Performance and immune response of steers Nellore finished in feedlot and fed diets containing dry leaves of Baccharis dracunculifolia

This study was carried out to investigate the effects of addition Baccharis dracunculifolia leaves in nature on animal performance, feed intake, ingestive behavior, and blood parameters of Nellore steers finished in feedlot on high-grain diets. A total of 40 Nellore steers, with an average body weight of 412.9 ± 22.0 kg were distributed in individual pens, equipped with automatic drinkers and masonry feeders. The steers were randomly assigned to one of four studied diets, therefore the CONT – basal diet; BAC05 – basal diet and inclusion of B. dracunculifolia leaves in natura (5 g/animal/day); BAC10 – basal diet and inclusion of B. dracunculifolia leaves in natura (10 g/animal/day); and BAC15 – basal diet and inclusion of B. dracunculifolia leaves in natura (15 g/animal/day). The use of plants in nature did not affect final body weight, average daily gain, dry matter intake, or feed efficiency. Neither on ingestive behavior activities and plasma concentrations of urea, creatine, aspartate aminotransferase, gamma-glutamyl transferase, and creatine kinase no effects were detected between diets. The inclusion of plants in nature in steer’s diet did not negatively impact performance and health. However, further field studies with beef cattle are needed for greater clarification of its effects and dosages.


Introduction
The efficiency in beef cattle production is considered a great challenge and has been a target of innumerable research and discussions over the years, indicating the need to maximize production through the development of the entire meat production chain. The finishing phase in a feedlot of the animals, which was been studied in this work is one of the phases more important on the production cycle. This is an onerous phase due to the high costs of a quality feed, thus allowing the animals to express their full genetic potential. Thus, the use of new alternatives to increase the productivity of the cattle herd has been studied more frequently, being the class of growth promoters in the highlighted (Fugita et al., 2018;Monteschio et al., 2017;Ornaghi et al., 2017;Souza et al., 2019).
In the last decades, antibiotics were commonly administered in the diet of animals with the function of modulating bacterial flora, but their use is undergoing some restrictions in European Union (OJEU, 2003) and the USA (FDA, 2015). Therefore, alternative products that promote a satisfactory animals' performance without compromising the quality of the final product (meat) offered to beef consumers are being investigated (Cruz et al., 2014;Monteschio et al., 2017;Rivaroli et al., 2016).
In this situation many studies are being carried out in this area, searching for a natural substitute that meets such requirements. The use of plant extracts is an alternative to replace antibiotics (Benchaar et al., 2008;Cruz et al., 2014;Valero et al., 2016), besides acting as antimicrobials and antioxidants, benefiting the immune and digestive system of animals (Jayasena & Jo, 2013;Ornaghi et al., 2017).
This study was carried out to evaluate the effects of the addition/inclusion of plant leaves of Baccharis dracunculifolia in nature on animal performance, feed intake, ingestive behavior activities, and blood parameters of steers finished in the feedlot with high-grain diets. Development, v. 9, n. 10, e339107776, 2020 (CC BY 4.0) | ISSN 2525-3409 | DOI: http://dx.doi.org/10.33448/rsd-v9i10.7776 5

Ethics committee
This experiment was approved by the committee for ethics in the use of animals (CEUA) of the Universidade Estadual de Maringá, following protocol 3624120116.

Animals and experimental diet
Forty Nellore purebred steers with a mean initial body weight (BW) of 412.9 ± 22.0 kg were used in this study. Steers were distributed randomly in individual pens, with dimensions of 10 m 2 for each animal, partially covered and equipped with automatic drinkers and masonry feeders. The period of adaptation to the feedlot and concentrate diet was 14 days; afterwards, the experimental period was extended to 56 days until animals reached a mean final body weight of 499.9 ± 25.6 kg. During the experimental period, Nellore steers were weighed monthly to record weight gain and productivity variables. We used the quantitative method (Pereira et al., 2018), carried out by means of field research to assess the performance, feed intake, ingestive behavior, and blood parameters of Nellore steers finished in feedlot on highgrain diets Steers were randomly assigned to one of four studied diets with ten steers per diet group.
The diets tested were CONTbasal diet; BAC05basal diet and inclusion of B. dracunculifolia leaves in natura (5 g/animal/day); BAC10basal diet and inclusion of B. dracunculifolia leaves in natura (10 g/animal/day); and BAC15basal diet and inclusion of B. dracunculifolia leaves in natura (15 g/animal/day). The plant included in the diet was made every 15 days, to calculate and adjust the dose by period depending on the intake of dry matter (DM)/d per animal. Preparation of diets was made with a pre-mix of plant in nature in the soybean meal and ground corn then led to the feed mixer together with other ingredients. The Leaves of B. dracunculifolia in nature had a powder texture and were obtained of a single property through the manual collection of the leaves of the plant, which were processed in a knife mill to be offered to the animals.
The basal diets, consisting of pre-dried Tifton 85 hay, corn grain, and the dry leaves of B. dracunculifolia in nature was mixed with soybean meal, ground corn, yeast, mineral salt, and top-dressed daily into the morning feeding of respective treatments pens (1.60 kg of mixture/steers daily). Soybean meal was also top-dressed into the morning feeding of CONT Research, Society and Development, v. 9, n. 10, e339107776, 2020 (CC BY 4.0) | ISSN 2525-3409 | DOI: http://dx.doi.org/10.33448/rsd-v9i10.7776 6 pens (1.60 kg/steers daily), without the addition of the experimental ingredients. All diets were isonitrogenous, isoenergetic, and formulated to meet the requirements for a gain of 1.7 kg/d (NRC, 2000) with adequate concentrations of nutrients for the growth and finishing of animals (Table 1).

Chemical analyses
The chemical compositions of ingredients and experimental diets were presented as g/kg of DM (Table 2).

Animal performance
Diets were offered at 08:00 and 16:00 h every day. Feed intake was estimated as the difference between the feed supplied and refusals in the trough. To determine growth performance, animals were weighed at the beginning of the experiment and then every month (after fasting for 16 h), throughout the experiment. The average daily gain was calculated as the total BW gain divided by the length of the experimental period (56 days). Feed efficiency was calculated as the ratio between average daily gain and DM intake.
When the Nellore steers reached a mean final body weight of 499.9 ± 25.6 kg, they were slaughtered in a commercial slaughterhouse 153 km from the Iguatemi Experimental Farm.
Animal transport was carried out in the late afternoon to minimize stress. Upon arrival at the slaughterhouse, animals were kept in resting pens and were subsequently stunned using a Research, Society and Development, v. 9, n. 10, e339107776, 2020 (CC BY 4.

Ingestive behavior activities
Data relative to the ingestive behavior of steers were obtained between the 7 th and 8 th weeks of a feedlot. The record of the quantitative data on the basic behavioral patterns was according to Silva et al. (2005), through visual observation of the animals every 5 min during 1 minute performed by a trained team during 12 uninterrupted hours. A spreadsheet was used to organize the records collected chronologically regarding the duration of feeding and drinking by the number of action observation times. For ruminating and idle periods, the total time spent on each activity was determined by the sum of the repetitions.

Blood analyses
Blood samples were evaluated every 18 days for a total of three individual collections per animal in the vacutioner ® tube and maintained at a temperature of 25 0 C with the mean for facilitating the coagulation, and then were performed the serum separation by centrifugation

Statistical Analyses
The experimental design was completely randomized with four treatments and ten replications. The results were statistically interpreted using regression equations performed in

Results
The inclusion of up to 15 g/animal/day of the leaves of Baccharis dracunculifolia in nature in the steers' diets finished in the feedlot did not affect (P ≥ 0.47) final body weight, average daily gain, dry matter intake, and feed efficiency (Table 3). 1 CONT = basal diet; 2 BAC05 = basal diet and inclusion of B. dracunculifolia leaves in natura (5 g/animal/day); 3 BAC10 = basal diet and inclusion of B. dracunculifolia leaves in natura (10 g/animal/day); and 4 BAC15 = basal diet and inclusion of B. dracunculifolia leaves in natura (15 g/animal/day); 5 SEM -standard error of the mean; 6 kg average daily gain/kg dry matter feed intake. Source: Authors.

Discussion
The finished period, especially feedlot is a term in which beef cattle need a contribution against diseases, metabolic disorders, and ruminal digestion as fermentative modulators (Russell & Strobel, 1989;Souza et al., 2018). The B. dracunculifolia has great importance in Brazilian botany (Bankova et al., 1999;Campos et al., 2016;Silva Filho et al., 2004), because of their antibacterial effect (Silva Filho et al., 2008;Veiga et al., 2017) this same effect is found both in the plant in nature and in the propolis and/or as it can be called "green propolis" that is produced by bees that use the nectar of the plant flowers.
The studies reported by other authors Zawadzki et al., 2011) prove that the use of propolis in beef cattle diets can improve the average daily gain. This improvement is due to the efficiency of the use of nutrients in the rumen, as a decrease in the losses coming from the methane gas (Callaway et al., 2003). However, the results from the current experiment did not report an improvement on average daily gain variables with the addition/inclusion of the leaves of B. dracunculifolia.
Even without the differentiation between the treatments from animals that received or not the supplementation with the plant extracts, the average daily gain can be considered satisfactory for feedlot animals fed a high grain diet on the Nellore breed (Françozo et al., 2013;Maggioni et al., 2010). The final body weight, dry matter intake, and feed efficiency had similar results between treatment animals throughout the experimental period (Table 3). The plant in nature presents high levels of flavonoids and phenol (Kumazawa et al., 2003;Paula et al., 2017), consequently, these concentrations in steers' diet negatively influenced ruminal dynamics, justifying the lack of effect detection for feed efficiency.
Ingestive behavior activities (feeding, drinking, ruminating, and idle; Table 4) were similar among the treatments that received the vegetal extract or not, this resemblance is possibly explained due to the similarity between the feedlot pens, as well as the basal diet offered to the animals. Corroborating with these results other works carried out under similar conditions and with the inclusion of natural additives (essential oils) as those from our research group (Ornaghi et al., 2017) who did not detect either effect for ingestive behavior on young bulls receiving a high concentrated diet.
Results for feeding and ruminating are in according with (Eiras et al., 2014;Missio et al., 2010;Ornaghi et al., 2017) who also evaluated ingestive behavior on beef cattle feedlot supplemented with a high concentrated diet. The low levels for these activities are understood due to the greater energetic support that this type of diet provides; thus, the animals reach their nutritional requirements and cease their consumption. According to Van Soest (1994), a diet with a higher percentage of forage increase the time used for rumination, that is, a high concentrate diet due to the size of its particles may have reduced the rumination capacity of the present study steers. Another factor that may have compromised the rumination rate is the high levels of phenolic substances found in B. dracunculifolia (Park et al., 2002;Tiveron et al., 2016) which adversely affected the use of feed by ruminal bacteria.
The observation of the beef cattle behavior from feedlot presents great importance, to guarantee the maximum production of the animals without taking unnecessary management, avoiding more intense periods used by the animals in the use of feed intake. In addition, the feed offered to animals at shorter intervals of time is aimed at improving the absorption of the nutrient (Ítavo et al., 2011).
Stresses being by transport, dehydration, or nutrient-poor diets influence metabolism, through changes in plasma concentrations of urea, total protein, and creatine kinase (Buckham Research, Society and Development, v. 9, n. 10, e339107776, 2020(CC BY 4.0) | ISSN 2525-3409 | DOI: http://dx.doi.org/10.33448/rsd-v9i10.7776 et al., 2008Earley & O'Riordan, 2006;Tarrant et al., 1992). Corroborating with this affirmation Berschauer et al. (1983) report that with increasing feed intake there is a decrease in blood urea concentrations. In the present study, the results for urea, creatine, and creatine kinase were above what is classified as a reference for cattle (Table 5). Therefore, these results indicate that the steers did not suffer any type of metabolic alteration during the experimental period, but in the period before the experiment.
The plasma blood concentration of steers fed B. dracunculifolia for aspartate aminotransferase and gamma-glutamyl transferase were higher according to the results found by Gandra et al. (2012). The possible explanation for this small difference is the forage: concentrate ratio of the diet, since high concentrate diets can induce liver injury (Mori et al., 2007). Therefore, with the inclusion of the plant extract, no clinical alterations were observed due to infectious, neurological, or metabolic diseases, which could negatively influence the performance and health of the steers.

Conclusion
The inclusion up to 15 g/animal/day of dry leaves of Baccharis dracunculifolia in nature does not affect animal performance, ingestive animal behavior, and blood plasma parameters on finished steers in a feedlot. The results from this study suggest that the use of this plant in the diet of steers does not cause any feed injury.