Doctor of Philosophy / Department of Animal Sciences and Industry / Barry J. Bradford / The mechanisms behind the metabolic changes observed when transition cows are administered monensin, as well as the effects of supplementing mid-lactation cows with two commercial amino acid products were investigated. Traditionally, the effects of monensin are attributed to increased gluconeogenic precursor supply, but recent research indicated that the effects of monensin extend beyond gluconeogenic flux. Thus, the primary objectives of Experiment 1 were to determine if monensin modulates transition cow feeding behavior, ruminal pH, and/or expression of key metabolic genes. Overall, monensin decreased time between meals prepartum (126 vs. 143 ± 5.0 min; P < 0.03) with a trend appearing postpartum (81.4 vs. 88.8 ± 2.9 min; P < 0.08), which could be related to the smaller ruminal pH standard deviation during the first day cows received the lactation ration (0.31 vs. 0.26 ± 0.015; P < 0.02). Monensin also increased liver mRNA abundance of carnitine palmitoyltransferase 1a (0.15 vs. 0.10 ± 0.002 arbitrary units; P < 0.04), which corresponded to a slower rate of liver triglyceride (TG) accumulation from 7 days before calving through 7 days post calving (412 vs. 128 ± 83 mg TG/g protein over this time period; P = 0.03). No significant effects of monensin supplementation were observed on other metabolic parameters or milk production. Overall, these results confirm that the effects of monensin on transition cows extend beyond altered propionate flux. In Experiment 2, mid-lactation cows consuming a control diet containing 26% wet corn gluten feed (dry matter basis) were compared to cows consuming the same diet supplemented with lysine embedded within Ca salts of fatty acids and the isopropyl ester of 2-hydroxy-4-(methylthio) butanoic acid, a methionine precursor. This trial was conducted because the NRC (2001) model indicated a lysine deficiency prior to supplementation; however amino acid supplementation had no effects. This trial was then extended to decrease dietary CP from 17.9% to 17.1%, and further increase lysine and methionine supply in the treatment diet. No production or intake effects were observed during this period, but MUN was decreased in the treated group (10.8 vs. 12.5 ± 0.2 mg/dL; P < 0.001).

Master of Science / Department of Animal Sciences and Industry / Barry Bradford / Angiopoietin-like protein 4 (ANGPTL4) is a 55-kDa secreted glycoprotein which is an important factor for regulation of energy and lipid metabolism. Plasma ANGPTL4 has the ability to inhibit lipoprotein lipase (LPL) function by preventing it from catalyzing hydrolysis of lipoprotein triglyceride, which contributes to ANGPTL4’s ability to decrease fat storage. Furthermore, research in mice suggests that gut microbes suppress gastrointestinal ANGPTL4 production, and that decreased plasma ANGPTL4 concentrations promote fat storage. In our previous work, we found that bovine ruminal epithelial cells expressed ANGPTL4 to a greater extent than liver hepatocytes, which are usually considered the predominant source of circulating ANGPTL4. Therefore, 3 studies were conducted to evaluate the hypothesis that ruminal expression and plasma concentrations of ANGPTL4 could be influenced by alterations in ruminal fermentation. The first and second studies utilized dietary treatments intended to alter ruminal fermentability. Diets with relatively low or high forage content were fed to 12 non-lactating dairy cows (study 1) and 8 beef cattle (study 2) prior to collection of ruminal fluid and ruminal tissue samples. The results suggested that increasing the dietary concentrate decreased ruminal expression of ANGPTL4 but did not significantly alter plasma ANGPTL4 concentrations. The third study was designed to assess whether effects of diet fermentability on ruminal ANGPTL4 synthesis are mediated by changes in volatile fatty acid concentrations. In this study, 6 lactating cows were infused with acetate, propionate, or butyrate in a Latin square design. Results showed that ANGPTL4 expression was not significantly altered by volatile fatty acid infusions, but that expression was correlated with ruminal pH and total volatile fatty acid concentration. The mechanism by which ANGPTL4 regulates intracellular lipid metabolism also remains unclear. Although ANGPTL4 is known to associate with β1 and β5 integrins, it is unknown if these extracellular matrix proteins mediate the effects of ANGPTL4 in adipose tissue or muscle. The objective of the last experiment was to detect the ANGPTL4 receptor or mediator in muscle satellite cells and adipose tissue. We successfully expressed recombinant bovine ANGPTL4 with a cell free glycoprotein synthesis system. However, we did not detect the ANGPTL4–receptor complex following exposure to bovine adipose tissue explants or cultured bovine muscle satellite cells. Overall, these research projects determined that the ruminal ANGPTL4 production is influenced by fermentation, but it remains unclear whether fermentation products or direct host/microbe interactions are responsible. Finally, it will be important to identify the ANGPTL4 receptor or mediator to better understand the downstream regulatory mechanisms involved in mediating the metabolic effects of ANGPTL4.

Master of Science / Department of Animal Sciences and Industry / Joel DeRouchey / Mike Tokach / Six experiments using 3,862 pigs were conducted to evaluate effects of ractopamine HCl (RAC) feeding programs, dietary L-Carnitine and dried distillers grains with solubles (DDGS) on growth, carcass traits, loin and jowl fat quality of pigs, and energy and protein sources in nursery diets. In Exp. 1 and 2, RAC-fed pigs had greater (P<0.05) ADG, G:F and HCW compared with the control. Within RAC treatments, there were no differences in growth. Pigs fed step-up RAC had increased (P<0.01) percentage lean, fat-free lean index and loin depth but decreased (P<0.01) backfat than the control or constant treatment. In Exp. 2, pigs fed step-up RAC program had greater (P<0.05) ADG and G:F than the constant treatment. Pigs fed constant RAC had greater (P=0.002) carcass yield than controls. There were no overall differences in other carcass traits among treatments. In Exp. 3, dietary L-Carnitine improved (P<0.02) ADG and final BW. A DDGS × L-Carnitine interaction (quadratic, P<0.01) was observed for G:F. Pigs not fed DDGS had similar G:F, but in DDGS diets pigs fed 50 ppm L-Carnitine had worse G:F than those fed 100 ppm. Pigs fed L-Carnitine had greater (P<0.02) HCW compared with those not fed L-Carnitine. Increasing L-Carnitine up to 100 ppm increased HCW (quadratic, P<0.03) and backfat (quadratic, P<0.04), with the maximum response at 50 ppm dietary L-Carnitine. Increasing L-Carnitine increased (linear, P<0.04) purge loss of loin. Feeding DDGS increased (P<0.001) linoleic acid and iodine value of jowl fat compared with feeding no DDGS. However, feeding L-Carnitine did not change jowl fatty acid composition. In Exp. 4, 5 and 6, nursery pigs fed choice white grease (CWG) had improved (P<0.02) G:F than pigs fed a control diet or an alcohol based energy source. Also, pigs fed CWG had greater (P<0.04) ADG in Exp. 4 and 6 and had reduced (P<0.01) ADFI in Exp. 5. The alcohol based energy source improved (P<0.04) ADG and ADFI with no change in G:F in Exp. 4; but did not affect growth in Exp. 5 and 6. In Exp. 6, pigs fed AV-E Digest had equal performance as nursery pigs fed other specialty proteins.

Master of Science / Department of Human Nutrition / Tonatiuh Melgarejo / Late-lactation Holstein cows (n=9/treatment) were used to evaluate effects of continuous adipose tissue TNFα administration on glucose and fatty acid (FA) metabolism. Cows were blocked by feed intake and milk yield and randomly assigned within block to control or TNFα treatments. Treatments (4 mL saline or 14 μg/kg TNFα in 4 mL saline) were infused continuously over 7 d via 2 osmotic pumps in the adipose layer in the tailhead region. Plasma, milk samples, milk yield, and dry matter intake (DMI) data were collected daily. On d 7, pumps were removed and liver and contralateral tailhead adipose biopsies were collected. Results were modeled with fixed effect of treatment and random effect of block; P values > 0.10 were considered non-significant. TNFα did not alter liver TNFα mRNA abundance, plasma TNFα, IL-4, IL-6, or interferon-γ concentrations, DMI, or rectal temperature. Milk fat and lactose concentrations decreased with TNFα (P < 0.05), but milk yield was unchanged and treatments did not alter the proportion of short vs. long-chain FA in milk on d 7. Treatments did not alter plasma NEFA concentration, liver triglyceride content, or adipose mRNA abundance for hormone-sensitive lipase or perilipin. Plasma glucose turnover rate, as measured by disappearance of U-13C-glucose bolus, was not altered by treatment, nor was liver mRNA abundance for phosphoenolpyruvate carboxykinase or pyruvate carboxylase. However, TNFα tended to decrease adipose TNFα mRNA abundance (P=0.09) and increase liver IL-10 mRNA abundance (P=0.05) compared to controls. Messenger RNA expression of IL-10 in adipose and IL-37 in liver tissue increased significantly in cows treated with TNFα (Figure 1; P = .02 adipose; P < 0.05 liver). This TNFα delivery protocol may have allowed for an adaptive anti-inflammatory response to suppress systemic inflammation, which may account for the lack of metabolic responses compared with previous responses to daily subcutaneous TNFα injections.

Master of Science / Department of Human Nutrition / Koushik Adhikari / Three cuts of steak (strip, chuck-eye and top blade) of two United States Department of Agriculture grades (choice and select) underwent seasoning and tenderization treatments to study whether flavor and texture quality could be enhanced within cut and grade of steak. Treatments included: 1) seasoning alone, 2) a combination of seasoning + bromelain (enzymatic tenderizer), or 3) control (no seasoning and/or bromelain). The seasoning included: kosher salt, black pepper, onion powder, garlic powder, cumin, and ground oregano. All of the steaks were cooked to an internal temperature of 71° C (medium doneness). Six trained descriptive panelists evaluated the samples. The results of this study indicate that it may be possible to improve eating quality of choice and select chuck-eye and choice top blade to be more similar to strip steaks of the same USDA grade. Both treatments increased flavor and texture attributes in these samples that have been shown to have an impact on liking scores. Choice chuck-eye samples had decreased bloody/serumy and metallic scores and increased umami and initial flavor impact with both treatments. Both treatments increased brown/roasted flavor in select chuck-eyes. Tenderness, fat-like and umami were increased with the seasoning + bromelain treatment in select chuck-eyes. Choice top blade steaks with seasoning alone had increased umami flavor. Both treatments impacted attributes (fat-like, umami and sour) of the select strip steak that differed from choice strip steaks. The next step to this research is to investigate whether consumer liking scores are consistent with conclusions made from descriptive analysis results. Overall, these treatments could be a valuable tool for beef retailers.

Doctor of Philosophy / Department of Human Nutrition / Mark D. Haub / Background: Dietary fiber has been shown to help improve several metabolic disorders including obesity and type II diabetes. However, the mechanism by which this occurs is poorly understood. Purpose: This study was designed to compare the effects of energy restriction and dietary fiber and subsequent production of short chain fatty acids on body composition, biomarkers of health, and hepatic and myocellular expression of key regulators of lipid metabolism Methods: Crossbred gilts (n=17) were randomly assigned to either a control (CON), high fiber (HF) or energy restricted (ER) diet for 42 days. Gilts on the CON and HF diets were fed ad libitum. The ER Gilts were pair fed HF gilts and matched for body weight gain. Blood samples were collected and glucose, insulin, triglycerides, non-esterified fatty acids and short chain fatty acids (SCFA) concentrations were measured. Liver and muscle tissue were biopsied and expression of peroxisome proliferator-activated receptor gama (PGC-1α) and carnitine palmitoyltransferase 1 (CPT1) were determined via RT-PCR. Results: HF gilts had significantly higher plasma TG and lower NEFA concentrations when compared to the CON and ER. The HF diet elicited a significant increase in all plasma SCFA concentrations. No differences in fold change of myocyte CPT1 and PGC-1α mRNA expression were found while they tended to be lower in hepatic samples of the HF gilts. HF gilts also had a lower (P < 0.05) back fat thickness when compared to the ER even though energy intakes were similar. Minimal changes were observed in fasting glucose and insulin as a result of diet. Conclusions: Gilts consuming a diet high in dietary fiber (DF) significantly altered their plasma lipid profiles independently to that of energy restriction and body weight and appears to be a result of plasma SCFA concentration. DF and/or SCFA appear to have minimal affects on CPT1 and PGC-1α in the liver and muscle of gilts.

Master of Science / Department of Animal Sciences and Industry / Daniel W. Moser / Among working dogs, the role of a guide dog ranks as one of the most noble and useful occupations and thus was recognized early as a category of working dogs worthy of focused research. Behavior issues top the list of most common reasons for rejecting dogs from working as guides. The objective of this study was to estimate genetic parameters for each of the 101 questions and 12 subscale factors measured by the Canine Behavioral Assessment and Research Questionnaire (C-BARQ). The C-BARQ is a standardized questionnaire that contains seven behavioral categories: training and obedience, aggression, fear and anxiety, separation-related behavior, excitability, attachment and attention-seeking, and a miscellaneous category. These categories and questions allow the evaluator to describe any dog's behavior. For this study, questionnaire responses were obtained on 3,149 and 3,348 Labrador Retrievers (LR) from Guiding Eyes for the Blind (GEB) and 989 and 1,187 Labrador Retrievers, 608 and 692 Golden Retrievers (GR), and 966 and 1,348 German Shepherd Dogs (GSD) from The Seeing Eye, Inc. (TSE) at 6- and 12-months of age, respectively. The estimates of heritability and standard errors from TSE dogs indicate that there is much genetic variation that could be exploited in selection against "Familiar dog-directed aggression/fear" (0.27 ± 0.12) of GR at 6-months, "Chasing" (0.22 ± 0.10) of GR at 6-months, and "Nonsocial fear" (0.27 ± 0.09) of GR at 12-months or in selection for improved "Trainability" of LR (0.46 ± 0.07), GSD (0.47 ± 0.07), and GR (0.20 ± 0.08) at 12-months. In general, the remaining factors and most of the 101 questions were found to be lowly heritable (< 0.10). These estimates are useful to understand more about the nature of behavioral traits leading to the production of successful working guides.

Master of Science / Department of Animal Sciences and Industry / Terry Houser / Crossbred yearling steers (n = 144 initial BW 367 ± 18.46 kg) were randomly allotted by BW to a randomized complete block design with a 2x3 factorial treatment arrangement to 1) assess the impact of supplementing dried distiller grain with solubles (DDGS) while grazing late season forage for 90 d and 2) the impact of a short feeding period on animal performance, carcass characteristics and meat quality traits. Treatments consisted of DDGS supplementation during grazing (0 or 1% of BW as DDGS; DM basis) and finishing days on feed (DOF;75, 100, 125). During grazing supplemented cattle had greater (P < 0.01) ADG than un-supplemented cattle but un-supplemented cattle had greater ADG than supplemented cattle during the finishing period. There were no differences between grazing treatments for DMI (P = 0.91) during the finishing period. Supplemented cattle had decreased (P = 0.02) G:F during the finishing period compared to un-supplemented cattle. Supplemented cattle had heavier (P < 0.01) HCW and larger (P = 0.02) LM area than un-supplemented cattle. Increasing DOF linearly increased (P ≤ 0.03) HCW, 12th rib fat thickness, LM area and USDA marbling score. No differences were observed for USDA yield grade. Increasing DOF decreased (Linear; P < 0.01) carcass protein %, moisture %, and increased (Linear; P < 0.05) carcass fat %. Increasing DOF increased (Quadratic; P = 0.01) L* values, while decreasing (Quadratic; P < 0.01) a* and b* values for external fat color. No differences were observed with respect to the percentages of any fatty acids for any treatment. Increased (P = 0.01) sensory off-flavors were present at 100 DOF when compared to 125 DOF. No other differences among treatments were observed for any sensory traits, instrumental tenderness, lean color or fatty acid profile for any treatment. In conclusion, supplementing cattle with 1 % DDGS during grazing altered grazing and feedlot performance as well as impacted carcass characteristics. In addition, utilizing a shortened feeding period had minimal effects on meat quality traits, but increasing DOF resulted in a greater amount of whiter external fat.

Master of Science / Department of Animal Sciences and Industry / John Michael Gonzalez / The objective of this body of work was to examine effects of growth-promoting technologies (GP) on Longissimus lumborum meat tenderness, focusing on alterations of muscle fiber cross-sectional area (CSA) and collagen solubility. Two studies were conducted and analyzed as randomized complete block designs with repeated measures with GP and day of postmortem aging (DOA) as main effects. Treatments consisted of: a control (CON), implant only (IMP), and implant and [beta]-adrenergic agonist (COMBO). The [beta]-adrenergic agonist utilized for the first was zilpaterol hydrochloride, while the second study examined ractopamine hydrochloride. Objective tenderness of strip loin steaks was measured through Warner-Bratzler shear force (WBSF) after 2 (study 2) or 3 (study 1), 7, 14, 21, or 35 d of postmortem aging. Muscle fiber CSA and collagen solubility were analyzed via immunohistochemistry and hydroxyproline content, respectively. For the first study there was a treatment × DOA interaction (P < 0.01) for WBSF. Compared to CON steaks, IMP steaks had greater (P = 0.01) WBSF on d 3, but were similar (P = 0.21) by d 14. The COMBO steaks remained less tender at all-time points (P < 0.04) except d 21 (P = 0.13) when compared to the CON. Growth-promoting treatment increased the CSA of all three muscle fiber types (P < 0.01), but had no effect on collagen solubility measures (P > 0.21). The second study observed no treatment × DOA interaction (P = 0.54) for WBSF, but GP increased (P < 0.01) WBSF across all DOA. Growth-promoting treatment tended to increase the CSA of type I and IIX fibers (P < 0.10), and increased (P < 0.01) type IIA fiber CSA. In agreement with the first study, there was no treatment × DOA interaction or treatment effect on collagen solubility (P > 0.75). The addition of GP to feedlot heifer production increased WBSF of strip loin steaks and fiber CSA, but did not impact collagen characteristics.

Master of Science / Animal Sciences and Industry / Micheal J. Brouk / Study 1 was performed to assess the effect of an evaporative cooling system (ECS) on core body temperature (CBT) and lying times in lactating dairy cows. Respiration rates and rear udder temperatures (T[subscript u]) were also measured. Trial 1 contained 3 environmental treatments while trial 2 contained 2 environmental treatments. Treatments were: OFF (Cyclone fans and fog shut off), FAN (Cyclone fans only, no fog), and FANFOG (Cyclone fans and fog on) and cows exposed to these 3 environments were housed in a bedded pack barn (PACK) equipped with an ECS or a tie-stall barn (TIE). TIE and PACK cows moved between barns every 8 h for milking and both groups moved opposite of each other. Ambient, barn temperature and relative humidity (RH) measurements in addition to vaginal temperatures and lying times were recorded by sensors which took measurements at 1 min intervals. Respiration rates (BPM), for PACK cows during FANFOG were reduced (P < 0.05) when compared to TIE (53 ± 2.0 vs 64 ± 2.0, respectively) in trial 1. Similar results were found in trial 2. Rear udder temperature was measured and found to be decreased (P < 0.05) in PACK cows while housed under FANFOG vs TIE in trial 1. These results could not be repeated in trial 2 because of greater ambient temperatures. Core body temperature (CBT) was reduced during each trial as shown by less time spent above 39.0°C during FANFOG. During trial 2, PACK spent 5.7 and 8.5 h/d less over a CBT of 39.0°C compared to TIE cows. Total daily lying time was tracked and found to increase for cows exposed to the ECS during PACK but no difference between PACK and TIE. In study 2, the same ECS was used but its effects on nonlactating dairy cows were studied. There was a treatment by h interaction for vaginal temperature showing the greatest effects during the afternoon h where FANFOG had numerically decreased CBT vs FAN. FANFOG cows spent reduced time over a CBT of 39.0°C and greater time < 38.0°C. FANFOG cows also had increased lying times of 1.7 h/d compared to FAN.