Browsing by Subject "Milk"
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Item Effects of betaGRO© on the performance of dairy cows and calves(2016-06) Rosales Gallardo, AngelSeven individual studies were conducted to assess the effects of betaGRO©, a further processed spray-dried porcine plasma (SDPP) product, on insulin-like growth factor I (IGF-I), and performance of dairy cows and calves. We hypothesized that betaBRO© can activate esophageal receptor that might be responsible for biological responses. Results herein indicate that betaGRO© had no major effects on dairy cows when fed as a top-dress supplement, suggesting that the product might need to reach the lower gut to exert an impact. In order to evaluate this new hypothesis, betaGRO© was fed to neonatal calves and it was also infused into the abomasum of rumen cannulated cows. However, neither of these experiments detected a significant change on concentration of IGF-I or in the performance of the animals. Only CD11b was affected by betaGRO© which indirectly supports theories prompting modulation of immune response by SDPP products.Item Epidemiological assessment of hyperketonemia in dairy herds: implications for disease diagnosis and control(2021-06) Rodriguez, ZelmarMetabolic disorders are a frequent problem in the transition period of dairy cows. During this period, higher concentrations of circulating ketone bodies, known as hyperketonemia (HYK), indicate that the cow is utilizing body reserves to fulfill the energy requirement of her new physiological state. Hyperketonemia has been associated with other metabolic and infectious diseases during early lactation, decreased milk production, increased likelihood of herd removal, and impaired reproductive performance. However, the influence of the energy balance during the late dry period on the development of HYK has not been fully quantified. Similarly, the role that milk yield in early lactation plays in hyperketonemic cows due to the importance that the lactogenesis process has in the energy balance needs to be explored. In terms of diagnostics, it has been reported a differential effect of HYK in multiple health outcomes and production according to the moment of disease diagnosis. However, these effects have been evaluated only in the short term. Understanding the effect of HYK in the entire lactation according to the moment of disease diagnosis is needed to determine the optimum timeframe for diagnosis. Consequently, the goal of this dissertation is to better understand the epidemiology of HYK to guide the implementation of optimal decisions to control and diagnose the occurrence of the disease. Our results suggest that a) cows with loss of BCS over 0.5 points during the late dry period have the peak of BHB concentration at day 7 of lactation and have a higher risk of HYK than cows without variations in BCS during the late dry period. b) The impact of HYK on health and productivity varied according to the moment of diagnosis. HYK diagnosed on the first week of lactation was associated with lower milk production and pregnancy rate, and with a higher risk of early removal from the herd than non-hyperketonemic cows. c) Furthermore, it was observed that early milk yield plays a role in the association of HYK with reproductive performance. Among low producers, hyperketonemic cows were less likely to become pregnant. Conversely, reproductive performance was similar among mid- and high-yielding cows, independent of HYK status. In conclusion, to prevent HYK in early lactation, management strategies in the prepartum period should focus on preventing loss of BCS over 0.5 points. After calving, the diagnosis of HYK should be performed at the first week of lactation, and especially targeting cows with lower milk yield. Although more studies need to be performed to improve HYK control, this dissertation provides tools to prevent and control the disease in dairies, with straightforward farm-applicable strategies.Item Factors Affecting Flavor Quality of Bovine Milk and Dairy Products(2016-12) Potts, DavidMilk is an important food staple consumed around the world. Fluid milk is consumed as a standalone beverage, used in meal preparation, serves as the fundamental ingredient for fermented foods (yogurt, kefir, cheese, etc.), and is used for processed dairy products such as butter, ice cream, coffee creamer, etc. Indeed, it is this very versatility that necessitates that milk have the highest possible flavor quality to maintain and expand market share of dairy products, as well as provide nutritive benefits and better hedonics for consumers. In this work, two individual studies were undertaken to better understand drivers of dairy quality as a result of volatile and nonvolatile sensory stimuli respectively, and both were directly related to addressing current needs in the dairy industry. The first study focused on the elucidation of potential causes of a documented off-flavor defect, spontaneous oxidized flavor (SOF) in milk. The second study aimed to provide an improved understanding of the contribution of nonvolatile small-molecular weight compounds on textural attributes as related to creaminess perception in dairy products. For the first study, the principal objective was to identify the causative off-flavor compounds in SOF milk. Comparative aroma analysis between a reported SOF milk and clean milk sample without noted off-flavors (control) were investigated using various volatile analytical techniques, including solvent extraction, solvent assisted flavor evaporation (S.A.F.E.), and gas chromatography-olfactometry/mass spectrometry (GC-O/MS), utilizing the OSME method for aroma discrimination. Key differences in the aroma profiles of the off-flavored milk were found in several very strongly rated “green, musty” terpenoid compounds that were completely absent from the control. These compounds were positively identified as endo-borneol, 2-methylisoborneol, and α-terpineol. After quantification studies, the impact of these compounds was validated using aroma recombination analyses. A degree of difference sensory test incorporated a control clean milk (same as reference), a clean milk spiked with day 0 levels of the terpenoid off-flavor compounds (endo-borneol 0.95 µg/L; 2-methylisoborneol 0.0037 µg/L; α-terpineol 0.84 µg/L), and a clean milk spiked with day 14 levels of the same compounds (endo-borneol 0.20 µg/L; 2-methylisoborneol 0.017 µg/L; α-terpineol 0.62 µg/L). The control milk was rated 0.75, the day 0 milk rated 1.67, and the day 14 milk rated 2.0 (α=0.05, critical difference value=1.0897), showing that the addition of the terpenoid “musty” compounds resulted in a significantly different flavor profile when compared to a reference clean milk. Panelists described similar “unclean” perceptions as were found in the preliminary tasting of the original milk samples. As a result, it was confirmed that the identified terpenoid compounds were responsible for flavor defects observed in the initial off-flavor milk. While the milk screened for this study was identified as ‘SOF’ in nature, more research would be needed to verify that this was indicative of SOF or simply another off-flavor issue. Regardless, these results illustrated a benefit to the dairy industry to conduct more directed off-flavor analyses and determine the root causes of product off-flavors on a per sample basis. The aim of the second study was to provide greater understanding of molecules that contribute to texture attributes associated with creaminess perception in dairy products. Heavy whipping cream was selected from several dairy product extracts as a characteristically ‘creamy’ product. Optimized food grade solvent extraction, HPLC multidimensional fractionation, and descriptive analysis using a five-term sensory lexicon and references were employed to identify fractions of interest with the strongest textural attributes. UPLC/MS/MS analyses and NMR afforded the positive identification of five compounds associated with textural attributes, falling into three categories: vitamin complex (orotic acid, pantothenic acid) hippuric acid (hippuric acid, 2-methylhippuric acid), and sulfate compounds (p-cresol sulfate). Quantitative measurements of the individual compounds were undertaken to assess their presence across a variety of nonfat, reduced fat, and full fat dairy products, and concentrations obtained from skim milk and whole milk were used for further recombination sensory experiments. A control skim milk was compared with a skim milk spiked with the five texture-active compounds at levels found in whole milk (orotic acid 120 mg/kg; pantothenic acid 1.3 mg/kg; hippuric acid 1.6 mg/kg; 2-methylhippuric acid 300 mg/kg; p-cresol sulfate 9.5 mg/kg). The 2-AFC sensory evaluation tests indicated the spiked skim milk had a significantly “creamier, fuller bodied flavor” when compared with the control skim milk (p=1/2, n=20, α=0.01). This verified the sensory relevance of the identified compounds, indicating the contribution of these compounds to creaminess perception. None of these five compounds have been previously reported in literature to exhibit textural effects, nor effects on creaminess quality in dairy. In summary, elucidation of the objectionable flavors present in a purported SOF whole milk sample indicated the cause of off-flavor was from a microbial source or a flavor ‘taint’ not caused by spontaneous oxidation. This indicated the dairy industry would benefit from a more bottom-up approach in identifying responsible objectionable flavor compounds to make informed decisions about minimizing off-flavors in fluid milk. The second study provided novel understanding of compounds that contribute to textural attributes and creaminess perception. Identification of these compounds provides an improved basis for product developers to positively influence creamy texture and target creamy quality enhancement in dairy products. In acknowledging the role that texture compounds play alongside the larger picture of creaminess obtained through previous research, developers may create high-quality nonfat, reduced fat, and full fat dairy products for a variety of markets, consumers, and purposes.Item Flavor changes in stored extended shelf-life flavored milks(2014-07) Strohman, Deena RuthanneRaw, reduced-fat milk with added strawberry flavor and color, gums, sucrose, and vitamins was pasteurized at 89°C for 13 seconds and then stored for 1 to 4 weeks at 4-7°C. Gas chromatography-mass spectrometry was used to quantify changes in aroma compounds during storage. A trained descriptive panel was used to monitor sensory changes (or preferences) during storage. The quantity of strawberry aroma compounds remained constant during storage, but our trained descriptive panel found that strawberry flavor decreased. Milk with strawberry flavor added just prior to tasting was described as being sweeter, having more strawberry notes, and having less other off-flavors than milk with strawberry flavor added before pasteurization.Item The perfect food and the filth disease: milk, typhoid fever, and the science of state medicine in Victorian Britain, 1850-1900(2011-06) Steere-Williams, JacobThis dissertation examines the complex ways that public health practices developed in Victorian Britain, particularly how standards of scientific knowledge interacted with social and cultural ideas. My central argument is that cultural conceptions of milk as a wholesome, healthful food were intimately tied to and in some ways challenged by the rapidly developing sciences of epidemiology and analytical chemistry, creating a framework for public health policies. This was most apparent at the central level through the work of the Medical Department of the Local Government Board and the Government Chemical Laboratory of the Excise Department, and locally throughout Britain through the work of local Medical Officers of Health and Analytical Chemists. I demonstrate that epidemiologists, chemists, and veterinarians, were the scientific translators of deeply embedded social concerns about purity and progress. These disciplines were largely framed by interactions with different facets of the public; scientific knowledge about milk and disease was reified by milk producers and milk consumers who stressed the importance of purity as representative of cultural progress and British superiority. Milk was not a static cultural or material product, and its cultural meaning and material use changed dramatically throughout the period I investigate. Such analysis sheds historical light on contemporary problems about food safety and reminds us that consumption practices are always embedded within cultural assumptions about nation, personhood, science, and progress.