Genetic Evaluation of Fertility Using Direct and Correlated Traits

Abstract

Poor fertility has become a major reason for involuntary culling of dairy cows in the United Kingdom. Calving interval (CI) and body condition score (BCS) are recorded, heritable, genetically correlated with each other, and could be used to extend the scope of dairy indices to include fertility traits. The use of U.K. insemination information for the evaluation of fertility has not been examined previously. Fertility and correlated traits were examined using nationally recorded milk (MILK = daily milk yield at test nearest d 110), BSC, and fertility traits (CI and the insemination traits of nonreturn rate after 56 d, NR56; days to first service, DFS; and number of inseminations per conception, INS). Genetic parameters for the traits were estimated simultaneously with a multitrait sire maternal grandsire (MGS) model and a multitrait BLUP sire MGS model was used to predict sire predicted transmitting abilities for each trait. The relationship between the fertility traits and other predicted transmitting abilities calculated in the United Kingdom was then examined. Heritabilities for the fertility traits were CI = 0.033 +/- 0.01, DFS = 0.037 +/- 0.01, NR56 = 0.018 +/- 0.001, and INS = 0.020 +/- 0.001, with a genetic correlation of 0.671 +/- 0.063 between CI and DFS and -0.939 +/- 0.031 between NR56 and INS. There was an unfavorable genetic correlation between the fertility traits and milk yield and BCS. Predicted transmitting abilities produced are similar in size and range to those produced in other studies and genetic trends are as expected. Results to date are encouraging and suggest that the planned program of work will lead to a fertility index that, when used by breeding companies, will lead to improvements in national dairy cow fertility.

Genome-wide associations for fertility traits in Holstein–Friesian dairy cows using data from experimental research herds in four European countries

“…The low heritability of the traditional fertility traits in the present study corroborates the many previous studies on genetic parameters for traditional fertility measures (Pryce and Veerkamp, 2001;Berry et al, 2003;Wall et al, 2003). The heritability estimates of CFH and CFS, however, are slightly larger than that generally observed from field data, which may be attributable to an expected greater accuracy of recording in experimental herds.…”

“…Genetic correlations among the traditional fertility variables were generally similar to those estimated on primiparae in larger datasets (Wall et al, 2003). Nonetheless, the genetic correlations between the traditional fertility traits and CLA were different from those reported elsewhere, albeit the standard errors in the present study and in most of the other studies were large, attributable to a combination of low heritability of the fertility traits and the relatively small datasets.…”

“…influenced by a large or small number of genes). Large population sizes for genome-wide association analysis are required for lower heritability traits such as traditional measures of fertility (Pryce and Veerkamp, 2001;Berry et al, 2003;Wall et al, 2003); this can be somewhat overcome by using fertility-estimated breeding values on genotyped sires as the phenotype under investigation; nonetheless, phenotypes on a large number of cows are still required to generate accurate sire-estimated breeding values. The low heritability of fertility traits can be due to a multitude of factors including: (1) the trait is truly under poor additive genetic control relative to non-additive and non-genetic factors; (2) the statistical model used to estimate the variance components is too simplistic relative to reality; (3) recording errors adding to random noise; and (4) preferential treatment that cannot be fully accounted for in the statistical model.…”

“…However, the low heritability of many traditional fertility traits (Pryce and Veerkamp, 2001;Berry et al, 2003;Wall et al, 2003), coupled with the long time period necessary to acquire some of the phenotypes (e.g. calving interval, CI), imply that selection -E-mail: donagh.berry@teagasc.ie for these traits using traditional methods is more difficult than selection, for example, for milk yield traits.…”

Association between age at first calving, year and season of first calving and milk production in Holstein cows

“…Several studies have reported a longer calving interval in recent years than before, including studies in Canada (Murray, 2003), Spain (Gonzá lez-Recio et al, 2004), the Netherlands (Nederlands Rundvee Syndicaat (NRS), 2005) and the United Kingdom (Wall et al, 2003). According to Hare et al (2006a), the increase is about 1 day per year for Holsteins.…”