Effects of Abomasal Infusion of Conjugated Linoleic Acid on Milk Fat Concentration and Yield from Pasture-Fed Dairy Cows

Abstract

The aim of this study was to investigate the effects of conjugated linoleic acid supplementation on the synthesis of milk fat in pasture-fed Friesian cows. In four cows, a commercial mixture containing 62.3% (wt/vol) conjugated linoleic acid was infused intraabomasally to avoid rumen fermentation and biohydrogenation. The design was a 4 x 4 Latin square in which each cow received infusions of 0, 20, 40, and 80 g/d of conjugated linoleic acid mixture for 4 d. Cows were fed freshly cut ryegrass/white clover pasture ad libitum. Milk fat concentration was decreased by 36, 43, and 62% and milk fat yield was decreased by 32, 36, and 60% by the 20, 40, and 80 g of conjugated linoleic acid/d treatments. Dry matter intake, milk protein concentration, and protein yield were unaffected by treatments; however, milk yield was increased by 11% during the 40-g conjugated linoleic acid/d treatment. The effects of conjugated linoleic acid infusion were most pronounced in reducing de novo fatty acid synthesis and desaturation. Results show that the inhibitory effect of this conjugated linoleic acid mixture on milk fat synthesis occurs in pasture-fed cows, and demonstrate the potential to dramatically alter gross milk composition. This technology could offer a management tool to manipulate milk composition and energy demands of pasture-fed cows.

Effect of duodenal infusion of trans10,cis12-CLA on milk performance and milk fatty acid profile in dairy goats fed high or low concentrate diet in combination with rolled canola seed

“…In dairy cows, the decrease in the MFC and in the fat yield were largely related to a decrease in the yield and in the percentage of shortto medium chain saturated FA [2]. The highest decreases in short to medium-chain saturated FA were observed with the highest doses of t10,c12-C18:2 infused [7,8,26]. However, in our trial no effect on MFC was observed whatever the diet, probably because the synthesis of even-numbered saturated FA with 4 to 16 C was not decreased despite a high t10,c12-C18:2 concentration in milk fat.…”

“…Consequently, product to substrate ratios of c9-C14:1/C14:0, c9-C16:1/C16:0, c9-C18:1/C18:0, and c9,t11-C18:2/t11-C18:1 represent a desaturase index and they serve as a proxy for Δ 9 desaturase activity. In dairy cows, the infusion of a high dose [7,16,26] but not of a low dose [7,8,25] of t10,c12-C18:2 reduced desaturase indexes in milk fat. Baumgard et al [16] demonstrated that the mechanism by which t10,c12-C18:2 decreased these substrate to product ratios involves a reduction in the mRNA abundance of Δ 9 desaturase in the mammary gland.…”

Recent advances in the regulation of milk fat synthesis

“…Under certain marketing systems and management schemes, it may be advantageous to reduce milk fat yield , and in some feeding and management systems the reduction in milk fat yield has allowed for a repartitioning of nutrients to support increased milk and milk protein yield (e.g. Bernal-Santos et al, 2003;Mackle et al, 2003;Lock et al, 2006b;Odens et al, 2007). Producers may also find it advantageous to induce MFD during periods of limited feedstuff availability such as inadequate rainfall in pasture-based systems or for a short period while breeding.…”

Partial replacement of corn grain with calcium salts of fatty acid in the concentrate fed to grazing primiparous and multiparous dairy cows

“…In a previous study using the same source of cSFA fed to grazing cows, milkfat concentration was reduced (-26% in respect to the Control group) with no negative effect on NDF digestion (Schroeder et al 2003). In pasture-fed MC, milkfat concentration was decreased 43% by the abomasal infusion with 40 g day -1 of a clA mixture, reducing the energy requirements for lactation (13%) and increasing milk yield (11%; Mackle et al 2003).…”

“…Consequently, a reduction of milkfat synthesis by unsaturated FA supplementation may be potentially beneficial to grazing dairy cows in early lactation, increasing milk production or enhancing the energy balance of the cow (Mackle et al 2003). Thus, supplementing unsaturated FA may not only increase energy density in pasture-based diets but also reduce milkfat concentration, diverting energy to milk yield and/or body reserves recovery.…”