Genetic parameters of longevity for improving profitability of beef cattle1

Abstract

The objective of this study was to estimate genetic parameters for longevity and assess the suitability of using these selection criteria to improve the genetic merit of the beef cattle population of the Czech Republic. The performance record database, which contains records of 363,000 beef cattle animals of 19 breeds and their crosses, was used. The populations of Charolais and Aberdeen Angus were large enough that the genetic parameter estimations and all analyses were done for these breeds separately. Two similar approaches of longevity definition based on probabilities were considered as follows: productive longevity (PL), which is the number of calvings at target ages of 78, 90, 150, and 160 mo, and longevity (L), which is based on the probabilities of cow reappearance in the next parity. A multibreed single-trait animal model for L and a multitrait animal model for combinations of 78/150 and 90/160 mo for PL were used. Specific combinations of months were established based on the analysis and represented the critical culling rates in the studied population. The high genetic correlations (0.88-0.95) of the combination 90/160 suggested that the PL at 160 mo of age can be predicted on the basis of the value at 90 mo, which will make earlier selection possible. Combination 78/150 is less efficient in the Czech population of beef cattle due to the lower correlations (0.79-0.93) between traits. The estimated heritabilities were low for both traits (below 0.14), but the additive genetic variance was sufficient for identifying animals with high genetic merit.

Using Random Regression Models to Genetically Evaluate Functional Longevity Traits in North American Angus Cattle

“…In general, most peaks of heritability observed for the different longevity definitions analyzed in our study occurred between 4 to 7 years, which indicates that performing selection within this interval can help to accelerate the genetic gain for longevity. This is in agreement with Brzáková et al [ 11 ], who reported that the highest heritabilities were estimated at 6.5 years. On the other hand, the highest heritability reported by Jamrozik et al [ 13 ] was estimated at 2 years.…”

“…Heritabilities. Genetic analysis of longevity (or longevity-related traits, such as stayability and survival) are becoming popular in livestock breeding research [ 11 , 13 , 53 ]. However, to our best knowledge, there are no studies evaluating the impact of different culling reasons in the estimation of variance components and genetic parameters for longevity.…”

“…Brzáková et al [ 11 ] compared the use of two longevity definitions (i.e., probability of cow reappearance in the next parity, and the number of calvings at ages of 6.5, 7.5, 12.5, and 13.3 years) for the genetic evaluation of a beef cattle population in the Czech Republic, using single- and multiple-trait linear models. Despite the fact that the statistical models and the longevity definitions used in their study are not conceptually the same as in our study, the authors reported heritability estimates close to the ones found in our study when considering the group combining all culling reasons under the FLa definition (heritabilities ranging from 0.09 to 0.13).…”

“…For instance, Jamrozik et al [ 13 ] reported genetic correlations ranging from 0.74 to 0.99 between ages 3 to 8 years-old. Brzáková et al [ 11 ] found that productive longevity measured at 7.5 years-old is a good indicator of longevity measured at 13.3 years-old (genetic correlations reported by the authors were above 0.84). In addition, Venot [ 62 ] reported high genetic correlations (0.95 for Charolais and 0.92 for Aubrac) for number of calvings estimated between 6.5 and 12.5 years-old, while evaluating length of productive life in beef cows.…”

“…Therefore, several other definitions of longevity have been proposed over time. For instance, Brzáková et al [ 11 ] recently defined longevity as the period of time from the first to the last calving, while Ramos et al [ 12 ] defined longevity based on the number of calvings until a certain age. In addition, stayability to consecutive calvings [ 13 ] or the probability that a cow remained in the herd until a specific age, given it calved once [ 14 ] have also been proposed as indicators of cow longevity.…”