Environmental constraints on reproductive performance of farmed deer

• Published in: Animal reproduction science Vol. 42; no. 1; pp. 35 - 44
• Main Authors: Asher, G.W., Fisher, M.W., Fennessy, P.F.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 1996
• Subjects: cervidae; Deer; environmental factors; facteur du milieu; factores ambientales; performance de reproduction; reproductive performance; Reproductive performance-deer; reproductividad; Deer; Reproductive performance-deer
• ISSN: 0378-4320; 1873-2232
• DOI: 10.1016/0378-4320(96)01501-1

Optimum reproductive efficiency of farmed deer is often constrained by apparent maladaptation of wild cervids to a given farm environment or components of that environment. Seasonal breeding amongst forest-fringe species of northern temperate origin (e.g. red deer, fallow deer) benefits the species within its natural range, but often creates misalignment in southern temperate zones between the high nutritional demands of lactation in summer and the earlier peak of pasture production and quality occurring in spring. This can lead to increased calf mortality, decreased calf growth rates and depressed dam liveweights. Much emphasis has been placed on manipulating either pasture production patterns or the timing of birth to create better synchrony between the two. The latter largely involves artificial manipulation of the timing of conceptions (e.g. melatonin treatment), but there may also be options for genetic selection of deer for earlier calving patterns. Tropical cervid species farmed in temperate environments can exhibit either aseasonal reproduction (e.g. chital deer) or autumn-wintering calving patterns (e.g. rusa deer), leading to high mortality of neonates (hypothermia, predation) under uncontrolled breeding management. However, there are simple management options to synchronise and shift calving patterns to better align tropical species to temperate environments. The effects of chronic and acute stress on reproductive efficiency of farmed deer are often discussed but seldom demonstrated. Many farmed deer populations exhibit high pregnancy rates (i.e. > 90% females pregnant), indicating robust reproductive physiology and general habituation to the farmed habitat. Low reproductive rates of pubertal red deer hinds in some herds may be partly indicative of the effects of chronic stress, although other factors such as social facilitation and nutrition cannot be discounted. While species of cervids that are used for farming generally display a high degree of behavioural plasticity, the farm environment and associated management practices may impinge on important components of the social environment. Thus, practices such as controlled breeding (e.g. single-sire mating) and confinement during calving may have effects on reducing overall reproductive potential by disrupting social processes (e.g. dam—calf bonds). This highlights the paucity of knowledge on the complexities of cervid behaviour and their implications in both wild and farmed deer.