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Performance of weaner lambs fed maize leaves and napier grass

A.N. Abate1 and A. Abate2

1Kenya Agricultural Research Institute, P.O. Box 57811, Nairobi, Kenya
2Department of Animal Production, University of Nairobi P.O. Box 29053, Nairobi, Kenya


Abstract
Introduction
Materials and methods
Results
Discussion and conclusion
References


Abstract

Maize leaves were compared to napier grass in experiments designed to measure their nutritive value and their effect on the growth of weaner lambs under stall feeding conditions. In the first trial, one leaf per plant per week was systematically plucked about three months post-emergence; in the second, green leaves were defoliated from the bottom of the plant about 4-5 months after germination. In both cases, animals fed the maize leaves gained significantly more weight (P<0.01) than those fed napier grass. The effect of leaf defoliation on forage dry matter (DM) productivity and grain yield is discussed.

Performances des agneaux sevrés nourris avec des feuilles de mais et de l'herbe à éléphant

Résume

Deux expériences ont été mises en place pour mesurer la valeur nutritive des feuilles de mais et de l'herbe à éléphant et comparer leurs effets sur la croissance d'agneaux sevrés alimentés en bergerie. Dans le premier essai, une feuille par plante était cueillie toutes les semaines trois mois environ après la levée; dans le second essai, les feuilles vertes du bas de la plante ont été cueillies 4 à 5 mois après la germination. Dans les deux cas, la croissance pondérais des animaux nourris avec les feuilles de mais était supérieure (P<O,OI) à celles des animaux nourris avec l'herbe à éléphant. L'effet de la défoliation sur le rendement en matière sèche fourragère et en grains de mais est examiné.

Introduction

Grazing lands in the agriculturally rich highlands and coastal subhumid zones of sub-Saharan Africa are diminishing, mainly due to the increase of human settlements. This is increasingly causing a scarcity of fodder for small ruminants.

In Kenya napier grass has been identified as being productive, persistent and easy to harvest (Mwakha, 1972; Boonman, 1977; Karanja, 1984). It is also palatable and gives reasonable growth rates and milk yields in cattle (Abate et al, 1992). However, under smallholder conditions, the growing of pure fodder may be limited by the farmer's need to meet his own food requirements. Defoliated maize leaves for fodder have been integrated into crop and animal production trials with satisfactory results (Abate 1981, 1982, 1983). A study was undertaken to record the effects of maize leaf and napier grass diets on Corriedale sheep. This paper reports the findings.

Materials and methods

Weaner lambs of the Corriedale breed were allocated to two groups of four. The lambs were approximately five months old and had an average weight of 21 kg. They were dewormed prior to the experiment. One group was the treatment group and received maize leaves ad libitum. The control group was offered napier grass ad libitum. The trial lasted for 10 weeks. Maize leaves were defoliated from a plot of hybrid maize plants about three months post-emergence at a frequency of one leaf per plant per week. A second plot remained undefoliated as a control. Both the maize leaves and napier grass were chopped before being fed to the animals. Group dry matter (DM) intake was recorded daily and each sheep was weighed once a week. Clean water and mineral licks were freely available. Feeds offered and refusals were sampled weekly, dried in a draught oven and milled through a 2 mm sieve for laboratory analysis.

In an experiment carried out the following year, the digestibility of maize leaves defoliated about 4-5 months after germination was compared to that of napier grass. Maize leaves were obtained by picking green leaves from the bottom of the plant upwards, leaving only the four nearest the cob. The maize leaves and napier grass were chopped before being fed ad libitum to the animals. The wethers were fed for a preliminary period of approximately three weeks, then there was a collection period of seven days. Composite samples collected over the seven days were oven-dried at 60°C and ground for analyses. Individual animal weights were recorded at the beginning and end of the trial. Data from both experiments were subjected to statistical analysis.

Results

Results of the performance trial are given in Tables 1 and 2 and in Figure 1. The maize leaves were similar in DM content to the napier grass but higher in crude protein (CP) levels (Table 1). The concentration of CP in both forages declined with age (Figure 1) at the rate of 1.1% and 0.4% per week for defoliated maize leaves and napier grass respectively. Defoliated maize leaves gave a higher DM intake and a daily gain in weight that was roughly three times higher than napier grass. Efficiency of feed conversion was more than two times higher in the lambs fed maize leaves than in those fed napier grass. Maize defoliation produced approximately 1.5 tonnes of leaf DM per hectare without significantly (P>0.05) reducing grain yield (4.90 vs 5.31 tons/hectare).

Table 1. Chemical composition and effect on weaner lamb performance of defoliated maize leaves and napier grass.

 

Defoliated maize leaves

Napier grass

Dry matter, %

22.4

21.3

Crude protein, %

16.6

8.6

Dry matter intake (g/day)

887.0

683.0

Average daily gain (g/day)

136.0a

48.0b

Feed conversion efficiency

6.5

14.1

ab = Values in a row bearing different superscripts are significantly different (P<0.05).

Figure 1. Changes in crude protein content of defoliated maize leaves and napier grass.

Table 2 shows the results of the digestibility experiment. Both defoliated maize leaves and napier grass were similar in chemical characteristics, although the latter had more fibre. DM digestibility was also similar. However, intake of DM was significantly (P<0.001) higher in maize leaves than in napier grass. All wethers fed on maize leaves gained weight while those fed napier grass lost weight; the differences in weight changes were significant (P<0.05).

Table 2. Nutritional characteristics of defoliated maize leaves and napier grass when fed to wethers.

 

Defoliated maize leaves

Napier grass

Dry matter, %

34.5

33.9

Crude protein, %

9.6

8.2

Neutral detergent fibre, %

66.7

73.0

Dry matter digestibility, %

54.6

56.1

Dry matter intake (g/day)

1161.0a

662.0b

Average daily gain, g

+67.0a

-43.0b

ab = Values along a row bearing different letters are significantly different (P<0.001) or (P<0.05).

Discussion and conclusion

The results of this experiment have shown that defoliated maize leaves can be a source of quality feed for ruminants. The leaves proved to be more acceptable and of higher nutritional value than napier grass. This is significant because for a given weight of DM more meat can be produced from animals fed maize leaves than from those fed napier grass. Earlier, Kayongo-Male and Abate (1982) had shown that fresh maize leaves were nutritionally superior to hay. Stripping one leaf per plant per week spread the use of the leaves over a period of 10 weeks although at the cost of quality. Plucking more leaves per plant per week produces better quality feed but for a shorter duration (Abate, 1983). The effect of defoliation on grain yield is important as maize forms the staple diet of most countries in East Africa. A reduction in grain yield of about 8% is considered small and the liveweight gain would compensate for the loss. Lower reductions in grain yield of 2.6% have been reported before (Abate, 1981).

References

Abate A N. 1981. Performance of weaner lambs fed on systematically defoliated maize leaves. Annual Report, Animal Production Research Department, KARI (Kenya Agricultural Research Institute), Muguga, Kenya.

Abate A N. 1982. Performance of Corriedale lambs fed on maize leaves defoliated at different stages of growth and at different frequencies. Annual Report, Animal Production Research Department, KARI (Kenya Agricultural Research Institute), Muguga, Kenya.

Abate A N.1983. Voluntary dry matter intake and digestibility of maize leaves and napier grass by young wethers. Annual Report, Animal Production Research Department, KARI (Kenya Agricultural Research Institute), Muguga, Kenya.

Abate A, Dzowela B H and Kategile J A. 1992. Intensive animal feeding practices for optimum feed utilisation. In: Kategile J A and Mubi S (eds), Future of livestock industries in East and southern Africa. Proceedings of a workshop held at Kadoma Ranch Hotel, Zimbabwe, 20-23 July 1992. ILCA (International Livestock Centre for Africa), Addis Ababa, Ethiopia. pp. 9-19.

Boonman J G. 1977. Fodder farming in East Africa. A preliminary report on the status of the development of tropical pastures in East Africa (Part 11). Ministry of Agriculture, Nairobi, Kenya.

Karanja G M. 1984. The effects of frequency and height of cutting on tillering, herbage yield and nutritive value of four varieties of napier grass. MSc thesis, University of Nairobi, Nairobi, Kenya.

Kayongo-Male H and Abate A N. 1982. Role of systematic maize (corn) defoliation in small ruminant production. In: Proceedings of the small ruminant-CRSP Workshop, March 15th, 1982, Nairobi, Kenya. pp. 145-150

Mwakha E. 1972. Effect of cutting frequency on productivity of napier and guatemala grasses in western Kenya. East African Agricultural and Forestry Journal 37:206-210.


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