Analysis of records of embryo production in Red Brahman cows
Abstract
Records of embryo production in Red Brahman donor cows (n=50) and F1
recipients (n=531) were evaluated from the collection day to the birth of the
embryo produced. The effects of the sire of the donor and the embryo, protocol,
season-protocol, and body condition of the donor on the total number of good,
degenerated, unfertilized, and total embryos were evaluated. The number of
donors collected for protocols 1, 2, and 3 were 50, 39, and 46 respectively. The
production of good transferable embryos, and embryos/collection for protocols 1,
2, and 3 were 171 (4.6), 152 (4.6), and 208 (6.3) respectively. The final status
of each recipient was recorded as non-pregnant, resorption, abortion, and live
calf. The model used to analyze pregnancy state was: protocol, embryo stage,
embryo quality, corpora lutea size, and season. The effects of sire of the embryo,
season-protocol, protocol, embryo stage, embryo quality, body condition score,
and corpora lutea size on gestation length and birth weight were analyzed.
Season-protocol affected (P<0.05) the number of degenerated embryos. Mean
number of degenerated embryos were higher (P<0.05) during winter for
protocols 2 and 3 than during other seasons. The ratio for good embryos differed
(P<0.01) by sire of donor.
The final status of recipients was affected (P<0.01) by protocol. The maximum
percentage of live calves and the minimum percentage of non-pregnant
recipients were achieved for protocol 3. Gestation length differed (P<0.01) by sire of the embryo, season-protocol,
protocol, and body condition score. Spring-protocol 3 resulted in the shortest
while Fall-protocol 2 resulted in the longest mean gestation length. Calf birth
weight differed (P<0.05) by season-protocol and by embryo quality. The lightest
birth weights resulted from embryo quality grade 2 and from spring-protocol 3.
These results indicate that using protocols that combine 17??-estradiol, FSH
and GnRH (protocol 3) during the spring in conjunction with selection for sire of
donor can increase embryo production by Red Brahman cows. Use of protocol 3
with donors in the spring, selection of embryo sire for short gestation length and
transfer of quality grade 2 embryos can be used to minimize the incidence of
dystocia in recipients.
Citation
Riano Rocha, Edgar Hernando (2005). Analysis of records of embryo production in Red Brahman cows. Master's thesis, Texas A&M University. Texas A&M University. Available electronically from https : / /hdl .handle .net /1969 .1 /2691.