​Enhancement of Production Performance of Tharparkar Cattle using Lactation Persistency as A Selection Tool

Abstract

Background: Lactation persistency of cattle is the ability to maintain constant milk production after the peak milk yield. This work was conducted using a total of 372 daily milk yield records of all parities of 190 Tharparkar cattle sired by 38 bulls from 1990 to 2019 (29 years), collected from Animal Genetics and Breeding Division, maintained in Livestock Research centre of NDRI, Karnal. Methods: The lactation persistency was estimated using Mahadevan’s method (1951) based on the ratio of milk production in first 28 weeks to milk production in 10 weeks. Standard error as percentage of mean was used to test the efficiency of persistency indices. To study the effect of non-genetic factors Least-squares analysis was carried out by Harvey (1990) model. Result: The least squares mean of total milk yield (TMY), lactation length (LL), peak yield (PY), days to attain peak yield (DAPY) and lactation persistency (LP) were 1633.40±45.79Kg, 272.55±4.64 days, 10.83±0.17kg, 41.48±2.34 days and 1.27±0.02 respectively. First calvers had highest LL, DAPY and persistency. Rainy calvers had more TMY, LL, DAPY and LP and winter calvers were the low performers. Correlation of persistency with TMY, LL and DAPY were highly significant and positive. There was negative correlation with PY and LP. The estimated heritability for TMY, LL and PY was 0.16±0.34, 0.49±0.38 and 0.84±0.41 respectively. The heritability estimate of lactation persistency was very low with high standard error which revealed the significance of environmental effect in persistency.