Effect of Pregnancy, Milk Yield, and Somatic Cell Count on Bovine Milk Fat Hydrolysis
K.C. Bachman, M.J. Hayen, D. Morse, C.J. Wilcox
Journal of Dairy Science
Abstract
During 12 mo, 1818 milk samples were collected from Holsteins and Jerseys (n = 261) to evaluate effects of advancing lactation and pregnancy on milk fat hydrolysis. Aliquots, cooled immediately and stored 48 h at 4 degrees C, were analyzed for free fatty acid content. Holsteins had higher acid degree values than Jerseys (.90 vs. .62). No difference in values was detected between alternate a.m. (.74) and p.m. (.76) sampling times. Repeatability of acid degree values from lactation to lactation was low (.22). Days in milk, days pregnant, and milk yield had curvilinear effects on acid degree values, whereas SCC effects were linear. Estimated acid degree value at 335 d in milk (average dry-off) was lowered from .80 to .63 when adjusted for days pregnant and to .48 when adjusted also for milk yield. These responses agree with the increased acid degree values associated with two late lactation events: increasing day pregnant and decreasing milk yield. Estrogen secreted by the developing fetal-placental unit could mediate changes in milk composition that promote milk fat hydrolysis.
Extracted Claims
5 claims extracted from this paper into the knowledge graph
Holsteins have higher acid degree values
“Holsteins had higher acid degree values than Jerseys (.90 vs. .62)”
Days in milk, days pregnant, and milk yield have curvilinear effects on acid degree values
“Days in milk, days pregnant, and milk yield had curvilinear effects on acid degree values, whereas SCC effects were linear”
Estrogen could mediate changes in milk composition
“Estrogen secreted by the developing fetal-placental unit could mediate changes in milk composition that promote milk fat hydrolysis”