Factor analysis for udder and teat type traits in Sahiwal and Karan Fries cows

Abstract

Selecting female cows for productivity based on udder and teat traits is essential in field due to lack of available records. The objective of the present study was to reduce the dimensionality of the 17 udder and teat traits and to analyse their impact on milk productivity. The data on 256 cattle comprising 133 Sahiwal and 123 Karan Fries cows were used in this study over the years 2017-2019 from Livestock Research Centre (LRC) of ICAR-National Dairy Research Institute, Karnal. The 17 udder and teat traits were fore udder attachment (FUA), rear udder width (RUW), rear udder height (RUH), udder balance (UB), udder depth (UD), udder length (UL), udder width (UW), udder circumference (UC), central ligament/udder cleft (CL), teat circumference (TC), fore teat length (FTL), rear teat length (RTL), distance between fore and rear teat (DFR), distance between left and right teat (DLR), shortest distance from floor to fore teat (SDFT), shortest distance from floor to rear teat (SDRT) and teat diameter (TD). In the factor analysis, first five latent factors accounted for 62.22% of total variance in udder and teat measurements for Sahiwal cows and 65.67% in Karan Fries (KF) cows, respectively. In Sahiwal cows F1 represented better udder support and wideness (wide udders, udders were supported by strong suspensory ligament), whereas in KF cows, first factor reflected better udder dimension and distance between teats (longer length, width of udder and well placed teats). Factor analysis could reduce the multicollinearity of the data. It can be concluded that inclusion of udder and teat measurements in selection index can be a reliable criteria for selecting cows for higher milk yield.