Citrus Pulp as a Dietary Source of Antioxidants for Lactating Holstein Cows Fed Highly Polyunsaturated Fatty Acid Diets

Abstract

The effects of feeding pelleted citrus pulp (PCP) as a natural antioxidant source on the performance and milk quality of dairy cows fed highly polyunsaturated fatty acid (FA) diets were evaluated. Four lactating Holstein cows were assigned to a 4×4 Latin-square. Treatments, on a dry matter (DM) basis, were i) control diet; ii) 3% soybean oil; iii) 3% soybean oil and 9% PCP and; iv) 3% soybean oil and 18% PCP. When cows fed on citrus pulp, the DM intake tended to decrease. The total tract apparent digestibility of DM and ether extract decreased when cows fed on the control diet compared to other diets. Cows fed PCP had higher polyphenols and flavonoids content and higher total ferric reducing antioxidant power (FRAP) in milk compared to those fed no pelleted citrus pulp. Cows fed 18% PCP showed higher monounsaturated FA and lower saturated FA in milk fat compared with cows fed the other diets. The lowest n-6 FA proportion was in milk fat from cows fed control. The present study suggests that pelleted citrus pulp added to 9% to 18% DM increases total polyphenols and flavonoids concentration, and the FRAP in milk.

Effect of the inclusion of fresh lemon pulp in the diet of lactating ewes on the properties of milk and cheese

“…These results can be related to the intake of FLP polyphenols, which would have partially inhibited the PUFA biohydrogenating activity of ruminal microorganisms, and promoted the formation of biohydrogenation intermediates such as the VA, as also suggested by Santos et al (2014) and Santos-Silva et al (2016). On the other hand, Lanza et al (2015) fed lambs increasing concentrations of dried citrus pulp to raise the intake of both unsaturated FAs and phenolic compounds as a means of reducing the rate of PUFA biohydrogenation in the rumen; accordingly, they improved intramuscular FA composition, particularly due to the higher content of RA.…”

“…The most interesting finding is the FLP's high phenol content: it was 8-10 times higher than other data reported in the literature (Ramful et al, 2011;Santos et al, 2014). Most of the polyphenols in citrus fruits, as well as in FLP, consist of flavonoids, which are potent antioxidant compounds with anticancer, antiatherogenic, antimicrobial and anti-inflammatory properties (Tripoli et al, 2007); thus, FLP is also a potentially healthy food.…”

“…Supplementation of ruminant diets with citrus pulp may improve N utilisation (Kim et al, 2007;Piquer et al, 2009), reducing the ruminal NH 3 -N escape and, consequently, the milk urea level; several studies support this hypothesis, both in dairy cows (Santos et al, 2014) and in dairy ewes . Nevertheless, the present study found the opposite, since the milk from the FLP ewes had higher urea content than the milk from the control group.…”

“…Because citrus pulp contains high levels of unsaturated FAs and phenolic compounds (Bampidis and Robinson, 2006), it would be reasonable to expect a change in the ruminal biohydrogenation pathway, and then in the bioavailability of unsaturated long-chain FAs for milk fat synthesis within the mammary gland. Nevertheless, recent studies have reported that feeding lactating cows pelleted citrus pulp (Santos et al, 2014) or replacing cereals fed to dairy ewes with dried citrus pulp supplemented with vegetable oil (Santos-Silva et al, 2016) alters the long-chain FA profile very little in milk. In agreement with those results, the inclusion of FLP in the diet of ewes in the present study affected the milk FA profile, but only weakly, with few significant differences but clear trends.…”

“…There is a shortage of information regarding the effect of dietary citrus pulp on milk or cheese antioxidants in dairy cattle or ewes; to date, only one paper has reported on the enrichment of polyphenols and flavonoids and the increase in the antioxidant capacity in milk of dairy cattle fed with a diet with 18% of pelleted citrus pulp (Santos et al, 2014). Moreover, a strong positive correlation between polyphenols and antioxidant capacity, expressed as TEAC (r = 0.95) or ferric reducing antioxidant power (r = 0.73), was reported by Ramful et al (2011).…”