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ReproDairy Lab
Research area: Applied mechanisms to enhance health, production, and reproduction.
Effect of omega-3 diet supplementation on milk production and embryo development of high producing lactating Holstein cows
It is estimated that the global population will reach approximately 9.7 billion people by 2050, while healthier food consumption and global sustainability awareness will continue to increase. Dairy cattle milk continues to have an important role in the human diet and could be used to address healthier food, such as those enriched in Omega-3 (OMG3) fatty acids.
The objective of this study is to evaluate the effect of diet supplementation with OMG3 fatty acids on embryo development and milk composition of lactating Holstein dairy cows. Our hypothesis is that cows supplemented with OMG3 will have greater embryo development and concentration of OMG3 in milk. In order to test this, lactating Holstein cows will be equally divided into a control diet group and a treated group with a diet enriched in OMG3. The supplementation will be given from the week of calving until approximately 130 days in milk or until reaching 60 days of gestation. Eggs (oocyte), blood and milk samples will be collected throughout the experiment to assess the fatty acid profile and the concentration of hormones related to pregnancy. Moreover, embryo size will be measured with ultrasound. We expect that this study will illustrate the reasons for the benefits of using omega-3 in dairy cattle reproduction while producing milk enriched in OMG3 for human consumption.
Needle-free injection system for luteolysis in lactating dairy cows
Reproductive efficiency is key to the success of dairy farms. Cows getting pregnant at the right time generate more calves and spend more time at the high production stage of the milking curve. This translates to increased profitability of dairy operations.
Estrous cycle synchronization is widely adopted as a strategy to obtain high reproductive efficiency. The simplest hormonal strategies rely only on prostaglandin F2a (PGF) treatments or its analogs to regress the corpus luteum (CL) and allow spontaneous estrus expression and ovulation. The administration of these products may be performed via intramuscular (IM), subcutaneous, intravenous, vaginal, or vulvar. Nevertheless, i.m. administration is the most common. In that sense, compliance plays a critical role in these treatments. Moreover, the use of needle-free or needle-less systems, for i.m. administrations of vaccines, has been used in humans and swine, among other species. The Needle-free injection system uses compressed air to push drugs through the skin.
We will test the effectiveness of a needle-free injection system to deliver intramuscular drugs in dairy cattle. In this particular study, we will administer a PGF analog so that we can evaluate the half-life of the drug after administration and its effectiveness in regressing the CL. This project will help to reduce work injuries and to decrease disease transmission when needles are used.
Research area: Dairy genetic selection and reproduction
Novel Indirect Traits for Early Selection of High Fertility in
US Holstein Cattle
Selection for fertility can be challenging since pregnancy rate is lowly heritable, expensive to achieve, measured later in life, and is a binary trait. In contrast, indicator traits are used to obtain an indirect genetic improvement in economically relevant traits. They should be highly heritable, ideally, have a low cost, and be easy to measure early in life. Anogenital distance (AGD, distance from center of the anus to the clitoris) has been recently proposed as a proxy to select animals with better fertility.
In the proposed three phases of this study, we will test the hypothesis that AGD can be measured in calves and will reflect the length of the distance when the animal becomes heifer at breeding age and primiparous lactating cow and is (genetically) negatively correlated with heifer and cow fertility. Phase 1 will use Holstein heifers during breeding age, from which, 2/3 will be used during phase 2 as primiparous cows. These phases aim to validate the phenotypic correlation and test the genomic association of AGD, Anti-Mullerian-hormone, and antral follicle count with reproductive traits such as pregnancy rate, cow conception, and heifer conception rates; and to estimate the heritability of AGD. Phase 3 will use newborn female Holstein calves until breeding age to finally estimate the correlation among newborn-calve-AGD, heifer-AGD, and primiparous-cow-AGD. The results from this research have the potential to provide a new culling tool for farmers and to provide novel indirect traits for early selection of high reproduction in lactating Holstein cows.
Research area: Physiologic mechanisms controlling follicle selection in cattle
Role of LH/FSH pulses and transcriptomics for a new model of follicle selection in cattle
Humans, horses, and cattle select and ovulate a single egg from many in the ovaries. We will investigate the mechanisms controlling this selection process. Thus, we will test a new follicle selection model by evaluating the acute effect of reproductive hormones on the transcriptome of the cells surrounding the eggs. Moreover, we will assess the impact of hormonal pulses on double ovulation in lactating dairy cows, which is considered undesired in the industry.
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