Energy intake and patterns of growth for male and female fallow deer of two genotypes, between 10 and 21 months of age

Abstract

AbstractEuropean (no. = 36) and hybrid (¼ Mesopotamian, ¾ European; no. = 36) fallow deer (Dama dama) were evaluated for weight gain and energy intake from 10 to 21 months of age. Twelve each of bucks, does and castrated males (haviers) were tested for each genotype, in both concentrate-fed and pasture-based feeding systems. Based on weekly weighing hybrids (H) in each of the sex classes grew more rapidly (5 g/day across all groups) than the European (E) fallow deer (P < 0·05). Haviers given concentrates grew significantly faster than pasture-fed haviers (P < 0·01), whilst does grown on pasture grew significantly faster than those given concentrates (P < 0·01). There was no significant difference in pattern of growth between bucks on pasture and those given concentrates (P > 0·05). Does grew significantly less (P < 0·01) than bucks and haviers in spring, summer and winter but environmental differences between years could not be accounted for in the analysis.Animals of all sexes and genotypes experienced rapid growth from 10 to 12 months of age (spring) and this was associated with energy intakes according to metabolic body weight (M0·75) these ranging between 0·8 and 1·1 MJ metabolizable energy (ME) per kg M0·75 per day. There were significantly (P < 0·01) higher levels of energy consumed by H does and haviers in the summer, compared with their E counterparts but this was not associated with greater growth rates. However, H does had significantly higher (P < 0·01) dressing proportions at slaughter than E does. The energy intake on a metabolic body weight basis for most groups declined to between 0·7 and 0·8 MJ ME per kg M0·75 per day from 12 to 21 months of age, except for the does, which declined even further to between 0·5 and 0·6 MJ ME per kg M0·75 per day from 17 months of age.There were no significant differences between E and H deer for energy intakes per M0·75, and H deer were slightly more energy efficient than their E counterparts in terms of growth rate in relation to annual gross energy intake. The food intake : weight gain ratio increased considerably for both genotypes after 14 months of age, indicating the desirability for slaughtering as soon as animals reach the target live weight. It was concluded that the crossbreeding system described is production efficient and produced offspring that reached slaughter weight sooner than E fallow deer and thereby produced carcasses with a greater wholesale value than their E counterparts of the same age.