Ectopic cartilaginous and osseous lung nodules induced in the young broiler by inadequate ventilation

Morphometric and histologic changes in the pulmonary system of broilers raised at simulated high altitude

Broilers were reared in conditions of hypobaric hypoxia (3500 m altitude) to investigate the development of pulmonary nodules in birds reared in hypobaric hypoxia and judged by clinical observation to be developing broiler pulmonary hypertension syndrome (BPHS); in unaffected birds reared in hypobaric hypoxia; and in birds reared at ambient atmospheric pressure. Gross pulmonary morphometric measurements, packed cell volume, electrocardiogram QRS amplitude and body weight also were compared among the three experimental groups. Results indicate that hypobaric hypoxia alone exercised little influence on the development of pulmonary nodules. Nodule numbers per section and nodule area per section were numerically greater in birds reared in hypobaric hypoxia, but there were no consistent significant differences in nodule numbers in birds which developed BPHS. As expected, absolute lung length, inter-rib distance and lung volume increased significantly with increasing age and size; but when these parameters were expressed as a function of body weight, they decreased with increasing age. Again, intergroup differences were inconsistent. Packed cell volume and electrocardiogram QRS amplitude were significantly increased in birds reared in hypobaric hypoxia.

Identification of tissue hypoxia in the livers of ascitic and hypoxia-induced broilers using trypan blue

1. The perfusion of livers with the vital dye trypan blue was performed to test for evidence of tissue hypoxia in 3 groups of young broiler chickens, namely, ascitic, hypoxia-induced and controls. 2. Hepatocytes that stained with trypan blue were considered to be dead or dying before fixation and represented damaged cells. 3. The proportion of trypan blue-stained hepatocytes in the livers of ascitic birds was slightly less than half that observed in the hypoxia-induced birds but significantly more than the proportion of stained cells observed in control birds. 4. Liver damage in the ascitic birds was also assessed biochemically by an altered enzyme profile. 5. The study demonstrated that increased trypan blue uptake in the livers of ascitic birds reared at sea-level may be the consequence of hypoxia stress caused by reduced oxygen utilisation.

Pulmonary arteriole hypertrophy in broilers with pulmonary hypertension syndrome (ascites)

Two experiments were conducted to determine the effect of low ventilation or cool temperature environments on pulmonary arteriole hypertrophy. Male broilers were maintained under control or low ventilation conditions in Experiment 1, whereas male broiler breeder by-product chicks were exposed to cool temperature conditions in Experiment 2. Birds were randomly selected for histological evaluation of lung tissue in both experiments. In Experiment 1, birds that had pulmonary hypertension syndrome (PHS+) exhibited a greater degree of inflammation of lung tissue at 5 and 7 wk of age than controls or birds that did not have PHS (PHS-). These PHS+ birds also had higher numbers of cartilaginous osseous nodules at 3 and 7 wk of age than controls. Morphometric analyses revealed that PHS+ birds in Experiment 1 had a thicker medial layer associated with 100 to 200 microns diameter pulmonary arterioles at 7 wk of age, and 50 to 100 microns arterioles at 3 and 7 wk of age than PHS- or control birds. In Experiment 2, PHS+ birds exhibited a thicker medial layer in pulmonary arterioles at 7 wk of age than did PHS- birds, but there were no differences in medial layer thickness at 5 wk of age nor were there differences in the degree of inflammation or amount of osseous nodule formation between PHS+ and PHS- birds at 5 and 7 wk of age. Thus, pulmonary arteriole hypertrophy was observed in birds having PHS in response to both low ventilation and cool temperature environments and this hypertrophy occurred with or without a coincident inflammatory response in lung tissue.

Effect of alpha-tocopherol on antioxidants, lipid peroxidation, and the incidence of pulmonary hypertension syndrome (ascites) in broilers

Research has demonstrated a compromised antioxidant capacity in broilers with pulmonary hypertension syndrome (PHS). Thus, the objective of the present study was to assess the effects of vitamin E on PHS-induced mortality, tissue antioxidants, and plasma lipid peroxides in male broilers. Control broilers were provided normal ventilation but others, maintained under low ventilation conditions to induce PHS, were randomly assigned to nonimplanted (NI), placebo (PL), or vitamin E (VE) implanted groups. The VE implant released a total of 15 mg of alpha-tocopherol from 0 to 3 wk of age. Tissues and blood samples were obtained at 3 and 5 wk of age from birds with (PHS+) and without (PHS-) PHS. Five-week PHS cumulative mortality was lowered by alpha-tocopherol with mortality rates of 3.6, 4.2, 11.9, and 11.8%, for Controls, VE, NI, and PL groups, respectively. The PHS+ birds exhibited lower body weights, higher hematocrit, right ventricular hypertrophy, lower alpha-tocopherol and glutathione (GSH) concentrations in liver and lung, as well as indicators of oxidative stress, including elevated plasma lipid peroxides and lower oxidized GSH in liver and erythrocytes, at 5 wk of age. All birds exhibited lower erythrocyte catalase activity at 5 than at 3 wk of age. An improved antioxidant capacity was observed in VE birds, including higher liver and lung alpha-tocopherol at 3 and 5 wk, higher liver GSH at 3 wk, and lower plasma lipid peroxide values at 5 wk of age. Direct correlations observed between body weight and plasma lipid peroxides at 3 wk (r = .45) and between right ventricular hypertrophy and plasma lipid peroxides at 5 wk (r = .48), suggests that lipid peroxidation plays a role in the etiology of PHS. The results indicate that the VE implant was effective in lowering PHS-induced mortality in broilers apparently by attenuating processes leading to lipid peroxidation.

Haematology and histopathology of seven-week-old broilers after early food restriction

The haematology and histopathology of seven-week-old broilers were examined after periods of early food restriction, for six, 10 or 14 days from six days old. After several weeks on an ad libitum diet the birds failed to compensate for the weight lost during early food restriction. Immediately after the periods of food restriction, the birds demonstrated significantly increased heterophil/lymphocyte ratios, reduced eosinophils and slightly raised basophil counts. At seven weeks old, a significant reduction was seen in red and white blood cells and thrombocyte numbers together with significant increases in mean cell haemoglobin and mean cell volume. The haematological profile demonstrated a macrocytic normochromic anaemia caused possibly by a folic acid deficiency as a result of the food restriction. Histopathological lesions were seen in the heart, lungs and liver from birds on all diets but there were more lesions the longer the food had been restricted. Lung disease was more marked where there was inadequate ventilation. Cartilaginous and osseous lung nodules were significantly fewer after food restriction. It was postulated that the increase in pathological lesions in the food-restricted birds may be associated with a stress response.