REGULAR ARTICLES

Pre-weaning growth performance of crossbred lambs(Dorper × indigenous sheep breeds) under semi-intensivemanagement in eastern Ethiopia

Tsegay Teklebrhan & Mengistu Urge & Yoseph Mekasha &

Merga Baissa

Accepted: 21 November 2013 /Published online: 5 December 2013# Springer Science+Business Media Dordrecht 2013

Abstract A study was conducted to assess the effect ofgenetic and non-genetic factors (litter size, sex of lamb, andparity of dam) on pre-weaning growth performance of cross-bred lambs (75 % Dorper (DR) 25 % indigenous lambs; and50 % Dorper 50 % indigenous lambs) under semi-intensivehusbandry practices in eastern Ethiopia. Data from a total of275 Dorper sire breed × indigenous (Blackhead Ogaden[BHO] and Hararghe Highland [HH]) crossbred lambs withdifferent genetic group of the parental breeds were collectedfor three consecutive years (2009 to 2011). Pre-weaninggrowth performance attributes of crossbred lambs studiedwere birth weight, weaning weight, and pre-weaning averagedaily gain. Data were analyzed using the GLM procedure ofSAS (2003). Breed group and non-genetic factors significant-ly affected pre-weaning growth performance. Lambs with75 % Dorper and 25 % indigenous had higher (P <0.01) birthweight than 50 % DR and 50 % HH but similar to 50 % DRand 50% BHO.Weaning weight and pre-weaning live weightgain were higher (P <0.01) for ¾DR¼BHO and ¾DR¼HHthan 50 % Dorper inheritance. Single-born lambs had higherweight at birth, weaning weight, and pre-weaning averagedaily gain as compared to twins. Sex comparison is significant(P <0.05) and male lambs recorded highest pre-weaninggrowth performance compared to female counterparts.Parity, season, and lambing year significantly (P <0.01) influ-enced the pre-weaning growth of crossbred lambs. Therefore,it could be concluded that 50–75 % Dorper inheritance im-proved pre-weaning growth performance of indigenousbreeds of Hararghe Highland and Blackhead Ogaden sheep.The result also suggested culling of ewes older than fourth

parity to improve the pre-weaning growth performance oflambs.

Keywords Average daily gain . Birth weight . Fixed effects .

Weaningweight

Introduction

Small ruminants are known to be valuable genetic resourcesfor meat, milk, and skin production in the tropics and sub-tropics. They play an important role in creating employmentopportunity, income generation, capital reserve, and improv-ing household nutrition. Being small in size, they may notrequire large housing space per head compared to cattle andcan easily be handled and managed by the rural community.

Ethiopia has nearly 26 million sheep which make a majorcontribution to the livelihoods of the people and to exportearnings (CSA 2010). However, similar to other tropicalcountries, the productivity of indigenous sheep is very lowmainly due to low genetic potential for functional traits ascompared to improved tropical and temperate breeds. Forexample, among indigenous breeds of Ethiopia, theHararghe Highland (HH) sheep had lower growth perfor-mance and carcass value as compared to the indigenousBlackhead Ogaden (BHO) sheep (Tsegay et al. 2013). Dueto these reasons, tropical countries have been implementingcrossbreeding of indigenous animals with improved exoticgenotypes to improve the genetic potential of indigenousanimals. In Ethiopia, crossbreeding has been undertaken byemploying several exotic breeds such as Bleu-du-Maine,Merino, Rambouillet, Romney, Hampshire, Corriedale, andAwassi (Tibbo 2006). However, efforts made so far did notbring significant change mainly because of sustainabilityproblems and less involvement of producers in the program.

T. Teklebrhan (*) :M. Urge :Y. Mekasha :M. BaissaCollege of Agriculture and Environmental Sciences, School ofAnimal and Range Sciences, Haramaya University, P.O. Box 236,Dire Dawa, Ethiopiae-mail: ttmamy06@gmail.com

Trop Anim Health Prod (2014) 46:455–460DOI 10.1007/s11250-013-0513-1

The Ethiopian Sheep and Goat Productivity ImprovementProgram (ESGPIP) evaluated the success and failure story ofthe previous crossbreeding efforts and imported tropicallyadapted sire breeds (i.e., Dorper (DR)) for a crossbreedingprogram. The Dorper sheep breed was developed in SouthAfrica, primarily for meat production, through crossingHorned Dorset rams and Blackhead Persian ewes. The breedis known to have performance characteristics similar to that ofwool sheep breeds (Fourie et al. 2009). Dorper crossbredlambs had higher average daily gain than indigenousEthiopian sheep breeds (Tsegay et al. 2013). Therefore, theDorper breed is suitable for crossbreeding business in varioustropical and subtropical regions.

ESGPIP launched a crossbreeding program in September2005 in Ethiopia using different indigenous breeds of ewe asdam breed and male Dorper sheep as the sire breed. Thebreeding program was designed in such a way that it involveda nucleus for each indigenous breeds considered for the cross-breeding program. This ensured the continuous supply of theDorper breed to Breed Evaluation and Distribution (BED)sites and distribution of F1 crossbreds to farmers. HaramayaUniversity has one of these BED sites. The university isstrategically located in the eastern part of the country whereBlackhead Ogaden and Hararghe Highland sheep breedsdominate. So far, over 275 crossbred lambs have been bornat the university farm. A previous study demonstrated im-proved post-weaning growth performance and carcass traitsof crossbreds (Dorper × indigenous) under controlled on-station management (Tsegay et al. 2013). However, there isno information on pre-weaning growth performance of thecrossbred lambs. On-station evaluation of pre-weaninggrowth performance traits is crucial since it is an indicator ofthe performance of the breeds. Therefore, the objective of thisstudy was to assess the effect of genetic and non-geneticfactors on pre-weaning growth performance of crossbredlambs (75 % Dorper 25 % indigenous lambs; and 50 %Dorper 50 % indigenous lambs) under semi-intensive hus-bandry practices in eastern Ethiopia.

Materials and methods

Location of the study area

The study was conducted at Haramaya University SheepFarm. The University is located 515 km east of AddisAbaba at 9° N and 42° E. The site is situated at 1,950 m abovesea level and has a mean annual rainfall of 790 mm and amean annual temperature of 16 °C. The pattern of rainfall isbimodal, consisting of a short rainy season covering fromApril to June and main rainy season from July to October,while the remaining months are considered as dry season(Mishira et al. 2004).

Breeding and husbandry practice of sheep

The sheep crossbreeding program at Haramaya was started in2008 by using DR sheep as a sire breed and indigenous BHOand HH as dam breeds. The average body weight and age ofDR sire breed at the time of mating were 58.3 kg and 2 years,respectively, while the average body weight of BHO and HHewes were 21.5 and 22.0 kg, respectively. Moreover, theaverage body weight of crossbred ewes (50 % DR and 50 %BHO) was 39.6 and 36.0 kg for 50 % DR and 50 % HH ewes.The breeding (mating) method employed was natural matingusing Dorper rams. Ewes (Hararghe Highland and BlackheadOgaden) were purchased from Chelenko and Jijiga openmarkets, respectively. The age of indigenous ewes at matingwas 18 months. Crossbred ewes and breeding rams wereobtained from the university farm. The age of crossbred ewesat the time of mating was 14 months. During the matingperiod, four Dorper sires per year were stratified into matinggroups randomly and the mating period lasted 30–42 days.The average ratio of males to females was 1:20. Ewes weremated for 30–42 days once a year to lambs during the rainyseason to take advantage of available grazing during thisseason.

The house was cleaned and disinfected prior to arrival ofsheep (foundation stock) and cleaned every day thereafter.Upon arrival at the university, sheep were drenched with abroad-spectrum anthelmintic albendazole (Albenda-QK300 mg) administered as one bolus per 30-kg body weightagainst internal parasites, sprayed with acaricides (vetazinon60 % EC 600 g/l) administered as 1 ml of vetazinon to 1 L ofwater against external parasites, and vaccinated forpasteurellosis using ovine pasteurellosis vaccine and anthraxusing anthrax vaccine. During the mating period, ewes wereallowed to graze for 8 h a day in an open natural pasture. It iscomposed of dominant pasture types consisting ofHyparrhenia species, Cynodon dactylon , Sporobolusafricanus , and Pennisetum species with average crude proteincontent of 7.7 %. In addition to grazing, ewes were supple-mented with 200 g of concentrate mix at the morning(8:30 a.m.) and afternoon (2:30 p.m.). The mix consisted of66%wheat bran (18.7 % crude protein), 33% noug seed cake(Guizotia abyssinica ; 35 % crude protein) and 1 % table saltper head per day and fed in group. Similarly, during the matingperiod, rams were allowed to run with ewes in an open naturalpasture and fed with concentrate mix and salt in a group.Water was provided to the animals three times per day andthey were allowed to drink as much as they wanted. Duringthe night, rams were separated from the mating group andhoused together.

During early pregnancy, ewes were grazing on naturalpasture without supplementation similar to dry ewes.However, starting from 4 months of pregnancy, ewes receivedthe same amount of supplement as that of ewes during the

456 Trop Anim Health Prod (2014) 46:455–460

mating period. During the late pregnancy towards the lambingperiod, ewes grazed around the barn and were housed sepa-rately in parturition pens (1×1-m dimension) to avoid thepossible trampling of the new born lamb and to create a firmrelationship between the new born lamb and the dam.

During the pre-weaning growth period, lambs wereallowed to suckle their dams up to 4 months of age, followingthe practices of the farm. Special consideration was given fororphan lambs that lost their dams, in which case cow's milkwas provided until weaning. Also, depending upon the milkyield of the ewes, some lambs were given additional 30 ml ofcow milk every day after birth until weaning. However, thesemilk-supplemented lambs were not included in the analysisfor the growth performance study. Lambs usually startedgrazing at the age of 2–3 weeks and were supplemented withconcentrate mix together with their dams from 2 months ofage. Weaning lambs were mainly kept and grazed on thepaddock inside the enclosed area of the farm together withtheir mothers. However, when conditions allowed, such aswhen the grazing area is not far from the sheep house, lambswere allowed to graze with their dams. After weaning, lambsconstantly leave to the field outside the enclosed area to grazeon natural pasture and supplemented with 200 g of concen-trate mix. Genetic groups of crossbred lambs evaluated in thisstudy were ¾DR¼HH, ¾DR¼BHO, ½DR½HH, and½DR½BHO.

Data collection

Data were collected from the records of Haramaya UniversitySheep Improvement Farm. The data consisted of growthrecords of 275 crossbreeds of Dorper × Hararghe Highlandand Dorper × Blackhead Ogaden lambs born from 2009 to2011. Birth date, birth weight, weaning weight, genetic groupor breed of lambs, and non-genetic factors like litter size,gender of lamb, and parity of dam were recorded for eachlamb during this period. Body weights of lambs were mea-sured using weighing balance. Body weights of lambs record-ed at 4 months was considered as weaning weights, while theweight recorded during 24 h after birth was taken as birthweights. Pre-weaning average daily gain was estimated as thedifference between 4 months weight and birth weight dividedby the time interval in days.

Data analysis

Data on pre-weaning growth performance were analyzedusing the general linear model procedure of SAS (2003).The model considered fixed effects of lamb breed, type ofbirth, parity, year of birth, season of birth and sex of lambs.Two-way interactions were not significant for most variablesand hence removed from the analysis. Tukey's adjustment wasused to compare means.

The statistical model employed was

yijklmn ¼ μþ bi þ l j þ pk þ sl þ gm þ yn þ eijklmno

Where:

μ the overall meany ijklmn pre-weaning growth traits (birth weight, weaning

weight, pre-weaning average daily gain)b i fixed effect of the i th lamb breed (i =1, .... 0.4)l j fixed effect of the j th type of birth (single, twin)pk fixed effect of the k th parity (k =1, 2, 3, 4)s l fixed effect of the l th season of birth (main rainy

season, dry, and short rainy)gm fixed effect of the m th sex (male, female)yn fixed effect of the n th lambing year (2009,… 2011)e ijlkmno random error and was assumed as NID (0, σe2)

Results and discussion

Pre-weaning growth performance of crossbred lambs

Least square mean birth weight, weaning weight and averagedaily gain ranged from 2.9, 14.9, and 99.2 kg in ½DR½HH to3.1, 20.7, and 147.2 in ¾DR¼BHO (Table 1). The meanminimum birth weight, weaning weight, and average dailygain were recorded for all crossbreds with 50 % DR. Birthweight was ranged from 1 to 4.5 kg and it was wide forcrossbred lambs born to 50 % genetic inheritance. Weaningweight and average daily gain for 50 % crossbred lambsranged from 9.5 to 30 kg and 50.0 to 212.5 g, respectively,where the range was wider for crossbreds from BHOthan for HH. This could be due to the difference between thetwo indigenous dam breeds since HH are an early maturingbreed compared to BHO (Tsegay et al. 2013). However,weaning weight and average daily gain ranged from 12 to30 kg and 79.1 to 212.5 g, respectively, for 75 % DR inheritedbut the range was wider for crossbreds from HH than fromBHO.

Generally, the distribution showed that there were hugevariations between minimum and maximum values for allpre-weaning growth performance variables. This could beattributed to difference in genetic and non-genetic factors(e.g., breed, body condition of ewes, parity, season of birth,sex of lambs, and year of birth).

Effect of breed

Pre-weaning growth performance of crossbred lambs born toDR as a sire breed and the two indigenous sheep breeds (BHOand HH) as a dam breed were different (P <0.01) (Table 2).

Trop Anim Health Prod (2014) 46:455–460 457

Birth weight was generally higher (P <0.01) for the crossbredsborn to 75%Dorper sire breed than 50%Dorper sire, with theexception of 50 % BHO, which had comparable weight.Crossbred lambs born to 75 % Dorper sire were heavier(P <0.01) at birth than crossbred lambs born to 50 %HH but similar to 50 % BHO. Thus, crossbred lambs with ahigh level of Dorper inheritance were heavier at birth thanlambs having a low level of Dorper inheritance. This could beattributed to the inherited faster growth of the sire breed.However, crossbreds born to 50 % BHO and 50 % HH hadthe same birth weight. In addition, similar (P >0.05) birthweights were also noted between crossbred lambs of 75 %Dorper and 25 % BHO and 75 % Dorper and 25 % HH.

There was a significant difference (P <0.01) in weaningweight and average daily gain among the different breed

groups compared (Table 2). Both weaning weight and averagedaily gain were higher (P <0.05) for crossbreds born to 75 %Dorper sire than 50 % Dorper sire. However, there was nodifference in weaning weight and average daily gain between50 % BHO and 50 % HH. Crossbred lambs born to 75 %Dorper sire breed had heavier (P <0.01) weaning and averagedaily weight gain than crossbred lambs born to 50 % HH and50 % BHO. This is attributed to the higher performance ofDorper sire breed than dam breed. This was also reported byFourie et al. (2009) who reported that Dorper lambs achievedhigher weaning weight and average pre-weaning growth un-der vastly different environmental conditions. Similarly,crossbreds of Dorper and Pelibüey breed sheep have shownimproved weaning weight compared to the pure breeds(Canton et al. 2009). However, in the current study, weaning

Table 1 Descriptive statistics ofbirth weight, weaning weight, andaverage daily gain of crossbredlambs

PADG pre-weaning average dailygain

Breed Parameters Number Mean Minimum Maximum

½DR½BHO Birth weight (kg) 107 3.0±0.1 1.0 4.5

Weaning weight (kg) 104 15.1±0.3 9.5 30

PADG (g/day) 104 100.4±2.6 50.0 212.5

½DR½HH Birth weight (kg) 103 2.9±0.1 1.0 4.5

Weaning weight (kg) 97 14.9±0.1 9.5 20

PADG (g/day) 97 99.2±2.2 50.0 150.0

¾DR¼BHO Birth weight (kg) 28 3.1±0.1 2.5 3.5

Weaning weight (kg) 26 20.7±1.1 16.0 25

PADG (g/day) 26 147.2±8.0 112.5 179.1

¾DR¼HH Birth weight (kg) 37 3.1±0.2 1.5 4.5

Weaning weight (kg) 35 19.2±1.1 12.0 30

PADG (g/day) 35 134.2±8.9 79.1 212.5

Table 2 Least square means (± SEM) for effects of breed, litter size, and parity on pre-weaning growth traits of crossbred lambs

Parameters Birth weight (kg) Number Weaning weight (kg) Number PADG (g/day) Number

Breed ** ** **

½DR½BHO 3.0±0.1ab 107 15.1±0.3b 104 100.4±2.6b 104

½DR½HH 2.9±0.1b 103 14.9±0.1b 97 99.2±2.2b 97

¾DR¼ BHO 3.1±0.1a 28 20.7±1.1a 26 147.2±8.0a 26

¾DR¼HH 3.1±0.2a 37 19.2±1.1a 35 134.2±8.9a 35

Litter size * N * N ** N

Single 3.0±0.0a 261 17.6±1.5 a 250 122. 4±1.8 a 250

Twin 2.87±0.24b 14 15.4±0.2 b 12 103.1±12.2 b 12

Parity * N * N ** N

1 2.9±0.0b 112 12.4±0.6c 104 75.0±2.9c 104

2 3.1±0.1ab 101 15.8±0.3a 97 105.5±2.5ab 97

3 3.2±0.1a 48 15.9±0.5a 48 107.6±4.1a 48

4 3.4±0.3a 14 14.9±1.7b 13 99.3±14.8b 13

Least squares means with different superscript in the same column for the same parameter are significantly different

N number of observation; PADG pre-weaning average daily gain

*P<0.05

**P<0.01

458 Trop Anim Health Prod (2014) 46:455–460

weight (P >0.05) and average daily gain were similar (P >0.05) between 75 % BHO and HH as well as between 50 %HH and 50 % BHO.

Effect of litter size and parity

Litter size had significant effect on birth weight, weaningweight (P <0.05) and average daily weight gain (P <0.01) ofDorper × indigenous sheep crossbred lambs (Table 2).Accordingly, crossbred lambs born as singles had heavierbirth weight than twins. This could be attributed to greaterintra-uterine nutritional and space competition in twin bornlambs compared with that of single-born lambs. Supportingthis hypothesis, Robinson et al. (1977) reported that as thenumber of fetuses increase, the number of caruncles attachedto each fetus decreases, thus reducing the feed supply to thefetus and hence reducing the birth weight of the lambs.

Heavier weaning weight and pre-weaning average dailygain were also noted in lambs born as singles compared withthose born as twins. The higher daily weight gains attained insingle-born lambs could be due to relatively higher amount ofmilk consumed per lamb as there was no competition forewe's milk. However, twins and triplets had lighter averagebirth weights and were more subject to physiological starva-tion after birth due to competition. To improve weight gain intwin born lambs, a special feeding system, such as creepfeeding may be required. The finding of this study is inagreement with other studies (Berhanu and Aynalem 2009;Abd-Allah et al. 2012).

Parity of the ewe had also influenced birth weight (P <0.05), weaning weight and average daily gain (P <0.01) incrossbred lambs. In general, there was an increasing trend inthe birth weight of lambs as the parity of ewes advances from

the first to fourth (Table 2). Lambs born from ewes in theirfirst parity were lighter (P <0.05) than lambs born from laterparities (third and fourth). This might be attributed to the factthat first-parity ewes are still growing and thus must partitionnutrients for their own growth in addition to the fetal demand.It is generally known that mothering ability, especially milkproduction, increases with parity; older ewes are larger inbody size and are better milk producers (Stobart et al. 1986).Similar results were documented by previous studies(Berhanu and Aynalem 2009). Weaning weight and pre-weaning average daily gain were relatively higher (P <0.01)in parity three followed by parity two and lower in paritiesfour and one. The same result was demonstrated by Hussainet al. (1996) who found that weight increases at least up tothird parity. The likely reason for the decline of pre-weaningdaily weight gain of lambs as the parity of their dams ad-vanced beyond parity three might be related to a reduction inmilk production performance of their dams.

Effect of sex

There was significant (P <0.05) variation between male andfemale lambs in pre-weaning growth performance traits ex-cept pre-weaning average daily gain of crossbred lambs(Table 3). This is a physiological mechanism that male ani-mals do have a faster growth rate and are heavier at similarages than females. Accordingly, male lambs had better (P <0.05) pre-weaning growth performance than their femalecounterparts. This study was supported by previous findingswhere male lambs had higher weights at 60, 120, 180, and240 days and daily weight gain than females (Berhanu andAynalem 2009). Furthermore, male lambs were heavier thanfemale ones at birth (Yaqoob et al. 2004). The larger weight of

Table 3 Least square means (± SEM) for effects of season, sex, and year on pre-weaning growth traits

Parameters Birth weight (kg) Number Weaning weight (kg) Number PADG (g/day) Number

Sex * * NS

Male 3.15±0.06a 144 15.78±0.27a 137 105.26±2.31 137

Female 2.88±0.06b 131 15.02±0.33b 125 102.00±2.69 125

Season of birth ** N ** N ** N

Main rainy 3.27±0.09a 53 17.35±0.62a 50 117.31±5.21a 50

Dry 2.85±0.08b 79 14.46±0.36b 72 94.19±2.96b 72

Short rainy 3.15±0.07a 143 15.32±0.27ab 140 103.92±2.17ab 140

Year of birth ** N ** N ** N

2009 2.73±0.06b 105 13.78±0.34b 98 92.04±2.82b 98

2010 3.0±0.07ab 103 16.22±0.27a 99 110.15±2.45a 99

2011 3.49±0.09a 67 16.94±0.48a 65 112.07±3.9a 65

Least squares means with different superscript in the same column for the same parameter are significantly different

NS not significant; N number of observation; PADG pre-weaning average daily gain

*P<0.05

**P<0.01

Trop Anim Health Prod (2014) 46:455–460 459

males compared to female at 6 months of age could be due tohormonal differences in their endocrinological and physiolog-ical functions (Ebangi et al. 1996). However, no significantdifference on birth weight, weaning weight, and daily weightgain were noted between male and female lambs by Abd-Allah et al. (2012).

Effect of season and year

Season and year of birth showed consistent effects (P <0.01)on birth weight, weaning weight, and pre-weaning growthrates (Table 3). Lambs born during the main rainy season(P <0.01) had higher weaning weight and average dailyweight gains as compared to lambs born in the dry season,but similar to those born in short rainy season. This could beassociated with variation in nutritional management. In con-trast to this study, Berhanu and Aynalem (2009) reportedheavier birth and 120 days weight in lambs born in the dryseason as compared to those born in the wet season. Abd-Allah et al. (2012) also found no significant variation on thetraits between the wet and winter seasons.

Regarding the effect of year of birth on pre-weaninggrowth variables, the general trend showed that lambs bornduring the later years had heavier pre-weaning growth traits ascompared to lambs born in earlier years. Accordingly, lambsborn in 2011 were heaviest (P <0.01), had the highestweaning weight, and pre-weaning live weight gains followedby those born in 2010. The lowest pre-weaning growth per-formance was noted for lambs born in 2009. This could be theresult of improvement in feed availability, managementmethods, body condition of dams, and farm manager's skillsover successive years. In agreement with this study, Berhanuand Aynalem (2009) reported a significant effect of year ofbirth on lamb weights at 60, 120, and 180 days. However,Abd-Allah et al. (2012) reported a non-significant effect ofyear on birth weight and pre-weaning growth performance.

Conclusion

This study demonstrated that pre-weaning growth perfor-mance of indigenous sheep breeds were improved as the levelof Dorper inheritance increased from 50 to 75 %. The resultconfirmed that environmental factors have contributed to var-iation on pre-weaning growth traits. The pre-weaning perfor-mance of crossbred lambs improved with increase in maternalparity until it either didn't change (in case of birth weight) ordeclined in case of weaning weight and average daily gainafter parity three. Pre-weaning growth performance of single-born and male lambs was considerably better than their twinand female counterparts, respectively. This study also support-ed the practice of culling ewes older than fourth parity aslambs born from these groups of dams tends to be inferior.

Therefore, it can be concluded that upgrading the geneticmakeup of indigenous sheep breeds up to 75 % of Dorperinheritance improved pre-weaning growth performance of theindigenous breeds under semi-intensive management inEthiopia.

Acknowledgments The Ethiopian Sheep and Goat Productivity Im-provement Program funded by USAID and Haramaya University areduly acknowledged in allowing access to the data records of the farm.

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