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Electrical stimulation of beef carcasses did not cause a significant reduction in surface microbial population at three different sampling positions immediately following slaughter. However, significant microbial reduction (P

Crude calcium-activated factor (CAF) was prepared from pre-rigor pressurized (PRP) and corresponding control (CON) bovine muscles at 0, 1, and 3 days of postmortem times. Throughout these periods, PRP samples had consistently lower total CAF activity than CON. Yet, it seems probable that PRP caused a transient increase in Ca++ sufficient to activate CAF for a brief period of time because (1) early postmortem, PRP muscle had quantities of a 95,000-dalton component presumably produced by CAF; (2) Z-lines from at-death PRP muscles were highly degraded; (3) very early postmortem storage, the SDS-electrophoretic patterns of PRP myofibrils resembled that of CAF-treated myotibrils. CAF autolysis may account for the low CAF activity observed in PRP muscles at later postmortem storage times.

Puberty, cycling, ovulation, conception and embryo survival were determined for gilts managed by a specific regimen in confinement. At weights of 70 to 80, 91 to 100 and 109 to 116 kg (groups A, B, C, respectively) gilts were (1) moved from rearing pens to pens in a separate broodstock building, (2) housed in groups of eight to 10 with unfamiliar penmates and (3) exposed to boar presence in an adjoining pen. Groups A and B were mated at third estrus; group C was mated at first estrus. For the three groups 76, 79 and 79%, respectively, of allotted gilts mated; of these 21, 13 and 11%, respectively, showed estrus again and were remated. Ten, 10 and 11%, respectively, were not pregnant when slaughtered at 25 to 28 d of postmating. Average days on experiment to first estrus were 14, 15 and 16 for groups A, B and C; mean interval between estrous periods was 21 d. Ovulations (13.3, 12.9 and 12.6) and live embryos (11.6, 11.1 and 10.7, respectively) did not differ significantly among groups. None of the reproduction traits were significantly associated with differences in mean age or weight among the three groups at breeding.(ABSTRACT TRUNCATED AT 250 WORDS)

A 2x2 factorial experimental design with 2 replications was used to study the effects of a combination of electrical stimulation and delayed chilling of carcass on meat characteristics. Twenty Standard or Good grade beef cattle were slaughtered and 10 sides were assigned to each of the 4 treatments. Meat characteristics were evaluated subjectively (sensory panel evaluation) and objectively (W-B shear device). Electrically stimulated carcasses cooled faster in the first hour postmortem; thereafter the order of further cooling was reversed. The 24 hr postmortem weight loss in the electrically stimulated with delayed chilling did not differ (P > 0.05) from those receiving electrical stimulation plus immediate chilling nor those not stimulated but chilled immediately. For delayed chill carcasses, 24 hr postmortem weight loss was lower (P 0.05). At the microstructural level, an open triad and T-system were observed immediately following electrical stimulation. As early as 24 hr postmortem, considerable Z-line degradation was observed in the electrically stimulated and delayed chilled samples.

Summary The response of growing-finishing swine to high levels of dietary alfalfa meal was examined. In trial 1, pigs were fed barley-based diets containing 0, 20, 40 or 60% alfalfa meal. Average daily gain (ADG) was reduced and feed/gain increased (P

Sixty single-reared lambs sired by Hampshire rams were used to study the effects of monensin and ryegrass straw on feedlot performance. Two levels of monensin (0 and 27.5 ppm) and two levels of ryegrass straw (0 and 25%) were arranged in a 2 × 2 factorial treatment arrangement. Each of the four pelleted diets was fed ad libitum to 15 lambs. Monensin-fed lambs had lower (P 0.10), monensin-fed lambs also had improved feed efficiencies over lambs not fed monensin. Crude protein, ether extract and crude fiber digestibilities of the diets were increased by the addition of monensin. Lambs fed ryegrass straw had lower (P

The response of growing pigs receiving a low energy diet (LE ration) to periodic exposures to a high energy diet (HE ration) was studied. Forty-eight Berkshire × Yorkshire barrows of approximately 23 kg body weight were divided into six equal groups receiving one of the following treatments: HE control, LE control, and alternations between the LE and HE rations in cycles of 5 days LE: 1 day HE. 4 days LE: 1 day HE, 3 days LE: 1 day HE, and 2 days LE: 1 day HE. The average daily gain of the HE control was significantly greater (P

The effect of hydrostatic pressurization of pre-rigor beef round muscle (semitendinosus) on protein quality was biologically and chemically determined. For biological evaluation rats (Long-Evans strain) were used. Chemical evaluation was carried out by amino acid analysis. The biological and chemical protein efficiency ratios (PER) of pressurized meat were 2.47 and 2.7, respectively, compared to 2.60 and 2.84 for the control meat. Pressurization did not affect the apparent biological value (BV) or net protein utilization (NPU) of meat but significantly (P < 0.05) improved protein digestibility. Total essential and nonessential amino acid contents of pressurized samples were not different from that of the control. At the range tested, the protein quality of meat was not adversely affected by pressure treatment.

One randomly selected side from each of ten beef carcasses was hot boned and subjected to hydrostatic pressurization (103.5 MNm/sup -2/) for 2 min; the corresponding control sides were cold boned at 48 hr. Twelve boneless wholesale beef cuts were removed from each side and evaluated for boning yields, purge loss, wholesale cut yields, and trimmed retail cut yields. No significant differences were found in yield of bone, fat, or lean trim between hot- and cold-boned sides, nor was there any difference in purge loss between the 12 control and pre-rigor pressurized (PRP) boneless wholesale cuts (P > 0.05). There was a higher (P 0.05) in total trimmed retail yield between conventional (control) and hot-boned PRP sides.

The emulsifying capacities of pressure treated and control muscle homogenates, sarcoplasmic protein and myofibrillar proteins of ovine and bovine longissimus muscles were determined at 2, 6, 24 and 168 hr postmortem. The pH of the intact muscle, muscle homogenate and myofibrillar protein extract were taken at these times. Before onset of rigor mortis, the emulsifying capacity of muscle homogenate from the control samples was higher than the pressure treated samples. At 24 and 168 hr postmortem, the pressure treated and control samples were not significantly different (P>0.05) for emulsifying capacity. At 2 hr postmortem, the emulsifying capacity of myofibrillar protein extract from control samples was higher (P

Semimembranosus muscle was excised immediately following slaughter and pressurized at 103.5 MN−2 for 2 min at 35°C. Creatine phosphate (CP), adenosine-5′-triphosphate (ATP) and R-values (a measure of metabolic rate) were determined at 1, 2, 4, and 24 hr postmortem. Creatine phosphokinase activity (CPK) was measured at 1 and 24 hr postmortem. Pressurization accelerated catabolism of both CP and ATP which, in turn, resulted in a higher ATP turnover value than that of the control. R-values were significantly correlated (r=−0.95) with degradation of ATP and indicate onset of rigor mortis in treated muscle immediately after pressurization. CPK activity was significantly higher (P

SUMMARY –Paired short loins from carcasses representing five degrees of marbling, slight through slightly abundant, were randomly assigned one from each pair to air and vacuum aging in a 35°F cooler before cutting into New York steaks and prepackaging for display. Half of the packaged steaks were held in a dark cooler at 35 ± 2°F for 24 hr before being placed in a lighted, open-top display case; the orher half was put immediately into the display case. Color description and color desirability of all steaks were evaluated daily by a three-member panel. Case life was terminated when a visible spot resulting from formation of metmyoglobin appeared on the surface of the meat. Vacuum-aged short loins had a higher yield of trimmed retail cuts than air-aged short loins. There was no difference in case shrink attributable to type of aging. The steaks held in a dark cooler for 24 hr had 23.8 hr less case life than those put immediately into the lighted display case. Degree of marbling had a significant positive linear effect on color description scores at 24 and 48 hr post-cutting, but did not affect color desirability score. Marbling had a significant curvilinear effect on case life with slight (the least) and slightly abundant (the greatest) amounts having the shortest case life.

Myofibrils were isolated from the longissimus (L) muscle of control (CON) and cold-shortened (CS) muscles after 0, 1, 3, 7, and 10 days of postmortem storage at 2°C. Isolated myofibrils were then examined by SDS-polyacrylamide gel electrophoresis to monitor the changes in the myofibrillar proteins during postmortem storage. The main changes in CS muscles were the gradual appearance of 110,000-, 95,000-, and 30,000d-dalton components and the disappearance of desmin and troponin-T components of myofibrils. In addition, there was a gradual increase in the intensity of a protein around 55,000-daltons. CON samples showed similar changes to those of CS samples. It appears that myofibrillar proteins of cold-shortened muscles are affected by postmortem aging in a manner similar to that of the normally chilled muscles.

Prerigor bovine semimembranosus muscle was pressure-treated at 103.5 MNm-2 (15.000 psi) for 2 min at 37°C. Glycogen levels of pressurized muscle were significantly (P < 0.01) lower than those of the control at 1, 2 and 4 hr postmortem. Glucose concentrations were significantly (P < 0.01) higher in the treated muscle than in the control at all sampling periods. Lactate content increased rapidly after pressurization (1 hr postmortem); however, there was no significant difference between control and treated muscles at 24 hr. Pressurized muscle showed a significant (P < 0.01) increase in LDH activity over that of the control muscle at 1 hr, but not at 24 hr postmortem. Thus pressurization of muscle accelerated the rate of glycolysis and enhanced LDH activity.

Loin steaks were obtained from eight utility cows and ground beef from the bottom round of four choice steers. One side was randomly assigned to be prerigor pressurized (PRP) and the other side served as control (CON). Steaks and ground beef were displayed under simulated retail conditions for 5 and 3 days, respectively. PRP significantly improved lean color of the steaks for the first 4 days of display period. PRP steaks were significantly less discolored at the 5th day. No significant difference for any of the measured traits was observed for samples of ground beef. PRP had no detrimental effect on the case-life of steaks or ground beef.

Changes in myofibrillar proteins of bovine longissimus and semitendinosus muscles were examined during 14 days of postmortem storage at 2°C by SDS-Polyacrylamide gel electrophoresis. Major changes in both muscles were: (1) appearance of a 95,000-dalton component; (2) gradual disappearance of troponin-T and gradual appearance of a 30,000-dalton component; (3) gradual increase in intensity of a protein around 55,000-daltons; and (4) gradual appearance of a 110,000-dalton component. With the exception of the 95,000-dalton component, the other changes have been reported previously by other authors. At the present time we have no knowledge of the origin of the 95,000-dalton component, but it is known that calcium-activated factor (CAF) is responsible for degradation of troponin-T. Appearance of the 95,000-dalton component during postmortem storage suggests involvement of CAF for increasing tenderness during postmortem storage.