Recipient Organization
UTAH STATE UNIVERSITY
(N/A)
LOGAN,UT 84322
Performing Department
Animal Dairy & Veterinary Sciences
Non Technical Summary
Objective 1: Addition of fats into dairy cattle diets is a common practice in feeding programs in US. Fat increases energetic efficiency by increasing total energy intake. A factor that has been limiting the utilization of large amounts of fat in dairy cows diet is the negative effect on dietary fiber digestibility. However, recent evidence has indicated that the fatty acid profile of fat supplements has a positive influence on fiber digestibility. We will use an in vitro system to evaluate the modulatory effect of fatty acids on cellulolytic bacteria and consequently fiber digestibility. Increasing fiber digestibility in dairy cows in an important way to improve energy efficiency and feed utilization, while it can minimize the nutrient excretion and environmental impact of the dairy industry.Objective 2: Pre-weaned dairy calves have high susceptibility to bacterial and viral enteric infections because of their immature immune system, which compromises the intestinal barrier function. Accumulating evidence from laboratory animal models indicate that omega-3 fatty acids have a modulatory effect on intestinal epithelial cells as well as in the immune system. Thus, we will be testing if omega-3 fatty acid improves intestinal health in calves during the weaning phase. If our hypothesis is correct, this results will be helpful to formulate milk replacer that supports gut health and consequently enhance animal health and performance.
Animal Health Component
60%
Research Effort Categories
Basic
40%
Applied
60%
Developmental
(N/A)
Goals / Objectives
Our long-term goal is to develop effective strategies for feeding dairy cows and calves to increase animal performance and health, thus promoting efficiency, and farm profitability. This project has two objectives: 1) Determine the effects of palmitic, oleic and stearic acids on ruminal bacterial community composition, bacteria fatty acid composition, and fiber digestibility; and 2) Determine the effects of omega-3 fatty acids on growth, intestinal permeability and plasma biomarkers of inflammation in pre-weaning dairy calves.
Project Methods
One experiment per objective will be performed.In the first experiment, an in vitro system will be used to evaluate the effect of palmitic, stearic and oleic acids on ruminal fermentation. Diets will be randomly assigned to eight 700 mL continuous culture fermenters. Treatments will be arranged in a replicated 4 × 4 Latin square design with four 11-days experimental periods, consisting of 7 days for diet adaptation and 4 days of sample collections. Diet will contain 55% orchardgrass hay and 45% concentrate (dry matter basis). Treatments will be: 1) control diet with no purified fatty acids (Ether extract: ~3.0%); 2) control diet plus 1.5% of palmitic acid; 3) control diet plus 1.5% of stearic acid; and 4) control diet plus 1.5% stearic acid. Feed samples will be collected on days 8, 9, 10, and 11 composed by period and used for chemical analyses (protein, ether extract, and NDF). On days 8, 9, 10, and 11 effluent will be mixed and divided into five subsamples. The first subsample (~400 mL) will be used to analyze dry matter, ash, N, and NDF. A second subsample (50 mL) will be acidified with 3 mL of 6 N HCl and used for NH3-N analysis. A third effluent subsample (50 mL) will be used to determine 15N concentration (an indirect marker of microbial growth). A fourth effluent subsample will be used to determine bacteria fatty acid composition. A fifth effluent subsample (500 mL) will be used for DNA sequencing. Data will be analyzed using the MIXED procedure of SAS.In the second experiment, thirty dairy calves will be used to evaluate the effect of omega-3 fatty acids on intestinal permeability and health. Animals will be housed in individual outdoor hutches bedded with straw and will receive 3.8 L of colostrum from the dam and a control milk replacer for the first two feedings. Calves will be weighted (initial body weight), blocked by date of birth, body weight and parity of the dam, and assigned randomly to treatments in a complete block design. The treatments will be a) 20% animal fat and b) 18% animal fat + 2% flax oil. The milk replacer (26% crude protein) will be prepared commercially and the flax oil will be added before each feeding using an emulsifier added at 3% of the oil. The amount of milk replacer supplied will be 10% of the calf body weight and adjustments will be made weekly. The milk replacers will be diluted at 150 g/L total volume with warm water and fed twice daily (0700 and 1800 h) in equal meals. Calves will be weaned at 42 days of age and in the day after five calves per treatment, randomly selected, will be euthanized and small intestine samples collected. Growth performance including body weight and hip width will be measured when the animals are 4, 14, 28, and 42 days old. Blood samples will be collected at 14, 35, and 42 days of age and analyzed for glucose, insulin, and biomarkers of inflammation (albumin, ceruloplasmin, and haptoglobin). Intestinal permeability of calves will be measured by administering via milk replacer 21 g of lactulose and 4.2 g of D-mannitol on day 14, 35, and 42. Fecal grab samples will be collected two times a day (0700 and 1800 h) on day 12 to 14, 32 to 35, and 44 to 46 and used for apparent nutrient digestibility analysis. All data will be analyzed as a block design using the MIXED procedure of SAS. The statistical model will include the fixed effect of treatment, time and their interaction, and the random effect of block.