Heritabilities and genetic correlations of lactational and daily somatic cell score with conformation traits in Polish Holstein cattle

Abstract

The objective of this study was to estimate heritabilities and genetic correlations of lactational and daily somatic cell scores with descriptive and linear type traits in Polish Holstein-Friesian cows. Data were: test-day somatic cell scores and conformation evaluations of 24 599 primiparous cows, daughters of 802 sires. Cows calved from 2006 to 2007. The lactational somatic cell score was calculated as the average of four test-day somatic cell scores at least. The daily somatic cell score was the test-day somatic cell score closest to the date of type evaluation. A multi-trait animal model was used to estimate genetic parameters. (Co)variance components were estimated by a Bayesian algorithm via Gibbs sampling. The heritability of lactational somatic cell score was 0.20 and it was much higher than that of daily somatic cell score (0.13). Heritabilities of type traits were high to moderate for height at rump (0.46), size (0.39), overall conformation score (0.30), two linear rump traits (0.28–0.29) and three linear teat traits (0.26–0.29). The genetic correlation between lactational and daily somatic cell scores was 0.84. In many cases, daily somatic cell score showed higher genetic correlations with type traits than lactational somatic cell score. Descriptive udder and feet and legs scores were genetically correlated negatively with both lactational (–0.22 and –0.20) and daily somatic cell scores (–0.28 and –0.33). Somatic cell traits were genetically correlated positively with rump angle (0.21 and 0.19) and negatively with fore udder height (–0.26 and –0.29), udder depth (–0.23 and –0.17) and central ligament (–0.14 and –0.16). Due to higher heritability, direct selection for lower lactational somatic cell score would be more effective than selection for lower daily somatic cell score. The magnitude of obtained heritabilities and the favourable genetic correlations indicate that the selection utilizing some type traits could improve the resistance to mastitis.

Genetic relationship between lactation persistency and conformation traits in Polish Holstein-Friesian cow population

“…For most linear type traits the average scores were around or slightly above the middle of the scale (5.0) and were consistent with those presented by Ptak et al (2011). Berry et al (2004) obtained lower mean values for traits associated with body size for Irish Holstein-Friesian cows (for example: chest width 4.9, rump angle 4.3), whereas the mean values for most traits associated with udder presented by Berry et al (2004) and Lassen and Mark (2008) were higher than our averages.…”

“…The means of composite traits ranged from 78.10 (SD = 4.52) for overall udder score to 81.95 (SD = 4.16) for size, and showed that the conformation of Polish cows corresponded well with the conformation standard. The means of most composite traits in our study were similar to those obtained by Ptak et al (2011) for the Polish population and Zavadilova and Stipkova (2012) for Czech Holstein cows. The average for stature of Polish HF cows was 143 cm (Table 1), slightly less than the mean obtained by Lassen and Mark (2008) for Danish Holstein cows (144.3 cm).…”

“…Stature is closely related to body weight, which is an important functional trait regulating feed efficiency and energy balance traits in dairy cattle (DeHaas et al 2007). The range of heritabilities for composite traits was similar to the results of the previous study in Polish Holsteins: from 0.11 for overall feet and leg score to 0.39 for size (Ptak et al 2011). Zavadilova and Stipkova (2012) also reported the lowest heritability for feet and legs (0.12), but they estimated the highest heritability not for size as in this paper but for dairy form (0.28).…”

“…Conformation was the first group of nonproduction traits scored and included in the selection indices for dairy cattle populations around the world (Misztal et al 1992;DeHaas et al 2007;Nemcova et al 2011;Ptak et al 2011). The main reason for collecting and using information on type traits in breeding programs is to select more profitable and functional cows.…”

Dry period length in Montbéliarde cows and its association with selected production and functional characteristics

“…It is commonly known that selection for increased milk production is connected with unfavourable reproduction and health disorders. It also causes a decline in functional traits (Vaněk 2004, Vacek et al 2007, Ptak et al 2011. In the own studies, increasing milk yield in standard lactation was accompanied by a significant decrease in dry period length (119, 81, 64 and 60 days).…”