134 Comparison of the effect of artificial insemination and in vitro embryo production on gestation length, calf birthweight, and calving difficulty
A. D. Crowe A B , M. B. Rabaglino B , J. M. Sanchez B C , S. G. Moore A , M. McDonald B , P. Lonergan B and S. T. Butler AA Teagasc, Animal and Grassland Research and Innovation Centre, Moorepark, Fermoy, Cork, Ireland
B School of Agriculture and Food Science, University College Dublin, Dublin, Ireland
C Instituto Nacional de Investigación y Tecnología Agrária y Alimentaria, Madrid, Spain
Reproduction, Fertility and Development 35(2) 195-195 https://doi.org/10.1071/RDv35n2Ab134
Published: 5 December 2022
© 2023 The Author(s) (or their employer(s)). Published by CSIRO Publishing on behalf of the IETS
The aim of this study was to determine the effect of embryo origin (artificial insemination [AI] vs embryo transfer [ET]), calf breed, and calf sex on gestation length (GL), birthweight (BW), and calving difficulty (CD) score. Lactating dairy cows were randomly assigned to be bred by timed AI (n = 60; frozen-thawed semen) or timed ET with fresh (n = 121) or frozen (n = 92) in vitro-produced (IVP) embryos. The IVP embryos were either dairy (Holstein Friesian [FR], n = 81 or Jersey [JE], n = 38) or beef breed (Angus [AA], n = 94). Data were subsequently obtained from 273 calves who were derived from these breeding events. For all calves, weight was recorded immediately after birth and calving difficulty was scored on a scale of 1 to 4: 1 = unassisted calving (n = 174), 2 = minor assistance (n = 52), 3 = considerable difficulty (n = 45), or 4 = veterinary assistance/Caesarean (n = 3). The effects of the independent variables (origin, breed, and sex) on GL, BW, and CD score, and the association between these dependent variables was determined through a multiple regression model. There was a positive correlation between GL and BW (R2 = 0.11; P < 0.0001) and between and BW and CD score (R2 = 0.3; P < 0.0001). Overall, origin of the calf affected GL (AI: 276.7 ± 4.2; ET-Fresh: 280.9 ± 4.9; ET-Frozen: 280.4 ± 5.0 days; P = 0.012) and BW (AI: 34.6 kg ± 5.6 kg; ET-Fresh: 40.8 kg ± 9.1 kg; ET-Frozen 39.8 kg ± 7.7 kg; P < 0.0001). Breed affected BW, GL, and CD (P < 0.01, Table 1). Among calves born from ET, AA calves were heavier than FR or JE (P < 0.0001). Considering FR calves only, calves born from ET (fresh or frozen) were heavier than those born from AI (P < 0.01). Overall, male calves were heavier than females (40.8 ± 8.2 kg vs 37.2 ± 8.0 kg; P < 0.02). There were no interactions between any of the variables. In conclusion, calves originating from IVP/ET were heavier at birth, had longer GL, and had a greater incidence of CD than calves born from AI.
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This research was supported by the Department of Agriculture, Food and The Marine (Grant 2021R665) and Science Foundation Ireland (Grant 16/RC/3835; VistaMilk).
