Name: Impacts of feeding lipid supplements high in palmitic acid or stearic acid on performance of lactating dairy cows
Author: M.B. Chamberlain & E.J. DePeters
ABSTRACT: Effects of feeding lipid supplements high in free fatty acids (FAs) of palmitate (C16:0) or stearate (C18:0) plus C18:1 cis 9&10 on milk yield and composition, apparent whole-tract apparent digestibility of FA, and the FA composition of milk lipids were studied. Four lactating Holstein cows with ruminal cannulae were used in a 4 × ۴ Latin square assignment of four dietary treatments. Lipid supplements were enriched in free fatty concentrations of either palmitic acid (P) or stearic acid (S). The total mixed-ration contained 20 g/kg of lipid supplement that consisted of varying proportions of P to S. Treatments were: 100:0 P:S (P), 0:100 P:S (S), and two mixtures including 66:34 P:S (PS) and 34:66 P:S (SP). Milk yield and dry matter intake were not affected by lipid supplement, but the concentration and yield of fat in milk increased with increasing C16:0 in the lipid supplement. Increasing the C16:0 concentration in the lipid supplement increased its concentration in milk lipids while increasing C18:0 in the lipid supplement increased C18:0 concentration in milk fat. Whole-tract apparent digestibility of neutral detergent fiber (NDF) did not differ with lipid supplement, but organic matter digestibility tended to decrease with increasing C18:0 in the lipid supplement. Whole-tract digestibility of total FAs decreased with the increasing proportion of C18:0 to C16:0 in the lipid supplement. Apparent digestibility of C16:0 and C18:0 was not different within dietary treatment. The FA composition of the lipid supplement impacted both whole-tract digestibility of FAs and FA composition of milk lipids.
KEYWORDS: Fatty acids, palmitate, stearate, apparent digestibility, dairy cows