Browsing by Subject "amino acid"

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    Forage quality and blood metabolites of horses grazing alfalfa, cool-season perennial grass, and teff
    (2018-07) DeBoer, Michelle
    The impact of forage species on blood metabolites concentrations of grazing horses (Equus caballus L.) is unknown. However, these differences can be crucial as plasma amino acid (AA) concentrations as well as the glucose and insulin response of grazing horses can be indicators of nutritional status or metabolic health. As a result, the objectives of these studies were to determine the impact of different forage species on plasma AA concentrations, protein synthesis, as well as the glucose and insulin response across seasons. Research was conducted in May (spring), July (summer), September (fall), and late October (late-fall) in St. Paul, MN in 2016. However, the data collected was divided into three different studies (1) July samples taken during the first 4 hours were used to evaluate the forage and plasma AA concentrations (2) samples collected in July and September were included in the glucose and insulin response analysis of the regular grazing season and (3) May and October samples were used to analyze the glucose and insulin response during the extended grazing season. Forage treatments included alfalfa (Medicago sativa L.), a mixed perennial cool-season grass (CSG) and teff (Eragrostis tef [Zucc.] Trotter), however, not all forage species were grazed every season. Alfalfa and CSG were grazed in May while CSG and teff were grazed during the October, with all three species grazed in July and September. During these times, forages were grazed by six horses (24 ± 2 yr) randomly assigned to a forage in either a Latin-square or cross-over design. Jugular catheters were inserted 1 h prior to the start of grazing and horses had access to pasture starting at 08:00 h for either 4 or 8 h depending on the season. Jugular venous blood samples were collected from each horse prior to being turned out (0 h) and then at 2 hour intervals following turnout. Plasma and serum samples were collected and analyzed for AA, glucose, and insulin. Corresponding forage samples were taken by hand harvest. Equine muscle satellite cell cultures were treated with sera from grazing horses to assess de novo protein synthesis. Seasons were analyzed separately and data were analyzed using the MIXED procedure in SAS with P ≤ 0.05. When evaluating forage, AA were generally lowest in teff and highest in CSG (P ≤ 0.05). Significant differences in threonine concentration in the plasma were observed; there was no effect on de novo protein synthesis of cultured equine myotubes treated with plasma obtained from the grazing horses (P ≥ 0.20). As a result, although there were significant differences in forage AA content only plasma threonine concentration was different at 4 h with no effect on protein synthesis of cultured equine satellite cells. When evaluating the glucose and insulin response during the regular grazing season, teff generally had lower (P ≤ 0.05) equine digestible energy (DE), crude protein (CP) and nonstructural carbohydrates (NSC) compared to the other forages. Differences in peak insulin were observed between horses grazing CSG and teff during the fall grazing (P ≤ 0.05). Additionally, when evaluating the extended grazing season, teff had lower NSC than CSG in the late-fall (P ≤ 0.05) with subsequently lower average glucose, average insulin, and peak insulin in horses grazing teff compared to CSG (P ≤ 0.05).These results suggest grazing teff could lower the glucose and insulin response of some horses, specifically in the fall and late-fall, and may provide an alternative forage for horses with metabolic concerns,
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    Interrelationships between Soybean Seed Quality Characteristics
    (2016-10) Pfarr, Matthew
    The quality of a protein for animal growth is partially determined by the relative abundance of essential amino acids. Those essential amino acids supplied in the lowest quantity relative to the animal’s requirement limit growth. Examination of soybean protein across genetic sources and environments has indicated that the abundance of potentially limiting amino acids within soybean protein may be influenced by the seed protein concentration. Our objective was to evaluate the effects of seed protein concentration on relative amino acid abundance under controlled environments in order to better understand the biological basis of this apparent relationship. This was accomplished through the use of source-sink treatments that altered seed protein concentration within environments. Increasing the source-to-sink ratio through partial pod removal and open environment treatments significantly increased seed protein; however, the resulting protein was disproportionately enriched in the amino acids glutamic acid and arginine at the expense of the limiting amino acids lysine, cysteine, methionine, threonine, and tryptophan. Defoliation treatments gave the opposite response to pod removal, resulting in a more favorable amino acid balance but with a lower seed protein concentration. Alternatively, the shade treatment increased protein concentration, but the relative concentration of the limiting amino acids was not reduced. This indicates that limiting amino acid abundance is not solely dependent on seed protein percentage and that limiting amino acids may be supplied by the vegetative tissue under C-limited conditions. The ultimate goal of soybean seed improvement is to increase yield while also increasing or maintaining seed protein concentration and the balance of the limiting amino acids. Meeting two of these goals was achieved through the current source-sink treatments as the open environment treatment increased seed yield and protein concentration while shade increased protein concentration and maintained limiting amino acid balance. Meeting all three goals concurrently for soybean improvement was not achieved in the current experiment and may be difficult.