Table 1. Summary of reproductive results obtained using preserved semen with different semen extenders and times of storage in sheep.

Authors	Storage (ºC)	Preservation (h)	Semen Concentration (sperm million/dose)	Semen extenders	AI	Fertility (%)	Fertility statistics
Naim et al. (2009)	5	12	150-300 x 106	OviPro® (Biotay-Minitüb, Germany)	TAI* (54-56 h)	32	a
		24				11	b
		12-24	300 x 106			29	a
			150 x 106			14	b
Olivera et al. (2005)	5	24	120 x 106	TRIS (TRIS, fructose, citric acid, egg yolk)	AI (natural estrus)	19	a
		48				22	a
		24		“Piedra Mora” (UHT skim milk, egg yolk, glycerol)		49	b
		48				47	b
Menchaca et al. (2005)	5	12	200 x 106	TRIS, glucose, citric acid, egg yolk	AI (natural estrus)	43	a
		24				35	b
		Fresh semen				54	a
Cueto and Gibbons (2010)	5	12	300 x 106	skim milk, glucose	TAI* (52-56 h)	40	A review, no statistical analysis is presented
	15	6-8	150 x 106	skim milk		55
Hozbor et al. (2009)	18	8	---	UHT skim milk	TAI	47

TAI*: timed artificial insemination in the external uterine orifice; hours (h) after sponge withdrawal;

TRIS: hydroxymethyl aminomethane; UHT: ultra high temperature; AI: Artificial insemination. Different letters differ considering P<0.05.