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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 × 4 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. ARTICLE HISTORY

M-series x-ray emission spectra from cerium have been recorded for near-threshold electron excitation.For incident electron energies near the Mv and Miv inner-shell ionization energies, the spectra are dominated by intensity resonances of structures which are part of the continuous spectrum near its high-frequency limit. The intensity and position dependencies of the resonating structures are presented and are interpreted as arising from resonances in the cross sections for scattering electrons into empty 4f levels. No such resonances mere observed for excitation energies near the M,«and M" inner-shell ionization energies.

P-GaP photoelectrodes are of interest as cathodes in photosynthetic photoe]ectrochemical devices. The nature of the surface appears crucial to the efficient utilization of this material. In this study we show how an oxide surface layer is present even in the reductive environment at the surface; that this layer appears to be necessary for efficient interfacial charge transport; and that high solution oxygen concentrations increase the stability of this layer and consequently the electrode. Aging experiments with chemical and surface analyses are included that support these surprising results. * ElectroehemJ.cal ~ociety Active Member.

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