Potential for the utilization of agro and marine by-products as sources of protein supplements for feeding dairy cows in Zanzibar

The IAEA provided various opportunities for extension and research to improve small-scale dairy farming in Zanzibar, a particular emphasis being the development of packages to improve utilization of the locally available feed resources in order to overcome nutritional problems and increase milk production.


Over the last century, poor nutritive value of the natural growing pastures has been described as one of the major constraints affecting dairy production systems in the tropical Eastern Africa, including Zanzibar. Due to the unpredictable physical constraints such as climate and shortage of rainfall for year-round forage cultivation, feeding is highly dependent on wild grasses of high fibre content but low in protein. On the other hand, potential feed resources with superior nutrient compositions are available in the region, but their utilization may be of limited due to the lack of information and skills among the farmers on processing and dietary formulations.

The IAEA TC Project Livestock Development after Tsetse Eradication provided various opportunities for extension and research to improve small-scale dairy farming in Zanzibar, a particular emphasis being the development of packages to improve utilization of the locally available feed resources in order to overcome nutritional problems and increase milk production. Over 20 extension workers and 480 smallholder farmers received training in this field and have participated in the project since 2001. A three-year research project also helped to describe the present dairy feeding systems, identify their prevailing problems and devise some possible solutions.

The three major dairy feeding systems in Zanzibar (and the proportion of farmers under each system) are; Intensive "cut and carry" whereby cows are exclusively confined and receive both forage and concentrates in-door (70%); Semi-intensive, where the cows are grazed during the day and are confined at night with further feeding and supplementation (12%); Extensive, where cows are exclusively grazed outdoor with no additional feeding or supplementation (6%).

Utilization of industrial farm by-products for feeding dairy cows

Unprocessed coconuts Information regarding status of utilizing farm byproducts was obtained through a cross-sectional survey conducted between July and October 2003. The survey involved 202 farmers across all six districts of the island.

Over 90% of farmers interviewed used industrial farm by-products to feed their milking cows; the majority of these were the ones ranking livestock as a major source of their household income. The majority of farmers offered maize bran, wheat by-products, and less frequently rice by-products. Unfortunately, 54% of those who fed concentrates did not include any recognized source of protein supplement.

Potential sources of protein supplements available on the island

Mechanical extraction of coconut oil Coconut, being the second major cash crop grown in Zanzibar, can play a great role as a potential source of plant protein for feeding dairy cows. Coconut oil is extracted for cooking and soap production in series of steps that results in a residue called "copra cake" as a by-product. Most farmers in Zanzibar have not utilized this resource adequately, even though copra is widely available and much cheaper than all cereal byproducts.

Five local factories in town produce approximately 1000 tons of copra cake per year.

The copra cake is obtained through either whole dried nut direct from the farm, or nuts previously squeezed to provide cooking oil in households. Copra cake from a whole dried nut has significantly higher protein (25 vs. 14g/100g DM) and fat (22 vs. 11g/100g DM) content than do alternative feed sources.

Another possible source of protein is dried fish wastes (gills and guts). At least 84% of farmers interviewed had never heard of the use of fish wastes in dairy diets. Of those who did, none of them had ever tried it on their farms.

Annual fish catch and the corresponding fish waste yields 2001 - 2004 Batches of 17 fish species were collected and dissected to determine the proportion of wastes yield from individual species as well as chemical composition of their body parts. The study showed an average of 2,040t of fish wastes being produced annually, between 2001 and 2004. This amount was extractable from an annual fish catch of 22,773t. Fish catches on Zanzibar have increased over the last four years, which indicates the potential for an increased quantity of fish waste may be produced in the future.

The overall protein content of the identified species varied significantly (57.68±2.33; P<0.001), with the lowest and highest levels being 37.5 and 71.0/100g DM respectively.

On farm supplementation of dairy cow diets with the locally available copra cake

A batch of dressed mackerels lying beside its valuable wastes Fifty crossbred dairy cows were involved in a four-week on-farm feeding trial that was conducted in February-March 2004. After a covariate period, half of the cows were fed on the treatment diet that consisted of 35% copra cake (18.6% protein) while the other cows were fed on wheat by-products (17% protein) as a control diet.

Inclusion of copra in the diet failed to improve milk yields but significantly increased butter fat percentage in milk from 3.79±0.25 to 4.65±0.25. Most local consumers in Zanzibar prefer full cream milk and also a good price is offered when sold at the milk plant. In addition, farmers were also able to reduce feeding costs; the concentrate cost per kg of milk was 46.4TShs on the control diet and 39.4Tshs in copra diet.

Formulation and on-farm feeding trial of the fish-copra diets

A Jersey-cross cow eating the fish:copra cake mixture The second on-farm trial, also with a covariate design, was implemented in June-July 2005 to determine the effect of feeding different levels of fish:copra diets on the milk yield, weight gains, protein and butterfat content. Another sample of 45 dairy cows was exposed on two iso-nitrogenous diets (18% CP) containing either 24% of 2:1 fish:copra or 35% of 2:1 copra:fish diets, and maize bran (11%CP) only as a control diet.

On average, inclusion of two parts of fish wastes in the diet increased milk yield by 1.2kg of milk per cow per day compared to the control diet and significantly increased protein content of the milk from 3.5% on the control diet to 4.1%. , inclusion of two parts of copra in the diet increased weight gain from 95g on the control diet to 478g per day. In addition, no trace of fish taint was detected in the milk, according to a blind tasting conducted by a panel of 12 regular milk drinkers.

The cost analysis for feeding different dietary concentrates

It was encouraging that over 90% of farmers visited after the trials gave their vote of confidence to all three experimental diets compared to the control diets and at least 50% of them formulated their own diets for their cows. More farmers are especially curious of learning the skills of fish waste processing, diet formulation and feeding.

Due to the rapid increase of its price, the use of maize bran in any combination seems to be of little advantage and therefore, incorporation of protein concentrates with wheat byproducts would seem to be the best alternative so far.

Table 1. The recent costs of common dairy cow feed ingredients (December 2005)

Feedstuff TSh/kg Fresh weight TSh/MJ ME
Maize bran 200 16.7
Wheat bran 87.5 10.9
Wheat pollard 92.9 9.3
Copra cake 60 4.7
Dried fish waste 120 8.6
Mineral mix 750 -