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PubMed1997

Effect of intermittent activity on broiler production parameters.

The use of intermittent lighting in broiler production has been shown to result in spurts of activity that appear to reduce lameness. Because intermittent lighting is difficult to achieve in curtain-sided houses, the objective of this study was to determine whether simple equipment used to increase activity in broilers would improve production variables. At 1 d of age, 840 male broiler chicks were placed in 24 floor pens. The four treatments (six replicates of 35 chicks each) were as follows: 1) Control-standard feeders, 2) Ramps and Toys-birds had to climb a slight incline ramp to reach feeder and had a hanging mobile, 3) Ramps only, and 4) Toys only-standard feeders. Two trials were conducted. Weekly group weights and feed consumption were recorded. Mortality was recorded daily. At 6 wk of age, birds were bled, euthanatized, weighted, and scored for ascites and tibial dyschondroplasia (TD), and relative heart, liver, and spleen weights were obtained. Blood samples were analyzed for blood gases, hemoglobin, red blood cell count, and clinical chemistries were performed. In Trial 1, during Weeks 2, 3, and 4, treatments with ramps had significantly heavier average bird weight and significantly lower feed:gain ratios. In Trial 2, treatments with ramps had no difference in average BW; however, these groups consumed less feed, resulting in significantly lower feed:gain ratios. Cumulative mortality was decreased by ramp treatment in Trial 2. Toys decreased the incidence and severity of TD in Trial 2. In general, organ weights, blood gases, hematologies, and clinical chemistries were not affected by treatments. However, birds in treatments with ramps had significantly lower serum calcium and smaller hearts in Trial 1, and significantly lower serum cholesterol and smaller hearts in Trial 2.

Animal Husbandry↗

PubMed1997

Probabilistic neural network prediction of ascites in broilers based on minimally invasive physiological factors.

A Probabilistic Neural Network (PNN) was trained to predict ascites in broilers based on minimally invasive inputs (i.e., physiological factors that do not require the death of the bird). A PNN is a supervised, three-layer, artificial neural network that classifies input patterns (e.g., physiological data) into specific output categories (e.g., ascites or no ascites). The PNN inputs were O2 level in the blood, body weight, electrocardiogram (ECG), hematocrit, S wave, and heart rate of individual birds. These data were from three experiments that have been described previously (Roush et al., 1996a,b). The three data sets were pooled into a combined data set for a total of 170 observations. From the pooled data, a training set (117 birds), a calibration set (17 birds), and a verification set (36 birds) were extracted. The PNN was trained on the training data set. To prevent the PNN from overfitting the training data, the neural network was evaluated on its ability to make correct predictions of the calibration data set. At the point at which the neural network made the highest number of correct classifications for the calibration data set, the trained neural network was saved on the computer. When the PNN was applied to the complete data set, the sensitivity or proportion of the birds with ascites that the PNN correctly diagnosed was 0.97 (75/77 birds). The specificity or proportion of birds that the PNN made a correct diagnosis of not having ascites was 0.98 (91/93 birds). When the PNN was applied to the verification data set, which was not subjected to neural network training, the sensitivity was 0.95 (19/20) and the specificity was 0.88 (14/16 birds). Use of models developed with artificial neural networks may enhance the diagnosis of ascites in broilers. The results may be useful in choosing and developing broiler strains that do not have a propensity for ascites.

Animals↗

PubMed1997

Effect of dried solids of nejayote on broiler growth.

The purpose of the present study was to test the suitability of the solids of nejayote (a waste product from the tortilla industry) in diets for broilers. The nejayote was obtained from two different tortilla-making factories and the solids were obtained by centrifuge then dried in a hot-air drier. Diets were formulated to be isocaloric and isonitrogenous according to the NRC dietary requirements (1994). Nejayote solids were supplemented at 2, 4, and 6% of the diet. Results show that the content of protein and calcium in the dried solids of nejayote were 5 and 13%, respectively. The performance of broilers fed diets supplemented with dried nejayote did not differ from that of those fed the control diet. Therefore, it is concluded that nejayote solids are suitable for broiler feed and do not affect growth performance. Utilization of nejayote solids at higher levels is a possibility provided that no adverse effects on body weight, feed utilization, and feed:gain ratios are observed.

Animals↗

PubMed1997

Feather retention force in broilers ante-, peri-, and post-mortem as influenced by electrical and carbon dioxide stunning.

Stunning and slaughter trials were conducted to evaluate the influence of stunning method (electrical 50 V alternating current, CO2 gas: 0 to 40% for 90 s or 40 to 60% for 30 s) on feather retention force (FRF) in commercial broilers. Feathers from the pectoral, sternal, and femoral feather tracts were sampled with a force gauge before stunning (ante-mortem) and contralaterally either after stunning (peri-mortem from 0.5 to 4 min) or after stunning and bleeding (post-mortem from 2 to 6 min). Prior to stunning, ante-mortem FRF values varied among assigned stunning methods only for the pectoral (7%) feather tract. After stunning, peri-mortem FRF values were higher only for the sternal tract (11% for 40 to 60% CO2 for 30 s); whereas after stunning and bleeding, post-mortem FRF values were lower than ante- or peri-mortem only for the sternal tract (10% lower for 40 to 60% CO2 for 30 s). Peri- and post-mortem FRF values did not differ among stunning methods for the pectoral and femoral feather tracts. Small changes in FRF values occurred from ante-mortem to peri-mortem (-1 to +12%), and from ante-mortem to post-mortem (-2 to +8%) across stunning methods. A significant increase was determined for only the pectoral tract (7%) from ante- to peri-mortem across stunning methods. Electrically stunned broilers that were not bled gained weight in excess of the 36 feathers removed (0.16%), apparently due to body surface water pickup during the brine-stunning process, whereas CO2-stunned broilers lost weight due to excretion of cloacal contents (-0.31 to -0.98%). The change in body weight among stunning methods was significant (P < 0.0233). Peri- and post-mortem FRF, in addition to bleed-out body weight loss, were not substantially influenced by electrical or CO2 stunning methods, and, therefore, carcass defeathering efficiency may not differ after scalding.

Animals↗

PubMed1997

Effects of added lard fed to broiler chickens during the starter phase. 1. Body and selected organ weights, feed conversion, hematology, and serum glucose.

The effects of added lard in starter diets on BW, selected organ weights, feed conversion, hematological indices, and serum glucose were determined weekly in broiler chickens between 14 and 42 d of age. Nonisocaloric starter diets were formulated to contain either 0, 3, or 7% added lard, where the megacaloric percentages of all major nutrients were held constant. Broiler chickens received either 0, 3, or 7% added lard in starter diets through 10 d of age (S1), followed by either 3 or 7% added dietary lard through 21 d of age (S2). All possible combinations of the three S1 diets and two S2 diets yielded six total dietary treatments. A common grower diet was provided after 21 d. Body weight was not affected by diet and feed conversion did not increase between 21 and 42 d when birds were fed 3 or 7% added lard in the S1 diet. The effects of the S1 and S2 diets on relative liver weight were inconsistent over time and were not influenced by sex. Hematocrits were increased across time in birds fed 3% S1 diets and plasma protein concentrations were increased at 14 d in birds fed 7% S1 diets. It was concluded that the response of broiler chickens between 14 and 42 d to different levels of dietary lard was influenced by age of feeding during the starter period.

Animals↗

PubMed1997

The effect of a single or repeated period of high stocking density on the behavior and response to stimuli in broiler chickens.

Broiler chickens are normally housed at a fixed number per unit area throughout their life, which reduces their opportunity for movement during the later stages of rearing. An experiment is described that exposed broilers to a high stocking density either once or twice in the rearing period, and investigated the effects on the birds' behavior, and the response to other birds and humans after the second exposure to high or low stocking density. The stocking density was increased from a low level (1.7 kg/m2) to a high level (14 kg/m2) for the 2nd and/or 4th wk of rearing, or left unchanged at the low level. When stocked at the low rate, the birds spent more time walking and sitting and less time dozing and sleeping. They pecked more at inanimate objects and interacted more with other birds, but this did not include aggressive interaction. The effects of stocking density on behavior were greater in Week 4 than in Week 2, but there was no evidence that exposure to a high stocking density in Week 2 influenced the birds' behavioral response to a high stocking density in Week 4. Where stocking density did affect behavior in both Weeks 2 and 4, there was evidence of the response being cumulative. The activity of birds in the presence of another bird restrained in an open field arena was greatest when they had been stocked at the low density throughout the experiment. When a familiar person was in the arena, the birds that had been stocked at the high density in Week 2 were most active, but these birds showed the longest tonic immobility when inverted in a cradle. It is concluded that a high stocking density reduces activity in broiler chickens, and that birds stocked at a high density early in the rearing period are most active in the presence of people and show the longest tonic immobility in response to a fearful stimulus.

Aggression↗

PubMed1997

Replacement value of betaine for DL-methionine in male broiler chicks.

The effect of DL-methionine and betaine supplementation on growth performance of 2,400 male broilers in the age period of 1 to 38 d, and on carcass composition of a subsample of 384 birds was examined. Three dose levels of DL-methionine (0, 0.05, and 0.10%) and two doses of betaine (0 and 0.04%) were supplemented in different combinations to methioninedeficient diets. Two types of diets were fed as starters and growers: either corn-soybean diets or practical diets typical for the Dutch broiler industry. All diets were fortified with 220 ppm choline in order to avoid a deficiency in methyl groups. Increasing DL-methionine supplementation significantly improved daily weight gain and feed conversion efficiency. Supplemental betaine did not affect bird growth. Betaine slightly improved feed conversion in diets without supplemental DL-methionine, but did not affect this parameter in diets with added DL-methionine. Breast meat yield was significantly increased by about 1.5 percentage points by the addition of 0.05% DL-methionine, whereas 0.04% betaine only tended to increase breast meat yield in the range of 0.3 to 0.6 percentage points. The type of diet did not have any effect on the responses obtained. In summary, there was no evidence for betaine to spare DL-methionine as an essential amino acid supplement in broiler diets.

Analysis of Variance↗

PubMed1997

The effect of strain of broiler on physiological parameters associated with the ascites syndrome.

Differences among eight commercial broiler strains in factors indicating susceptibility to ascites were investigated. Chicks from eight crosses were obtained from two hatcheries (one was obtained from both hatcheries to give a total of nine) and raised to 6 wk of age on commercially prepared rations containing 3,300 kcal/kg energy with 24% protein to 3 wk of age and 20% protein from 3 to 6 wk. Each cross was represented by four pens of 90 broilers each. At 21 and 42 d, groups of 20 birds per pen were weighed and feed consumption was measured in order to calculate the feed conversion ratio. At 21 and 42 d, a blood sample was taken from two birds per pen to determine the hematocrit value. These birds were killed and dissected to determine heart, liver, lung, and spleen weights. Lung volume was determined by water displacement. Significant differences were observed between crosses for all of the measures with the exception of feed conversion ratio and mortality. These differences were most prominent for hematocrit value, which is an initial adaptation to anoxia, suggesting that broiler lines could be chosen that resist anoxic environmental conditions.

Animals↗

PubMed1998

The inhibitory effect of carboxymethylcellulose with high viscosity on lipid absorption in broiler chickens coincides with reduced bile salt concentration and raised microbial numbers in the small intestine.

Two diets, with or without a nonfermentable carboxymethylcellulose (CMC) with high viscosity, were fed to broiler chickens beginning at 2 wk of age to study whether the anti-nutritive effect of gelling fibers on lipid digestibility may be associated with reduced intestinal bile salt concentration. Moreover, the microflora were examined to study whether possible changes in bile salt concentration coincide with alterations in microbial numbers. Carboxymethylcellulose depressed apparent lipid digestibility (P = 0.021). Feed intake and weight gain were not significantly affected. Water intake was increased in birds fed the CMC diet (P = 0.039). Bile acid concentration in small intestinal digesta was decreased (P = 0.047) in birds fed the CMC diet, which may have been caused by the increased water content of digesta (P < 0.001). The concentration of bile acids per gram dry matter or per milligram chromium was not reduced in small intestinal contents. Broiler chickens fed the CMC diet excreted more bile acids in the excreta (P < 0.001). Total aerobic and anaerobic microbial counts in the intestinal digesta were significantly increased in the duodenum plus jejunum (P = 0.038) but not in the ileum. Significant increases were found in the numbers of Clostridia (P = 0.017), Lactobacillus (P = 0.009), Bacteroides (P = 0.022), and yeasts and molds (P = 0.012). The present study supports the hypothesis that a nonfermentable gelling fiber (CMC) decreases apparent lipid digestibility by reducing the concentration of bile acids in the chyme in broiler chickens. Moreover, the ingestion of gelling fibers may increase the bacterial activity in the small intestine, which may further contribute to malabsorption of lipids.

Animal Feed↗

PubMed1998

Physiological stress and welfare of broiler chickens in transit: solutions not problems!

The rearing of large numbers of broiler chickens at geographically dispersed sites means that they have to be transported by road, over various distances, to centralized processing plants for slaughter. The birds may be exposed to a variety of stressors during transit, including the thermal demands of the transport microenvironment. The thermal environments experienced by broiler chickens during routine transport in the U.K. on a large number of commercial vehicles under a wide range of external climatic conditions have been characterized using three-dimensional thermal mapping (temperature and water vapor density). Inadequate ventilation results in heterogeneous distributions of temperature and humidity and, thus, thermal loads within the vehicle, and, therefore, the existence of a "thermal core" in which the risk of heat stress is increased. Relationships between specific physiological indices of stress and quantified thermal loads have been determined in accurate transport simulations in the laboratory. The findings have been employed to establish a predictive model of the induction of heat stress during commercial transportation, as well as to define the acceptable ranges and limits for temperature and humidity within the transport containers. These principles have been utilized in developing a monitoring system to warn of impending heat stress and in improving vehicle design to facilitate the prevention of heat stress during broiler transportation.

Animal Welfare↗

PubMed1998

Lung lining fluid antioxidants in male broilers: age-related changes under thermoneutral and cold temperature conditions.

The purpose of this study was to determine age-related changes in lung lining fluid antioxidants in broilers reared under thermoneutral or cold temperature conditions. Male broilers (Cobb 500) were placed in floor pens within environmental chambers and fed a standard commercial starter diet. The thermoneutral Control chamber was maintained at 32, 30, 27, and 22 to 25 C for Weeks 1, 2, 3, and 4 to 7, respectively, whereas temperature in the Cold chamber was lowered to 18 C during Week 3 and maintained between 15 and 18 C for the rest of the study. At 2, 4, and 7 wk, four to six birds per chamber were selected randomly. The lungs were lavaged with heparinized saline (2 mL/g lung) to obtain lung lining fluid. Antioxidants [reduced (GSH), oxidized (GSSG), and total (TGSH) glutathione, uric acid, ascorbic acid, and alpha- and gamma-tocopherol] in lung lining fluid were determined by HPLC; protein was determined colorimetrically. In Controls, levels of alpha- and -gamma-tocopherol, uric acid, and GSH in lung lining fluid decreased between 2 and 7 wk of age. Birds in the Cold chamber exhibited higher protein, a higher GSSG:TGSH ratio, and a decrease in ascorbic acid (7 wk) in lung lining fluid relative to Controls. Lung lining fluid antioxidants were not correlated with antioxidants in plasma. To determine the effect of vitamin E supplementation on lung lining fluid antioxidants, birds were given a supplement of 200 IU alpha-tocopherol per day for 7 d. Alpha-tocopherol supplementation elevated alpha-tocopherol levels in lung lining fluid, but lowered ascorbic acid, GSH, and GSSG and had no effect on uric acid in lung lining fluid. The results of this study suggest that antioxidant protection in lung lining fluid may diminish with age, that cold conditions in this study produced an oxidative stress in lung lining fluid in broilers, and that oral supplementation of alpha-tocopherol elevated lung lining fluid alpha-tocopherol.

Aging↗

PubMed1998

In ovo administration of recombinant human insulin-like growth factor-I alters postnatal growth and development of the broiler chicken.

Two experiments assessed the efficacy of in ovo administration of insulin-like growth factor-I (IGF-I) to enhance skeletal muscle development and improve feed efficiency of broilers. Hatching eggs were divided into three groups: uninjected control, vehicle-injected control, and recombinant human (rh) IGF-I (100 ng per embryo). Eggs in Experiment 1 were injected on Day 1, 4, or one of Day 7 through 18 of incubation. Growth rates for Days 1 and 4 resulted in the greatest response to treatment (P < 0.01, P < 0.06 respectively). Based on these results, Experiment 2 focused on Days 1 to 4 of incubation. Results from Experiment 2 showed that there was no significant difference in hatchability among control and rh IGF-I treatment groups. Injection on Day 3 resulted in the greatest response for increased live (P < 0.035) and leg (P < 0.02) weights in both sexes. Feed efficiencies of all rh IGF-I groups were significantly (P < 0.01) improved for the first 3 wk. In ovo administration of rh IGF-I on Day 3 increased feed efficiency (6.65%; P < 0.009) in pens of mixed-sex broilers. In addition, live weights (12.3%; P < 0.002), leg weights (11.7%; P < 0.01), breast weights (9.9%; P < 0.04), and heart weights (11.4%; P < 0.02) were increased in males. These results demonstrate that in ovo administration of rh IGF-I alters feed efficiency, growth, and tissue development. This finding lends itself to significant improvements in broiler production efficiency and profitability.

Animal Nutritional Physiological Phenomena↗

PubMed1998

The infusion rate dependent influence of acute metabolic acidosis on pulmonary vascular resistance in broilers.

Experiments were conducted to evaluate the pulmonary vascular responses of lightly anesthetized clinically healthy male broilers during acute metabolic acidosis induced by bolus i.v. injections or constant i.v. infusions of HCl. In Experiment 1, broilers received consecutive 1.5 mL i.v. bolus injections of 2.5% mannitol (volume control) and 0.4 N, 0.8 N, and 1.2 N HCl in 2.5% mannitol. Following each injection, equivalent concentrations of mannitol or HCl were infused i.v. at a rate of 0.05 mL/min.kg BW. In Experiment 2, repeated bolus injections of 2.5% mannitol and 1.2 N HCl were administered during ongoing constant infusion of 2.5% mannitol. The following variables were evaluated: pulmonary arterial pressure, pulmonary vascular resistance, mean arterial pressure, total peripheral resistance, cardiac output, stroke volume, heart rate, respiratory rate, hematocrit (HCT), and arterial blood gas (PaO2, PaCO2, pH, HCO3-). Mannitol alone did not alter any of the variables. The HCl loading protocols acidified the arterial blood to sustained (constant infusion) or transient (bolus injection) values averaging between pH 7.2 and 7.3. In both experiments, bolus injections of 1.2 N HCl caused transient increases in pulmonary vascular resistance and pulmonary arterial pressure, coincident with decreases in mean arterial pressure and cardiac output. When HCl was infused at a constant rate in Experiment 1, the arterial blood hydrogen ion concentration, [H+], was positively correlated with pulmonary arterial pressure and cardiac output, negatively correlated with mean arterial pressure and total peripheral resistance, and was not correlated with pulmonary vascular resistance. During constant i.v. infusion of mannitol or HCl in both experiments, pulmonary arterial pressure was positively correlated with pulmonary vascular resistance and cardiac output. Overall, bolus injections of 1.2 N HCl consistently triggered transient pulmonary vasoconstriction (increased pulmonary vascular resistance), leading to a transient increase in pulmonary arterial pressure in spite of opposing changes in cardiac output and mean arterial pressure. In contrast, equivalent or greater increases in [H+] during constant i.v. infusion of HCl caused a substantially lower increment in pulmonary arterial pressure, which, in, turn was primarily attributable to increases in cardiac output rather than pulmonary vascular resistance. Increments in either pulmonary vascular resistance or cardiac output induced by metabolic acidosis would be expected to contribute to the onset of pulmonary hypertension syndrome (PHS, ascites) in broilers.

Acidosis↗

PubMed1998

Effect of yeast-supplemented feed on Salmonella and Campylobacter populations in broilers.

The effect of the yeast, Saccharomyces boulardii, on experimental cecal colonization of broilers with Salmonella typhimurium and Campylobacter jejuni was investigated. Duplicate pens of broiler chicks were given ad libitum access to a standard feed supplemented with no yeast (control), or 1 g (1x), or 100 g (100x) dried S. boulardii/kg feed. All chicks except negative controls were challenged on Day 4 with 3.2 x 10(8) cfu S. typhimurium and 6.5 x 10(8) cfu C. jejuni by oral gavage. After 3 wk, the broilers were euthanatized and ceca were aseptically removed and analyzed for Salmonella and Campylobacter. Frequency of Salmonella colonization was significantly (P < 0.05) reduced due to yeast treatment. Of the positive control birds, 70% were colonized with Salmonella; whereas only 20 and 5% of the 1x and 100x yeast-treated birds were colonized. Mean number of Salmonella per gram of ceca and contents were log 1.64, 0.35, and 0.15, respectively, for the control, 1x, and 100x yeast-treated birds. Campylobacter colonization was not significantly affected by yeast treatment. Similar results were obtained from a second trial conducted in larger isolation floor pens.

Animal Feed↗

PubMed1998

Self-selection of dietary protein and energy by broilers grown under a tropical climate: adaptation when exposed to choice feeding at different ages.

Three hundred broiler chicks (Hubbard) of both sexes were assigned to five feeding treatments: T0 received a complete diet (control), T1 was a choice feeding system with simultaneous access to an energy-rich feed (ground corn) and a protein concentrate (43.7% CP), and T2, T3, and T4 were introduced to choice feeding after 1, 3, and 5 wk, respectively, of consuming the complete diet. At 1-d-old, T1 chicks showed a marked preference for corn, with only 21.4% of their intake being the protein concentrate diet. Intake of the concentrate progressively increased to 40 to 45% after 3 d of adaptation, resulting in diets with 22.5 to 24.3% CP. When broilers fed the complete diet for 1 to 5 wk (T2, T3, T4) were changed to choice feeding, on the 1st d, their feed choice intake was similar to that of T1 chicks at the same age. Visual observation and tactile assessment of the feed particles during the initial period allowed the chicks to quickly evaluate the new feeds and to adapt their feeding behavior. Although total feed intake to 6 wk of age was not significantly affected by the feeding treatments, broilers on choice feeding selected diets with a lower percentage of CP and had lower live body weights at 6 wk than those fed the complete diet (T0).

Adaptation, Physiological↗

PubMed1998

Evaluation of transgenic event 176 "Bt" corn in broiler chickens.

A 38-d feeding study evaluated whether standard broiler diets prepared with transgenic Event 176-derived "Bt" corn (maize) grain had any adverse effects on male or female broiler chickens as compared to diets prepared with nontransgenic (isogenic) control corn grain. No statistically significant differences in survival or BW were observed between birds reared on mash or pelleted diets prepared with transgenic corn and similar diets prepared using control corn. Broilers raised on diets prepared from the transgenic corn exhibited significantly better feed conversion ratios and improved yield of the Pectoralis minor breast muscle. Although it is not clear whether this enhanced performance was attributable to the transgenic corn per se, or due to possible slight differences in overall composition of the formulated diets, it was clear that the transgenic corn had no deleterious effects in this study.

Animal Feed↗

PubMed1998

A deterministic model for the economic evaluation of broiler production systems.

A deterministic model for the economic evaluation of broiler production and the derivation of economic values in broiler breeding was developed and tested. The model distinguishes four production stages: multiplier breeder, hatchery, commercial grower, and processor. The processor is included to determine relationships for the price per kilogram of live weight and the quality of the carcass, either on a "whole sale" or "further processed" base. Quantity of product output for the system is fixed by a predetermined amount of kilogram carcass of final product broilers finished by the commercial grower. Profitability of production and cost prices per unit product for subsequent stages can be calculated. Exogenous parameters are easily changeable in order to calculate profitability and cost prices for different production levels or production circumstances. Economic values can be derived considering influences of changes in genetic merit for performance traits on profitability or cost price, for integrated and nonintegrated production systems. By changing exogenous parameters, the model can also be used to analyze profitability or derive economic values for other meat-type poultry, such as turkey.

Agriculture↗

PubMed1998

Heterogeneity of staphylococci and other bacteria isolated from six-week-old broiler chickens.

In broiler operations, various health problems develop during the final 2 wk of the growing period, resulting in increased mortality and condemnation losses. At this stage, sickly birds were found to be systemically infected by various bacteria regardless of varied clinical signs, and the purpose of this study was to carry out thorough microbiological investigations on this problem. Thirty-one 6-wk-old broilers showing signs of illness were obtained from three farms, and bacterial isolations were carried out from the blood, liver, and hock joint. Bacteria were isolated from 87, 90, and 71% of the blood, liver, and hock joint samples, respectively. Mean bacterial counts in log10 of the blood (per milliliter) and liver (per gram) were 2.15 and 2.93, respectively. Among 132 bacterial isolates, major species were Staphylococcus (60%), Corynebacterium (18%), Escherichia coli (5%), and Stomatococcus (4%). Among 79 Staphylococcus isolates, 77 were coagulase-negative. Major species of staphylococci were S. lentus (19%), S. simulans (18%), S. cohnii (13%), S. gallinarum (10%), and S. captis (7%). In addition, six species of gram-positive and five species of gram-negative organisms were isolated. Thus, the apparent systemic infections were not caused by predominant pathogenic bacterial species, and adequately described as mixed infections. There were some significant relationships between isolated bacterial species and sampling sites, suggesting that certain organisms were abundant in the environment of a particular poultry house. These results indicate that systemic infections in market age broilers are caused by mixed bacterial species and suggest that they are caused by suppressed host antibacterial systems rather than pathogenic factors of microorganisms.

Animals↗