Online

Scuderi, Richard Anthony

Animal Sciences

2018

MS

A second experiment evaluated the inclusion of alternative forage crops (AFC) as a means to alter the bovine milk proteome. In this experiment, both the skimmed milk and milk fat globule membrane (MFGM) protein fractions were included in analysis. Milk samples were collected from 16 lactating Jersey cattle included in a 21-d grazing experiment, where cows were offered one of two diets. The control group (CON, n=8) grazed a grass-legume pasture mixture containing orchardgrass (Dactylis glomerata), timothy (Phleum pratense), Kentucky bluegrass (Poa pratensis), and white clover (Trifolium repens). The treatment group (AFC, n=8) grazed a similar base pasture that was strip-tilled with oat (Avena sativa), buckwheat (Fagopyrum esculentum), and chickling vetch (Lathyrus sativus) so that the AFC species comprised 10% of the AFC group⁰́₉s pasture DM intake (DMI). Milk samples were collected for HPLC analysis of the high abundance milk proteins, and LC-MS/MS analysis of the low abundance protein enriched skim milk fraction and MFGM-associated protein fraction. Cows that grazed pastures containing AFC had higher αs1-CAS content (P = 0.005), and higher relative-abundances of 7 low-abundance proteins within the skim milk and MFGM fractions (P less than or equal to 0.05). While it is plausible that the inclusion of AFC in pasture increased nutrient availability to the mammary gland, the specific mechanisms that could have caused the shifts observed remain unclear. Further investigation is necessary to fully understand the role of diet and the milk protein profile.