Browsing by Subject "Animal Sciences"
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Item Backgrounding methods for growing beef cattle and strategies for incorporating alternative feedstuffs into diets of finishing beef cattle.(2011-05) Kelzer, Jolene MadonnaVolatile commodity and cattle markets present challenges for profitable beef production. Four experiments were conducted to evaluate backgrounding methods for growing cattle and utilizing alternative feedstuffs in finishing diets to improve feedlot performance and efficiency. Experiment 1 evaluated the effectiveness of grazing stockpiled and swathed annual ryegrass as backgrounding systems on forage quality and beef stocker cattle performance. Results of experiment 1 suggest grazing stockpiled and swathed annual ryegrass may be viable backgrounding systems; however, forage maturity and winter weather conditions may reduce forage quality and accessibility to levels that can limit stocker cattle performance. Experiment 2 evaluated the effects of reproductive status (spayed vs. intact heifers supplemented with melengestrol acetate) and terminal implant strategy (moderate vs. aggressive) on beef feedlot heifer performance during backgrounding and finishing phases and on carcass characteristics. Results of experiment 2 suggest intact heifers supplemented with melengestrol acetate had greater performance during backgrounding; however, use of moderate or aggressive terminal implant strategies may allow similar performance during finishing and comparable carcass characteristics between spayed and intact beef feedlot heifers. Experiment 3 evaluated the effects of partially replacing dry-rolled corn in traditional corn-based finishing diets with either 35% conventional dried distillers grains plus solubles or 35% high protein dried distillers grains on beef steer feedlot performance and carcass characteristics. Results of experiment 3 suggest that although overall feed intake tended to be reduced, high protein dried distillers grains may successfully replace conventional dried distillers grains plus solubles or up to 35% of dry-rolled corn in finishing beef cattle diets. Experiment 4 evaluated effects of supplemental manganese in high-sulfur feedlot diets containing dried distillers grains plus solubles on in vitro and in vivo ruminal fermentation and hydrogen sulfide gas production. In vitro results of experiment 4 suggest that 1,000 ppm manganese in high-sulfur diets appeared to release less total hydrogen sulfide gas than 0 or 500 ppm manganese; whereas in vivo results suggest beef steers consuming 1,000 ppm manganese may have a less acidic ruminal environment prior to feeding to result in a tendency for reduced average ruminal hydrogen sulfide concentration.Item Biological assessment and methods to evaluate lipid peroxidation when feeding thermally-oxidized lipids to young pigs.(2012-07) Liu, PaiMeasurements of peroxidation can provide useful information regarding the degree of lipid peroxidation, but limitations of each test should not be overlooked. One objective of this disseration was to evaluate peroxidation in 4 lipids, each with 3 degrees of peroxidation. Lipid sources were: corn oil (CN), canola oil (CA), poultry fat, and tallow. Peroxidation levels were: original lipids (OL), slow-oxidized lipids (SO), and rapid-oxidized lipids (RO). To produce peroxidized lipids, OL were either heated at 95°C for 72 h to produce SO, or heated at 185°C for 7 h for producing RO. Five indicative measurements [peroxide value (PV), p-anisidine value (AnV), thiobarbituric acid reactive substance concentration (TBARS), hexanal concentration, 4-hydroxy nonenal concentration (HNE), and 2,4-decadienal (DDE)] and 2 predictive tests [active oxygen method stability (AOM) and oxidative stability index (OSI)] were performed to quantify the degree of oxidation of the subsequent 12 lipids of varying degrees of peroxidation. Analysis showed that a high PV accurately indicated the high degree of lipid peroxidation, but a moderate or low PV may be misleading due to the unstable characteristics of hydroperoxides as indicated by the unchanged PV of rapidly oxidized CN and CA compared to their original state (OL). However, additional tests which measure secondary peroxidation products such as AnV, TBARS, hexanal, HNE, and DDE may provide a better indication of lipid peroxidation than PV for lipids subjected to a high degree of peroxidation. Similar to PV analysis, these tests may also not provide irrefutable information regarding the extent of peroxidation due to the volatile characteristics of secondary peroxidation products and the ever changing stage of lipid peroxidation. For the predictive tests, AOM accurately reflected the increased lipid peroxidation caused by SO and RO as indicated by the increased AOM value in CN and CA, but not in poultry fat and tallow, which indicates a potential disadvantage of the AOM test. Oxidative stability index successfully showed the increased lipid peroxidation caused by SO and RO in all lipids, but it too may have disadvantages similar to AnV, TBARS, hexanal, DDE, and HNE because OSI directly depends on quantification of the volatile secondary peroxidation products. To accurately analyze the peroxidation damage in lipids, measurements should be determined at appropriate time intervals by more than one test and include different types of peroxidation products simultaneously. Few studies had evaluated the metabolic effects of consuming oxidized lipids in pigs. Another objective of this disseration is to evaluate the effect of feeding thermally-oxidized vegetable oils and animal fats on growth performance, liver gene expression, and liver and serum fatty acid and cholesterol concentration in young pigs. A total of 102 barrows (6.67 ± 0.03 kg BW) were divided into 3 groups and randomly assigned to dietary treatments in a 4 × 3 factorial arrangement. The main factors were lipid source (n = 4: CN, CA, PF, and TL) and lipid peroxidation level (n =3: OL, SO , or RO). Pigs were provided ad libitum access to diets in group pens for 28 d, followed by controlled feed intake in metabolism crates for 10 d. On d 39, all pigs were euthanized for liver samples to determine liver weight, lipid profile, and gene express patterns. Lipid oxidation analysis indicated that compared to the OL, SO and RO had a markedly increased concentrations of primary and secondary peroxidation products, and the increased lipid peroxidation products in CN and CA were higher than those in PF and TL. After a 28-d ad libitum feeding period, pigs fed RO tended to have reduced ADFI (P = 0.09), and ADG (P < 0.05) compared to pigs fed OL, and pigs fed CA had reduced G:F (P < 0.05) compared to pigs fed all other lipids. Pigs fed RO lipids tended to have increased liver weight (P = 0.09) compared to pigs fed OL. Liver triglyceride concentration (LTG) in pigs fed OL was greater (P < 0.05) than in pigs fed RO, and tended to be greater (P < 0.07) than in pigs fed SO. The reduced LTG were consistent with increased (P < 0.05) mRNA expression of PPARα factor target genes (acyl-CoA oxidase, carnitine palmitoyltransferase-1, and mitochondrial 3-hydroxy-3-methylglutary-CoA synthase) in pigs fed SO and RO lipids compared with pigs fed OL. Pigs fed CN or CA tended to have increased LTG (P = 0.09) compared to pigs fed TL. Liver cholesterol concentration in pigs fed CN was less (P < 0.05) than pigs fed PF, and tended to be less (P = 0.06) than pigs fed TL, whereas pigs fed CA had a reduced (P < 0.05) liver cholesterol compared to pigs fed PF or TL. In conclusion, feeding thermally-oxidized lipids negatively affected growth performance and liver triglyceride concentrations of young pigs. In addition, limit is known about the effect of thermally-oxidized lipid on lipid energy value and nutrient digestibility in young pigs. A total of 108 barrows (6.67 ± 0.03 kg BW) were assigned to 12 dietary treatments in a 4 × 3 factorial design, plus a corn-soybean meal control diet to evaluate the effect of lipid source and peroxidation level on DE, ME, and apparent total tract digestibility (ATTD) of DM, GE, ether extract (EE), nitrogen (N), and carbon (C) in young pigs. The main factors were lipid source (n = 4: CN, CA, PF, and TL) and lipid peroxidation level (n =3: OL, SO , or RO). Pigs were provided ad libitum access to diets for 28-d, followed by an 8-d period of controlled feed intake equivalent to 4% BW daily. Diets were formulated based on the ME content of CA with the standardized ileal digestible Lys, Met, Thr, Trp, total Ca, and available P:ME balanced relative to NRC (1998) recommendations. Lipid peroxidation analysis indicated that compared to the OL, SO and RO had a markedly increased concentrations of primary and secondary peroxidation products, and the increase in these peroxidation products in CN and CA were higher than those in PF and TL. Addition of lipids to diets increased (P < 0.05) ATTD of EE and tended to improve (P = 0.06) ATTD of GE compared to pigs fed the control diet. Feeding CN or CA increased (P < 0.05) ATTD of DM, GE, EE, N, and C compared to feeding TL, while feeding PF improved (P < 0.05) ATTD of GE and EE, and tended to increase (P = 0.06) ATTD of C compared to TL. Pigs fed CN had increased (P = 0.05) percentage N retention than pigs fed TL. No peroxidation level effect or interaction between lipid source and peroxidation level on DE and ME was observed. Lipid source tended (P = 0.08) to affect DE, but not ME values of experimental lipids (P > 0.12). Digestible energy values for CA (8,846, 8,682, and 8,668 kcal/kg) and CN (8,867, 8,648, and 8,725 kcal/kg) were about 450 kcal/kg higher than that of TL (8,316, 8,168, and 8,296 kcal/kg), with PF being intermediate (8,519, 8,274, and 8,511 kcal/kg) for OL, SO, and RO, respectively. In conclusion, lipid source affected ATTD of dietary DM, GE, EE, N, and C, and N retention rate; and tended to influence the DE value of the lipid, but did not significantly affect their ME value. Rapid and slow heating of lipids evaluated in this study increased lipid peroxidation products, but had minor effects on nutrient and energy digestibility as well as DE and ME values of the various lipids. Furthermore, no information has been reported regarding the effect of feeding peroxidized lipids on intestinal health or immune function in pigs. Another objective of this dissertation is to evaluate the effect of feeding thermally-oxidized lipids on metabolic oxidative status, gut barrier function, and immune response of young pigs. A total of 108 barrows (6.67 ± 0.03 kg BW) were assigned to 12 dietary treatments in a 4 × 3 factorial design in addition to a corn-soybean meal control diet. The main factors were lipid source (n = 4: CN, CA, PF, and TL) and lipid peroxidation level (n =3: OL, SO , or RO). Pigs were provided ad libitum access to diets for 28 d, followed by controlled feed intake for 10 d. After a 24-h fast on d 38, serum was collected and analyzed for α-tocopherol (α-T), thiobarbituric acid reactive substances (TBARS), endotoxin, haptoglobin, IgA, and IgG. On the same day following serum collection, lactulose and mannitol were fed and subsequently measured in the urine to evaluate gut permeability. There was a source × peroxidation interaction for serum α-T concentration where pigs fed SO or RO had decreased (P < 0.05) serum α-T concentration compared to pigs fed OL in CA and CN diets, but not in pigs fed PF and TL diets. There was no source × peroxidation interaction for serum TBARS, but among all lipid sources, pigs fed SO or RO lipids had increased (P < 0.05) serum TBARS compared with pigs fed OL. In addition, pigs fed CN or CA had higher (P < 0.05) serum TBARS compared to pigs fed PF or TL diets. There was no lipid source × peroxidation level interaction, nor lipid source or peroxidation level effects observed for serum endotoxin, haptoglobin, IgA, or IgG. Pigs fed lipid supplemented diets tended to have increased serum endotoxin (P = 0.06), IgA (P = 0.10), and IgG (P = 0.09) compared to pigs fed the control diet. There was no lipid source × peroxidation level interaction, nor lipid source or peroxidation level effects noted for urinary TBARS and lactulose to mannitol ratio. Compared to pigs fed the control diet, pigs fed diets containing lipids had a lower a lactulose to mannitol ratio (P < 0.01). In conclusion, feeding weaning pigs diets containing 10% thermally-oxidized lipids for 38 d, especially vegetable oils containing high concentration of polyunsaturated fatty acids, appeared to impair oxidative status, but had little influence on gut barrier function or serum immunity parameters.Item Detection of complex genetic effects in genome-wide association studies.(2010-07) Ma, LiThe large number of single nucleotide polymorphisms (SNPs) available provides a powerful molecular resource for identifying complex genetic interactions associated with complex traits or diseases but also presents unprecedented data analysis challenges. In this work we developed new quantitative genetics methods and parallel computing tools to detect complex interactive SNP effects underlying complex traits or diseases using genome-wide association studies (GWAS). The new quantitative genetics methods allow detection of novel interactions between genes, sex and environment including second order and third order gene-gene, gene-sex, gene-environment interactions, where each gene may have additive, dominance or parent-of-origin effects. The parallel computing tools allow such complex analysis to be conducted in a timely manner for any large scale GWAS and can be scalable to meet growing data analysis challenges in the future. The analytical and computing methods were applied to the analysis of a Holstein cattle GWAS data set and the Framingham Heart Study (FHS) data. Significant epistasis and single-locus effects were detected affecting human cholestoral levels and dairy production, fertility and body traits. The analytical methods and computing tools will significantly facilitate the discovery of complex mechanisms underlying phenotypes using GWAS.Item Development of tools for genome engineering in swine.(2009-09) Carlson, Daniel FredHeightened interest in relevant models for human disease, in the production of transgenic livestock for biomedical applications, and new and pending releases of genome sequences for rat, cow, and pig have increased the need for improved methods for germline transgenesis. Transpositional transgenesis (TnT) offers an efficient and precise mechanism for genome integration of transgene DNA that avoids incorporation of CG-rich vector DNA and multi-copy transgene concatemerization that can lead to suppression of gene expression and transgene instability. We have developed and tested a transposon toolbox (including Sleeping Beauty, Tol2, piggyBac, and Passport) in pig cells. We have also demonstrated the activity of Cre and Flp recombinases in cultured pig cells and have implemented that technology for regulated activation of gene expression in swine. The application of transposon and recombinase technologies significantly enhances both the means and possible complexity of pig genetic modification. The use of enhanced cis and trans components of the Sleeping Beauty (SB) transposon system for animal transgenesis by pronuclear injection (PNI) resulted in tremendous improvement in the creation of transgenic laboratory mice, rats, and pig embryos, increasing both the frequency of transgenic founders, and the number of transgenes per founder, overall elevating the number of potential transgenic lines by 10-20-fold. Genetic modification of pigs by tandem pig transgenesis and cloning also benefits from TnT, resulting in multiple independent insertions per cellular clone which permits the assessment of several alleles upon segregation from a single founder. Finally, towards the development of a porcine model of cystic fibrosis (CF), we’ve created a mouse phenocopy of CF based on RNA interference using the SB transposon system. Building on insights gained in CFTRRNAi mouse, we’ve developed tightly regulated CFTRRNAi alleles in pigs to circumvent the lethal neonatal meconium ileus that confounds the CFTR-knockout model, hopefully simplifying investigation of postnatal CFTR deficiency in a large animal. Given its simplicity, versatility and high efficiency, TnT represents a compelling non-viral approach to modifying the porcine germline.Item The effect of dietary trace minerals during late gestation on health and performance of the dam and progeny.(2011-08) Golombeski, Gregory LeonardThe objective of this study was to investigate the effects of supplemental dietary trace mineral source and zinc concentration during the non-lactating period of approximately 60 d prepartum on: 1) dairy cow performance through 150 days in milk and; 2) composition of colostrum and calf performance. Fifty-two Holstein and cross-bred cows were utilized at the University of Minnesota (U of MN) St. Paul dairy (STP) and 62 Holstein cows at the U of MN Northwest Research and Outreach Center (NWROC, Crookston, MN) dairy. Treatments were: 1) 100% inorganic trace mineral supplementation (CON); 2) organic trace mineral supplemented at the following rate: 40% of supplemented zinc (Zn), 24% of supplemented manganese (Mn), 69% of supplemented copper (Cu) and 100% of supplemented cobalt (Co) supplied by 4-Plex (Zinpro Corp., Eden Prairie, MN; OTM) and 3) OTM with additional Zn from Zn-methionine (OTMZ). Dietary trace mineral supplements were formulated to provide similar amounts of Co, Cu and Mn. Dietary Zn supplemental amounts were similar for CON and OTM (75 mg/d), but approximately two times higher for OTMZ. Heifer calves born from the cows at STP and all calves born at NWROC were evaluated for feed intake and growth performance through 56 d of age. Bull calves born at STP were used in a study to evaluate the affect of additional Zn on intestinal development. Under conditions of the current study, treatment during the dry period did not have an effect on milk yield. Number of pregnant multiparous cows at NWROC fed OTMZ tended (P = 0.09) to be greater at 150 days in milk compared to CON and OTM. There were no effects of treatment on colostrum protein or immunoglobulin concentration at either location. For STP and primiparous cows at NWROC, treatments did not significantly affect the fat content of colostrum. Treatment did affect colostrum fat concentration from multiparous cows at NWROC with cows fed OTMZ having a higher concentration of fat in colostrum than cows fed CON. No effect of treatment was observed on liver TM concentration, hematology profile, and intestinal villus height or crypt depth under the conditions of this study.Item Impact of alfalfa hay neutral detergent fiber concentration and digestibility on Holstein dairy cow performance, diet digestibility and chewing behavior.(2010-01) Raeth-Knight, Mary LouiseOur objectives were to determine the effect of alfalfa hay in vitro neutral detergent fiber digestibility (IVNDFD), compared within relatively low and high neutral detergent fiber (NDF) concentration hay pairs, on Holstein dairy cow performance, apparent digestibility, chewing activity and rumen parameters. Treatments (Lh, Ll, Hh and Hl) included four alfalfa hays selected for low (L) or high (H) NDF concentration and low (l) or high (h) 48-h IVNDFD within NDF concentration pairs. Three studies were conducted. During Study 1 and 2, alfalfa hays were included at 15% of the diet DM. Study 3 was a short-term study (21-d) in which alfalfa hay was fed at 96% of the diet DM. Analysis of alfalfa hay grab samples taken during study 1 confirmed that within the high NDF hays (Hh and Hl) there was no difference in NDF concentration and the Hh hay was 6.8 percentage units higher in IVNDFD compared to Hl. However, within the low NDF hays (Lh and Ll), NDF concentration was 3.8 percentage units higher for the Ll compared to Lh hay and there was no difference in IVNDFD. Therefore, our original study design was not maintained. As a result, we evaluated the impact of alfalfa hay IVNDFD on response variables for the high NDF hay diets and the impact of alfalfa hay NDF concentration on response variables for the low NDF hay diets. When alfalfa hay was fed at 15% of the diet DM, there was no impact of alfalfa hay NDF concentration or IVNDFD on DMI, fat corrected milk (FCM) yield, milk fat, or protein yield among treatments. Within the low NDF hay diets, apparent total tract DM digestibility (DMD) was 6.6 percentage units higher for the Ll compared to the Lh hay diet and there was a trend for higher apparent total tract NDF digestibility (NDFD) for the Ll compared to Lh hay diet. For the high NDF hay diets, a difference in alfalfa hay IVNDFD of 6.8 percentage units did not affect total tract DM or NDF digestibility. Neither alfalfa hay NDF concentration nor IVNDFD affected rumen pH or VFA concentrations. When alfalfa hay was included at 96% of the diet DM, there was no difference in DMI, 3.5% FCM, milk fat or protein yield among treatments. Within the low NDF hay diets, apparent total tract DM and NDF digestibility were 14.7 and 18.4 percentage units higher for the Lh compared to Ll hay diet. In contrast, within the high NDF hay diets, apparent total tract DMD was 11.1 percentage units higher for the Hl compared to Hh hay and there was no difference in apparent total tract NDFD. Our results suggest that small differences in alfalfa hay IVNDFD or NDF concentration, especially when alfalfa hay is fed at a low dietary inclusion level, should not be expected to have a significant impact on dairy cow lactation performance. Given the challenges associated with forage sampling and IVNDFD repeatability, effectively implementing IVNDFD data in diet formulation for dairy cows is difficult.Item Supplementation of progesterone on establishment of pregnancy, resynchronization of estrus, and development of in vitro-produced bovine embryos.(2009-02) Larson, Jamie ElizabethProgesterone is necessary for the maintenance of pregnancy and has been associated with embryonic mortality. Five experiments were conducted to discover the role of progesterone on establishment of pregnancy, resynchronization of estrus, and development of in vitro produced bovine embryos. The objective of experiment 1 was to determine whether an ovulatory estrus could be resynchronized in previously synchronized artificially inseminated (AI) nonpregnant cows without compromising pregnancy from the previous synchronized ovulation or to those inseminated at the resynchronized estrus. Treatments consisted of a vaginal insert containing progesterone administered after a timed AI (TAI) at different timepoints, and for differing durations. It was determined that pregnancy rates to the initial TAI were similar and the resynchronization of estrus was successful in two treatments, however, fertility in those treatments was decreased. In experiment 2, we established the concentrations of progesterone in the lumen of the uterine horn and oviduct to establish a base concentration to be used in further experiments. Using uterine flushes of estrus synchronized heifers and fluid collection of reproductive tracts post-slaughter; we determined that, while concentration of progesterone was highly variable in females, the mean was nearly 1 ng/mL. The objectives of experiments 3 and 4 were to determine the effects of culturing in vitro produced embryos with or without a co-culture of bovine oviductal epithelial cells (BOEC) with or without two concentrations of progesterone on embryo development. We determined that co-culture of bovine embryos with BOEC decreased development and the addition of progesterone decreased development of embryos. The objective of experiment 5 was to determine if the addition of two concentrations of progesterone at two stages of culture impacted embryo development, embryo metabolism and numbers of cells in each embryo. We determined that while some characteristics changed slightly with the addition of progesterone, overall viability was not increased or decreased dramatically. Our conclusion was that although we do not fully understand the role of progesterone on embryonic mortality, we were unable to affect pregnancy rate or embryonic development with the concentrations and timing of progesterone employed in these experiments.