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Reproduction, Fertility and Development Reproduction, Fertility and Development Society
Vertebrate reproductive science and technology
RESEARCH ARTICLE

77 Evaluation of sexed semen on conception and pregnancy loss rates in synchronized Bos indicus, Bos taurus-indicus, and Bos taurus cows following timed artificial insemination

T. L. Mashilo A B , M. L. Mphaphathi A , A. Maqhashu B , M. R. Ledwaba A B , M. A. Thema A , M. D. Sebopela A and T. C. Chokoe C
+ Author Affiliations
- Author Affiliations

A Agricultural Research Council, Animal Production, Germplasm Conservation & Reproduction Biotechnologies, Private Bag X 2, Irene, 0062, RSA

B University of the Free State, Department of Animal, Wildlife and Grassland Sciences, Bloemfontein, Republic of South Africa

C Department of Agriculture, Land Reform and Rural Development, Directorate: Farm Animal Genetic Resource, Pretoria, Republic of South Africa

Reproduction, Fertility and Development 36(2) 190 https://doi.org/10.1071/RDv36n2Ab77

© 2024 The Author(s) (or their employer(s)). Published by CSIRO Publishing on behalf of the IETS

The present study aimed to evaluate oestrus expression, conception, and pregnancy loss rates following timed AI (TAI) with sexed or unsexed semen in beef cows. Postpartum suckled or dry Bos indicus (Brahman; n = 32), Bos taurus-indicus (Bonsmara; n = 33), and Bos taurus (Nguni; n = 30) cows from emerging cattle farmers in South Africa were assigned to a 9-day Ovsynch + controlled intravaginal drug release (CIDR®) protocol followed by TAI. On a random day of the oestrous cycle (Day 0) cows received CIDR® (1.9 g of progesterone, Pfizer Laboratories) inserts and 2 mL intramuscularly (IM) administration of oestradiol benzoate (EB, VTech). On Day 8, oestrus detection aids were applied with 2-mL intramuscular injection of prostaglandin F2α (PGF2α; Estrumate®, Intervet) and CIDR® removal. Cows received 1-mL IM injection of EB on Day 9. Oestrus expression was evaluated before TAI, and cows received TAI 55 h following CIDR® removal with sexed or unsexed semen from four Angus sires. Pregnancy was diagnosed by transrectal ultrasonography 35, 65, and 95 days following TAI to determine pregnancy loss for first (between Days 35 and 65) and second (between Days 66 and 95) periods of pregnancy. Data were analysed using logistic regression procedure and chi-squared test to determine significant differences in the effect of oestrus expression and semen type on conception and pregnancy loss rates. Oestrus expression was similar for all cattle subspecies (P > 0.05). Conception rates and pregnancy losses were compared within and across per cattle subspecies (indicus vs taurus indicus vs taurus), per day (35, 65, 95), and per semen type (sexed vs nonsexed). It was concluded that conception and pregnancy loss rates vary among cattle subspecies when utilising sexed semen.

Table 1.The influence of sexed semen on timed AI conception and pregnancy loss rates in beef cows

Cattle subspeciesOestrus expressionSemen typeConception ratePregnancy loss
Day 35Day 65Day 95Between Days 35 and 65Between Days 66 and 95
Bos taurus indicus20/33 (60.6%)Sexed7/15 (46.7%)6/15 (40.0%)6/15 (40.0%)1/7 (14.3%)0/6 (0.0%)
Unsexed9/18 (50.0%)8/18 (44.4%)8 /18 (44.4%)1/9 (11.1%)0/8 (0.0%)
Bos indicus21/32 (65.6%)Sexed11/14 (78.6%)9/14 (64.3%)8/14 (57.1%)2/11 (18.2%)1/9 (11.1%)
Unsexed11/18 (61.1%)6/18 (33.3%)6/18 (33.3%)5/11 (18.2%)0/6 (0.0%)
Bos taurus21/30 (70.0%)Sexed10/20 (50.0%)5/20 (25.0%)5/20 (25.0%)5/10 (50.0%)0/5 (0.0%)
Unsexed4/10 (40.0%)3/10 (30.0)3/10 (30.0%)1/4 (25.0%)0/3 (0.0%)