Conjugated linoleic acid (CLA) was supplemented to crossbred growing-finishing barrows (n = 60) at 0.75% of the total diet. Pigs were randomly assigned to the CLA or control diets based on stress genotype (negative, carrier, or positive). Gain:feed was higher for CLA diet animals (350 g/kg feed) than for control diet animals (330 g/kg feed) independent of genotype (P < 0.05). No differences were observed for ADG for the diets (P = 0.71) or genotype classes (P = 0.40). Postmortem pH was lower (P < 0.01) by 3 h for CLA-supplemented pigs, with no differences in ultimate pH. No differences (P = 0.16) were observed for ultimate pH between the three genotypes. Conjugated linoleic acid-supplemented pigs exhibited less 10th rib fat depth (2.34 cm vs 2.84 cm) and last rib fat depth (2.46 cm vs 2.72 cm) than control pigs (P < 0.05). Loin muscle area (LMA) was not affected (P = 0.18) by CLA supplementation, but LMA was different (P < 0.02) for genotype; positive genotype carcasses had the largest LMA (45.02 cm2) and negative carcasses had the smallest LMA (36.44 cm2). Carrier carcasses were intermediate for LMA (40.76 cm2). Subjective scores for color were not affected (P = 0.98) by CLA but color was different (P < 0.01), with scores of 1.50, 2.40, and 3.1 for positive, carrier, and negative genotypes, respectively. Subjective marbling scores were increased (P < 0.03) in all genotypes with CLA supplementation. Subjective firmness scores were higher (P < 0.06) for CLA-supplemented pigs and were highly correlated (0.89) to marbling scores. The L* values were higher (P < 0.01) for stress-positive pigs at 24 h postmortem. Also, L* values were higher (P < 0.01) for CLA-fed pigs over 7 d of shelf storage. Sensory characteristics were not different with CLA supplementation for tenderness (P = 0.24), juiciness (P = 0.35), or flavor intensity (P = 0.14). This study showed that LMA was increased with stress-carrier and stress-positive genotypes, but lean color was negatively affected with the presence of the stress gene. Conjugated linoleic acid supplementation improves feed efficiency, decreases backfat, and improves pork quality attributes of marbling and firmness of the longissimus muscle. Furthermore, there is seemingly no interaction between the stress-genotype status of pigs and the subsequent effect of CLA on their growth and performance.

The objective of this experiment was to determine the effects of dietary lipid source with or without the addition of CLA on bacon composition and quality. Forty-eight barrows at a beginning BW of 55 kg +/- 2.2 were fed 1 of 6 diets for 56 d. These diets consisted of: 1) normal corn (NC), 2) NC + 1.25% CLA-60 oil (NC + CLA), 3) high-oil corn (HOC), 4) HOC + 1.25% CLA-60 oil (HOC-CLA), 5) NC + choice white grease (CWG; NC + CWG), and 6) NC + CWG + 1.25% CLA-60 oil (NC + CWG + CLA). The CLA-60 contains 60% CLA isomers in the oil, and therefore, 1.25% oil was needed to achieve 0.75% CLA in the diet. Soy oil replaced CLA in control diets. Choice white grease and high-oil corn were selected as fat sources for this study because of their utility in energy density for growing-finishing pigs, especially in hot weather. Pigs were slaughtered at an average BW of 113 kg +/- 4.1, and carcasses were fabricated at 24 h postmortem. Statistical analysis was performed using the mixed model procedure of SAS, and the main effects tested were dietary lipid source, CLA, and 2-way interaction. The addition of CLA to each basal diet improved (P < 0.05) belly firmness measured either lean side down or fat side down from the belly bar firmness test [4.39 cm vs. 7.01 cm (lean down) and 5.75 cm vs. 10.54 cm (fat down)] for 0 and 0.75% dietary CLA, respectively. The compression test used on bacon slabs showed that bacon from CLA-supplemented pigs was approximately 20% firmer than that from controls. Pigs fed the HOC diets had softer bellies compared (P < 0.05) with pigs fed the NC diet as measured by the belly bar test [6.94 cm vs. 9.26 cm (fat down)], respectively. Conjugated linoleic acid did not, however, improve bacon sliceability. No differences were observed for moisture, protein, or lipid percentages between any treatments. Overall, there was a CLA effect (P < 0.04) for lipid oxidation, in which the addition of CLA decreased bacon oxidation (0.1498 CLA vs. 0.1638 no CLA). Dietary CLA increased the percentage of SFA in tissues from pigs supplemented with CLA. Dietary inclusion of CLA increased the concentration of all measured isomers of CLA in bacon. Sensory scores of bacon showed no differences for any of the sensory attributes measured between any of the treatments. Our results indicate that inclusion of dietary CLA will improve belly firmness, extend the shelf life stability of bacon, and increase the degree of fat saturation.

Heavy sows (n = 126) were treated with penicillin G procaine at a 5× label dose (33 000 IU/kg) for 3 consecutive days by intramuscular (IM) injection using three patterns of drug administration. Treatments differed by injection pattern and injection volume. Sets of sows were slaughtered 5, 10, 15, 20, 25, 32, and 39 days after the last treatment; skeletal muscle, kidney, serum, and urine were collected for penicillin G analysis by LC-MS/MS. Penicillin G at withdrawal day 5 averaged 23.5 ± 10.5 and 3762 ± 1932 ng/g in muscle and kidney, respectively. After 15 days of withdrawal, muscle penicillin G residues were quantifiable in only one treated hog (3.4 ng/g) but averaged 119 ± 199 ng/g in kidneys. Using a hypothetical tolerance of 50 ng/g and a natural log-linear depletion model, the withdrawal period required for penicillin depletion to 50 ng/g was 11 days for skeletal muscle and 47 days for kidney.

The objective of this study was to examine the prevalence of Salmonella enterica in cull sows at various stages from the farm to the abattoir. Cull sows (n=181) were sampled over 10 weeks. Fecal samples (10 g each) were collected on the farm ca. 24 h before loading and at the live-hog market ca. 3 h before loading. Samples (ileocecal lymph nodes, cecal contents, feces from the transverse colon, ventral thoracic lymph nodes, subiliac lymph nodes, sponge swabs of the left and right carcass sections, and chopped meat) were collected at the abattoir. The percentages of positive fecal samples on the farm and at the live-hog market were 3% (5 of 181 samples) and 2% (3 of 181 samples), respectively. After transport from the live-hog market (10 h) and holding at the abattoir (6 h), 41% (74 of 180) of cull sows yielded S. enterica in one or more sampled tissues. The isolation rate for total cecal contents (33%; 60 of 180 samples) was significantly (P<0.05) higher than those for ileocecal lymph nodes (7%; 12 of 181 samples), feces (11%; 20 of 181 samples), and ventral thoracic and subiliac lymph nodes (2%; 4 of 181 samples). Before a 2% lactic acid carcass wash (lasting 8 to 9 s), 14% (25 of 180) of carcasses were positive, compared with 7% (12 of 179) after the wash (P<0.05). Two S. enterica serotypes, Derby and Infantis, were found on the farm and at the live-hog market. At the abattoir, 12 serotypes that had not previously been found on the farm or at the live-hog market were recovered. The results of this study demonstrate that transport and holding practices may contribute to an increase in S. enterica infection prior to slaughter to levels much higher than those found on the farm.

Sows (n = 126; 228 ± 30.1 kg) were administered daily IM doses of penicillin G procaine (33 000 IU/kg bw; 5× the label dose) for 3 consecutive days using three different administration patterns. Within treatment, six sows each were slaughtered on withdrawal day 5, 10, 15, 20, 25, 32, and 39. Tissues (injection site, kidney, liver, skeletal muscle) or body fluids (serum and urine) were screened for penicillin G using the KIS test, recently adopted by the USDA Food Safety and Inspection Service. The IM administration patterns had no discernible effect on penicillin G depletion. Residues were depleted more rapidly from liver and skeletal muscle and more slowly from kidney and urine. Kidney was the most sensitive and suitable tissue for detecting penicillin G residues on-site, with two positive results after a 39-day withdrawal period. Urine was the most suitable ante-mortem surrogate to predict the results of kidney tests.

This study was designed to compare Salmonella enterica prevalence in sows held in a holding pen at the abattoir for approximately 2 h (hold sows) with sows slaughtered immediately after transport to the abattoir (no-hold sows). Cull sows (n = 160) were sampled from four sampling periods over 8 weeks (February to March 2002) at the abattoir. Sows originated from an integrated swine farm and were sent to a live-hog market and then to the slaughter facility. Before testing, sows entered the abattoir pen and four 100-cm2 four-ply gauze squares were placed randomly on the pen floor for S. enterica culture. Sows were alternatively assigned to the hold or no-hold group. Samples collected from sows during slaughter were ileocecal lymph node, cecal contents, transverse colon contents, subiliac lymph node, sponge swabs of the left and right carcass section (300 cm2), and chopped meat. Overall, S. enterica was isolated from 44% (35 of 80) of the no-hold sows, which was significantly less (P < 0.05) than 59% (47 of 80) of the held sows. Also, no-hold sows had a lower cecal content prevalence (39%, 31 of 80) compared with that (55%, 44 of 80) of held sows (P < 0.05). S. enterica serovars isolated from no-hold sows were Brandenburg (n = 16), Derby (n = 12), Hadar (n = 8), Infantis (n = 6), Johannesburg (n = 3), 6,7:z10-monophasic (n = 3), and Typhimurium (n = 1). S. enterica serovars isolated from held sows (n = 61 isolates) were Derby (n = 19), 6,7: z10-monophasic (n = 15), Brandenburg (n = 10), Infantis (n = 6), Hadar (n = 5), Johannesburg (n = 4), and Tennessee (n = 2). Serovars recovered from the pen were Reading (n = 6), Derby (n = 4), Uganda (n = 2), and Manhattan (n = 2). Results of this study suggest that holding pens contribute to increased S. enterica carriage in cull sows. Abattoir holding pens might be an important control point for S. enterica in the ground pork production chain.

This study was designed to observe the effects of conjugated linoleic acid (CLA) supplementation on lean content of pork carcass primal cuts (hams, loins, and bellies) and to determine the ability of total body electrical conductivity (TOBEC) to predict lean content. A total of 64 crossbred growing-finishing barrows were placed on a control (soybean oil) or CLA (0.75%) diet at an average weight of 40 kg. Pigs were penned in pairs according to diet and stress genotype (negative, carrier, and positive) and slaughtered at 115 kg. Stress genotype was included because of known variations in lean content. Hams (IMPS 401A; n = 64), loins (IMPS 410; n = 24), and bellies (IMPS 408; n = 63) were fabricated from carcasses at 24 h postmortem and scanned for electromagnetic (EM) absorption by a MQ-25 EM scanner. Each wholesale cut was scanned in triplicate at 2.5 MHz to yield a peak mean average (PMA) value then separated into lean, fat, bone, and skin components. Bellies were skinned prior to scanning then subjected to a belly bar firmness test before dissection. Supplementation with CLA had no effect (P > 0.05) on lean ham composition. Regression analysis was used for lean weight prediction using primal weight and PMA value as predictors. Lean content prediction of hams by TOBEC resulted in an R2 of 0.80. Loins from CLA-supplemented pigs exhibited increased lean weight (P < 0.05) and PMA values (P < 0.05) compared to controls. Lean prediction of loins by TOBEC resulted in an R2 of 0.66. Bellies from CLA-supplemented pigs had a higher percentage of moisture (P < 0.03) and protein (P < 0.01) and decreased percentage of lipid (P < 0.01). The R2 values from the regression analysis predicting protein, moisture, protein + moisture, and fat-free soft tissue composition of the skinless bellies were 0.67, 0.68, 0.71, and 0.78, respectively.

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