EFFECT OF WHOLE COTTONSEEDS AND CALCIUM SALTS OF LONG-CHAIN FATTY-ACIDS ON PERFORMANCE OF LACTATING DAIRY-COWS

Holstein cows were assigned to diets containing no supplemental fat, s upplemental fat from whole cottonseed, or supplemental fat from whole cottonseed plus Ca salts of fatty acids (Megalac(R)). The TMR containe d 46% forage and 54% concentrate or mixtures of concentrate and whole cottonseed on a DM basis and were fed from wk 3 through 44 of lactatio n. The mean fat content of the three diets was 3.0, 4.7, and 6.4% of D M for control, whole cottonseed, and whole cottonseed plus Ca salts of fatty acids, respectively. Supplemental fat increased NE(L) intake, p ercentage of milk fat, milk fat production, and rate of recovery of BW and body condition. Supplemental fat decreased milk protein productio n in early lactation, but not in late lactation. Addition of supplemen tal fat had no significant effect on ruminal concentration of VFA, NH3 N, or in situ digestibility of fiber. The proportion of unsaturated f atty acids in milk fat was increased with supplemental whole cottonsee d or whole cottonseed plus Ca salts of fatty acids. During the first 3 mo of lactation, the proportion increased of fatty acids C-14 or less , C-16, and C-18:2. Proportion of fatty acids C-16:1 and C-18:1 corres pondingly decreased. The change in composition of milk fatty acids dur ing early lactation is consistent with the use of body fat for milk sy nthesis.