Timing of insemination and fertility in dairy and beef cattle receiving timed artificial insemination using sex-sorted sperm

• Published in: Theriogenology Vol. 76; no. 3; pp. 427 - 435
• Main Authors: Sales, J.N.S, Neves, K.A.L, Souza, A.H, Crepaldi, G.A, Sala, R.V, Fosado, M, Filho, E.P. Campos, de Faria, M, Filho, M.F.Sá, Baruselli, P.S
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01-08-2011; [Oxford]: Butterworth-Heinemann; [New York]: Elsevier Science
• Subjects: Animals; artificial insemination; beef cows; Breeding - methods; Cattle; Cattle - physiology; conception; Estrous synchronization; Female; Fertility; heifers; insemination; Insemination, Artificial - methods; Insemination, Artificial - veterinary; Jersey; Male; Ovulation; Pregnancy; Pregnancy Rate; Progesterone - pharmacology; semen; Sex Determination Analysis; Sex Ratio; Sexed sperm; sires; spermatozoa; Time Factors; Time of AI; ultrasonography; zebu; Time of AI; Estrous synchronization; Cattle; Sexed sperm; Ovulation
• ISSN: 0093-691X; 1879-3231
• DOI: 10.1016/j.theriogenology.2011.02.019

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 × 10⁶ sperm/straw) or non-sorted sperm (20 × 10⁶ 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 occured 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.