| Livestock Research for Rural Development 30 (1) 2018 | Guide for preparation of papers | LRRD Newsletter | Citation of this paper |
The apparent total tract digestibility (ATTD), nitrogen retention, gut environment and gut organ size was studied in Moo Lath (ML) and Large White (LW) growing pigs fed un-fermented and fermented cassava root pulp and soybean pulp. The experiment was arranged according to a 2 × 4 factorial design with two breeds (ML and LW pigs) and four diets (UCLP, FCMP, SPMP and SPHP). Diet UCLP was a low-protein diet with un-fermented cassava root pulp, diet FCMP was a medium-protein diet with fermented cassava root pulp, diet SPMP was a medium-protein diet with soybean pulp and diet SPHP was a high-protein diet with soybean pulp. A total of 32 pigs (16 ML and 16 LW), aged 2 months old were allocated to metabolism cages throughout 12 days comprising 7 days for adaptation and 5 days for data collection. All diets were fed ad libitum.
Dry matter intake (DMI) was higher in LW than in ML pigs, and DMI was higher in diets SPMP and SPHP than in diets UCLP and FCMP.
The ATTD of organic matter (OM) and crude protein (CP) did not differ between breeds. The ATTD of OM was highest on diet SPHP followed by diet SPMP and diets FCMP and UCLP. The ATTD of CP was highest on diet SPHP and lowest on diet UCLP with diets FCMP and SPMP being intermediate.
Nitrogen (N) retention (g/day and % of N intake) differed between breeds, while N retention expressed as a proportion of N digested was similar between breeds. N retention (g/day and % of N intake) was highest in diet SPHP followed in descending order by diets SPMP, FCMP and UCLP. In contrast, N retention expressed as a proportion of N digested was highest in diet FCMP followed in descending order by diets SPHP, SPMP and UCLP.
Empty stomach weight (g/kg body weight) was higher in ML than in LW pigs, while empty caecum weight (g/kg body weight), length (cm/kg body weight) of small intestine, caecum, colon + rectum and total intestinal length were greater for LW than ML pigs.
In conclusion, fermenting cassava root pulp with a commercial yeast-product, rice bran and urea increased the CP content and improved the N digestibility and N retention in both ML and LW pigs. Moreover, N utilization (N retention in % of N digested) on the diet with fermented cassava root pulp was comparable to the diets supplemented with soybean pulp.
Key word: fermentation, gut environment, nitrogen balance, yeast
Feed supply for mono-gastric animals has increasingly become a challenge for small-holder farmers in developing countries. The main reason for this is that traditional major feed ingredients for these animals (i.e. cereals, roots, tubers, soya beans and fish) are also important staple foods for humans (Sansoucy 1995). As a result, these feed ingredients become expensive and scarce. Thus, it is urgent to find alternative feed ingredients that can complement or replace the more traditional ones.
Cassava (Manihot esculenta crantz) is widely grown in the tropical region. The cassava root is an excellent source of dietary energy, but low in protein, and is commonly used in pig diets throughout the world (Gomez 1992). It can be fed fresh, dried or ensiled. A major concern with the use of cassava products as animal feed are the toxic cyanides found in the form of the cyanogenic glucoside linamarin (Gomez 1992; Tewe 1992). However, proper processing of cassava roots (e.g. sun-drying, ensiling, grating, soaking, and fermentation) will reduce the cyanide content to non-toxic levels (Tewe 1992).
The residue after starch extraction of the cassava root is a cheap and potentially useful feed ingredient for small-holder farmers in the tropics. However, replacement of other feed ingredients for cassava root products in the diet will reduce the protein supply due to their low protein content. Therefore, protein enrichment of cassava roots and their products would markedly increase their potential nutritive value as a feed ingredient. Microbial fermentation has been identified as one of the less expensive means of increasing the protein content and quality of cassava (Balagopalan et al 1991). Recently, Boonnop et al (2009) showed that yeast (Saccharomyces cerevisiae) fermentation of fresh cassava root pulp and cassava chips increased the content of crude protein (CP), true protein, and lysine and reduced the content of cyanide.
Soy bean (Glycine max) is the globally most common and most important oil seed used in livestock feeding. It is an excellent source of both energy and protein, and has a balanced amino acid profile to meet the amino acid requirements for mono-gastric animals (e.g. pigs and poultry) (Baker 1999). One factor of major concern is the anti-nutritional factors present in soybeans (e.g. protease inhibitors and lectins). However, both protease inhibitors and lectins are inactivated by moist heat treatment of soy products (Liener 1999). The residue after soy-milk extraction of the soy bean is cheap and potentially useful feed ingredients for small-holder farmers.
The aim of this study was to evaluate the impact on apparent total tract digestibility, nitrogen retention, gut environment and visceral organs in Moo Lath (ML) and Large White (LW) growing pigs when feeding diets with unfermented cassava root pulp, fermented cassava root pulp and soybean pulp. It was hypothesized that yeast fermentation of cassava root pulp should improve the protein quality, and that Moo Lath pigs should be superior to Large White pigs in digesting the fibre-rich diets.
The experiment was carried out at the Integrated Farming Demonstration Center of Champasack University, Lao PDR. The temperature in the area ranges from 23 to 32°C. The experiment was carried out from 10 May to 1 June 2016.
The cassava root pulp was a by-product from a starch factory situated about 11 km from the integrated farming demonstration center of Champasack University and was steamed for 25 minutes and cooled to room temperature. After that it was mixed (8 g/2 kg of fresh cassava root residue) with a commercial yeast-product (Luang Ha yeast, Quynh Trang Company, Quang Tri, Vietnam), rice bran (200 g/2 kg of fresh cassava root pulp) and urea (20 g/2 kg of fresh cassava root pulp) as nitrogen source and fermented for 7 days in a container (capacity 2 kg in DM). The container was an open vessel to let the air come in and was put into plastic buckets to exclude mice and prevent external mechanical damage. It was stored in room temperature (20-30oC).
Soybean pulp was a by-product from farmer’s homemade soybean milk in Pakse city. A total of four experimental diets were prepared (Table 1), a low-protein diet with unfermented cassava root pulp (UCLP), two medium protein diets supplement either with fermented cassava root pulp (FCMB) or soybean pulp (SPMP) and a high protein diet supplemented with soybean pulp (SPHP).
The feed ingredients (Table 2) were stored in plastic bags to avoid moisture entering before mixing the diets. The diets were mixed every day and put into plastic bags in order to maintain the quality of the feed and avoid mould. The diets were offered in the mash form.
|
Table 1. Ingredient composition (g/kg DM) of the experimental diets |
||||
|
Ingredients |
UCLP# |
FCMP* |
SPMP§ |
SPHP ѕ |
|
Rice bran |
460 |
460 |
600 |
480 |
|
Broken rice |
100 |
100 |
100 |
100 |
|
Soybean pulp |
- |
- |
100 |
220 |
|
Cassava root pulp |
- |
- |
200 |
200 |
|
UCRB## |
440 |
- |
- |
- |
|
FCRB** |
- |
440 |
- |
- |
|
Chemical composition, % |
||||
|
Dry matter |
68.5 |
59.4 |
67.9 |
68.6 |
|
Ash |
14.5 |
13.8 |
13.7 |
13.5 |
|
Total CP |
9.6 |
12.4 |
14.1 |
16.5 |
|
# UCLP: unfermented cassava root pulp-low protein; *FCMP: fermented cassava root pulp-medium protein, SPMP: Soy bean pulp-medium protein; ѕ SPHP: Soy bean pulp-high protein;## Unfermented cassava root pulp mixed with yeast and rice bran;**Fermented cassava root pulp mixed with yeast, urea and rice bran. |
||||
A total of 32 pigs, 16 Moo Lath (ML) and 16 Large White (LW) were used in the experiment. The ML pigs were bought from farmers in Champasack Province, and the LW pigs were bought from a private farm in the city. They were 60 days old, and the initial body weight (BW) of ML pigs was 7.5 kg and the LW pigs were 13.7 kg. Before the experiment started, all animals were vaccinated against Hog cholera, and de-wormed with Ivermectin (1 mL/20 kg BW). The pigs were kept individually in metabolism cages (0.66 m × 0.63 m × 0.60 m), elevated 0.6 m from the ground and allowing the separate collection of faeces and urine. The cages were made of bamboo and wood, and provided with feeders, and automatic water drinkers. The animals had free access to water.
|
Table 2. Chemical composition of the ingredients |
|||
|
|
DM, % |
CP, % DM |
Ash % DM |
|
Rice bran |
88.4 |
14.0 |
15.2 |
|
Broken rice |
89.2 |
8.3 |
6.9 |
|
Soybean pulp |
19.3 |
40.4 |
9.1 |
|
Cassava root pulp |
15.5 |
1.8 |
1.0 |
|
UCRB## |
17.1 |
2.6 |
1.2 |
|
FCRB** |
35.7 |
16.1 |
13.8 |
|
##
Unfermented cassava root pulp mixed with yeast and
rice bran; |
|||
The experiment was structured according to a 2×4 factorial design with two breeds (ML and LW) and four diets (UCRB, FCRB, SPMP and SPHP). The animals were selected from six litters (three litters for ML and three litters for LW), and the experiment was performed in four periods using four animals per breed per diet and period. Each period lasted for twelve days, seven days for adaptation and five days for collection for data. The feed was given in equal amount twice per day at 8:00 and 16:00 hours. Remaining feed was removed and weighed before fresh feed was added.
The total amount of feeds offered and residues, faeces and urine were recorded daily during the last 5 days of each period. In addition, samples of faeces were collected twice daily 3-4 hours after each meal from the plastic under the metabolism cage. The collected faeces were stored at -18°C until analysis, samples from each pig and period were pooled. Urine was collected in a plastic bucket to which sulphuric acid were added to maintain the pH below 4.0 (10 mL of solution of 10% of concentrate sulphuric acid). The volume of urine was measured every day and 10% of the total volume was collected and stored until analysis. The pigs were weighed in the morning before feeding at the beginning and the end of each period.
On day 13 of the experiment, two to three hours after the morning feeding, the pigs were weighed and then killed by injection of Thiopental (20 mg/kg BW), for assessment of gut environment and morphometric measurement of visceral organs. The gastrointestinal tract (GIT) was removed and segmented into stomach, small intestine, caecum and colon plus rectum. The removal of GIT started from the anus using scissors to remove each segment in turn (rectum, colon, caecum, small intestine and stomach). Segments of full and empty digestive tract were weighed, and the length of each segment section of intestine was recorded. Digesta was collected from ileum (about 60 cm of small intestine before the ileo-caecal ostium) and colon (20 cm from the caecum) and immediately transferred to plastic bags, frozen at -20°C and kept frozen until preparation for analysis.
Urine samples were analysed for total nitrogen (N) only in fresh form by micro-Kjeldahl method (AOAC, 1990). Feed and faeces sample were analysed for dry matter (DM) by micro-wave radiation (Undersander et al 1993). Ash and CP (total N) were analysed according to standard methods (AOAC, 1990). The pH was measured by a pH meter (PHM 92, Radiometer, Copenhagen, Bergman and Beving). The organic acids (short chain fatty acids (SCFA) and lactic acid) were analysed accordingly. The digesta samples were centrifuged for 5 minutes at 16,000 × g and 600 µL of the clear solution was mixed with 800 µL of the internal standard solution (0.1% of pivalic acid in 5 mM sulfuric acid). The analysis of organic acids in the samples was performed according to Andersson and Hedlund (1983) by a high-performance liquid chromatography (HPLC) system consisting of the following: Alliance 2795 Separations module with a temperature control module II range of 0 to 150°C, a 2414 RI detector (Waters Association), a separation column (ReproGel H; 9µ volume; 300 by 8 mm) and a precolumn packet (ReproGel H; 9 µ volume; 30 by 8 mm; Dr. Maisch HPLC GmbH, Ammerbuch, Germany). The mobile phase was 5 mM sulphuric acid at a flow rate of 0.8 mL min-1, and the column temperature was kept at 60°C.
CP content was calculated as N × 6.25. Organic matter (OM) content was calculated as 100 – Ash. DM intake (DMI) was calculated as total intake – feed residue, digested N was calculated as 100 × (N intake – N in feces)/N intake, total N retention was calculated as N intake – N in faeces – N in urine, and relative N retention was calculated as ((N retention/N intake) ×100) and ((N retention/N digested) x 100). Relative organ weight was calculated as g organ/kg BW and the empty organ/kg BW.
The data were analysed as 2×4 factorial design with diet, breed and interaction (diet by breed) as factors using the general linear model (GLM) procedure of Minitab Software, version 16 (Minitab, 2010). The treatment means which showed significant differences at the probability level of p<0.05 were compared using Tukey’s pairwise comparison procedure.
The following model was used to analyse treatment effects on digestibility:
Yijk= µ + Di + Bj + (D i × Bj) + eijk
Where:
Yij= is the nutrient digestibility; µ = is the overall mean; D i = is the effect of diet i; Bj = is the effect of breed j; (Di × Bj) = is the interaction between diet i and breed j; eijk= is the random error.
DMI differed between ML and LW pigs and between diets. There was an interaction in DMI between diet and breed. The highest DMI was recorded on diets SPHP and SPMP (Table 3). For the interactions, there were no differences in DMI between UCLP, FCMP and SPMP for the ML pigs. However, a higher intake were recorded when ML pigs were fed the SPHP diet.
There were no breed differences in the apparent total tract digestibility (ATTD) of OM and CP (Table 3). The ATTD of OM and CP differed between diets with highest values for OM in diet SPHP followed in descending order by diet SPMP and diets FCMP and UCLP. Diet SPHP had the highest ATTD of CP followed in descending order by diets SPMP and FCMP, and diet UCLP.
|
Table 3. Effect of dietary treatment (D) and breed (B) on apparent total tract digestibility (ATTD), nitrogen balance and nitrogen retention in Moo Lath (ML) and Large White pigs (LW) pigs. Results are presented as mean value for breed and dietary treatments ± pooled standard error of mean (SEM) |
||||||||||
|
Items |
Breed |
Dietary treatments* |
SEM |
P |
||||||
|
ML |
LW |
UCLP |
FCMP |
SPMP |
SPHP |
B |
D |
B × D |
||
|
DMI, g/day |
259 |
510 |
239b |
224b |
481a |
593a |
35.6 |
0.001 |
0.001 |
0.13 |
|
Digestibility, % |
||||||||||
|
OM |
73.7 |
76.0 |
62.7c |
65.4c |
82.9b |
88.2a |
1.85 |
0.22 |
0.001 |
0.58 |
|
CP |
74.3 |
76.1 |
63.5c |
74.6b |
75.7b |
87.1a |
1.67 |
0.22 |
0.001 |
0.45 |
|
N balance, g/day |
||||||||||
|
N intake |
5.9 |
10.4 |
3.7c |
4.5c |
10.4b |
11.9a |
0.78 |
0.001 |
0.001 |
0.25 |
|
N in feces |
2.0 |
1.2 |
1.4b |
1.1b |
2.4a |
1.8a |
0.22 |
0.001 |
0.002 |
0.78 |
|
N in urine |
1.2 |
2.1 |
1.1b |
1.0b |
2.6a |
1.9a |
0.21 |
0.001 |
0.001 |
0.29 |
|
N retention |
||||||||||
|
N retention, g/day |
2.7 |
7.1 |
1.2b |
2.4b |
5.4a |
6.9a |
0.47 |
0.001 |
0.001 |
0.03 |
|
N retention, % of total N intake |
46 |
68 |
32c |
53b |
52b |
58a |
1.36 |
0.03 |
0.001 |
0.12 |
|
N retention, % of digested N |
69 |
77 |
52c |
71a |
68b |
68b |
2.01 |
0.24 |
0.001 |
0.38 |
|
* For diet abbreviations, see Table 1. |
||||||||||
N intake, N in urine and N retention (g/day and % of N intake) was higher in LW than ML pigs while N in feces was higher in ML than in LW pigs (Table 3). N retention (% of N digested) did not differ between breeds. N intake, N in feces and N in urine were higher on diets SPHP and SPMP than on diets FCMP and UCLP. N retention (g/day and % of N intake) was highest in diet SPHP followed in descending order by diets SPMP, FCMP and UCLP (Table 3). N retention (% of N digested) was highest on diet FCMP followed in descending order by diets SPHP and SPMP, and diet UCLP.
|
Table 4. Effect of breed (B) and dietary treatment (D) on full and empty organ weight (g/kg live weight) in Moo Lath (ML) and Large White (LW) pigs. Results are presented as mean value for breed and dietary treatments ± pooled standard error of mean (SEM) |
|||||||||||||
|
Items |
Breed |
Dietary treatments* |
SEM |
p |
|||||||||
|
ML |
LW |
UCLP |
FCMP |
SPMP |
SPHP |
B |
D |
B x D |
|||||
|
Full digestive organ weight, g/kg live weight |
|||||||||||||
|
St |
62.9 |
64.2 |
65.8 |
56.6 |
69.1 |
62.5 |
5.05 |
0.79 |
0.36 |
0.36 |
|||
|
SI |
67.8 |
69.0 |
70.8 |
63.2 |
69.3 |
70.4 |
5.17 |
0.81 |
0.71 |
0.51 |
|||
|
Ce |
8.2 |
10.6 |
12.8 |
7.0 |
8.5 |
9.4 |
2.20 |
0.29 |
0.31 |
0.61 |
|||
|
Co+Re |
49.8 |
60.4 |
56.0 |
58.0 |
54.8 |
51.7 |
3.23 |
0.29 |
0.31 |
0.66 |
|||
|
Total GIT |
188.7 |
204.2 |
205.4 |
184.8 |
201.7 |
194.0 |
8.79 |
0.09 |
0.38 |
0.37 |
|||
|
SI/LI |
1.4 |
1.2 |
1.3 |
1.1 |
1.3 |
1.4 |
0.10 |
0.06 |
0.33 |
0.96 |
|||
|
Empty digestive organ weight, g/kg live weight |
|||||||||||||
|
St |
14.2 |
11.7 |
12.8 |
12.6 |
13.8 |
12.7 |
0.68 |
0.01 |
0.53 |
0.73 |
|||
|
SI |
42.1 |
42.6 |
42.8 |
39.7 |
42.9 |
44.0 |
2.73 |
0.88 |
0.71 |
0.48 |
|||
|
Ce |
1.95 |
2.62 |
2.6 |
1.7 |
2.7 |
2.2 |
0.34 |
0.05 |
0.16 |
0.98 |
|||
|
Co+Re |
20.9 |
21.7 |
20.1 |
21.5 |
21.4 |
22.2 |
1.62 |
0.61 |
0.84 |
0.62 |
|||
|
Total GIT |
79.1 |
78.6 |
78.3 |
75.4 |
80.8 |
80.9 |
3.67 |
0.88 |
0.68 |
0.37 |
|||
|
SI/LI |
2.1 |
2.0 |
2.3 |
1.9 |
2.1 |
2.0 |
0.20 |
0.72 |
0.66 |
0.90 |
|||
|
Organ weight, g/kg live weight |
|||||||||||||
|
Liver |
31.5 |
27.1 |
30.9 |
28.9 |
27.6 |
29.8 |
1.65 |
0.01 |
0.56 |
0.15 |
|||
|
Kidney# |
4.4 |
4.7 |
4.3 |
4.8 |
4.3 |
4.8 |
0.41 |
0.45 |
0.70 |
0.05 |
|||
|
Heart |
4.5 |
5.7 |
4.6 |
5.1 |
4.8 |
5.9 |
0.65 |
0.09 |
0.54 |
0.96 |
|||
|
* For diet abbreviations, see Table 1; ** St=stomach; SI=small intestine; Ce=caecum; Co=colon; Re=rectum; TI=total intestine; LI=large intestine; GIT=gastrointestinal tract; SI/LI=small intestine/large intestine; For diets, means with different letters within a row are different (P<0.05); #Mean values for interactions in kidney: UCLP_ML: 4.4b ;UCLP_LW:4.1b; FCMP_ML:5.1a; FCMP_LW:4.3b; SRMP_ML:4.2b; SRMP_LW:4.5b; SRHP_ML:3.6c; SRHP_ML:5.9a;**Ratio SI/LI= ratio small intestine/large intestine. |
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Higher relative empty caecum weight was recorded for LW compared with ML pigs (Table 4), whereas the ML pigs had higher relative empty stomach weight than the LW pigs. Moreover, the ML pigs had higher relative liver weight than LW pigs. Interestingly, an interaction between breed and diet were observed for relative kidney weight. The ML pigs had the highest relative kidney weight on the FCMP diet and the lowest on the SPHP diet. In contrast, the LW pigs had the highest relative kidney weight on the SPHP diet but there were no differences when they were fed the other diets.
|
Table 5. Effect of breed (B) and dietary treatment (D) on length of intestine in Moo Lath (ML) and Large White (LW) pigs. Results are presented as mean value for breed and dietary treatments ± pooled standard error of mean (SEM) |
||||||||||
|
Items** |
Breed |
Dietary treatments* |
SEM |
p |
||||||
|
ML |
LW |
UCLP |
FCMP |
SPMP |
SPHP |
B |
D |
B x D |
||
|
Intestine length, cm |
||||||||||
|
SI |
896 |
1313 |
1132 |
1032 |
1121 |
1133 |
63.1 |
0.001 |
0.62 |
0.90 |
|
Ce |
9 |
13 |
12.9 |
9.3 |
10.8 |
10.5 |
0.93 |
0.001 |
0.08 |
0.51 |
|
Co+Re |
198 |
242 |
228 |
180 |
225 |
245 |
18.6 |
0.003 |
0.11 |
0.72 |
|
TI# |
1103 |
1568 |
1373 |
1221 |
1357 |
1389 |
69.4 |
0.001 |
0.32 |
0.81 |
|
SI/LI |
4.8 |
5.8 |
5.0 |
6.4 |
5.1 |
4.8 |
0.65 |
0.14 |
0.31 |
0.94 |
|
Intestine length, cm/kg live weight |
||||||||||
|
SI |
120 |
94 |
108 |
102 |
110 |
107 |
7.9 |
0.003 |
0.90 |
0.62 |
|
Ce |
1.2 |
0.9 |
1.2 |
0.9 |
1.1 |
1.0 |
0.10 |
0.005 |
0.45 |
0.89 |
|
Co+ Re |
26.8 |
17.5 |
22.9 |
18.1 |
23.8 |
23.8 |
2.71 |
0.002 |
0.40 |
0.61 |
|
TI# |
148 |
112 |
132 |
121 |
135 |
132 |
9.5 |
0.001 |
0.74 |
0.56 |
|
SI/LI |
0.7 |
0.4 |
0.5 |
0.7 |
0.5 |
0.5 |
0.07 |
0.03 |
0.21 |
0.87 |
|
* For diet abbreviations, see Table 1; ** SI=small intestine; Ce=caecum; Co=colon; Re=rectum; TI=total intestine; LI=large intestine; SI/LI=small intestine/large intestine; #Length of total intestine included length of small intestine, caecum and colon + rectum; For diets, means with different letters within a row are different (p<0.05). |
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The length of small intestine, caecum and colon + rectum and total intestine length (cm) were greater for LW than for ML pigs (Table 5). However, the relative length (cm/kg body weight) of corresponding parameters and the ratio of small intestine/large intestine relative length were greater for ML than LW pigs. No effect of diet or interaction between diet and breed were observed for any of the above mentioned parameters.
Pigs fed diet FCMP had the highest proportion of propionic acid in ileal digesta followed by pigs fed diet UCLP, and diets SPMP and SPHP (Table 6). No effects of diet, breed and the interaction of diet and breed were observed for pH, concentration (mmol L-1) of lactic acid or SCFA in ileal digesta.
In colon digesta, pigs fed diets SPMP and SPHP had higher pH than pigs fed diets FCMP and UCLP and pigs fed diet SPHP had higher concentration (mmol -1) of iso-valeric acid than pigs fed diet FCMP (Table 7). LW pigs had higher concentration (mmol L-1) of n-valeric acid in colon digesta than ML pigs. Furthermore, ML pigs had higher molar proportion (%) of acetic acid in colon digesta than LW pigs.
|
Table 6. Effect of breed (B) and dietary treatment (D) on concentration of organic acids (mmol L-1), molar proportion (%) of short chain fatty acid (SCFA) and pH in the ileal digesta of Moo Lath (ML) and Large White (LW) pigs. Results are presented as mean value for breed and dietary treatments ± pooled standard error of mean (SEM) |
||||||||||
|
Items** |
Breed |
Dietary treatment* |
SEM |
p |
||||||
|
ML |
LW |
UCLP |
FCMP |
SPMP |
SPHP |
B |
D |
B x D |
||
|
LA, mmol L-1 |
38.4 |
41.6 |
40.8 |
20.5 |
46.0 |
52.6 |
10.35 |
0.76 |
0.18 |
0.47 |
|
pH |
7.0 |
7.0 |
7.0 |
7.1 |
7.1 |
6.8 |
0.10 |
0.75 |
0.23 |
0.27 |
|
SCFA, mmol L-1 |
||||||||||
|
HAc |
2.9 |
2.5 |
1.3 |
1.1 |
4.1 |
4.2 |
1.29 |
0.76 |
0.18 |
0.95 |
|
HPr |
1.2 |
1.0 |
1.0 |
1.3 |
1.1 |
1.1 |
0.17 |
0.36 |
0.36 |
0.46 |
|
HiBu |
1.2 |
1.6 |
1.2 |
1.0 |
1.6 |
1.7 |
0.26 |
0.15 |
0.17 |
0.78 |
|
HBu |
1.3 |
1.6 |
1.5 |
1.0 |
1.6 |
1.7 |
0.42 |
0.60 |
0.66 |
0.67 |
|
HiVa |
1.0 |
1.0 |
1.0 |
1.0 |
1.0 |
1.0 |
- |
- |
- |
- |
|
HVa |
1.0 |
1.0 |
1.0 |
1.0 |
1.0 |
1.0 |
- |
- |
- |
- |
|
Total OA |
47.0 |
50.2 |
47.8 |
27.0 |
56.4 |
63.2 |
9.60 |
0.74 |
0.07 |
0.36 |
|
Total SCFA |
8.9 |
8.6 |
7.0 |
7.1 |
10.3 |
10.6 |
1.66 |
0.86 |
0.26 |
0.84 |
|
SCFA, mol % |
||||||||||
|
HAc |
24.0 |
24.6 |
18.2 |
16.7 |
30.7 |
31.5 |
5.25 |
0.91 |
0.11 |
0.93 |
|
HPr |
15.0 |
13.2 |
15.0b |
17.8a |
11.9c |
11.5c |
1.51 |
2.25 |
0.02 |
0.93 |
|
HiBu |
15.4 |
18.7 |
16.7 |
15.2 |
18.2 |
18.1 |
2.58 |
0.21 |
0.82 |
0.80 |
|
HBu |
15.7 |
17.6 |
20.1 |
15.2 |
15.3 |
16.0 |
1.66 |
0.53 |
0.58 |
0.71 |
|
HiVa |
13.8 |
13.0 |
15.0 |
15.2 |
11.9 |
11.5 |
1.14 |
0.61 |
0.18 |
0.52 |
|
HVa |
13.8 |
13.0 |
15.0 |
15.2 |
11.9 |
11.5 |
1.14 |
0.61 |
0.18 |
0.52 |
|
* For diet abbreviations, see Table 1; For diets, means with different letters within a row are different (p<0.05).**LA=lactic acid, HAc=acetic acid, HPr=propionic acid, HBu=n-butyric acid, HiBu=iso-butyric acid, HVa=n-valeric acid, HiVa=iso-valeric acid, OA=organic acids. |
||||||||||
|
Table 7. Effect of breed (B) and dietary treatment (D) on concentration of organic acids mmol L-1, pH and molar proportion (%) of short chain fatty acids (SCFA) in the colon digesta of Moo Lath (ML) and Large White (LW) pigs |
||||||||||
|
Items** |
Breed |
Dietary treatment* |
SEM |
p |
||||||
|
ML |
LW |
UCLP |
FCMP |
SPMP |
SPHP |
B |
D |
B x D |
||
|
LA, mmol L-1 |
3.1 |
2.6 |
2.8 |
2.1 |
3.3 |
3.3 |
0.51 |
0.34 |
0.28 |
0.41 |
|
pH |
5.8 |
5.7 |
5.6b |
5.6b |
5.9a |
5.7ab |
0.07 |
0.09 |
0.02 |
0.41 |
|
SCFA, mmol L-1 |
||||||||||
|
HAc |
47.7 |
48.2 |
43.4 |
45.4 |
50.8 |
52.1 |
6.04 |
0.94 |
0.71 |
0.40 |
|
HPr |
25.1 |
27.5 |
28.8 |
20.1 |
29.6 |
26.8 |
3.02 |
0.44 |
0.17 |
0.90 |
|
HiBu |
1.7 |
1.9 |
2.4 |
1.0 |
2.9 |
1.0 |
1.19 |
0.83 |
0.60 |
0.31 |
|
HBu |
10.3 |
14.0 |
12.9 |
11.5 |
10.9 |
13.3 |
1.56 |
0.03 |
0.69 |
0.55 |
|
HiVa |
3.2 |
3.1 |
3.1ab |
2.7b |
3.3ab |
3.6a |
0.18 |
0.36 |
0.03 |
0.10 |
|
HVa |
1.4 |
3.0 |
2.4 |
2.3 |
1.7 |
2.6 |
0.47 |
0.002 |
0.55 |
0.88 |
|
Total OA |
92.6 |
100.5 |
95.9 |
85.1 |
102.5 |
102.6 |
9.89 |
0.44 |
0.60 |
0.99 |
|
Total SCFA |
89.5 |
97.8 |
93.1 |
82.9 |
99.2 |
99.3 |
9.57 |
0.40 |
0.63 |
0.99 |
|
SCFA, mol % |
||||||||||
|
HAc |
53.0 |
48.0 |
46.9 |
54.6 |
50.7 |
50.8 |
2.45 |
0.05 |
0.19 |
0.40 |
|
HPr |
27.7 |
28.3 |
30.6 |
24.5 |
29.7 |
27.3 |
1.55 |
0.72 |
0.06 |
0.49 |
|
HiBu |
1.8 |
1.9 |
2.3 |
1.2 |
2.6 |
1.1 |
0.98 |
0.93 |
0.62 |
0.30 |
|
HBu |
11.8 |
15.1 |
14.0 |
13.8 |
11.6 |
14.4 |
1.67 |
0.06 |
0.65 |
0.53 |
|
HiVa |
3.8 |
3.2 |
3.4 |
3.2 |
3.6 |
3.9 |
0.40 |
0.14 |
0.68 |
0.76 |
|
HVa |
1.6 |
3.0 |
2.6 |
2.7 |
1.7 |
2.5 |
0.49 |
0.001 |
0.20 |
0.53 |
|
* For diet abbreviations, see Table 1; abc For diets, means with different letters within a row are different (p<0.05). **LA=lactic acid, HAc=acetic acid, HPr=propionic acid, HBu=n-butyric acid, HiBu=iso-butyric acid, HVa=n-valeric acid, HiVa=iso-valeric acid, OA=organic acids. |
||||||||||
Fermenting cassava root pulp with rice bran and urea for seven days increased the DM content from 17.1 to 35.7 % and the CP content from 2.6 to 16.1%. The increase in DM was contradictory to Manivanh and Preston (2016) who explained an increased CP content in yeast fermented cassava root by DM loss. However, the DM content was similar to the 30.4% that was reported by Huu and Khammeng (2014) for yeast fermented cassava pulp. The CP content in the fermented cassava pulp in the present study and the study by Manivahn and Preston (2016) was in the same range (16.1 and 16.7%). Several other studies have also shown that fermenting cassava products with yeast or fungi increases the CP content, reduces the HCN content and thereby increase the nutritive value (Huu and Khammeng 2014; Boonnop et al 2009; Bayitse et al 2015; Hong et al 2017). However, the CP content in the fermented products differs among the cited studies (12.5-32.5%). The difference can be related to differences in source of cassava, kind of yeast and nitrogen source used. In the present study, cassava root pulp, urea and a commercial yeast-product was used. The yeast source included in the commercial yeast-product was not specified and remains un-known. Ngoc et al (2012) reported that cassava pulp mainly was composed of starch (563 g/kg DM) and fibre (NDF 405 g/kg DM), which can provide enough solubilized carbohydrates for efficient fermentation. The proportion of true CP in the fermented diet (FCMP) was not determined. However, the improved retention of digested N in diet FCMP compared with the un-fermented diet (UCLP), and a similar retention of digested N with the soybean pulp diets, suggest a marked improvement of the CP quality in the fermented protein-enriched product.
The pigs used in the present study were both of the local ML breed and the exotic LW breed, of which the latter are known to have a higher growth potential. The results showed higher DMI for the LW pigs, which can be linked to their higher body weight and higher daily BW gain. Generally, the pigs showed higher DMI when they were fed the soybean pulp than the cassava root pulp, indicating a higher palatability of the soybean pulp. This was line with a previous study (Phoneyaphon and Preston 2016) showing that feed intake was higher when the protein supplement was soybean meal compared with ensiled taro or cassava foliage.
There were no differences between LW and ML pigs in OM and CP digestibility. However, for N balance (g/day and % of total N), higher values were found for the LW pigs. Moreover, an interaction between diet and breed was also observed with the highest N retention for LW pigs fed diet SPHP. This could partly be linked to differences in CP requirements. According to Phengsavanh and Lindberg (2013) the CP requirement of ML is 15% for growers, which is lower than the 18% CP recommended by NRC (2012) for growers. In this study only the ML pigs fed the SPHP diet were fed above requirements, which explain the superior response to increased protein content for LW pigs. Interestingly, no differences between breeds were observed when the N retention was expressed as % of digested N, which indicate that the higher DMI in LW pigs contributed to the observed differences in N balance. Moreover, differences between diets in both digestibility and N balance were observed. The urinary N excretion was lower on the cassava root pulp diets compared with the soybean pulp diets. A decreased urinary N excretion will decrease the ammonia emission inside and outside the farm (Lynch et al 2008).
The improved ATTD of CP between diets UCLP and FCMP can partly be explained by higher CP content in diet FCMP, and partly by an improved protein quality due to transformation of N sources to yeast protein. The improved ATTD of CP between diets SPMP and SPHP can also partly be explained by higher CP content, and partly by an improved protein quality due to higher inclusion of soybean pulp in the diet. For both OM and CP digestibility, diet SPHP was superior and diet UCLP inferior, with diets SPMP and FCMP being intermediate. The difference in OM digestibility was likely the result of rice bran inclusion, where diet SPHP had the lowest inclusion. Rice bran is a high fibre product, with the main part of the fibre being insoluble (Ngoc et al 2012), which is negatively correlated to diet energy digestibility. Noblet and Le Goff (2001) reported an energy digestibility coefficient of rice bran in growing pigs of 0.56. The difference in digestibility between diets UCLP and FCMP was assumed to be due to degradation of the fibre fraction during the fermentation process and transformation of the degraded fibre to easily digestible protein by the yeast. This is supported by the fact that the N retention (in % of digested N) was highest in the FCMP diet. This was in agreement with Manivanh and Preston (2016) who reported that the coefficient of digestibility of OM and CP increased with increasing levels of protein-enriched cassava root (PECR) in the diet. In this study, the range of values for retained N in diet FCMP (2.7 to 6.9 g/day) were lower than that reported by Manivanh and Preston (2016; 6.1 to 8.7 g/day). However, N intake on diet PECR (8.9 to 11.5 g/day) in the study by Manivanh and Preston (2016), was higher than the present study (2.9 to 6.1 g/day).
There were no effects of diet on the visceral organ weight and length, which can be explained by the short experimental periods. However, there were several differences in visceral organ traits between breeds. For the absolute weights and lengths, the LW pigs had greater values than ML pigs. However, when weights and lengths were expressed per kg body weight many of those differences disappeared. Thus, the higher body weight of LW pigs explains a major part of the differences in absolute visceral organ weights and lengths between breeds. However, some differences between the breeds in relative visceral organ measurements were observed such as higher stomach and liver weight in ML pigs and higher caecum weight in LW pigs. Similar results on organ parameters were found by Kaensombath et al (2013), with a higher dressing percentage for the LW than the ML pigs. This was explained by a higher genetic potential for lean meat production (Affentrager et al 1996).
Organic acids are the main end product of microbial fermentation of the GIT with lactic acid dominating in the proximal parts and acetic acid in the distal parts (Jensen 2001), which also was observed in the present study. Furthermore, the relative proportion of organic acids can be affected by the dietary composition (Jensen 2001). Interestingly, pigs fed the FCMP diet differed from pigs fed the other diets with regards to the proportion of propionic acid, with higher proportion in ileum digesta. Hong and Lindberg (2007) showed that the content of organic acids were higher in fermented compared to cooked and raw diets resulting in a higher proportion of acetic acid, lactic acid and propionic acid in ileal digesta. A higher dietary intake of organic acids for pigs fed diet FCMP in the present study may be related to the observed higher proportion of propionic acid in ileum. In colon digesta, pigs fed diet SPHP had higher concentration of iso-valeric acid than pigs fed diet FCMP. This indicates higher protein fermentation in the hindgut on the SPHP diet, since the branched-chained fatty acids are degradation products of branch-chained amino acids (Williams 2001). The higher values on SPHP could be linked to the higher N intake on that diet. The lower values on the FCMP further support the previous suggestion on improved protein quality in the fermented cassava root pulp.
There were also differences between breeds in gut environment. Firstly, the LW pigs had higher concentration of n-butyric acid and both higher concentration and proportion of n-valeric acid in colon digesta, whereas ML pigs had higher proportion of acetic acid in colon digesta. Apart from the dietary composition, the microbial composition is an important factor affecting the gut environment. Interestingly, Benson et al (2010) concluded that host genetics is an important factor shaping the gut microbial composition. It is therefore likely that the microbial composition in colon were different in LW and ML pigs which can explain the observed differences in gut environment.
This study was financed by Sida-SAREC (Swedish international Development Cooperation Agency- Department for research Cooperation), through the regional MEKARN program and the Swedish University of Agricultural Science. The authors would like to thanks the researchers in the Department of Animal Nutrition and Management, Swedish University of Agricultural Science and staff and student of Champasack University for their help in carrying out the study.
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Received 1 December 2017; Accepted 23 December 2017; Published 1 January 2018