 20 ppm of the phenethanolamine ractopamine hydrochloride (RAC). Sixty pigs were blocked by starting weight and randomly assigned to pens (four pigs/pen) within each of three blocks. Treatments were then randomly assigned to the pens to total six pens of the 0-ppm level and three pens each at the 5-, 10-, and 20-ppm RAC levels. Weight gain and feed consumption were monitored and animals were slaughtered by weight block after approximately 48 d on trial. Slaughter weight, ADG, and feed/gain were improved (P less than .05) for RAC treatments. Dressing percentage was higher and increased linearly (P less than .05) for RAC treatments. Carcass weight, length, leaf fat weight, backfat thickness, loin eye area, and color, marbling, and firmness of the longissimus were evaluated. The RAC-treated carcasses were heavier (P less than .05) and loin eye area increased linearly (P less than .05). One side of each carcass was fabricated using National Association of Meat Purveyors specifications. Trimmed hams and loins from the RAC treatments were heavier (P less than .05) than those from control animals. No differences (P greater than .05) in carcass cutting yield (percentage of trimmed primal cuts) were observed between treatments. However, trimmed hams and loins from the 20-ppm RAC treatment represented a greater (P less than .05) percentage of carcass weight than did those from control animals. Ractopamine did not affect raw belly or bacon characteristics (P less than .05).(ABSTRACT TRUNCATED AT 250 WORDS)     

Effect of dietary soybean meal on the microscopic anatomy of the small intestine in the early-weaned pig

Two experiments were conducted to determine the effect of soybean meal in postweaning diets on villus height (VH), villus shape and lamina propria depth (LPD) in the small intestine. Intestinal samples were taken at 25, 50 and 75% of the small intestine's length. The first experiment determined the normal effects of age on these structures in nursing pigs from 9 to 36 d of age. Villus height decreased (P less than .01 at the 50 and 75% locations) and LPD increased (P less than .01 at the 25% location) in a quadratic fashion with increasing age. In the second experiment, pigs were weaned at 21 d of age and fed one of three 20% protein diets: 1) protein from hydrolyzed casein (CAS), 2) soybean meal (SBM) or 3) a conventional corn-soybean meal diet (CSBM). Intestinal samples were taken 0, 3, 6, 9, 12 and 15 d post-weaning. Villus height decreased dramatically the first 3 d postweaning, with a continuing decline until 12 d post-weaning. Averaged over the d 3 to 15 interval, VH were generally greater for pigs fed CAS than for pigs fed CSBM or SBM. Pigs fed SBM or CSBM had deformed villi, and pigs fed SBM had greater (P less than .05) LPD at all intestinal locations, suggesting less mature enterocytes on the villi. These data suggest that feeding high concentrations of soybean meal to the pig post-weaning has a detrimental effect on the small intestine, but this effect was minimized when soybean meal was fed as part of a corn-based diet.     

吡啶羧酸铬和天冬氨酸镁对猪肉品质的影响

选择48头体重接近(86.0±5.1)kg的杜长大肥育阉公猪,研究天冬氨酸镁和吡啶羧酸铬对猪宰前应激肉品质的影响。试验猪分为4组,Ⅰ组为对照组,Ⅱ、Ⅲ、Ⅳ组为试验组,每组3个重复,每个重复4头,采食玉米-豆粕型日粮(DE,13.18MJ/kg;CP,14.6%)。Ⅰ组饲喂基础日粮;Ⅱ组饲喂基础日粮+1.0%天冬氨酸镁(MgAsp);Ⅲ组饲喂基础日粮+0.3mg/kg吡啶羧酸铬(Crpi);Ⅳ组饲喂基础日粮+1.0%MgAsp+0.3mg/kgCrpi。每头猪每日饲喂2.8kg上述试验日粮,7d后运到屠宰场。结果表明,日粮中补充吡啶羧酸铬、天冬氨酸镁、吡啶羧酸铬+天冬氨酸镁均降低了血清中皮质醇含量,减缓了屠宰前的应激反应;给宰前的育肥猪补充吡啶羧酸铬、吡啶羧酸铬+天冬氨酸镁均可降低宰后糖原分解(P0.05),补充天冬氨酸镁也有降低宰后糖原分解的趋势。补充吡啶羧酸铬、天冬氨酸镁及吡啶羧酸铬+天冬氨酸镁均可显著降低宰后短时间内猪背最长肌和股二头肌乳酸含量(P0.05);日粮中补充吡啶羧酸铬、天冬氨酸镁及吡啶羧酸铬+天冬氨酸镁均可极显著(P0.01)降低背最长肌和股二头肌pH和滴水损失,分别降低PSE肉发生率75.1%、49.8%和75.1%(P0.05),而对系水力无显著影响(P0.05));复合添加吡啶羧酸铬、天冬氨酸镁组猪的滴水损失、背最长肌和股二头肌色值都显著低于单独添加吡啶羧酸铬、天冬氨酸镁组,这说明吡啶羧酸铬、天冬氨酸镁在改善肉质指标方面具有一定的加性效应,二者同时添加效果最好。