The effect of nutrition on performance and immune response of dairy animals.

摘要

The majority of dairy cows in the United States are located in areas with selenium (Se) deficient soils. If animals are marginally deficient in Se and/or vitamin E, the responsiveness of their immune system is impaired.;The aim of the first trial was to evaluate the effect of source of selenium (organic vs. inorganic Se) on growth, performance, and immune response of dairy calves and to evaluate the interaction of source of Se and vitamin E dosage (250 IU vs. 1000 IU) on growth, performance, and immune response of dairy calves. The working hypothesis is that high levels of vitamin E (4 times above NRC recommended levels) and organic Se will improve animal performance and immune response. Treatments were incorporated into milk replacers and starter feeds and fed for 85 days. Cellular immune responses were evaluated by Phytohaemagglutinin (PHA) stimulated lymphocyte proliferation and phagocytosis assays. Humoral response was evaluated by measuring antibody titers to bovine herpesvirus type-1(BHV-1) and ovalbumin vaccinations.;There were several significant differences observed with the use of high level of vitamin E and the organic Se. The high level of vitamin E (1000 IU) improved DMI by 11.4%, and ADG by 21% compared with the low level of vitamin E. The interaction of the high level of vitamin E and organic Se (Sel/1000) improved the calves' performance (approximately 4% improvement in BW, 43.5% improvement in ADG) compared with low vitamin E level and inorganic Se (Sod/250). There was a tendency for calves on Sel/1000 diet to have fewer sick days than calves on the Sod/250.;The proliferative response of lymphocytes to PHA stimulation was greatest in females across all treatments. Females on the organic Se had higher proliferative response (1.4 fold) compared with males on the organic and inorganic Se (p0.03). Males on the inorganic Se had higher (1.1 fold) phagocytosis percent compared with females and males on the organic Se and females on the inorganic Se (p0.03). We concluded that 1000 IU/d of vitamin E and organic selenium improved animal performance. Organic selenium improved animal immune response and the interaction between organic Se and vitamin E dosage needs more investigation.;The aim of the second trial was to evaluate the effect of different corn by-products (corn oil, corn germ, distiller grains, and control diet) on immune response in dairy cattle. The working hypothesis is that increased availability of PUFA in corn by-products will decrease neutrophil phagocytosis, oxidative burst, and lymphocyte proliferation. Sixteen multiparous cows (12 Holstein and 4 Brown Swiss, 132 +/- 36 days in milk) were used in a replicated 4 x 4 Latin square design with a 4-week periods. The dietary treatments were: (1) Control diet with corn (CON). (2) Diet containing corn germ (CG). (3) Diet containing dried distiller grains (DDG). (4) Diet containing corn oil (CO). Although neutrophils phagocytosis percent and oxidative burst were not affected by the different fat sources, the lymphocyte proliferative response to PHA was affected. The cows on the CON diet had higher (1.3 fold) proliferative response compared with cows on DDG diet.;The aim of the third trial was to evaluate the effect of different levels of DDGS on the degree of lymphocyte proliferation, the amount of TNF-alpha, and IL-4 present in bovine blood. The working hypothesis was that animals fed high levels of PUFA will produce lower mounts of TNF-alpha, higher amounts of IL-4 and show decrease in lymphocyte proliferation. Twenty-four lactating Holstein cows (12 primiparous and 12 multiparous) were used in randomized complete block design (RCBD) including 4 dietary treatments. The dietary treatments were: (1) 0% DDGS. (2) 7% DDGS. (3) 14% DDGS. (4) 21% DDGS. TNF-alpha concentration was influenced by treatment. Cows on the 14% DDGS had highest TNF-alpha concentration compared with cows on the other 3 experimental diets. Although, IL-4 was significantly influenced by treatments, overall there were no significant differences among treatments and the control. Lymphocyte proliferation responses to PHA or Con A were not influenced by treatments. We concluded that high levels of linoleic acid maybe immunosuppressive (second trial), while moderate levels are not (third trial). The differences between second and third trials maybe due to differences in experimental conditions and overall content of polyunsaturated fat in diet.