Most of the available research focuses on reducing the amount of time the kits nurse on the doe (so there is less stress on the doe) without an increase in mortality or decrease in body weight of the kits. So, with that in mind...
I was able to find a review of weaning strategies. Here are a summary of the results.
In experiments that compared different weaning ages, 14 days is definitely too young.
There were mixed results with weaning at 18-21 days.
Xiccato et al (2000) and Trocino et al (2001) observed that early weaned kits (21 and 25 days) showed a lower weight at 32 days than those wened at 28 and 32 days, but the 4 groups presented a similar weight at 56 days with no difference in mortality. Similar results have been recently obtained by Gidenne and Fortun-Lamothe (2001) although a higher mortality during the late weaning period (32-45 days) was registered for early weaning kits.
The author suggests exploring weaning between 21-25 days, but this may not be desirable in a pet breeding environment since we are not trying to maximize production and there may be some risk to the kits.
The author does suggest that kits perform better if fed special weaning diets.
formulation has to be considered that: a) the kits do not have a great capacity for carbohydrate digestion b) the type of protein and fat used could affect their following performance, and c) a high solid food intake should be promoted to improve the maturity of their digestive system.
The Food and Agriculture Organization of the United Nations's book The Rabbit: Husbandry, health, and production is an often quoted source of standards in rabbit breeding and managment. The guidelines on weaning give ranges from 28-42 days, and depend on the reproductive rate you want out of the doe. In particular, the authors state:
Later weaning is in no way advantageous except for fryer production - very young animals which can be sold at eight weeks and have not undergone weaning shock.
In addition, they also recommend
Where the quality or quantity of the feed is not up to standard, it is preferable to
wean rabbits at about 40 days
- Can kits be weaned at 4 weeks old? Yes
- What is the best time to wean kits? Weaning ages seem to vary from 21-42 days (and perhaps more). It depends on your goals/strategies. A pet or fancy/show breeder will wean at a different time from a breeder selling fryers and they will both wean at a different time from a breeder selling roasters.
Weaning strategy review: Pascual, J.J. Early Weaning of Young Rabbits: A Review. World Rabbit Science 2001. Vol 9 (4) 165-170.
References cited in quotes from the Weaning Strategy Review:
Xiccato, , Trocino A, Sartori A, Quaque PI, 2000. Early weaning of rabbits: effect of age and diet on weaning and post-weaning performance. Proc. 7th World Rabbit Congress Valencia Vol C 483-490.
Trocino A, Xiccato G, Sartori A, Queaque PI. 2001 Effect of starter diet and weaning age on growth, caecal fermentation and body composition of young rabbits. 2nd meeting of workgroup 3 and 4. COST Action 848, Godollo, Hungary.
Gidenne T, Fortun-Lamothe L 2001. Early weaning effect on performance and health. 2nd meeting of workgroup 3 and 4. COST Action 848