Characteristics, Curve and Persistency of Lactation in Gir Cows

Lactation milk yield in dairy bovines is closely related with peak yield, persistency and lactation length. Therefore, characteristics, curve and persistency of lactation were studied in Gir cows. A total of 2,24,748 morning and evening milk production records of 300 lactations of 1-6 parity Gir cows present at Cattle Breeding Farm, JAU, Junagadh, Gujarat over a period of 31 years (1986-2016) were used for this study. Overall lactation length (LL), total lactation milk yield (TLMY) and standard lactation milk yield (SLMY) of the Gir cows averaged 371.59 ± 5.42 days, 2674.21 ± 48.79 lit and 2380.79 ± 37.68 lit, respectively. Overall daily peak yield (DPY) was 13.25 ± 0.17 lit/day, attained at 48.47 ± 2.40 days postpartum. Overall weekly peak yield (WPY) and weeks to attain WPY averaged 82.08 ± 1.11 lit/week and 6.54 ± 0.31 weeks, respectively. Weekly milk yield could be predicted using linear function [(y ̂ =79.5139+(-1.1002 × X)] and logarithmic function [(y ̂ =1.9378 × (-0.00965) ^X)] with an accuracy of 86 to 95%, while monthly milk yield could be predicted using linear function [(y ̂ =348.52+(-20.26 × X)] and logarithmic function [(y ̂ =2.588 × (-0.042) ^X)] with comparatively higher R2 value of 94.01 to 98.05%. Overall persistency, in terms of weekly and monthly milk yield was estimated to be 96.82 ± 0.13% and 88.77 ± 0.37%, respectively.