Vol. 9, Special Issue 1, Part I (2025)

The research was carried out on crossbred Jersey cattle housed in a modified loose housing system at the livestock farm complex, VCRI, Orathanadu, Tamil Nadu during 2019-2020. For each season, twenty-four whole blood samples were collected from 12 crossbred dairy cattle in the morning at rest (9.00 a.m.) and in the evening following exposure to sunlight (2.00 p.m.) for hematological analysis. RBC count (10⁶/µl) at rest in the morning and evening after exposure to sunlight during South West Monsoon (SWM) were 5.84±0.17 and 5.48±0.15; during North East Monsoon (NEM) were 6.19±0.14 and 5.87±0.04; during winter were 6.34±0.17 and 6.10±0.16 and during summer were 5.82±0.11 and 5.40±0.14, respectively. WBC count (10³/µl) recorded at rest in the morning, and evening after exposure to sunlight during SWM were 7.10±0.31 and 7.69±0.39; during NEM were 6.84±0.33 and 7.23±0.14; during winter were 6.80±0.47 and 7.17±0.48 and during summer were 7.56±0.29 and 8.41±0.27, respectively. Hb (g/dL) values recorded at rest in the morning, and evening after exposure to sunlight during SWM were 8.69±0.23 and 8.06±0.22; during NEM were 9.12±0.11 and 8.44±0.06; during winter were 9.30±0.20 and 8.81±13; during summer were 8.64±0.16 and 7.83±0.15, respectively. The Mean ± SE of PCV (%) recorded for the crossbred dairy cattle at rest in the morning, and after exposure to sunlight in the evening during SWM were 24.57±0.56 and 22.69±0.60; during NEM were 25.06±0.35 and 23.35±0.17; during winter were 25.82±0.53 and 24.57±0.48; during summer were 23.87±0.47 and 21.75±0.39, respectively. Platelet count (10³/µl) of crossbred dairy cattle at rest in the morning, and evening after exposure to sunlight during SWM were 274.79±21.34 and 235.79±20.47; during NEM were 291.29±4.85 and 264.36±2.94; during winter were 296.07±9.17 and 268.29±7.55; during summer were 270.43±5.84 and 222.00±3.92, respectively. RBC count and hemoglobin values revealed that there was no significant difference between seasons at rest in the morning, whereas highly significant difference (p<0.01) was observed in the evening after exposure to sunlight between winter and summer seasons for RBC count and hemoglobin values, and between winter and SWM for hemoglobin values alone. In terms of PCV values, a significant difference was found between the winter and summer seasons in the morning at rest, whereas a highly significant difference was found between the winter and summer seasons in the evening after exposure to sunlight. Except for the WBC count during NEM, all tests of significance for diurnal change of RBC count, WBC count, Hb, PCV, and PLT count between morning and evening for four seasons were highly significant (p<0.01). According to the findings, it was determined that hematological values during NEM and winter seasons were optimum for enhancing productivity in crossbred Jersey cattle.