African Journals Online
Ghana Journal of Agricultural Science

VOLUME 31 (1998) PART TWO
CONTENTS

ABSTRACTS

MAGGOT MEAL AS A SUBSTITUTE FOR FISH MEAL IN LAYING CHICKEN DIET

(O. J. A.: Department of Animal Science, Delta State University, Asaba Campus, Asaba, Nigeria; A. D. O. and A. A. O.: Department of Animal Science, University of Ibadan, Ibadan, Nigeria)

A 56-day experiment was conducted to determine thereplacement value of maggot meal for fish meal in diet of laying chicken. Fish meal was included at 30 g kg-1 of the control diet. Maggot meal incrementally replaced fish meal at 250, 500, 750, and 1000 g kg-1 on crude protein basis. The five diets were fed to a total of 120 36-week- old Nera breed-laying chickens. Inclusion of various amounts of maggot meal in laying chicken diets had no significant impact on daily feed intake, hen-day egg production, egg weight, feed efficiency, and liveability. Aspects of egg external and internal quality characteristics measured were identical (P>0.05); however, albumen weight (as percent of egg weight) was significantly (P<0.05) high in birds fed with diet which contained equiprotein inclusion of both fish and maggot meal. Egg yolk cholesterol and calcium concentration were significantly reduced (P<0.05) with increased inclusion of maggot meal in laying chickens' diet. The use of maggot meal in poultry rations may reduce cholesterol intake through consumption of eggs. It is concluded that maggot meal can nutritionally and productively replace fish meal in layer diet without adverse consequences on performance and egg quality characteristics.

Original scientific paper. Received 10 Jan 98; revised 2 Aug 98.

SHALLOT ROOT DISTRIBUTION AND BULB YIELD AS INFLUENCED BY IRRIGATION FREQUENCY

Department of Horticulture, Wye College, University of London, Wye Ashford, Kent TN25 5AH, UK (L. A.'s present address: Crops Research Institute, CSIR, P. O. Box 3785, Kumasi, Ghana)

The effect of irrigation frequency on lateral and vertical root growth, and bulb yield of shallots (Allium cepa var. ascalonicum cv. Tropix) was investigated in the field (polytunnel). The experimental treatments were dry (85 l of water; frequency = 12), medium (135 l of water; frequency = 20), and wet (220 l of water; frequency = 36). The wet treatment recorded the highest lateral root growth. Vertical root growth (root depth) was unaffected by irrigation frequency to any significant extent. Number of bulbs per plant was the same in all the three irrigation treatments. The wet- treated shallots had the highest bulb diameter, bulb weight, and bulb yield.

Original scientific paper. Received 9 Aug 96; revised 4 Aug 98.

EFFECT OF RAINFALL VARIABILITY ON GRASSLAND HERBAGE PRODUCTION AND RUMINANT LIVESTOCK PRODUCTIVITY IN THE ACCRA PLAINS OF GHANA

(J.E.F.: Department of Animal Science, University of Ghana, P.O. Box 226, Legon, Ghana; S.A-M.: Department of Agricultural Engineering, University of Ghana, P.O. Box 28, Legon, Ghana)

Even though rainfall amount influences herbage production, there is a wide range outside which there can be depression of forage dry matter yield on the Accra plains. Low rainfall amount does not seem to depress livestock numbers but may affect the performance of individual animals. However, very heavy rainfall may affect the animals in various ways leading to an eventual reduction in their numbers.

Original scientific paper. Received 4 Aug 97; revised 21 Aug 98.

STUDIES ON PERFORMANCE OF SOME OPEN-POLLINATED MAIZE CULTIVARS IN THE GUINEA SAVANNA. II. GENETIC CONTRIBUTION TO PRODUCTIVITY OF FOUR CULTIVARS UNDER VARYING POPULATION AND NITROGEN REGIMES

Crops Research Institute, CSIR, P. O. Box 3785, Kumasi, Ghana

Three late-maturing varieties of maize (Zea mays L.) released from 1972 to 1988 and one local cultivar were evaluated in replicated field trials at Nyankpala and Damongo in 1992 and 1993. Plant densities (30 000, 50 000, 70 000 plants ha-1) were assigned to the main-plots and 12 combinations of N fertilizer levels (0, 80, 160 kg N ha-1) and varieties (Local, Composite 4, Dobidi, Okomasa) were assigned to the sub-plots in four replicates. The objective was to determine the rate of increase in grain yield due to genetic improvement under the different levels of soil fertility and plant densities. Across location

analysis for grain yield showed significant (P<0.05) differences among plant densities and highly significant (P<0.01) differences among nitrogen levels and varieties. The density x nitrogen and nitrogen x variety interactions were also significant. The overall variety mean grain yields were 3.08, 4.44, 4.48 and 4.60 t ha-1 for the local variety, Composite 4, Dobidi and Okomasa, respectively. Linear regression estimates of grain yield increases (yield gains) per year were 32.3 kg ha-1 at zero-N, 45.1 kg ha-1 at 80 kg N ha-1, and 56.4 kg ha-1 at 160 kg N ha-1. Linear estimates over the three N levels were significant and positive for grain yield, days to 50 per cent silk emergence, percent grain moisture content at harvest, and 1000-seed weight, but was negative for ear acceptability rating and percent total lodging. One thousand seed weight, stover weight and ears per plant had significant positive correlations with grain yield whereas ear rating and total lodging were negatively correlated with yield. The data showed that (i) significant progress has been made in genetic improvement of maize in Ghana since breeding programmes were initiated in the mid-1950s, (ii) breeding was effective in improving yield potential of maize under low as well as at high levels of soil fertility, (iii) increase in yield potential of the varieties resulted in corresponding increases in size and uniformity of ears, 1000-seed weight and tolerance to lodging, and (iv) increase in yield potential did not result in proportionate yield increases in farmers' fields.

Original scientific paper. Received 11 Jun 97; revised 27 Aug 98.

EFFECTIVE MANAGEMENT OF PIGEON PEA (CAJANUS CAJAN) IN A CROP/LIVESTOCK INTEGRATED FARMING SYSTEM IN NORTHERN GHANA

(N. K. & J. B.: Animal Research Institute, CSIR, P.O. Box 52, Nyankpala, Tamale, Ghana; A. L. N.: Savanna Agricultural Research Institute, CSIR, P.O. Box 52, Nyankpala, Tamale, Ghana; F. K. F.: Department of Animal Science, Faculty of Agriculture, University of Ghana, Legon, Ghana)

Efficient management of pigeon pea, Cajanus cajan var. Katinga, as a resource in crop/livestock integration in northern Ghana was studied. Pigeon pea plots with row lengths averaging 11 m and a planting geometry of 80 cm W 50 cm, were either pruned at 60 or 100 cm above ground level or not pruned. Pruning was done at 11 or 16 weeks after planting. Early pruning at a height of 60 cm above ground gave significantly higher (P<0.05) seed, pod, and husk yields. Feeding experiments were conducted to compare pigeon pea hay to urea treated rice straw as supplementary feed for Djallonke castrates. Diet 1 (Cajanus-N) consisted of pigeon pea hay, cassava peels, and untreated straw while Diet 2 (Urea-N) consisted of 4 per cent urea-treated straw and cassava peels. Total daily supplementary feed dry matter (DM) intake was 365 and 300 g/head for Diet 1 and Diet 2, respectively. DM digestibility was similar in both groups of animals (67.1 - 67.8 per cent). Weight gain was the same for both treatments but Cajanus-N enhanced lean tissue deposition.

Original scientific paper. Received 3 Sep 96; revised 3 Sep 98.

BENEFICIAL EFFECTS OF BENDING MAIZE PLANTS AT PHYSIOLOGICAL MATURITY ON LODGING AND ON SOME PRE-HARVEST GRAIN QUALITY PARAMETERS

Department of Crop Science, Crop Protection Section, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana

In the study, maize plants (cv. Aburotia) bent, just below the lowest ear, at 2 weeks before physiological maturity (PM), at PM, and 2 weeks after PM were compared with unbent plants for grain moisture content, cob infestation with insects (adults and larvae), grain mouldiness, grain yield per cob, and incidence of lodging. The bending and no bending treatments were applied in a randomized complete block design with three replications. Relevant weather records during the study period were provided by the Kumasi Meteorological Station. Grain moisture content, cob infestation with adult insects, and extent of lodging were, at harvest, significantly lower (P=0.05) in bent plants than in unbent ones. Among the bent plants, these parameters decreased with early bending. Moisture content of grains from plants bent 2 weeks before PM, at PM, and 2 weeks after PM, for example, were, at harvest, 23.3, 25.3, and 31.7 per cent, respectively, compared to 38.3 per cent recorded for unbent plants. Similarly, while only 1 - 2 plants/m2 lodged on plots with bent plants, an average of 5 plants/m2 lodged on plots with unbent plants. Cob infestation with stemborers/earworms, incidence of mouldiness, and grain damage per cob, also, were lower in bent than in unbent plants. Dry weight of marketable grains per cob was significantly highest (79.85 g/cob) in plants bent at PM and lowest (71.35 g/cob) in plants bent 2 weeks earlier. These results indicate that the bending over of maize plants has crop protection value. They further show that the ideal developmental stage to bend plants to combine the benefits of reduced pre-harvest grain moisture contents and field losses with maximum grain yield is at PM.

Original scientific paper. Received 4 Nov 97; revised 21 Sep 98.

INFLUENCE OF SETT SIZE AND SPACING ON YIELD AND MULTIPLICATION RATIO OF GINGER (ZINGIBER OFFICINALE ROSC.)

Department of Crop Science, University of Ghana, P. O. Box 44, Legon, Ghana

Four sett sizes (1, 2, 5, and 10 g) of ginger (Zingiber officinale Rosc.) and three spacings 12 cm W12 cm, 15 cm W 15 cm, and 15 cm W 23 cm) were studied for their effect on sprouting, vegetative growth, yield, and multiplication ratio. Percent sprouting in moist sawdust under greenhouse conditions was highest for the 10 g sett class and decreased with reduction in sett size. The largest and the smallest sett sizes had 100 and 75 per cent sprouting, respectively. There was a direct relationship between sett size planted and both vegetative growth and rhizome yield. The contrary was observed in sett size to rhizome

ratio (multiplication ratio). The smallest sett size yielded a multiplication ratio of 9.85 compared to 4.78 for the largest sett size. Of the three spacing regimens investigated, the wider spacings produced higher vegetative growth as well as rhizome yield per plant. However, rhizome yield/ha was adversely affected by wider spacing. The highest yield of 29.69 t/ha was produced from the largest sett size (10 g) planted at the closest spacing of 12 cm W 12 cm. The combination of smallest sett size and widest spacing produced the lowest rhizome yield of 3.37 t/ha.

Original scientific paper. Received 4 Feb 98; revised 23 Sep 98.

THE INFLUENCE OF TYPE OF PALM KERNEL CAKE ON THE GROWTH RATE AND CARCASS CHARACTERISTICS OF PIGS

Animal Research Institute, CSIR, P. O. Box 20, Achimota, Ghana

Forty-eight large white pigs at an average initial liveweight of 20 kg were distributed over three treatments made up of a control diet and two diets containing palm kernel cake from two oilmills, incorporated into the diets at 300 g/kg level. The average daily gains of the pigs were 0.57, 0.46, and 0.49 kg/day on control, Oilmill A (PKC A), and Oilmill B (PKC B) diets during the grower period. Corresponding values were 0.60, 0.63, and 0.65 kg/day during the finisher period, and 0.60, 0.54, and 0.55 kg/day during the entire grower-finisher period. Feed conversion efficiency (kg/kg liveweight gain) with the pigs on the diets were 3.44, 3.87, and 3.94 (grower period), 4.53, 5.63, and 4.91 (finisher period), and 4.0, 4.77, and 4.41 (grower-finisher period). There were significant differences (P < 0.05) in the carcass length, eye muscle area, and the hand joint of the pigs. Other measures of carcass characteristics were not significantly (P > 0.05) different. There was the indication, however, of non-significant differences in the carcass characteristics due to the type of the palm kernel cake. The study has shown that palm kernel cake with high level of residual fat induced higher average daily gain, better feed conversion efficiency, increased carcass fatness with reduced leaness in pigs.

Original scientific paper. Received 27 Aug 96; revised 29 Sep 98.

EFFECTS OF STRIGA HERMONTHICA INFESTATION ON IMPROVED MAIZE CULTIVARS IN GHANA

(P. Y. K. S.: Crops Research Institute, CSIR, P. O. Box 3785, Kumasi, Ghana; D. A.: Savanna Agricultural Research Institute, CSIR, P.O. Box 52, Tamale, Ghana)

Four improved composite varieties of maize (Zea mays L.) grown by farmers in the savanna zones of Ghana and one striga-tolerant single-cross hybrid were screened under two levels of striga infestation in replicated field trials at Nyankpala in 1993 and 1994 to determine the effects and severity of striga infection on the varieties. Effects due to striga infestation and varieties were significant (P< 0.05) for grain yield and some plant and ear traits. The striga infestation level W variety interaction was not significant for any of the traits. Striga infestation reduced plant height by 18.8 per cent, increased lodging by 136.9 per cent, but had no significant effect on the number of leaves per plant in the varieties. Ears per plant, ear weight, grain weight, ear acceptability, and grain yield declined by 22.9, 50.0, 16.5, 24.0, and 66.0 per cent, respectively, in the varieties in response to striga infestation. The results showed that (i) striga infestation had profound detrimental effects on growth and productivity of all the maize varieties, (ii) these effects were less severe in the striga-tolerant hybrid than in the composites, and (iii) breeding to improve cultivar tolerance to striga needs emphasis.

Original scientific paper. Received 21 Oct 97; revised 2 Oct 98.

CHARACTERIZATION OF PERI-URBAN DAIRY PRODUCTION IN GHANA. 2. HEALTH AND OTHER CONSTRAINTS IN THE PRODUCTION SYSTEM

S. A. OKANTAH, E. O. K. ODDOYE, F. Y. OBESE, P. GYAWU & Y. ASANTE

S. A.O., E.O.K.O., F.Y.O.: Animal Research Institute, CSIR, P.O. Box 20, Achimota, Ghana; P.G.: Department of Animal Science, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana; Y. A.: Department of Economics, University of Ghana, Legon, Ghana)

A survey was carried out in five districts of the Accra plains to characterize the peri-urban dairy system. Results of the survey indicated that farmers were not treating their animals with anthelmintic. The use of acaricide and the control of trypanosomiasis was fairly frequent. Skin diseases, ticks, digestive diseases, and trypanosomiasis were the most important diseases affecting farmers' cattle in that order. The lack of livestock extension and the unwillingness of banks to provide credit facilities for cattle farming were identified as other factors hampering the growth of the dairy industry in Ghana.

Original scientific paper. Received 10 Jun 96; revised 27 Oct 98.

MAIZE QUALITY REQUIREMENTS OF PRODUCERS OF SIX TRADITIONAL GHANAIAN MAIZE PRODUCTS

Food Research Institute, CSIR, P. O.Box M. 20, Accra,Ghana

Eight commercial producers of aboloo, Fanti kenkey, fomfom, Ga kenkey, nsewhu and workple from 18 towns of six southern regions of Ghana were interviewed on the quality of maize required by them for making their products. In decreasing order of importance, respondents chose general appearance, insect damage, moisture content, foreign matter, and mouldiness as the main quality indices they would like to be used as criteria for grading maize. The type of maize product influenced the choice of quality requirements for maize. Producers of workple, a wholemeal unfermented maize product, preferred maize of no mouldiness, almost no insect damage, and low moisture content. For aboloo, Fanti and Ga kenkey producers, maize of low moisture content, low insect damage, good general appearance and no mouldiness was equally important. Producers of nsewhu and fomfom, two dehulled fermented maize products, require maize which can easily be dulled. Most producers have problems using most of the newly released varieties of maize.

Original scientific paper. Received 24 Feb 98; revised 3 Nov 98.

BASELINE SURVEY OF TIGER NUT (CYPERUS ESCULENTUS) PRODUCTION IN THE KWAHU SOUTH DISTRICT OF GHANA

School of Agriculture, University of Cape Coast, Cape Coast, Ghana

Tiger nut (Cyperus esculentus) is a minor but important crop in Ghana. In a survey conducted on the production and marketing of the crop at Aduamoa in the Kwahu South District of Ghana, it was observed that tiger nut production was predominantly the work of women, with 70 per cent of farmers being women and 30 per cent men. Most men farmers were younger, with 73 per cent of them within age group 15-40 years. The women farmers were older, with 70 per cent of them within the age group 41-65 years. Farm sizes were small, ranging from 576 to 4200 m2. Two distinct types of tiger nuts, the Kwahu type with yellowing brown nuts and the Fanti type with a mixture of dark brown and black nuts, are cultivated in the area. Consumer preference for the Kwahu type is higher. The crop is grown on mounds, and it may be intercropped with maize, cassava, or cocoyam. Yields range between 2.3 and 11.3 t/ha. Harvested nuts may be dried with or without washing, and stored up to 6 - 12 months in aerated containers. Themajor constraints to production include high labour cost for land preparation and harvesting. However, the crop has a high export potential.

Original scientific paper. Received 12 Sep 96; revised 7 Dec 98.

GROWTH RATE AND CARCASS CHARACTERISTICS OF INDIGENOUS (ASHANTI DWARF) PIG

Department of Animal Science, University of Ghana, Legon, Ghana

Fourteen Ashanti Dwarf pigs were grouped according to sex and raised intensively after weaning. Each pig received feed equivalent of 5 per cent live weight daily. The feed contained about 18.4 per cent crude protein and 13.2 MJ (ME) per kilogram diet. The animals were weighed monthly. All the seven boars were castrated at 5 months of age. The growth rate of the males was higher than the females in the first 4 months. The females overtook the males in growth rate from the 5th month until they were slaughtered at the age of 10 months. Mean slaughter weight of females (60.5 kg) was significantly higher (P<0.05) than the castrates (53.6 kg). Dressing percentage of castrates (79.1 per cent) was similar to that of the females (80.5 per cent). The percentage fat trimmed and carcass length of the females were significantly (P<0.05) higher than those of the castrates. Primal cuts, 4 per cent lean cuts, back fat thickness, and Longissimus dorsi area were similar (P>0.05) for both sexes.

Original scientific paper. Received 12 Sep 97; revised 14 Dec 98.

RELIABILITY OF SOME SIMPLE METHODS FOR ASSESSING THE IMMUNOGLOBULIN STATUS OF NEW-BORN CALVES

K.T. DJANG-FORDJOUR, C. CAMERON, G. FISHWICK & R. G. HEMINGWAY

(K.T.D.-F: Department of Animal Science, University for Development Studies, Tamale, Ghana; C.C., G. F. & R. G. H.: Department of Veterinary Clinical Studies, Glasgow University Veterinary School, Bearsden, Glasgow, Scotland)

Blood sera with a wide range of immunoglobulin concentrations were obtained from closely managed beef calves by sampling pre-suckling, at 2 days, and at some intermediate times. Immune globulin status was determined by a zinc sulphate turbidity test, by refractometer, and by the coagulation times with a glutaraldehyde solution. Values for all three tests correlated very significantly (P<0.001) with globulin concentrations obtained with a Technicon Autoanalyser, and can be used with confidence for rapid and satisfactory results where elaborate laboratory facilities are unavailable.

Original scientific paper. Received 21 Jan 98; revised 22 Dec 98.

THE ROLE OF GENETIC DIVERSITY IN SUSTAINABLE AGRICULTURE

Crops Research Institute, CSIR, P. O. Box 3785, Kumasi, Ghana

The depletion of plant biodiversity with the rapid development of agriculture has attracted growing interest in recent years. This paper discusses the evolutionary consequences of monoculture with emphasis on the buffering effects of genetic heterogeneity on disease. The use of host plant resistance and systemic fungicides as disease control measures and their influence on sustainable agriculture are discussed. Three approaches of re-introducing genetic diversity into modern agriculture are indicated. These are composite crosses, multiline varieties, and variety mixtures. It is concluded that the variety

mixtures approach holds promise for developing countries where low input cropping systems are practised.

Subject review article. Received 26 Aug 97; revised 30 Nov 98.