Timing of insemination and fertility in dairy and beef cattle receiving timed artificial insemination using sex-sorted sperm
ABSTRACT The objective was to evaluate the effects of timing of insemination and type of semen in cattle subjected to timed artificial insemination (TAI). In Experiment 1, 420 cyclic Jersey heifers were bred at either 54 or 60 h after P4-device removal, using either sex-sorted (2.1 × 10(6) sperm/straw) or non-sorted sperm (20 × 10(6) sperm/straw) from three sires (2 × 2 factorial design). There was an interaction (P = 0.06) between time of AI and type of semen on pregnancy per AI (P/AI, at 30 to 42 d after TAI); it was greater when sex-sorted sperm (P < 0.01) was used at 60 h (31.4%; 32/102) than at 54 h (16.2%; 17/105). In contrast, altering the timing of AI did not affect conception results with non-sorted sperm (54 h = 50.5%; 51/101 versus 60 h = 51.8%; 58/112; P = 0.95). There was an effect of sire (P < 0.01) on P/AI, but no interaction between sire and time of AI (P = 0.88). In Experiment 2, 389 suckled Bos indicus beef cows were enrolled in the same treatment groups used in Experiment 1. Sex-sorted sperm resulted in lower P/AI (41.8%; 82/196; P = 0.05) than non-sorted sperm (51.8%; 100/193). In addition, there was a tendency for greater P/AI (P = 0.11) when TAI was performed 60 h (50.8%; 99/195) versus 54 h (42.8%; 83/194) after removing the progestin implant. In Experiment 3, 339 suckled B. indicus cows were randomly assigned to receive TAI with sex-sorted sperm at 36, 48, or 60 h after P4 device removal. Ultrasonographic examinations were performed twice daily in all cows to confirm ovulation. On average, ovulation occurred 71.8 ± 7.8 h after P4 removal, and greater P/AI was achieved when insemination was performed closer to ovulation. The P/AI was greatest (37.9%) for TAI performed between 0 and 12 h before ovulation, whereas P/AI was significantly less for TAI performed between 12.1 and 24 h (19.4%) or >24 h (5.8%) before ovulation. In conclusion, sex-sorted sperm resulted in a lesser P/AI than non-sorted sperm following TAI. However, improvements in P/AI with delayed time of AI were possible (Experiments 1 and 3), and seemed achievable when breeding at 60 h following progestin implant removal, compared to the standard 54 h normally used in TAI protocols.
SourceAvailable from: Pietro S Baruselli[Show abstract] [Hide abstract]
ABSTRACT: The present study evaluated the use of sex-sorted sperm upon estrus detection (ED) or following timed artificial insemination (TAI) in lactating dairy cows. Additionally, the effect of the presence of a corpus luteum (CL) at the beginning of the TAI protocol was verified. Cows (539 crossbred Gir × Holstein and 87 Holstein) were classified according to the presence or absence of CL by ultrasonography exam. Cows with a CL were randomly assigned into one of two groups (CL-ED/AI or CL-TAI), and cows without a CL (NoCL-TAI) received TAI. Cows from the CL-ED/AI group received 500mg of cloprostenol intramuscularly and were inseminated 12h after ED in the following five days. Cows from the TAI groups (CL or NoCL) received TAI. Cows receiving CL-ED/AI had a lower (P<0.0001) service rate (45.1%, 101/224) than TAI groups (CL-TAI=94.2%, 180/191 and NoCL-TAI=97.2%, 205/211). However, cows receiving AI upon ED (CL-ED/AI=31.7%, 32/101) presented higher (P=0.03) pregnancy per AI (P/AI) than cows bred following TAI (CL-TAI=19.4%, 35/180 and NoCL-TAI=23.9%, 49/205). Despite the lower P/AI, cows receiving TAI presented greater (P=0.07) proportion of pregnant cows at the end of the reproductive program (CL-TAI=18.3%, 35/191 and NoCL-TAI=23.2%, 49/211) than those inseminated upon ED (14.3%, 32/224). There was no effect (P=0.45) of the presence of a CL at the beginning of the synchronization protocol on P/AI. Thus, the use of TAI programs, regardless of the presence of CL in the beginning of the synchronization protocol, increases the service and pregnancy rates but reduces the P/AI when compared to the use of sex-sorted sperm upon ED.Animal reproduction science 11/2013; 143(1-4). DOI:10.1016/j.anireprosci.2013.10.014 · 1.58 Impact Factor
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ABSTRACT: This experiment was designed to test the hypothesis that delayed insemination of non-estrous cows would increase pregnancy rates when using sex-sorted semen in conjunction with fixed-time artificial insemination (FTAI). Estrus was synchronized for 656 suckled beef cows with the 7-day CO-Synch + CIDR protocol (100 μg GnRH + CIDR [1.38 gm progesterone] on d 0; 25 mg PGF2α at CIDR removal on d 7; and 100 μg GnRH on d 10, 66 h after CIDR removal). Estrus detection aids (Estrotect) were applied at PGF2α and CIDR removal on d 7, and estrous expression was recorded at GnRH on d 10. Cows were assigned to one of three treatments: (1) FTAI (concurrent with GnRH, 66 h after CIDR removal) with conventional semen regardless of estrous expression; (2) FTAI with sex-sorted semen regardless of estrous expression; or (3) FTAI with sex-sorted semen for cows having expressed estrus, and delayed AI 20 h after final GnRH for cows failing to express estrus. A treatment x estrous expression interaction was found (P < 0.0001). Higher pregnancy rates (P < 0.0001) were achieved with conventional semen (Treatment 1, 77%) than with sex-sorted semen (Treatments 2 and 3, 51% and 42%, respectively) among cows that expressed estrus. However, among cows that failed to express estrus, delayed insemination with sex-sorted semen yielded higher (P < 0.0001) pregnancy rates than with sex-sorted semen at the standard time (Treatments 2 and 3, 3% versus 36%, respectively). Furthermore, among cows that failed to express estrus, FTAI pregnancy rates when using sex-sorted semen at the delayed time (36%) were comparable (P = 0.9) to those achieved using conventional semen at the standard time (Treatment 1; 37%). These results indicate that delaying AI of non-estrous cows by 20 h from the standard FTAI improves pregnancy rates when sex-sorted semen is used with FTAI.Journal of Animal Science 02/2014; 92(4). DOI:10.2527/jas.2013-7131 · 1.92 Impact Factor
Dataset: CFCS 2013 Vol. 49