Studies on the Aetiology and Pathology of Calf Mortality in Buffalo and Cow Neonates

Abstract

This study was concluded on 325 neonates of Nili Ravi buffalo and 354 of Sahiwal cows maintained at the Livestock Production Research institute, Bahadurnagar during 1990 to 1992.The overall incident of mortality among buffalo and cow neonates was 7.08 and 11.02 per cent, respectively . The mortality was not influenced by sex and birth weight but age of neonates, parity of dams and season of the year had a significant effect. The mortality was significantly higher during 3rd week, summer and among neonates of 2nd parity dams.

Diarrhoea in neonates of both the species caused higher morbidity, mortality and fatality than pneumonia and pneumo-enteritis. Navel-ill, umbilical hernia and mange caused only morbidity whereas heat stroke proved fatal in one cow neonate.

Haematological values with regards to sex of neonates and parity of dams showed non-significant differences in both of the species. The number of RBCs was significantly less whereas Hb. Concentration, PCV, MCV, MCHC, and TLC were significantly higher at birth in healthy neonates. Significantly low ESR at birth in buffalo neonates was recorded whereas in cow neonates it showed non-significant variation. Rouleaux formation was observed in buffalo neonates. Neutrophils showed significantly higher counts at birth than lymphocytes from 2nd week onward, lymphocytes were more in number than neutrophils and this trend continued up to 4th week of age in neonates under observation.

In diarrhoeic and pneumo-enteric buffalo and cow neonates significantly higher values of RBC and PCV were recorded whereas MCHC were significantly decreased. Leucocytosis mainly due to neutrophilia along with lymphocytopenia was recorded in diarrhoea, pneumonia and pneumo-enteritis in neonates under observation.

Significantly higher morbidity due to diarrhoea, pneumonia and pneumo-enteritis in neonates having intermediate and low concentration of IgG1 was recorded with a relative risk of 3.65 and 5.03 times more in buffalo and 3.21 and 4.28 times more in one neonate. Mortality was three times more in neonates having intermediate and as high as nine times in neonates with low IgG1 concentration as compared to neonates having high IgG1 concentration.

Enteropathogenic E. coli and Salmonella spp. Were isolated from faecal samples of diarrhoeic neonates. The incident of the former was significantly higher in 1st week and of the later in 3rd week of age. Bacterial organisms isolated from nasal dischargers of pneumonic neonates showed highest incident of Pasteurella haemolytica followed by Actinomyces pyogenes, Staphylococci, Streptococci and P. multocida.

Diarrhoeic lesions in neonates of both the species were nearly the same whether caused by enteropathogenic E. coli and Salmonella spp. or with no established aetiology .The carcasses showed moderate to severe emaciation and dehydration. Milk curds in abomasum and mucosal haemorrhages were recorded .Lesions in the duodenum were minimal and less severe than those in the jejunum and ileum which showed focal to diffuse hyperaemia and petechial or linear haemorrhages. The faeces were yellowish-watery mixed either with mucous, blood or fibrinonecrotic material. Hepatomegaly with distended gall bladder were also observed. Histologically, the most severe and most frequent changes were observed in the mucosa, followed by those in the submucosa, muscular and serosal layers of small intestines of diarrhoeic neonates. Sloughing of lining epithelium and villi, congestion on the tips of villi along with stunting and fusion and in severe cases, necrosis of villi were the salient features. Among infiltrating cells, neutrophils were followed by lymphocytes, plasma cells and macrophages in limina propria, periglandular areas and lumen of crypts of Lieberkühn. The submucosa showed dilatation, oedema and congestion. Sections of intestines of buffalo neonates having parasites in their lumen showed sloughing of villi, hyperplasia of crypts of Lieberkühn, massive infiltration of neutrophils and few macrophages in the periglabndular areas. Buffalo and cow neonates died of pneumonia and pneumo-enteritis showed diffusely distributed consolidated areas in the apical, cardiac and intermediate lobes which appeared congested or anaemic and firm in consistency. The overlaying thickened lobes and congested pleura was covered by serofibrinuous in flammatory exudate. The affected lobules yielded frothy, sanguineous or mucinous exudate from bronchi and bronchioles. Histologically, the alveolar capillaries were dilated and studded with blood. Congestion and infiltration with neutrophils was followed by lymphocytes, plasma cells and macrophages in the peribronchiolar connective tissue and within the bronchiolar walls. the alveolar lumens were filled with RBCs , neutrophils, few macrophages and desquamated epithetical cells . Alveolar septa was thickened whereas the interlobular septa was dilated with exudate, inflammatory cells, some newly formed fibroblasts and capillaries.