Influence of Triglycerides and Free Fatty Acids in Milk Replacers on Calf Performance, Blood Plasma, and Adipose Lipids

In a 4-wk study of 48 3-day-old calves we compared effects of feeding various fats or their free fatty acids in skim milk-powder based milk replacer, on calf performance, feed utilization, and blood plasma and adipose lipids.When fat was fed, calf performance and feed utilization were equivalent for tallow and coconut oil diets but markedly poorer for corn oil.Complete replacement (tallow) or one-half replacement (coconut and corn oils) of the fats with their free fatty acids reduced calf gains and feed efficiency.Tallow free fatty acids gave lower digestibilities of palmitic and stearic acid and reduced calcium absorption.Free fatty acids from both coconut and corn oils reduced diet palatability and intake; those from tallow and coconut oil markedly interfered (in vitro) with rennet clotting of milk replacers.The main lipid classes in blood plasma for all treatments were cholesteryl esters and phosphatidylcholine.High concentrations (56 to 87%) of linoleic acid occurred in cholesteryl esters for all diets despite low concentrations of linoleic acid in the tallow and coconut oil diets.animal-vegetable blends, soapstocks, or other by-products of the edible oil-refining industry.However, these products contain variable amounts of highly unsaturated vegetable oils, peroxidative rancidity products, and free fatty acids (FFA), and there is relatively little information on the effect of these factors on calf performance and diet utilization.Data in (14) suggest that the young calf can tolerate relatively high concentrations of fat peroxides in milk replacer without any deleterious effects on weight gains and feed efficiency.There are reports, however, that feeding highly unsaturated vegetable oils can result in calf scours and poor feed utilization (1, 9, 10).Information is particularly scarce on utilization of FFA by the preruminant calf.Studies with chicks (21) and young pigs (23) demonstrated that fatty acid absorption was better when triglyceride was fed, rather than FFA.The effect appeared to be due to reduced absorption of palmitic and stearic acids in the unesterified form, relative to the 2-monoglycerides formed during triglyceride digestion.We compared effects of feeding equivalent amounts of esterified or unesterified fatty acids in milk replacer on calf performance, feed utilization, and blood plasma and adipose lipids.The esterified fatty acids were provided either by tallow, corn, or coconut oils and the unesterified fatty acids obtained by hydrolysis of the fat and oils.Tallow and corn oil both were composed mostly of long-chain fatty acids (> 14 carbon atoms), tallow highly saturated, and a high proportion of the fatty acids in corn oil unsaturated.Coconut oil provided high intake of medium-chain length fatty acids (8 to 12 carbon atoms).