Constraints to use of natural pasture for ruminants production along the eastern coast of Tanzania

P Y Kavana, J B Kizima and B J Masakia

Livestock Research Centre, P.O. Box 5016, Tanga
pkavana2001@yahoo.com   or   lrc@kaributanga.com

Abstract

Commercialisation of agriculture in Tanzania requires a constellation of various services from different sectors. Findings obtained in agricultural research institutes should be available to the clients and the public at large for success of Agricultural Sector Development Programme (ASDP). Livestock Research Centre in Tanga Tanzania conducted studies for improvement of livestock production along the eastern coast of Tanzania.

Findings on utilization of natural pasture indicated that crude protein content of natural grasses ranged between 32.2 to 98.2 g/kgDM. Bothriochloa radicans identified as the lowest in crude protein content and digestibility among the natural grasses investigated. It was found that supplementation of dairy animals that rely on natural grasses, as basal diet is inevitable for realization of high milk yields. Digitaria mombasana was found to be a suitable grass for grazing animals along the eastern coast of Tanzania. The optimum-stocking rate for growing steers along the eastern coast of Tanzania was found to be 1.2 ha/animal.

Key words: Basal diet, commercialisation of agriculture, eastern coast of Tanzania, natural pasture

Introduction

Natural pasture species have been the main source of feed for ruminants along the eastern coast of Tanzania (Msanga 1997 and Msangi 2001. However, bimodal distribution of rainfall, uneven seasonal growth and availability of pasture has been considered as the major limitations to constant supply of forage for ruminants. Experiences from inland of Tanzania have shown that low quality and quantity of grass pastures is so common such that minimum nutrient requirements for maintenance and production of animals could not be met (Kakengi et al 1999). Nutrition of dairy cattle has been a subject of extensive investigation in several decades of the last century in eastern coast of Tanzania. Indeed one would expect that enough data has been analysed and results could be reached easily. Unfortunately, this situation does not exist as most of the data are discretely bound to scientists involved in those findings. This situation makes rather difficult to advise the public appropriately on ruminants’ production investments along the eastern coast of Tanzania. The Agricultural Sector Development Programme of Tanzania insists on creation of favourable climate for commercialisation of agriculture. Success of the programme requires availability of information in various sub-sectors. In that manner, amalgamated body of knowledge created by Livestock Research Scientists in Tanga worth publication for public consumption. Some efforts have been done to establish the potential of various pasture species for livestock production in eastern coast of Tanzania. The findings deemed important for entrepreneurs who intend to invest in ruminants’ production enterprises along the eastern coast of Tanzania.
 

Materials and methods

On station studies

Various natural pasture species were collected from the fields in early 1990s for chemical analyses and in-vitro digestibility tests. In-vitro digestibility was conducted according to Tilley and Terry (1963). Investigation on performance of steers grazing on natural pasture under coconut trees was conducted using 36 hectors divided into paddocks. The stocking rates investigated were 0.6:1, 1.2:1, 1.8:1, 2:1 and 3:1 (ha:animal). A total number of 16 growing steers were used for the study with an average weight of 230 kg at the beginning of a trial. Weights of the animals were measured on monthly basis for calculation of weight gain. The animals were allowed to graze for 10 hours before taking them back to the common kraal. Botanical composition of the paddocks was analysed before and after commencement of the trial.

On farm evaluation study

Feeding values of various pasture species were investigated based on performance of animals under smallholder dairy farmers’ conditions. The study began on October 1995 to September 1996 and repeated from September 2001 to December 2002. Thirty participating farmers were involved in feeding trial. The animals used were crossbred (Friesian x Boran) owned by the farmers. Milk yields were determined daily using measuring cylinders and recorded. Forage samples were taken on weekly basis and bulked to obtain a monthly sample for chemical analyses. Dry matter and digestible dry matter intake were estimated according to Shem (1993).

Supplementary ration

Lactating animals were supplemented using home made ration with the composition shown in Table 1. Animals were supplemented during milking by providing 4 kg of supplementary ration except animals that were provided with native grasses. Each animal was given 2 kg of the ration in the morning and the other 2 kg was provided in the evening.

Results and discussion

Results shown in Table 2 indicated that crude protein content of natural grasses ranged between 32.2 to 98.2 g/kgDM.

Bothriochloa radicans had the lowest crude protein content that consequently resulted into low digestibility. Naturally, Bothriochloa radicans is not as leafy as Bothriochloa insculpta that had relatively higher crude protein content and digestibility. Most of the common natural pasture species investigated were low (<500 g/kgDM) in dry matter and organic matter digestibility. Setaria sphacelata had the highest digestibility among the natural pastures investigated. The same species had the highest crude protein content. This observation suggests that dependence on natural grass species available along the eastern coast of Tanzania as basal diet for ruminants, requires supplementation strategies in order to improve high nutrient gain by the animals.

Results in Table 3 indicated that the animals fed Pennisetum purpureum as basal diet produced the highest amount of milk/cow/day.

The highest dry matter intake among the five grass species was observed in Pennisetum purpureum that could resulted in high nutrient intake as reflected by the highest digestible dry matter intake estimated compared to the other grass species. Lowest milk yields were obtained from cows that were fed native grasses alone that included Urochloa pullulans, Digitaria mombasana, Bothriochloa radicans and Bothriochloa insculpta. Supplementation of cassava leaves silage to the animals that fed native grasses improved milk production.

Results on botanical composition of plants in paddocks before and after trial are shown in Table 4. Digitaria mombasana was dominant and not depleted among the natural pasture species subjected to different stocking rates.

The findings suggest that the species is a suitable natural pasture for ruminants grazing along the eastern coast of Tanzania. The species seemed to be well adapted to the coastal belt environment.

Results on performance of growing steers are shown in figure 1.

The maximum output of pasture in terms of weight gain of steers occurred at a stocking rate of 1.2 ha/animal. High stocking rates (>1.2 ha/animal) resulted in over-grazing that was reflected by increase in undesirable plants shown in  Table 4. Weight gain of steers decreased after a stocking rate of 1.2 ha/animal. A reason for that could be the animals wasted some time by moving around the ample space in big paddocks for selection of plants to consume. Wastage of time could affect the performance of the animals because the grazing time was strictly 10 hours.

Conclusions

• Feed supplementation is important for dairy animals that rely on native grasses as basal diet in order to realize high milk yields along the eastern coast of Tanzania.

  
  

• The maximum output of natural pasture in terms of weight gain of growing steers can be reached at a stocking rate of 1.2 ha/animal in eastern coast of Tanzania.

  
  

• Digitaria mombasana is a suitable natural pasture for grazing animals along the eastern coast of Tanzania.

Acknowledgement

The authors wish to acknowledge the Government of the United Republic of Tanzania for funding and facilities that enabled acquisition and processing of data.

Reference

Kakengi A M, Shem N M and Otsyina P 1999 Performance of grazing cattle in semi-arid tropics supplemented with Leucaena leucocephala leaf meal and its cost benefit analysis. In: Proceedings of the 26^th Scientific Conference of Tanzania Society of Animal Production. (Edited by Mbaga SH, Ndemanisho, E.E and Kakengi A.M.V.). 3 – 5 August 1999, Tengeru, Arusha, Tanzania, pp 176 – 187

Msanga Y N 1997 Smallholder dairying in Northeast  Coastal Tanzania: Productivity of Crossbred cattle and Calf Rearing Systems. PhD Thesis. The University of Reading

Msangi B S J 2001 Studies in smallholder dairying along the coast of Tanzania with special reference to influence of feeding and supplementation on reproduction and lactation in crossbred cows, PhD Thesis, The University of Reading, United Kingdom

Shem M N 1993 Evaluation of the locally available feed resources on smallholder farms on the slopes of Mt. Kilimanjaro.  Ph.D Thesis, University of Aberdeen

Tilley J M A and Terry R A 1963 A two-stage technique for in-vitro digestion of forage crops. Journal of British Grassland Society, 18:104 – 111

Received 14 February 2007; 1 October 2007; Published 12 December 2007

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