única ou dupla insemina？？o artificial em tempo fixo em porcas com ovula？？es induzidas pelo Horm？nio Luteinizante

two hundred fifty four sows camborough 22 (pic？), were divided in 3 treatments: t 1 (n=60) - 600 ui of ecg after weaning and 5 mg of lh, after 72 h, with single artificial insemination (ai) (24 h after lh); t 2 (n=95) - same hormonal treatment of t1, with 2 ai (24 and 32 h after lh); t 3 (n=99) - control group, with 3 ai. the averages of weaning-to-estrus interval (wei) in t1, t2 and t3 were of 87,4 ± 3,0 (87 - 111), 87 ± 0 (87) and 99,9 ± 13,6 (63 - 135) h, respectively, been reduced (p < 0,0001) by gonadotropins. the duration of estrus (de) were of 44,3 ± 8,78 (12 - 60), 41,3 ± 9,77 (24 - 60) and 60,1 ± 10,22 (36 - 84) h, respectively for t1, t2 and t3, showed lower (p < 0,0001) in treated sows. fourteen of 155 sows that received gonadotropins (9,03 %) didn't show oestrus. among these, 10 return to estrus, denote 40% of the total returns. the diferences in lh to ovulation interval (lh-ov) among control group (56,1 ± 15,91, range: 21 - 93 h) and treated groups (35,7 ± 6,07 in t1 and 35,5 ± 6,06 in t2, range: 30 - 42 h) were significant (p < 0,0001). the litter size (ls) were of 10,6 ± 3,25 (2 - 16) in t1, 11,3 ± 3,0 (4 - 20) in t2 and 11,6 ± 2,74 (4 - 18) in t3, while the same demonstred number of piglets born alive (ba) of 9,6 ± 3,14 (2 - 16), 10,5 ± 2,83 (1 - 18) and 10,5 ± 2,73 (4 - 16). in both tl (p = 0,11) and nv (p = 0,06) there weren't any diference. the farrowing rate (fr) in t1, t2 and t3 were, respectively, 76,67 %, 88,42 % and 91,92 %, been diferent between t1 and t3 (p = 0,01). the gonadotropins were effetive in the ovulation induction and synchronization; the use of 2 ai maintained the reproductive index and, however the single ai do not show significance in ls, there is necessity of new reserchs in this area.