Browsing by Author "Dr. Jack Odle, Committee Chair"

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    Improving Fat Utilization by the Weaned Pig: Effect of Diet Physical Form, Fatty Acid Chain Length, and Emulsification.
    (2008-04-07) Price, Kathryn Leigh; Dr. Jack Odle, Committee Chair; Dr. Eric van Huegten, Committee Member; Dr. Peter Ferket, Committee Member
    Previous research indicates that dietary fat utilization by the newly-weaned pig is low, while fat digestive capabilities prior to weaning are very high. Sow milk contains approximately 40% fat, whereas nursery diets are rarely formulated to contain more than 5%. The aim of this experiment was to determine if emulsification (plus or minus Tween-80), physical form of the diet (liquid vs dry) or fatty acid chain length (medium (MCT) vs long chain triglyceride (LCT)) effect fat utilization by the newly weaned pig. Two replicates were performed in the summer of 2006 at the NCSU Swine Educational Unit. Pigs (N= 96) were weaned at 20 ± 0.30 d of age (6.8 ± 0.04 kg) and fed one of eight dietary treatments for 14 d according to a 2x2x2 factorial design. The MCT fat contained primarily C8 and C10 fatty acids while the LCT fat was supplied by choice white grease. Each fat was spray dried with or without the inclusion of Tween-80 emulsifier (at 2% w⁄w) and comprised 12% of the final diets. Diets were otherwise formulated to exceed NRC nutrient requirements. Liquid diets were reconstituted with water to 13% dry matter and were offered ad libitum via milk-replacer feeders (Kane Manufacturing). Diet physical form greatly accelerated piglet growth (P < 0.05), with liquid-fed pigs (0.49 kg⁄d) out gaining dry-fed pigs (0.340 kg⁄d) by 44%. Triglyceride chain length also impacted growth (P < 0.05), with pigs fed LCT outperforming MCT-fed pigs by 23%. Effects of emulsifier were not detected (P > 0.1) in growth performance. Accelerated growth was accompanied by elevated feed intake which was 17 % greater for liquid-fed than for dry-fed pigs and was 21% greater for pigs fed LCT vs MCT. Accordingly, gain:feed was improved by 29% in liquid-fed pigs (P < 0.05). A comparison of two digestibility markers, C 36 alkane and Co-EDTA, was examined in this trial. The use of Co-EDTA resulted in a statistically (P < 0.05) greater digestibility over the C 36 marker. However, it is unclear as to which marker is the more accurate when trying to determine fat digestibility. C 36 was used to determine all digestibility data and diet physical form had no effect (P > 0.1) on digestibility. The digestibility of the fat was higher (P < 0.05) in the MCT fat over the LCT fat (98.42% vs 93.39%, respectively). Emulsification increased the digestibility of the LCT fats and this effect was more evident in the long chain saturated fatty acids (P < 0.05). Ileal and Jejunal morphology showed increases in the villus height as the pigs aged (P < 0.05). Emulsification of the fat resulted in an increased Ileal villus height (P < 0.05) in all diets except for the liquid MCT fed pigs that were 14days post weaning. Plasma ketone body concentrations were significantly (P < 0.05) greater in the MCT fed pigs and interaction between chain length and diet physical form was observed. Pigs consuming the dry MCT diet had a higher plasma ketone body concentration followed by liquid MCT, liquid MCT, and finally dry LCT fed pigs. Collectively, we infer that feeding liquid diets containing emulsified long chain triglycerides can increase growth performance for the entire weaning period. Additionally, new processing technologies such as spray drying fat may be beneficial to improving piglet performance immediately post weaning.
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    The Piglet As A Model Of Norwalk Gastroenteritis
    (2002-12-02) McPhatter, Lisa Anastasia; Dr. Anthony Blikslager, Committee Member; Dr. Lee-Ann Jaykus, Committee Member; Dr. Jack Odle, Committee Chair
    Norwalk-like viruses (NLV) are the most important cause of acute gastroenteritis in humans. However, little is known about their pathogenesis since no cell culture or animal model is available yet. Therefore, we have investigated if young piglets would be a suitable model to study NLV pathogenesis. Sixteen ∼21-d-old piglets were orally gavaged with 3 doses of the NLV prototype strain (Norwalk virus; strain 8FIIb) previously confirmed to be infective for human volunteers. Stool samples were collected daily to assess viral shedding. Exposure to Norwalk virus had no detectable effect on pig growth. Using RT-PCR, viral NV-RNA was detected in two (high dose) of the twelve pigs gavaged with virus. In a second study, colostrum-deprived newborn piglets were orally gavaged with either the human strain (8FIIb, n=4), swine calicivirus (n=6) or a saline control (n=5). Neither swine calicivirus nor Norwalk virus could be detected by RT-PCR in any stool samples. At day 4 post infection intestinal samples were collected for histological and biochemical evaluation. Differences in diarrhea score and intestinal lactase activity were not detected, but weight gain of pigs infected with the swine calicivirus (158 g/d) was lower (P<0.05) than control pigs (280 g/d). In addition, there was a 49% reduction in ileal villus height in the swine calicivirus group (P<0.05). These results are consistent with swine calicivirus-induced villous atrophy, and attendant reduction in nutrient absorption.
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    Unraveling the Pathway of Lipid Oxidation in the Young Pig: Assessment of Hepatic beta-oxidation and Characterization of Carnitine Palmitoyltransferase I (CPT I)
    (2004-12-10) Lyvers Peffer, Pasha A; Dr. William Miller, Committee Member; Dr. Jack Odle, Committee Chair; Dr, Joan Eisemann, Committee Member; Dr. Robert Harrell, Committee Member
    Hepatic β-oxidation and liver and skeletal muscle carnitine palmitoyltransferase I (CPT I) activity and mRNA expression were evaluated in the pig. In the first study, newborn pigs were allotted to one of four dietary regimens: artificial milk replacer with long chain triglycerides (LCT) as the fat source (Control), the Control diet with 0.5% clofibric acid (CA), the Control diet with medium chain triglycerides replacing LCT as the fat source (MCT), or the Control diet with 40 ppm isoproterenol (ISO). There were no differences between Control and MCT or ISO supplemented groups in total, mitochondrial, or peroxisomal β-oxidation of [1-¹⁴C]-palmitate (1 mM). Total and peroxisomal β-oxidation increased 134 and 186%, respectively, with CA supplementation. Hepatic malonyl-CoA sensitive CPT activity increased (p < 0.05) in pigs receiving CA. Changes in relative expression of hepatic LCPT I and skeletal muscle MCPT I mRNA amounts following clofibrate supplementation were not detected, while a modest effect on acyl-CoA oxidase (ACO) relative mRNA amounts was observed (p=0.08). In the second study, hepatic and skeletal muscle CPT I kinetics in pigs during different stages of development were evaluated. Activity of CPT I increased 109 and 67% between birth and 1 wk of age in liver and skeletal muscle, respectively (p < 0.05). Realtive expression of hepatic CPT I mRNA in the 24 hr old pig was 7% of the amount detected in the newborn (p < 0.001); while hepatic CPT I apparent Km for carnitine decreased 48% from birth to 3 wk of age. The apparent Km for carnitine in skeletal muscle decreased from birth to 1 wk of age, then increased 200% between 1 and 5 wk of age (p< 0.01). Plasma and liver free carnitine concentrations increased 200 and 160%, respectively, during the first day of life (p < 0.05). High relative expression of γ-butyrobetaine hydroxylase (γBBH) in the kidney indicated high capacity for de novo carnitine synthesis by this tissue. Collectively, the findings from this research are important in understanding how the pig, a species with a low capacity for β-oxidation, utilizes fatty acids.