Solano-Suárez, Karol Gilberto, authorPinedo, Pablo J., advisorBruemmer, Jason, committee memberRoman-Muniz, Noa, committee memberBohn, Andrea, committee member2020-01-132020-01-132019https://hdl.handle.net/10217/199835The transition period is acknowledged as a time of increased stress and risk to develop infectious, non-infectious, and metabolic diseases due to fetal growth and the onset of lactogenesis. In the past decades, antimicrobial resistance in animals and humans has become an environmental and public health concern, and the restrictions on the use of conventional drugs in organic certified dairy farms encourage the research on novel approaches for the prevention and treatment of infectious diseases in dairy systems. Natural alternatives and biomolecular technologies have been studied to diminish the impact of diseases during the transition period for conventional and organic certified dairy, and a couple of them will be discussed in this thesis. Chapter 1 comprehend a literature review on transition period elucidating the complex and multifactorial chain of events that lead to make the cow susceptible to develop metabolic and infectious diseases. Metabolic disorders such as negative energy balance and hypocalcemia are connected with the excessive inflammation and cellular immunosuppression occurring around calving. Then, a brief description of other related diseases and new strategies for prevention and treatment of them is discussed. Chapter 2 describes an experiment using an immunomodulator based on Mycobacterium cell wall fraction (MCWF). We hypothesized that the subcutaneous administration of MCWF within the two weeks before calving and within 24 hours after calving could generate a nonspecific cellular immune response capable of reducing the risk of peripartal infectious diseases in dairy cows. Therefore, our objective was to evaluate the effect of a commercial immunomodulator based on MCWF (Amplimune®, NovaVive Inc., Belleville, Canada) on presentation of peripartal diseases and reproductive performance of Holstein cows, assessing cellular immune response and metabolic status. The presentation of clinical metritis, clinical mastitis, and pyometra in MCWF cows were significantly lower compared to CON cows, although the presentation of respiratory disease before 28 days in milk was significantly higher compared to CON cows. The overall reproductive performance was significantly improved in MCWF cows compared to CON cows. Future research at different physiological stages and using different doses and routes of administration is encouraged. Chapter 3 describes an experiment using a pulsed alternating wavelength system (PAWS). We hypothesized that PAWS could elicit a positive hormonal and metabolic response that might reduce presentation of dystocia, as well as the imbalances and stress around calving, improving peripartal health and subsequent performance in transition dairy cows. Hence, our objective was to evaluate the effect of PAWS on dystocia presentation, peripartal health, activity, and serum levels of melatonin (MEL), serotonin (5-HT), prolactin (PRL), somatotropin (BST), calcium, nonesterified fatty acids (NEFA) and β-hydroxybutyrate (BHB) of organic certified Holstein cows. Cows exposed to PAWS reduced the presentation of dystocia and modify NEFA serum levels within 3 days after calving. However, results of melatonin were not available by the time of this writing to clarify the effect of PAWS on these outcomes.born digitalmasters thesesengCopyright and other restrictions may apply. User is responsible for compliance with all applicable laws. For information about copyright law, please see https://libguides.colostate.edu/copyright.immunomodulatorperipartal healthtransition periodMycobacterium cell wall fractiondairy cow cattlepulsed alternating wavelength systemText