Alimentação de touros com própolis ou óleos essenciais (caju e mamona): desempenho, digestibilidade e contagem de células sanguíneas

Keywords: antioxidants, biodiesel, cattle, co-products, feedlot, plant oils.

Resumen

Antecedentes: en los sistemas de producción ganaderos, los antibióticos son añadidos a los bovinos para prevenir enfermedades y perturbaciones metabólicas y mejorar la eficacia alimenticia. Se han realizado considerables esfuerzos para desarrollar aditivos alternativos a los antibióticos. Objetivo: evaluar el efecto de los propóleos o aceites de anacardo y ricino sobre los índices productivos, ingestión de alimentos, digestibilidad y células sanguíneas de toros jóvenes. Métodos: los toros fueron mantenidos en un sistema de cebo intensivo durante 49 días. A partir del día 40, se tomaron muestras de heces durante cinco días para estimar la digestibilidad (utilizando como marcador la materia seca indigerible). Los toros fueron alimentados con una dieta de control (CON) con ensilaje de sorgo (41% de DM) y maíz triturado, harina de soja, glicerina, piedra caliza y sal mineral. El grupo suplementado con propóleos (PRO) recibió 3 g/animal/d en el concentrado. El grupo suplementado con los aceites esenciales (OIL) recibió 3 g/animal/d (1,5 g de anacardo + 1,5 g de aceite de ricino) añadido al concentrado. Resultados: el peso corporal final, promedio de ganancia diaria y eficacia alimenticia fueron mejores para los toros jóvenes alimentados con la dieta OIL. Los propóleos o aceites esenciales no tuvieron efecto sobre el consumo de alimento y digestibilidad. No hubo efecto de propóleos o la adición de aceites esenciales en las dietas con respecto a los valores medios de las células sanguíneas. El número de células rojas sanguíneas fue mayor en el último día de experimento, mientras que el número de células blancas sanguíneas fue menor. Conclusiones: la adición de propóleos en la dieta de los toros jóvenes no tuvo efecto ni en el desempeño ni la eficiencia alimenticia. La adición de aceites esenciales mejoró el desempeño animal. La ingestión de alimentos, digestibilidad y las células sanguíneas fueron similares en todos los tratamientos.

Palabras clave: aceites de plantas, antioxidante, biodiesel, bovino, cebadero, co-productos.

Resumo

Antecedentes: no sistema de produção de bovinos, os antibióticos são fornecidos aos bovinos para prevenir doenças e perturbações metabólicas e melhorar a eficiência alimentar. Consideráveis esforços têm sido realizados para desenvolver produtos alternativos aos antibióticos. Objetivo: avaliar o efeito de produtos alternativos: própolis, óleos de caju e mamona no desempenho animal, ingestão de alimentos, digestibilidade e células sanguíneas de toros jovens. Métodos: os animais foram confinados durante 49 dias. No quadragésimo dia de confinamento, as fezes foram amostradas por cinco dias para determinar a digestibilidade (matéria seca indigestível foi usada como indicador). Os animais foram alimentados com uma dieta controle (CON) com silagem de sorgo (41% da matéria seca) e milho moído, farelo de soja, glicerina, calcário e sal mineral. O grupo própolis (PRO) recebeu 3 g/animal/d dieta. O grupo com óleos essenciais (OIL) receberam 3 g/animal/d (1,5 g de óleo de mamona + 1,5 g de óleo de caju) na dieta. Resultados: o peso final, o ganho médio diário e a eficiência alimentar foram melhores para os animais alimentados com a dieta OIL. Própolis ou óleos essenciais não tiveram efeito na ingestão de alimentos e digestibilidade aparente. Não houve efeito de própolis ou dos óleos essenciais na dieta nos valores de células sanguíneas. A concentração de células vermelhas foi maior no último dia do experimento, enquanto que a concentração de células brancas foi menor. Conclusões: a adição de própolis na dieta dos animais em sistema intensivo de produção não teve efeito sobre o desempenho animal e eficiência alimentar. A adição de óleos essenciais melhorou o desempenho animal. A ingestão de alimentos, digestibilidade e células sanguíneas foram similares em todos os tratamentos.

Introduction

In Brazil, grazing is the system used for raising beef cattle (Ferraz and Felício, 2010). It, therefore, becomes crucial to evaluate technological alternatives capable of increasing efficiency of the industry and, consequently, restructuring the beef production chain. Thus, due to increases in the consumption of beef and the demand for quality products by consumers in Brazil, finishing cattle in feedlots may be a tool to maximize production and improve meat quality (Prado et al., 2008; 2012; Rotta et al., 2009). In Brazil, bulls are finished in feedlots when they reach 380 Kg body weight (BW) at about 24 months of age (Maggioni et al., 2009; Rotta et al., 2009). There has been an increase in using feedlot systems for finishing young bulls at 18 months (Dian et al., 2010; Ito et al., 2010) and bulls after weaning at 10 and 12 months of age (Ito et al., 2012). However, to maximize production efficiency of bulls finished in feedlots it is necessary to use diets with high energy density (NRC, 2000). To increase the energy density of the diet, it is necessary to use carbohydrate-rich cereals and co-products from the agri-food system (Marques et al., 2000). Carbohydrates degrade rapidly, which can disturb ruminal fermentation (Giger-Reverdin et al., 2002; Martins et al., 1999). Therefore, some substances have been used to control ruminal fermentation, including antibiotics and other compounds (Zawadzki et al., 2011). However, in recent years, public concern over routinary use of antibiotics in livestock nutrition has increased due to the emergence of antibiotic-resistant bacteria that may represent a risk to human health (Russell and Houlihan, 2003). Consequently, considerable effort has been devoted towards developing alternatives to antibiotics (Benchaar et al., 2008; Valero et al., 2011). Propolis and plant extracts offer an interesting opportunity in this regard ( Zhang et al., 2010; Zawadzki et al., 2011).

Natural plant extracts contain a wide variety of compounds with different functions and mechanisms of action (Benchaar et al., 2008; Zhang et al., 2010). Phenolic compounds, terpenoids, essential oils, and polyacetylenes are among the plant compounds that have antimicrobial characteristics, all of which have particular mechanisms of action (Zhang et al., 2010). Many plants produce secondary metabolites, which have properties to modulate ruminal fermentation (Benchaar et al., 2008). Natural plant extracts and propolis have compounds –e.g. phenol- with bioactive properties such as anti-inflammatory, antioxidant, antiviral, and antiparasitic (Fischer et al., 2008). Data on the effects of essential oils and their compounds on beef cattle performance are almost non-existent.

The aim of this study was to evaluate the effect of adding propolis or plant oils to the diets of growing bulls reared in an intensive system with corn and glycerine as energy sources on their performance, apparent digestibility and blood cell counts.

Material and methods

Ethical considerations

Thirty crossbred bulls (½ Aberdeen Angus, ½ Nellore) were used in a completely randomized design. Bulls were weighed and distributed into three diet groups with ten replications per group. Initial BW was 321 ± 27 Kg, with initial age of 18 ± 2 months old. Bulls were housed in individual pens on concrete floors with 10 m²/bull, equipped with feeders (60 cm deep and 2 m in length) and drinkers with a capacity of 250 L of water. The chemical composition of the feed is presented in Table 1.

The composition of diets is shown in Table 2. The intake of concentrate and sorghum silage was recorded daily until day 49 of the experimental period when bulls reached 387 ± 10.7 Kg BW.

Glycerine was produced in a soy-diesel facility (BIOPAR, Rolândia, Paraná, South of Brazil). The propolis product contains 0.054 mg/g total flavonoids in chrysin. The essential oils contain ricinoleic acid, anacardic acid, cardanol, and cardol. Ricinoleic acid was obtained from castor oil (extracted from castor seeds). Anacardic acid, cardanol, and cardol were obtained from cashew nut shell liquid (from the processing of cashew nuts).

Bulls were randomly assigned to one of three diets: CON – Control, PRO – propolis addition, and OIL – essential oils addition. Bulls were fed twice a day at 08:00 and 16:00 h. The diet formulation was designed to provide 1.4 Kg/d body weight gain, according to the NRC (2000) recommendations.

Daily feed intake was estimated as the difference between supplied feed and orts. Feed and orts samples were collected during the collection period and a representative composite sample was drafted per animal in each treatment. Bulls were weighed at the beginning of the experiment and every 14 days (after fasting from solid feed for 16 hours) for the duration of the experiment to determine performance (49 days).

Indigestible dry matter (iDM) was used as an internal marker to estimate fecal DM (Zeoula et al., 2002). Samples were milled through a 2 mm sieve, packed (5 mg DM/cm²) in a 4 x 5 cm Ankom (filter bags F57 - ANKOM Technology, Macedon, NY, USA) that had been previously weighed, and then incubated for 240 h in the rumen of a Holstein bull (Casali et al., 2008) that was fed a mixed diet of equal parts forage (sorghum silage) and concentrate (the same concentrate that was used in the treatments). After incubation, bags were removed, washed with water until clean, and dried in a forced-air oven at 55 °C for 72 h, after which they were removed and oven-dried again at 105 ºC. The iDM was estimated using the difference in sample weight before and after ruminal incubation. Fecal excretion was calculated with the following equations:

FE = iDMI / iDMCF

Where:

FE = fecal excretion (Kg/d).

iDMI = iDM intake (Kg/d).

iDMCF = iDM concentration in feces (Kg/d).

Apparent digestibility coefficients (ADC) for DM and nutrients were estimated according to the following formula:

DC = [(Intake – Excreted) / Intake] x 100

The DM content of the ingredients (silage and concentrate), orts, and feces was determined after drying the mat at 105 °C for 16 h according to AOAC (1998; method 930.15). Organic matter (OM) content was calculated as the difference between DM and ash, with the ash content determined by combustion at 550 °C for 5 h according to AOAC (1998; method 930.15). Nitrogen (N) content was determined by the Kjeldahl method (AOAC, 1998; method 976.05). Neutral detergent fiber (NDF) content was determined using the methods described by Van Soest et al. (1991) and acid detergent fiber (ADF; AOAC, 1998; method 973.18). Total carbohydrates (TC) were estimated using the following equation (Sniffen et al., 1992): TC = 100 – (% CP + % EE + % Ash). Non-fibrous carbohydrates (NFC) were determined as the difference between TC and NDF. Total digestible nutrient (TDN) content of diets was obtained with the methodology described by Kearl (1982).

Blood was collected twice: at the beginning (d0) and the last day of the experimental period (49 days). Blood samples were collected in Vacutainers^® (BD, Franklin Lakes, NJ, USA) to measure blood cells. Bulls were fasted for 14 h before blood collection. Blood samples were obtained from the jugular vein. A total of 5 mL of blood was collected and mixed with anticoagulant (EDTA: diaminotetracticetilen acid and disodium salt). Hemogram (erythrocytes, hemoglobin, hematocrit, MCV - mean corpuscular volume, MHC - mean corpuscular hemoglobin, MCHC - mean corpuscular hemoglobin concentration) and leukogram (eosinophils, segmented neutrophils, lymphocytes, and monocytes) measurements were performed according to Jain and Jain (1993). Samples were frozen until the analyses, during which they were centrifuged at 1,500 rpm for 15 minutes to collect the plasma.

All variables were tested for normality. Variables showing a normal distribution were analysed using the PROC GLM from SAS (Version 9.1.2.; SAS Institute Inc, Cary, NC, USA, 2004).

Data were compared using analysis of variance and the differences were tested by the Tukey test (5% probability). The following model was used for animal performance, feed efficiency, and total tract apparent digestibility:

Y_ij = μ + D_i + e_ij

Where:

μ = population average.

D_i = treatment (diet) effect.

e_ij = residual error.

For blood cell analyses, the effects of treatment and period (initial or final) were assessed with the following model:

Y_ij = μ + D_i + P_j + D_i^*P_j+ e_ij

Where:

Y_ij = dependent variable.

D_i = treatment (diet) effect.

P_j = collection period.

D_i ^*P_j = interaction between treatment and period.

e_ij = error.

When the effect was significant, differences between mean values were obtained by Tukey (5% probability).

Results

Propolis or essential oils did not affect (p>0.05) intake of DM (Kg/d or % of BW) and other nutrients (Table 3).

Final body weight (BW) and average daily gain (ADG) were greater (p<0.05) for bulls fed the OILbased diet compared with bulls fed CON and PRObased diets (Table 4). The DM conversion was 1.0 Kg greater (p<0.05) for bulls fed the OIL-based diet than the CON-based diet and 0.80 Kg greater for bulls fed the PRO-based diet. Likewise, crude protein conversion and DM efficiency were greater in the OIL diet (p<0.01 and p<0.04, respectively) compared to the other diets (CON or PRO).

The addition of propolis and essential oils did not affect (p>0.05) the apparent digestibility of DM, organic matter, crude protein, ether extract, neutral detergent fiber, total carbohydrates, non-fibrous carbohydrates, and total digestible nutrients (Table 5).

No interaction was observed (p>0.05) between diets vs. period for red and white blood cells. Thus, results are presented and discussed as principal effects.

Addition of propolis or essential oils did not affect (p>0.05) red blood cell means (erythrocytes, hemoglobin, hematocrit, mean corpuscular volume, mean corpuscular hemoglobin, mean corpuscular hemoglobin concentrations), platelets, white blood cell means (leukocytes, eosinophils, segmented neutrophils, lymphocytes, and monocytes), and plasma protein (Table 6) at initial and final collection.

Red blood cell concentrations in all treatments were higher (p<0.05) when comparing initial values and final ones, except for MCHC cells, which were similar (Table 6). However, white blood cell concentrations were lower at the 49^th day of the experiment, except for lymphocyte cell concentrations, which were similar (Table 6). Likewise, plasma protein concentration decreased at the 49^th day of the experiment (Table 6).

Discussion

As observed by Stelzer et al. (2009), the addition of propolis in the diet of dairy cows had no effect on feed intake. The feed intake observed in this study is similar to the values reported by Zawadzki et al. (2011) using growing and finishing cattle completed in feedlots on a diet with a forage-to-concentrate ratio of 48:52%. Likewise, Cruz et al. (2014) did not observe an effect of the addition of essential oils on feed intake of bulls finished in feedlots under similar conditions as in this experiment. DM feed intake for this animal category is between 2.2 and 2.5% BW (Maggioni et al., 2009; Zawadzki et al., 2011; Cruz et al., 2014).

Mean crude protein intake for bulls on the three diets was 1.02 Kg/animal/d. Bulls with body weights between 320 and 360 Kg, depending on their genotype, feed, and environmental conditions, have a crude protein requirement of around 1.0 Kg/animal/d (NRC, 2000). The low intake of NDF and ADF was due to the low NDF and ADF content in glycerine. The mean TDN intake was 6.52 Kg/animal/d, which is the requirement of this category (NRC, 2000).

The mean final weight of bulls was 387 ± 10.7 Kg, and would be the ideal weight to initiate the final stage of finishing. Bulls that are on feedlots during the finishing phase reach body weights between 380 and 400 Kg (Dian et al., 2009; Valero et al., 2011; Zawadzki et al., 2011).

Propolis has been used as a ruminal fermentation modulator (Prado et al., 2010). Zawadzki et al. (2011) observed greater slaughter weights and average daily gains for Nellore bulls fed a diet containing alcoholic propolis extract. They attributed the improved performance observed to the antimicrobial properties of propolis. Furthermore, dietary inclusion of flavonoids can improve animal production, according to Benchaar et al. (2008).

Feed efficiency was better for bulls fed the OILbased diet. Zawadzki et al. (2011) observed better DM efficiency for Nellore bulls fed a propolis extractbased diet using 52% roughage and 48% concentrate. According to the authors, the better DM efficiency may be due to the bioactive compounds in propolis, particularly the antibacterial action associated with presence of flavonoids in propolis extract. However, Albertí et al. (2005) and Devant et al. (2007) found no positive effect on feed efficiency of feedlot cattle by the addition of plant extracts.

Hematological evaluation in cattle is used to assess disease in an animal, to evaluate groups of animals within a herd, to detect hidden diseases, and to guide clinical decisions. The red blood cell series are a reflection of the health and nutrition of animals (Jones and Allison, 2007). The values of the variables observed in this study for red blood cells are in accordance with the reference values described by Biondo et al. (1998). Furthermore, according to the values reported by Biondo et al. (1998) and Jones and Allison (2007), MCV, MCH, and MCHC values in our study are within the normal ranges for cattle.

Measuring of white blood cells in this study was aimed to monitor the health of bulls and observe the behaviour of these cells upon supplementation with propolis and essential oils, due to its recent introduction into ruminant nutrition. The results found in all groups are in accordance with the reference values for cattle during this phase of growth (Jones and Allison, 2007).

Plasma proteins increase or decrease in the plasma as a result of injury or inflammation. Plasma proteins in blood are investigated as a mean of detecting and monitoring inflammatory processes in ruminants (Jones and Allison, 2007). In summary, plasma proteins can provide valuable information to the clinician. Evaluation of plasma proteins is an essential adjunct to detect significant abnormalities in cattle (González et al., 2000). We did not observe any inflammatory processes in the bulls during the experimental period. The results of this experiment are probably due to improved nutrition throughout the experimental period. At the beginning of the experimental (feedlot) period, all animals were treated for endo- and ecto-parasites that are common in the region. Moreover, these animals had no further contact with other animals during the experimental period and were kept on concrete floor stalls that were washed three times a week. The correct management and nutrition during the feedlot period could explain the low levels of white blood cells and plasma proteins in our experiment.

In conclusion, the addition of propolis to the diet of bulls finished in feedlots did not change the average daily weight gain, feed efficiency or apparent digestibility. Therefore, the addition of propolis to the diet of cattle in feedlots is not justified. However, the addition of essential oils to the diet of bulls improved both the average daily weight gain and feed efficiency. Thus, essential oils can be added to the diets of cattle to improve performance and feed efficiency, while acting as a replacement for other products such as antibiotics and ionophores.

Acknowledgements

The current project was supported by Araucaria Foundation, a fund of the Paraná State and the Brazilian Council for Research and Technological Development (CNPq). The authors would like to thank Processing Inc. (Biopar Bioenergia do Paraná, Rolândia, Paraná, Brazil) for providing the glycerine, and Oligo Basics Agroindustrial Ltda. (Cascavel, Paraná, Brazil) for providing financial resources and the castor oil and cashew nut shell liquids used in this research.

Conflicts of interest

Notes

¤To cite this article: Valero MV, Farias MS, Zawadzki F, Prado RM, Fugita CA, Rivaroli DC, Ornaghi MG, Prado IN. Feeding propolis or essential oils (cashew and castor) to bulls: performance, digestibility, and blood cell counts. Rev Colomb Cienc Pecu 2016; 29:33-42.

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