tailieunhanh - Báo cáo khoa học: "Diet-induced bacterial immunogens in the gastrointestinal tract of dairy cows: Impacts on immunity and metabolism"

Tuyển tập các báo cáo nghiên cứu về bệnh học thý y được đăng trên tạp chí Acta Veterinaria Scandinavica cung cấp cho các bạn kiến thức về bệnh thú yđề tài: Diet-induced bacterial immunogens in the gastrointestinal tract of dairy cows: Impacts on immunity and metabolism. | Dong et al. Acta Veterinaria Scandinavica 2011 53 48 http content 53 1 48 AVS ACTAVETERINARIA tTnTXZ 0 SCANDINAVICA REVIEW Open Access Diet-induced bacterial immunogens in the gastrointestinal tract of dairy cows Impacts on immunity and metabolism Guozhong Dong 1 Shimin Liu2 Yongxia Wu1 Chunlong Lei1 Jun Zhou1 and Sen Zhang1 Abstract Dairy cows are often fed high grain diets to meet the energy demand for high milk production or simply due to a lack of forages at times. As a result ruminal acidosis especially subacute ruminal acidosis SARA occurs frequently in practical dairy production. When SARA occurs bacterial endotoxin or lipopolysaccharide LPS is released in the rumen and the large intestine in a large amount. Many other bacterial immunogens may also be released in the digestive tract following feeding dairy cows diets containing high proportions of grain. LPS can be translocated into the bloodstream across the epithelium of the digestive tract especially the lower tract due to possible alterations of permeability and injuries of the epithelial tissue. As a result the concentration of blood LPS increases. Immune responses are subsequently caused by circulating LPS and the systemic effects include increases in concentrations of neutrophils and the acute phase proteins such as serum amyloid-A SAA haptoglobin Hp LPS binding protein LBP and C-reactive protein CRP in blood. Entry of LPS into blood can also result in metabolic alterations. Blood glucose and nonesterified fatty acid concentrations are enhanced accompanying an increase of blood LPS after increasing the amount of grain in the diet which adversely affects feed intake of dairy cows. As the proportions of grain in the diet increase patterns of plasma p-hydoxybutyric acid cholesterol and minerals Ca Fe and Zn are also perturbed. The bacterial immunogens can also lead to reduced supply of nutrients for synthesis of milk components and depressed functions of the epithelial cells in the .