Assessing the Effect of Fermented Chestnuts on Growth Performance, Carcass Traits, and Meat Quality in Hanwoo Steers During the Late Fattening Period

| The objective of this study was to examine the effects of dietary fermented chestnuts on the growth performance, carcass parameters, and meat quality in the late fattening period of Hanwoo steers for 72 days. Eighteen castrated Hanwoo steers (615.8 ± 1.0 kg, 28 months old) were assigned into two groups (control vs. treatment), with nine Hanwoo steers in three replicates (three heads per replicate) for each group. The Hanwoo steers in the control group were fed a concentrate mix and rice straws, whereas those in the treatment group supplemented the control diet with 5% fermented chestnuts. Growth performance of Hanwoo steers was not different between the two groups (p>0.05), and 5% fermented chestnut supplementation had no effect on carcass trait (p>0.05). For meat quality, the application of fermented chestnuts to the Hanwoo steers diet exerted no significant effect in terms of chemical composition and physicochemical characteristics (p>0.05), except for pH (p<0.05). Considering the fatty acid profiles, the addition of 5% fermented chestnuts resulted in no significant difference (p>0.05) in the individual percentages of fatty acids, the relative percentages of saturated fatty acids (SFA) and unsaturated fatty acids (UFA), and the SFA:UFA ratio. However, fermented chestnut supplementation affected the percentages of margaroleic acid, stearic acid, and arachidonic acid (p<0.05). In conclusion, supplementation of 5% fermented chestnuts did not improve growth performance, carcass traits, and meat quality in Hanwoo steers. No more did the addition of fermented chestnuts in the diets demonstrate any detrimental effect during fattening Hanwoo steers.


INTRODUCTION
D uring the past 70 years, antibiotic growth promoters have been applied in farm animals to improve growth production and meat quality. Over time, farm animals are frequently exposed to not only the overuse of antibiotics but also antibiotic-resistant bacteria, which are important contributors to the increase in antibiotic resistance. Since 2006, countries in the European Union have banned the

Advances in Animal and Veterinary Sciences
September 2019 | Volume 7 | Issue 9 | Page 771 (Goel et al., 2005). Dietary chestnut at 5% for pig increase feed intake and digestibility (Lee et al., 2016). In poultry, supplementation of chestnut tannin at 250/500 mg/kg in the feed increase body weight and feed conversion ( Jamroz et al., 2009). On the ruminants, there are numerous studies on the use of chestnuts tannins in nutrition and production that had benefit on N utilization and decreasing CH 4 emission (Deaville et al., 2010;Liu et al., 2011).
In the past, tannins were considered as anti-nutritional substances that decreased the digestibility of grazing animals, but it is now known that the biological activities of dietary tannins positively affect average daily gain and reduce bloating in steers grazing winter wheat (Min et al., 2006). In terms of meat quality, evidence has shown that tannins are mainly related to color stability and shelf life (Luciano et al., 2009;Luciano et al., 2011). That evidence can support that dietary chestnut tannins have similar effects with antibiotics and its advance research can help to decrease the use of antibiotics for livestock production. However, few studies have investigated the effects of fermented chestnuts on the meat quality of animals. Chestnuts are produced annually in South Korea, but part of the annual chestnut production becomes waste. Thus, other strategies to utilize chestnuts include their application as a dietary supplement for Hanwoo steers through the fermentation process. In our hypothesis, application of chestnut tannins in beef cattle could improve performance and its meat quality considering beneficial effect of tannins. Therefore, the aim of this study was to examine the effect of growth performance and meat quality on Hanwoo steers fed fermented chestnuts during the late fattening period.

MATERIAL AND METHODS
All animal procedures were conducted at Woojung farm (Changwon, South Korea) and approved by the administration office of Gyeongsang National University ( Jinju, South Korea) under the animal care and use guidelines of the Animal Research Unit.

FermenteD CHeStnut
Chestnut samples were obtained from the Hapcheon Agricultural Co-operative Society (Hapcheon, South Korea). The chestnut was dried in a forced-air oven at 60°C for 48 h and ground in a hammer mill to obtain particles with a diameter of 5-10 mm. For the fermentation process, 5 kg of chestnut powder was mixed with 2.4 L of distilled water, 15 g of molasses, and 100 mL of Bacillus subtilis (2 × 10 9 CFU/mL). After sealing, the mixture was incubated at 39°C for 48 h in a shaking incubator for seven days. During incubation, the mixture was gently shaken for 30 min at three-hour intervals.

animaLS anD DietS
A total of 18 castrated Hanwoo steers (average initial body weight of 615.8 ± 1.0 kg, 28 months old) were assigned to two groups (control vs. treatment). Each group consisted of nine Hanwoo steers that were placed in three pens as replications (three steers per pen) for 72 days of feeding period. The Hanwoo steers in the control group were fed a concentrate mix and rice straws, whereas those in the treatment group received the control diet plus 5% as fed of fermented chestnuts. The Hanwoo steers were placed in a pen (5 m × 8 m) installed with a feeder in a slatted floor. Water was offered ad libitum during the experimental period. The diet was fed at 2.5% dry matter (DM) of the body weight of the steers in two equal portions at 09:00 h and 17:00 h daily. The Hanwoo steer received concentrate/ roughage at a ratio of 60:40 on the DM basis. The experimental diets were formulated isonitrogenous and isocaloric to supply nutrient requirement of late fattening period according to the Korean Feeding Standards for Korean Cattle developed by the National Livestock Research Institute (KFS, 2007). The composition of the ingredients in the experimental diets is summarized in Table 1. Analysis of experimental diets (Table 1) was performed according to the methods of the Association of Official Agricultural Chemists (AOAC, 2005). Feed intake was calculated daily by measuring orts before morning feeding. For growth performance, the Hanwoo steers were weighed at the beginning (initial body weight) and the end of feeding period (final body weight) to determine average daily gain and average daily feed intake for the entire feeding period. Feed efficiency was calculated as the ratio between average body weight gain and feed intake on the basis of DM.

CarCaSS traitS
At the end of the feeding period, all Hanwoo steers fasted for 24 h and were moved to a local municipal slaughterhouse (Gosung, South Korea) to evaluate carcass yield and quality. Following a 24-h carcass chill, cold carcass weights were measured, and the left side of the carcass was opened between the 13 th rib and the 1 st lumbar vertebrae to meas-

Advances in Animal and Veterinary Sciences
September 2019 | Volume 7 | Issue 9 | Page 772 ure back fat thickness and the longissimus muscle area. The yield and quality grade in each carcass were determined according to the Korean carcass grading procedure classified by the Korean Livestock Enforcement Regulation (KMAF, 2007). The degree of marbling and scores of meat color and fat color were evaluated according to the Korean Beef Marbling Standard and the Color Standard (KAPE, 2012), respectively. Marbling score ranged from 1 (poor) to 9 (excellent) with higher numbers indicating better quality. The score of meat color ranged from 1 (scarlet) to 7 (dark red) and fat color was graded from 1 (white) to 7 (dark yellow).

anaLYSiS
The moisture, crude protein, and crude fat contents of meat samples were determined following the methods of the AOAC (2005). After 24 h postmortem, approximately 10 g of minced meat was added to 90 mL of distilled water and homogenized for 1 min. The pH of the homogenized sample was determined using a pH meter. For cooking loss, approximately 100 g of meat sample in a polyethylene bag was boiled in a water bath at 70℃ for 30 min and cooled at room temperature for 30 min. Cooking loss was calculated as the difference in meat weight before and after cooking. Water-holding capacity was measured according to the method described by Kristensen and Purslow (2001). First, 0.5 g of muscle sample in each line was placed in a centrifugation tube with filter units. The samples were heated for 20 min at 80℃ and then cooled for 10 min. After centrifuging at 2,000 × g for 10 min at 4℃, the water-holding capacity was calculated as the change in sample weight. Shear force values were measured using a rheometer (CR-300, Sun Scientific Co., Tokyo, Japan). Each core was sheared in parallel to the muscle fibers using Warner-Bratzler attachment to the load cell with 5 kg applied at a cross-head speed of 30 mm/ min. Fatty acids were extracted from the LD muscle using a mixture of chloroform/methanol (2:1, vol/vol) following the method described by Folch et al. (1957). Fatty acid methyl esters were analyzed by gas chromatography (GA-17A, Shimadzu, Tokyo, Japan) equipped with a flame ionization detector and a CP-Sil 88 column (100 m × 0.25 mm × 0.2 µm; Chrompack, Middelburg, Netherlands). Fatty acid peaks (C14:0 to 24:1) were identified by comparison of the retention times in the standard fatty acid methyl ester mixtures (Sigma-Aldrich, Germany). Fatty acid data were presented as a percentage of each individual fatty acid relative to total fatty acids.

StatiStiCaL anaLYSiS
All data are expressed as the mean ± standard error of the mean. All statistical procedures were carried out using the generalized linear model procedure of the SAS statistical package (SAS Institute, 2004). The model was Y ij = µ + T i + e ij , where Y ij = response variable, µ = overall mean, T i = the effect of treatment i, e ij = error term. The significant differences between the means were declared at p < 0.05 using Student's t-test, while the tendency differences were declared at p < 0.1.

RESULTS AND DISCUSSION
The growth performance of Hanwoo steers fed fermented chestnuts during the late fattening period are shown in Table 2. The chestnut tannin reduces the N loss production and CH 4 emission in the ruminants that indicate an improvement on digestive utilization of feed (Deaville et al., 2010;Liu et al., 2011). Moreover, it increases flow rate of amino acid in small intestine that can be absorbed highly by ruminant. By these effects, the chestnut tannin may influence the growth performance of ruminant (Frutos et al., 2004). However, initial body weight, final body weight, average daily gain, average daily feed intake, and feed efficiency were not different between the two groups (p > 0.05) in the present study. Similar results were reported by Krueger et al. (2010), where tannin treatment did not improve growth performance during the 42-day fattening period. In the current study, supplementation of fermented chestnut at 5% had lower beneficial effects on growth performance and meat quality than control. This might be due to the characteristics of the fermented chestnuts, which depend on the origin of tannins and the fermentation process (Frutos et al., 2004). For example, high tannin intake has no positive effect on productivity, voluntary feed intake, and digestibility, whereas nutrient availability is decreased because of the strongly formed complexes between tannins and other macromolecules (Frutos et al., 2004). Ultimately, the 5% fermented chestnuts applied in our study did not show detrimental effects on growth performance.

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September 2019 | Volume 7 | Issue 9 | Page 773 effect on cold carcass weight, backfat thickness, longissimus muscle area, marbling score, and fat color (p > 0.05). The results of this study agree with those of Krueger et al. (2010), as different types of tannins (chestnut tannin and mimosa tannin) exerted no effect on selected carcass traits in steers. However, back fat thickness and longissimus muscle area were lower in Hanwoo steers fed 5% fermented chestnuts.
Although the most important factors in evaluating beef quality are marbling score, meat color, and fat color, the mechanisms of fermented chestnuts with respect to carcass traits are uncertain. Moreover, the type and concentration of tannin could be different among sources, which might not always be a promising improvement in animal performance and carcass quality (Krueger et al., 2010). Fat color 5 3.0 2.8 0.316 0.347 1 5% FCN: 5% fermented chestnut. 2 SEM: Standard error of the mean. 3 Scored: grade 1 (poor) through grade 9 (excellent). 4 Scored: grade 1 (scarlet) through grade 7 (dark red). 5 Scored: grade 1 (white) through grade 7 (dark yellow). Table 4 summarizes the data concerning the chemical composition, physicochemical characteristics, and fatty acid profiles in Hanwoo steers fed fermented chestnuts. With regards to chemical composition, moisture and crude protein content in the loins of Hanwoo steers fed 5% fermented chestnuts were equal to those of control Hanwoo steers loins. There was a numerical lower crude fat content was observed in Hanwoo steers fed 5% fermented chestnuts compared with control. At present, the reasons for the reduction in crude fat by 5% fermented chestnuts are unclear. In addition, the biological activities of plant tannins and animal responses to tannins have been extensively reviewed, mainly focusing on ruminant nutrition and production with respect to proteins (Hunag et al., 2018). In terms of physicochemical characteristics, changes in meat quality parameters, which contribute to cooking loss, water-holding capacity, and shelf life, can markedly influence meat pH (Li et al., 2014). In the current study, the addition of 5% fermented chestnuts to the diet of Hanwoo steers during the late fattening did not affect these factors. To the best of our knowledge, information on meat quality using fermented chestnuts as a source of tannins for ruminants is rather limited. Considering individual fatty acids, our result showed no significant difference in the percentages of myristic acid (C14:0), palmitic acid (C16:0), palmitoleic acid (C16:1), margaric acid (C17:0), oleic acid (C18:1c-9), and linoleic acid (C18:2n-6) between the two groups (p > 0.05). However, fermented chestnut supplementation exerted an effect on the percentages of margaroleic acid (C17:1), stearic acid (C18:0), and arachidonic acid

Advances in Animal and Veterinary Sciences
September 2019 | Volume 7 | Issue 9 | Page 774 (C20:4n-6) (p < 0.05). As the major fatty acid profile, stearic acid largely is produced throughout biohydrogenated oleic acid by ruminal microbes. Moreover, dietary fiber increases stearic acid concentration in duodenal flow (Smith et al., 2009). Addition of fermented chestnut in the present study could increase the total fiber content in the diet, which might increase stearic acid concentration in the loin. Overall, the percentages of individual fatty acids were similar between the two groups. In the present study, the addition of fermented chestnuts into Hanwoo steers diets did not increase or decrease the relative percentages of saturated fatty acids (SFA) and unsaturated fatty acids (UFA), and the SFA:UFA ratio compared with those in the control groups (p > 0.05). This implied that the use of fermented chestnuts led to poor efficiency in improving fatty acids via antioxidant effects. Recently, the potential application of tannins as biological antioxidants has been reported in several studies in cattle and sheep (Dey and De, 2014;Peng et al., 2016). However, the antioxidant mechanism of fermented chestnuts in Hanwoo steers is unknown.

CONCLUSION
The study revealed that the addition of 5% fermented chestnuts to Hanwoo steers diets had no obvious effects on growth performance, carcass traits, and meat quality. In turn, no negative effect of fermented chestnuts was demonstrated. The effects of optimal levels of fermented chestnuts on production and meat quality and their mechanisms in Hanwoo steers fatteners warrant further investigation.