1. Abstract
The scientific interest in camels (Camelus dromedarius) has been increasing dramatically in the past three decades as the steeply rising number of publications on this subject demonstrates. Parallel the camel has gained economic importance in many African and Asian countries with large arid and semi-arid areas which lend themselves to efficient exploitation through camel husbandry. Furthermore new, intensive camel production systems are emerging and new camel products are becoming of interest for certain high price markets. This raises the interest in the expansion of camel populations. One of the key constraints to faster expansion of camel herds is the well documented slow reproduction. Consequently considerable research effort has been successfully expended on the biology of camel reproduction ranging from behavioural, hormonal, physiological, histological and medical aspects to the adoption of modern breeding techniques such as artificial insemination and embryo transfer. However, not much of this research was carried out under field conditions or with larger numbers of animals and the impact of its results on the vast majority of camel herds existing in marginal and remote areas has remained minimal. We discuss the effects of other than the inherent biological constraints of camel reproduction arising from the management systems applied, the prevalent production objectives, the degree of commercialisation of production and market integration, and from the seasonal and annual fluctuations of environmental conditions. We formulate relevant research needs with specific emphasis on applicability in production environments. We outline possible research project approaches.
Keywords: Camels, herd growth, non-biological reproduction constraints, research needs

2. Figure 1: Theoretical stable age structure of the females in a camel herd and resulting reproductive value of each age class
The stable age structure is based solely on inherent biological/physiological parameters such as age at sexual maturity, conception rate, gestation length, foetal mortality, length of calving interval, lactation anoestrous, and breeding seasonality as typical for a pastoral herd in northern Kenya. The resulting potential reproductive value would allow an 8 -10% annual herd growth, similar to that of feral dromedaries in Australia.
Figure 2: Recorded age structure of female camels in an existing pastoral herd and the observed number of births by age group
Figure 2 describes the real life age structure in a pastoral herd where irregularities in the age pyramid are caused by environmental, production system, and management/health constraints. Herd growth in this situation ranges between nil and 3% and can even be negative. The annual variation of reproductive performance is extremely high.

3. Figure 3: Example - Breeding seasonality in three camel herds in equatorial East Africa
Dromedary herds were observed in three different locations in equatorial East Africa. The locations are all situated between 1° and 2 ° Northern latitude, but with distinctly different rainfall patterns, i.e. different seasonal forage supply.
The three herds under observation showed distinctly different seasonal calving patterns. Calving season was solely determined by rainfall, i.e. forage supply, as there is no possible photoperiodic effect so near the equator. The longer the calving season, the greater is the chance of an early pregnancy after stillbirths, loss of calf or early weaning.
This is demonstrated by the resulting calving intervals [months] in the three locations:
Marsabit = 28, Mogadishu = 30, Rumuruti = 20
Potential interventions which require investigation: Supplementary feeding of females, flush feeding of breeding males, early weaning of male calves and reduction of milking period of their dams.

4. Figure 4: Example effect of production system
Simulation of the upper (high) and lower (low) thresholds of camel herd size in 4 production systems after 25 years, based on an initial herd size of 100 breeding females aged 3 years, estimated at two levels of probability. The correlation between milk off-take and herd growth is evident. Although there are factors involved as well.
Antagonistic Production Targets
Herd 1 Research Station, no milk off-take
Herd 2 Ranch herd, limited milk off-take
Herd 3 Nomad herd, max. milk off-take
Herd 4 Nomad herd, limited milk off-take
High milk production/off-take and high herd growth are antagonistic production objectives. However, our understanding of physiological, nutritional, health, and environmental factors in this antagonism is still poor; particularly so under field conditions in pastoral systems.
Investigations of past herd growth on a broad scale should be carried out in numerous camel herds at different locations using the “progeny history method” to acquire solid information of herd demography under varying ecological and economic conditions.

5. Conclusion: Perceived Research Needs
Figure 5: Current Research Emphasis
A survey of papers on camels done on revealed a steep and parallel increase in the past three decades in the relevant disciplines.
A strong emphasis in reproduction related research is on all aspects of assisted reproduction in intensive camel milk production, applicable to not more than two percent of the world’s camel population
Conclusion: Perceived Research Needs
Can age at first calving be reduced in pastoral production systems?
Can parturition intervals be shortened in pastoral production systems?
Can breeding seasons be extended by feeding programmes for male and/or female camels?
More information needs to be collected on herd structure in various ecological, economic, and geographic contexts.