Influences of milk intake and dietary inclusion of a bioactive extract from the olive (Olea europaea) on glucagon-like peptide-2 and its effects on growth and intestinal health of dairy calves

dairy calves;intestinal health;growth;plant bioactive

Morrison, Sarah Yvonne

关键词: dairy calves;    intestinal health;    growth;    plant bioactive;   

Others  :  https://www.ideals.illinois.edu/bitstream/handle/2142/101516/MORRISON-DISSERTATION-2018.pdf?sequence=1&isAllowed=y

美国|英语

来源: The Illinois Digital Environment for Access to Learning and Scholarship

【 摘 要 】

Promotion of intestinal health in preruminant dairy calves is essential for growth and overall health.Yet, a large proportion of dairy calves in the United States is affected by enteric challenges in the preweaning period.Maintenance of intestinal integrity is associated with an intestinal peptide, glucagon-like peptide-2 (GLP-2), which stimulates proliferation, decreases apoptosis, enhances intestinal barrier function, and decreases intestinal inflammation.During diarrheic episodes and at weaning, feed intake is reduced, potentially decreasing gut release of trophic hormones such as GLP-2.Stressors to the small intestine can induce inflammation and increase permeability to pathogens.A dataset was created to quantify the impact of diarrhea on dairy calves in the first 21 d after arrival to the research facility, which was within several days after birth.These data were analyzed to evaluate feed and water intakes, growth, and efficiency in diarrheic calves versus their healthy counterparts in the early preweaning period.Overall, calves that were classified as diarrheic in the first 21 d after arrival had reduced intake of milk replacer and starter dry matter intake, as well as increased consumption of electrolytes to counteract water and electrolytes lost in the feces.Growth and efficiency were also decreased in diarrheic calves compared with healthy calves in the first 21 d after arrival.Additionally, four experiments were conducted to identify methods to stimulate secretion of GLP-2 which, through its associated effects in the small intestine, might maintain intestinal permeability and decrease intestinal inflammation to improve health and growth in young dairy calves.The first experiment sought to characterize the GLP-2 response to four amounts of feed intake and the effect of metabolizable and non-metabolizable glucose supplementation in a 4 × 3 factorial arrangement with 12 treatments.Results indicated that at feed intakes of 75% or greater of control intake (1.75% of BW as DM) GLP-2 secretion was maximized and at intakes <50% GLP-2 secretion became suboptimal.Effect of glucose supplement type on GLP-2 secretion was limited.The second experiment evaluated effects of increasing doses (0, 30, or 60 mg/kg of BW per day) of an Olea europaea extract (OBE) on GLP-2 secretion, intestinal permeability, and diarrhea incidence in pre-weaning dairy calves.The ability to enhance endogenous GLP-2 secretion via the feeding of plant-derived GLP-2 agonists is an attractive and yet unexplored approach for promoting intestinal adaptation and function in newborn calves.If this prediction was met, then the incidence of intestinal disorders and associated preweaning growth limitation should be reduced.Secretion of GLP-2 tended to increase for OBE treatments, and was significantly greater for the higher inclusion rate than for the non-supplemented control.Intestinal permeability in the small intestine was not affected by treatment but there was a significant time effect, with increases in permeability during wk 2, and then permeability decreased with age.Enteric challenges in this experiment were high and the control calves were less likely to have diarrhea than those supplemented with OBE.A third experiment sought to identify the optimal dose of OBE with treatments of 60, 90, 120, or 180 mg/kg of BW per day supplementation.The maximal response of GLP-1 (co-secreted with GLP-2) secretion to each dose was determined in a 5 × 5 Latin square design with 5 calves.A dose of 60 mg/kg of BW per day stimulated the greatest increase in GLP-1 secretion relative to the baseline secretion.A fourth experiment evaluated the effect of OBE (0 and 60 mg/kg of BW per day) on intake, growth, intestinal permeability, intestinal inflammation, and health.Feeding OBE tended to increase prefeeding levels of GLP-1 however, this did not elicit improvements in permeability, intake, or growth in calves that were relatively healthy in the preweaning period.Furthermore, there were no differences in intake, growth, or efficiency during the weaning and immediate postweaning period.Through analysis of mRNA for inflammatory markers isolated from feces, there was some indication that calves supplemented with OBE had a less pronounced inflammatory status relative to control calves.Together, data from these experiments indicate that secretion of gut trophic hormones such as GLP-2 is influenced by feed intake and a bioactive extract targeted at improving intestinal barrier function and health.