Identification and evaluation of new related groups in the Red-and-White breed

The objective of the study is to identify and evaluate new related groups in the RedandWhite dairy cattle breed based on their breeding value and a comprehensive selection index. Objectives: to evaluate bulls from established genealogical lines and branches for key economically valuable traits (milk yield, fat and protein content in milk, fat and protein yield (kg), productive longevity of daughters, and fertility) using a herd of daughter cows born between 2010 and 2018 using a comprehensive index that takes into account productivity, fertility, and productive longevity traits, developed using the BLUP AM mixed linear model. The object of the study was a population of live RedandWhite cows (n = 5,717), and their data on economically valuable traits were accessed from the SELEX. Dairy Cattle database. Thirtysix related groups were identified within the existing Holstein lines, including RedandWhite and Simmental bulls. Initially, bulls were assigned to related groups if they produced a sufficient number of daughters for line evaluation (at least 21 animals) and had semen reserves from these bulls or their heirs. Then, an index assessment of the overall breeding value was conducted using a set of traits for the identified related groups, based on the breeding value of the cows within these groups. The breeding value of cows in the identified related groups was assessed using the BLUP method. The development of the complex selection index was based on a method of simultaneous selection for several traits—productivity, fertility, and longevity. When assessing the economic efficiency of breeding new related groups, the greatest economic benefit was achieved by cows from the Huloka 679855609 related group, with an average improvement of 45,303–171,471 rubles. A positive economic effect was achieved in 16 of the 36 identified related groups. Fortyfour percent of the identified related groups have the potential to increase the duration of economic use: in the Taylor 134375085, Kompas 9080, and Uspekh 20546 groups, productive longevity can be expected to be on average one lactation longer. A positive comprehensive selection index for assessing the economic efficiency of breeding his daughters can be considered the target standard for sires from the newly identified related groups. If the subindices for milk yield, fertility, and longevity that comprise the selection index also have positive values, then such a bull is recognized as an improver in all three traits. The minimum values of the complex selection index for a breeding bull are no less than 48,676 rubles.