Milk Composition and Apparent Digestibilities of Dietary Fatty Acids in Lactating Dairy Cows Abomasally Infused with Cis or Trans Fatty Acids

Abstract

Fat supplementation of diets for dairy cows produces changes in nutrient supply and milk composition. The effect of abomasal infusion of either cis-C18:1 or trans-C18:1 fatty acid isomers on the digestibility of fatty acids and milk composition was determined in lactating dairy cows. Six multiparous midlactation Holstein cows were used and fed a control diet containing 50% forage and 50% concentrate. Treatments were (per day): no infusion, infusion of a 630-g fat mixture high in cis-C18:1 isomers, and infusion of a 623-g fat mixture high in trans-C18:1 isomers using two 3 x 3 Latin squares with 4-wk experimental periods. Fat infusion did not affect total dry matter intake and increased apparent digestibilities of total fatty acids. Apparent digestibilities of C18 fatty acids were directly related to the number of double bonds within isomers, and cis-C18:1 isomers were slightly more digestible than trans-C18:1 isomers. The lower yield of C12:0, C14:0, and C16:0 fatty acids in milk fat and higher milk citrate observed when cows were infused with trans-C18:1 suggests a depressed de novo milk fatty acid synthesis. Effects of trans infusion on milk fat were independent of ruminal fermentation, fatty acid apparent absorption, and fatty acid plasma concentrations. Lower milk protein yield in cows infused with fat may have been caused by a decrease in milk protein synthesis.

Effect of fatty acid calcium salts from linseed oil on the yield and n-3 fatty acid content of milk and on blood plasma parameters of cows

“…Similar results were obtained after duodenal infusion of fatty acids (Romo et al, 2000). In some studies, such infusion was accompanied by a decrease in the N-casein fraction of milk (DePeters et al, 1989).…”

“…Chouinard et al (1997), who gave cows with an average yield of 34.5 kg milk/day, rations containing 2 or 4% (447 or 894 g/day) CSFA from canola oil, did not find significant differences in the milk yield, only a slight downward tendency. In later studies, Romo et al (2000) found that the milk yield of cows is significantly differentiated not by the amount of fodder fat, but by the geometric form of the fatty acids. By giving duodenal infusions of cis-type acids compared with trans acids, they increased their yield by about 4 kg of milk, with an increase in milk fat of 0.18 pcrcentage units and a decrease in milk protein of 0.24 percentage units.…”

Inclusão de fontes de óleo na dieta de cabras em lactação: produção, composição e perfil dos ácidos graxos do leite

“…Contudo, as concentrações dos ácidos capróico (6:0), caprílico (8:0), cáprico (10:0), láurico (12:0), mirístico (14:0), pentadecílico (15:0), palmítico (16:0) e margárico (17:0) na gordura do leite reduziram (P<0,09) com a inclusão de óleos Tabela 5 -Composição percentual dos ácidos graxos na gordura do leite de cabras Saanen alimentadas com dietas acrescidas de diferentes fontes de óleo Romo et al (2000), em vacas, a infusão abomasal de uma mistura de isômeros cis e trans do C18:1 resultou na síntese de gordura do leite com menores proporções do C14:0, C14:1, C16:0 e C16:1. A concentração de ácido palmítico (Tabela 5) no leite das cabras foi maior (P<0,09) com a suplementação com óleo de arroz (24,5%) que com óleos de oleaginosas (20,68%).…”

Feeding micronized and extruded flaxseed to dairy cows: Effects on digestion and ruminal biohydrogenation of long-chain fatty acids

“…Effects of fat supplementation on total tract digestibility of LCFA are inconsistent. Feeding supplemental fat to dairy cows increased (Klusmeyer and Clark 1991;Romo et al 2000), decreased (Tice et al 1994;Hussein et al 1996) or had no effect (Wu et al 1991;Kalscheur et al 1997) on apparent total tract digestibility of individual FA.…”

“…Fatty acid digestibility is thought to increase with the degree of unsaturation (Doreau and Ferlay. 1994;Romo et al 2000). Borsting et al (1992) indicated that triglyceride synthesis, which is an essential step for lipid absorption in the epithelial cell of the small intestine, is positively related to the degree of unsaturation of FA.…”