Effect of inclusion or non-inclusion of short lactations and cow and/or dam genetic group on genetic evaluation of Girolando dairy cattle

Abstract

ABSTRACT. The objective of this study was to evaluate the effects of inclusion or non-inclusion of short lactations and cow (CGG) and/or dam (DGG) genetic group on the genetic evaluation of 305-day milk yield (MY305), age at first calving (AFC), and first calving interval (FCI) of Girolando cows. Covariance components were estimated by the restricted maximum likelihood method in an animal model of single trait analyses. The heritability estimates for MY305, AFC, and FCI ranged from 0.23 to 0.29, 0.40 to 0.44, and 0.13 to 0.14, respectively, when short lactations were not included, and from 0.23 to 0.28, 0.39 to 0.43, and 0.13 to 0.14, respectively, when short lactations were included. The inclusion of short lactations caused little variation in the variance components and heritability estimates of traits, but their non-inclusion resulted in the re-ranking of animals. Models with CGG or DGG fixed effects had higher heritability estimates for all traits compared with models that consider these two effects simultaneously. We recommend using the model with fixed effects of CGG and inclusion of short lactations for the genetic evaluation of Girolando cattle.

Abnormal Lactation Lengths and its Consequences on Performance of Crossbred Cattle

“…Among Sahiwal cattle, only 32.48% of total lactation records fell in the range of 251-350 days of lactation length, while more than three-fourth (76%) of total observations failed to reach the standard level of 305 milking days (Narwaria et al 2015). Vaccaro et al (1999) and Canaza -Cayo et al (2016) reported fewer incidences of short lactations upto 100 days as 3.8-4% and 2.5%, respectively whereas Facó et al (2009) reported a higher incidence of shorter than 120 days as 13.6% of lactations among dairy cattle.…”