Essential oils examined for beef cattle rearing

Essential oils examined for beef cattle rearing

Ruminant nutritionists have been working to modulate the diverse populations of ruminal microorganisms with the goal of improving rumen efficiency. This objective can be reached

*The authors are with the department of health, animal science and food safety at the University of Milan in Italy.

CURRENTLY in beef cattle production, the goal is to pursue maximum production efficiency by limiting any kind of waste as much as possible.

In this view, rumen fermentation represents one of the main critical points on which it's possible to implement interventions to improve the cattle productivity. In fact, the polygastrics establish an essential relationship with the microorganisms in their rumen, providing them with nutrients through which these microorganisms proliferate, starting processes necessary to the ruminant itself, including fiber degradation, production of volatile fatty acids (VFAs) and synthesis of water-soluble vitamins and bacterial proteins of high biological value.

This synergy is, however, also characterized by a significant use of energy and nitrogen. In fact, the rumen fermentation of carbohydrates and proteins are accompanied by the loss of methane and nitrogen, respectively. The values stand at between 8% and 12% for digestible energy ingested by ruminants lost in form of methane, and between 75% and 85% for nitrogen, which is excreted in feces and urine daily, and consequently cannot be used for the processes of bacterial protein synthesis.

These energy losses not only reduce production performance but also contribute to the release of pollutants into the environment. The experts in nutrition have long been working to modulate the diverse populations of ruminal microorganisms with the goal of improving the energetic and protein efficiency in the rumen. This objective can be reached through a specific diet optimization, and by adding feed additives that can modify the rumen environment, inhibiting or stimulating specific microbial populations.

Ionophores in ruminant feed have been found contain the energetic and protein losses that characterize the ruminant digestion. However, the use of these products for animal nutrition has met growing disapproval from European consumers, because of the risk of the occurrence of antibiotic-resistance phenomena due to the presence of residues in products of animal origin. For this reason, their use has been permanently forbidden from the European Union, since January 2006 (Directive 1831/2003/CEE, European Commission, 2003).

Therefore, research has been directed toward the identification of active ingredients that are alternative to ionophore antibiotics for the modulation of rumen fermentation, such as yeasts, organic acids, plant extracts, prebiotics and probiotics, paying particular attention to the products of natural origin in line with the expectations of the modern consumer.

 

Essential oils

Plants produce a wide variety of organic compounds that do not seem to have a specific function for their development, but are indeed responsible for smell and color of plants, and perform important functions connected to the interaction with the surrounding environment and also, most interestingly, have a significant antifungal and antibacterial action.

These metabolites are classified into three main groups: saponins, tannins and essential oils.

Among these, the essential oils are assuming increasing importance in livestock nutrition for their multiple actions, such as, in particular, the improvement of ruminal efficiency and the reduction of wasted energy and the release of pollutant metabolites into the environment.

The Food & Drug Administration has declared essential oils safe in 2004 both for the animal and the human nutrition. They consist of a variety of substances of different nature and different functions.

Essential oils have a wide range of beneficial effects on health, such as positive effects on cardiovascular diseases, on the tumors, inflammatory processes and, more generally, in all those diseases in which free radicals are involved. In fact, these properties depend on their ability to inactivate free radicals, inhibit the peroxidation of lipid membranes, chelate metals and play a similar function as antioxidant enzymes. The main function of these compounds remains, however, the antiseptic and antimicrobial one.

Due to their antibacterial properties, essential oils are a valid alternative to the use of auxinic antibiotics in animal nutrition. Studies carried out on other species have demonstrated that the effect of plant extracts administered daily in the diet of pigs and poultry has led to an increase of weight comparable to the one obtained with the addition of ionophore antibiotics.

There are, however, few studies performed in vivo regarding the effects on rumen fermentation of feed addition of essential oils.

Despite the interesting and potential effects of essential oils in livestock production, the related scientific research, after a period of great activity in the early 1960s, has stopped over the next 30 years with the arrival of ionophore antibiotics as growth promoters.

As soon as the use of such substances as feed additives had been banned by the European Union, the study of the essential oil mechanisms of action in the rumen has revived, resulting, in the last 10 years, in lots of in vitro studies, about more than 25 different vegetal extracts (including Achillea millefolium, Arnica chamissonis, Betula alba, Dactylis glomerata, Eucalyptus globulus, Ginkgo biloba, Lavandula officinalis, Lespedeza capitata, Hypericum perforatum, Solidago virgaurea, Fagopyrum esculentum, Equisetum arvense, Salvia officinalis, Pimpinella anisum, Juniperus oxycedrus, Capsicum annuum, Cinnamonum cassia, Syzygium aromaticum, Anethum graveolens, Trigonella foenum graecum, Allium sativum, Zingiber officinale, Origanum vulgare, Melaleuca alternifolia and Armoracia rusticana).

To identify the most effective essential oils to be used in ruminant feed, attention should be directed primarily to those compounds able to select and stimulate the proliferation of rumen microflora, increasing the amount of propionate and reducing the production of acetate and methane, without altering the total amount of VFAs.

The essential oils that have proved in vitro a more active effect towards a positive and efficient modulation of rumen fermentation are garlic, cinnamaldehyde (the most important active compound of cinnamon), eugenol (active compound of the flowers not yet budded and dried of Eugenia caryophyllata, commonly called "cloves"), capsicum (the active compound of red pepper) and anethole (the active compound of anise oil).

From these studies, although conducted in vitro, emerged how the use of essential oils such as cinnamaldehyde, eugenol and capsicum in cattle feeding as modulators of rumen fermentation. This represents an innovative strategy due to their unique targeted antimicrobial activity, ability to increase VFA production and reduce ruminal ammonia nitrogen and methane production with a potential of significant importance both on the environmental impact and economic balance of livestock production.

Considering that there is limited information regarding the in vivo efficacy of essential oils specifically in beef cattle, a study was carried out to verify if their use was capable of improving the growth performance and health status of beef cattle. In addition of antimicrobial ability, essential oils have shown in in vitro studies interesting anti-inflammatory, antioxidant and immunostimulant properties that could be, therefore, an interesting aid in managing newly arrived beef calves.

 

Field trial

For this purpose, 45 newly received Charolaise beef cattle with an average weight of about 420 kg were divided, within few hours from their arrival from France, in two homogeneous groups fed with the same diet (Table 1) except for the addition in treated group of a mixture containing the combination of three essential oils of cinnamaldehyde, eugenol and capsicum in quantity of 0.8 g per head per day.

All animals were submitted upon arrival to vaccination against infective bovine rhinotracheitis (BHV1), parainfluenza-3 virus, respiratory syncytial virus, bovine viral diarrhea virus and to antiparasitic treatment with ivermectin. The booster vaccination was performed at day 25 only against BHV1. Each animal was weighed on days 0, 25, 53 and 117 to obtain its average daily gain (ADG). On days 0, 25 and 53, a blood sample was collected from 10 animals per group for the evaluation of some blood parameters indicators of the health status such as: titration of antibodies against BHV1 by serum neutralization test, serum bactericidal activity, haptoglobin and reactive metabolites of oxygen (ROMs).

The results show that essential oils of cinnamaldehyde, eugenol and capsicum in beef cattle diet improve growth performance and immune reactivity during the adaptation phase after transport. In fact, treated cattle showed better growth performances than controls with a significantly greater ADG of about 130 g per head per day during the first 53 days and a total of about 90 g per head per day during the whole finishing period (Figure).

The growth improvement can be explained by the optimization of the digestive process induced by essential oils, with an improvement in fermentation activities at ruminal level and specifically with reduction of methanogenesis and energy waste, increase microbial protein production and reduction of ammonia concentrations.

In this regard, it is noted that essential oils have proved to be more effective precisely in beef cattle raised in intensive management systems, since the antimicrobial effect of essential oils is greater in a ruminal pH range between 5.5 and 6.0, conditions that characterize diets of imported beef cattle for finishing.

Regarding the immune response, the administration of essential oils has contributed to a more rapid return to physiological conditions after the stressful event of transport (Table 2).

The serum bactericidal activity at day 25 was found to be higher than the desired threshold of 90% and reported in the literature as physiological in healthy cattle. The immune response to vaccination was also higher. These positive effects, in addition to being the consequence of a functional rumen that was in excellent condition with a consequent increase in dry matter intake, may also result from a direct effect of essential oils on the immune system cells through mechanisms of action that have yet to be investigated.

The concentration of serum haptoglobin, an indicator of the presence of an inflammatory response, has not shown variations between the groups, probably due to the absence of an impairment of the animal health conditions such to induce a representative production and release of inflammatory proteins.

Even with regard to ROMs, a parameter characterized by high sensitivity to numerous factors and for this reason often difficult to interpret, there were no differences between treated animals and controls.

In conclusion, results of the present study showed that the use of essential oils of eugenol, cinnamaldehyde and capsicum seems to be a good strategy both to encourage a more rapid end of the negative effects due to the stress of adaptation phase and for the improvement of growth performance in the finishing stages of beef cattle production with potential positive effects also in terms of environmental impact.

 

1. Composition and diet characteristics (kg/head)

 

Arrival (first 30 days)

Finishing

Corn silage

4.0

6.0

Corn

2.0

3.0

Dry beet pulps

1.2

1.5

Soybean meal (44% CP)

0.7

1.0

Wheat bran

0.5

0.8

Wheat straw

1.4

0.6

Vitamin and mineral supplement

0.2

0.2

As fed, kg

12.6

16.9

Dry matter, kg

8.3

10.8

Mj, kg/DM

1.53

1.65

CP, % DM

12.71

14.11

NFC, % DM

40.53

45.85

NDF, % DM

38.68

31.57

peNDF, % DM

27.89

19.12

Starch, % DM

29.63

34.15

Fat, % DM

2.89

3.05

Calcium, % DM

0.68

0.75

Phosphorus, % DM

0.31

0.34

 

2. Results of blood parameters

Parameter

Day

Control

Treated

P

Serum neutralization (log10(dilution))

0

0

0

25

0.57

0.81

0.04

53

0.90

1.02

0.02

Serum bactericidal (%)

0

87

91

25

87

92

0.01

Haptoglobin (mg/mL)

0

0.36

0.10

25

0.13

0.14

NS

ROMs (mmol hydrogen peroxide)

0

1.28

1.22

25

1.54

1.44

NS

 

Volume:85 Issue:31

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