Growth performance and nutrient digestibility of growing pigs fed a mixture of palm kernel meal and cassava peel meal

A A Fatufe*, I O Akanbi, G A Saba, O Olowofeso and O O Tewe

Department of Animal Science, University of Ibadan, Ibadan.
*Department of Animal Science, Obafemi Awolowo University, Ile-Ife.
aafatufe@oauife.edu.ng   ;   andrewfatufe@yahoo.com

Abstract

In  a 42 days feeding trials, twenty growing crossbred pigs with mean initial body weights of 16 ± 0.8kg were assigned randomly to 5 dietary treatment groups of four pigs each.  A basal diet was formulated. The basal diet was based on cassava flour, maize offals, soyabean meal and brewer’s dried grain (BDG). A mixture of cassava peel meal and (CPM) and palm kernel meal (PKM) replaced the BDG fraction in the basal diet in the ratio 2:0, 0:2, 1:1 and 1.75:1.75 in diets II, III, IV and V respectively. Each diet was offered on ad libitum basis. Pigs were individually weighed on weekly basis until the end of the experiment. Daily voluntary feed intake was monitored.

Growing pigs responded non-significantly (p> 0.05) to the mixture of different fibre sources in body weight gain, feed conversion ratio and protein efficiency ratio except for feed intake, which varied significantly (p< 0.05). Data on final body weight was described using the linear regression method. The slope of regression of final body weight (y) (kg/pig/week) depending on weeks (kg/week) was highest on diet V (3.525 ± 0.1842) and lowest on diet II (2.074 ± 0.1742). Digestibility values also varied significantly (p< 0.05) with ether extract having the average digestibility value (%) of 90.32 and ash the lowest value of 53.60.

Key words: dietary fibre, additivity, efficiency of utilisation, weight gain

Introduction

The use of agro-industrial byproducts for livestock feeding especially in the developing countries is seen a measure for sustainable livestock development. Palm kernel meal (PKM) and Cassava peel meal (CPM) as individual ingredients have been extensively studied for various monogastric species including poultry, pigs and rabbits (Okoye et al 2006; Onifade and Babatunde 1998; Perez et al 2000). Palm kernel meal is a by-product of red palm oil industry. It is a common feed ingredient used in practical pigs feeding. Cassava peel meal is also a by-product of cassava processing industry. It is also extensively used in pig feeding in Nigeria.

Palm kernel meal and cassava peel meal are agro-industrial by-product used mainly as fillers in livestock feeding. Studies are usually conducted on individual ingredients in separate experiments, and experiments in which these fibres are compared together are rare.  Even though various experiments have been conducted on these two individual feedstuffs to evaluate their potentials as livestock feeds, experiments designed to systematically detect any possible additive and associative effects that may result from feeding them in combination are rare. It is often assumed that the effect of feeding them in combinations is additive. Some additive studies on conventionally feedstuff have been studied in pigs and poultry (Angkanaporn et al1996; Furuya and Kaji 1991), but studies are rare for unconventional feedstuff. The objective of the present study is to compare the efficiency of utilisation of the two fibre sources in varying proportions for growth in growing pigs.
 

Materials and methods

Experimental diets

Fresh cassava peels were obtained from local cassava processing industry in Ibadan. Cassava peels were spread on concrete floor and sun dried for approximately 5 days depending on the intensity of sunlight. This was later milled with a hammer mill at the feed mill of the Teaching and Research farm, University of Ibadan. Other conventional ingredients were obtained from local feed mills in Ibadan.

A basal diet was formulated. The basal diet was formulated to meet the nutrient requirement of growing pigs (NRC 1998) on total nutrient basis and adjusted for nutrient requirement of pigs raised under tropical environment. The basal diet was based on cassava flour, maize offals, soyabean meal and brewer’s dried grain (BDG). Table 1 shows the gross composition of the experimental diets.

A mixture of cassava peel meal (CPM) and palm kernel meal (PKM) replaced the BDG fraction in the basal diet in the ratio (CPM/PKM): 2:0, 0:2; 1:1 and 1.75:1.75 in diets II, III, IV and V respectively. The calculated concentration of metabolisable energy in the basal diet was 10.29 MJ/kg, based on raw material data for poultry. 20 growing pigs with average initial body weight of 16 ± 0.8kg (Mean ± SEM) were assigned to the five dietary treatments. Each diet was offered to 4 pigs housed 2 pigs per pen. In the planning of this experiment, having more animals per replicate as opposed to using individual animals as replicates seems appropriate to us. Feed was offered on ad libitum basis. Water was also provided unrestrictedly. Pigs were individually weighed on weekly basis until the end of the experiment. Daily voluntary feed intakes were monitored. Feed intake and consequently feed conversion could not be separated for individuals and are therefore calculated as pen averages. The experiment lasted for 42 days. At the end of the feeding trial, 10 animals were selected for total tract digestibility study. 3 days adjustment period was allowed and 4 days collection period was observed.

Statistical and chemical analyses 

Dry matter, crude protein, crude fibre, ether extract and ash contents of feed and excreta samples were performed according to the AOAC (1990) procedure. Data were subjected to routine ANOVA from General Linear Model procedures using the software package SPSS 11.0 for windows. Data were also subjected to Levene’s test (to test for equality of variance) from the same software. Non-linear models did not fit our data better than linear regression on growth of pigs [y, kg/pig] depending on weeks [x, growth over time] therefore a linear regression was calculated.

y = a + bx

where a =constant and b=slope of the regression line.

Treatment averages were considered as one data point in the regression analysis. Parameter of goodness of fit were r² and  Sy.x. The Sy.x values are the standard deviations of the residuals, which are the distances between the individual points from the calculated line. The experiment was conducted on the Teaching and Research Farm, University of Ibadan, Ibadan. 

Results

Growth trial 

The gross and proximate compositions of the test diets are shown in Table 1 and Table 2 respectively.

Calculated chemical composition (proximate analysis) of treatment diets are in agreement with analytical values. Table 3 shows the performance of pigs fed the test diets.

Growing pigs responded non-significantly (p> 0.05) to the mixture of the two fibre sources in body weight gain, feed conversion ratio and protein efficiency ratio except for feed intake, which varied significantly. The average final body weights (kg/pig) ranged from 28.10 to 37.66, while the actual weight gain recorded also ranged from 12.57 to 21.23 for the treatment groups. Feed intake on Diet V was significantly highest (p<0.05) than all other diets, while feed intake on Diet II was significantly lowered (p<0.05). Table 4 shows the estimated parameters of the final body weight of pigs fed the test diets.

The slope of regression of final body weight depending on weeks was highest on diet V and lowest for diet II (Table 4; Figure 1).

The slope of regression of the different diets ranked V > I >III >IV > II.  Diet V was superior (p> 0.05) to the other combinations in terms of growth performance.

Digestibility trial 

Digestibility values varied significantly (p< 0.05) with ether extract having the average digestibility value (%) of 90.32 and ash the lowest value of 53.60 (Table 5).

The apparent fibre digestibility was significantly highest in Diet 2 and lowest in Diet 3. Dry matter digestibility was also significantly affected by fibre source with Diet 3 having the highest value and Diet 2 the least value, while the mixed fibre sources diets having intermediate values. This picture is also true for crude ash, ether extract and crude protein with either Diet 2 or 3 taking the lead and the mixed fibre sources being intermediate. Nitrogen free extract was unaffected.
 

Discussion

Growth performance of growing pigs

The inclusion rates of PKM and CPM in the experimental diet were in line with those reported in literature for optimal performance (Adeleye 1992; Rhule 1996).  Single supplementation of PKM in Diet 3 gave a comparatively similar result in terms growth performance indices to those reported in literature for growing pigs of the same weight range (Jegede et al 1994; Rhule 1996).  Growing pigs were able to utilise PKM efficiently in this diet without any loss in performance.  Feed intake was significantly depressed on the single supplementation of CPM in Diet 2 at 20% inclusion rate. This must have resulted in the observed lowered body weight gain observed on this treatment group. Feed conversion was however not affected. Since the basal diet was based on cassava flour, it appears that the threshold value of 40% of cassava inclusion rate, which may cause decline in performance, is already been approached (Iyayi 1986). This observation is also in line with those reported in literature (Adeleye 1992). This is usually due to the cyanide content of some cassava varieties.

Various methods of detoxifying cassava-based diets have been proposed to stem the feed depression usually resulting from high inclusion rates, which include methionine and vegetable oil supplementations to ameliorate the effect of high cyanide ingestion, by livestock species (Tewe 1992). However, the main objective of this study is to assess the additivity of these two fibre sources. An equal ratio of CPM and PKM at 20% inclusion rate in Diet 4 resulted in a similar feed intake to that of Diet 2. Since dry matter intake is the primary determinant of nutrient supply, the observed lower performance on Diet 4 may be a direct consequence of CPM inclusion levels.  Performance indices of pigs on Diet 4 were numerically better than those on Diet 2. However, an equal combination of PKM and CPM at 35% inclusion level resulted in better growth performance. The slope of regression of final weight gain depending on week gave a better indicator of efficiency of utilisation of these two dietary fibre sources. The slope of regression was higher for Diet V than diet IV, which implies that growing pigs responded to increased supplementation of both fibre mixes in the same magnitude. The slope of the regression curve suggests additivity effect when the two fibres are fed in combination.

Nutrient digestibility in growing pig

The apparent fibre digestibility was significantly highest in diet 2 and lowest in diet 3 which are the 20% single supplementations of CPM and PKM respectively. This is interesting because one would have expected this improved fibre digestibility on Diet 2 to translate into better feed conversion efficiency and consequently a better growth rate in growing pigs. Dry matter digestibility was also significantly affected by fibre source.         

This confirms our earlier submission that the depressed feed intake on the CPM diet might have been responsible for the lower numerical growth rate observed on this diet compared to others (0.30 vs. 0.45 kg/pig/day). CPM inclusion enhanced ash digestibility while PKM inclusion decreases it with intermediate values for the fibre mixes.

Conclusions 

• Feeding PKM and CPM in combination produced a better growth performance than feeding CPM alone and result suggests additivity effect based on the slopes of the regression curve of the final body weight of pigs on diets IV and V.
   

References

Adeleye A A 1992 Physiological responses of pigs fed graded levels of cassava (Manihot esculenta crantz) peel in maize based diet. Ph. D thesis, University of Ibadan, Ibadan

Angkanaporn K, Ravindran V and Bryden W L 1996 Additivity of apparent and true ileal amino acid digestibilities in soybean meal, sunflower meal, and meat and bone meal for broilers. Poultry Science 75:1098–1103. 77:149–163

AOAC 1990 Official methods of analysis. Association of official analytical chemists, 15^th edition., Washington DC, USA

Furuya S and Kaji Y 1991 Additivity of the apparent and true ileal digestible amino acid supply in barley, maize, wheat or soya-bean meal based diets for growing pigs. Animal Feed Science and Technology 32:321–331

Iyayi E A 1986 Effect of varying protein levels on the performance of growing pigs. Ph.D thesis, University of Ibadan, Ibadan

Jegede J O, Tegbe T S B, Aduku A O and Olurunju S A S 1994 The effect of feeding palm kernel meal on performance and carcass characteristics of pigs. Nigeria Journal of Animal Production 21: 88-95

NRC 1998 Nutrient requirement of swine. Tenth revised edition. National Academy Press, Washington, DC

Okoye F C, Ugwuene M C and Mbarah J U 2006 Effects of local spices on the utilization of cassava peel meal-based diets by weaner rabbits. Pakistan Journal of Nutrition 5 (3): 203-205

Onifade A A and Babatunde G M 1998 Comparison of the utilisation of palm kernel meal, brewers' dried grains and maize offal by broiler chicks.  British Poultry Science  39:245-50

Perez J F, Gernat A G and Murillo J G 2000 Research notes: The effect of different levels of palm kernel meal in layer diets. Poultry Science 79: 77-9 http://ps.fass.org/cgi/reprint/79/1/77.pdf

Rhule S W A 1996 Growth rate and carcass characteristics of pigs fed on diets containing palm kernel cake. Animal Feed Science and Technology 61: 167-172

Tewe O O 1992 Detoxification of cassava products and effects of residual toxins on consuming animals. Proceedings of FAO Expert consultation held at CIAT, Cali, Colombia, 21-25, January 1991. Editors: D Machin and S Nyrold  http://www.fao.org/docrep/003/T0554E/T0554E06.htm

Received 21 June 2007; Accepted 25 September 2007; Published 11 December 2007

Go to top