Document Type

Thesis - University Access Only

Award Date

2007

Degree Name

Doctor of Philosophy (PhD)

Department / School

Veterinary and Biomedical Sciences

Abstract

It has long been accepted that immunity depends on nutrition. Our knowledge of the effects of nutrition on the immune function now extends beyond clinical nutrient deficiency. In many areas of the world, trace mineral and vitamin deficiencies limit the livestock production through dysfunction in animal metabolism. Oxidative stress may be the link that explains the interactions between animals stress, nutritional deficiencies and decreased disease resistance often observed in the field. The most important biological antioxidants are vitamins A, C, E and selenium (Se), a key component of glutathione peroxidase. Vitamin E is stored in the body of cattle for shorter periods of time and requires dietary supplementation. 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. Twenty four 1-d old Holstein calves were divided into four treatment groups (three males and three females in each group) and supplemented with:l. 0.3 ppm Sel-plex (organic Se) and 1000 IU of vitamin E/calf/day (Sel/1000). 2. 0.3 ppm Sodium selenite and 1000 IU of vitamin E/calf/day (Sod/1000). 3. 0.3 ppm Sel-Plex and 250 IU of vitamin E/calf/day (Sel/250), and 4. 0.3 ppm Sodium Selenite and 250 IU of vitamin E/calf/day (Sod/250). Treatments were incorporated into milk replacers and starter feeds and fed for 85 days. Animal performance parameters and health parameters were measured. 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 (p<0.03). 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 (p<0.03). Calves on the Sel/250 diet had higher BHV-1 (1.42 fold) serum neutralizing antibody titers compared with calves on the Sod/250 diet 6 weeks after booster immunization (p<0.04). Calves on the Sel/250 diet had higher (1.1 fold) antibody titers specific to ovalbumin compared with calves on the Sel/1000 and Sod/250 diets (p<0.04). 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 essential poly unsaturated fatty acids (PUFA), linoleic acid (C18:2) belongs to the omega-6 family, while linolenic acid (Cl 8:3) belongs to the omega-3 family. Linoleic acid is found in most oils (e.g., com, safflower, and sunflower), margarines, and animal fats, whereas a-linolenic acid is found in flaxseed, soybean, and canola oils. Long-chain n-3 PUF A, eicosapentaenoic acid (BP A), and docosahexaenoic acid (DHA) can be synthesized from a- linolenic acid in humans but can be obtained preformed from marine fish oils. These lipids are important in brain development, cardiovascular disease, and cancer, and there is now convincing evidence that dietary n-3 PUFA, particularly EPA and DHA, have a major impact on the function of many components of the immune system. The increased acceptance of ethanol as additive to petroleum fuels has resulted in a significant increase in the volume of distiller's by-product ingredients available to the feed manufacture including corn's distiller's dried grains (DOG) and com distiller's dried grains with solubles (DOGS). These by-products of ethanol production are rich in n-6 PUF A and may hold some value in manipulating the immune system of dairy cattle. The aim of the second trial was to evaluate the effect of different com by-products (com oil, com germ, distiller grains, and control diet) on immune response in dairy cattle. The working hypothesis is that increased availability of PUF A in com 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 com (CON).2. Diet containing com germ (CG). 3. Diet containing dried distiller grains (DOG). 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 DOG diet. The aim of the third trial was to evaluate the effect of different levels of DDGS on the degree o flymphocyte proliferation, the amount of TNF-a, and IL-4 present in bovine blood. The working hypothesis was that animals fed high levels of PUF A will produce lower mounts of TNF-a, higher amounts ofIL-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% DOGS. 2. 7% DDGS. 3. 14% DOGS. 4. 21 % DOGS. TNF-a concentration was influenced by treatment. Cows on the 14% DOGS had highest TNF-a 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.

Library of Congress Subject Headings

Dairy cattle -- Nutrition

Calves -- Nutrition

Immune response

Format

application/pdf

Number of Pages

281

Publisher

South Dakota State University

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