Genetic and Management factors affecting conception rate, early pregnancy and embryo loss in Norwegian Red cows
Low fertility and embryo loss is an increasingly significant production problem in bovine dairy production in
Europe. It is therefore of great concern that we have seen a reduction in non-return rate (NRR) and the national
fertility index during the last three years in Norway.
Embryo mortality (EM) is the most important cause of return to estrus and results in significant economic loss for
the dairy industry. EM may have different causes, among them genetic, nutritional and infectious. In the proposed
project, we aim to elucidate the most significant causes of EM in NR with a special focus on bulls with high or low
NRR. By investigating embryonic gene expression in relation to male genetics and male and female physiological
factors, we seek a genetic link to embryonic death in NR.
A clinical study will be performed in maximum 74 heifers in two parts at SHF, NMBU.
• 1) 12 heifers will be superovulated and inseminated with semen from bulls with either high or low NRR ,
respectively. On day -8, the embryos will be collected through embryonic lavage, morphologically quality
evaluated, frozen and later exposed to gene expression studies. If necessary, part 1 will be repeated.
• 2) 50 heifers will be followed carefully until day 42 of pregnancy to catch late embryo loss.
Repeated clinical examinations including body condition score (BCS), rectal palpation, ultrasound and sampling of
blood will be performed. Focus will be nutritional condition, hormones, pregnancy associated factors, endometritial
samples and in case of embryo loss, uterine biopsies.
The heifers will follow a normal pregnancy and calving after the studies are finished.
The heifers will live the normal life of dairy cattle with a few more examinations than usual:
1) Blood sampling.
2) Clinical examinations
3) Superovulation, insemination and collection of embryos (part 1). On the day of embryo collection, the animals will be
sedated and given epidural anesthesia.
Expected scientific and societal values of this study are high. This will be of great value to the dairy cattle industry
to gain a cost-effective, sustainable dairy production with high animal welfare and minimal use of reproductive
hormones and antibiotics.
In our view, our study design corresponds to the demands of the three R's.
Replace:
Since we are investigating the embryonic gene expression and quality, which is affected by the natural
environment in the uterus, the studies would not have a similar scientific value conducted in vitro.
Reduce: We are using the smallest possible number of animals according to the sample size model. The semen
has already been collected from sires at the breeding station in Hamar.
Refine:
The procedures will be performed after a thorough learning process, and veterinarians will conduct all procedures
that involves animals. Refinement is secured at SHF as the animals are kept in a modern facility and fed normal
feed, in addition to being taken care of by well-educated staff with years of experience at SHF.
Europe. It is therefore of great concern that we have seen a reduction in non-return rate (NRR) and the national
fertility index during the last three years in Norway.
Embryo mortality (EM) is the most important cause of return to estrus and results in significant economic loss for
the dairy industry. EM may have different causes, among them genetic, nutritional and infectious. In the proposed
project, we aim to elucidate the most significant causes of EM in NR with a special focus on bulls with high or low
NRR. By investigating embryonic gene expression in relation to male genetics and male and female physiological
factors, we seek a genetic link to embryonic death in NR.
A clinical study will be performed in maximum 74 heifers in two parts at SHF, NMBU.
• 1) 12 heifers will be superovulated and inseminated with semen from bulls with either high or low NRR ,
respectively. On day -8, the embryos will be collected through embryonic lavage, morphologically quality
evaluated, frozen and later exposed to gene expression studies. If necessary, part 1 will be repeated.
• 2) 50 heifers will be followed carefully until day 42 of pregnancy to catch late embryo loss.
Repeated clinical examinations including body condition score (BCS), rectal palpation, ultrasound and sampling of
blood will be performed. Focus will be nutritional condition, hormones, pregnancy associated factors, endometritial
samples and in case of embryo loss, uterine biopsies.
The heifers will follow a normal pregnancy and calving after the studies are finished.
The heifers will live the normal life of dairy cattle with a few more examinations than usual:
1) Blood sampling.
2) Clinical examinations
3) Superovulation, insemination and collection of embryos (part 1). On the day of embryo collection, the animals will be
sedated and given epidural anesthesia.
Expected scientific and societal values of this study are high. This will be of great value to the dairy cattle industry
to gain a cost-effective, sustainable dairy production with high animal welfare and minimal use of reproductive
hormones and antibiotics.
In our view, our study design corresponds to the demands of the three R's.
Replace:
Since we are investigating the embryonic gene expression and quality, which is affected by the natural
environment in the uterus, the studies would not have a similar scientific value conducted in vitro.
Reduce: We are using the smallest possible number of animals according to the sample size model. The semen
has already been collected from sires at the breeding station in Hamar.
Refine:
The procedures will be performed after a thorough learning process, and veterinarians will conduct all procedures
that involves animals. Refinement is secured at SHF as the animals are kept in a modern facility and fed normal
feed, in addition to being taken care of by well-educated staff with years of experience at SHF.