Direct and maternal genetic relationships between calving ease, gestation length, milk production, fertility, type, and lifespan of Holstein-Friesian primiparous cows

Abstract

As the emphasis in cattle breeding is shifting from traits that increase income toward traits that reduce costs, national breeding indices are expanding to include functional traits such as calving ease (CE). However, one issue is the lack of knowledge of genetic relationships between CE and other dairy traits. The same can be said about gestation length (GL), a potential novel selection trait with considerable heritabilities and possible genetic relationships with the calving process. This study aimed to estimate the genetic relationships between CE, GL, and other dairy traits of interest using a national data set of 31,053 primiparous cow performance records, as well as to separate direct and maternal genetic effects. Chosen dairy traits included fertility (calving interval, days to first service, nonreturn rate after 56 d, number of inseminations per conception), milk production (milk yield at d 110 in milk, accumulated 305-d milk yield, accumulated 305-d fat yield, accumulated 305-d protein yield), type (udder depth, chest width, rump width, rump angle, mammary composition, stature, body depth), and lifespan traits (functional days of productive life). To allow the separation of direct and maternal genetic effects, a random sire of the calf effect was included in the multi-trait linear trivariate sire models fitted using ASReml. Significant results showed that easily born individuals were genetically prone to high milk yield and reduced fertility in first lactation. Difficult calving primiparous cows were likely associated with being high-producing, wide and deep animals, with a reduced ability to subsequently conceive. Individuals that were born relatively early were associated with good genetic merit for milk production. Finally, individuals carrying their offspring longer were genetically associated with being wide and large animals that were themselves born relatively early. The study shows that it is feasible and valuable to separate direct and maternal effects when estimating genetic correlations between calving and other dairy traits. Furthermore, gestation length is best used as an indicator trait for lowly heritable calving traits, rather than as a novel selection trait. As estimated direct and maternal genetic correlations differ, we can conclude that genetic relationships between CE, GL, and traits of interest are present, but caution is required if these traits are implemented in national breeding indices.

Genotype by environment interaction for livability of dairy calves from first parity cows

“…To enable comparison of our results to those of other studies using a threshold model, the transformed heritabilities on the underlying scale (h 2 transf us ) were computed from the heritability (h 2 ) estimates computed for each herd level using the model described above as h 2 transf us ¼ h 2 pð1ÀpÞ z 2 where p is average incidence of livability at the herd level and z is the ordinate of the standard normal density function corresponding to p (Dempster and Lerner, 1950 (Wiggans et al, 2003),σ sire;mgs is the estimated covariance between sire and maternal effects. A derivation of this formula is provided in the Appendix of Eaglen et al (2013). When computing the maternal heritability, we ignored the termσ sire;mgs to compute the q whereσ mgs 1 ;mgs 2 is the estimated maternal grandsire covariance between environments 1 and 2, andσ 2 mgs 1 is the estimated maternal grandsire variance for environment 1.…”

Heifer fertility and carry over consequences for life time production in dairy and beef cattle

“…Selection of the sire can be important. Many producers will take calving ease into consideration (Eaglen et al, 2013). However, bull fertility is also variable, with a study of Angus beef heifers reporting variations in pregnancy rates between sires of 65% to 100% within a breeding season (Bormann et al, 2006).…”

“…The major cause of dystocia is disproportion between the fetus and dam. This can be influenced by choice of sire (Eaglen et al, 2013) but the dam's relative maturity and pelvic width are also critical. Inadequate skeletal maturity can be a problem if the AFC is < 24 months (Hansen, 2004).…”

Genetic parameters of calving ease in dairy cattle using threshold and linear models

“…Similar CE distribution has been reported by Eaglen and Bijma (2009). However, in other studies, the score with the highest frequency was score 1 (Wiggans et al 2003;Eaglen et al 2013). Differences between authors in CE classes' definition can contribute to those discrepancies.…”