Estimates of heritability for somatic cell count, test-day milk yield and some udder-teat characteristics in Saudi dairy goats using random regression animal model

Abstract

The objective of the present study was to estimate heritability and permanent environmental effect for test-day Somatic Cell Count and Somatic Cell Score (SCC & SCS), Test Day Milk yield (TDM), some Udder-Teat Characteristics(UTC) in Aradi Saudi goat using random regression animal model. Estimates of SCC and TDM were examine every 15 days after parturition across the first four parities. Udder-teat characteristics involved in the present study were Udder Depth Side View (UDSV),Teat Placement Rear View (TPRV) and Teat Size (TS). The current data involved, 5642, 4712, 3847 and 3104 test-day records in the first 4 parities, respectively recorded between 2010 and 2015. Polynomial random regression of the third order seemed adequate to explain variation in somatic cell count, test-day milk yield and udder-teat traits. Estimates of heritability for all studied traits were compute using random regression animal model across different stage of lactation within each parity. Overall estimate of heritability for somatic cell score was 0.24+0.09 and ranging from 0.16 during early stage of lactation of the first parity to 0.31 at the third parity during end of lactation. Overall estimates of permanent environmental effect for somatic cell score was 0.46+0.12 and raging from 0.31+0.11 to 0.64+0.14 across the first four parities. Heritability of test-day milk yield were ranged from 0.12 during early stages of the 1st lactation to 0.42 during mid-lactation of the 4th parity. Overall estimates of heritability for test day milk yield were 0.21+ 0.09, 0.23+0.11, 0.27+0.11, and 0.33+0.09 during the first four parity, respectively. Overall estimates of heritability for udder-teat traits were 0.46, 0.52, and 0.61 for UDSV, TPSV, and TS, respectively. The current results indicate that, improvement milk production and reduce the level of somatic cell count are possible at some points of lactation stages.