Improving the lean muscle color of dark-cutting beef by aging, antioxidant-enhancement, and modified atmospheric packaging.

The objective was to evaluate the effects of wet-aging, rosemary-enhancement, and modified atmospheric packaging on the color of dark-cutting beef during simulated retail display. No-roll dark-cutting strip loins ( = 12; pH > 6.0) were selected from a commercial packing plant within 3 d postharvest. Using a balanced incomplete block design, dark-cutting loins were sectioned in half, and assigned to 1 of 3 aging periods: 7, 14, or 21 d. After respective aging, each aged section was divided into 3 equal parts, and randomly assigned to 1 of 3 enhancement treatments: nonenhanced dark-cutting, dark-cutter enhanced with 0.1% rosemary, and dark-cutter enhanced with 0.2% rosemary. Following enhancement, steaks were randomly assigned to 1 of 3 packaging treatments: high-oxygen modified atmospheric packaging (HiOx-MAP; 80% O and 20% CO), carbon monoxide modified atmospheric packaging (CO-MAP; 0.4% CO, 69.6% N, and 30% CO), and polyvinyl chloride overwrap (PVC; 20% O). Instrumental and visual color measurements were recorded during 5 d simulated retail display. Lipid oxidation was determined utilizing the thiobarbituric acid reactive substances (TBARS) method. There was a significant packaging × enhancement × display time interaction for values and chroma ( 0.001). On d 0 of display, dark-cutting steaks enhanced with 0.1% and 0.2% rosemary and packaged in HiOx-MAP had greater ( 0.001) values and chroma than other dark-cutting packaging/enhancement treatments. A significant packaging × enhancement × display time interaction resulted for values ( 0.001). Dark-cutting steaks enhanced with 0.2% rosemary and packaged in HiOx-MAP was lighter ( 0.001; greater values) than other dark-cutting treatments on d 5 of display. There were no differences ( 0.34) in discoloration scores on d 5 among different dark-cutting treatments when steaks were packaged in HiOx- and CO-MAP. There was an aging period × enhancement × packaging interaction ( < 0.0033) for lipid oxidation. On d 0 of display, there were no differences ( 0.54) in TBARS values between different aging periods and enhancement treatments. Dark-cutting steaks enhanced with 0.2% rosemary had lower ( 0.001) TBARS values than 0.1% rosemary on d 5 when aged for 21 d and in HiOx-MAP. The results suggest that rosemary enhancement with CO- or HiOx-MAP has the potential to improve the surface color of dark-cutting beef.

Isolation, selection, and characterization of lactic acid bacteria for a competitive exclusion product to reduce shedding of Escherichia coli O157:H7 in cattle.

Lactic acid bacteria (LAB) were selected on the basis of characteristics indicating that they would be good candidates for a competitive exclusion product (CEP) that would inhibit Escherichia coli O157:H7 in the intestinal tract of live cattle. Fecal samples from cattle that were culture negative for E. coli O157:H7 were collected. LAB were isolated from cattle feces by repeated plating on deMan Rogosa Sharpe agar and lactobacillus selection agar. Six hundred eighty-six pure colonies were isolated, and an agar spot test was used to test each isolate for its inhibition of a four-strain mixture of E. coli O157:H7. Three hundred fifty-five isolates (52%) showed significant inhibition. Seventy-five isolates showing maximum inhibition were screened for acid and bile tolerance. Most isolates were tolerant of acid at pH levels of 2, 4, 5, and 7 and at bile levels of 0.05, 0.15, and 0.3% (oxgall) and were subsequently identified with the API system. Lactobacillus acidophilus, Lactobacillus fermentum, Lactobacillus delbreukii, Lactobacillus salivarius, Lactobacillus brevis, Lactobacillus cellobiosus, Leuconostoc spp., and Pediococcus acidilactici were the most commonly identified LAB. Nineteen strains were further tested for antibiotic resistance and inhibition of E. coli O157:H7 in manure and rumen fluid. Four of these 19 strains showed susceptibility to all of the antibiotics, 13 significantly reduced E. coli counts in manure, and 15 significantly reduced E. coli counts in rumen fluid (P < 0.05) during at least one of the sampling periods. One of the strains, M35, was selected as the best candidate for a CEP. A 16S rRNA sequence analysis of M35 revealed its close homology to Lactobacillus crispatus. The CEP developed will be used in cattle-feeding trials.

The effect of dietary wheat middlings and enzyme supplementation. 1. Late egg production efficiency, egg yields, and egg composition in two strains of Leghorn hens.

A study was conducted to test the effects of wheat middlings (WM) with and without enzyme (xylanase and protease) supplementation on late egg production (EP), egg yields, and egg composition in two strains of Leghorn hens (DeKalb Delta and Hisex White). Six diets were randomly assigned to 300 birds (150 birds per strain) from 42 to 60 wk of age. Diet 1 was a corn-soybean meal control, Diets 2 and 3 had 8 and 16% WM, respectively, Diet 4 had 8% WM with 0.1% enzyme, and Diets 5 and 6 had 16% WM with 0.1 and 0.2% enzyme, respectively. Each dietary treatment was replicated five times per strain. Egg production, feed consumption (FC), feed efficiency (FE), percentage dirty eggs, specific gravity (SP), egg weight (EW), and egg mass (EM) were measured on a weekly basis. Egg components (EC) were measured biweekly and birds were weighed every 4 wk. Egg production was not significantly affected by diet, with averages of 83.7, 85.7, 84.1, 84.2, 82.3, and 84.0% for Diets, 1, 2, 3, 4, 5, and 6, respectively. Strain had a marked effect on FC, with Hisex having higher FC than DeKalb hens. Feed consumption also showed a significant diet by strain effect, being lower for Hisex hens fed diets with enzyme compared to diets without enzyme. DeKalb hens had better FE than Hisex hens, and addition of enzyme to 16% WM improved it further. Strain and diet had a significant effect on EC with higher percentages of albumen and yolk for diets with enzyme and for DeKalb hens. Percentage shell was lower for DeKalb hens than for Hisex hens but was not affected by diet. There was also a significant increase in EW for Diets 4 (63.1 g), 5 (63.8 g), and 6 (63.2 g) compared to Diets 1 (62.1 g), 2 (62.4 g), and 3 (63.0 g), with DeKalb hens showing an increase with Diet 5 compared to Hisex hens. Egg mass improved with the higher rate of enzyme in 16% WM diet compared to the lower enzyme level. Specific gravity declined with enzyme supplementation in WM diets. Eggs from DeKalb hens had lower SP than those from Hisex hens for all diets. Percentage dirty eggs did not differ significantly among treatments but was higher for the Hisex strain than for the DeKalb strain. There were no differences in BW between the two strains of hens or among diets. Adding protease and xylanase to diets rich in fiber can improve the egg output without affecting production parameters.

The effect of dietary wheat middlings and enzyme supplementation II: apparent nutrient digestibility, digestive tract size, gut viscosity, and gut morphology in two strains of leghorn hens.

An experiment was conducted with two strains of Leghorn hens, DeKalb Delta (D) and Hisex White (H), to investigate the effect of a commercial poultry enzyme preparation (EZ; xylanase plus protease) on the digestibility of protein, fat, Ca, and P and to determine any changes in the relative size of the digestive tract, gut morphology, and gut viscosity (GV) of birds fed wheat middlings (WM) over an 18-wk period. Three hundred birds (150 birds per strain) were randomly assigned to six diets: Diet 1, control (corn-soybean); Diets 2 and 3, 8% and 16% WM, respectively; Diet 4, 8% WM and 0.1% enzyme (EZ); and Diets 5 and 6, 16% WM and 0.1% and 0.2% EZ, respectively. There were five replicates per diet per strain. At 50 wk, protein digestibility increased significantly with supplementation of EZ, but, at 60 wk, all responses were similar. Protein digestibility was greater in DeKalb Deltas for WM with EZ compared with Hisex on the same treatment. Fat digestibility was greater for Diet 1 than the other diets at 50 wk but showed a similar response at 60 wk. The H strain showed a reduction in fat digestibility with WM diets with EZ. The control diet showed greater Ca digestibility than the other diets at 50 wk but did not differ at 60 wk. Phosphorus digestibility increased significantly for WM diets with or without EZ at 60 wk. Intestinal weight was significantly higher for WM with or without EZ at 50 wk, but was equal to the control diet at 60 wk. At 60 wk, gizzard weights (GW) were also lower in birds fed WM and WM with EZ compared with birds fed the control, but GV was not affected by dietary treatments. Histological observations on jejunum of birds fed WM without EZ showed shortening, thickening, and atrophy of the villi, all of which improved when EZ was included in the diet. Availability of some nutrients in WM diets was improved with supplementation of enzyme. Gastrointestinal (GI) tract and organ size were increased, and gut morphology appeared to be improved.

Strain and age effects on egg composition from hens fed diets rich in n-3 fatty acids.

A trial was conducted to study the effects of strain, age, and diet on egg production, egg composition, and yolk fatty acid incorporation. Three strains (six pens of eight hens per strain), [DeKalb Delta (D); Babcock B 300 (B); and Hy-Line W-36 (H)], were subjected to a 10% flax diet + oats from 30 to 50 wk of age. At 50 wk, hens were divided into two groups and one half were kept on flax + oats diets (three pens) or assigned to a second diet of flax - oats (three pens) to 60 wk of age. Eggs were collected at 36 and 58 wk of age for fatty acid and lipid analysis. Strain had an early effect (30 to 50 wk) on egg production with B (85.3) exceeding the other two strains D (81.0) and H (79.1). Strain D had greater feed consumption and egg weight than either B or H. Flax - oats increased percentage shell compared to flax + oats. Strain effect was significant for percentage albumin, which was greatest for D (61.2%) vs H (59.5%) and B (59.4%). Strain D had significantly lower total and percentage yolk lipids than the other two strains. Strain B eggs had more C16:0, but less C18:0 and C18:1 than D and H. No significant effect of strain on C18:2, C18:3, and C22:6 deposition was observed. Percentage C18:0 and C18:1 in the yolk was significantly affected by strain, diet, and strain x diet interaction. Dietary flax + oats increased C18:0 and C18:1 in all strains except H. A significant diet by strain interaction effect occurred such that C18:3 increased in D yolk but decreased in B yolk when flax + oats were fed. Deposition of C18:3 was greater at 58 wk (5.61%) than at 36 wk (2.52%) of age across all strains. Results from these trials indicate that strain, diet, and age can affect yolk lipids and composition.