Partial replacement of maize with graded levels of corn cobs in pig weaner/grower diets

R.B. Fombad and F. Maffeja

Institute of Animal Research, Mankon Station
Bamenda, Cameroon

Abstract
Introduction
Materials and methods
Results
Discussion
Conclusion
Acknowledgements
References

Abstract

A study was carried out to investigate the effect of graded levels of corncobs as partial replacement of maize on the performance and carcass quality of weaner-grower Landrace pigs. Thirty two Landrace weaner pigs averaging 16.02 kg, initial liveweight were randomly assigned to four treatments with two replicates (2 females and 2 castrates/replicate) in a completely randomized design. Corn cobs were included at the levels of 0%, 10%, 20 and 30% in isoproteinous diets. The pigs were given feed on concrete floored pens and watered ad libitum through automatic nipple drinkers during a 12-week experimental period. Two pigs from each treatment (1 female and 1 castrate) were slaughtered for grading at the end of the experiment. Results showed significant differences (P<0.05) between treatments in average daily feed intake, daily weight gains and feed/gain ratios. When used up to 20%, corncobs offer the most efficient and cost-effective diet for pigs. When properly publicized, this ration can cut down feed cost to farmers.

Introduction

Increasing feed costs due to competition between man and animals for cereal grains has stimulated interest in ways of making use of agricultural by-products in the diets of monogastrics and ruminants. The North West and Western Provinces of Cameroon produce 3,080 metric tons of farm residues (corn stover, corncobs, rice straw, rice bran etc.) annually (Fomunyan, 1984).

Corncobs a widely available crop residue that when treated and used in pig feeding, it could reduce the cost of production and improve the quality of their carcasses.

Studies on ways of improving the digestibility of the high fibre content in corncobs abound in the literature. Beckman (1921) and Burrow (1980) (cited by Sundstol, 1981) have used several treatment methods (physical, alkali and microbiological to improve the digestibility of corncobs. These three main bonding methods are aimed to break the ligno-cellulose bonding thus increasing the digestibility of the roughage. Babatunde et al (1975) has recommended a level of up to 15% of corncobs in pig grower finisher diets. It was the aim of this study to see to what extent corncobs can efficiently replace corn in pig weaner/grower diets.

Materials and methods

Dried corncobs used in this study were collected from the Institute of Agronomic Research (IRA), at Bambui Station. The corncobs were ground into a meal and included at the levels of 0% (control group), 10%, 20% and 30% in isoproteinous diets (Table 1).

Thirty-two weaner landrace pigs averaging 16.02 kg liveweight were randomly assigned to 4 treatments with 2 replicates (2 females and 2 castrates/replicate). The pigs were treated for endoparasites, using "Exhelm" and for ectoparasites with "Tigal" and allowed one week adaptation period. They were group-fed ad libitum in concrete floored pens and water was given through automatic nipple drinkers during the 12-week experimental period.

Table 1. Composition of the experimental diets fed to weaner/grower pigs.

Ingredients	Levels of corncobs
	0%	10%	20%	30%
Corn	60	50	40	30
Corncobs	0	10	20	30
Fish meal	4	4	4	4
Cottonseed cake	14	16	16	16
Groundnut cake	12.5	12.5	14.5	16.5
Rice bran	7	5	3	1
Bone meal	1.5	1.5	1.5	1.5
Vitamin premix*	0.5	0.5	0.5	0.5
Salt	0.5	0.5	0.5	0.5
	100	100	100	100
Calculated analysis
Digestible energy (Kcal/kg)	3308.62	3209.48	2989.44	2834.52
Crude protein (%)	20.08	20.06	20.91	20.21
Crude fibre (%)	2.91	6.28	9.40	13.19
Calcium (%)	0.67	0.67	0.66	0.66
Phosphorus (%)	0.77	0.77	0.75	0.69
Lysine (%)	0.72	0.73	0.75	0.76
Methionine (%)	0.43	0.41	0.39	0.35

* A vitamin/mineral premix manufactured by BEAUTS Co. Inc. Man, U.S.A., to contain; Calcium 27%, Phosphorus 10%, Iron 0.6%, Zinc 0.35%, manganese 0.25%, Copper 0.06%; Iodine 0.002%, Cobalt 26 ppm, Selenium 4pp and per kg; Vitamin A 220,000, Vitamin D 66,000, Vitamin E 44, 014; Vitamin K 88 mg; Vitamin B 12; 0.76 mg; Niacin 1122 mg.

Pigs were weighed weekly and data on feed intake recorded. For carcass appraisal, two pigs (one female and one castrate) from each treatment were fasted for 18 hours during which they were given only water and were slaughtered the following morning. After chilling, the following carcass measurements were taken on the right side: length from the anterior edge of the first rib to the anterior edge of the aitch bone of the pelvis; back fat thickness opposite the first and last rib and last lumber vertebra; loin eye area, calculated from the tracing of the longissimus dorsi muscle sectioned at the tenth rib.

The percent lean cuts taken on the left side included percent ham, percent picnic shoulder, percent loin and percent Boston butt.

The economic approach of this study was assessed assuming all other cost rather than making feed constant throughout the experimental period of all treatments. Cost analysis of the feed used was carried out using current market prices of different ingredients. Statistical analyses were done according to methods of Steel and Torrie (1960).

Results

Data on growth performance of pigs is summarized in Table 2. Average daily feed intake decreased with an increase in the level of corncobs in diets although average daily gains declined with additional levels of corncobs. Pigs fed 0% and 10% levels of corncobs consumed significantly (P<0.05) more feed (1605 g and 1545 g) compared to intake (1354 g and 1343.5 g) of pigs with 20% and 30% levels of corncobs respectively. Weight gains for pigs with 0% and 10% levels were significantly higher (473 g/day and 451 g/day) than for pigs with 20% and 30% (340 g/day end 331 g/day) respectively. In terms of feed conversion, pigs fed 0% and 10% levels of corncobs were better converters compared to pigs fed 20% and 30% levels.

Table 2. Mean value of performance of pigs fed graded levels of corncobs.

	Levels of corncobs
Parameters	0%	10%	20%	30%	S.E.M.
Number of animals	8	8	8	8
Initial weight (kg)	16.06	16.06	16.06	15.96	1.85
Final weight (kg)	59.18a	56.93a	47.06b	47.81b	7.63
Daily feed intake (g)	1605a	1545ab	1355bc	1344c	116.0
Daily weight gains (g)	473a	451a	339.5b	330.8b	36.40
Feed/gain ratios	3.39a	3.53ab	3.99b	4.04b	0.22
Mortalities (number of pigs)	-	-	-	2	-

a, b, c = Means within each row not having common superscript are significantly different at (<0.05).

Table 3. Some carcass measurement of pigs fed diets containing graded levels of corncobs.

Parameters (%)	Levels of corncobs
	0%	10%	20%	30%	S.E.M
Carcass yield*(%)	67.9	69.3	67.8	65.2	1.84
Length (cm)	71.7	68.2	68.5	66.5	2.34
Back fat thickness (cm)	2.0a	2.0a	1.8a	1.2a	1.04
Loin eye area (cm)	16.9	18.3	16.4	16.0	2.03
Ham** (%)	30.5	28.2	29.6	30.4	1.84
Loin**(%)	33.4	31.0	31.4	30.8	1.84
Boston butt.**(%)	14.9	15.2	16.3	15.1	3.24
Picnic shoulder** (%)	17.9	16.0	18.9	16.6	0.32
Lean meat**(%)	58.6	58.6	60.2	61.9	0.81
Bones**(%)	14.7	14.7	14.8	14.2	0.81
Fats**(%)	20.1a	19.9a	14.3b	13.1b	1.40

* = expressed as percentage of liveweight
** = expressed as percentage of carcass weight
a, b, c = means within row not having common superscript are significantly different at (P<0.05).

Table 4. Cost and returns in feeding graded levels of corncobs to weaner/grower pigs

Parameter	0%	10%	20%	30%
Mean daily weight gain (kg)	0.473	0.451	0.340	0.330
Mean daily feed consumption (kg)	1.605	1.545	1.354	1.343
Feed converstion ratio	3.39	3.43	3.98	4.07
Feed cost (FCFA/kg)	113	107	102	97
Income (kg live weight FCFA)	382	367	407	391
Revenue/cost ratio	3.38	3.51	3.99	4.03
Net income over feed cost (FCFA/kg)	269	260	305	294

1 U.S. dollar = 295 FCFA.

Data on the effect of graded levels of corncobs on carcass yield are shown in Table 3. Pigs fed graded levels of corncobs had leaner carcasses than the pigs fed the control diet. The percentages of lean meat increased with the increase of the level of corncobs in the diets while the percentage of fat decreased. On the whole no significant differences were observed in the carcass yield obtained from each diet except for backfat thickness and percentage fat.

The estimated price of corncobs was 25 FCFA/kg and was based on transportation and processing costs. The cost of production of 1 kg of feed decreased as the level of corncobs in the diets increased. Economic data on feeding graded levels of corncobs to pigs is summarized in Table 4. Total feed cost (corncobs) including other ingredients was lowest (97 FCFA) for the diet with 30% corncobs but highest (113 FCFA) for the diet with no corncobs. Income was lowest 376 (FCFA/kg) liveweight in the diet with 10% and highest 407 (FCFA/kg) liveweight in the diet with 20% levels of corncobs.

Discussion

Data on the growth performance of pigs reveal that average daily feed intake decreased with increase in levels of corncobs in the diets compared to the control group. This decrease in feed intake is probably due to high levels of fibre content in the diets which made it unpalatable when compared to the control diet. These results agree with the findings of Kornegay (1978), and Cole et al (1967) which show that the pig can tolerate a wide range of crude fibre in the diet provided energy density is adequate. This shows that unless prevented by bulk or perhpas palatability the pig tends to eat until its energy requirement is fulfilled (Kornegay, 1978).

Average daily gains declined with additions of levels of corncobs. This declined in growth rate agrees with previous reports by Axelsson and Erickson (1953) when low nutritive value feed is fed to pigs.

Pigs fed 0% and 10% corncobs had feed intake, weight gains and efficiency of feed conversion significantly (<0.05) higher than pigs fed 20% and 30% levels of corncobs. Two mortalities were recorded in the group with 30% corncobs in their diet due to pronounced effect of vaginal prolapse. Female pigs fed tested diets showed vaginal prolapse. Picard, (Personal communication) attributed this effect to the level of fibre in the diet. This were probably so because the corn from which the corncobs were obtained was not treated with any chemical as the control group did not show the same sign.

Pigs fed graded levels of corncobs had leaner carcasses than the pigs fed the control diet. The percentage lean meat increased with an increase in the level of corncobs in the diets while the percentage of fats decreased. These findings are in agreement with the works of Hoefer et al (1963); Merkel et al (1958) and Salmela et al (1960) who reported that the production of lean pork carcasses can be achieved by replacing high energy feeds with bulky low energy feeds that are high in crude fibre or by the addition of inert materials such as corncob cellulose, sand and polyethylene in pig diets. Contrary to these studies are the works of Babatunde et al (1975) who reported marginal effects on carcass quality due to the fact that pigs had not sufficiently eaten high levels of fibre.

In terms of gains from production, the diet with 20% corncobs was the most profitable with a net income of 305 FCFA/kg liveweight while the diet with 10% corncobs was the least profitable test diet with a net income over feed cost of 266 FCFA. Although mean daily weight gain, feed consumption and feed cost decreased successively with increased levels of corncobs, diets with higher levels of corncobs did not necessarily yield a high income per kilogram liveweight. This was probably due to the similarity in the carcass that increased levels of corncobs significantly increased the percentage of lean meat which has a higher cash value.

The findings of this study indicate that corncobs can be fed to pigs at the level of 20% to get leaner carcasses. Corncobs are easily available in villages and can be ground in corn mills for incorporation in pig diets. Increased use of corncobs by peasant farmers could be enhanced by widespread dissemination of this technology by extension workers.

Although the extension service in Cameroon is not well-developed, formal and informal linkages can be made between large-scale corn producers and pig farmers to increase the supply of corncobs. Rural development organisations such as MIDENO (North West Development Authority), WADA (Wum Area Development Authority), PAFSAT (Promotion of Adaptive Farming Systems with use of Animal Traction) and UNVDA (Upper Nun Valley Development Authority) can incorporate these results into farm packages for distribution to farmers. The economic benefits of these results to farmers are substantial in terms of price and quality of meat produced. Whereas the price of corn fluctuates between 50 and 85 FCFA/kg as a result of supply and demand, the price of corncobs will almost invariably remain constant at 25 FCFA/kg under the same conditions. Apart from the price incentive for users of corncobs, maize producers will find a market for corncobs which would otherwise be wasted.

The other technologies used in this study which constitute concrete floors for pens, stone walls, automatic nipple drinkers are appropriate for a research station but this could easily be adapted to farmers' needs. They could have concrete floors containing drinking and feeding troughs and hard wood walls. Used motor vehicle tyres could be buried in pig fences as drinking troughs. This would be inexpensive to farmers.

Farmers in Cameroon generally own the land they cultivate. Since the construction of pens and the necessary infrastructure constitute long term investiment on the part of the farmers, land does not constitute a problem. In addition due to the fact that all the required inputs increase the chances of the adoption of the technology under discussion (i.e. improved feed for pigs), they will be able to gain more.

The efficient utilisation of the results of this study depends to a great extent on the education of the farmers. And since farmers will generally be willing to accept new technologies which they are convinced would serve their best interests, the impact of improved feed for pigs would greatly improve their production.

Conclusion

From the results obtained in this study corncobs can be used in weaner/grower pig diets to obtain more lean meat. When treated and fed, corncobs can enhance the growth performance of weaner/grower pigs. The diet is relatively easy to prepare and when used up to 20%, it offers the most efficient and cost effective diet for pigs. When properly disseminated, this ration can cut down on feed cost to farmers.

Acknowledgements

The authors gratefully acknowledge the help rendered by Messrs. Joseph Nyume and Joseph Awemo in the management of the experimental animals and collection of data. Gratitude is also expressed to Drs. R.T. Fomunyan and E. Tambi for their contributions and to MESIRES for providing funds for the study.

References

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