Genotype by environment interaction for activity based estrus traits in Danish Holstein

• The objective of this study was to investigate whether genotype by environment interaction (G×E) exists for female fertility traits with regards to production level. The fertility traits considered were: (1) interval from calving to first high activity (CFHA); (2) duration of first estrus (DFE); and (3) strength of first estrus (SFE). Estrus traits were derived from electronic activity tags for 11,522 first parity cows housed in 125 herds. Data were analyzed using random regression animal model (RRM) by regressing the phenotypic performance on the average herd energy corrected milk yield as an environmental gradient. For validation of the random regression model results, data were further analyzed using a bivariate model (BM) considering the same trait in high and low production environments as different trait. The heritability estimate for CFHA decreased from 0.25 to 0.10 with increasing production level. For DFE, heritability estimate obtained by BM for the low producing herds were more than twice the estimates for high producing herds, this trend was however not detected by the RRM results. For SFE, heritability estimates decreased from 0.12 in the lowest environment to the minimum estimate of 0.03 before increasing gradually to 0.13 in the highest environmental scale. The genetic correlation of the same trait in low and high production environments was around 0.74 for CFHA, 0.22 for SFE and 1.00 for DFE using RRM with similar estimates using BM. These results indicated no evidence of G×E interaction effect on CFHA, DFE, while there was strong G×E for SFE, which indicate that G×E interaction should be included in the evaluation of this trait.

Ämnesord

LANTBRUKSVETENSKAPER  -- Bioteknologi med applikationer på växter och djur -- Genetik och förädling inom lantbruksvetenskap (hsv//swe)

AGRICULTURAL SCIENCES  -- Agricultural Biotechnology -- Genetics and Breeding in Agricultural Sciences (hsv//eng)

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