Seasonal effects of two forage-based nutrition regimens on intake and average daily gain of three genotypes of young red deer (Cervus elaphus)

The red deer genotypes currently being farmed in New Zealand have different forage-use habits and exhibit different growth profiles in different seasons. Three genotypes (NZ red, eastern European and elk-cross) were subjected to low and high nutritional regimens during autumn, winter and spring. Few differences among genotypes were found in autumn, but in winter the elk-cross genotype grew faster than did the NZ red and eastern European genotypes. NZ red deer consumed approximately 9% of their diet as hay in both autumn and winter, while eastern European and elk-cross deer had much higher intakes of hay (up to 44%). Divergence in response to the high- or low-nutrition regimens imposed developed in winter. Liveweight gain averaged 84 g/d on the low nutrition regimen and ranged from 132 to 199 g/d for NZ red and elk-cross genotypes respectively on the high-nutrition regimen. Eastern European deer were immediate. In spring as the NZ red genotype did not respond to increasing feed availability, while the eastern European and elk-cross deer increased growth rate by approximately 50 g/d and 100 g/d, respectively, in response to increased feed availability. This was matched by increases in forage and metabolisable energy intake. Understanding these interactions provides information that will enable feeding systems to be tailored to deer genotype to improve on-farm resource-use efficiency.