Genetic analysis of atypical progesterone profiles in Holstein-Friesian cows from experimental research herds

Abstract

The objective of this study was to quantify the genetic variation in normal and atypical progesterone profiles and investigate if this information could be useful in an improved genetic evaluation for fertility for dairy cows. The phenotypes derived from normal profiles included cycle length traits, including commencement of luteal activity (C-LA), interluteal interval, luteal phase length. and interovulatory interval. In total, 44,977 progesterone test-day records were available from 1,612 lactations on 1,122 primiparous and multiparous Holstein-Friesian cows from Ireland, the Netherlands, Sweden, and the United Kingdom. The atypical progesterone profiles studied were delayed cyclicity, prolonged luteal phase, and cessation of cyclicity. Variance components for the atypical progesterone profiles were estimated using a sire linear mixed model, whereas an animal linear mixed model was used to estimate variance components for the cycle length traits. Heritability was moderate for delayed cyclicity (0.24 ± 0.05) and C-LA (0.18 ± 0.04) but low for prolonged luteal phase (0.02 ± 0.04), luteal phase length (0.08 ± 0.05), interluteal interval (0.08 ± 0.14), and interovulatory interval (0.03 ± 0.04). No genetic variation was detected for cessation of cyclicity. Commencement of luteal activity, luteal phase length, and interovulatory interval were moderately to strongly genetically correlated with days from calving to first service (0.35 ± 0.12, 0.25 ± 0.14, and 0.76 ± 0.24, respectively). Delayed cyclicity and C-LA are traits that can be important in both genetic evaluations and management of fertility to detect (earlier) cows at risk of compromised fertility. Delayed cyclicity and C-LA were both strongly genetically correlated with milk yield in early lactation (0.57 ± 0.14 and 0.45 ± 0.09, respectively), which may imply deterioration in these traits with selection for greater milk yield without cognizance of other traits.

Estimating genetic parameters for fertility in dairy cows from in-line milk progesterone profiles

“…Veerkamp et al (2000) reported higher correlations of C-LA with MY (0.51), PY (0.48), and FY (0.65) for 305-d yield records, whereas Royal et al (2002a) found an estimate (0.36) for lnC-LA with predicted milk yield on d 56 and Nyman et al (2014) found a genetic correlation of 0.45 ± 0.09 for lnC-LA with ECM during the first 60 DIM. Furthermore, the negative genetic correlations between PLA and milk production traits suggest an unfavorable influence of genetic merit for yield on genetic merit for PLA.…”

“…Fitting a genetic regression of daughter lnC-LA on sire PTA for CInt, Royal et al (2002b) inferred a genetic correlation of 0.36 between lnC-LA and CInt, whereas Berry et al (2012) reported an estimate of 0.87 ± 0.33 from an animal model. Similarly, positive genetic correlations between lnC-LA and CFS (0.37 ± 0.34 and 0.35 ± 0.12) have been reported (Berry et al, 2012;Nyman et al, 2014).…”

“…The genetic correlation of lnC-LA with CFS (0.37 ± 0.21) and CInt (0.26 ± 0.33) imply that decreasing lnC-LA by 1 genetic standard deviation will decrease CFS by 4.1 d and CInt by 3.7 d. Some studies have examined the correlations between endocrine and classical fertility traits. Nyman et al (2014) found a correlation of 0.54 ± 0.27 between lnC-LA and CInt. Fitting a genetic regression of daughter lnC-LA on sire PTA for CInt, Royal et al (2002b) inferred a genetic correlation of 0.36 between lnC-LA and CInt, whereas Berry et al (2012) reported an estimate of 0.87 ± 0.33 from an animal model.…”

Phenotypic and genetic parameters for selected production and reproduction traits of Mpwapwa cattle in low-input production systems

“…On the other hand, heifers and cows that are well fed are likely to undergo normal cyclic behaviour and therefore to improve both AFC and CI. Studies in temperate countries have suggested the possibility of selection for reduced CI by using other genetically correlated traits such as body condition score and milk progesterone (Dal Zotto et al, 2007;Nyman et al, 2014). A decrease in AFC and CI would reduce the cost for herd replacement and maximize the longevity and the productive life of a cow.…”

Genome-wide association study of normal and atypical progesterone profiles in Holstein-Friesian dairy cows

“…Endocrine fertility traits, such as progesterone (P4) profiles, might be more useful because they have higher heritabilities and more closely reflect the biology of the cow compared with classical fertility traits. Deviations from a normal estrous cycle, termed atypical P4 profiles, have been associated with compromised fertility (Bulman and Wood, 1980;Royal et al, 2002), and have an antagonistic relationship with milk yield in early lactation (Nyman et al, 2014). Heritabilities of delayed cyclicity and commencement of luteal activity (C-LA) determined by P4 profiles are generally higher.…”