SEARCH · PubMed Health

Results for “Broilers”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 433 records · Page 24Linked to original sources

PubMed1997

Effect of dietary aminoguanidine on tissue pentosidine and reproductive performance in broiler breeder hens.

Factors influencing the age-related decline in production parameters of broiler breeder hens are poorly understood. Elevated blood glucose concentrations measured in broiler breeder hens may contribute to this decline. The nonenzymatic attachment of glucose to proteins generates glycoxidation crosslinks in tissue proteins, which can ultimately impair their function. One such glycoxidation crosslink, pentosidine, has been used as a biomarker for aging studies because of its accumulation on the structural protein collagen. The objectives of these studies were to determine whether pentosidine accumulates with age in hens and whether the crosslinking inhibitor, aminoguanidine (AG), could retard this accumulation. An additional objective was to determine whether AG had any effect on production performance. In the first study, broiler breeder hens (n = 318) were randomly assigned to two groups: control and supplemented (400 ppm AG). Pentosidine was measured in the skin of the birds at 20 and 67 wk of age. Egg production was measured daily. In a second study, broiler breeder hens (n = 60) were reared as previously described. Pentosidine was measured in the skin of the birds at 20 and 68 wk of age. Results showed that pentosidine was present in the skin of the hens, and that concentrations increased with age (P < 0.001). Although pentosidine was reduced (P < 0.001) in AG-supplemented birds, production performance was not affected. In conclusion, AG retarded the rate of accumulation of pentosidine during lay in broiler breeder hens, but the reduction in pentosidine did not significantly affect production performance.

Aging↗

PubMed1997

Chronic unilateral occlusion of an extrapulmonary primary bronchus induces pulmonary hypertension syndrome (ascites) in male and female broilers.

Previously, it was demonstrated that acute (4 min) and chronic (12 d) occlusion of an extrapulmonary primary bronchus triggers pulmonary hypertension but not pulmonary hypertension syndrome (PHS, ascites) in broilers. The present study was conducted to determine whether a more prolonged period of bronchus occlusion causes PHS similar to that induced by clamping one pulmonary artery. Male and female broiler chicks, 14 to 18 d old, were anesthetized, the thoracic inlet was opened, and a silver clip was positioned to fully obstruct the left extrapulmonary primary bronchus (BRONCHUS CLAMP group) or the left pulmonary artery (PA-CLAMP group). Sham-operated chicks were anesthetized and the thoracic inlet was opened; however, neither the pulmonary artery nor the bronchus was clamped (SHAM group). An electrocardiogram (ECG) was obtained whenever clinical ascites became apparent in individual broilers, or prior to the final necropsy for broilers surviving to the end (Day 36) of the experiment. The right:total ventricular weight ratio (RV:TV) was evaluated as an index of pulmonary arterial pressure. Early post-surgical mortality (up to 21 d of age) was higher in the PA-CLAMP group (27% for males and females combined) than in the BRONCHUS CLAMP (10%) and SHAM (2%) groups. Cumulative ascites mortality (Days 22 to 36) also was higher in the PA-CLAMP group (86% for males, 77% for females) than in the BRONCHUS CLAMP (69% for males, 41% for females) and SHAM (23% for males, 0% for females) groups. Ascitic birds in all treatment groups had higher RV:TV ratios and more negative ECG Lead II S-wave amplitudes than nonascitic birds, reflecting the right ventricular hypertrophy and generalized ventricular dilation typically associated with PHS. These results demonstrate that unilateral bronchus occlusion is an effective experimental model for triggering ascites at a lower incidence than that obtained by occluding one pulmonary artery. Following the onset of pulmonary hypertension, the pathophysiological progression leading to ascites appears to be similar for broilers with either unilateral bronchus or pulmonary artery occlusion.

Animals↗

PubMed1997

Characteristics of the pectoralis superficialis and semimembranosus of broiler strain chickens, bantam chickens, and the reciprocal crosses.

At hatch, chicks from bantam sire x broiler dam (BaBr) matings were as heavy as those from broiler sire x broiler dam (BrBr) matings. Both were heavier than pure bantam chicks (BaBa) or chicks from broiler strain sires and bantam dams (BrBa), but weights of the latter two genotypes were identical. The Pectoralis superficialis and Semimembranosus of pure bantam chicks weighed less than those of pure broiler chicks throughout the studies. Muscle weights in the BaBr chicks were markedly heavier than those of genetically similar BrBa chicks at hatch. Genetic influences were quickly expressed and weights of muscles in these two groups had converged by 14 d of age. Myofiber cross-sectional areas at 1 d of age were not clearly associated with genotype or maternal environment, but clear patterns had begun to develop by 4 d of age. Myofiber area of both muscles was greater in BrBr than BaBa chicks by this age and after. Myofiber areas in the reciprocal crosses converged toward each other and away from the pure line chicks. By 11 d, the area of Pectoralis myofibers of BrBr chicks was greatest, those of the reciprocal crosses was intermediate and equal to each other, and that of BaBa chicks was least. A similar trend was apparent in Semimembranosus fibers by 11 d but the differences did not become significant until 21 d of age. Significant differences in myofiber number of the Semimembranosus were present (BrBr > BaBr > BrBa > BaBa). Thus, differences in muscle mass were the result of differences in both fiber number and fiber size.

Analysis of Variance↗

PubMed1998

Evaluation of the duration of sperm fertilizing ability in five lines of commercial broiler breeder and Delaware cross males.

The ability to characterize the reproductive potential of male fowl can be affected by a number of factors, including age, type, insemination scheme, and number of sperm inseminated. Fertility is a complex interaction of traits involving two individuals of differing genetic composition: In modern broiler breeders, selected predominantly for growth and carcass characteristics, fertility problems may be exacerbated. In order to evaluate the male components of fertility, an experiment investigating the effects of male line on both average fertility and the duration of fertility was completed. Male chicks from five commercial broiler breeder male lines or sired by subfertile Delaware cross roosters were reared to adulthood. Between 30 and 60 wk of age, semen was collected from five males per line, extended and used to inseminate each of 10 to 12 hens from four broiler breeder female lines or Single Comb White Leghorn hens with 80 x 10(6) live sperm. Following a single insemination eggs were collected for 21 d and fertility determined by visual inspection following 4 d incubation. The percentages of live sperm and overall fertility data for the replicate trials were analyzed, following transformation, with a linear model and daily fertility data were analyzed by iterative least squares regression. Whereas there were large differences in fertility among individual males (durations from 3.4 to 14.5 d) within a line, there were no significant male line or replicate effects on overall fertility or the duration of fertility. However, there was a significant (P < 0.05) line-dependent reduction in the percentage of live sperm in broiler breeder males, with the subfertile Delaware cross males being intermediate. There were no significant female line or replicate effects on the duration of fertility; however, there were significant female line effects on overall fertility at both 7 and 21 d. These data suggest that although individual males varied widely, there were no male line effects on the duration of fertility in the lines of broiler breeders evaluated when analyzed by iterative least squares. Furthermore, these data suggest that although females may have significant affects on overall fertility, the duration of fertility appears to be a predominantly male characteristic. Therefore, iterative least squares regression may be a useful tool for identifying males with superior sperm fertilizing ability.

Animals↗

PubMed1998

Mechanical harvesting of broilers.

At the end of the growout phase of broiler production essentially all broilers are caught and loaded into coops or cages entirely by hand. The catching of broilers remains one of the few aspects of broiler production not yet automated. Vacuum systems, permanent conveyors recessed in the floors of growout facilities, collecting mats, scoops, and self-propelled, combine-type devices have been tried with little success over the past 30 yr. Renewed efforts at developing mechanical broiler harvesters have been encouraging in recent years. Several equipment companies in North America and Europe have developed prototype mechanical harvesters that appear to have promise. The benefits of mechanical harvesting as compared to hand catching include lower costs and improved working conditions. In addition, studies conducted thus far indicate that mechanical harvesting will improve bird welfare both from a stress and injury standpoint.

Agriculture↗

PubMed1998

A broiler chick bioassay for measuring the feeding value of wheat and barley in complete diets.

Energy is an important component of poultry feed and is derived principally from cereal grains. Unfortunately, all of the chemical energy is not available to the bird, and biological assays must be used to determine the digestible energy value of a cereal grain. The bioassay described uses four pens of six male broiler chicks, complete diets containing 80% of a test cereal grain (with or without an appropriate commercial enzyme), and ad libitum feed intake. Apparent metabolizable energy values (kilocalories per kilogram of cereal grain, DM basis) values are calculated from gross energy and acid insoluble ash measurements of diet and excreta collected for 24 h at 16 d of age. To monitor variation between broiler chick assays, due to bird, environment, etc., common control samples of Hard Red Spring (HRS) and Canadian Prairie Spring (CPS) wheat were tested in each of 15 separate assays over 2 yr. Similarly, for barley, control samples of hulled and hulless barley were repeatedly tested in five assays. Broiler performance in this study was lower than expected for commercial broilers, in part due to a high dietary cereal grain component and the fine mash texture. However, AME values as determined were comparable to those reported in the literature for wheat and barley. The CV for AME measured among pens, representing the intra-assay CV, was between 1.2 and 3.4% and was lower with enzyme supplementation. The interassay CV was only slightly higher than the intra-assay CV. This assay provides precise estimations of ME in cereal grains fed to young broilers that can be used for diet formulation or for verification of laboratory measures of feeding value of cereal grains.

Animal Feed↗

PubMed1998

Comparison of sample source (excreta or ileal digesta) and age of broiler chick on measurement of apparent digestible energy of wheat and barley.

The broiler chick bioassay measures AME of wheat- or barley-based diets, with or without an enzyme, from excreta (24-h collections at 8 or 16 d) and ileal digesta (17 d). The objective was to discuss the merits and accuracy of sample source (excreta vs ileal digesta) and bird age for determining the feeding value of wheat and barley. The bioassay utilized 80% of a test cereal grain, 20% basal diet containing 1.1% acid insoluble ash marker, and fed with or without an enzyme to four pens of six male broilers from 4 to 17 d. A total of 138 wheat and 97 barley samples (with and without an enzyme) were tested in 15 and five bioassays, respectively. Within each wheat or barley bioassay two control wheat and barley samples were measured. The among-pens and between-assays CV for AME were calculated for these control samples, and correlation coefficients between the measures were calculated for the controls and for all of the 138 wheat and 97 barley samples included in the assays. For wheat samples, values for AME were lowest for excreta samples collected at 8 d, and similar for excreta and ileal digesta samples collected at 16 and 17 d, respectively. For barley samples, the three values were significantly different. The among-pens and between-assay CV were low for AME among both wheat and barley samples. Correlation coefficients between several measures of AME at 8 and 16 d were significant for the control samples with enzyme supplementation. When all samples were included in the analysis, correlation coefficients between AME measures were moderate to high. On the basis of accuracy, precision, and cost, these data favor measuring AME on excreta samples at 16 d of age. Comparisons of number of pens of broilers used to determine AME would suggest that much of the variability predicted with four pens of six broilers each could be achieved with three, and possibly two pens of six broilers each, thereby greatly increasing the capacity of the assay to screen large numbers of samples.

Aging↗

PubMed1998

Antioxidant defenses in lung lining fluid of broilers: impact of poor ventilation conditions.

Lung lining fluid antioxidants represent a potentially important protective barrier of lung epithelial cells to damaging effects of air pollutants, yet no information is apparently available concerning lung lining fluid antioxidants in broilers. Therefore, goals of this study were to establish uric acid, ascorbic acid, reduced (GSH) and oxidized (GSSG) glutathione, and protein concentrations in lung lining fluid obtained from male broiler chickens maintained for 6 to 7 wk within environmentally controlled rooms (Control) or chronically exposed to high levels of dust and ammonia within a broiler rearing house (House). The entire respiratory tract was carefully removed following an overdose of anesthetic and lavage fluid was collected after flushing the lungs with heparin-saline (10 mL per lung). There was no difference in GSH, but GSSG, uric acid, and protein concentrations were higher in House birds than in Controls. An increase in the GSSG to total glutathione (GSx) ratio, an indicator of oxidative stress, was also observed in birds maintained in the House environment. Ascorbic acid was not detected in House-reared birds and detected in only 4 of 12 Controls. Regression analysis revealed positive correlations between lung lining fluid protein and uric acid (r = 0.71; P < 0.01), protein and GSSG (r = 0.73; P < 0.01), and uric acid and GSSG concentrations (r = 0.69, P < 0.01). Additionally, GSSG was positively correlated (r = 0.66; P < 0.01) with the right ventricular weight ratio, an index commonly used in identifying the development of pulmonary hypertension syndrome in broilers. These data, the first to document lung lining fluid antioxidants in avian species, indicate an oxidative stress can be detected in fluid of broilers exposed to high levels of dust and ammonia in a simulated poultry house environment.

Animals↗

PubMed1998

The effect of thermal preslaughter stress on the susceptibility of broiler chickens differing with respect to growth rate, age at slaughter, blood parameters, and ascites mortality, to hemorrhages in muscles.

In this study we investigated the occurrence of hemorrhages in four groups of electrically stunned broilers, differing with respect to growth rate, age at slaughter, hemodynamic parameters, and ascites mortality. In addition, the effect of three thermal preslaughter conditions on hemorrhage occurrence in thigh and breast muscles was studied. Broilers were either reared at a thermoneutral or low temperature regimen, and were either restricted in their feed consumption or consumed feed ad libitum. Prior to slaughter the broilers were exposed for 2 +/- 0.5 h to either cold (4 +/- 2 C, RH 100%), moderate (19 +/- 2 C, RH: 70 to 80%), or warm (30 +/- 2 C, RH: 60 to 70%) conditions. There was no effect of rearing group, nor was there an interaction between rearing group and preslaughter condition on hemorrhage scores in the thighs or breasts. Preslaughter conditions only affected hemorrhage scores in the left thigh. Scores were highest in broilers exposed to moderate preslaughter conditions. These data indicate that the cause of hemorrhages in muscles is multifactorial. Hemorrhage severity was not diminished in broilers retarded in growth. Pathological hemodynamic adaptations to low rearing temperatures, leading to ascites, did not increase hemorrhage severity, neither upon exposure to moderate nor to cold or warm preslaughter conditions.

Aging↗

PubMed1998

Growth performance, intestinal microbial populations, and serum cholesterol of broilers fed diets containing Lactobacillus cultures.

A study was conducted to determine the effects of adherent Lactobacillus culture on growth performance, intestinal microbial population, and serum cholesterol level of broilers. Four dietary treatments, consisting of the basal diet (control), basal diet + 0.05, 0.10, or 0.15% Lactobacillus culture (LC), were fed to 2,000 Arbor Acres broiler chicks from 1 to 42 d of age (DOA). The chicks were randomly assigned to 40 cages (50 chicks per cage, 10 cages per diet). The experimental period was 42 d. Body weights and feed to gain ratio were measured at 21 and 42 DOA. The intestinal microbial populations and serum cholesterol levels were determined at 10, 20, 30, and 40 DOA. The results showed that body weights and feed to gain ratios were improved significantly (P < 0.05) when compared to control broilers for broilers fed diets containing 0.05 or 0.10% LC, but not 0.15% LC, at 21 and 42 DOA. Coliform counts in the cecum of birds receiving 0.05% LC at 10, 20, and 30 DOA, and 0.10% at 10 and 20 DOA were significantly lower (P < 0.05) than those of the control birds. The total aerobes, total anaerobes, lactobacilli, and streptococci in the small intestines and ceca of the control birds were not significantly different from those of the treated groups. Serum cholesterol levels were significantly lower (P < 0.05) in broilers fed the three diets containing LC at 30 DOA, and in the birds fed 0.05 or 0.10% LC at 20 DOA.

Animal Nutritional Physiological Phenomena↗

PubMed1999

Presence of Salmonella in the crop and ceca of broiler chickens before and after preslaughter feed withdrawal.

Recent studies have suggested that crop contents may serve as an important source of Salmonella carcass contamination within processing plants. During the present study, we evaluated the effect of preslaughter feed withdrawal on the presence of Salmonella in the crops of broilers from nine commercial broiler flocks reared in individual growout houses. Crops were collected aseptically from 40 randomly selected broilers in each flock before feed removal and at the end of the feed withdrawal period, immediately before capture and transport to the processing plant. Similarly, the ceca were collected before and after feed withdrawal in six of the nine broiler flocks. The presence of Salmonella in the crops and ceca was determined by enrichment culture in tetrathionate broth followed by culture on brilliant green agar. The incidence of Salmonella in crop contents increased significantly (P < 0.05) in five of the nine flocks during feed withdrawal. The total number of Salmonella contaminated crops from all nine flocks increased significantly (P < 0.005) from 7/360 (1.9%) before feed removal to 36/359 (10.0%) at the end of feed withdrawal. The increased incidence of Salmonella in the crop contents was associated with an increased tendency of the broilers to consume contaminated rearing house litter during feed withdrawal. The incidence of Salmonella in the ceca increased nonsignificantly from 14/240 (5.8%) before feed removal to 19/240 (7.9%) at the end of feed withdrawal. The results indicate that the incidence of Salmonella crop contamination may increase as much as fivefold during preslaughter feed withdrawal and represent a critical preharvest control point in reducing Salmonella entry into the processing plant.

Animals↗

PubMed1999

Electrocardiographic evaluation of broilers following unilateral occlusion of an extrapulmonary primary bronchus.

This study was conducted to provide a comprehensive evaluation of both the amplitudes and durations of the Lead II electrocardiogram (ECG) in nonascitic and ascitic broilers. At 14 d of age, male and female broiler chicks were sham-operated (SHAM, n = 27), or pulmonary hypertension was initiated by occluding one extrapulmonary primary bronchus (BRONCHUS CLAMP, n = 57). Lead II ECG and BW were recorded on Days 28 (ECG1) and 42 (ECG2), necropsies were conducted on all birds dying after Day 28, and final necropsies were conducted on Day 49. Data collected at necropsy included the presence (ASCITIC) or absence (NONASCITIC) of ascites, sex, and ventricular weights for calculating the right:total ventricular weight ratio (RV:TV), which serves as a reliable index of pulmonary hypertension. In each bird, three consecutive ECG1 and ECG2 wave cycles were quantified for both amplitude and duration of the following wave segments: Rb-R, R-S, S-R', R'-R'b, and S-T. The S wave amplitude was calculated by subtracting R-S from Rb-R and heart rate (HR) was measured from the peak of one T wave to the peak of the next. In the majority of comparisons, ASCITIC and BRONCHUS CLAMP broilers had larger S, R'-R'b, and S-T amplitudes, longer R-S, R'-R'b, and S-T durations, and a slower HR than NONASCITIC and SHAM broilers, regardless of sex. The differences in ECG wave forms and durations between ASCITIC and NONASCITIC broilers were greater on Day 42 (ECG2) than on Day 28 (ECG1), but when both ECG were used to develop a regression equation to estimate RV:TV, the R2 was 0.79. The most important Lead II ECG parameters associated with the development of ascites were an increasingly negative S wave amplitude and greater amplitudes and durations for R'-R'b and S-T as well as a decrease in the HR.

Airway Obstruction↗

PubMed1999

Broiler breeder survivors of chronic unilateral pulmonary artery occlusion produce progeny resistant to pulmonary hypertension syndrome (ascites) induced by cool temperatures.

Chronic occlusion of one pulmonary artery triggers a high incidence of pulmonary hypertension syndrome (PHS, ascites) in broilers. In the present study, the left pulmonary artery was chronically occluded in 295 male and 255 female chicks pedigreed from 18 sire families, leading to PHS in 74% of the males and 45% of the females. Survivors were reared to breeding age and served as parents for the resulting PHS-resistant chicks (Resistant), whereas control chicks were produced from the base population for this line (Base). In two experiments, male and female Resistant and Base chicks were reared separately by sex but mixed by group within environmental chambers, where they were exposed to cool (14 C) temperatures. In both experiments, the incidence of PHS was at least 50% lower in the Resistant males and females than in the Base males and females, respectively. When compared within a sex, the Base and Resistant broilers surviving to the end of both experiments did not differ in final body weight or body weight gain, nor did their right:total ventricular weight (RV:TV) ratios differ. These results demonstrate that broiler breeders capable of thriving after having their entire cardiac output forced to flow through one lung, subsequently produced male and female progeny with substantially improved resistance to the onset of PHS induced by fast growth and exposure to cool environmental temperatures. Fast growth and cool temperatures are primary triggers for PHS under most conditions of commercial broiler growout. In both experiments, final necropsies revealed higher RV:TV ratios in ascitic than in nonascitic broilers, whereas normalizing the left ventricle plus septum weight for differences in body weight generated similar values for ascitic and nonascitic males or females, respectively. These results support a primary role for pulmonary hypertension but not cardiomyopathy in the pathogenesis of ascites triggered by cool temperatures in both the Base and Resistant populations.

Animal Husbandry↗

PubMed1999

A geneticist's perspective from within a broiler primary breeder company.

Recent trends occurring in broiler primary breeding companies are described. The structure and operation of broiler primary breeder companies are described from pedigree elite populations, through great-grandparent and grandparent generations, down to the parent stock. The relatively low value of fertility and hatchability, compared with yield and feed efficiency as selection traits, is assessed. The impact of the last 10 yr of genetic improvement in broiler and breeder traits are quantified and discussed, and predictions for future performance are made. It is concluded that artificial insemination will not be used in broiler primary breeder grandparent flocks or broiler breeder flocks until there is a 20% decline in fertility.

Animal Husbandry↗

PubMed1999

The effect of feed withdrawal on broiler blood glucose and nonesterified fatty acid levels, postmortem liver pH values, and carcass yield.

Feed withdrawal should start 5 h before broilers are captured and transported to the processing plant. This practice results in a total feed withdrawal period of about 8 h before slaughter. To check observance of this period at the plant reliably, blood samples were collected at slaughter from broilers. These samples were analyzed for glucose and nonesterified fatty acid (NEFA). Glucose levels decreased, whereas the amount of NEFA increased as a consequence of deprivation. It was found that the decrease in glucose was smaller than could be expected from data in the literature, whereas the level tended to rise again after longer deprivation periods. The increase of the NEFA was lower in males than in females, and the glucose: NEFA ratio also showed a difference between the sexes. Therefore, it was concluded that these blood metabolites were not suitable for use as an indicator of the duration of feed withdrawal. The estimation of liver pH seemed to be a more reliable indicator of the length of feed withdrawal. Longer periods of feed withdrawal resulted in higher ultimate liver pH values, which were 6.10 to 6.20 in full-fed broilers, increasing to 6.60 in livers from broilers deprived during longer withdrawal periods. Further research, however, is needed because broilers in the present study were exposed to minimal amounts of stress. Other carcass characteristics such as slaughter, evisceration, and oven-ready yields matched results previously described in the literature.

Abattoirs↗

PubMed1999

The effects of captive bolt and electrical stunning, and restraining methods on broiler meat quality.

The effects of captive bolt stunning using air pressure, compared to electrical water bath stunning, on broiler carcass and meat quality were evaluated. The birds were shackled or placed in a cone. Two trials were conducted using a total of 160 female broilers. The four stunning-restraining treatments were whole-body electrical stunning (10 s, 110 mA, 300 Hz) in a water bath or air pressure stunning (0.5 s, 2 atm) while broilers were shackled by their feet or placed in a cone. Air pressure stunning caused a higher (P < 0.01) degree of convulsions and a lower (P < 0.01) degree of blood loss than electrical stunning, and reduced the prevalence of broken clavicles (P < 0.05) and coracoids (P < 0.01). Blood loss of shackled broilers was slightly higher (P < 0.05) than those restrained in a cone. Air pressure stunning resulted in significantly (P < 0.01) lower pH values and hemorrhaging in filets and thigh muscles than electrical stunning. The incidence of thigh muscle hemorrhaging was significantly (P < 0.01) reduced when broilers were restrained in a cone compared to being shackled. The stunning and restraining treatments did not result in differences in cooking losses. The filets from shackled birds were judged more tender than the filets from cone-restrained birds. With respect to the effect of stunning method, the filets of air pressure stunned birds was judged more tender than the meat from electrically stunned birds. Captive bolt stunning using air pressure has benefits over electrical stunning; however, a suitable stunning and restraining device remains to be developed.

Abattoirs↗

PubMed2000

Physical, chemical, and microbiological changes in the crop of broiler chickens subjected to incremental feed withdrawal.

Trials were conducted to determine the effect of feed withdrawal on the weight, pH, native bacterial flora, and Salmonella typhimurium persistence in crops of broilers. Six-week-old broilers were provided medicated or unmedicated feed and were subjected to feed withdrawal for 0 to 24 h in transportation crates or on litter. After feed withdrawal, broilers were stunned, bled, scalded, and picked. Crops were aseptically removed and weighed. Crops were then blended in 20 mL distilled water, and pH values of the suspensions were measured. Aerobic bacteria, Enterobacteriaceae, S. typhimurium, and lactic acid bacteria in the suspension were enumerated on appropriate bacteriological media. Feed withdrawal produced significant decreases in the crop weights. Crop pH increased by 1.0 unit within 6 h of feed withdrawal. Enterobacteriaceae and S. typhimurium populations generally decreased during the first 12 h of feed withdrawal and remained unchanged or increased during the final 12 h of the 24-h feed withdrawal period. The number of lactic acid bacteria recovered from the crop usually decreased as the duration of feed withdrawal increased. Changes in crop weights, pH, native microflora, or the recovery of S. typhimurium from the crop were similar in broilers subjected to feed withdrawal on litter or in crates and in broilers provided medicated or unmedicated feed before initiating feed withdrawal. Findings indicate that a decrease in the number of lactic acid producing bacteria in the crop and an increase in crop pH may be related to the reduction of anti-Enterobacteriaceae activity in the crop during extended feed withdrawal.

Animals↗

PubMed2000

Physical, chemical, and microbiological changes in the ceca of broiler chickens subjected to incremental feed withdrawal.

Trials were conducted to determine the effect of feed withdrawal on the weight, pH, native bacterial flora, and the persistence of Salmonella typhimurium in the ceca of market-age broilers. Broilers were provided medicated or unmedicated feed and then were subjected to feed withdrawal for 0 to 24 h in transportation crates or on litter. After feed withdrawal, broilers were stunned, bled, scalded, and picked. One cecum from each bird was aseptically removed and weighed. The cecum was then blended in 20 mL of distilled water, and the pH of the blended suspension was measured. The number of total aerobes, Enterobacteriaceae, S. typhimurium, and lactic acid bacteria in the suspension were enumerated on the appropriate bacteriological media. Results indicated that up to 24 h of feed withdrawal produced no significant change in cecal weight and that cecal pH varied by up to 0.3 units during feed withdrawal. There were significant increases in the population of Enterobacteriaceae during feed withdrawal in Trials 2 and 3, and there was a significant increase in the population of cecal aerobes in Trial 3. Feed withdrawal produced significant decreases in the population of lactic acid bacteria in all trials, but no significant change in the population of S. typhimurium occurred during feed withdrawal. There were no significant differences in cecal weight, pH, native bacteria populations, or S. typhimurium populations between broilers that were subjected to feed withdrawal on litter or in crates. Findings indicate that feed withdrawal does not always effectively evacuate the contents of the ceca and that the ceca of broilers subjected to feed withdrawal can remain a source of foodborne bacterial pathogens.

Animal Feed↗