Browsing by Author "James Petitte, Committee Member"

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    Development of Claudin 2 and Claudin 4 in Embryonic and Hatched Chick Intestine
    (2008-12-04) Wingate, Marvin Jason; Betty Black, Committee Chair; James Petitte, Committee Member; Brenda Grubb, Committee Member
    The epithelium of the vertebrate intestine is a dynamic structure, under constant renewal. The intestinal crypts represent a proliferative compartment that is monoclonal and is maintained by multiple stem cells. Epithelial cells migrate up the villus in sheets where they differentiate into enterocytes and goblet cells. A defining characteristic of the epithelial sheets are tight junctions that behave as a primary barrier to the diffusion of solvents through the paracellular pathway in both epithelia and endothelia. This work utilized Western blotting to study the expression of two tight junction proteins, claudin 2 and claudin 4, in duodenal epithelial cells from pre- and posthatched chick intestine during development, as well as along the crypt-villus . Claudin 2 expression was stronger at 20 days of incubation than at 18 days and had the greatest expression in epithelium from 2-day old chicks. Additionally, claudin 2 was found to decrease up the crypt-villus axis in duodenal epithelium from 2-day old chicks. The claudin 2 crypt-villus axis gradient is present by 20 days of embryonic development, at the onset of crypt formation. The localization of claudin 2 in the crypts at 20 days may establish the adult pattern of tight junctions and prepare the intestine for the absorptive functions required soon after hatching. Conversely, claudin 4 was not detected in late embryonic or early posthatch duodenal epithelium. Claudin 4 was expressed in the intestinal epithelium of 3-week old chickens; its expression may be dependent on feeding or other physiological factors. Committee Chair: Betty L. Black Committee Members: Brenda J. Grubb, James N. Petitte
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    Mediating Bone Mineralization Status in Laying Hens by Feeding Increased Calcium during Rearing and the Lay Cycle
    (2009-05-01) Fosnaught, Mary Helen; Donna Carver, Committee Member; Jesse Grimes, Committee Member; James Petitte, Committee Member; Ken Anderson, Committee Chair
    Trends to decrease the age of sexual maturity and point of lay without concurrent increases in dietary Ca may reduce the potential for full skeletal mineralization in pullets. During lay, the hen’s increased genetic capacity to produce more eggs with less feed without respective increases in dietary Ca may further predispose hens to bone weakness leading to welfare and livability issues. Objectives of this research were to evaluate the effect of feeding increased calcium during rearing and the lay cycle as well as strain and density on laying hen performance and bone mineralization status. Pullets were grown to 16 wks in a grow house with 52 pullets/replicate and 28 replicates/treatment (5,824hens total) which were then moved to a lay house from 18-66 wks with either 24 or 36 hens/replicate (at 48 or 64 sq in) so that there was a total of 26 replicates/treatment (5,728 hens total). The 2 x 2 factorial arrangement of treatments during rearing were Leghorns strain: Hy-Line W-36 (H) and Babcock B-300 (B) and Ca:P ratios: elevated (RC+) Ca:P 2.14, 3.14, 4.14 and control (RC) Ca:P 2.14, 2.14, 2.42 ratio of starter (0-6 weeks), grower (6-12 weeks), and developer (12-17 weeks), respectively. In the lay cycle, the 2 x 2 x 2 x 2 factorial consisted of strain, rearing diet, layer dietary regimens: increasing Ca and P (LC+) and constant (LC) and cage densities: low, 64in2/bird (LD) and high, 48in2/bird (HD). All diets were isocaloric and fed ad libitum. Feed consumption (FC) and BW were monitored bi-weekly (by period) beginning at 2 weeks of age during the rearing and every 4 weeks during the layer phase. Mortality and egg production was recorded daily. During rearing, 5 femurs/trt and during laying, 3 femurs/trt were measured for dry fat-extracted bone weight (DFEW), % ash, volume, and bone breaking strength (BBS) from week 6-16 and from weeks 51-61, respectively. From week 0-17, FC was higher (P≤0.01) when feeding RC+ (5.11 kg) than RC (4.81 kg) otherwise there was no effect on Gain (1,017 and 1,029 g, respectively, P=0.53) or FE (0.199 and 0.214, respectively, P=0.08). Strain had no effect on FC, Gain, or FE. Mortality increased (P≤0.03) by period in the B compared to H strain. Layer performance was not affected by feeding the increased calcium during rearing or lay. Strain effected (P≤0.05) feed consumption, feed efficiency, egg production, and mortality. Feeding more Ca during rearing increased DFEW (RC+=0.94 g vs. RC=0.82 g, P=0.04) while strain effected bone volume (H=2.99 and B=2.37 cc, P≤0.01) and femoral BBS (B=8.55 vs. H=7.80 kg, P=0.01) of pullets. Feeding more Ca during lay did not effect bone status, but feeding it during rearing increased BBS (RC+=14.15 vs. RC=12.37 kg, P≤0.01) in older layers. Strain effected (P≤0.001) both BBS (H=14.26 vs. B=12.26 kg) and volume (H=5.90 vs. B=6.27 cc). These findings indicate that feeding increased Ca during rearing and laying impacts bone mineralization and may be a useful strategy to mitigate bone weakness and such related conditions as cage layer osteoporosis.