Table 4-4. AVERAGE LENGTHS (days) OF ESTRUS AND ESTROUS CYCLES

Species		Estrus		Cycle

Mouse, rat	0.5		4
Hamster		1		4
Guinea pig	0.5		16
Sheep		2		17
Goat		3		20
Cattle		0.5		21
Pig		2		21
Horse		5		21
Elephant		4		22
Red kangaroo	3		35
Lion		9		55
Dog		7		60