Effect of different hormonal protocols with timed AI on clinical signs of estrus and conception rates in Bulgarian Murrah buffaloes
The objective of the field experiment was to study the effect of different protocols for estrus synchronization with timed artificial insemination (TAI) on the manifestation of clini- cal signs of estrus (CSE) and conception rates in the Bulgarian Murrah breed. For treatment 75 heifers and 133 buff...
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| Format: | Article |
| Language: | English |
| Published: |
Universidad del Zulia
2023-11-01
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| Series: | Revista Científica |
| Subjects: | |
| Online Access: | https://produccioncientificaluz.org/index.php/cientifica/article/view/43465 |
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| Summary: | The objective of the field experiment was to study the
effect of different protocols for estrus synchronization with
timed artificial insemination (TAI) on the manifestation of clini-
cal signs of estrus (CSE) and conception rates in the Bulgarian
Murrah breed. For treatment 75 heifers and 133 buffalo cows
were assigned with follicles >8 mm and no corpus luteum and
subjected to the following protocols: Presynch/Ovsynch (D1 -
Synchrostim + Enzaprost; D4 - Оvarelin; D11 - Enzaprost; D13
- Оvarelin), Ovsynch (D1 - Оvarelin; D8 - Enzaprost; D10 - Оva-
relin), Ovsynch+PRID (D1-8 PRID DELTA; D8 - Enzaprost; D10
- Оvarelin). For the buffalo cows, each protocol was applied in
the breeding and non-breeding season, while in the heifers, out
of season only. Gestation was diagnosed sonographically on
day 45 post-TAI. The data were processed via dispersion anal-
ysis of a non-orthogonal set of qualitative traits, including the
following factors with respective classes: protocol, three class-
es – as described above; CSE, three classes – without CSE;
patency of the cervical canal (excluding mucus); presence of
clear mucous discharge (including patency); age, two classes
– heifers, cows. Another 3-factor analysis was conducted on
buffalo cows only, instead of age including season – with two
classes: in season and out of season. The results show that the
factor protocol has the most pronounced effect on TAI success
(p<0.01), significantly lowest being the pregnancy rate (pi val-
ues) under the Presynch/Ovsynch protocol – only 23.9%, com-
pared to 40.7 and 47.4% under Ovsynch and Ovsynch+PRID,
respectively. Although the effect of age is non-significant, in the
heifers, Ovsynch+PRID and Ovsynch show markedly higher
results (50.0 and 52.9%, respectively). At the same time, in
the buffalo cows, the differences are lower, the Ovsynch pro-
tocol having a relatively low pregnancy rate (38.3%), Ovsyn-
ch+PRID – highest (45.0%), and Presynch/Ovsynch – lowest (30.4%). The season had no significant effect, but it is note-
worthy that there are even higher conception rates after out-of-
season TAI than in-season – a very well-expressed difference
under Ovsynch+PRID (50.0% vs. 37.5%) and smaller under
Presynch/Ovsynch (37.5% vs 28.9%) and Ovsynch (40.9% vs
36.0%). CSE is a significant source of variance of conception
rates (p<0.05), predictably the highest pi value belonging to
the cases with mucus. The superiority of the Ovsynch+PRID
protocol finds expression in the highest incidence of full estrus
(with both CSE) in the lactating buffaloes (70%) and even more
in the heifers (82%), as compared to Presynch/Ovsynch (56.5
and 52.2% respectively) and Ovsynch (51.1 and 50.0%) pro-
tocols. This is a reason to conclude that the Ovsynch+PRID
protocol is recommendable for application in both age groups
of Bulgarian Murrah buffaloes, as the observed highest mani-
festation of full estrus is associated with the highest conception
rates, for which mucous discharge can be used as an indicator;
this to greater extent regards the heifers in which, on the other
hand, the Ovsynch protocol also has high success of TAI. The
tested protocols show the capacity to mitigate the impact of
season on reproduction and can be used in practice for over-
coming the species-problematic seasonal anestrus, especially
Ovsynch+PRID.
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| ISSN: | 0798-2259 2521-9715 |