Relationship of eggshell ultrastructure and shell strength to the soundness of shell eggs.

Factors affecting the soundness of shell eggs are of primary concern to egg processors due to substantial financial losses from cracked and leaker eggs. Ultrastructural analyses were used to examine the palisade layer width and mammillary knob layer thickness of sound, cracked, and leaker eggshells. Subjective observations were also made. There was no significant difference (P > 0.05) in the width of the palisade layer or the mammillary knob layer among sound, cracked, and leaker eggshells. The eggshell strengths of sound, cracked, and leaker eggs were evaluated using puncture force and shell thickness measurements. Sound eggshells were found to have a significantly (P < 0.05) higher mean puncture force (35.3 N) than cracked (30.4 N) and leaker (28.4 N) eggshells. The mean puncture force values for cracked and leaker eggshells were not significantly different from each other (P > 0.05). Regression and correlation analyses indicated a significant correlation (P < 0.01; r = 0.61) between palisade layer width and puncture force. The mean shell thickness values for cracked (0.36 mm) and leaker (0.35 mm) eggs were significantly lower (P < 0.05) than those of sound eggs (0.38 mm), although cracked and leaker eggshell thickness did not differ significantly (P > 0.05). The correlation coefficient between puncture force and shell thickness was significant (P < 0.01; r = 0.56), indicating a possible relationship.

The role of defeathering in the contamination of turkey skin by Salmonella species and Listeria monocytogenes.

This study was undertaken to determine whether the incidence of either Salmonella spp. or Listeria monocytogenes on turkeys at three commercial processors could be related to the type of defeathering system: 1) conventional, 58 C common bath scald; 2) kosher, 7 C common bath scald; or 3) steam-spray, 62 C nonimmersion scald. Flocks were sampled before defeathering, after defeathering, and after chill at each facility. The incidence of Salmonella-positive turkeys significantly increased subsequent to conventional defeathering (10 positive out of 14) as compared with before defeathering (3/14). The number of Salmonella-positive carcasses following kosher (0/14) and steam-spray (2/14) defeathering were similar to the number of Salmonella-positive carcasses found prior to defeathering (1/14 and 3/14, respectively). The incidence of Salmonella-positive carcasses following chill was slightly lower, but not significantly different than the number of Salmonella-positive carcasses found immediately following defeathering at all processors (8/14, 0/14, 1/14 for conventional, kosher, and steam-spray processors, respectively). Although L. monocytogenes was detected on turkeys sampled before chilling (2/10, kosher) and after chilling (8/14, kosher; 1/14, conventional), no L. monocytogenes was detected on turkeys at any of the processors prior to the evisceration process. Flocks with high aerobic plate counts prior to processing were more likely to contain Salmonella-positive birds throughout processing. Aerobic plate counts of all flocks were similar after chill whether or not Salmonella spp. and L. monocytogenes were detected.

Effect of type of defeathering system on Salmonella cross-contamination during commercial processing.

The cross-contamination effects of three commercial defeathering systems were compared using turkeys from a single Salmonella-positive flock (< or = 15% cloacal-positive). Single or "common" flocks were used to control flock-to-flock variability. Thirty birds were mechanically defeathered in each system as the first flock of the day and compared with 30 hand-defeathered (control) birds. Three trials, each using a different common flock, were completed. In Trial 1, the incidence of Salmonella-positive birds decreased following mechanical defeathering at all three processors. The incidence of Salmonella-positive carcasses in test flocks increased following steam-spray (approximately 100%) and kosher (approximately 50%) defeathering in Trials 2 and 3, whereas no increase in Salmonella-positive carcasses resulted from conventional defeathering. The decrease in the number of Salmonella-positive birds as a result of defeathering observed in Trial 1, as compared to increases observed in Trials 2 and 3, may be related to the selection of feather-contaminated (Trial 1) vs intestinal-colonized (Trials 2 and 3) turkeys. Surface temperature of the carcasses and length of time required to defeather were monitored within each system. It is hypothesized that the increases in the number of Salmonella-positive birds following steam-spray and kosher defeathering in Trials 2 and 3 were a result of skin surface changes occurring during the defeathering process, which allowed increased adherence or entrapment of Salmonella spp. on or within remaining skin layers.

Effect of feed withdrawal on composition and quality of broiler meat.

The effect of feed withdrawal or total withdrawal (simultaneous feed and water withdrawal) on the composition and quality of broiler meat was evaluated. Feed or water or both were withdrawn 0, 6, 12, or 18 h before slaughter. A gradual and significant (P less than .05) increase in weight loss was seen as hours of withdrawal increased. Overall, birds subjected to feed withdrawal treatments experienced a 3.8% shrinkage; birds on total withdrawal treatments lost 4.4% in body weight. Percentage of water uptake during chilling increased gradually as feed withdrawal time increased. Birds on total withdrawal absorbed water in this fashion until 18 h of chilling, when there was a sharp and significant drop in water uptake. No significant differences were found among treatments for precook and cooked weights, cooking loss, total loss, proximate analysis, and shear. Withdrawal times for feed or feed and water did not influence the tenderness or flavor of breast or thigh meat.

Effect of pattern of administration on the response to exogenous pituitary-derived chicken growth hormone by broiler-strain pullets.

The effect of pulsatile versus continuous intravenous administration of exogenous, pituitary-derived chicken growth hormone (cGH) on growth performance and endocrine/metabolite status of broiler-strain pullets was determined. In a first study, 8-week-old pullets, surgically prepared with intravenous catheters and maintained via a fluid swivel/spring tether/harness system, were administered cGH or vehicle (control) over a 10-min period every 90 min (i.e., 90-min pulse pattern) for 21 consecutive days. Feed intake, body weight gain, and carcass yield and composition were determined in conjunction with plasma concentrations of several hormones and metabolites. In a second study, 8-week-old pullets were intravenously administered cGH or vehicle continuously for 21 consecutive days under the same conditions as for Study I. Pulsatile cGH administration improved feed efficiency (P less than 0.02), increased longitudinal bone growth (P less than 0.02) and mass (P less than 0.01), and reduced abdominal fat pad size (P less than 0.05) and total carcass lipid (P less than 0.09) over the 21-day treatment period in comparison to vehicle infusion. Pulsatile cGH administration also resulted in hepatomegaly, a marked elevation in plasma IGF-I (P less than 0.003) and T3 (P less than 0.005) concentrations, and a reduction in plasma T4 levels (P less than 0.04). In contrast to the above responses to pulsatile cGH, continuous intravenous cGH administration significantly impaired feed efficiency (P less than 0.01) and had no significant effect on abdominal fat pad or liver size or on total carcass lipid, but did result in widening of the epiphyseal growth plate (P less than 0.06) and increased bone mass (P less than 0.01) in comparison to vehicle infused controls. These studies demonstrate that in the broiler chicken, for which endogenous plasma GH concentrations are pulsatile at early ages in conjunction with rapid growth, the pattern of exogenous GH administration is clearly a factor influencing the nature of response to the hormone.

Handling Perishable Foods.

Food service industry management has been interested in help to meet sanitary regulations, reduce food spoilage, lengthen keeping quality, and prevent foodborne illness. Materials were developed for 1-day workshops to provide practical suggestions for handling perishable and preserved foods. Products included were meats, poultry and eggs, milk and dairy products, delicatessen, fruits, vegetables and seafood. A 200-page reference book and 12 sets of slides or filmstrips were used to outline spoilage, food poisoning, personal hygiene, equipment sanitation, and proper food handling practices. A program has been conducted at 16 locations in Pennsylvania. Participants have been supervisors from stores, schools, hospitals, nursing homes, restaurants, vending companies, and fast food operations. Educational materials and programs will train food service personnel how to handle perishable foods.