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Overcoming the constraints of dry matter intake on dual-purpose goat production by feeding defoliated maize leaves

P.P. Semenye, M. Shisya and W.R. Getz

SR-CRSP/Winrock International
P.O. Box 252, Maseno, Kenya


Abstract
Introduction
Materials and methods
Results and discussion
Conclusion
References


Abstract

Feeding trials were conducted at Maseno, Kenya, based on defoliated maize leaves from three plots measuring 0.25 ha each. On average, each plot produced 359 kg (SE 40 kg) dry matter of defoliated leaves as forage. Defoliation, which commenced at the tasselling stage at the rate of one leaf per week per maize plant, did not affect the grain yield. The defoliated maize leaf forage had 12% crude protein and in vivo dry matter digestibility of 60%.

In maize-growing areas where there are no pastures or land for growing fodder, it is recommended that feeding and management of goats should be strategically matched with maize production. Lactation period should coincide with the availability of maize leaves, while yearlings should take full advantage of a maize leaf diet which gives better performance than a grass mixture diet.

Utilisation de feuilles de mais dans l'alimentation de chèvres aptitudes mixtes afin de supprimer les facteurs limitant la consommation de matière sèche

Résumé

Des essais d'alimentation ont été conduits à Maseno (Kenya) avec des feuilles de plants de mais provenant de trois parcelles de 0,25 ha. Chaque parcelle produisait en moyenne 359 kg (+40 kg) de matière sèche sous forme de feuilles utilisées comme fourrage. La défoliation des plants de mais, commencée au stade de la formation des aigrettes à raison d'une feuille par semaine et par plant, n'a pas eu d'effet sur le rendement en grains. Les feuilles de mais servant de fourrage présentaient une teneur en protéines brutes de 12% et une digestibilité in vivo de la matière sèche de 60%.

Dans les régions productrices de mais où l'on manque de pâturages et de terres se prêtant à la production de fourrages, il est recommandé d'aligner stratégiquement l'alimentation et la conduite des caprins sur la production de mais et de synchroniser la période de lactation et l'époque où les feuilles de mais sont disponibles. Par ailleurs, les chevreaux de 1 an devraient pouvoir bénéficier d'un régime à base de feuilles de mais, ce type de ration permettant des performances supérieures à celles obtenues avec un régime à base d'un mélange d'herbe

Introduction

Kenya's population is expected to increase by more than 50% by the end of the century. This forecast has serious implications for livestock production in densely populated areas with small farms as is the case in western Kenya. In these areas human and livestock populations are inversely correlated. As the human population increases, more land is needed for food crop production. This is acquired from livestock's share of land resources. As land previously reserved for livestock is taken, stocking pressure increases. This results in logistical destocking and poor performance syndrome caused primarily by low intake of dry matter. A sustainable solution to this problem could be the integration of livestock with crop production. For this reason research for dual-purpose goats (DPG) in western Kenya focuses on integration of the sub-systems.

Materials and methods

Three plots of a quarter hectare each were demarcated from a plot of two hectares planted with maize hybrid seed no. 621. The number of maize plants at knee height on each plot was counted. Plot 1 had 7875 maize plants, Plot 2 had 7536 and Plot 3 had 9278, giving a total of 24,689 and an average of 8230 plants per plot. Randomly, Plot 1 was allocated to two lactating does, Plot 3 to three yearlings and Plot 2 was the control. Defoliation began 79 days after planting. Grain yield was determined by harvesting every fifth maize plant on a transect running longitudinally on each plot. Nine yearlings and two does were used, all crossbreeds (F1) of Toggenburg with East African Goat. The yearlings, with an average live weight of 21.2 kg ( ± 0.2 kg), were allocated randomly in groups of three to three feeding treatments of grass mixture, maize leaves and concentrates (dairy meal). Their adaptation period to the feeding trial was determined by the yearlings' live weight trend. The adaptation period was five weeks, which was the time the yearlings took to regain their initial live weight, following a weight loss on introduction to the experiment. The experimental period was determined by the availability of green maize leaves and lasted eight weeks. Yearlings and does were treated against helminthiasis before the experiment started. All the goats were placed in metabolic cages to determine dry matter intake (DMI) and in vivo dry matter digestibility (IVDMD). The animals were fed three times a day at 0900 h, 1300 h and 1600 h.

Table 1. Maize grain and defoliated leaves production per quarter hectare.

Parameter

Plot 1 (Does)

Plot 2 (Control)

Plot 3 (Yearlings)

Overall mean

SD

Number of plants

7875

7536

9278

8230

924

Number of leaves

110250

105504

129892

115215

12930

Leaf dry matter (kg)

344

329

405

359

40

Grain yield (kg)

1362

1263

1387

1337

66

Grain yield/plant (g)

173

168

149

163

13

SD = standard deviation

Kjeldahl, and Tilley and Terry (1963) chemical analyses were conducted. Energy calculations were based on coefficients and formulas of MAFF (1975) and NRC (1981). SYSTAT (Wilkinson, 1990) was used for data analysis.

Results and discussion

The grain yield was affected by plant population, but not by defoliation (Table 1). Plot 3 had the highest population and the highest total grain yield, but the grain yield per plant was the lowest. The mean grain yield of 5349 kg per hectare or 59 bags of 90 kg each is above the western Kenya average of 29 bags/ha (Ministry of Agriculture, 1987). Stripping the maize leaves allows for easy under sowing in the maize fields. Similar results from maize defoliation have been reported elsewhere. During defoliation there were more green leaves available than the goats could eat. Plot 1, which catered for two does, produced 344 kg dry matter of green maize forage, while the total dry matter intake (DMI) over the trial period of 90 days was 333 kg. Plot 3 produced 405 kg dry matter, while the total DMI of the three yearlings was 213 kg. The yearlings' plot produced sufficient forage either to cater for two more yearlings over the same duration, or to extend the three yearlings' feeding duration from 90 to 171 days.

Stripping maize leaves was an easier task than cutting mixed grass because, unlike cutting grass mixture, it is a focused activity and requires no implements.

Table 2 shows that the crude protein (CP) content of maize leaves was above the threshold known to limit DMI. Maize leaves had better in vitro dry matter digestibility (DMD) than grass leaves. As expected the concentrate diet had a higher CP content and DMD than maize leaves and grass mixture.

There was an inverse correlation between the age of the maize and the quality of the defoliated leaves. CP dropped from 14 to 10% (r =-0.91) while DMD dropped from 66 to 56% (r =-0.74). Concentrate quality remained constant, while variations in the grass mixture were kept minimal by selective cutting.

The success of fodder production is ultimately judged by livestock response. Table 3 shows that yearlings responded positively to a diet of maize leaf. Kayongo-Male and Abate (1982) reported growth responses of 95 and 98 g/day for sheep fed on maize leaves, higher than that found in this study. Sheep performance was better than that achieved by goats with concentrates. The difference between the species was probably due to ease of adaptation to a new feed rather than conversion efficiency. Sheep are more adaptable to a new feed than goats.

Table 2. Chemical composition of the diets (%).

Parameter

Grass mixture

Maize leaves

Concentrate

Mean ± SD

Mean ± SD

Mean ± SD

Dry matter

31a

3.2

34a

3.6

94b

0.9

Crude protein

12a

0.8

12a

0.8

18b

1.0

In vitro DMD

57a

2.1

64b

1.8

78c

1.9

In vivo DMD

61a

6.4

60a

4.5

68b

2.9

abc = means in the same row having different superscripts differ significantly (P<0.05)
SD = standard deviation.

Bulkiness is known to fill the gut resulting in lowered dry matter and energy intake. Contrary to this known phenomenon, yearlings fed the grass mixture and maize leaves diets (Table 3) consumed more dry matter on body weight basis (3.5%) than yearlings fed the concentrate diet (3.1%). Notwithstanding their relatively lower intake of dry matter, yearlings fed the concentrate diet utilized their feed more efficiently and grew better than yearlings fed the grass mixture and maize leaves diets. The yearlings on the grass mixture were the least efficient in feed utilization and growth. The lower protein: energy ratios of the grass mixture and maize leaves diets may have been largely responsible for the lower response of yearlings fed these diets.

Table 3. Performance of DPG yearlings fed grass mixture, defoliated maize leaves and concentrates.

Parameter

Grass mixture

Maize leaves

Concentrates

As-fed (kg/day)

3.0

3.5

1.5

DMI (g/day)

764

788

723

DMI (% body wt.)

3.5

3.5

3.1

Average daily gain (g/day)

27

45

89

Protein: energy ratio

8

8

12

Feed conversion

28

18

8

The two lactating does in the trial were in their third and sixth months of lactation. They were previously on a high plane of nutrition made up of a grass mixture as the basal diet, and Leucaena leucocephala and concentrates as supplementary feeds. For the nine months' lactation on a high plane of nutrition, the does produced an average milk yield of 1.7 kg per day/doe. When the does switched to defoliated maize leaves, the average milk yield dropped to 0.9 kg per day/doe for a six months' lactation. The drop in yield was partially due to the normal decline in milk production with advancing lactation, but also due to the insufficiency of maize leaves for sustaining milk production. The average DMI for maize leaves was 1.3 + 0.3 kg per day/doe. Based on an in vivo DMD of 62%, this supplied 10.9 MJ (ME)/day per doe. This energy supply fell short of the daily energy requirement of a doe by 1.3 MJ ME. An attempt by the does to meet this energy deficit may have resulted in the observed average loss of 3.75 kg or 9% of body weight/doe during the 90 days' lactation period. Maize leaves can promote milk production, but in order to minimise mobilisation of body reserves, keeping the does' milk production at 0.7 kg/day is recommended.

For western Kenya and other areas with two maize seasons per year, DPG production can be integrated with maize production for the latter to provide forage (Table 4). Except for the 0.1 ha plot size, defoliated maize leaves' potential production is in excess of a year's demand for a 40 kg doe producing 0.7 kg milk per day. Excess forage can therefore be stored, used for raising more DPGs or both. The nutritive value of defoliated leaves is high for three months per season. With two growing seasons there are six months of high quality forage per year. Excess leaves could be sold and the proceeds used to purchase farm inputs or to meet personal needs.

Conclusion

Kenyans grow maize year in year out because it is a preferred food crop. As long as maize maintains this role, its production must be capitalised on for the enhancement of sustainable agriculture. The importance of integrating maize production with other crops and livestock production cannot be over emphasised. Also the benefits derived from under sowing in defoliated maize plots need to be assessed. An under sown crop in a plot of defoliated maize plants has more access to sunlight, and hence the opportunity for higher photosynthetic output.

Table 4. Production of defoliated maize leaves per plot size and DPG feeding days.

Maize plot size (ha)

Defoliated leaves production potential (number)

Dry matter yield

Potential feeding days for a 40 kg doe producing 0.7 kg milk per day

per season

per year

1.0

460860

1437

1105

2210

0.5

230430

719

553

1106

0.25

11525

359

276

552

0.1

46086

144

111

222

References

Haenlein G F W. 1978. Dairy goats do well on free choice feeding. Hoard's Dairyman 123:1194.

Kayongo-Male and Abate. 1982

MAFF (Ministry of Agriculture, Fisheries and Food). 1975. Energy allowances and feeding systems for ruminants. Technical Bulletin 33. Her Majesty's Stationery Office, London, UK. 79 pp.

Ministry of Agriculture, Kenya Government. 1987. Per hectare gross margins. Nairobi, Kenya.

NRC (National Research Council). 1981. Nutrient requirements of goats: Angora, dairy and meat goats in temperate and tropical countries. Nutrient

Requirements of Domestic Animals Number 15. National Academy of Sciences, Washington DC, USA. 91 pp.

Tilley J M A and R A Terry. 1963. A two stage technique for in vitro digestion of forage crop. Journal of the British Grasslands Society 18:104.

Wilkinson L. 1990. SYSTAT. The System for Statistics. SYSTAT, Inc. Evanston IL, USA..


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