Time-mating

The animals are housed in cages which comply with the company s own SOP s and relevant national legislation. Animals may be multiply housed, although many investigators prefer to house animals singly. When animals are multiply housed, cage-mates should be mated on the same day this is normally only possible when animals have been time-mated at the supplier. 

In-house mating is recommended in the Redbook. There are no valid reasons for this. Time-mated animals are available from many reputable laboratory animal breeders and their use has been validated over several decades. The use of time-mated animals allows a predefined number of pregnant females to be ordered and allocated to the study each day so that all procedures can be planned in advance according to the resources available. Also, the supplier has a large colony of breeding males and females available, providing a wide gene pool. 

Specification Pregnant females since time mated females are not commercially available, a mating program has to be established on-site Pregnant females since time mated females are not commercially available, a mating program has to be established on-site... 

Selection of females Females are time mated on theoretical day 13 of their menstrual cycle. 

Pregnant females since time mated females are not commercially available, a mating program has to be established on site... 

Animals Time-mated pregnant rats at an age of 9-10 weeks at the time of breeding. The range of rat body weight is 200-225 g. 

Obtain a time mated female Balb/c mouse 10 d into the pregnancy and maintain in standard cage used for mouse breeding. 

The cumulative prenatal loss rate for cynomolgus monkey until GD 150 across a 9-year period (1984 to 1993) was 14.8 % (65 losses in 439 pregnancies) [7] (Table 18.8). In our experience, cumulative prenatal loss rate in control animals was 12.9% (40 losses in 311 timed pregnancies) until GD 150 in time-mated toxicity studies across a 10-years period (1994-2004). The vast majority of prenatal losses occurred prior to GD 100. Interestingly the frequency of... 

TABLE 18.8 Cumulative prenatal loss rates in timed-mated cynomolgus monkeys... 

Acute oral LD50 values for mice were reported to be 1,230 mg/kg (Carpenter et al. 1956) and 1,519 mg/kg (Eastman Kodak 1988). When time-mated CD-I mice were treated by gavage on gestational days... 

Scheme l. GEKEE E>CPERIMENrAL FRQdDOOL. Timed Mating of hyt/hyt Male X hyt/ + Female 1... 

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