Evaluation of appropriate entry-age and period of stay in feedlot for optimal production of quality meat from Tanzanian long fat-tailed sheep
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Date
2013
Authors
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Journal ISSN
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Publisher
Sokoine University of Agriculture.
Abstract
Tanzanian long fat-tailed sheep (TLS) is among the three indigenous sheep genotypes of
which in most cases are of poor quality, hence take long time to reach slaughter weight
and produce carcasses of low uniformity and meat of low tenderness. Efforts to improve
the performance ofthe TLS are constrained by lack of knowledge on appropriate type and
amount of feed, age and the period to keep the animals in the feedlot. To address these
characteristics and distribution of main carcass tissues and meat quality of the TLS The
first study was a pilot experiment which evaluated carcass and meat characteristics from
castrates slaughtered directly from extensive system. In this study, a total of 40 TLS aged
9, 12, 15 and 18 months were purchased from the auction markets of Dodoma region and
slaughtered at Dodoma abattoir within one week of purchase. Data were recorded on
slaughter weight, carcass and non-carcass components weight, dressing percentage, tissue
composition, pH, temperature, tenderness of meat. The results showed that, slaughter
body weight (SBW) differed significantly (P<0.05) between the slaughter age groups of
9 to 18 months, ranging from 15.1 to 22.9 kg live weight, respectively. It was noted that,
with increasing slaughter age the proportion of gastro-intestinal tract (GIT) to SBW
increased (P<0.05). The older animals (15 and 18 months old), had significantly tougher
meat with 69.7 Ncm-2 than younger animals that had 49.0 Ncm-2 shear force values at
6 h post mortem. The second experiment involved a 3x4 factorial experiment to evaluate
the effects ofthree levels of concentrate feeding (LCF) and four ages at entry into feedlot
(AEF) on growth and killing out characteristics ofTLS. The LCF points were concentrate
feeding at 50 (LCF50), 75 (LCF75) and 100 (LCF 100) per cent on top of hay feeding.
The age at entry to feedlot (AEF) were 9 (AEF9), 12 (AEF 12), 15 (AEF 15) and 18
issues, three experiments were done to investigate growth performance, carcass
Tanzania. These animals are raised and finished on pastures under extensive system.
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(AEF18) months. Daily dry matter feed intake (DMI) and fortnightly live weight
slaughtered. After slaughter, weights of carcass and non-carcass components were
recorded. The right side half carcasses were jointed into seven primal cuts followed by
dissection into lean, bone and fat tissues for determination of tissue composition. The
DMI of hay decreased and concentrate increased (PO.OOl) with increasing LCF. There
was significant interaction between AEF and LCF for feed conversion ratio where AEF18
and poorest when subjected to LCF50 (21.5 kg feed to one kg tissue gain). The hot
carcass weight increased (P<0.05) with increasing slaughter age and dietary levels. The
tenderness of m. Longissmus thoracic et lumborum (LL), Semimembranosus (SM) and
Supraspinatus (SP) muscles increased (P<0.05) from 26.8 to 21.2Ncm-2 with aging
duration from day 0 to 9 days. The findings from this study reveals that AEF 12 under
LCF 100 were the optimal in terms of retail cuts size, tissue distribution and tenderness.
characteristics and meat quality of one year old TLS under seven periods of stay in
feedlot (DF). Seventy (70) animals were randomly allocated to seven treatments as 0
(DFO), 14 (DF14), 28 (DF28), 42 (DF42), 56 (DF56), 70 (DF70) and 84 (DF84) days of
stay in feedlot, each with 10 animals in a completely randomized block design. Animals
in DFO (control) were slaughtered immediately after being purchased from livestock
keepers or auction markets. The experimental animals in other periods were grouped into
two animals per pen and provided with ad libitum forage hay of Cenchrus ciliaris grass
and molasses based diet (MBD) to provide 10.9 MJ ME/kgDM and 160g CP kg/DM.
Daily feed intake and weekly live body measurements were recorded and a group of 10
Warner-Bratzler shear force (WBSF) values were evaluated from LL, SM and SP
were the most efficient when subjected to LCF 100 (9.88 kg feed to one kg tissue gain)
measurements were done for a period of 84 days after which the animals were
The third experiment focused on evaluation of growth performance, carcass
animals were slaughtered after each DF. The thaw loss (%), cooking loss (%) and
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muscles. The highest average daily gains (129.8 g/day) and lowest feed conversion ratio
increased (P<0.001) from 6.5 kg in DFO to 13.5 kg in DF84 with lowest shear force
results indicated that 42 days was optimal DF for production of high quality meat in one
year old TLS when in access to 100% ad libitum concentrate allowance and the wisdom
of aging such meat is in doubt in view of low shear force in muscles in these animals. The
profitability of feedlot Tanzanian long fat-tailed sheep would be realized when animals
of one year old are offered concentrate feeding above 75% level of ad libitum offer. This
is a point where highest daily gain, highest break-even weight gain and lowest break-even
and type and amount of feedlot diet as well as the days in feedlot will determine the size
of carcass and its composition
Description
PhD Thesis
Keywords
Entry-age, Optimal production, Quality meat, Long fat-tailed sheep