26 March 2013

6 minute read

Introduction

Grazing may provide ruminants with health benefits from certain vitamins and minerals. Though fresh forages are typically considered capable of supplying adequate levels of antioxidants for dairy cattle, the availability of these compounds for lactating grazing cows is diminished when pasture availability is not adequate to meet their energy requirements.

In this situation, the gap between energy required for milk production and energy intake is often met by supplementing cows with conserved forages like silage. Silage is known for its poor content in antioxidants and thus might expose cows to oxidative stress.

Evaluation of oxidative stress in ruminants is contributing significantly to understanding of the fundamental processes involved in metabolic disorders. Oxidative stress is believed to play an important role in the regulation of the metabolic activity of some organs and productivity in farm animals (Celi, 2011b).

However, it is not clear whether or not the level of oxidative stress during the peripartum period could compromise animal performance. Milk production is associated with oxidative stress and, therefore, supplementation of cows’ diets with antioxidants might result in an improvement of their oxidative status and productive performances.

Main Messages

• Yerba mate supplementation results in lower degree of oxidative stress.
• Oxidative stress biomarkers – reactive oxygen metabolites (ROMs) and biological antioxidant potential (BAP) – can be considered as new and reliable indicators of animal welfare.
• Yerba mate supplementation of diet of dairy cows improves their productive and reproductive performances.
• The use of alternative feedstuff like yerba mate in dairy nutrition represents a novel management procedure that can increase farms profits and is extremely easy to use.

Yerba Mate

Ilex paraguariensis, from the Aquifoliaceae plant family, is a native South American tree used for the production of yerba mate tea (Heck and de Mejia, 2007; Bracesco et al., 2011). Research on the biomedical properties of this herb had a late start and lags well behind the impressive amount of literature on green tea and coffee, which is also a reflection of the different economic development and sizes of the populations consuming the latter.

However, in the past 15 years, there has been a several-fold increase in the literature on Ilex paraguariensis showing antioxidant properties using chemical models and ex vivo lipoprotein studies; vasodilating and lipid reduction properties; and weight reduction properties, among others.

Several active phytochemicals have been identified in yerba mate that may be responsible for its health benefits. These are polyphenols (chlorogenic acid) and xanthenes (caffeine and theobromine), purine alkaloids (caffeic acid, 3, 4-dicaffeolyquinic acid, 3, 5-dicaffeoylquinic acid), flavonoids (quercetin, kaempferol and rutin), amino acids, minerals (P, Fe and Ca) and vitamins (C, B1 and B2).

The main polyphenol identified in yerba mate is chlorogenic acid. The polyphenol concentration of mate has shown a strong correlation to its overall antioxidant capacity. Yerba mate has higher polyphenol concentration than green tea which correlates to its higher antioxidant capacity and its higher inhibition of free radicals than green tea.

Polyphenolic compounds found in mate tea differ significantly from green tea because mate tea contains high concentrations of chlorogenic acid and no catechins. On average, the amount of polyphenols extracted from yerba mate is 92 mg equivalents of chlorogenic acid per gram of dry leaves (Heck and de Mejia, 2007).

Polyphenols are efficient scavengers of free radicals in a number of in vitro systems and while this has been reported in several in vitro studies, there are little in vivo animal studies regarding the effects of the polyphenols contained within yerba mate with respect to their impact on exogenous antioxidant enzyme activity.

Yerba Mate Supplementation in Dairy Cows

The effect of yerba mate supplementation on dairy cows’ milk yield and oxidative stress was tested during mid-lactation (Experiment 1) and the dry period (Experiment 2). The yerba mate used in both experiments was organically grown in Paraguay. The content of the packs were pelleted immediately before the beginning of each experiment and stored in feed bins.

Conclusion

Our studies indicate that supplementation of dairy cows’ diet with yerba mate during mid-lactation and the dry period seems to improve milk yield, cow welfare and fertility. The observation that AOPP concentration significantly increased after the cows were fed maize silage is highly relevant because a high level of AOPP could indicate the presence of an inflammatory process which can compromise correct embryonic development in dairy cows (Celi et al., 2011).

The study of the environmental and nutritional factors that affect the oxidative status in ruminants is an interesting area of research and there is a growing body of evidence underpinning the pathophysiological consequences of oxidative stress in farm animals.

Although oxidative stress has been associated with numerous conditions, much remains to be discovered about its role in ruminant health and production. Clarity of understanding of the pathophysiology of oxidative stress in ruminants will make it possible to design specific antioxidant interventions.

The availability and efficient use of the feed resources are the primary drivers of animal performance. Feed security is essential to maximize productivity. Several agricultural and industrial by-products and forest products have been tested as potential sources of feeds for livestock and tea waste is one of them. The by-product from tea leaf, otherwise known as spent tea leaf, may be used as an alternative feed resource for ruminants.

Considering the large-scale production of yerba mate in South America, green tea in Australia and worldwide (Asia and Africa – especially in developing countries) and the availability of its waste (spent tea leaves), it is clear that there is a great opportunity to make intensive use of the available biomass from agro-industrial by-products (spent tea leaves) and other non-conventional feed resources (yerba mate and green tea).

There are many companies using the tea leaves for production of coffee, tea and other drinks. They produce large quantities of chaff, which is often burnt. Apart from losing the economic value of the waste, a huge amount of capital is expended in disposing it. In some places, the waste might constitute an environmental hazard through indiscriminate dumping and incineration.

However, the by-product could be utilized by ruminants, which are capable of converting fibrous feed into human edible food in the form of milk and meat. By converting tea waste products into animal feed, farmers can utilize resources not used in the production process and promote environmental conservation and a recycling-friendly livestock industry. Therefore, the use of alternative feedstuff like green tea, in dairy nutrition represents a novel management procedure that increases farms profits and is extremely easy to use.

Further Reading You can view the full report by clicking here.

March 2013