| Livestock Research for Rural Development 29 (5) 2017 | Guide for preparation of papers | LRRD Newsletter | Citation of this paper |
A total of 48 weaner and 24 grower-finisher Large White pigs at an average initial liveweight of 8.5 kg and 25 ± 0.5 kg respectively were used in feeding trials that aimed at investigating their performance with sun-dried based brewers spent grain (DBSG) diets. Pigs were randomly assigned to three dietary treatments designated as Control (W0), 17% DBSG (W 1) and 20% DBSG (W2) for the weaners while the grower-finisher pigs the designations were Control (GF0), 25% DBSG (GF1) and 30% DBSG (GF2). The pigs were grouped on the basis of sex and weight using a completely randomised design. The weaner and grower-finisher pigs had 16 and 8 animals of four replications per treatment respectively. They were restricted-fed once daily quantities of feed at 5% of bodyweights and water provided ad-libitum. They were weighed weekly and rations adjusted subsequently.
Growth parameters were recorded and carcass characteristics measured after pigs had been slaughtered at 60 ± 5 kg. The feed conversion ratios (FCR) during the weaner phase were 2.00, 2.08 and 2.50 for W0, W 1 and W2 respectively. Pigs fed W1 demonstrated significantly (P<0.05) preferred economy of gain of € 0.22 compared to their counterparts fed the other diets. The daily feed intake and FCR values of 1.61 kg and 3.78 were significantly lower (P<0.05) for grower pigs fed the GF0 diet relative to the values generated by those fed the other treatments. Much the same way, pigs fed GF1 diet generated the best (P<0.05) economy of gain value (€ 0.46) compared to the others. The fat parameters measured were inversely proportional to levels of DBSG included in the diets. The study demonstrated that the optimum inclusion rates of DBSG relative to weaner and grower-finisher diets were 17% and 25% respectively. It is more economical to raise pigs at these levels because it had the lowest feed cost per kg gain values.
Keywords: ad-libitum, agro-industrial by-product, brewery, carcass characteristic
Brewers Spent Grain (BSG) is one of the by-products from the brewery industry. It is readily available and cheap but the high moisture content (75-80%) puts a limitation on its shelf-life when kept in the raw state. In Ghana BSG has been found to contain an average crude protein of 21%, 16% CF, 7% EE, 3% Ash and 45.5% NFE (Rhule 2015). It is also a good source of water soluble vitamins (Muthusamy 2014). It has been reported severally in feeding livestock (Rhule 2015; Okai et al 1985; Ben-Hamed et al 2011). High inclusion of BSG in monogastric diets have been associated with decreased growth rate and nutrient digestibility as well as lower feed intake which were attributed to high fibre level (Wenjuan et al 2013; Amaefule et al 2006).
It is important that BSG is processed further in order to increase its shelf-life as well as evaluate its nutrient content. Several preserving methods have been proposed. Among which sun drying remains the most common method used by livestock farmers although it is difficult during the wet seasons (Rhule 2012 unpublished data). Dried Brewers Spent Grain at 25-40% in conventional diets for weaning and growing pigs could be fed to reduce feed cost without adverse effect on growth rate, carcass quality and organ characteristics (Imonikebe and Kperegbeyi 2014; Amaefule et al 2006). Most pig farmers in Ghana use sun-dried BSG as an ingredient in addition to other agro-industrial by-products such as cassava peels, palm kernel cake, maize bran to compound feed for their animals (Rhule, 2012 unpublished data).
The objective of the study was to determine the optimal inclusion rates of sun-dried BSG in weaner and grower-finisher pig diets composed with other non-conventional feed resources.
Brewers' Spent grain was freshly obtained from the Ghana Guinness Brewery Limited, Achimota. It was initially kept in an open space in a mound for two days for much of the liquid to drain off. It was then spread out on a thin layer of plastic polythene sheet and sun-dried over five (5) days. The DBSG was collected and stored for use in the diets. The mean temperature, relative humidity, wind speed recorded during drying was 28 °C, 65% and 12 km/hr respectively.
Forty-eight (48) Large White weaner pigs at an average initial liveweight of 8.5 kg were randomly distributed into three groups based on sex and liveweight using completely randomized design. The three groups were then randomly allotted to three dietary treatments so that there were sixteen (16) weaner pigs of four (4) replications per treatment.
The three dietary treatments were made up of Control diet (W0) and two other diets containing DBSG at inclusion of 17% (W1) and 20% (W2) respectively. The diets were made to be iso-nitrogenous and contained 18% CP. The composition of the diets is shown in Table 1. The pigs were restricted-fed once daily quantities of feed equivalent to 5% of each group live weight. Pigs were weighed weekly and the daily feed allocation adjusted. Water was provided ad libitum. The pigs were fed the diets till the attainment of an average live weight of 20 ± 2 kg.
Twenty-four Large White grower pigs made up of twelve intact males and twelve females at an average liveweight of 25 ± 0.5 kg were distributed into three groups based on sex and liveweight using the completely randomized design. The groups were then randomly assigned to one of three dietary treatments. Each dietary treatment had eight grower pigs with four replications.
The treatments were made up of three diets namely; Control diet (GF 0), diet with dried brewers spent grain at 25% (GF1) and diet with dried brewers spent grain at 30% (GF2). The compositions of the diets are shown in Table 2. Diets were made to contain 15% CP. The pigs were restricted-fed once daily quantities of diets equivalent to 5% of the liveweight. They were individually weighed weekly and the feed allowances adjusted accordingly. Water was provided ad libitum. The pigs were slaughtered on attaining an average liveweight of 60 ± 5 kg.
|
Table 1. Composition (%) of the weaner diets |
|||
|
Ingredients (%) |
W0 |
W1 |
W2 |
|
Maize |
45.3 |
- |
- |
|
Wheat bran |
35.0 |
- |
- |
|
Maize bran |
- |
25.7 |
20.8 |
|
Cassava peels |
- |
15.0 |
15.5 |
|
Brewers spent grain |
- |
17.0 |
20.0 |
|
Fish meal |
1.95 |
2.05 |
1.45 |
|
Soya bean meal |
15.0 |
15.0 |
14.5 |
|
Palm kernel cake |
- |
22.5 |
25.0 |
|
Oyster shell |
2.00 |
2.00 |
2.00 |
|
Salt |
0.50 |
0.50 |
0.50 |
|
Vit-min. premix# |
0.25 |
0.25 |
0.25 |
|
Total |
100 |
100 |
100 |
|
Calculated composition (%) |
|||
|
CP |
18.1 |
17.8 |
17.6 |
|
CF |
4.11 |
6.40 |
6.82 |
|
Ca |
0.91 |
0.84 |
0.82 |
|
P |
0.73 |
0.59 |
0.56 |
|
ME (MJ/kg) |
10.0 |
12.4 |
12.5 |
|
CP: ME ratio |
1.81 |
1.44 |
1.41 |
|
# Vit-min. Premix per 100kg diet: VitaminA (8x10 5U.I); VitaminD3 (1.5x104 U.I); VitaminE (250mg); VitaminK (100mg); VitaminB2 (2x102mg); VitaminB12 (0.5mg); Folic acid (50mg); Nicotinic acid (8x102mg); Calcium panthotenate (200mg); Choline (5x103mg). Trace elements: Mg (5x10 3mg); Zn (4x103mg); Cu (4.5x102mg); Co (10mg); I (100mg); Se (10mg). Antioxidants: Butylated hydroxytoluene (1x103mg). Carrier: Calcium carbonate q.s.p (0.25kg). |
|||
The pigs were housed in a cement-block building with concrete floors and it had corrugated aluminium roofing sheets. Internally, it had two rows of pens separated by a 110 cm wide aisle, which provided access to all the pens. Each pen measured 400 x 350 cm and had a 120 cm high dwarf walls. The pens had in-built feed and water troughs (170 x 40 cm) moulded with concrete on opposite walls.
Parameters considered were the average daily liveweight gain (ADG), feed conversion ratio (FCR), the economy of gain (EG) for both the weaner and grower-finisher phases. Indices for measuring carcass characteristics were taken on the left side of the slaughtered finisher pigs according to the Pork Carcass Evaluation and Procedures by Ray (2009).
The data collected were subjected to the general analysis of variance technique as described in the Genstat Discovery Edition (2008) and differences between treatment means determined by the Least Significant Differences.
|
Table 2. Composition (%) of the grower-finisher diets |
|||
|
Ingredients (%) |
GF0 |
GF1 |
GF2 |
|
Maize |
20.0 |
- |
- |
|
Wheat bran |
40.0 |
- |
- |
|
Maize bran |
- |
11.4 |
12.0 |
|
Cassava peels |
- |
22.6 |
19.0 |
|
Brewers spent grain |
- |
25.0 |
30.0 |
|
Fish meal |
1.00 |
1.95 |
1.20 |
|
Soya bean meal |
3.00 |
4.40 |
3.15 |
|
Palm kernel cake |
33.7 |
32.0 |
32.0 |
|
Oyster shell |
1.55 |
1.90 |
1.90 |
|
Salt |
0.50 |
0.50 |
0.50 |
|
Vit-min. premix# |
0.25 |
0.25 |
0.25 |
|
Total |
100 |
100 |
100 |
|
Calculated composition (%) |
|||
|
CP |
15.4 |
15.2 |
15.0 |
|
CF |
7.15 |
9.11 |
9.37 |
|
Ca |
0.68 |
0.70 |
0.73 |
|
P |
0.59 |
0.57 |
0.52 |
|
ME (MJ/kg) |
12.2 |
10.5 |
10.3 |
|
CP: ME ratio |
1.26 |
1.44 |
1.46 |
|
# Vit-min. Premix per 100kg diet: VitaminA (8x10 5U.I); VitaminD3 (1.5x104 U.I); VitaminE (250mg); VitaminK (100mg); VitaminB2 (2x102mg); VitaminB12 (0.5mg); Folic acid (50mg); Nicotinic acid (8x102mg); Calcium panthotenate (200mg); Choline (5x103mg). Trace elements: Mg (5x10 3mg); Zn (4x103mg); Cu (4.5x102mg); Co (10mg); I (100mg); Se (10mg). Antioxidants: Butylated hydroxytoluene (1x103mg). Carrier: Calcium carbonate q.s.p (0.25kg). |
|||
There was a significant difference (P<0.05) between the daily feed intakes by pigs fed the control as against DBSG diets. The corresponding mean values for the total feed intake at the end of the weaner phase were 27.9, 26.9 and 26.6 kg for dietary treatments W0, W1 and W2 respectively (Table 3).
Wo had low ME of 10.0 MJ/kg compared to 12.4 MJ/kg (W1) and 12.5 MJ/kg (W2). As pigs eat to meet their energy requirement, the low energy in the W0 diet could account for increase in feed intake, hence the results observed. Quiniou and Noblet (2012) studied the effect of dietary net energy (NE) concentration on feed intake and performance of growing-finishing pigs housed individually and observed that increase in dietary NE concentration was associated with a decreased average daily feed intake. Despite the high ME values in the DBSG diets, the ADG demonstrated by the pigs fed the diets were significantly (P<0.05) different among the dietary treatments with the control pigs showing the highest response relative to the rest. The crude fibre content (CF) of the diets increased with the inclusion of DBSG as well as the other AIBPs. The values were 4.11% (W0), 6.40% (W 1) and 6.82% (W2). Weaner pigs are known to have limited gut capacity as well as ability to utilize CF (Lindberg 2014). The anticipated influence of CF would be the reduced digestibility and availability of the nutrients in the diets for growth. It has been observed that for every 1% increase in CF there is an associated 1-3% decrease in digestibility of CP and energy (Schulze et al 1994).
With respect to the weaner pig, it appears the CP: ME ratio could also be very crucial. Despite the increase in the ME values of W1 and W 2, the CP: ME ratios were low compared to W0. For each unit of ME intake, there was adequate CP for tissue synthesis and growth as shown by the ADG of pigs fed the control diet (W0) compared to the others fed diets W1 and W2. It was noted that pigs fed diet W1 exhibited higher ADG than those fed W2 diet.
Constituents of W1 and W2, notably PKC had higher energy value than maize (Rhule 2015) as well as CF. The ADG observed for the weaner pigs seem to suggest that the CP: ME ratio must be given due cognizance and not merely the CP levels since the diets W0, W 1 and W2 had similar CP values. The mean FCR observed for the weaner pigs fed diets W0 and W1 were similar but significantly (P<0.05) better than pigs fed diet W2. The high fibre content of the W2 diet could have resulted in the poor growth (lower weight gain), hence the high FCR value. Rijal et al (2009) found that increasing levels of DBG in pigs' diets depressed feed intake and growth rate. The unit costs of the diets were € 0.13, € 0.11 and € 0.10 for the W0, W1 and W2 respectively. There was an inverse relationship between DBSG inclusion levels and feed cost per kg of the diets. Feed cost per kg gain (economy of gain) was best (P<0.05) for W1 compared to W2 which was in turn better (P<0.05) than W0.
Although, feed intake increased with increasing levels of the DBSG in the diets, average daily weight gain decreased with ADG of pigs fed diet GF 2 expressing significantly lowest of the dietary treatments (P<0.05) [Table 4]. This could be attributable to increasing CF in the GF1 and GF2. Yaakugh et al (1990) found that ADG decreased linearly as the level of DBSG increased and this was attributed to high dietary crude fibre intake.
|
Table 3. Growth performance of pigs during the weaner phase |
|||||
|
Parameter, kg |
W0 |
W1 |
W2 |
SEM |
P |
|
Initial weight |
8.56 |
8.58 |
8.55 |
0.19 |
0.25 |
|
Final weight |
22.5a |
21.6a |
19.2b |
0.80 |
<0.003 |
|
Weight gain |
13.9a |
13.0a |
10.7b |
0.79 |
<0.002 |
|
Daily weight gain |
0.41a |
0.38ab |
0.31b |
0.41 |
<0.001 |
|
Total feed intake |
27.9a |
26.9b |
26.6b |
0.48 |
<0.002 |
|
Daily feed intake |
0.82a |
0.79b |
0.78b |
0.02 |
<0.001 |
|
F.C.R (feed/gain) |
2.00a |
2.08a |
2.50b |
0.07 |
<0.002 |
|
Feed cost per kg (€) |
0.13 |
0.11 |
0.10 |
- |
- |
|
Feed cost per kg gain (€) |
0.27a |
0.22b |
0.26c |
0.13 |
<0.001 |
|
ø a,b, c- Means in a row with similar or no superscript are not significantly (P>0.05) different. |
|||||
The feed conversion ratios (FCR) recorded were 3.78, 4.13 and 4.34 for GF 0, GF1 and GF2 respectively. They were significantly different (P<0.05) from each other. This could be due to decreased ADG with increasing feed intake as the DBSG increased in the diets because FCR is a measure of how well an animal converts feed intake into liveweight gain. The unit cost of the feed decreased with increasing inclusion of DBSG (Table 4). This is similar to what was observed by Darkwa et al (2013) when total feed cost for rats significantly (P<0.05) decreased at higher level of DBSG (i.e. 30% DBSG/kg diet) inclusion.
|
Table 4. Feed intake, liveweight changes and FCE during the Grower-finisher phase |
|||||
|
Parameter, kg |
GF0 |
GF1 |
GF2 |
SEM |
P |
|
Initial weight |
24.6 |
24.7 |
24.6 |
0.06 |
0.51 |
|
Final weight |
64.2a |
63.2a |
60.1b |
1.08 |
0.97 |
|
Weight gain |
39.6a |
38.4a |
35.2b |
1.13 |
<0.003 |
|
Daily weight gain |
0.43a |
0.41a |
0.37b |
0.01 |
<0.001 |
|
Total feed intake |
146b |
158a |
154a |
3.55 |
0.63 |
|
Daily feed intake |
1.61b |
1.70a |
1.65a |
0.04 |
<0.002 |
|
F.C.R (feed/gain) |
3.78a |
4.13b |
4.34c |
0.12 |
<0.001 |
|
Feed cost per kg (€) |
0.12 |
0.11 |
0.11 |
- |
- |
|
Feed cost per kg gain (€) |
2.35b |
2.31a |
2.36b |
0.02 |
<0.002 |
|
ø a,b, c- Means in a row with similar or no superscript are not significantly (P>0.05) different. |
|||||
However, the feed cost could not influence the economy of gain. The grower-finisher pigs fed GF1 diet had significantly (P<0.05) better economy of gain than those fed GF0 and GF2 diets. The study indicated that FCR could be very crucial in the profitability of production over the unit cost of feed.
|
Table 5. Mean carcass characteristics of grower-finisher pigs fed BSG diets |
|||||
|
Parameter ( kg) |
GF0 |
GF1 |
GF2 |
SEM |
P |
|
Warm dressed weight |
41.9a |
39.4b |
37.4b |
0.72 |
0.53 |
|
Chilled dressed weight |
40.6a |
38.2b |
36.0c |
0.73 |
0.51 |
|
Carcass length |
66.9 |
66.4 |
65.8 |
1.34 |
<0.002 |
|
Loin eye area |
20.0 |
21.8 |
21.5 |
0.97 |
<0.002 |
|
Fillet |
0.31 |
0.31 |
0.30 |
0.01 |
<0.001 |
|
Respiratory tract |
1.08 |
1.05 |
1.06 |
0.02 |
<0.001 |
|
Head |
4.40 |
4.23 |
4.13 |
0.14 |
<0.002 |
|
Trotters≠ |
0.90 |
0.89 |
0.87 |
0.03 |
<0.001 |
|
Viscera |
9.59 |
9.60 |
8.98 |
0.25 |
<0.003 |
|
Full G.I.T |
7.00 |
6.64 |
6.62 |
2.18 |
0.39 |
|
Empty G.I.T |
2.53 |
2.64 |
2.41 |
0.17 |
<0.002 |
|
Heart |
0.22 |
0.22 |
0.21 |
0.01 |
<0.001 |
|
Kidney≠ |
0.21 |
0.21 |
0.20 |
0.02 |
<0.001 |
|
Thigh |
6.06 |
6.00 |
5.86 |
0.90 |
0.18 |
|
Shoulder |
3.66 |
3.64 |
3.43 |
0.11 |
<0.002 |
|
Loin |
5.32 |
5.52 |
5.16 |
0.47 |
0.34 |
|
Backfat thickness (cm) |
2.56a |
2.11b |
2.01b |
0.12 |
<0.002 |
|
Leaf fat |
0.77b |
0.68a |
0.65a |
0.62 |
<0.002 |
|
P2 measurement (cm) |
2.04a |
1.73b |
1.69b |
0.89 |
<0.003 |
|
ø
a,b- Means in a row with similar or no superscript
are not significantly (P>0.05) different. |
|||||
Table 5 shows the carcass characteristics of pigs fed the three different diets. There were no significant differences (P>0.05) in all the carcass parameters studied except the warm and chilled dressed weights as well as the fat parameters such as backfat thickness, P2 and leaf fat which were significantly (P<0.05) influenced. Increasing DBSG in the diet resulted in decreased final weight, warm and chilled dressed weights. In all, pigs fed GF0 had the highest relative to the rest. Pigs fed GF1 and GF2 diets had significantly (P<0.05) lower backfat thickness, P2 and leaf fat compared with those fed the GF0 diet. The fat parameters were inversely proportional to the levels of dried brewers’ grain in the diets. This suggests that pigs fed the DBSG diets used much of their feed energy for muscle tissue than fat deposition. Amaefule et al (2006) observed a similar trend when they fed pigs with high levels (30, 35 and 40%) of brewers’ dried grain diets in the humid tropics. Darkwah et al (2013) also observed similar trend when growing pigs were fed with dried brewers’ spent grains (DBSG) supplemented with an exogenous enzyme. They observed that backfat thickness was inversely proportional to the levels of brewers’ dried grain in the diets.
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Received 28 January 2017; Accepted 12 March 2017; Published 1 May 2017