Six primiparous cannulated cows were assigned to six treatments in a 6 x 6 Latin square design to evaluate the effects of degree of fat saturation and amount and source of effective fiber on site of nutrient digestion and milk production. Cows were fed for ad libitum intake a control diet with no added fat or diets with 5% added fat from saturated tallow, tallow, or animal-vegetable fat; the diets with animal-vegetable fat had 40% forage, 40% forage plus 20% soyhulls, or 60% forage. Ruminal acetate:propionate was higher when soyhulls replaced forage NDF because of the higher digestibility of soyhulls in the rumen and total tract. Ruminal digestion of NDF was decreased as unsaturation of fat increased. True and apparent efficiencies of bacterial protein synthesis were increased as fat unsaturation increased, probably because of reduced recycling of microbial N in the rumen. The digestibility of fatty acids in the small intestine was higher in cows fed no fat than in those fed fat and was reduced as fat unsaturation decreased, primarily because of the saturated tallow. Dry matter intake was decreased 14% by increased fat unsaturation. All fat supplements depressed milk protein percentage. Production of 4% FCM tended to decrease linearly as unsaturation of fat increased. In diets with 5% added fat, a degree of saturation between saturated tallow and tallow (iodine values of 18 and 62) appears to be optimum for fatty acid digestibility and DMI.

Five primiparous Holstein cows were cannulated in the rumen, duodenum, and ileum and were fed diets containing 50% alfalfa silage and 36.6% coarse-, medium-, or fine-ground corn (CGC, MGC, and FGC, respectively, with mean particle sizes of 4.8, 2.6, or 1.2 mm), steam-rolled corn (SRC; density of 0.53 kg/L), or a 50:50 mix of CGC and SRC (SC) to evaluate how corn processing affects site of digestibility of nonstructural carbohydrates (NSC) and neutral detergent fiber (NDF). Decreasing the particle size of corn quadratically affected true ruminal digestibility of NSC (49.8, 46.5, and 87.0%, respectively). Because of compensatory digestion postruminally, a smaller increase (from 91.3 to 98.0%) in total tract digestibility of NSC was noted as particle size decreased. A small but significant linear shift in NDF digestion from the rumen to the large intestine was detected as corn particle size decreased. The addition of SRC to CGC linearly increased true NSC digestibility in the rumen about 20 percentage units but had much smaller effects on total tract digestibility. Despite the large impact of corn processing on NSC digestibility in the rumen, flow of bacterial N to the rumen was not affected by treatment. Reducing the particle size of corn decreased the apparent escape of corn protein, but steam-rolling had no effect. Corn should be finely ground to maximize total tract OM digestibility or steam-processed to densities less than 0.53 kg/L for maximal starch digestibility. However, fine-grinding or steam-processing of corn may have only a modest impact on total tract OM digestibility.

Cattle with a synovial fluid total NCC > 25,000 cells/microL, a PMN cell count > 20,000 cells/microL or more than 80% PMN cells, and TP > 4.5 g/dL should be considered to have infectious arthritis.