Soybean hull and / or white oat grain for steers finished in feedlot

The aim of this study is to evaluate the performance of feedlot finished steers receiving grain oat and/or soybean hull in their diet. Thirty six Nellore crossbred with Charolais steers, that received diet with concentrate ratio of 50:50 in all diets independently of the treatment, with sorghum silage as forage and concentrate according to the proposed treatment: soybean hull, oat grain and a mixed concentrate with these ingredients (50% of each as energy concentrate), were used. The experimental design was randomized blocks, the data was subjected to analysis of variance and F test using PROC GLM and means were compared by Student's “t”, α = 0.05 probability test. Significant difference was not observed between the treatments for daily gain in live weight of the animals tested. The dry matter intake was not altered by neutral detergent fiber content in this study. Both soybean hulls as the oat grain, had similar performance in feedlot finished steers.


INTRODUCTION
The rearing of cattle for meat production in Brazil occurs predominantly on native and cultivated pastures (ANUALPEC, 2016), with slaughtering being carried out at specific times during the year, causing fluctuations in prices for producers and consumers due to differences in market offers.Thus, there is harvest season and offseason of beef.The feedlot is an alternative, where animals can be finished at specific periods during the year, allowing the producer to obtain differentiated gains in the commercialization of the animals for the slaughterhouses.It should be noted that Brazil can have production stability to meet the external market where, today, it has a privileged place among the three countries that export the highest beef in the world (ANUALPEC, 2016).
When confinement is used in the finishing of cattle, attention should be paid on the formulation and choice of ingredients used in the diets so that there is no financial loss to the producer, due to the production cost or the low performance of the animals.According to Pacheco et al. (2006), feeding is responsible for approximately 73.9% of the total feedlot cost, excluding the value of the animals, with the concentrated fraction of the diet being the most costly.
The increase of soybean production in Brazil (114.9 million tons, 2016/17 crop, IBGE, 2017), mainly for export, and in the second plan, the production of vegetable oil to replace animal fat for human consumption as well as the production of biofuels in Brazil, has led to obtaining by-products available from market for use in confinement.Among these by-products, are the soybean meal and the soybean hulls, which are removed for the extraction of vegetable oil in the Brazilian industry.For each ton of processed soy, about 20 kg is processed into soybean hull (Zambom et al., 2001).
In Rio Grande do Sul, besides this national tendency to increase the areas intended for soybean cultivation, there is an increase in the production of winter grains that are used in the rotation of crops mainly by the increase of the layer of straw on the ground.White oats (Avena sativa L.) are an example of the crops preferred by producers.In the 2016 cropping season, 227 thousand hectares were cultivated (IBGE, 2017) due to lower production costs in winter crops.
In relation to the formulation of diets, the producer or technician must provide the maximum consumption of the animals, which is closely related to the performance of the animals, and reducing these factors interfere with the consumption.Among these factors, the neutral detergent fiber content (NDF) of the feed or diet should be less than 55% (Van Soest, 1994).According to Kozloski (2011), besides the regulation of consumption, the animal can still have its performance altered by feed constituents, which reduce the degradation of feed by ruminal bacteria.In this case, the lignin that constitutes a physical barrier, diminishing and/or hindering the degradation of the feed by the ruminal bacteria can be mentioned.
Results of animal performance were verified in the literature where the soybean hulls were replaced by other ingredients such as grain of sorghum (Restle et al., 2004) and maize (Mendes et al., 2006).Restle et al. (2004) working with diets with 40% concentrate, replacing grain sorghum with soybean hulls, concluded that soybean hulls promoted better weight gain in animals, with a treatment of 0% substitution 1,040 kg/day and 100% to 1.208 kg/day.Earlier, Faturi et al. (2003) providing 38% of black oats in the diet, obtained feed conversion of 9.2 kg of dry matter per kg of live weight gain and digestible energy conversion of 25 Mcal/kg of body weight gain.
Therefore, this study was carried out with the objective of evaluating the performance of beef cattle using soybean hulls and/or white oat grain to clarify the potential of these ingredients in the finishing of steers in feedlot.

MATERIALS AND METHODS
The experiment was carried out at the Cattle Breeding Laboratory of the Animal Science Department of the Federal University of Santa Maria, located in the State of Rio Grande do Sul, Brazil, at an average altitude of 95 m, at 29° 43' south latitude and 53° 42' west longitude.Thirty six steers, from a continuous alternating crossbreeding of two races (Charolais-Nellore) of the experimental herd at the laboratory, with age and average initial weights of 20 months and 226 kg of body weight (BW), respectively, were used.
The finishing of the animals was done in semi-covered confinement (50%) with boxes of 20 m² of area paved, provided with feeders for the supply of feed and drinkers with water at will, regulated with float faucet.Treatments were randomly distributed, with two steers in each box.Before the experimental period, the animals were adapted to the facilities and the diets for 28 days.In this period, the control of endoparasites and ectoparasites was performed with subcutaneous application of ivermectin based product (concentration of 1%), in a dosage recommended by the manufacturer.The steers were divided into three treatments denominated according to the diet to be tested, maintaining a roughage concentrate ratio of 50:50.The sorghum silage (Sorghum bicolor L. Moench) was used for all the treatments (forage) and the concentrate fraction contained soybean hull and/or white oat grain, soybean meal, urea, calcitic limestone and common salt.The treatments evaluated were: Soybean hull (concentrate containing as energy base, soybean hull); white oat grain (concentrate containing as energetic base, white oats grain); and mixture (concentrate containing as energy base, in equal parts, soybean hulls and white oats grain).
The diet was calculated according to NRC ( 2001), aiming at daily gain of 1.20 kg/animal, estimating a dry matter intake of 2.55 kg/100 kg of body weight and establishing isonitrogenated diet.The bromatological composition of the ingredients used to prepare the experimental diets is shown in Table 1.
During the experimental period, the animals were fed twice a day, in the morning at 8 h and in the afternoon at 14 h, and daily, before the first feeding, the leftovers from the previous day were collected and recorded in a spreadsheet, to adjust the consumption of the animals.The forage was supplied in the feeder at the same time with the concentrate in a mixed diet.Voluntary consumption of the diet was recorded daily, the amount of feed offered and the leftovers from the previous day were weighed.The feed supply was pre-established between 50 and 100 g/kg higher than voluntary consumption (Faturi et al., 2006) and regulated according to the consumption of the animals the previous day.
The daily gain of body weight (ADG) of the animals was obtained by the weight difference between weightings, divided by the number of days of the interval (finalinitial), the weightings preceded by fasting of solids and liquids for 14 h.Body condition score (BCS) was determined by scores of 1 to 5 points, attributed by visual observation, where: 1 = very thin; 2 = lean; 3 = medium; 4 = fat; and 5 = very fat (Machado et al., 2008).The BCS was assigned by the same evaluators (three) throughout the study, and the final weight was averaged between the three observations for each animal.The gain of BCS was verified by the difference between the initial and final body state of the experiment.The animals were sent to slaughter when they presented finishing standards according to the regional market (BCS between 3.30 and 3.70 points), being sent in two lots with equal numbers of animals in each treatment.The termination time was 129 days for the first group and 136 days for the second group.
The diet ingredients and the leftover feed samples were taken three times a week, and well homogenized for better sampling.These samples were pre-dried in a forced air drying oven at a temperature of 55°C for 72 h and afterwards milled in a Willey type mill with a sieve of 1 mm and packed in plastic bags free of air for further chemical analysis.The dry matter content was determined by oven drying at 105°C until constant weight (Table 2) and ashes by calcining in muffle at 550°C until constant weight.The organic matter content was calculated by reducing the dry matter value by  , 1995), modified by using a 4% w/v boric acid solution as the free ammonium receptor during distillation, a 0.2% w/v solution of bromocresol green and 0.1% w/v methyl red as indicator, and a standard solution of sulfuric acid for titration.The ethereal extract content was determined after treating the samples with ether, under reflux, at 180°C for 2 h.The levels of neutral detergent fiber, acid detergent fiber and acid detergent lignin were determined according to Van Soest et al. (1991); and the levels of soluble nitrogen, nitrogen insoluble in neutral detergent and acid detergent insoluble nitrogen according to Licitra et al. (1996).The total digestible nutrient content was analyzed according to Weiss et al. (1992).The digestible energy was calculated according to NRC (2001), in which 1 kg of total digestible nutrients = 4.4 Mcal of digestible energy.In vitro degradability of the organic matter of soybean hulls and white oats grain was carried out in the laboratory of the National Institute of Agricultural Technology -Animal Experimental Station -Concepción del Uruguay -Entre Rios (Argentina).

Experimental design and statistical analysis
The experimental design was a randomized block design with three treatments and six replicates, the box being the experimental unit.The animals were blocked by genetic predominance and balanced by fasting initial body weight (solid and liquid) of 14 h between treatments.The data were tested for homogeneity of variance with Levene test and normality using the Shapiro-Wilk test with α = 0.05.
The following transformations were used to achieve data normality: values exponentiated for final weight, initial body condition and mean body weight score, squared values for feed conversion (kg dry weight/kg live weight), log for conversion feed (% body weight) and total dry matter intake from the termination.After that, data were also submitted to analysis of variance and F test using PROC GLM and means comparison using Student's t-test considering α = 0.05 probability.The mathematical model for all variables was as follows: Where, Yij = response variable value in i th block and j th treatment; μ = general mean of all observations; βi = effect of the i th block corresponding to the racial predominance of the animal with i = 2; Tj = the effect of the j th treatment with j = 3; (β*T)ij = effect of the interaction between the i th block and the j th treatment; εij = residual random error.Statistical Analysis System SAS 9.2 (Statistical Analysis System, 2009) was used for analysis.

RESULTS AND DISCUSSION
In the study, interaction between treatment and genetic predominance was not observed (Table 3) and results are discussed in relation to treatments.Animals at the beginning of the experimental period presented no significant difference for body weight (BW) and initial body condition score (IBCS) between treatments (Table 3).Final BW and BCS also did not present statistical difference between treatments, since the animals were slaughtered according to finishing of the carcass.In this way, it can also be observed that the gain of BCS of the animals in the different treatments was similar.
Daily gain of body weight (ADG) for the animals did not differ between treatments, presenting range of 109 g or 11.6% between the ends of values of ADG between the treatment mixture and treatment of white oats grain.Soybean hulls can be used to substitute up to 50% of the corn grain in the concentrated fraction of the diet, according to Mendes et al. (2005a) because it does not influence animal performance and carcass characteristics in confined steers, making the decision on the choice of ingredients to be based on economic criteria.Conversion of steers did not differ in the present study, ranging from 7.5 TO 8.2 kg DM/kg BW.
The soybean hull fraction presents neutral detergent fiber (NDF) values (Table 1) which may decrease the feed consumption of the animals.According to Van Soest (1994), the dry matter intake (DMI) is directly related to the NDF content of the food and the diets, since the fermentation and the passage of this fraction through the reticulum-rumen are slower than those of other dietary constituents, presenting great effect on filling and the remaining feed.
When the NDF content present in the diets consumed by the animals was observed (Table 2), it was verified that only the treatment of the soybean hulls showed greater presence in the diet.This occurred because the ingredient, white oat grain had lower NDF value in relation to the soybean hull (Table 1).The DMI was not altered by the NDF content in this study (Table 3), showing that the use of soybean hull did not influence feed consumption by the physical regulation of the digestive tract which is caused by the NDF content in the diet.
According to Faturi et al. (2006), other factors can influence feed consumption of the animals, that is, digestibility, fermentation products, microbial synthesis efficiency, ability to modify pH and degradation rate of energy and protein.Restle et al. (2004) also considered that it is necessary to evaluate factors such as digestibility and degradation and passage rates of NDF present in the animals' diet, since in their study, they did not observe the influence of NDF on consumption.
The white oats grain used had higher lignin content as compared to soybean hulls (Table 1), but when analyzing the diet consumed by the animals, this lignin content did not show much variation among the treatments (Table 2).Lignin is quite resistant to both chemical and biological degradation, (Hatfield and Fukushima, 2005), preventing nutrients from reaching the ruminal microbiota.It belongs to the diverse class of phenolic compounds, a noncarbohydrate of high molecular weight (Li et al., 2008).
The white oat grain did not influence the feed consumption of the animals, and in this work, it was supplied without any processing to reduce the particles in the diet.As there was no difference in the DMI between treatments (Table 3), the result of the fibrous fraction consumed was a result of the concentration in which each fraction was offered in the diet, in relation to leftover feed.All treatments differed (Table 3) for NDF intake (NDFI), where the largest fraction of NDF consumed, was from the soybean hull treatment (1.60% BW), followed by the treatment mixture (1.42% BW) and finally the treatment of white oats grain (1.16% BW).
In the present study, it was observed that the treatment of white oat grain presented NDF consumption of 1.16% of the BW consuming diet with 45.8% NDF.However, it was observed that when the soybean hulls were used in the diet, the consumption of NDF became 1,597% of the BW, a high value, which corresponds to 62.01% of the diet consumed.The higher in vitro organic matter degradability of soybean hulls (91.5%) as compared to white oats grain (76.4%) may have provided greater ingestive capacity of the diet offered during the first 72 h, even white oat grain presented higher digestibility in the first 24 h in the laboratory (67.9 vs. 53.5%).According to Müller and Prado (2004), the NDF fraction is rich in pectin, a highly degradable carbohydrate.However, when compared with starch, it does not produce lactic acid, promoting a stable fermentation pattern, similar to Table 3. Mean weight and body condition scores (BCS), initial and final, daily body weight gain (ADG), total gain in body condition score (TBCS), feed conversion (FC), dry matter intake (DMI), crude protein intake (CPI), neutral detergent fiber intake (NDFI), acid detergent fiber intake (ADFI), ether extract intake (EEI) and digestible energy intake (DEI) of steers fed different types of concentrated feedlot.forages and decreases the incidence of ruminal and metabolic disorders.Pectin from soybean hulls corresponds to 62.4% of non-fibrous carbohydrates, equivalent to 8.8% of the DM (NRC, 2001).

Variable
In the study of Faturi et al. (2006), the relationship between diets with soluble fiber and starch as carbohydrate sources in cattle production, showed NDF consumption of 1.27% of BW which could be the limiting factor of ruminal distension in animals fed 48% NDF.The same authors concluded that in diets with high content of NDF, soluble fiber promoted a better performance of steers than the starch of low degradability.The difference may be related to the higher digestibility of DM and NDF of diets with higher soluble fiber content than those with higher starch content.Thus, it can be deduced that the best digestibility of diets with high soluble fiber content is related to the ability to maintain higher ruminal pH in comparison with diets containing high starch content (Bomfim, 2003).
According to Mendes et al. (2005b), the higher amount of fiber in the diet containing soybean hull as compared to maize did not affect the food consumption of the animals, as in this study, as compared to the white oats grain, possibly due to the higher digestibility of its fiber in acid detergent (ADF) or the rate of passage of this ingredient.The digestibility of fractions ADF and NDF were higher, respectively 33.8 and 11.2%, for the diet with soybean hulls when compared with the corn diet (Mendes et al., 2005b).
The ruminal apparent digestibility of the crude protein (CP) is the closest to zero, meaning that there is a synchrony between energy and protein available for ruminal microbial growth (Mendes et al., 2005b).The fibrous fraction and ethereal extract (EE) content were also determined by the concentration in the diet of the animals, since there was no difference in the DMI among the treatments studied.
The digestible energy consumed (Table 3), expressed in absolute values per day, was similar among the treatments, but when expressed in values related to BW, it was observed that the consumption of the soybean hull treatment was lower than the treatments (mixture and white oats grain), which showed no difference between them.This result may be related to the total digestible nutrient (TDN) content of the diets that were different from each other (Table 2).Different values of TDN should provide different performances (Ezequiel et al., 2006a), but when using coproducts it may not occur, leading to serious questions about the nutritional components analyzed to obtain the TDN.Probably, other components of fibrous origin, such as soluble fiber (Faturi et al., 2006;Ezequiel and Galati, 2005), are part of these ingredients that may favor microbial growth in the ruminal environment.Thus, the soluble fraction of the fiber that has nutritional value would not be part of the TDN, explaining its underestimation.Still, according to Ezequiel et al. (2006b), this fact seems to be aggravated by the conventional methodologies of analysis, which are not able to determine these differentiated fractions and are present in the co-products of agroindustry.
There was no difference in the protein efficiency (Table 4) of the animals in relation to the treatments studied.According to Sujak et al. (2006), oat protein is a good source of sulfur amino acids and, therefore, it should preferably be used in combination with legumes that are low in methionine and cysteine.In the present study, there was no difference between treatments in relation to feed consumption of animals in absolute values for both DM and CP.According to Mendes et al. (2005b), differences in dietary protein efficiency between treatments may be due to lower intake of DM and, consequently, lower intake of CP.The treatment of white oat grain showed higher feed efficiency of ADF (Table 4) as compared to the treatment mixture, which in turn, was higher than the treatment of the soybean hulls.When the feed efficiency of NDF was compared, the treatment of white oats grain and the mixture were more efficient than the soybean hulls treatment.In the study of lipid efficiency, the treatment of soybean hulls was superior to the other treatments studied, which also differed, since it was able to provide the same ADG as the other treatments, with a lower content of EE in the diet.
These results demonstrate that the NDF of the soybean hulls treatment was important for the performance of the animals, providing similar ADG to the other treatments that used as body growth, the lipid fraction of the diet, as in the case of treatment with white oats grain.
Energy efficiency was different among the different energy sources evaluated.The treatment mixture was superior to the soybean hulls treatment, which in turn, was superior to that of the white oats grain.When expressing the energetic conversion in Mcal/kg of ADG, the following values: 22.73; 22.22 and 25.00, respectively were obtained for treatments of soybean hulls, mixture and white oats grain.Values similar to that of the treatment of white oat grain were observed by Faturi et al. (2003) when working with two-year-old steers finished in confinement, but fed with black oat grain ground in the concentrate, whose mean value is 25.0 Mcal/kg of ADG.In another study, Restle et al. (2009) found similar values for digestible energy conversion (25.6 Mcal/kg) when evaluating the processing of black oat grain to feed discard cows in feedlot.
With evaluation of the feed efficiency without discrimination by nutritional fractions, calculated DMI, showed ADG values of 0.126; 0.133 and 0.124 kg/kg DMI for the soybean hull, mixture and white oat grain treatments, respectively, demonstrating that there is a small variation of 7.26% between the excesses of the treatments studied, which are the white oats grain and mixture.Mean value of 0.140 kg ADG/kg DMI of feed efficiency was obtained by Marcondes et al. (2011) when evaluating the Nellore cattle feed efficiency (0.133 kg ADG/kg DMI), Nelore-Angus crossbred (0.128 kg ADG/kg DMI) and Nellore-Angus crossbred (0.128 kg ADG/kg DMI) that received 1 or 2% from concentrate in the diet.

Conclusion
The supply of soybean hull or white oat grain as the main energy source of the concentrated fraction in diet shows similar performance for finished steers in feedlot.

Table 1 .
Chemical composition of the ingredients used for preparation of the diets.

Table 2 .
Ingredients for green matter and chemical composition of dry matter of the offered diets.

Table 4 .
Protein efficiency, neutral detergent fiber (NDF), acid (ADF), lipid (EE) and energy of steers fed different types of concentrates in a feedlot.