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Discoveries in Agriculture and Food Sciences - Vol. 11, No. 1
Publication Date: February 25, 2023
DOI:10.14738/dafs.111.13862.
Arega, A., Aredo, T. A., & Chalchissa, G. (2023). Effect of Timing of Artificial Insemination on Fertility of Cows and Calf Sex Ratio in
Arsi Cows. Discoveries in Agriculture and Food Sciences, 11(1). 43-47.
Services for Science and Education – United Kingdom
Effect of Timing of Artificial Insemination on
Fertility of Cows and Calf Sex Ratio in Arsi Cows
Alemayehu Arega
Adami Tulu Agricultural Research Center
Tesfaye Alemu Aredo
Oromia Agricultural Research Institute
Girma Chalchissa
Adami Tulu Agricultural Research Center
Abstract
An on-station study was conducted to investigate the effect of the interval between
artificial insemination (AI) and the beginning of estrus on the fertility and sex ratio
of offspring in Arsi cows. Standing to be mounted was considered the beginning of
estrus, and artificial inseminations were made 6 h (Group 1), 12 h (Group 2), 18 h
(Group 3) and 24 h (Group 4) after the onset of estrus in the cows. Overall, 50 cows
with parity between 2 and 4, body weight ranging from 250 to 300 kg were used for
the purpose of this study. Ovulation was synchronized by administration of PGF2α
hormone. Pregnancy diagnosis was performed by rectal palpation at 90 to 120 days
post AI. Pregnancy rates were 60%, in each of the Groups 1, 2, 3 and 50% in group
4. The highest female to male ratio (P=0.041) of calves was obtained in Group 1.
Whereas the highest male to female ratio was recorded in group 4. The number of
artificial inseminations per pregnancy was within the economical limits in all
groups. In conclusion, the results of this study indicated that the variation in time
interval between the onset of estrus and artificial insemination alters the sex ratio
of offspring in Arsi cows without affecting fertility parameters.
Key words: Artificial insemination time; fertility rate; calf sex ratio; Arsi cows
INTRODUCTION
Artificial insemination (AI) has been defined as a process by which sperm is collected from the
male, processed, stored and artificially introduced into the female reproductive tract for the
purpose of conception (Morrow, 1985; Webb, 2003). When AI was being developed and
confirmed, there were several studies that were designed to determine the optimal time of AI
in relation to estrus (Aschbacher et al., 1956). Figures suggested that optimal pregnancy rate
per AI would be achieved from mid-estrus until a few hours after the end of estrus. Since then,
the recommended practice has been inseminating cows 12 h after the first observed estrus
(a.m.- p.m. breeding). However, because of the variability of interval between the onset and the
observation of estrus, it is difficult to define the ideal time of AI in relation to ovulation (Foote,
1979).
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Discoveries in Agriculture and Food Sciences (DAFS) Vol 11, Issue 1, February- 2023
Services for Science and Education – United Kingdom
In Ethiopia, there is high demand for female crossbred calves by dairy producers from artificial
insemination services (Bekele, 2005). However, due to different reasons the number of
improved heifers in the country is very low.
The use of modified flow cytometry to separate the X and Y sperm populations (sorted sperm),
and using the corresponding type to perform AI is a proven and reliable techniques for selecting
the gender of offspring. However, it is still the most expensive method for commercial
applications (France et al., 1992; Seidel et al., 1999). Sex ratio manipulation can reasonably
improve the effectiveness of selection and genetic improvement programs, through the
differential increment of males or females born after Artificial insemination (Seidel, 2003).
Several efforts have been made to alter the sex of calves by varying time of insemination in
different breeds of cattle and environments (Pursley et al., 1998; Martinez et al., 2004). It has
been recommended that early inseminations (i.e. far before ovulation) would result in more
female calves whereas late inseminations (i.e. close to ovulation) would result in more male
calves due to different timing of capacitation and survival time of the X- and Y-chromosome
bearing spermatozoa in the female reproductive tract (Martinez et al., 2004). However, there is
lack of information on suitable insemination time after onset of estrus to alter the ratio of sex
in new born calves without affecting fertility of cows in Arsi cattle. Therefore, the objective of
the present study was to evaluate the effect of various intervals of AI on the fertility of cows and
sex ratio of calves in Arsi cows.
MATERIALS AND METHODS
Study Area
The study was conducted at Adami Tulu Agricultural Research center located at 167km south
of Addis Ababa at latitude of 70 9’ N and 3807’E longitude in semi-arid middle rift valley of
Ethiopia. The area is situated at 1500 meters above sea level and the soil type of the area is fine,
sandy loam with sand, clay in the proportion of 34:48:18 respectively. The average annual rain
fall is 760mm. The minimum and maximum temperature are 12.6 and 270c, respectively
(ATARC, 2003).
Experimental Animals, Feeding and Housing
Arsi cows reared on station were selected based on their age, parity and body condition. They
were used as a dam line for the study. The semen of Holstein Frisian breed was used as a sire
line.
The study was conducted on 50 Arsi cows with parity between 2 and 5 and average body weight
of 280 kg. The study was conducted over a period of 18 months (from January 2019 to June
2020). The cows were allowed to graze natural pasture and concentrate supplement was given
in the morning and afternoon according to their production level. The animals were housed in
free stalls with a concrete slatted floor.
Synchronization, Estrus Detection and Artificial Insemination
Experimental animals were checked for pregnancy through rectal palpation before injecting
with hormone PGF2α. Those which were negative to pregnancy test were injected with PGF2α