摘要 : Various fat sources are used to increase energy density of diets for lactating dairy cows. Greater energy density should result in increased production responses if DMI is not decreased. Dry fat products are generally believed to ... 展开 Various fat sources are used to increase energy density of diets for lactating dairy cows. Greater energy density should result in increased production responses if DMI is not decreased. Dry fat products are generally believed to be rumen inert and have beneficial physical properties particularly for on-farm use. Partially hydrogenated tallow (PHT) is limited primarily by its greater melting point, which reduces its digestibility and subsequent energy value to the dairy cow. Free fatty acids (FFA) and Ca salts of fatty acids (CaSFA) now have a considerable body of literature for comparison of effects when fed to lactating dairy cows. Direct comparison studies reviewed, which included these two dry fat sources, found primary differences because of increased DMI and palatability when diets contained FFA. Increased DMI and palatability have positive effects on energy balance, milk production, BW change, and reproductive performance with similar digestibility. Mode of action for reduced DMI when using CaSFA appears to be primarily due to negative effects of gastro-intestinal motility, rumen function, and palatability. Reduced DMI impacts the amount and duration of negative energy balance in early lactation, subsequent milk production and reproduction, and economic value. This review found that CaSFA, compared with FFA, reduced DMI, milk protein percentage, and milk production with more variability, but there was a tendency for reduced milk fat percentage and increased BW loss. 收起