Inactivation of Salmonella enteritidis on shell eggs by coating with phytochemicals.

Salmonella enteritidis (SE) is a major foodborne pathogen that causes human infections largely by consumption of contaminated eggs. The external surface of eggs becomes contaminated with SE from multiple sources, highlighting the need for effective egg surface disinfection methods. This study investigated the efficacy of three GRAS-status, phytochemicals, namely carvacrol (CR), eugenol (EG), and ß-resorcylic acid (BR) applied as pectin or gum arabic based coating for reducing SE on shell eggs. White-shelled eggs, spot inoculated with a 5-strain mixture of nalidixic acid (NA) resistant SE (8.0 log CFU/mL) were coated with pectin or gum arabic solution containing each phytochemical (0.0, 0.25, 0.5, or 0.75%), and stored at 4°C for 7 days. SE on eggs was enumerated on days 0, 1, 3, and 7 of storage. Approximately 4.0 log CFU/egg of SE was recovered from inoculated and pectin or gum arabic coated eggs on day 0. All coating treatments containing CR and EG, and BR at 0.75% reduced SE to undetectable levels on day 3 (P < 0.05). Results suggest that the aforementioned phytochemicals could effectively be used as a coating to reduce SE on shell eggs, but detailed studies on the sensory and quality attributes of coated eggs need to be conducted before recommending their use.

Use of plant-derived antimicrobials for improving the safety of poultry products.

Salmonella Enteritidis and Campylobacter jejuni are the 2 major foodborne pathogens transmitted through poultry products. Chickens are the reservoir hosts of these pathogens, with their intestinal colonization being the most significant factor causing contamination of meat and eggs. Effective preslaughter strategies for reducing the colonization of birds with these pathogens are critical to improve the microbiological safety of poultry products. An antimicrobial treatment that can be applied through feed represents the most practical and economically viable method for adoption on farms. Additionally, a natural and safe antimicrobial will be better accepted by producers without concerns for toxicity. This symposium talk discussed the potential use of plant-derived, GRAS (generally recognized as safe)-status molecules, caprylic acid, trans-cinnamaldehyde, eugenol, carvacrol, and thymol as feed supplements for reducing cecal populations of Salmonella Enteritidis and C. jejuni in chickens. Additionally, the effect of plant molecules on Salmonella virulence genes critical for cecal colonization in chickens was also discussed.

Caprylic acid reduces Salmonella Enteritidis populations in various segments of digestive tract and internal organs of 3- and 6-week-old broiler chickens, therapeutically.

We investigated the efficacy of feed supplemented with caprylic acid (CA), a natural, 8-carbon fatty acid for reducing Salmonella enterica serovar Enteritidis colonization in commercial broiler chickens. In separate 3- and 6-wk trials, 1-d-old straight-run broiler chicks (n = 70 birds/trial) were assigned to a control group (challenged with Salmonella Enteritidis, no CA) and 2 replicates of 0.7 and 1% CA (n = 14 birds/group). Water and feed were provided ad libitum. On d 1, birds were tested for any inherent Salmonella (n = 2 birds/group). For the 3-wk trial, on d 5, birds were challenged with 8 log(10) cfu of Salmonella Enteritidis of a 4-strain mixture by crop gavage, and after 5 d postchallenge, birds (n = 2 birds/group) were euthanized to ensure Salmonella Enteritidis colonization. Caprylic acid was supplemented the last 5 d before tissue collection (n = 10 birds/group). For the 6-wk trial, on d 25, birds were challenged and confirmed for Salmonella Enteritidis colonization. The birds (n = 10 birds/group) were euthanized for tissue samples after CA supplementation for the last 5 d. Caprylic acid at 0.7 or 1% decreased Salmonella Enteritidis populations in cecum, small intestine, cloaca, liver, and spleen in both 3- and 6-wk trials. Body weight of birds did not differ between the groups (P ≥ 0.05). Further, to elucidate a potential antibacterial mechanism of action of CA, we investigated if CA could reduce Salmonella Enteritidis invasion of an avian epithelial cell line and expression of invasion genes hilA and hilD. The cell invasion study revealed that CA reduced invasive abilities of all Salmonella Enteritidis strains by ~80% (P < 0.05). Gene expression studies indicated that CA downregulated (P < 0.001) Salmonella invasion genes hilA and hilD. These results suggest that supplementation of CA through feed could reduce Salmonella Enteritidis colonization in broiler chicken and potentially reduces the pathogen's ability to invade intestinal epithelial cells by downregulating key invasion genes, hilA and hilD.

Temperature sequence of eggs from oviposition through distribution: production--part 1.

During Egg Safety Action Plan hearings in Washington, DC, many questions were raised concerning the egg temperature (T) used in the risk assessment model. Therefore, a national study was initiated to determine the T of eggs from oviposition through distribution. In part 1; researchers gathered data on internal and surface egg T from commercial egg production facilities. An infrared thermometer was used to rapidly measure surface T, and internal T was determined by probing individual eggs. The main effects were geographic region (state) and season evaluated in a factorial design. Egg T data were recorded in the production facilities in standardized comparisons. Regression analysis (P < 0.0001) showed that the R(2) (0.952) between infrared egg surface T and internal T was very high, and validated further use of the infrared thermometer. Hen house egg surface and internal T were significantly influenced by state, season, and the state x season interaction. Mean hen house egg surface T was 27.3 and 23.8 degrees C for summer and winter, respectively, with 29.2 and 26.2 degrees C for egg internal T (P < 0.0001). Hen house eggs from California had the lowest surface and internal T in winter among all the states (P < 0.0001), whereas the highest egg surface T were recorded during summer in North Carolina, Georgia, and Texas, and the highest internal T were recorded from Texas and Georgia. Cooling of warm eggs following oviposition was significantly influenced by season, state, and their interaction. Egg internal T when 3/4 cool was higher in summer vs. winter and higher in North Carolina and Pennsylvania compared with Iowa. The time required to 3/4 cool eggs was greater in winter than summer and greater in Iowa than in other states. These findings showed seasonal and state impacts on ambient T in the hen house that ultimately influenced egg surface and internal T. More important, they showed opportunities to influence cooling rate to improve internal and microbial egg quality.

Temperature sequence of eggs from oviposition through distribution: processing--part 2.

The Egg Safety Action Plan released in 1999 raised questions concerning egg temperature used in the risk assessment model. Therefore, a national study was initiated to determine the internal and external temperature sequence of eggs from oviposition through distribution. Researchers gathered data from commercial egg production, shell egg processing, and distribution facilities. The experimental design was a mixed model with 2 random effects for season and geographic region and a fixed effect for operation type (inline or offline). For this report, internal and external egg temperature data were recorded at specific points during shell egg processing in the winter and summer months. In addition, internal egg temperatures were recorded in pre- and postshell egg processing cooler areas. There was a significant season x geographic region interaction (P < 0.05) for both surface and internal temperatures. Egg temperatures were lower in the winter vs. summer, but eggs gained in temperature from the accumulator to the postshell egg processing cooler. During shell egg processing, summer egg surface and internal temperatures were greater (P < 0.05) than during the winter. When examining the effect of shell egg processing time and conditions, it was found that 2.4 and 3.8 degrees C were added to egg surface temperatures, and 3.3 and 6.0 degrees C were added to internal temperatures in the summer and winter, respectively. Internal egg temperatures were higher (P < 0.05) in the preshell egg processing cooler area during the summer vs. winter, and internal egg temperatures were higher (P < 0.05) in the summer when eggs were (3/4) cool (temperature change required to meet USDA-Agricultural Marketing Service storage regulation of 7.2 degrees C) in the postshell egg processing area. However, the cooling rate was not different (P > 0.05) for eggs in the postshell egg processing cooler area in the summer vs. winter. Therefore, these data suggest that season of year and geographic location can affect the temperature of eggs during shell egg processing and should be a component in future assessments of egg safety.

Temperature sequence of eggs from oviposition through distribution: transportation--part 3.

The Egg Safety Action Plan released in 1999 raised many questions concerning egg temperature used in the risk assessment model. Therefore, a national study by researchers in California, Connecticut, Georgia, Iowa, Illinois, North Carolina, Pennsylvania, and Texas was initiated to determine the internal and external temperature sequence of eggs from oviposition through distribution. Researchers gathered data from commercial egg production, processing, and distribution facilities. The experimental design was a mixed model with random effects for season and a fixed effect for duration of the transport period (long or short haul). It was determined that processors used refrigerated transport trucks (REFER) as short-term storage (STS) in both the winter and summer. Therefore, this summary of data obtained from REFER also examines the impact of their use as STS. Egg temperature data were recorded for specific loads of eggs during transport to point of resale or distribution to retailers. To standardize data comparisons between loads, they were segregated between long and short hauls. The summer egg temperatures were higher in the STS and during delivery. Egg temperature was not significantly reduced during the STS phase. Egg temperature decreases were less (P < 0.0001) during short delivery hauls 0.6 degrees C than during long hauls 7.8 degrees C. There was a significant season x delivery interaction (P < 0.05) for the change in the temperature differences between the egg and ambient temperature indicated as the cooling potential. This indicated that the ambient temperature during long winter deliveries had the potential to increase egg temperature. The REFER used as STS did not appreciably reduce internal egg temperature. These data suggest that the season of year affects the temperature of eggs during transport. Eggs are appreciably cooled on the truck, during the delivery phase, which was contrary to the original supposition that egg temperatures would remain static during refrigerated transport. These data indicate that refrigerated transport should be a component in future assessments of egg safety.

Egg marketing in national supermarkets: egg quality--part 1.

Two surveys were conducted to determine the quality of eggs offered to consumers in large supermarkets in various regions of the US. The first survey was conducted in California (CA) in 1994 and included 38 samples of large (L) and extra large (XL) white eggs in 15 markets. Individual eggs were weighed, candled, and broken out for Haugh unit (HU) determination. Regional differences in age of eggs, the number of eggs below 55 HU, and the percentage of cracked eggs were observed. The second survey was conducted in California (CA), Illinois (IL), Pennsylvania (PA), Texas (TX), North Carolina (NC), and New England (NE). This study included brown and white eggs and samples from 115 stores in 38 cities. Significant age, egg weight, HU, and cracked egg differences were observed between states. Brown and white eggs were different relative to age and HU, but egg weights and cracked eggs were statistically the same. The two surveys, 1994 and 1996, within CA demonstrated very similar measurements when L-white eggs were compared.

Egg marketing in national supermarkets: specialty eggs--part 2.

Large eggs promoted as having one or more features beyond conventional white or brown shell eggs (specialty eggs) were evaluated for quality and price in a national retail study. Subtypes of specialty eggs included: nutritionally altered eggs, organic eggs, fertile eggs, eggs from welfare-managed hens, or hens fed all-vegetable diets. Extension Poultry Specialists in California (CA), Connecticut, Illinois, North Carolina, Pennsylvania and Texas conducted a survey of egg quality and price and compared 246 dozen specialty eggs with 390 dozen conventional white shell eggs during the summer of 1996. Age of the eggs based on carton dating indicated specialty eggs were older (16.5 d) than white eggs (11.7 d). Average egg weights for specialty compared to white were 60.2 and 59.6 g, respectively. Interior egg quality evaluations including albumen height, Haugh units (HU), and percentage HU <55, indicated white eggs were superior (5.0 mm, 67.5, and 10.6%, respectively) compared to specialty eggs (4.7 mm, 63.8, and 16.3%). Although the percentage of cracked eggs was similar between specialty and white eggs (5.4 and 5.7%), the percentage of leakers was threefold higher for the specialty eggs (1.0 vs. 0.3%). Egg price was substantially higher for the specialty eggs, averaging $2.18/dozen with a range from 0.88 to $4.38, compared to white eggs, averaging $1.23/dozen and ranging from 0.39 to $2.35.

Egg marketing in national supermarkets: products, packaging, and prices--part 3.

As part of a national retail egg quality study, the variety of shell eggs and egg products offered for sale, type of packaging, and price relationships were compared in five major metropolitan regions. A total of 81 stores in 28 cities were sampled in California (CA), Illinois (IL), North Carolina (NC), Texas (TX), and New England (NE). Data were recorded for the variety of brands, sizes, white or brown shell eggs, specialty eggs, liquid or frozen eggs, carton sizes, package labeling and coding, and price relationships of shell eggs, liquid, and frozen egg products displayed for sale. The total variety of shell eggs displayed per store was the greatest for CA and NE stores. Stores in CA and TX offered more (P < 0.05) variety of white shell eggs than did stores in the other states, whereas stores in NE displayed the greatest variety (P < 0.05) of brown shell eggs. The average number of liquid and frozen egg products was highest (P < 0.05) for NC stores. Packaging type, USDA labeling, and carton coding differed somewhat among states. The price per one dozen cartons of all white shell egg sizes was highest (P < 0.05) in CA stores, and the average liquid plus frozen egg product prices were higher in CA and NE stores compared to the other states. However, the ratio of liquid and frozen product prices to all large shell egg prices was among the lowest for CA and NC stores. These data indicate that product selection, packaging, and consumer prices for shell eggs and egg products varied considerably across five separate regions of the country.

Effect of albuterol on oxygen uptake and Na+-K+ ATPase activity of jejunal epithelia and liver in chickens.

Changes in metabolic characteristics of the liver and jejunal epithelia as a result of feeding the beta-agonist albuterol to chickens for 3 and 6 weeks were studied. Feeding albuterol resulted in a change in weights of the liver and small intestines. Chickens fed albuterol for 6 weeks had greater levels of plasma nonesterified fatty acids than those fed the control diet. Oxygen uptake by liver and jejunal epithelial tissues were 25 and 26% greater for chickens fed the diet with albuterol than for those fed the control diet, respectively. No changes in Na+-K+ ATPase activity of both liver and jejunal epithelia were detected as a result of feeding albuterol. These findings indicate that certain beta-agonists may elevate thermogenesis in chickens as a result of increasing metabolic rates of splanchnic tissues. However, the changes resulting in altering oxygen uptake in liver and jejunal epithelia due to feeding albuterol were not associated with Na+-K+ ATPase activity.

Heart rate, blood pressure, cardiac output, and total peripheral resistance of single comb White Leghorn hens during an acute exposure to 35 C ambient temperature.

Two experiments were undertaken to determine selected cardiovascular responses of laying hens to a thermal challenge at 35 C ambient temperature. In the first, six Single Comb White Leghorn (SCWL) hens were exposed to 35 C and changes in systolic and diastolic blood pressure, heart rate, respiratory rate, and rectal temperatures were determined. In the second, seven SCWL hens were exposed to 35 C and changes in cardiac output, total peripheral resistance, blood pressure, heart rate, respiratory rate, and rectal temperature were monitored. In the first experiment heart rate and blood pressure decreased. In the second experiment there was a 58% increase in cardiac output and a 50% decrease in total peripheral resistance accompanied by a 9% decrease in mean blood pressure. Changes in cardiovascular tone preceded respiratory adjustments during acute heat challenges. This may represent one of the most efficient means of heat dissipation for the bird.

The effect of pinealectomy on metabolism and somatic growth of immature cockerels.

Fifty-four 1-day-old Single Comb White Leghorn cockerels were randomly assigned to 18 brooder cages across three surgical treatments, pinealectomy (PX), sham-operated (PN), and non-operated controls (C). Pinealectomy and sham-operations were performed at 9 days of age. The birds were maintained for 28 days, during which time body weight, feed consumption, and oxygen consumption were measured. All parameters were similar for all treatments during the week before surgery. During the first week after surgery, the PX birds had a lower (P less than .05) oxygen consumption and lowered (P less than .05) body weight gains compared to PN and C birds. Shortly after recovering from surgery, the PX birds became very docile and engorged their crops. This unusual behavior was not seen in the PN or C birds. By the second week after surgery, the oxygen consumption was similar for all treatments. At 21 days of age the PX birds had a significantly (P less than .05) lower body weight compared to the PN and C birds.

Caloric value of cardiac response to hot environments.

Single Comb White Leghorn hens were placed in a controlled temperature chamber, initially at 26 C and subsequently raised to 35 C. Recordings of the surface and rectal temperatures, respiratory rate, heart rate, and oxygen consumption were made at the 26 C basal temperature and compared with those made at the 35 C ambient temperature. Sequential doses of saline and atropine were injected following the thermoregulatory response of birds to 35 C. The thermal challenge resulted in an average increase of 53 breaths per minute in the respiratory rate during the pre-injection period at 35 C and rose steadily to the end of the thermal challenge. The saline elicited no effects on any parameter measured; however, the atropine resulted in a mean increase of 62 beats per minute in the heart rate. There was no difference in the pre-atropine heart rate at 35 C and the basal heart rate at 26 C. Following the atropine induced increase in heart rate there was a 13% increase in energy expenditure. Thermal-bradycardia in hot environments may represent a first line of defense against hyperthermia by reducing the added heat load.

Influence of gonadotropic releasing hormone, luteinizing hormone and pineal extracts on testes of immature cockerels.

Two, seven, and ten-day-old S.C.W.L. cockerels were injected with pineal extract (PE), gonadotropic releasing hormone (GnRH) and luteinizing hormone (LH), alone or in combination, to determine the effect of PE on the action of exogenous GnRH and LH on the testis in immature cockerels. Radioactive phosphorus (P-32) uptake by the testis was used as an assay for gonadotropic activity. GnRH had no effects on cockerels aged two days. However, LH caused increased P-32 uptake compared to the saline control at this age. In seven- and ten-day-old cockerels, PE in combination with GnRH resulted in lower P-32 c.p.m./g. of testis compared to the non-PE treated birds at the same doses of GnRH. On the other hand, PE did not cause any decrease in testis response to LH. These results indicate that PE is acting to inhibit release of gonadotropins by GnRH.