Milk fatty acids: Mammary synthesis could limit transfer from duodenum in cows

Milk fat: opportunities, challenges and innovation

Milk fat is a high-value milk component that is processed mainly as butter, cheese, cream and whole milk powder. It is projected that approximately 35 million tonnes of milk fat will be produced globally by 2025. This surplus, enhances the need for diversification of milk fat products and the milk pool in general. Infant milk formula producers, for instance, have incorporated enzyme modified ("humanised") milk fat and fat globule phospholipids to better mimic human milk fat structures. Minor components like mono- and di-glycerides from milk fat are increasingly utilized as emulsifiers, replacing palm esters in premium-priced food products. This review examines the chemistry of milk fat and the technologies employed for its modification, fractionation and enrichment. Emerging processing technologies such as ultrasound, high pressure processing, supercritical fluid extraction and fractionation, can be employed to improve the nutritional and functional attributes of milk fat. The potential of recent developments in biological intervention, through dietary manipulation of milk fatty acid profiles in cattle also offers significant promise. Finally, this review provides evidence to help redress the imbalance in reported associations between milk fat consumption and human health, and elucidates the health benefits associated with consumption of milk fat and dairy products.

Cobalt reduces the Δ⁹-desaturase index of sow milk

The main objective of this study was to examine if cobalt (Co) reduces Δ(9) -desaturase indices in milk and blood lipids in sows. The experimental design consisted of a repeated measurement consisting of a pre-treatment period of a minimum of 9 days, a treatment period of 5 days and a post-treatment period of 6 days. Experimental animals consisted of 10 lactating sows; five sows had an intramuscular injection of 59 mg Co diluted in 5 ml 0.9% saline solution twice a day, whereas the other five had an intramuscular injection of 5 ml 0.9% saline solution twice a day as a control. Milk Δ(9) -desaturase indices for cis-9 18:1, cis-9 16:1 and cis-9 14:1 were significantly reduced (p < 0.0001) as a result of the Co-treatment, contrasting with the plasma Δ(9) -desaturase indices, which were unaffected. Potential mechanisms explaining how Co might reduce milk Δ(9) -desaturase indices are discussed. Moreover, the toxicological level of Co and potential implications of using Co-ethylenediaminetetraacetic acid as a liquid marker in digestibility experiments are addressed.

Effect of dietary starch or micro algae supplementation on rumen fermentation and milk fatty acid composition of dairy cows

Two experiments with rumen-fistulated dairy cows were conducted to evaluate the effects of feeding docosahexaenoic acid (DHA; C22:6 n-3)-enriched diets or diets provoking a decreased rumen pH on milk fatty acid composition. In the first experiment, dietary treatments were tested during 21-d experimental periods in a 4 x 4 Latin square design. Diets included a control diet, a starch-rich diet, a bicarbonate-buffered starch-rich diet, and a diet supplemented with DHA-enriched micro algae [Schizochytrium sp., 43.0 g/kg of dry matter intake (DMI)]. Algae were supplemented directly through the rumen fistula. The total mixed ration consisted of grass silage, corn silage, soybean meal, and a standard or glucogenic concentrate. The glucogenic and buffered glucogenic diet had no effect on rumen fermentation and milk fatty acid composition because, unexpectedly, no reduced rumen pH was detected. The algae diet had no effect on rumen pH but provoked decreased butyrate and increased isovalerate molar proportions in the rumen. In addition, algae supplementation affected rumen biohydrogenation of linoleic and linolenic acid as reflected in the modified milk fatty acid composition toward increased conjugated linoleic acid (CLA) cis-9 trans-11, CLA trans-9 cis-11, C18:1 trans-10, C18:1 trans-11, and C22:6 n-3 concentrations. Concomitantly, on average, a 45% decrease in DMI and milk yield was observed. Based on these drastic and impractical results, a second animal experiment was performed for 20 d in which 9.35 g/kg of total DMI of algae were incorporated in the concentrate and supplemented to 3 rumen-fistulated cows. Algae concentrate feeding increased rumen pH, which was associated with decreased rumen short-chain fatty acid concentrations. Moreover, a different shift in rumen short-chain fatty acid proportions was observed compared with the first experiment because molar proportions of butyrate, isobutyrate, and isovalerate increased, whereas acetate molar proportion decreased. The milk fatty acid profile changed as in experiment 1. However, the decrease in DMI and milk yield was less pronounced (on average 10%) at this algae supplementation level, whereas milk fat percentage decreased from 47.9 to 22.0 g/kg of milk after algae treatment. In conclusion, an algae supplementation level of about 10 g/kg of DMI proved effective to reduce the milk fat content and to modify the milk fatty acid composition toward increased CLA cis-9 trans-11, C18:1 trans, and DHA concentrations.

Effect of plant oils in the diet on performance and milk fatty acid composition in goats fed diets based on grass hay or maize silage

Based on the potential benefits to long-term human health there is interest in developing sustainable nutritional strategies for reducing saturated and increasing specific unsaturated fatty acids in ruminant milk. The impact of plant oil supplements to diets containing different forages on caprine milk fatty acid composition was examined in two experiments using twenty-seven Alpine goats in replicated 3 x 3 Latin squares with 28 d experimental periods. Treatments comprised of no oil (control) or 130 g/d of sunflower-seed oil (SO) or linseed oil (LO) supplements added to diets based on grass hay (H; experiment 1) or maize silage (M; experiment 2). Milk fat content was enhanced (P<0.01) on HSO, HLO and MLO compared with the corresponding H or M control diets, resulting in 17, 15 and 14% increases in milk fat secretion, respectively. For both experiments, plant oils decreased (P<0.05) milk 10:0-16:0 and odd- and branched-chain fatty acid content and increased 18:0, trans-Delta(6-9,11-14,16)-18:1 (and their corresponding Delta-9 desaturase products), trans-7, trans-9-conjugated linoleic acid (CLA), trans-9, trans-11-CLA and trans-8, cis-10-CLA concentrations. Alterations in the distribution of cis-18:1, trans-18:1, -18:2 and CLA isomers in milk fat were related to plant oil composition and forage in the diet. In conclusion, plant oils represent an effective strategy for altering the fatty acid composition of caprine milk, with evidence that the basal diet is an important determinant of ruminal unsaturated fatty acid metabolism in the goat.