reproductive performances were compared between purebred Menz (MM), ... contemporary purebred MM sheep while 75% WM sheep were only 0.5 kg heavier.
[Proceedings of the 6th and 7th Annual Regional Conference on Completed Livestock Research Activities]
2011-2012
Growth and Reproductive Performance of Menz, Washera x Menz and Bonga x Menz Sheep in the Cool Highlands of Central Ethiopia Sisay Lemma, Solomon Gizaw, Ayele Abebe and Tesfaye Getachew Debre Birhan Agriccultural Research Center
Abstract A crossbreeding study between local sheep breeds was conducted at DebreBirhan Agricultural Research Center aimed at improving mutton production in the meat-only subsystem in the cool highlands of central Ethiopia. Growth, carcass and reproductive performances were compared between purebred Menz (MM), Washera x Menz (WM) and Bonga x Menz (BM) crossbred sheep. Reproductive traits and productivity measurements were calculated for purebred MM and 50% WM and 50% BM ewes. There was no significant difference (P> 0.05) in body weight at birth and weaning, and in pre-weaning average daily gain recorded for purebred Menz lambs and their 50% crosses with Washera and Bonga sheep. Male sheep of purebred MM, 50% WM and 50% BM were supplemented with either 0, 200 or 400 g head-1day-1 of commercial concentrate for an average period of 240 days in addition to grazing on natural pastures. Genotype and supplementation had significant effects on yearling weight and carcass weight: 50% BM grew faster and were heavier at yearling than both 50% WM and MM (21.7 ± 0.5 vs. 19.9 ± 0.5 and 20.1 ± 0.5 kg; P< 0.05) and produced more kg of meat (9.5 ± 0.4 vs. 8.5 ± 0.3 and 8.2 ± 0.3 kg; P< 0.05). Sheep supplemented at 200 and 400 g head-1day-1were heavier than unsupplemented controls at yearling (21.8 ± 0.5 and 25.0 ± 0.5 vs. 14.9 ± 0.6 kg; P< 0.001) and produced more meat (9.2 ± 0.3 and 11.6 ± 0.3 vs. 5.3 ± 0.3 kg; P< 0.0001). Dressing percent was influenced by supplementation (40.4 ± 0.6 and 42.9 ± 0.6 vs. 34.2 ± 0.6; P< 0.001) but not by genotype. Crossbred lambs with 75% BM blood level exceeded both purebred MM and 75% WM lambs in all weights recorded from birth to yearling age. At yearling age, 75% BM crossbreds weighed 3.7 kg heavier than their contemporary purebred MM sheep while 75% WM sheep were only 0.5 kg heavier than MM sheep. There was no significant difference (P> 0.05) in age at first lambing, lambing interval, annual reproduction rate and productivity measurements between purebred MM, 50% BM and 50%WM crossbred ewes. Compared to crossbreeding, the effect of improved feeding conditions was more prominent in all genotype groups. The results of this study indicate that 75% BM crossbred lambs were significantly heavier than MM lambs at yearling but this should be verified under the traditional sheep production system in the target area.
words: Menz-type, Bonga sheep, Washera supplementation, growth, carcass, reproduction.
Key
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sheep,
crossbreeding,
[Proceedings of the 6th and 7th Annual Regional Conference on Completed Livestock Research Activities]
2011-2012
Introduction Washera and Bonga sheep are indigenous sheep breeds in Ethiopia. Washera sheep is found in the moist and sub-moist highlands of northwestern Ethiopia, south of Lake Tana (East and West Gojam and Awi zones of the Amhara region) while Bonga sheep is found in the humid highlands of western Ethiopia (Bonga and Jima zones of the Oromiya region). Washera (Mengistie et al., 2011) and Bonga (Belay Berhanu and Haile Aynalem, 2009) sheep breeds have faster growth and larger body size and better reproductive performances than Menz sheep, both with potential for commercial mutton production. Apart from excellent growth performance, they are also moderately prolific with twinning rate of 20% as compared to 5 % in Menz sheep. In addition to the coarse wool Awassi sheep, the two indigenous sheep breeds can be used as improver breeds for crossbreeding with the local Menz type sheep in the meat-only sub-system in North Shewa (around Debre Birhan) zone of the Amhara region. In the meat-only subsystem where the tradition of fleece processing does not exist, the long fleece from Awassi x Menz crosses appears unhygienic, adds management complications and provides favorable breeding habitat for external parasites. The aim is to utilize non-genetic effects and crossbreeding enables to combine favorable attributes from different breeds such as productive and adaptive traits and create a new breed following intensive selection. The chances of success, biologically or in terms of acceptance by farmers and local markets, are usually higher than when exotics are used. This paper presents data on the comparative performance in growth, carcass yield and reproductive performances of pure Menz sheep, and Washera x Menz and Bonga x Menz crosses under on-station management at Debre Birhan Research Center in the cool highlands of central Ethiopia.
Materials and methods Study location Data used in this study was obtained from on-station experiment conducted from 2004 to 2010 at Debre Birhan Research Center (DBARC). DBARC is located some 120 km northeast of AddisAbaba, at an altitude of 2780 masl. The climate is characterized by a long rainy season (June to September) accounting for about 75% of the annual rainfall, a short rainy season (March to May) and a dry season (October to January). Annual rainfall at the station averaged 920 mm. The average monthly minimum temperature ranged from 1.3C in November to 8C in August, while the average monthly maximum temperature ranged from 18.6°C in August to 23.4°C in May. Andropogon grasses (A. longipes) with a variable proportion of legumes (Trifolium spp.) dominate the natural pasture of the station.
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[Proceedings of the 6th and 7th Annual Regional Conference on Completed Livestock Research Activities]
2011-2012
Animals and management Four hundred-and-eighty breeding ewes were purchase from farmers’ flocks and local markets in several selected Weredas of North Shewa. Sixty ram lambs (30 from each of Washera and Bonga sheep breeds) with an average age of 4-5 months old were bought from farmers’ flocks in their respective locality. Ram lambs were screened on-station based on individual growth performance over a period of 3-6 months. Finally, the best 8 rams out of 30 were selected for breeding purpose on the basis of average weight gain. Menz-type ewes were allocated by stratified random sampling based on body weight into 3 multi-sire mating groups. Breeding rams of Menz, Bonga and Washera sheep breeds were assigned randomly into each of the 3 groups of ewes for a mating period of 42 days. All ewes run as a single flock after the end of mating and managed similarly. They grazed on natural pasture during the day and supplemented at night in a concrete floored barn with hays from oat/vetch or natural pasture during periods of serious feed shortage and during lambing time. All animals were vaccinated against diseases common to the area, treated strategically for gastro-intestinal parasites, and sprayed against ecto-parasites. Progenies of pure Menz, 50% WM and 50% BM genotype were born in OctoberDecember 2004 and March-June 2005. Lambs were weaned at 90 days and kept separate from their dams. At weaning, male progenies from within each genotype group were allocated by stratified random sampling based on weaning weight to the following three feeding treatment groups: Group I: Natural pasture grazing only Group II: Natural pasture grazing + 200 g head-1day-1 commercial concentrate Group III: Natural pasture grazing + 400 g head-1day-1 commercial concentrate Sample lambs within each genotype x treatment subgroups were slaughtered at yearling for carcass evaluation. Ewe lambs born in the experiment were maintained for reproductive performance study. The first generation 50% Washera x Menz and 50% Bonga x Menz crossbred ewe lambs were backcrossed to pure Washera and Bonga breeding rams. The second generation crossbred lambs of 75% Washera x Menz and 75% Bonga x Menz were born between 2006 and 2009 and contemporary lambs of pure Menz sheep were born at the same time.
Measurements Initial local ewes were weighed every month and immediately after lambing. At birth progenies were identified to their dams, sex, birth type and genotype group, and were weighed at birth, at weaning (90 days of age) and fortnightly in between and monthly
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thereafter. Data D on body y weights bettween birth and a yearling age, and pre-weaning survivalof laambs were reecorded. Ewe reprodductive perforrmance traits such as age at first lambbing, lambingg interval, litter size att birth and weeaning were recorded r for pure Menz, 50% 5 Washeraa x Menz and 50% Boonga x Menz.
Data analyysis Data was annalysed with the t mixed efffects model off the General Linear Modeel (GLM) procedure of o SAS (SAS 9.00, 2002) software. s Thee fixed effectts of sex of laamb, year of birth andd lamb genottype group were w fitted to the model onn pre-weaning growth and survivaal of lambs. The T fixed effeects of year of birth, lamb genotype andd feeding level were fitted f in the model m in the analysis a of poost-weaning growth g perform mance of male lambs under supplemented and un-supplemeented conditioons. The sam me effects o carcass datta. Reproducttive traits except yearr of birth werre fitted in thhe analysis of were analyzzed by fitting g the fixed eff ffects of year and season of o lambing, parity p and dam genotyype group. The Duncan Muultiple Range Test was used to separate means.
Results an nd discussion Least squarre mean body y weights off lambs at birrth and weanning age, pre-weaning growth ratee and survival of Menz, 50% WM andd 50% BM laambs are presented in Table 1. Thhere was no siignificant diff fference (P >00.05) in body weight at birrth and at weaning, annd in pre-weaaning averagee daily gain recorded r for purebred p Menz lambs and their 500% crosses with w Washera and Bonga shheep. Body weights w of Meenz sheep recorded in this study att birth and weeaning fall within w the rangge of values reported nz sheep at Debre D Birhann station (Muukasa-Mugerw wa et al., for the indiigenous Men 1995); but were lower than t values reported in other o studies (Hassen et al., a 2002; T could be because thhe indigenouss Menz ewess used to Demeke et al., 2004). This p y primiparouus ewes. Pre-weaning produce exxperimental laambs were predominantly survival ratee was significcantly higher (P
