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Describes the development of a computer simulation model of forage-beef production systems, which is intended to incorporate soil, forage, and animal decisions into an enterprise scenario. Produces a summary of forage production and livestock needs. Cites positive assessment of the program's value by participants in inservice training workshops. (TW)

A survey was made of commercially available vacuum-packaged fresh pork held at 5 C for 7, 14, 21 and 28 days. Also, four vacuum-packaged leg roasts were stored for 21 days at 5 C then for 90 days at -18 C before sampling. Surface cores of meat were enriched in sorbitol bile broth 21 days at 5 C to enhance recovery of Yersinia enterocolitica on pectin agar. Of the 54 samples surveyed, 20% yielded highly pectinolytic colonies of Aeromonas hydrophila that were cytotoxic to Y1 and HeLa cells, 6% yielded Y. enterocolitica and 6% yielded Yersinia intermedia . Yersinia was recovered from both fresh and frozen samples. This is believed to be the first report of pectinolysis by A. hydrophila and recovery of cytotoxic A. hydrophila from vacuum-packaged pork.

Viable counts of bacteria are often high in some areas and low in adjacent areas of the same surface of fresh meat. The present study indicated that rubbing meat surfaces together before sampling reduces variation among bacterial plate counts of pieces of beef plate meat. Counts before rubbing ranged from 2 to 6,187/cm 2 , whereas counts after rubbing ranged from 15 to 2,043/cm 2 . The reduced sample variance allowed for fewer samples to be taken in studies of cleaning and sanitizing of fresh beef.

Strips of plate meat were sprayed with acetic acid, sodium hypochlorite, or tap water after they were washed with 0, 12.7, or 25.4 liters of tap water/min. Washing before sanitizing lowered bacteria counts significantly only when the higher volume of water, 1.4 ml/cm 2 , was applied, and this difference existed for samples taken immediately but not 48 h after treatment. Reductions in counts exceeded 99.9% when samples washed with 25.4 liters/min (1.4 ml/cm 2 ) were sanitized with 3% acetic acid. This sanitizer was sprayed at the rate of 6.8 liters/min (1.9 ml/cm 2 ) at a pressure of 14.0 kg/cm 2 from a distance of 40 cm as the meat moved at 2 cm/sec through the spray. Under comparable conditions of application, both sodium hypochlorite (200 to 250 mg/liter) and tap water reduced counts by about 90%. Acetic acid had a much greater residual effect on numbers of viable bacteria than did hypochlorite. No effect of air drying was observed.

Growth of Pseudomonas fragi had a significant (P < .05) effect on the color of aqueous beef extract stored at 1 ± 1 C. As numbers of P. fragi increased from log 5 to 7.9/ml during 10 days of storage at 1 ± 1 C, the pH increased from 5.5 to 6.0. At the end of 10 days there was a 76% loss of oxymyoglobin in samples inoculated with P. fragi . There was a 45% loss of oxymyoglobin in sterile-control samples. A possible mechanism for conversion of oxymyoglobin to metmyoglobin is suggested.

Our previous studies suggested the need to study absorption and evaporation of water from meat during cleaning with water sprays. This article describes the effects of type of meat surface, line pressure, size and configuration of nozzle, and speed of meat travel past the nozzle on water absorption and percent shrinkage after 24 h. Cut meat surfaces had a higher percent gain and lower percent shrinkage than did uncut surfaces. Pressure had no significant effect on percent shrinkage. Solid stream nozzles caused a higher percent gain and a lower percent shrinkage than did flat fan nozzles. As the size of the nozzle was increased, the percent gain increased and the percent shrinkage decreased. The slowest speed of meat travel past the nozzles (5 cm/s) caused the highest percent gain in weight.

Plate beef was washed and/or sanitized with cold water, hot water, steam, sodium hypochlorite, or acetic acid before being stored for up to 28 days at 3.3 C and 90% relative humidity. Microbial counts initially and at regular intervals thereafter disclosed that, compared with untreated controls, time to reach counts of 10 8 bacteria per cm 2 were (a) 1 day less with steam- or water-treated samples, (b) 2 to 3 days more with hypochlorite-treated samples, (c) 5 days more with hot-water-treated samples, and (d) 16 to 17 days more with acetic acid-treated samples. Re-sanitization with acetic acid extended time to reach equivalent counts by 7 additional days.

An experimental cleaning and sanitizing unit was used in cleaning and sanitizing (3.0% acetic acid) beef carcasses. It cleaned the carcasses sufficiently that they would pass the Acceptable Quality Level test of the Food Safety and Quality Service, U.S. Department of Agriculture. The sanitizing unit reduced the microbial population on the surface of the meat by an initial 1.49 logs; the difference between washed and washed and sanitized carcasses after 1 week (168 h) was 0.92 log. A slight gray cast developed within the top 1 mm of fat almost immediately after the acid was applied. Sensory panel members detected no adverse effects on the lean portion of steaks from sanitized carcasses. However, they detected a slight off-flavor in treated fat.

Thirty multiparous cows rotationally grazed high quality grass pastures (predominantly Dactylis glomerata and Poa pratensis) for 140 days. Stage of lactation was 54 to 192 days at beginning of trial. Cows were offered concentrates to supply 33, 66, or 100% of requirements for net energy for lactation above maintenance; daily intakes by the three groups averaged 3.5, 7.7, and 11.5 kg. Refusal of concentrate tended to increase with supplementation. Average milk production was 19.2, 20.4, and 21.5 kg. When individual yields were compared with an initial 2-wk period prior to trial, there was no difference in decline in milk flow, except for one 28-day period in midsummer when decline by the 33% group was greater than that by the 100% group. Milk fat yields were similar. Milk protein yields by the 100% group were significantly higher than those by the 33% group. Body weight changes were similar among groups. Quality of forage was high, and yields were adequate. Changes in milk flow attributable to movement of cows to fresh pastures were +1.35 kg per cow daily. Variations in in vitro dry matter disappearance, crude protein, and dry matter of forage were positively associated with changes in milk flow.

Eighty half carcasses were either: (a) hand-washed with tap water (15 C) or (b) washed (15 C) with an experimental beef carcass cleaning unit. Overall logarithmic mean reduction in aerobic plate counts were 0.99 for hand-washed carcasses and 1.07 for those machine-washed. No significant difference (P ⩽ 0.05) was noted in percentage dirt and smear reductions due to type of wash (hand or machine). However, 12.5% of the hand-washed carcasses and 22.5% of the machine-washed carcasses contained defects caused by hair. The authors concluded that the machine was at least as effective as the careful hand washing in this experiment.

Beef was stored aerobically for 2 or 6 d at 1 ± 1°C before vacuum packaging. Total numbers of aerobic bacteria, Pseudomonas spp., Brochothrix thermosphacta and lactic acid bacteria were determined by selectively plating stored samples. Meat color was evaluated with a color difference meter and a color panel. Aerobic plate counts, numbers of pseudomonads and B. thermosphacta , and pH each were higher in samples held aerobically for 6 d compared with those held aerobically for 2 d. The major effect of delayed vacuum packaging was to slow the growth of lactic acid bacteria and minimize the number of pseudomonads. The variation among treatments was similar in Pseudomonas spp. population for 21 d and in pH for 7 d, and there was no significant effect of packaging treatment in color. Results indicate that the initial treatment variations were lost as storage time progressed.

Our objective was to develop basic design criteria for use in fabricating a functional chamber for a red meat carcass cleaning unit. Emphasis was placed on eliminating the doors. A model carcass cleaning chamber was constructed to test effects of selected design parameters on direction and velocity of airflow. Based on data from the tests using the model, a full-scale chamber with no doors was designed, fabricated, and installed in a commercial packing plant for testing. The air moves into the chamber at both the entrance and the exit. This movement of air into the chamber prevents water droplets entrained in the air from escaping into the slaughtering area and causing condensation on the walls and roof.

An automated device for spray-type cleaning-in-place of a beef carcass washer constructed of linear polyethylene was evaluated by microbiological tests. Swabbing of seams at the welded joints, followed by plating of the swab rinse solution, disclosed that cleaning reduced counts by more than 99%. The average number of microorganisms recovered from seams after cleaning was 80/cm 2 . However, it was necessary also to manually clean certain joints weekly. Flat surfaces were quite adequately cleaned according to results of tests with RODAC plates. With RODAC plates, numbers of yeasts and molds recovered on potato dextrose acid agar were better indicators of sanitary condition than numbers of coliforms on violet red bile agar or numbers of staphylococci on Baird-Parker agar.

The bacteriology of boneless pork loins that were either spray-washed (SW) with water, spray-washed and sanitized with a 200 ppm sodium hypochlorite solution (SSCL) or spray-washed with water and sanitized with a 2% acetic acid solution (SSAA) before being vacuum packaged and stored for up to 28 d at 4.0°C was studied. Aerobic, anaerobic and lactobacilli bacterial counts immediately after treatment and at 14, 21 and 28 d were significantly lower on loins receiving the SSAA treatment than loins receiving the SW and SSCL treatment. SSCL loins had lower bacterial counts than untreated controls during 14 d of storage. SW loins had significantly lower bacterial counts than control loins only immediately after treatment. The SSAA treatment resulted in some discoloration. If this discoloration can be prevented, this treatment should be useful in extending the storage life of fresh pork.

Beef plate meat was sprayed with sodium hypochlorite (pH 6.0) from two sources, commercial and electroytically generated. Variables studied in two experiments were rate of flow of sanitizer, line pressure, speed of movement of meat through the sprays, and method and time of sanitization. Hypochlorite sprays reduced microbial counts significantly more than did water applied under the same conditions, but type of hypochlorite was unimportant. Maximum reductions in counts made immediately after sanitization approximated 97 and 93% as measured by swab and core sampling methods, respectively. Sprays were most effective when delivered in a single passage over meat at a rate of 2 rather than 10 cm/sec or in about seven successive passages at 10 cm/sec. Samples collected by coring and swabbing estimated microbial populations different from each other when the samples were taken after sanitized meat had been stored at 3 C for 48 h. Based on our findings we recommend the coring method.