The objective was to summarize management practices, identify factors associated with bacterial counts, and describe the variation in total solids concentrations of milk or milk replacer in automated feeders. Six dairy calf operations in Virginia and 4 in Minnesota employing 1 to 2 sophisticated automated calf feeders were visited biweekly for 26 to 28 wk. An initial management survey was conducted for each farm. Observations on facilities, calf weights and heights, blood samples to estimate serum total proteins, treatment records, digital feeding behavior records, and milk or milk replacer (MMR) samples were collected at each visit. Additional milk replacer (MR) samples were collected for 4 wk pre- and post-circuit cleaning. Samples of MMR were plated on Aerobic Plate Count (APC) and Coliform Count (CCP) Petrifilms. Total solids concentration was estimated for MR samples by refractometry. Feeding plans varied widely between farms. Estimates of calf growth were near industry standards, but the proportion of calves receiving treatment was elevated. Least squares mean APC and CCP were 5.26 and 3.01 log10 cfu/ml for Virginia and 3.80 and 0.61 log10 cfu/ml for Minnesota. Circuit cleaning (CC) caused 13 and 16% log reduction in APC and CCP. However, more frequent CC/wk increased bacteria. Mixer/heat exchanger cleanings decreased bacteria during biweekly farm visits. Chlorine bleach reduced bacteria. Use of silicone feeder hoses increased bacteria. A quadratic effect of MMR liters delivered/d was observed; liters delivered > 147 L decreased APC. Automated feeders delivered 12.26% of MR samples > 2% over and 25.71% > 2% under target solids concentration. / Master of Science

Two calf feeding trends are emerging in the dairy industry in the United States. Large herds often find it economical to feed pasteurized waste milk; while smaller herds are embracing technological advancements by utilizing automated calf milk feeders. Housing of calves varies depending on feeding mechanism. Calves fed using autofeeders are grouped together but large herds often find it more labor efficient to house calves individually in elevated wooden crates or polyethylene hutches. Two studies were conducted. The objective of the first field study was to evaluate the influence of diet and housing type on growth and morbidity in 84 Holstein heifer calves in a 2 by 2 factorial experimental design. Calves were housed in either polyethylene hutches or elevated wooden crates with slatted floors. Diets consisted of pasteurized waste milk or the same waste milk supplemented to provide approximately 454 g of milk replacer solids containing 25% protein and 10% fat (LOL Balancer). Calves were randomly placed in 1 of 4 treatment groups 48 h after birth and monitored until weaning (~60 d of age). Body weights and hip heights were measured at time of enrollment and weaning. Milk samples of pasteurized waste milk were obtained five times weekly to measure standard bacteriological plate count, fat, protein and total solids content. All calves were fed 3.3 L of liquid diet via bottle at 0730 and 1530 h. Calves were monitored daily for respiratory and digestive illness and treated according to established protocols. Pasteurized waste milk contained 332,171 ° 733,487 cfu/ mL, 3.51 ° 0.59% fat, 3.13 ° 0.30% protein, and 11.64 ° 1.05% total solids. Housing (P = 0.02) and diet (P = 0.01) affected weight gain, but there was no interaction. Least squares average daily gain for crate and hutches were 0.52 ° 0.024 and 0.59 ° 0.024 kg/d. Least squares average daily gain for waste milk and balancer diets were 0.52 ° 0.024 and 0.60 ° 0.024 kg/d, respectively. Housing or diet did not affect hip height growth/d (0.196 ° 0.007 cm). Health of the calves was not affected by diet or housing. Supplementing waste milk with balancer or housing calves in hutches resulted in higher weight gain. The objective of the second study was to evaluate management, and sanitation and consistency of liquid delivered to calves via automated feeders. Ten herds in Virginia and North Carolina with sophisticated (Förster-Technik, Germany) and basic (Biotic Industries Inc., TN, USA) machines completed a 60-question survey concerning calf and autofeeder management. Duplicate milk replacer samples were obtained to measure sanitation, dry matter, and temperature of milk in the autofeeder at the time of the survey. Six dairies from the original 10 were visited monthly for 3 mo for continued evaluation of sanitation, dry matter, and temperature of milk replacer from the autofeeder. Seven herds utilizing basic machines had a mean SPC of 6,925,000 ° 7,371,000 cfu/ml. The mean dry matter and temperature readings were 12.0 ° 2.1 Brix and 38.8 ° 6.7 °C, respectively. Three dairies that used sophisticated autofeeders had a mean SPC of 1,339,000 ° 2,203,000 cfu/ml. Mean dry matter and temperature readings were 10.37 ° 1.68 Brix and 38.6 ° 6.76°C, respectively. Dairies were also categorized based on management strategies. Producers that purchased autofeeders to manipulate feeding rates, refocus labor to sanitation, and care and well-being of calves, or for technological advancements were successful at rearing calves via autofeeders. Dairy producers who purchased an autofeeder to explore feeding options were not as successful because proper time and management was not dedicated to care of calves or to maintenance of the autofeeder. / Master of Science