COMPARISON OF MILK AND BLOOD-LIPIDS IN JERSEY AND HOLSTEIN COWS FED TOTAL MIXED RATIONS WITH OR WITHOUT WHOLE COTTONSEED

Lipids in milk and blood were examined in Holstein and Jersey cows (8 lactating and 4 dry) fed two TMR containing either 10% whole cottonsee d or a control concentrate mixture of corn, cottonseed hulls, and cott onseed meal in a switchback experiment. Milk from Jersey cows containe d more total lipid than did milk from Holstein cows (4.4 vs. 3.5 g/dl) , had a higher proportion of lipid as triglyceride (97.3% vs. 96.7%), and had a lower proportion of lipid as phospholipid (0.8% vs. 1.0%). M ilk from the group fed cottonseed contained fewer medium-chain fatty a cids (24.4% vs. 29.4%) and more C-18 fatty acids (35.9% vs. 25.8%) tha n did milk from the control group. Total blood lipids were 234 mg/dl f or Holsteins and 168 mg/dl for jerseys. Total blood lipids were higher for dry cows fed cottonseed (100 vs. 72 mg/dl), particularly Jersey c ows. As determined by gravimetric or TLC analysis, milk fat percentage s of cows fed cottonseed were not different from those of cows fed con trol rations. However, as determined by infrared instrumentation, milk fat appeared to be lower (4.3%) for cows fed cottonseed than that (4. 6%) for control cows. Changes in milk fatty acids that were related to diets might explain the difference between infrared and gravimetric d eterminations of milk fat.