Biomedical subjects

Y Vizzier-Thaxton

Publications and source records attributed to Y Vizzier-Thaxton.

10 recordsLinked to original sources

PubMed2006

Apparent attachment of Campylobacter and Salmonella to broiler breeder rooster spermatozoa.

It has been demonstrated that horizontal and vertical transmission of Salmonella and Campylobacter can occur in broiler breeder flocks. The mechanism of this transmission is still unclear. Previously negative broiler breeder flocks have been reported to become positive with Salmonella, Campylobacter, or both after the introduction of "spike" roosters at 45 wk of age. To determine whether the rooster semen is a possible source of transmission to hens for colonization, we evaluated the association of both Salmonella and Campylobacter spp. to segments (head, midpiece, and tail) of individual spermatozoa after artificial inoculation. Salmonella typhimurium, Salmonella heidelberg, and Salmonella montevideo, or Campylobacter jejuni (in 0.85% saline) was added to a freshly collected (by abdominal massage) aliquot of pooled semen from roosters housed in individual cages. The semen and bacteria solutions were incubated 1 h at room temperature. Samples were fixed using Karnosvsky and Zamboni fixatives for 24 h prior to centrifuging and rinsing in 0.1 M cacodylate x HCl buffer. Individual aliquot samples were then subjected to both scanning (JSM-5800) and transmission (JEM-1210) electron microscopy. The scanning electron microscopy showed that Salmonella was associated with all 3 segments (head, midpiece, and tail) of the spermatozoa and apparently equally distributed. Campylobacter was mainly associated with the midpiece and tail segments; few isolates were located on the head segment. The transmission electron microscopy showed apparent attachment of Salmonella and Campylobacter to the spermatozoa.

Animals↗

PubMed2006

Physiological stress in laying hens.

Stress responses in laying hens were mediated by continuous infusion of adrenocorticotropin (ACTH) via osmotic pumps. The ACTH was dissolved in saline solution (0.85%), and each pump delivered 8 IU of ACTH per kilogram of BW per day at the rate of 1 microL/h for 7 d. Control hens received pumps loaded with saline. Measurements were made at 6 d postpump implantation, unless otherwise indicated. The ACTH-treatment increased BW and total carcass, rear half of carcass, intestinal, and liver weights. Proximate analyses of liver showed increases in dry weight, moisture, protein, fat, carbohydrate, and ash content. Weights of the front half of the carcass, as well as weights of the abdominal fat pad, heart, head, feet, and skin were unaffected by ACTH-treatment. Plasma corticosterone, glucose, cholesterol, and high-density lipoproteins were increased by ACTH, whereas triglycerides were decreased. Feed and water intake, total excreta, and excretory DM were all increased in ACTH-treated hens. The ACTH decreased carbohydrate in excreta, whereas ash, protein, fiber, and gross energy of excreta were unaffected. The ACTH did not affect digestibility of dry matter, proteins, carbohydrates, fats, or gross energy; however, absorption of ash, protein, carbohydrates, and gross energy were increased by ACTH. Antibody levels to sheep red blood cells, cell-mediated immunity (wattle index to phytohemagglutinin-phosphate), and relative spleen weight were reduced by ACTH, whereas heterophil:lymphocyte ratio was increased. Reproduction in hens was negatively affected by ACTH treatment, as measured by cessation of laying on the third day of treatment, atretic follicles, and decreased oviduct weight.

Adaptation, Physiological↗

PubMed2006

Stocking density and physiological adaptive responses of broilers.

Three trials were conducted to assess the effects of stocking density on physiological adaptive responses of broilers. Male broilers were reared in floor pens under conditions similar to those used commercially in the United States. Accepted indicators of adaptation to a stressor were measured on d 49 including plasma concentrations of corticosterone, glucose, cholesterol, and total nitrites as an indicator of nitric oxide, as well as heterophil:lymphocyte ratio. In trial 1, calculated stocking densities were 20, 25, 30, 35, 40, 45, 50, and 55 kg of BW/ m2 and in trials 2 and 3, stocking densities were 30, 35, 40, and 45 kg of BW/m2. Stocking densities were calculated based on a final BW of 3.3 kg. Linear trend analyses were used to assess the role of stocking density on each of the physiological parameters. Results indicate that stocking density did not cause physiological adaptive changes indicative of stress.

Adaptation, Physiological↗

PubMed2005

Stocking density effects on growth performance and processing yields of heavy broilers.

This study examined responses of male broilers during a 49-d production cycle to 4 placement densities in 2 trials. Trials were pooled because no treatment x trial interaction occurred. In each trial, 1,488 male chicks were randomly placed into 32 floor pens to simulate final densities of 30 (37 chicks/pen), 35 (43 chicks/ pen), 40 (50 chicks/pen), and 45 (56 chicks/pen) kg of BW/m2 of floor space based on a projected final BW of 3.29 kg. Growth rate and nutrient utilization were similar (P > or = 0.05) among the treatments from 1 to 32 d of age. From 1 to 49 d, BW gain (P = 0.011) and feed consumption (P = 0.029) were adversely affected by increasing the placement density from 30 to 45 kg of BW/m2 of floor space. The reduction in cumulative BW gain due to placement density can be partially explained by less feed consumption as evidenced by 95.4% of the sums of squares of BW gain being attributable to feed consumption. Litter moisture content (P = 0.025) and foot pad lesion score (P = 0.001) increased linearly with increasing placement density. Upon processing, whole carcass and breast meat yields relative to BW were not affected (P > or = 0.05) as density increased from 30 to 45 kg/m2. The proportion of whole carcasses with scratches, but not tears, on the back and thighs increased (P = 0.021) as density increased. These results indicate that increasing the density beyond 30 kg/m2 elicited some negative effects on live performance of heavy broilers.

Animal Husbandry↗

PubMed2002

Bacteria in heart and lungs of young chicks.

AIMS: The purpose of these experiments was to determine whether the heart and lungs of young chicks harboured bacteria. METHODS AND RESULTS: Samples of the heart and lungs were aseptically removed from chicks on scheduled sampling days. Experiment 1 showed that of the 360 birds evaluated during the late embryonic and early post-hatching periods, only 10.8% harboured bacteria in the heart, lungs, and heart and lungs simultaneously. Experiment 2 suggested that bacteria in these organs were transient. Twenty-three bacterial species were found in the hearts whereas 30 were found in the lungs. Experiment 3 showed that only 1.4% of embryos harboured bacteria in the yolk, albumen, heart and lungs whereas 12.9% of the embryos had bacteria in the air cell. CONCLUSIONS: During the post-hatching period, there was a higher incidence of bacterial isolation in the heart and lungs, whilst during the embryonic development period, there was a lower incidence of bacterial isolation from these two organs. Results suggested that the heart and lungs do not have a residual bacterial flora; rather, opportunistic bacteria occasionally pass through these tissues. SIGNIFICANCE AND IMPACT OF THE STUDY: These experiments proved that bacteria could be isolated in the heart and lungs of healthy chicks reared from E17 to 3 weeks of age.

Animals↗

PubMed2002

Biochemical and immunological changes in chickens experiencing pulmonary hypertension syndrome caused by Enterococcus faecalis.

Recent studies have proven that Enterococcus faecalis (1.5 x 10(7) live bacteria from a tryptic broth culture given s.c. or intra-abdominally (IA) to 5-wk-old broilers) caused pulmonary hypertension syndrome (PHS) in 97% of the birds within 48 h. Definitive diagnosis of PHS was made at necropsy by observing a cavity on the surface of the right ventricular wall and by increased ratio of left ventricular weight to total ventricular weight. A nonlethal method of diagnosing PHS would enhance the study of PHS and alert production poultrymen to the onset of ascites (waterbelly), which is the cuLminating event of PHS. In the present study, serum hemoglobin, glucose, protein, cholesterol, aspartate amino transferase (AST) and creatine kinase-MB (myocardial in origin) enzymes, differential leukocyte numbers, and specific antibody levels against Ent. faecalis were evaluated as nonlethal diagnostic indicators of PHS. Decreases in serum protein and cholesterol of 3 and 10%, respectively, plus increases in percentages of basophils and monocytes of 18 and 40%, respectively, appear to indicate that PHS has been initiated. An agglutinating antibody, specific against Ent. faecalis, but not against other closely related bacteria, has been developed. Presence of this antibody in a bird means that the bird has previously encountered Ent. faecalis. Thus, this antibody may become a diagnostic for PHS in fast-growing chickens.

Animals↗

PubMed2002

Morphological changes in heart and lungs of broilers experiencing pulmonary hypertension syndrome caused by Enterococcus faecalis.

In a previous report, a method of identification of birds experiencing early symptoms of pulmonary hypertension syndrome (PHS) caused by challenge with Enterococcus faecalis was delineated. This method involved subjective heart scores based on visual observation of a cavity on the external surface of the right ventricular wall (RVW), as well as tonicity and thickness of this wall. Accuracy in identifying birds 48 h postchallenge with E. faecalis was acceptable. However, this method did not attempt to offer other morphological or physiological characteristics for further understanding the etiology of PHS. In the present study, three trials were conducted to establish morphological characteristics of the heart from birds challenged with E. faecalis. In Trials 1 and 2, discrepancies were found in heart length (HL) and thickness of the RVW. In Trial 3, the dry weight of the right ventricle (RV) increased after challenge with E. faecalis, as was the ratio of the mass of the RV to the mass of the total ventricle (TV). Histopathological evidence of hearts and especially lungs of birds challenged with E. faecalis were suggestive of PHS. Results indicated that RV, RV:TV ratio, and histopatholgical evaluation of heart and lungs are complementary to diagnosis of PHS.

Animals↗

PubMed2002

Pulmonary hypertension syndrome in young chickens challenged with frozen and autoclaved cultures of Enterococcus faecalis.

Enterococcus faecalis, when administered in a growth medium or sterile saline, will cause pulmonary hypertension syndrome (PHS) in chickens. The objective of this study was to determine if frozen and/or autoclaved cultures of E. faecalis retain ability to evoke PHS. In Trial 1, chicks were inoculated with 3.6 x 10(7) E. faecalis (IA) in tryptic soy broth (TSB) from either a live culture or one that had been autoclaved (120 degrees C for 20 min). Controls received TSB. Autoclaved and live cultures produced the same degree of PHS in a majority of the birds. Trial 2 used the same protocol, except a frozen (-70 degrees C for 60 min) culture of E. faecalis was compared with the control. The results agreed with those of Trial 1, i.e., the frozen culture also produced PHS. Trial 3 was conducted to determine if E. faecalis caused PHS by producing and releasing some unknown substance into the supernatant. Incidence of PHS was based on percentage of birds exhibiting ascites fluid at 24 hr after challenge. Controls received sterile, frozen, or autoclaved TSB. As compared with controls, those birds that received challenge with E. faecalis alone, supernatant alone, and E. faecalis plus supernatant from live cultures exhibited similar incidence of ascites, whereas birds that received E. faecalis plus supernatant and supernatant alone from cultures that had been either frozen or autoclaved exhibited elevated incidence of ascites as compared with controls. Also, with frozen and autoclaved cultures, those birds that received only pelleted E. faecalis exhibited incidence of ascites that did not differ from controls. Apparently, E. faecalis produces PHS in chicks by producing and releasing an unknown toxin.

Animals↗

PubMed2001

Stress and nutritional quality of broilers.

Broiler chicks were reared in environmental chambers. All birds were started under ideal conditions, i.e., 30.6 C with 35% RH. Beginning at Day 36, half of the chicks were maintained at 24 C and 35% RH. The other half were subjected to a cyclic temperature-RH regime that approximated a typical August day in central Mississippi (heat treatment). Half of each of the described groups received implants of osmotic pumps that released adrenocorticotropin (ACTH) at 8 IU/kg BW/d for 7 d. The remaining birds received placebo pumps. The main effects of ACTH and heat treatments were similar. Both treatments caused reductions in BW, carcass weight (CW), carcass protein (CP), and muscle calorie (C) content. ACTH, but not heat, reduced carcass moisture (M). Carcass fat and ash, however, were not affected. Most changes were not reversed after 1 wk of recovery. Although visible signs of pale, soft, exudative muscle (PSE) were present, "white" areas of muscle were absent. The decreased meat yield and detrimental changes in meat quality suggest that stress, whether induced hormonally or by exposure to over-heating, caused losses that were as severe as those associated with PSE under field conditions.

Adrenocorticotropic Hormone↗

PubMed2001

Pulmonary hypertension syndrome in broilers caused by Enterococcus faecalis.

A field strain of Enterococcus faecalis was administered to broiler chicks at doses of 0, 3 x 10(6), 1.5 x 10(7), and 2 x 10(7) bacteria/bird either intra-abdominally or intravenously. In trials 1 to 3, birds were reared communally in a broiler house on pine shaving litter. In trial 4, challenged and control birds were maintained in separate isolation rooms in metal cages with raised wire floors. Challenged birds exhibited a characteristic cavity or depression in the external wall of the right ventricle. A subjective scoring system was devised to quantify challenge effects by assigning each heart a score of 1 to 4. The average number of birds, over all trials and over all dose levels, exhibiting the ventricular cavity was 93%. This value in controls was 5%. The average heart score for challenged birds was 3.1, and that for controls was 0.20. Heart scores of challenged and control chicks were not different in birds reared communally or in separate isolation rooms. Additionally, both routes of administration were equally effective. Results suggest that challenge with E. faecalis caused pulmonary hypertension.

Animals↗