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Effect of source of supplemental fat in early lactation on productive performance and milk composition
- Guiling, Ma, Merrill, C., Kung, L., Gressley, T.F., Harrison, J.H., Block, E.
- The Professional animal scientists 2017 v.33 no.6 pp. 680-691
- calcium, dairy cows, dietary fat, dietary supplements, early lactation, fat intake, milk, milk fat, milk fat yield, milk protein yield, oleic acid, palmitic acid, rumen, salts
- The objective of this research was to evaluate the effects of diets supplemented with rumen inert fat sources on early-lactation performance of dairy cows. Two studies were conducted that varied in total dietary fat level (3.4% of DM for study 1 and 5.1% of DM for study 2). Calcium salts of fatty acids (CSFA) rich in oleic acid versus SFA rich in palmitic acid diets were supplemented to provide 0.9% (study 1) and 1.2% (study 2) of total dietary fatty acids (DM basis). Compared with cows fed the CSFA diet in study 1, cows fed the SFA diet had 0.06 kg/d greater protein yield (P = 0.01) and 0.02 unit greater protein efficiency (P = 0.01) expressed as milk CP/CP intake. In study 2, cows fed the CSFA diet had 0.2 kg/d greater fat yield (P = 0.04), 0.1 unit greater fat efficiency (P = 0.02) expressed as milk fat/fat intake, 3.6 kg/d greater 3.5% FCM (P = 0.04), and 3.3 kg/d greater energy-corrected milk yield (P < 0.05). In conclusion, when cows started at 45 DIM and with a diet fat level of 5.1% (DM), the CSFA diet rich in oleic acid improved milk fat yield, milk fat efficiency, 3.5% FCM, and energy-corrected milk (P < 0.05). However, when cows started at greater than 70 DIM and with a diet fat level of 3.4% (DM), the SFA diet rich in palmitic acid improved lactation performance by improving milk protein yield and protein efficiency (P < 0.05). This study suggests that dietary fatty acids are potentially absorbed and partitioned differently depending on the level of dietary fat and DIM.