Abstract
The study was conducted to determine the chemical composition and nutritive value of sorghum dried distillers grains with solubles (sDDGS) and its effect as a feed supplement on the performance of geese. Experiment 1 showed that the gross energy, crude protein, ether extract, crude fiber, calcium, phosphorus, and amino acid content values of sDDGS were 17.87 MJ/kg and 15.48, 4.26, 31.46, 0.17, 0.25, and 0.06–3.18% [dry matter basis (DM)], respectively. Experiment 2 used fasting–force feeding to measure the true metabolizable energy of sDDGS (11.38 MJ/kg DM) and true total tract digestibility of amino acids (43.16–80.92% DM) in geese. Experiment 3 examined the effectiveness of sDDGS as a feed supplement for geese. Three hundred and fifteen 35-day-old male Sichuan white geese with an initial average bodyweight of 1,732 g were randomly allocated to five treatments. Geese in each treatment group were fed one of five experimental diets (control diet alone, or supplemented with 4, 8, 12, or 16% sDDGS) until 70 days of age. Inclusion of sDDGS in the diet did not affect daily average weight gain (P>0.05). Birds fed diets containing up to 8% sDDGS had higher average feed intake (P<0.05) than geese fed the control diet, and the feed/gain ratio in geese fed diets containing 16% sDDGS was higher (P<0.05) than in the control and the 4% sDDGS group. The yields of breast meat, leg meat, subcutaneous fat and skin, and abdominal fat were not affected (P>0.05) bydietary sDDGS levels. Generally, sDDGS is a potentially valuable feedstuff for geese, but it should be supplemented with a high-energy or protein-rich ingredient. To improve growth performance and carcass yield, up to 12% sDDGS can be included in diets from 35 to 70 days of age.
Introduction
Sorghum is a premier upland crop cultivated in Africa, Asia, Oceania, and America. Besides its use as a feedstuff, sorghum is used to produce distilled spirits and biofuel. In China, about 2.5–2.8 million tons of sorghum is used per year in distilled spirits production, and this produces about 1.5–1.7 million tons of sorghum dried distillers grains with solubles (sDDGS) as a by-product (Lu et al., 2009). sDDGS is rich in crude fat (8.8–13%), crude protein (32.9–35.9%), and amino acids (0.38–6.92%) (Al-Suwaiegh et al., 2002; Urriola et al., 2009). Recently, sDDGS has been successfully used as an energy and protein source to feed beef and lactating dairy cattle (Al-Suwaiegh et al., 2002; Gill et al., 2008; Van Overbeke et al., 2008; May et al., 2010), pigs (Stein and Shurson, 2009; Urriola et al., 2009), and broilers (Barekatain et al., 2013a, b).
Goose meat is a source of high-quality protein for human consumption, and it is rich in both unsaturated and essential fatty acids, and low in cholesterol (Schmid, 2010). As a result, there is growing interest in increasing goose production throughout the world. In 2013, more than 6.48 billion geese were used for meat production in China (Gong, 2015). Furthermore, because of their ability to digest fiber-rich feed, geese can be supplied with food supplemented with roughage, thus allowing some cost savings over the use of conventional feed grains such as corn and soymeal. Given the nutritive value of sDDGS, it maybe useful as a common feed for geese, although there is little information regarding the potential value of sDDGS in goose production. This study was conducted to determine the chemical composition of sDDGS, its digestibility by geese, and its effect on goose growth performance and carcass characteristics.
Materials and Methods
Animal Ethics
The present research was approved by the Animal Care and Welfare Committee of the Chongqing Academy of Animal Science (CAAS), China. The sDDGS used in the present studywas a by-product of a mixture of 5% rice hull and 95% red sorghum used for distilled spirit production, and it was obtained from Zhisheng Distilled Spirit Company Limited, Chongqing, China. All geese used in this experiment were obtained from the goose-breeding center of CAAS.
Chemical Composition of sDDGS
The samples were analyzed for dry matter (AOAC 4.1.06), gross energy(PARR 6400 calorimeter, Moline, IL, USA), crude protein (AOAC 990.03), ether extract (AOAC 920.39), crude fiber (AOAC 978.10), calcium (AOAC 4.8.03), and total phosphorus (AOAC 3.4.11) (AOAC International, 2000). Methionine and cystine content was analyzed according to the method recommended by Xie et al. (2004). Tryptophan and other amino acids were determined according to the method supported by the State Bureau of Quality Technical Supervision of China (2000). Briefly, the methionine and cystine in sDDGS was oxidized in a mixture of 88% formic acid and 30% hydrogen peroxide (9:1) and then hydrolyzed at 110°C in 6 M HCl for 24 h. The pH of the hydrolysate was adjusted to 2.2 and it was then analyzed for methionine and cystine using an amino acid analyzer (L-8900, Hitachi, Tokyo, Japan). Tryptophan content was determined using alkali hydrolysis. The sample was hydrolyzed in 4 M LiOH at 110°C for 20 h, and then sodium citrate (pH 2.2) and 6 M HCl were added. After centrifugation at 1,520 g for 8 min at 4°C and filtration through a 0.22-µm filter membrane, the filtrate was analyzed by high-performance liquid chromatography (Agilent 1260, Santa Clara, CA, USA). The content levels of other amino acids were determined by ion-exchange chromatography with an amino acid analyzer (L-8900, Hitachi, Tokyo, Japan) after hydrolysis in 6 M HCl at 110°C for 24 h.
sDDGS TTTD Determination in Geese
Amino acid digestibility of sDDGS was determined using the Sibbald method with minor modifications (Sibbald, 1976). Briefly, 24 male Sichuan white geese (194 days old) with an average bodyweight of 3.5 kg were assigned to sDDGS treatment groups and a non-nitrogen treatment group according to their initial weight, with 12 replicates per treatment. Feathers within a 5-cm zone adjacent to the vent of the birds were removed to expose the skin and a special plastic retainer was sutured to the exposed skin. Birds were kept individually in metal cages (56×36×60 cm) and fed with a standard feed for 48 h. Birds subsequently assigned to the sDDGS and non-nitrogen treatment groups were fed sDDGS and corn starch diets (Table 2), respectively, ad libitum for 24 h. Following 24 h of fasting, individuals in the sDDGS-treatment groups were tube-fed 65 g of sDDGS diet (Table 2), and birds in the non-nitrogen treatment group were tube-fed 65 g of corn starch diet (Table 2). All geese had unrestricted access to drinking water, and light was provided for 24 h. To prevent damage to the mucosa of the esophagus during tube-feeding, water was added to the dietary pellets to produce a paste. At the time of tube-feeding, a bottle cut to a length of 3 cm with a collection bag was screwed to the sutured plastic lids for excreta collection, which lasted for 24 h. The metabolism cages with the experimental birds were put in artificial climate chambers with the temperature set at 24°C and the relative humidity at 60%. The light:dark (L:D) cycle was 16L:8D during the experimental period. Excreta samples were dried at 65°C for determination of energy and amino acids. The duration of the fasting period and the excreta collection period (24 h each) was chosen based on the study results of Sheng (2005). The methods used to determine energy and amino acids were identical to those used in Experiment 1.
Table 2.
Diet ingredients in Experiment 1 (% as fed)
| Item |
Diet |
| sDDGS |
Corn starch |
| sDDGS1 |
94.5 |
— |
| Corn starch |
— |
94.5 |
| Mineral and vitamin premix2 |
0.25 |
0.25 |
| Salt |
0.30 |
0.30 |
| Total |
100.00 |
100.00 |
1 sDDGS, sorghum dried distillers grains with solubles. The same as below.
2 Mineral and vitamin premix contained the following minerals in milligrams per kilogram of diet: Cu, 8; Fe, 85; Zn, 80; Mn, 85; Se, 0.3; and I, 0.4; and the following vitamins per kilogram of diet: vitamin A, 2500 IU; vitamin D3, 2000 IU; vitamin E, 10 IU; vitamin K
3, 2 mg; thiamine, 1.5 mg; riboflavin, 10mg; pyridoxine hydrochloride, 3 mg; cobalamin, 0.02 mg; pantothenic acid, 10 mg; nicotinic acid, 50 mg; folic acid, 1mg; biotin, 0.15 mg; and choline chloride, 1000 mg.
The true total tract digestibility(TTTD) of amino acids contained in sDsDGS was calculated as:
where AI
sDDGS is the total amino acid intake from the tube-fed sDDGS (g), AO
sDDGS-excreta is the total amino acid output in the excreta when tube-feeding sDDGS (g), and AO
corn starch-excreta is the total amino acid output in the excreta when tube-feeding corn starch (g).
sDDGS TME Determination in Geese
Twenty-four male Sichuan white geese were allotted to an sDDGS treatment group or a fasting treatment group for sDDGS true metabolizable energy(TME) determination. Following 24 h of fasting, the birds in the sDDGS treatment group were tube-fed 65 g of sDDGS diet (Table 2), while the birds in the fasting treatment group were fasted sequentially.
The experimental methods were identical to those used in amino acid digestibility estimation. The TME was calculated according to:
where GE
sDDGS is the gross energy of sDDGS (MJ/kg), GE
diet is the total energy intake from tube-fed sDDGS (MJ), GE
excreta is the total energy output in the excreta when tube-feeding sDDGS (MJ), and GE
fasting-excreta is total energy output in the excreta when fasting.
Experiment 3 examined the effect of sDDGS on the growth performance of geese. Three hundred and fifteen 35-day-old male Sichuan white geese with an initial average body weight of 1,732 g were randomly allocated to five treatments with seven replicate pens, each containing nine birds. Geese in each treatment group were fed one of five experimental diets: 0% sDDGS, 4% sDDGS, 8% sDDGS, 12% sDDGS, or 16% sDDGS. All diets were isoenergetic and isonitrogenous. The compositions and chemical analyses of the diets are shown in Table 3. Birds were kept in plastic-wire-floored pens with dimensions of 150×200×60 cm in an environmentally controlled duck house; the ambient conditions were room temperature and approximately 60% relative humidity. A stainless-steel feeder was used in the current experiment; the feeder's length, bottom width, upper width, inner height, and external height were 140, 12, 20, 12, and 18 cm, respectively. All birds had free access to pelleted feed and water, and the light program was 16 h of light per day. At 70 days of age, live weight gain for all geese was measured and recorded following 12 h of fasting; feed intake and feed/gain values were calculated throughout the experimental period. Feed intake and feed/gain were all corrected for mortality. Two geese were selected from each pen according to average bodyweight and killed by cervical dislocation. Breast meat (including pectoralis major and pectoralis minor), leg meat (including thigh and drumstick), subcutaneous fat and skin, and abdominal fat were removed from the two carcasses, weighed, and expressed as relative weight to live bodyweight at processing.
Table 3.
Ingredients and chemical composition of the diets (% as fed)
| Item |
Control |
4% sDDGS |
8% sDDGS |
12% sDDGS |
16% sDDGS |
| Ingredient |
|
|
|
|
|
| Corn |
51.50 |
53.23 |
55.48 |
57.82 |
60.10 |
| Soybean meal |
18.12 |
19.10 |
19.05 |
18.20 |
18.30 |
| Fish meal |
1.18 |
0.58 |
0.50 |
0.97 |
0.90 |
| sDDGS |
0.00 |
4.00 |
8.00 |
12.00 |
16.00 |
| Alfalfa meal |
21.00 |
15.72 |
10.60 |
5.71 |
0.50 |
| Soybean oil |
5.40 |
4.30 |
3.07 |
1.84 |
0.54 |
| Lysine·HCl |
0.11 |
0.14 |
0.15 |
0.16 |
0.18 |
| Dl-Methionine |
0.21 |
0.22 |
0.21 |
0.22 |
0.23 |
| L-Tryptophan |
0.05 |
0.06 |
0.09 |
0.07 |
0.08 |
| L-Threonine |
0.00 |
0.00 |
0.01 |
0.01 |
0.00 |
| L-Arginine·HCl |
0.11 |
0.11 |
0.13 |
0.15 |
0.14 |
| Salt |
0.30 |
0.30 |
0.30 |
0.30 |
0.30 |
| Limestone |
0.37 |
0.56 |
0.76 |
0.95 |
1.03 |
| Hydrophosphate |
1.40 |
1.44 |
1.40 |
1.35 |
1.45 |
| Mineral and vitamin premix1 |
0.25 |
0.25 |
0.25 |
0.25 |
0.25 |
| Total |
100.00 |
100.00 |
100.00 |
100.00 |
100.00 |
| Composition |
|
|
|
|
|
| Metabolizable energy (MJ/kg) |
11.95 |
11.95 |
11.95 |
11.95 |
11.95 |
| Crude protein |
16.00 |
15.99 |
15.99 |
16.00 |
16.00 |
| Crude fiber |
6.60 |
6.60 |
6.59 |
6.60 |
6.60 |
| Calcium |
0.85 |
0.85 |
0.85 |
0.85 |
0.85 |
| Phosphorous |
0.60 |
0.60 |
0.60 |
0.60 |
0.63 |
| Lysine |
0.85 |
0.85 |
0.85 |
0.85 |
0.85 |
| Methionine |
0.45 |
0.45 |
0.44 |
0.45 |
0.46 |
| Cystine |
0.23 |
0.23 |
0.23 |
0.23 |
0.23 |
| Threonine |
0.61 |
0.61 |
0.61 |
0.61 |
0.60 |
| Tryptophan |
0.25 |
0.25 |
0.28 |
0.25 |
0.25 |
| Arginine |
1.00 |
1.00 |
1.00 |
1.00 |
0.99 |
The goose performance data and carcass data were subjected to one-way analysis of variance (ANOVA) using the GLM procedure in SAS (SAS software 9.1.3). Differences were considered significant at P<0.05 and means were compared using Tukey's test. The experimental unit was the individual goose for energy and amino acid digestibility, and the replicate pen for the growth and carcass traits. The optimal dietary supplemental level of sDDGS was estimated using a broken-line regression model (Robbins et al., 2006) bythe NLIN procedure in SAS (Version 9.0): y=l+u(r−x); where y is the average daily feed intake, x is the dietary sDDGS level, u is the slope of the curve, r is the optimal dietary supplemental level of sDDGS, and l equals y when x is equal to r.
Results and Discussion
Chemical Composition of sDDGS
The chemical composition [as % drymatter (DM)] of sDDGS is shown in Table 1. The sDDGS composition was: crude protein, 15.48% DM; ether extract, 4.26% DM; and crude fiber, 31.46% DM. These results are generally lower than those in previous studies (Al-Suwaiegh et al., 2002; Urriola et al., 2009), which reported 32.9–35.9% for crude protein and 8.8–13% for ether extract. These discrepancies reflect the differences between the sDDGS materials used in the different studies. In the experiment of Al-Suwaiegh et al. (2002) and Urriola et al. (2009), sDDGS was produced from the fermentation of 100% sorghum, while the sDDGS used in our study came from a fermentation mixture of sorghum (95%) and rice hull (5%). The amino acid content (Table 3) of sDDGS ranged from 0.06–3.18%, indicating a low overall level of amino acids. The content levels of methionine, lysine, tryptophan, threonine, and arginine were 0.12, 0.41, 0.06, 0.45, and 0.42%, respectively, implying that sDDGS is deficient in essential amino acids for poultry. The crude protein and amino acid contents of sDDGS were higher than those of sorghum grain (Xiong et al., 2013) because of the conversion of grain starch to ethyl alcohol and CO2 during fermentation, which concentrated the remaining nutrients in the sDDGS. The levels of crude protein and ether extract in sDDGS were higher than those in corn, and were similar to those in wheat bran (Xiong et al., 2013). In addition, Table 1 shows that sDDGS contains a low level of energy, with a total energy value of 17.87 MJ/kg.
Table 1.
Chemical composition of sDDGS (as % DM)
| Item |
Content1 |
| Gross energy(MJ/kg) |
17.87 |
| Crude protein |
15.48 |
| Ether extract |
4.26 |
| Crude fiber |
31.46 |
| Calcium |
0.17 |
| Phosphorous |
0.25 |
| Amino acids |
|
| Methionine |
0.12 |
| Lysine |
0.41 |
| Valine |
0.70 |
| Leucine |
1.38 |
| Isoleucine |
0.54 |
| Threonine |
0.45 |
| Phenylalanine |
0.65 |
| Arginine |
0.42 |
| Histidine |
0.25 |
| Glycine |
0.53 |
| Proline |
1.22 |
| Serine |
0.58 |
| Cystine |
0.12 |
| Alanine |
1.03 |
| Glutamate |
3.18 |
| Tyrosine |
0.32 |
| Aspartate |
0.89 |
| Tryptophan |
0.06 |
1 Values are the means of three samples.
The digestibility of sDDGS by geese in terms of energy and amino acids was low (Table 4): the TME was 11.38 MJ/kg, and the TTTD of amino acids in sDDGS ranged from 43.16 to 80.92%. Among amino acids, the respective digestibilities of sDDGS methionine, lysine, tryptophan, threonine, and arginine for geese were 59.22, 43.16, 64.13, 58.59, and 59.94%. The digestibility of sDDGS has been estimated in previous studies of cattle (Lodge et al., 1997) and pigs (Urriola et al., 2009). However, to date, no data on the digestibility of sDDGS nutrients in poultry have been available. This means that the results of the current study will provide a reference for poultry feed formulation with sDDGS. sDDGS is a potential source of feedstuff for geese diets, but should be supplemented with high-energy or protein-rich ingredients.
Table 4.
Metabolizable energy and amino acid digestibility of sDDGS in geese
| Item |
Value1 |
| True metabolizable energy (MJ/kg) |
11.38 |
| True total tract digestibility of amino acids (% DM) |
|
| Methionine |
59.22 |
| Lysine |
43.16 |
| Valine |
61.61 |
| Leucine |
69.98 |
| Isoleucine |
61.88 |
| Threonine |
58.59 |
| Arginine |
59.94 |
| Phenylalanine |
67.07 |
| Histidine |
56.15 |
| Glycine |
55.14 |
| Proline |
65.10 |
| Serine |
68.17 |
| Cystine |
80.92 |
| Alanine |
73.47 |
| Glutamate |
55.14 |
| Tyrosine |
70.23 |
| Aspartate |
59.60 |
| Tryptophan |
64.13 |
1 Values are the means of 12 geese.
The inclusion of sDDGS in the diet did not affect (P>0.05) daily average weight gain (Table 5). These results are similar to those reported by Barekatain et al. (2013b), who found that bodyweight gain in the broiler chicken from 1 to 35 days was unaffected by inclusion of up to 30% sDDGS in the diet. As shown in Table 5, the average daily feed intake and feed-to-gain ratio of geese responded linearly to incremental dietary sDDGS incorporation (P<0.05). Birds that were fed up to at least 8% sDDGS had higher (P<0.05) average daily feed intake than geese fed the control diet, and the feed-to-gain ratio in geese fed diets containing 16% sDDGS was higher than in the control and the 4% sDDGS groups (Table 5). These results indicate that dietary inclusion of sDDGS increased feed intake and impaired the feed/gain ratio of the birds. These results are similar to those reported for broiler chickens by Barekatain et al. (2013b), who found that inclusion of 10–30% sDDGS in diets significantly increased feed intake and the feed/gain ratio in broiler chickens from 1 to 35 days. DDGS consists of a greater proportion of soluble nonstarch polysaccharides (NSP) (28.6 g soluble NSP/kg drymatter, 184.9 g insoluble NSP/kg drymatter) than the respective native grains; the presence of NSP increases digesta viscosity (Smits and Annison, 1996) and reduces the feed passage rate (Van der Klis et al., 1993), leading to lower growth rates and a higher feed/gain ratio. By contrast, xylanase supplementation in broiler chicken diets containing 30% sDDGS can improve the feed conversion ratio (Barekatain et al., 2013a, b), implying that appropriate supplementation with NSP enzymes could be beneficial to the feed efficiency of poultry diets containing sDDGS. In addition, the 5% rice hull content of sDDGS in the present study would have increased the indigestible dietary fiber and increased the feed/gain ratio. Our results suggest that up to 12% sDDGS can be included in the diet of geese aged 35–70 days without negative effects on body weight gain and the feed-to-gain ratio. Based on the broken-line regression model, the optimal dietary inclusion level of sDDGS for average daily feed intake was 12.86% (as fed) of diet [y=239.3−2.4325×(12.8551−x), R2=0.95, P=0.0248] in Sichuan white geese aged from 35 to 70 days.
Table 5.
Effect of sDDGS on performance of Sichuan white geese from 35 days to 70 days of age
1
| Item |
Control |
4% DDGS |
8% DDGS |
12% DDGS |
16% DDGS |
SEM2 |
P value |
| Weight gain (g/d per bird) |
50.1 |
49.3 |
52.9 |
51.0 |
49.7 |
0.52 |
0.211 |
| Feed intake (g/d per bird) |
209.8c |
214.3bc |
229.1ab |
237.3a |
239.3a |
3.09 |
0.001 |
| Feed/gain (g:g) |
4.20b |
4.35b |
4.49ab |
4.50ab |
4.81a |
0.06 |
0.011 |
a–c Means within a column with different superscripts are significantly different (P<0.05).
1 Values are the means of seven replicates of nine geese.
2 SEM, stand error of the mean.
In the present study, the yields of breast meat and leg meat were not affected (P>0.05) by dietarys DDGS level, and no differences (P>0.05) were observed for subcutaneous fat and skin, or abdominal fat across the five sDDGS treatments (see Table 6). This implies that dietary sDDGS inclusion up to 16% did not affect carcass yield. However, the dietary inclusion portion of sDDGS should be limited to avoid a negative effect on carcass yields. Dietary inclusion of DDGS (15 and 30%) did not affect dressing percentage and leg quarters percentage (to bodyweight) in broiler chickens aged 0–42 days, while a high level of incorporation (30%) reduced the ratio of breast to bodyweight in broiler chickens aged 0–42 days (Wang et al., 2007). In addition, Lukaszewicz and Kowalczyk (2014) reported that inclusion of 15% DDGS decreased the weight of breast muscle, leg muscle, and skin with subcutaneous fat, but did not affect their percentages relative to live bodyweight in chickens aged 0–42 days.
Table 6.
Effect of sDDGS on carcass characteristics of Sichuan white geese at 70 days of age
1, 2
| Item |
Control |
4% sDDGS |
8% sDDGS |
12% sDDGS |
16% sDDGS |
SEM3 |
P value |
| Breast meat (%) |
7.5 |
7 |
7.7 |
7.9 |
7.6 |
0.16 |
0.523 |
| Leg meat (%) |
10.8 |
10.4 |
10.7 |
11.2 |
10.4 |
0.17 |
0.597 |
| Subcutaneous fat + skin (%) |
14.5 |
15.1 |
15.7 |
14.9 |
14.4 |
0.26 |
0.538 |
| Abdominal fat (%) |
2 |
2.1 |
1.9 |
2 |
2.2 |
0.05 |
0.412 |
1 Values are the means of seven replicates of two birds.
2 The yield is calculated using the following equation: Yield = (breast meat, leg meat, subcutaneous fat + skin or abdominal fat weight) / live bodyweight at processing×100.
3 SEM, standard error of the mean.
sDDGS contains low levels of gross energy, crude protein, and amino acids, and a high level of crude fiber. The TME and TTTD of amino acids by geese were low. The average daily feed intake increased with increasing levels of sDDGS incorporation in the diet, and the optimal dietary inclusion level of sDDGS for average daily feed intake was 12.86% of diet based on our broken-line regression analysis. However, high levels (16%) of dietary sDDGS impaired the feed/gain ratio. Generally, sDDGS has potential for use as a valuable feedstuff for geese, but it should be supplemented with a high-energy or protein-rich ingredient. For improvements in growth performance and carcass yield, sDDGS levels below 12% can be included in the diets of geese from 35 to 70 days of age.
Acknowledgments
This work was supported bythe Special Fund for Agro-Scientific Research in the Public Interest (201303143), and the Earmarked Fund for China Agriculture Research System (CARS-42).
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