The strain or race -the environmental factors such as Ii-temperature,light,season,etc Nutrition Social factors

The stage of development where the animal reaches sexual maturity -the opening of vagaina in the female -the descent of the testicle in the scrutum in the male Laboratry animals are mated for the first time shortly after the signs of puberty

From puberty onwards, the genital tract in the female undergoes a series of cyclical and repetitive transformatios called estrus which consists of four phases called, proestrus, estrus,meestrus, and diastrus The length of the cycle varies from one species to another

It is important for the animal breeder to know when the animal is in estrus phase, since it is then that she can be fertilized -she is receptive to the male -ovulation takes place Spntaneous induced

During psuedogestation the female is not receptive

-the biological features of the species -the type of the animal required -production requirment Permanent mating, the female is not separated after parturition 1. 1.monogamous 2. 2.polygamous 3. Temprary mating 4. 1.polygamous or harem type monogamous

timerabbitGuinea pigratmouse Weeks weeks Age at puberty Male female Weeks weeks Mating first Male female days Length of cycle days6-15 hours9-20 hours7-20 hoursLength of estrus hours10-13 after mating hours after beginning of estrus Time of ovulation After parturition _3- 8 hours28 hoursWithin 28 hours Postpartum estrus

days Length of pregnancy Number of young per litter 6-8 weeks14-25 days21 days16-21Length og lactation years Length of fertile period Male female grams gr1-1.5 grAverage weight at birth

1.1 puberty -female, opening of vaginal at 28-49days -male maturation of spermatozoa at 45 days

4 to 5 days and depends on 1.Strain 2’social environment The estrus lasts 7-20hours

An estrus occur 14 to 28 days after parturition

Spontaneous ovulation Takes place 2-3 hours after beginning of estrus

Check the vaginal plug. Remains hours -to know dated embryo -cesarean cases

Non suckling female Hybrids have a shorter period of gestation Suckling female If the number of suckling is 1-2 gestation is prolonged 7 days If the number is more than 3 the gestation is delayed by days

Lasts 11 days Common in female grouped together

Takes place at any time Three and a half hours foe a litter of 11

lasts 4 weeks Milk is high until 10 days Tput the male in separate cages -during weaning never put more than 30 hey eat solid food at 14 - make sure weaning takes place at 21 During weaning never put more than 30 animals in one cage -

The first mating 6 to 8 weeks Mice should not be paired off after the age of 12months Breeding animals sacrificed months Permanent mating most often used One male to two to six female

2.1 puberty Female vaginal opening48 to 60 days Male testicle descend 40 days

The female rat has a cycle of 4-5 days To detect the estrus -use the vaginal smear -observe the behaviour of animal -hyperactive -hallow back

Vaginal plug eliminated very quickly

3.1Puberty Female: the vagina is usually covered by an epithelial membrane which disappear during estrus and parturition The first rupture of vagina membrane takes place at age of 58 days and the first estrus 68 days Male: 68 days

Average length 16 days depending on the strain and individual, the onset of estrus is as follow

Vaginal plug is not always present

Average 68 days Litter of 5,67

The new born are very advanced in age The pubic symphysis dilate 24-to 36 hours the pubic symphysis is mm

3-5 animals: g 1 animal: 140 g -sacrifice the animal whose birth is below 50gr

21-28 days When they reach 170 – 180 gr -separate male from female

Males: weeks Female Female weighing 400 gr with male of 500 gr

a. Unit comprising 1 male and 4-6 female b. Units comprising c. 10 females to 1 male

The females are not separated from the mating unit

4.1 Puberty -small breed 4 months -middle breed 4-7 months -large breed 9-12 months -male:6-7 months

12-16 days -the vulva is congested -the female is agitated -ovulation takes place hours after stimulation

Female if receptive adopts a hollow back posture -the individual -the physiological condition -circumstances Males quickly falls

31 to 32 days

Psuedogestation last 16 to 17 days

-making the nest -food consumption drops -delivery takes 30 minutes, sometimes hours or days