Sawall, Zachary2015-08-132015-08-132015-04https://hdl.handle.net/11299/173809University of Minnesota Ph.D. dissertation. April 2015. Major: Animal Sciences. Advisors: Noah Litherland, Brian Crooker. 1 computer file (PDF); xiii, 162 pages.Eighty PVC mini silos were used to evaluate corn silage fermentation characteristics with four homo- or heterofermentative inoculants. Freshly chopped corn silage was untreated Control (CON), or treated with Promote HN-3 (PHN), Promote LC-1000 (PLC), or Vigorsile EBL II (VEBL) before packing. Silos were opened at d 30, 60, 90 and 120 d. Averages over all time points, PLC and VEBL reduced pH compared to CON, and PLC had greatest lactic acid concentration and In vitro starch digestibility compared to CON, PHN, and VEBL. Ninety-six PVC mini silos were used to evaluate corn silage fermentation characteristics with four homo- or heterofermentative inoculants. Freshly chopped corn silage was untreated Control (CON), or treated with Promote AP (AP), Promote EBL (EBL), or Promote BP (BP) before packing. Silos were opened at d 30 and 90. After 90 d ensiled, corn silage with BP had higher pH, lower lactate, higher acetate concentration, and increased aerobic stability compared to CON, AP, and EBL. A 2 × 2 factorial randomized block design was used with 17 cows/treatment or 8 primiparous cows/treatment resulting in four treatments; 1) low starch + carrier (LSC), 2) low starch + Propionibacterium freudenreichii strain P169 (P169) (LSM), 3) high starch + carrier (HSC), 4) high starch + P169 (HSM). Starch amount was 15.5% and 26.7% prepartum and 20.1% and 29.7% postpartum. Multiparous cows fed HSM produced the greatest milk yield. Milk yield was similar for LSM and HSC. Feed efficiency was increased with P169. High starch tended to increase 3.5% fat corrected milk and energy corrected milk yield in primiparous cows. Also, high starch increased postpartum liver total lipid and triacylglycerol content. A retrospective analysis was conducted using 161 multiparous dairy cows to investigate easily measured, low cost variables correlated to subclinical ketosis in fresh cows. In addition, 328 cows from two commercial dairy farms were utilized to develop a ketosis prediction model (Pre-K) using day of calving data: colostrum yield (CY), body condition score, and parity. An increase in CY correlated with an increase in beta-hydroxybutrate concentration on d1 and 7. Pre-K model resulted in a sensitivity of 60% and specificity of 64% for predicting cows at risk for ketosis.enketosisP169silage inoculantsstarchtransition cowThesis or Dissertation