Increasing dietary levels of docosahexaenoic acid-rich microalgae: Ruminal fermentation, animal performance, and milk fatty acid profile of mid-lactating dairy cows

Abstract

This study aimed to evaluate the effects of increasing dietary levels of microalgae (ALG), rich in docosahexaenoic acid (DHA; All-G-Rich, Alltech, Nicholasville, KY), in isolipidic diets, on animal performance, nutrient digestibility, ruminal fermentation, milk fatty acid profile, energy balance, microbial protein synthesis, and blood serum metabolites in mid-lactating dairy cows. Twenty-four Holstein cows [130.3 ± 15.4 d in milk, and 30.8 ± 0.543 kg/d of milk yield (mean ± standard error)] were used in a 4 × 4 Latin square design experiment to evaluate the following treatments: control diet, without addition of ALG; and increasing levels of ALG [2, 4, and 6 g/kg of dry matter (DM)]. The ALG decreased DM intake and increased total-tract DM apparent digestibility. A tendency was observed for a quadratic effect on total-tract NDF digestibility by ALG inclusion, with peak value of the quadratic response at 4.13 g/kg of DM dose. Moreover, ALG increased ruminal pH and decreased acetate and total volatile fatty acid concentrations. Fat-corrected milk and energy-corrected milk were quadratically affected, and a tendency for a milk yield effect was observed when ALG levels increased, whereas maximal yields were observed with intermediate doses. Milk fat, protein, and lactose concentrations were diminished, whereas productive efficiency was improved by the increase of ALG levels. Saturated fatty acid proportions were decreased, whereas polyunsaturated fatty acid proportions were increased when ALG was fed. There was low DHA transfer into milk; however, ALG inclusion decreased C18:0, C18:1 cis-9, C18:2 cis-9,12, and C18:3 cis-9,12,15 proportions, and increased C18:2 cis-9,trans-11, C18:1 trans-9, and C18:1 trans-11 proportions. Gross energy intake was decreased, whereas no effect was observed on digestible, metabolizable, or net energy intake. The ALG inclusion quadratically affected the microbial protein synthesis, with maximal enhancement at 3.24 g/kg of DM dose, and also increased serum cholesterol concentration. Under the conditions of this experiment, the inclusion of ALG in diets for mid-lactating dairy cows decreased feed intake and increased nutrient digestibility, improving productive efficiency and modifying milk fatty acid profile. Estimated intermediate doses (1.22 to 2.90 g/ kg of DM) of DHA-rich ALG may be beneficial to milk, fat-corrected milk, and energy-corrected milk yields, and is recommended for dairy cows.

Advances in fatty acids nutrition in dairy cows: from gut to cells and effects on performance

“…Cows were fed with different lipid sources, most of them UFA that promoted a shifts in the rumen biohydrogenation process and thereby increasing intermediate byproducts (i.e., CLA and trans-11 C18:1), and decreasing SFA (i.e., C16:0 and C18:0). Marine feedstuffs such as fish oil and microalgae have strong impacts on rumen biohydrogenation that often leads to increase in some trans C18:1 and CLA [322,325]. Dietary vegetable oils such as soybean oil often leads to changes in ruminal microbial populations and shifts in ruminal fermentation parameters affecting cellulolytic bacteria such as Fibrobacter succinogenes, Ruminococcus flavefaciens, Ruminococcus albus and Butyrivibrio fibrisolvens that are important in the biohydrogenation process of PUFA [342].…”

Long term dietary supplementation with microalgae increases plasma docosahexaenoic acid in milk and plasma but does not affect plasma 13,14-dihydro-15-keto PGF2α concentration in dairy cows

“…The primary objective of this study was to determine the long-term effects of feeding microalgae that is high in C22:6 n-3 on milk and plasma fat concentration of LC n-3 PUFA and animal performance over time. The cows were fed 100 g of microalgae per d as higher inclusion levels have been shown to reduce DM intake and/or result in milk fat depression (Vanbergue et al ., 2018; Marques et al ., 2019), with the consequence of a reduced milk and/or fat yield. In the current study there was no effect of dietary treatment on DM intake, which averaged 22.1 kg/d over the 14 week period.…”

Alternative and Unconventional Feeds in Dairy Diets and Their Effect on Fatty Acid Profile and Health Properties of Milk Fat

“…Therefore, the addition of marine-derived supplements seems to be an efficient method of producing n3 PUFA-enriched milk. The results of some studies (e.g., [ 8 , 84 , 85 ]) have shown that the inclusion of microalgae in the diet of dairy cows can affected the FA profile of their milk, mainly in the content of rumenic acid and n3 FAs, the n6/n3 ratio, and the transfer efficiency of DHA from the diet into milk fat. However, in [ 86 ] it was observed that changes in milk fat composition depend on the dose of algal supplementations, e.g., graduated doses of microalgae that are rich in DHA in the diets of dairy cows resulted in reduced SFA content, whereas the proportion of PUFAs, C18:2cis9t11, and other FAs were significantly increased [ 84 ].…”

“…The results of some studies (e.g., [ 8 , 84 , 85 ]) have shown that the inclusion of microalgae in the diet of dairy cows can affected the FA profile of their milk, mainly in the content of rumenic acid and n3 FAs, the n6/n3 ratio, and the transfer efficiency of DHA from the diet into milk fat. However, in [ 86 ] it was observed that changes in milk fat composition depend on the dose of algal supplementations, e.g., graduated doses of microalgae that are rich in DHA in the diets of dairy cows resulted in reduced SFA content, whereas the proportion of PUFAs, C18:2cis9t11, and other FAs were significantly increased [ 84 ]. In [ 8 ], the n3 FA levels were higher in microalgae-supplemented cows compared to controls, and [ 79 ] reported increased levels of DHA in the milk of cows fed a silage-based diet with microalgae supplementation.…”