Browsing by Subject "Feeding Behavior"
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Item A Cross-Cultural Examination of Parenting Style and Feeding Practi(2011-02-01T19:34:27Z) Hinton, Leilani Kaulana; Holub, ShaylaChildhood obesity is an issue of great concern to health professionals in the United States. Past research has emphasized the role parenting styles (e.g., the global parenting environment) and parents? practices (e.g., specific parent behaviors) play in shaping childhood weight status. This study is the first to examine the associations of parenting style, feeding practices and children?s self-regulation of food intake in a South Asian population. Self-report data was collected from a community sample of South Asian parents with children between the ages of 3 to 9 years old (N = 54). Participants were 75% mothers and 25% fathers. Feeding practices were compared between South Asian mothers and data from a control group that was collected from an ongoing study. Survey items measured parenting style dimensions of warmth, psychological control, and behavioral control. Parents? controlling feeding practices of pressure, restriction for health and restriction for weight were also assessed. Self-regulation was measured by parent?s report of child?s external eating and food responsiveness, as well as satiety responsiveness. Results of this study revealed South Asian mothers used more pressure in feeding than Caucasian mothers, but did not use more restriction. Acculturation was not associated with parenting style dimensions or feeding practices, but was associated with external eating. The parenting style dimension of psychological control was positively correlated with restriction for health and pressure. Psychological control and restriction for health were associated with external eating, while these variables and restriction for weight were associated with food responsiveness. Regression analyses suggest that restriction for health was the best predictor for both of these variables. Restriction for weight was related to satiety responsiveness, but this variable was not significant after controlling for child weight status. The results of this study are consistent with previous research on feeding practices and self-regulation. Parenting interventions targeting child obesity should consider teaching parents to employ less controlling feeding practices, as these methods were associated with lower self-regulation ability in children.Item Effects of Residual Feed Intake Classification on Feed Efficiency, Feeding Behavior, Carcass Traits, and Net Revenue in Angus-Based Composite Steers(2012-02-14) Walter, JoelThe objectives of this study were to evaluate the effects of residual feed intake (RFI) classification on performance, feed efficiency, feeding behavior and carcass traits, and to determine the relative importance of individual performance and carcass measurements on between-animal variation in net revenue of feedlot steers. Performance, feed intake and feeding behavior traits were measured in 508 Angus-based composite steers, using the GrowSafe feed-intake measurement system, while fed a high-grain diet for 70 days. Residual feed intake (RFI) was computed as actual minus expected dry matter intake (DMI) derived from regression of DMI on average daily gain (ADG) and mid-test BW0.75, and steers classified into low (n = 150), medium (n = 200) and high (n = 158) RFI groups. Following the feed-intake measurement periods, steers were fed the same diet in group pens and harvested at an average backfat thickness of 1.14 cm. Net revenue (NR) was calculated as carcass value minus feeder calf, yardage, and feed costs using 3-year average prices. Feed cost was based on actual feed consumed during the feed-intake measurement periods, and model-predicted intake adjusted for RFI during the group-feeding periods. Steers with low RFI had $48/hd lower (P < 0.0001) feed cost, $16/hd numerically higher (P = 0.29) carcass value, and $62/hd more favorable (P < 0.0001) net revenue compared to their high-RFI counterparts. Net revenue was correlated with carcass weight, marbling score, yield grade, DMI, ADG, RFI and G:F ratio where animals that consumed more feed, had higher rates of gain and were more efficient had more favorable net returns. Models predicting net revenue from performance, carcass quality, and feed efficiency traits accounted for 77% of the between-animal variation in NR. In the base model, that included all traits performance, carcass quality and feed efficiency traits explained 28, 14 and 35%, respectively, of the variation in NR. Results from this study indicate that between-animal variation in net revenue was impacted to a great extent by performance and feed efficiency, rather than carcass quality traits, in Angus-based composite steers based on average 3-year pricing scenarios.Item Electrophysiological and Behavioral Mechanisms of Caenorhabditis Elegans Feeding(2004-12-15) Shtonda, Boris Borisovich; Avery, LeonThe nematode (roundworm) Caenorhabditis elegans lives in soil and eats bacteria. Its feeding organ is a neuromuscular pump called the pharynx. First, I developed a voltage clamp preparation for the pharynx and recorded native ionic current in the pharyngeal muscle. I showed that a T-type Ca channel CCA-1, an L-type Ca channel EGL-19 and a potassium channel EXP-2 shape pharyngeal action potentials. CCA-1 works in the pharyngeal muscle to boost its response to neurotransmission from the MC pharyngeal neuron. Next, EXP-2 is not an inward rectifier in the pharynx; it generates large currents upon hyperpolarization and has nearly linear voltage dependence. Finally, the pharynx adapts to the loss of MC excitatory inputs by raising its resting membrane potential, which makes it more excitable. Second, I studied food seeking and food preference behaviors in C.elegans. In the laboratory, C.elegans is routinely kept on plates seeded with E.coli, and it is not known how worms behave in an environment where diverse food is available. I identified additional food sources, such as Bacillus megaterium, Comamonas sp., and Bacillus simplex, and showed that bacterial food varies in quality. C.elegans hunts for the food of higher quality, the one that better supports growth. This seeking activity is further enhanced in animals that have already experienced good food. Next, the food regulates C.elegans locomotion, particularly the equilibrium between two locomotion modes, known as roaming and dwelling. On good food, dwelling is more common, on poor food, roaming is predominant. The normal balance between these states is essential for the food seeking behavior. In ttx-3 and osm-6 mutants the food-dependent equilibrium between locomotion states is impaired: worms tend to spend less time roaming on poor food. ttx-3 defects are partially reproduced by laser ablation of AIY interneurons, suggesting that AIY functions to inhibit the roaming-to-dwelling transition and to extend food-seeking periods. On the other hand, tax-6 mutants show increased roaming even on high quality food. tax-6, osm-6 and ttx-3 mutants are defective in food choice behavior. C.elegans may serve as a new system to uncover mechanisms that enable animals to find high quality food in diverse environments.Item Examining Mechanisms Contributing to the Biological Variation of Residual Feed Intake in Growing Heifers and Bulls and in Mid-Gestation Females(2012-10-19) Hafla, AimeeThe objectives of this study were to characterize residual feed intake (RFI) in growing bulls and heifers and in mid-gestation females to examine relationships with performance, body composition, feeding behavior, digestibility (DMD) and heart rate (HR) and evaluate the impact of RFI on bull fertility and cow forage utilization. Additionally, use of the n-alkane method to predict individual animal variations in intake was investigated. To accomplish these objectives, multiple RFI studies were conducted. In all studies RFI was computed as the difference between actual and expected DMI from linear regression of DMI on mid-test metabolic BW and ADG. To evaluate phenotypic relationships between feed efficiency, scrotal circumference (SC) and semen-quality an experiment was conducted with yearling bulls (N=204). Residual feed intake was not correlated with BW and ADG, but was positively associated with 12th-rib back fat (BF) such that the more efficient bulls were leaner. Bulls with low RFI had similar SC and progressive motility of sperm compared to high-RFI bulls. However percent normal sperm were weakly associated with RFI in a negative manner. To examine phenotypic relationships between heifer postweaning RFI, and performance, efficiency, HR, and DMD of mid-gestation cows, RFI was measured in growing Bonsmara heifers (N=175). Forty-eight heifers with divergent RFI were retained for breeding. Subsequently, intake, performance and feeding behavior was measured on mid-gestation females. Pregnant females classified as having low postweaning RFI continued to consume 22% less feed, spent 25% less time eating, and had 7% lower HR while maintaining similar BW, ADG and body composition compared to high RFI females. A moderate association between RFI in growing heifers and subsequent efficiency of forage utilization in pregnant cows was found. Growing heifers identified as efficient had greater DMD, however DMD in mature cows was similar between RFI groups. The n-alkane method of predicting intake detected differences in intake between divergent RFI groups in mid-gestation females. Results from this study indicate that inclusion of RFI as a component of a multi-trait selection program will improve feed efficiency of growing animals and mid-gestation females with minimal impacts on growth, body composition, and fertility traits.Item Familiar Food-Induced Feeding Activation in C. Elegans(2011-08-26T17:35:11Z) Song, Bo-mi; Avery, LeonThe growing epidemic of obesity and eating disorders demands the study of regulatory mechanisms of food intake. Studying mutants whose food intake is altered under various conditions has greatly advanced our understanding of the mechanism. However, it is still largely unknown by which mechanisms perception of food activates food intake. The simple anatomy, genetic tractability, and well-characterized and quantifiable feeding behavior and evolutionary conservation of feeding regulators make C. elegans an attractive model system for the study. Food intake in C. elegans requires two muscle motions, pharyngeal pumping and isthmus peristalsis, and the frequencies of the two feeding motions dramatically increase in response to food as in other organisms. I attempted to understand the mechanism underlying food-induced feeding activation by studying the mechanism and the physiological context of action of serotonin, an endogenous activator of pharyngeal pumping. Here I show that like food, serotonin increases overall feeding by activating both feeding motions. Serotonin activates the two feeding motions by activating two distinct neural pathways. A 5-HT7 receptor activated the two motions mainly by acting in the two distinct pharyngeal motor neurons that are essential for food-induced feeding activation. Moreover, the results support that the serotonin receptor activated the two distinct neurons mainly by activating two distinct downstream G protein signaling pathways. Despite the separate regulation, isthmus peristalsis was coupled to the preceding pharyngeal pump. The separate regulation with coupling of the two feeding motions may have evolved to support efficient feeding by allowing control of the ratio of the frequencies of the two muscle motions according to density of food and by preventing futile isthmus peristalsis. Then, which aspect of food triggers the serotonin signal that increases food intake? I found that recognition of familiar food selectively triggers the serotonin signal. Worms selectively consume particular bacteria more actively after experience and the behavioral plasticity requires serotonin signaling. By dissecting the mechanism, I found that recognition of familiar food triggers serotonin release from a pair of chemosensory neurons. The released serotonin acts as an endocrine signal to increase pharyngeal pumping rate by activating the pharyngeal motor neuron that directly triggers pharyngeal pumping. The results suggest that worms form a memory of previously experienced food and that the memory controls food intake. Consistently, the familiar-food induced feeding was strongly dependent on duration of exposure to food to learn but not developmental timing of exposure or nutritional status. Furthermore, worms could remember the previously experienced food at least for several hours. My study provides insight into how feeding organ operates to increase food intake in response to food and how a particular aspect of food controls the process to increase food intake in C. elegans. Studying familiar food-induced feeding activation may help us understand the mechanisms underlying perception of different food and encoding, retention and retrieval of the memory of familiar food.Item Feed Intake and Feeding Behavior Associations with Performance and Feed Efficiency of Feedlot Cattle Fed a Corn-based Diet(2012-02-14) Bailey, JaytonThe objective of the first study was to determine which combination of bimodal (2-population) distribution models best fit non-feeding interval data to distinguish intervals within (1st population) and between (2nd population) meals in beef cattle fed a corn-based diet. Feeding behavior traits were measured in 119 heifers fed a corn-based diet using a GrowSafe system. Bimodal distribution models were fitted to the log10-transformed interval lengths between bunk visit (BV) events for each animal using Gaussian (G); Weibull (W); Log-Normal; Gamma and Gumbel statistical functions. Criterion (AIC) and likelihood probability estimates. Objectives of the second study were to quantify individual meal criterion and examine the associations between feeding behavior traits, performance, and feed efficiency traits in heifers fed a corn-based diet. Results from study one indicate that the G-W bimodal distribution model is a statistically better fitting and likely a more appropriate model to define meal criterion compared to the standard G-G model used in previous literature. Results from the second study suggest that the meal criterion for heifers fed a corn-based diet is 11.48 min when applying the G-W bimodal model to log-transformed interval lengths between BV events. Moderate phenotypic correlations between feed efficiency (residual feed intake- RFI) and several feeding behavior traits were found. Inclusion of these feeding behavior traits to the base model for RFI accounted for an additional 25% of the variation in DMI not explained by ADG or mid-test BW0.75. Significant (P < 0.05) differences in 11 observed feeding behavior traits between RFI classification groups were also found suggesting that differences in feeding behaviors may contribute to the variation in RFI due to differences in energetic costs related to feeding activities.Item Leptin Action on Depamine Neurons: Biochemical and Behavioral Analysis(2009-01-14) Trinko III, Joseph Richard; DiLeone, Ralph J.It has been demonstrated that there are brain regions commonly activated by hedonic foods and drugs of abuse, and therefore, potentially common mechanisms underlying behaviors associated with them. Additionally, the metabolic state of an animal can affect drug seeking behavior. The discovery that leptin receptor (Lepr) is expressed on dopamine neurons in the ventral tegmental area (VTA) provides a link between metabolic state and rewarding behavior. By using a multitude of techniques, the functional roles for Lepr signaling on dopamine neurons have been assessed. By activating Lepr in the VTA via direct infusion of leptin, or conversely reducing Lepr signaling in the VTA with viral-mediated shRNAi, a role for VTA leptin signaling in feeding behavior was demonstrated. Lepr activation in the VTA leads to intracellular signaling pathways similar to that observed in the hypothalamus. These studies also identify differences in signaling between these two brain regions, specifically the phosphorylation of AMP-activated protein kinase (AMPK), which is opposite to what is observed in the hypothalamus. Interestingly, food restriction was found to differentially affect the signaling pathways in the VTA. Preliminary evidence also suggests a role for Lepr in saccharin and cocaine seeking behaviors. Rats with attenuated Lepr signaling in the VTA demonstrate persistent saccharin and cocaine seeking. Conversely, leptin infusions reduced lever pressing during drug withdrawal. These results are indicative of a potential role for leptin in drug and food seeking behavior. In sum, these results suggest a neuronal mechanism by which this key metabolic signal can modify both food and drug intake.