93 lung fragments were taken from 31 calves, aged approximately from 1 to 2 years, with pulmonary lesions in order to define the nature of the lesions and to highlight the prevalence of respiratory diseases in young bulls. Results showed a prevalence of 4.67%. The seasonal impact of the lesions has been highly marked. Whatever the season, the most common lung injury is red hepatization injury (or consolidation) (38.70%) followed by grey hepatization (6.45%), emphysema (19.35%), pneumonia (32.25%) and finally bronchopneumonia (3.22%). Our study showed that lesions were preferentially localized in the right apical lobe. This investigation demonstrated the strong spread of atypical pneumonia in the cattle population (young bulls) at the slaughterhouse of Batna justifying stunting and losses recorded in cattle farms of the region. For this, it was deemed urgently the appreciation of the extent and severity of macroscopic and microscopic tissue changes in order to limit this increased infection.
The respiratory diseases constitute a serious and major problem as well as for breeders than for veterinarians, because of the major economic losses they cause, and the expenses of care and preventions that they generate. In comparison to other domestic species, cattle seem particularly to be the most susceptible to inflammatory pulmonary disease, possibly because of multiple factors including anatomic peculiarities and functional differences in pulmonary defense mechanisms (Lay and Slauson, 1982). Lungs are the most exposed organs to different aggressions because of their anatomical and histological particularities. The deterioration of the hygienic conditions is the most important factor that aggravates and promotes pulmonary diseases (Belkhiri et al. 2014). Development of new vaccines and antibiotics does not seem to decrease the losses endorsed. The problem is related to younger and lighter-weight cattle with no preconditioning management in the feedlot. These animals are very susceptible to stress and thus predisposed to respiratory disease (Romero et al., 2012).
In Algeria, we do not have any precise statistics on bovine pulmonary diseases frequency, and no deepened survey has been led on their epidemiology. However, it appeared interesting for us to lead an investigation on these pulmonary diseases from information’s taking at slaughterhouses in order to well know them and especially to determine their real prevalence. The aim of this study was therefore to identify some gross and histopathological lesions in the affected lungs of calves in Batna’s slaughterhouse, Eastern Algeria.
Material and Method
The study consists of a prospective investigation, focused on calves slaughtered in Batna’s slaughterhouse over a period from December 2013 to May 2014. Batna city is located northeast of Algeria in the Aures’ region. The junction of two atlases (Tell and Saharan) which determines a climate of a semi-arid region ad forms the territory of this province. In winter, temperatures drop below zero at night, often with frost. During the summer, temperatures can reach 45 ° C in the shade and average rainfall is 210 mm per year.
This city is an agricultural region with a potential of cattle farms of about 71.806 heads. In addition, 38.720 dairy cows supplied by the Agricultural Services of Batna.
Organization and Working
The investigation has been realized on 31 bovines exclusively males aged less than 2 years of different breeds from Batna’s slaughterhouse. For every animal, lungs were carefully examined in this work.
Animals are slaughtered and eviscerated on the floor. The number of bovine slaughtered is about 10 to 15 daily. This variability is a function of seasons, religious festivals, economic conditions.
Lungs samples were collected from congested, healthy and between injured and healthy tissues in a 10% solution of formalin. The examination has been achieved macroscopically and microscopically. The macroscopic examination was a superficial observation of the organs, especially on the visceral and diaphragmatic faces and a deep observation at incision. All the samples were kept in an icebox and transported to the laboratory.
During this investigation, 93 lung tissues were sampled. The formalin fixed tissues were processed for paraffin embedding technique. The tissues were properly trimmed, washed in running tap water, dehydrated in graded ethanol, cleared in benzene and embedded in paraffin wax (melting point 60-620C). The sections were cut at the thickness of 3-4 mm and stained with haematoxylin and eosin (Luna, 1968).
Results and Discussion
Prevalence of Pulmonary Lesions
From December 2013 to May 2014, 1673 slaughtered cattle were examined at Batna’ slaughterhouse. Among them, 145 calves showed infectious lesions but only 31 calves showed infectious pulmonary lesions, of varying nature and severity (usually consisting of parenchymal consolidation mainly affecting apical lobes).
Results showed a prevalence of 4.67%. Our data seem to reach those of Karimkhani et al 2011.,with a rate of 10% and Shafique et al., with 15.99%. Furthermore, this rate is not far from respiratory infections frequencies over the last two years (2012 and 2013) of about 8.55% and 6.65 % respectively (from the registry data of Batna’s slaughterhouse). This prevalence was not higher during the period from January to September 2014, and doesn’t exceed 9.52%. The prevalence of lesions was far below the data recorded in similar studies; Mwenedata reported a prevalence of 62.87% and Belkhiri estimated 88.96% of lung lesions at Tiaret’s slaughterhouse. This low rate can be explained by the fact that the animals the subject of this study are all bulls of 1-2 years while the studies of Mwenedata and Belkhiri were carried out on slaughtered cattle often at an advanced age and therefore they are much more exposed to many risk factors that can cause lung damage. These factors can be biological ones (viruses, bacteria, parasites) and / or environmental causes (toxics, dusts) which may cause various lesions observed both macroscopically and microscopically.
Prevalence of Lung Lesions Depending on Season
Seasonal variations have a significant effect on the respiratory system of young animals. The study was conducted in two seasons- winter and spring. Indeed, peak lesion was observed during the winter with 61.29% versus 38.70% in the spring. In this study, pneumonia was recorded during the rainy season and thus agrees with Ahmed et al., .This is certainly due to the weakening of the resistance of the organism or the respiratory system caused by adverse environmental factors such as- the cold which seems to inhibit or lower the mucociliary clearance (Surfactant) and the activity of the alveolar macrophages, and it exerts a bronchial peripheral vasoconstriction with congestion of the respiratory mucosa. The relative humidity of the air increases the effects of cold, depresses the activity of macrophages and decreases the production of antibodies. Relative humidity in the housing can affect bacterial and viral concentrations. The calf housing at 50 to 60% relative humidity had lower bacterial concentrations than the housing similar to 80 percent relative humidity (Jubb et al., 1993; Jones and Hunt, 1983).
It was noted that, whatever the season, the most common lung injury is pulmonary hepatization. It represents 45.16% of lesions observed and joins the result of Tijjani et al. 2012, .Pneumonia ranks second with 32.25% followed by emphysema (19.35%). The proportion of bronchopneumonia was 3.22%. In the study conducted by Mwenedat, 2009 and Belkhiri 2010 the share of emphysema was higher (12.76% and 56% respectively), then comes atelectasis (2.08% and 20% respectively). The hepatization comes third for Belkhiri, 2010 while for Mwenedata, 2009 pleurisy was observed with a rate of 16%.
Definition of Studied Lung Injury
The lung lesions encountered at the slaughterhouse were classified according to their importance, based on bibliographic data. The distinction is made primarily on the macroscopic appearance of the lesions (Fig. 3). Different lesions sometimes sat on the same lung, only dominant lesion has been considered (Tegtmeier et al. 1999).
Fig.1: Red Hepatization lesion
Fig.2: Pneumonia injury
Fig.3: Pulmonary emphysema injury and abscess
Fig.4: Lung with atelectasis lesion
Fig.6: Pulmonary hepatization
Fig.7: Pulmonary hepatization with fibrous tissue
Fig.4 shows Alveoli (A) and air sacs (S) with no intra alveolar cells; the inter alveolar walls are fairly thin with absence of cellular elements in the light of the alveoli. A normal lung is showing in the Fig. 5 with characteristic honeycomb appearance, inter alveolar walls are thin down are observed, dotted lines and alveolar characteristic appearance of lung tissue is absent. The alveoli are collapsed and the alveolar lumen is absent and the presence of lymphocyts (L) is also observed. There is a total absence of the pulmonary alveoli at this histological section (figure 6), which prevents gas exchange of the lung tissue. There are also normal vasculatures with high lymphocytic infiltration. Pulmonary hepatisation is present with the loss of spongy structure of the lung. The light of the cells is completely absent where only fairly small spaces appeared. The figure 7 shows the presence of fibrous tissue (F) of lung parenchyma. Similarly, there is presence of lymphocyte infiltration of the lung tissue.
From the results of this study, it maybe concluded that hepatization (red and grey) was the most prevailing cattle lung lesion, thus the slaughterhouse is the best location for monitoring the evolution of lung damage, because slaughtered animals are belonging to the non controlled private sector animals. The seasonal impact of the distribution of the different lesions was important.
Source of Funding
Laboratoire ESPA, Veterinary Department, Batna 1, University
Conflict of Interest
We declare that we have no conflict of interest.