SIGNIFICANCE OF BROWSES IN THE NUTRITION OF TSWANA GOATS(LOS FORRAJES LEÑOSOS EN LA NUTRICIÓN DE LAS CABRAS TSWANA)

A.A. Aganga

Description

Abstract
The nutritional value of shrubs and tree fodders browsed by Tswana goats in Botswana were evaluated. In the first study, seeds from twenty browse species were analysed. Nutrient composition of the seeds varied widely. Crude protein content of Bauhania petersiana was 6.42 g/100g while Sterculia africana was 35.59 g/100g. The second study showed that twigs from five browses varied in tannin and nutrient composition. Acacia tortilis and Grewia flava leaves and twigs had similar crude protein content but their tannin contents differ significantly (p<0.05). The third study was to evaluate available browse resources for Tswana goats reared extensively in South East Botswana. The most commonly occuring species were Acacia erioloba, A. tortilis, Dichrostachys cinerea, G. flava and Terminalia seracea. Browses varied in their seasonal availability but A. tortilis, G. flava and T. seracea were present on the ranges all year round. The fourth study was a feeding trial using yearling males fed buffalo grass hay ( Buchloe dactyloides) as basal diet and Acacia nilotica or D. cinerea as supplements to evaluate animal performance on these browses. The fifth study demostrated that A. erubescens and buffalo grass hay fed as supplement to grazing Tswana goats improved their weight gains.
Resumen
Se evaluó el valor nutritivo de arbustos y árboles ramoneados por cabras Tswana en Botswana. Primero se analizaron las semillas de veinte especies leñosas. La composición nutritiva de las semillas varió ampliamente: el porcentaje de proteína bruta osciló entre 6,42 de Bauhania petersiana y 35,59 de Sterculia africana. El segundo estudio mostró que las hojas y brotes de cinco especies leñosas variaron en el nivel de taninos y composición nutritiva. Las hojas y brotes de Acacia tortilis y Grewia flava tienen niveles similares de proteína bruta, pero diferentes (p<0,05) de taninos. El tercer estudio se llevó a cabo para evaluar los recursos leñosos disponibles para las cabras Tswana explotadas en régimen extensivo en el Sudeste de Botswana. Las especies más frecuentes fueron Acacia erioloba, A. tortilis, Dichrostachys cinerea, G. flava y Terminalia seracea. La disponibilidad de los recursos varió estacionalmente pero A. tortilis, G. flava y T. seracea, se encontraron disponibles todo el año. El cuarto estudio fue una experiencia de alimentación usando chivos, que fueron alimentados con heno de Buchloe dactyloides como dieta basal y Acacia nilotica o D. cinerea como suplementos y heno de alfalfa para el grupo control para evaluar la eficacia de dichos recursos leñosos en la alimentación. El quinto estudio evaluó durante 98 días la utilidad de Acacia erubescens y suplemento de heno de B. dactyloides, para pastoreo de las cabras Tswana. Dieciseis chivos Tswana castrados fueron pesados y aleatoriamente distribuidos en cuatro grupos de cuatro repeticiones en un diseño completamente al azar. El estudio demostró que la suplementación con A. erubescens y el heno de B. dactyloides, mejoró la ganancia de peso de las cabras Tswana en pastoreo.

Sujets

• Intake
• Ingestión

Informations

• Publié par: erevistas
• Publié le: 01 janvier 2000
• Nombre de lectures: 13
• Langue: English

Extrait

SIGNIFICANCE OF BROWSES IN THE NUTRITION OF
TSWANA GOATS
LOS FORRAJES LEÑOSOS EN LA NUTRICIÓN DE LAS CABRAS TSWANA
Aganga, A.A., T. Adogla Bessa, U.J.Omphile and K. Tshireletso
Department of Animal Science and Production. Botswana College of Agriculture. Private Bag 0027.
Gaborone. Botswana.
ADDITIONAL KEYWORDS PALABRAS CLAVE ADICIONALES
Nutrient composition. Intake. Composición nutritiva. Ingestión.
SUMMARY
grass hay fed as supplement to grazing TswanaThe nutritional value of shrubs and tree
fodders browsed by Tswana goats in Botswana goats improved their weight gains.
were evaluated. In the first study, seeds from
twenty browse species were analysed. Nutrient
composition of the seeds varied widely. Crude RESUMEN
protein content of Bauhania petersiana was
Se evaluó el valor nutritivo de arbustos y6.42 g/100g while Sterculia africana was 35.59
g/100g. árboles ramoneados por cabras Tswana en
Botswana. Primero se analizaron las semillas deThe second study showed that twigs from
five browses varied in tannin and nutrient veinte especies leñosas. La composición nutri
tiva de las semillas varió ampliamente: el porcen composition. Acacia tortilis and Grewia flava
leaves and twigs had similar crude protein content taje de proteína bruta osciló entre 6,42 de
Bauhania petersiana y 35,59 de Sterculia afri but their tannin contents differ significantly
(p<0.05). The third study was to evaluate cana.
El segundo estudio mostró que las hojas yavailable browse resources for Tswana goats
reared extensively in South East Botswana. The brotes de cinco especies leñosas variaron en el
nivel de taninos y composición nutritiva. Lasmost commonly occuring species were Acacia
erioloba, A. tortilis, Dichrostachys cinerea, G. hojas y brotes de Acacia tortilis y Grewia flava
tienen niveles similares de proteína bruta, peroflava and Terminalia seracea. Browses varied
in their seasonal availability but A. tortilis , G. flava diferentes (p<0,05) de taninos. El tercer estudio
se llevó a cabo para evaluar los recursos leño and T. seracea were present on the ranges all
year round. The fourth study was a feeding trial sos disponibles para las cabras Tswana explo
tadas en régimen extensivo en el Sudeste deusing yearling males fed buffalo grass hay
(Buchloe dactyloides) as basal diet and Acacia Botswana. Las especies más frecuentes fueron
Acacia erioloba, A. tortilis, Dichrostachysnilotica or D. cinerea as supplements to evaluate
animal performance on these browses. The fifth cinerea, G. flava y Terminalia seracea. La dis
ponibilidad de los recursos varió estacionalmentestudy demostrated that A. erubescens and buffalo
Arch. Zootec. 49: 469 480. 2000.AGANGA, ADOGLA BESSA, OMPHILE AND TSHIRELETSO
pero A. tortilis, G. flava y T. seracea, se encon of browse in the diet of herbivores in
traron disponibles todo el año. El cuarto estudio Botswana is reflected in reports by
fue una experiencia de alimentación usando Aganga et al. 1998 and Aganga, 1999.
chivos, que fueron alimentados con heno de The nutritional importance of browse
Buchloe dactyloides como dieta basal y Acacia is especially significant for free ranging
nilotica o D. cinerea como suplementos y heno goats in extensive communal system
de alfalfa para el grupo control para evaluar la of production. Goats have a great
eficacia de dichos recursos leñosos en la alimen tendency to change their diet according
tación. El quinto estudio evaluó durante 98 días to seasonal feed availability and growth
la utilidad de Acacia erubescens y suplemento
rate of plants. Some parts of browse
de heno de B. dactyloides, para pastoreo de las
species can be found during the dry
cabras Tswana. Dieciseis chivos Tswana cas
season (winter) and these include pods,
trados fueron pesados y aleatoriamente distri
fruits and leaves of evergreens. Most
buidos en cuatro grupos de cuatro repeticiones
trees/shrubs produce their leaves during
en un diseño completamente al azar. El estudio
wet season (summer), thus browse is
demostró que la suplementación con A.
more available during the springerubescens y el heno de B. dactyloides, mejoró
(August to May) (Palgrave, 1983). Thisla ganancia de peso de las cabras Tswana en
study therefore is to evaluate feedpastoreo.
potential of browses for nutrient and
tannin composition, availability on the
range and utilisation as supplementaryINTRODUCTION
feed for Tswana goats.
The quantity and quality of water
are limiting factors in crop and forage
MATERIALS AND METHODSproduction in Botswana. Therefore,
ruminant livestock depends predomi
Five trials were conducted tonantly on natural pastures and range,
evaluate feed value of browse inwith the addition of some imported raw
Tswana goats feeding and nutrition. Infeed ingredients mainly from South
trials 1 and 2, the nutrient compositionAfrica and Zimbabwe that are
(proximate, macro and micro minerals)processed locally into concentrates.
and tannins were determined. In trial 3,Feed shortage is the major constraint
available browse plants under extensiveaffecting the development of the
range condition were evaluated, whilecountry's animal industry (Aganga and
trials 4 and 5 were conducted to studyMoganetsi, 1998). Browse leaves and
performance of Tswana goats on somepods form a natural part of the diet of
browse species as supplements.goats which meets over 60 per cent of
the forage requirement and have been
TRIAL 1used by traditional farmers as sources
of forage in Botswana. There are Seeds (mature, dry) from twenty
several types of leguminous and non locally available browse species, nine
leguminous trees used as forage by belonging to Mimosodeae, four to
goats but the predominant genus in Caesalpinioideae and one each to
Botswana is Acacias. Feed potential Bombacaceae, Euphorbiaceae, Com
Archivos de zootecnia vol. 49, núm. 188, p. 470.SIGNIFICANCE OF BROWSES IN THE NUTRITION OF TSWANA GOATS
bretaceae, Papilionoideae, Ochnaceae, were dried in a laboratory oven at 50
Rubiaceae and Sterculiaceae subfa °C for 72 hours then ground to pass
milies collected from the savanna and through a 1 mm sieve. The vegetation
woodlands of Botswana were analysed of the study area is a thorn bush
for chemical composition and in vitro savanna with a sparse cover of annual
dry matter digestibility. grasses, herbs and shrubs. Annual
rainfall here ranges from 280 to 500
TRIAL 2 mm, and average temperatures are 28
Twigs and leaves from five indige 39°C in summer and 15 26°C in winter.
nous browse species namely Kirkia
accuminata Oliver, Acacia karoo TRIAL 4
Hayne, Acacia tortilis (Forsk.) Hayne, The experiment was conducted at
Acacia nilotica (L.) Willd ex Delile Botswana College of Agriculture
and Grewia flava DC obtained from Content farm, Gaborone for a period
Botswana rangelands were evaluated. of 120 days. Twenty four Tswana
yearling male goats (average initial
TRIAL 3 body weight 12.8 kg) were divided into
The study was carried out at two three groups of eight animals in a
sites at Kopong and Mosinki lands in completely randomised design. Buffalo
Kweneng district of South East grass hay (Buchloe dactyloides)
Botswana. In each study area, three constituted 60 per cent of the ration on
sampling locations were evaluated each dry matter basis as basal diet to all
being 7 km from the other. Within each goats. The control group received
sampling location, three replications of lucerne hay (Medicago sativa) as
20 m by 20 m were marked. Replicates supplement. The other two groups were
were 100 m apart. Sampling was donesupplemented with Dichrostachys
on marked plants, every two months cinerea (L.) Wight & Arn (Treatment
for a period of twelve months, thus 1) and A. nilotica (Treatment 2).
ending up with six batches of samples.Water was provided daily and the goats
were individually penned under aSampling was done by cutting the
leaves and twigs of the browse plants. common roof. Cleaning of the pens
Shrub density was determined for eachand removal of left overs of the
sampling site (i.e. the number of shrubsprevious day was done daily before
in a 20 m by 20 m area) and this placement of the day's ration. Water
converted to shrubs per hectare of and feed left were measured daily
land. Shrubs and tree fodders were while the goats were weighed every
sampled to determine the yield of the two weeks, before the morning feeding.
area during different periods of the
year. Patterns of utilisation of different TRIAL 5
The experiment was conducted atparts of browseable tree species were
determined from visual observations Botswana College of Agriculture, goats
by the researchers with the assistance unit, for a period of 98 days. Castrated
of agricultural extension workers and Tswana goats, between the age of 10
goat farmers. Pods, leaves and fruits 12 months were chosen from the
Archivos de zootecnia vol. 49, núm. 188, p. 471.AGANGA, ADOGLA BESSA, OMPHILE AND TSHIRELETSO
College's herd and allocated to four Data collected were subjected to the
groups (control, treatments 1, 2 and 3)analysis of variance (Steel and Torrie,
of four replicates each with an avera 1980).
ge initial body weight of 12.7 kg.
The go