JOSHUA TERSUE ADEKE2023-09-212023-09-212018-10-26https://teras.ng/api/asset/document/c4af68db-b16c-40f2-a287-c684d464db01https://teras.ng/catalog-item/48597fd6-ddb1-4b0a-945d-013a173c4b22http://dspace.teras-network.net:4000/handle/123456789/13533This study determined the reproductive endocrine and clinico-pathological changes associated with Escherchia coli (E. coli ) infection in layer chickens. A total of 20 laying chickens (20 weeks old) were acquired and assigned, at random, into two groups (infected and control) of 10 layers each. Each of the birds in the infected group was challenged with 0.5 ml of bacterial aliquot containing 109 colony forming units (CFU) of the bacteria, administered intratracheally. Three (3) ml of blood were collected from each bird in both groups and used for haematological and biochemical analyses. E. coli infection in the layers caused reduction in feed and water consumption, watery yellowish faeces and weakness by day 3 post infection (pi) and also decreased mean oestrogen profile from day 6 (347 ± 2.55 pg/ml) reached the lowest value (332.6 ± 5.41 pg/ml) on day 28 pi that differed significantly (p < 0.05) from the corresponding value in the control group. The mean plasma progesterone profile in the infected group started from day 4 pi and reached the lowest significant (p<0.05) value (94.8 ± 1.98 pg/ml) on day 28 pi, against the control group. The mean plasma calcium concentration decreased from day 6 to reach a lowest level (1.61 ± 0.11 mmol/L) on day 14 pi, which was significantly different (p < 0.05) from that in the control group. The mean plasma phosphate concentration increased from day 6 to a significantly (p < 0.05) higher level (1.64 ± 0.12 mmol/L) on day 14. The mean parathormone profile increased from day 6 (24.10 ± 0.56 pg/ml) to a significantly (p < 0.05) higher level on day 21 (31.04 ± 0.80 pg/ml). The mean plasma aspartate aminotransferase (AST) activity in the infected group progressively increased from day 6 pi to reach a significantly higher (p < 0.05) value (66.4 ± 0.93 IU/L) on day 28 pi while the mean plasma alanine aminotransferase (ALT) activity progressively increased in the infected group beginning from day 6 pi to attain the highest significant (p < 0.05) value (74.4 ± 2.11 IU/L) on day 21 pi compared to the control group. The mean plasma total protein concentration in the infected group decreased from day 4 piResearch Theses