Reproduction traits, growth traits and age at first calving in Holstein heifers

Abstract

The objective of this study was to verify the reproductive efficiency expressed by traits, interval from first to second calving (IDP), number of services per conception to the first calving (NSC1), number of services per conception for the second calving (NSC2), service period from the first to the second calving (PS) and gestation lenght (PG) of Holstein heifers. Data from 377 heifers from two herds, one in Santa Cruz do Rio Pardo, São Paulo and another in Rolândia, Paraná were analysed. The statistical model to analyze IDP, NSC1, NSC2, PS and PG included the fixed effect of Contemporary Group (CG). To analyze PG, it was also considered the effect of calf sex. To evaluate the growth performance and age at first calving (AFC), data from 360 Holstein heifers belonging to property in Rolândia were analysed. The model included the fixed effects of contemporary groups (CG) and average daily gain from birth to 15 months (ADG). A similar model was used to analyze weigth at 458 dias (W458) and ADG, therefore considering only CG. The overall means of IDP, NSC1, NSC2, PS and PG, were 14.96 ± 3.94 months; 1.35 ± 0.71 services, 2.86 ± 2.37 services, 178.83 ± 118.73 days; 276.67± 5.65 days, respectively. Correlations were observed between the traits IDP and NSC2 of 72% (P<0.0001), between IDP and PS of 98% (P<0.0001) and between NCS2 and PS of 72% (P<0.0001). The gestation length of males and females showed estimated average of 277.53 ± 0.46 days and 276.33 ± 0.40 days, respectively, and the calf sex was source of variation on PG (P<0.05). Average daily gain was a significant source of variation on AFC and CG affected all traits studied. The estimated average for AFC was 24.18 ± 1.59 months, for W458 was 362.33 ± 36.24 kg and ADG was 0.704 ± 0.08 kg.

Keywords

• Average daily gain; Contemporary group; Days open; Gestation length; Calving interval; Services per conception