Is there sire variation in seasonal liveweight gain of rising-yearling red deer?

Red deer exhibit the greatest seasonal control of nutritional physiology of farmed ruminants in New Zealand, highlighted by seasonal inappetence during winter, present in all sex and age classes. Four years of data from 2048 DNA-pedigreed mixed-sex progeny of 112 sires and 1069 dams from a red deer breeding stud were interrogated to investigate the hypothesis of sire variation in growth across seasons in rising yearlings. Analysis used 17145 live weights from progeny with ≥ 4 live weights to a minimum of 300 days of age. Estimates of the weights of all animals at the same age were calculated by fittinga restricted maximum likelihood model to adjust for multiple variables and create sire best linear unbiased predictions of rising-yearling growth. Liveweight gain was examined at 11 key seasonal ages. While overall post-weaning variation in liveweight gain was low (CV = 3.6-4.7%), for seasonal periods it was higher (CV 9.2-15.5%), with the greatest variability during the winter period (CV = 15.5%). Ranking sires by the predicted proportion of gained live weight of their offspring over seasonal periods showed sire variation across different seasons. Such variation may be beneficial allowing genetic selection of animals to fit different farm systems.