Feed utilisation, growth performance and carcass characteristics of Tanzania shorthorn zebu cattle fed rice straws under traditional finish feeding system
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Date
2024-05
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Sokoine University of Agriculture
Abstract
Tanzania has 36.6 million cattle and is one of the countries with the
largest cattle population in Africa. Of the 36.6 million cattle, 96% are
indigenous cattle and the majority of them belong to the Tanzania
Shorthorn Zebu (TSHZ) breed. The TSHZ are kept under low input
systems and grazed extensively in the communal rangelands. The
low input management practices result into poor performance that
has led to red meat production-demand imbalance in the country.
The mismatch between supply and demand of beef is aggravated by
the fast human population and economic growth. Some local cattle
producers engage in feedlot practices as a means to increase beef
production and capture the existing red meat market and hence,
increase income generation to support their livelihoods. Most feedlot
practitioners feed natural grasses including Cenchrus ciliaris hay to
cattle as the basal diet and energy-based concentrates as
supplement. However, hay usage is limited by its unavailability and
high price, which necessitates farmers to look for alternative least
cost basal diets such as cereal crop residues. Rice straw is among
the cereal crop residues which are abundantly available and cheap
in agro-pastoral communities of Tanzania. Despite the abundant
availability of rice straws, these straws have high proportion of
indigestible carbohydrate which limits their utilisation as a basal diet
for fattening cattle. Treatment with urea can improve the nutritional
value of rice straws and, hence, high performance of the fattened
cattle. Therefore, the current study was conducted to evaluate the
effects of partial or complete substitution of C. ciliaris hay with urea
treated or untreated rice straws on feed utilisation, growth
performance, carcass and meat characteristics of TSHZ. The current
study was conducted at Mtanana village in Kongwa district, located
about 82 km from Dodoma capital city in central Tanzania. Fifty (50)
bulls with initial mean (± SD) weight of 132.4 ± 26.7 kg and age of
2.5 - 3 years were used in the experiment. The bulls were kept
under total confinement and assigned randomly to five dietary
treatments with 10 animals per treatment. The dietary treatments were used as basal diets and included C. ciliaris hay only (CCH),
untreated rice straws (URS), urea treated rice straws (TRS),
combination of untreated rice straws and hay (URH) and
combination of urea treated rice straws and hay (TRH). In addition to
the basal diet, all animals were fed the same supplementary diet
comprised of maize bran (53%), molasses (25%), sunflower seed
cake (20%), mineral premix (1.5%) and table salt (0.5%). The
feeding trial took 84 days and at the end of the experiment, the
experimental animals were evaluated for feed intake, weight gain,
daily weight gain, percentage profit return, carcass characteristics
and meat quality. Throughout the experimental period, clean water
was provided ad libitum to all experimental animals. The results
indicate differences (p < 0.001) in basal diet intake whereby animals
under TRS had the highest value (1.6 ± 0.02 kg DM/day) and those
on CCH
had the lowest (1.3 ± 0.2 kg DM/day). Similarly,
metabolisable energy intake was highest for animals fed TRS (86.0
± 0.7 MJ/day) and lowest for those on CCH (72.0 ± 0.7 MJ/day).
The animals fed TRH had the highest weight gain (64.7 ± 4.4 kg)
and average daily gain (770 ± 0.1 g/day) while those on URS had
the lowest weight gain (50.3 ± 4.4 kg) and average daily gain (599 ±
0.1 g/day). Also, feed conversion ratio varied (p < 0.001) among
treatments and was lowest for animals on TRH (8.9 ± 0.1) and
highest for animals on URS (11.9 ± 0.1), indicating that animals on
TRH were more effective in converting feed to live weight. Animals
fed URH had the highest hot carcass weight and some linear
carcass measurements such as chest depth and hind limb
circumference. The final meat pH was slightly higher in all animals
subjected to different dietary treatments and was above the
recommended value of 5.8. This resulted into dark red meat,
probably due to the stress experienced by the animals at slaughter.
Meat fat content was lower in animals fed TRS (10.6%) than in
animals fed TRH (13.9%) and URS (11.9%). The animals on TRS
had the highest proportion of lean (72.3%) compared to the animals
on other treatments. The animals on TRH showed the least cost
(TZS 5,244/=) for gaining one kilogram of live weight. However, thehighest percentage profit return was observed in animals fed TRS
(32.3%) while those fed CCH had the least (27.3%). Therefore, it is
concluded that TRS is the best basal diet for fattening indigenous
cattle because the animals fed this diet showed higher percentage
profit margin, proportion of lean and lower fat and total lipid contents
compared to those on other diets.
Description
Master of Science Degree in Tropical Animal Production
Keywords
Crop residues, Cattle fattening, Indigenous cattle, Feed conversion ration, Growth rate, Gross Margin, Traditional feedlot system, Lineal carcass measurements, Hot carcass weight, Meat tenderness