Mini review: breeding Awassi and Assaf sheep for diverse management conditions

The Local Awassi, a triple-purpose breed for meat, milk, and carpet–wool production, is a low-prolific, hardy breed that is well adapted to the unfavorable conditions of the Middle East, where it is managed under traditionally extensive to semi-extensive conditions. Breeding work with the Awassi has included within-breed selection, crossbreeding, and gene introgression. Those efforts resulted in a variety of Awassi-derived genotypes that successfully occupy semi-intensive as well as intensive production systems. Thus, within-breed selection resulted in development of the “Improved Awassi”—a dairy-type Awassi strain which, under intensive management, produces over 500 l milk/ewe annually; crossbreeding with the East Friesian breed led to the development of the Assaf dairy breed, which exceeds the Improved Awassi in prolificacy and in year-round breeding activity, and introgression of the B allele of the FecB locus into the Awassi and Assaf breeds resulted in the formation of the prolific Afec Awassi and Afec Assaf strains, with prolificacies of 1.9 and 2.5 lambs born per ewe lambing, respectively. Advanced molecular genetics tools have enabled a better understanding of how the Awassi breed was formed during domestication and have uncovered differences in its genetic structure compared to other breeds. Implementing large-scale selection schemes that implement emerging new information on the sheep genome, overcoming threats of inbreeding depression, and further breeding for high uterine capacity are the new breeding goals for the Awassi, Assaf, and their derivatives.     

Alternative feedstuffs and their effects on performance of Awassi sheep: a review

Fat-tailed sheep (FTS) is a group of breeds characterized by large (fatty) tails that it is commonly distributed in Africa, Middle East, Pakistan, and to a lesser extent in other countries. Awassi, a common FTS breed in many Mediterranean countries, is adaptive and suitable to live in harsh conditions of the arid and semiarid areas. One of the main constraints for sheep industry in those areas is the limited supply and variable quality and quantity of feedstuffs. Using several alternative feedstuffs (AF) has been a common practice to decrease production cost of Awassi sheep industry in those areas. The appropriate AF to be used is determined by several animal and feed factors. These AF includes, but not limited to, unconventional feedstuffs, agricultural byproducts, and agro-industrial byproducts. A good body of literature about the use of AF and the effects of such use on performance of Awassi sheep is available. Some of these AF have been shown to be safely used in Awassi diets with no detrimental effects on sheep performance or health and, thus, recommended to lower the production cost. Other AF has controversial effects and recommendations. This paper reviews the effects of using AF on performance of Awassi ewes and lambs. Effects on intake, nutrient digestibilities, growth rate, and carcass characteristics of lambs and on intake, nutrient digestibilities, body weight change, milk yield, and milk composition of ewes will be emphasized. Recommendations and limitations for using AF will also be briefly discussed.     

Evaluation of Awassi genotypes for improved milk production in Syria

A performance evaluation, conducted between 2003 and 2005, compared the milk production of three genotypes of Awassi ewes: Turkish (T), Syrian (S) and the F1-cross between the Turkish and Syrian ewes (TS), at the International Center for Agricultural Research in the Dry Areas (ICARDA) experimental farm in Tel Hadya (northern Syria). After weaning, which occurred at 56days, milk yield and milking length were measured weekly during the milking period (n = 381). Milk yield of TS and T ewes were 12% and 30% higher, respectively, than S ewes. Milk yield and milking length of TS ewes reflected additive inheritance and did not differ from the parental genotypes' average (p ≥ 0.199). Culling of low producing ewes in 2003 and 2004 also resulted in increased milk yield. Dams of all genotypes displayed similar weights at birth (p = 0.898) and weaning (p ≥ 0.677). The latter suggests dams of the different genotypes olerated equally the pre-weaning lactation load. Performance tended to improve as ewes aged, with milk yield and milking length peaking at 3years of age (p > 0.05). Ewe lambing weight, birth–weaning ewe weight decline, litter size, and litter weight weaned peaked at 4–5years of age (p ≤ 0.016). With the exception of birth–weaning ewe weight decline, year effects influenced the traits under study (p ≤ 0.035). Excluding litter size, the best performance was in 2005, followed by 2003 and 2004. Milk yield increased with litter size at weaning (b = 18.7; p = 0.024). The lambing–weaning ewe weight decline (3.6kg) and ewe productivity (0.46kg litter weaned weight per kg ewe weight) did not differ between genotypes (p ≥ 0.178). Average litter size was 1.15, with the TS ewes displaying the largest litter size (1.23; p = 0.026). Single lambs were 25% heavier than twins at birth averaging 4.73kg and 3.8kg, respectively. Male lambs were 4% heavier than female lambs at birth (p < 0.0001) and 9.3% heavier at weaning (p < 0.0001). Lamb birth weights, weaning weights and daily weight gains were similar for all genotypes (p ≥ 0.210). The average proportion of fat (5.95%), crude protein (5.19%) and solids non-fat (11.29%) in the milk varied across genotypes where S < TS < T (p ≤ 0.0037). F1 crosses with T increased the productivity of S ewes by 12.2%. It is noteworthy that this occurred under improved feeding and may not be recommended for other conditions. Culling low producing ewes led to a 12.8% increase in milk yield, which could translate into a substantial boost in revenue for farmers rearing traditional sheep flocks in milk producing areas.     

Foetal anasarca in Awassi sheep

Two anasarcous foetuses of Awassi sheep are described. The foetuses were removed from the dams by caesarean section because of dystocia due to failure of cervical dilation. Uterine incision was made in situ because uteri were so distended they could not be brought out from the site of incision. Large quantities of uterine fluids and abnormal thick placentas were found. One foetus weighed about 7 kg and the other 13 kg. The foetal heads were deformed: the upper jaw was prognathic and the left ear of the small foetus was cystic. Necropsy revealed subcutaneous musculature was soft and flabby and abdominal and thoracic cavities contained serosanguinous fluid. Histopathological examination revealed that only the larger foetus had focal aggregates of basophilic nucleated red blood cells and scattered megakaryocytes in the liver. We conclude that anasarca can occur in Awassi sheep, with and without associated extramedullary haematopoiesis.     

Tropical milk production systems and milk quality: a review

We reviewed information on dairy cattle production systems in the tropics, the factors involved, and their influence on milk composition. Genetic factors had greater influence on milk production; specialized breeds produced more milk, and there was an inverse relation between the content of fat, protein, total solids, and the amount of milk produced. Season was related to the availability of forage, and the type of grazing system. Greater pasture area increased individual production, while a greater supply of feed concentrate did not increase milk production. The number of calvings positively affected milk production through the fifth calving, with subsequent declines in production. Milk production increased to a maximum and then declined as lactation progressed. Specialized systems had higher production and better hygienic milk quality; milking and container equipment are critical for maintaining milk sanitary quality. Factor interaction is highly complex, preventing the generation of specific recommendations and general principles applicable to the specific conditions for each system.

     

A review of morphological characteristics relating to the production and reproduction of fat-tailed sheep breeds

The purpose of this study is to survey the literature pertinent to some morphological traits which are related with the production and reproduction of fat-tailed sheep breeds. The fat-tailed breeds were identified according to Food and Agriculture Organization databases. Articles referring to all these sheep breeds were evaluated. The morphology of udders and their measurable variables were collected and described. The particularities of pelt and fleece features which are important from an economic point of view were summarized. Linear, planar, and spatial parameters of body, slaughter, and carcass factors were compared at various ages of breeding. Testicular dimensions and semen characteristics were recorded. Their relationships with productive and reproductive performance were discussed. The pattern of ovarian follicle development and the involution of the genital tract were assessed from the anatomical point of view in normal and untreated animals. The data presented here provide useful baseline information on the normal morphological aspects which are important in the animal production of these breeds.     

Serosurvey on theileriosis in Awassi sheep in Syria

A serological survey using indirect fluorescent antibody test (IFAT) for Theileria spp. infection of sheep has been carried out from 1994 to 1997 in the provinces Daraa, Hama, Homs and Latakia in Syria. The results revealed a mean seroprevalence of 59.9% without significant differences between years (p = 0.57) and provinces (p = 0.126).     

Computer modeling of sheep reproduction: II. Accelerated reproduction in sheep

A computer simulation program was written in SLAM (Simulation Language for Alternative Modeling) to simulate certain biological aspects involved in alternative systems of reproduction in sheep. Four fundamental lambing schemes, once a year, three times in 2 yr, twice a year and continuous schemes, along with modifications of these schemes, are simulated. Parameters of greatest effect in this simulation were the average spread of the estrous season (SA), the measure of asymmetry (SD) and the maximum proportion of ewes exhibiting estrus (MX). It was demonstrated that the greater the SA values (longer estrous seasons and shorter anestrous seasons), the more advantageous it was to breed frequently. The SD and MX parameters influenced to a lesser degree the lambing results obtained from these simulations. The relative merits of certain breeds and locations for out-of-season breeding were studied and evaluated for annual and seasonal fertility.     

Peritoneal fluid analysis in adult, nonpregnant Awassi sheep

BACKGROUND: To the authors' knowledge, there is no information in the literature about normal peritoneal fluid values in ovine species. OBJECTIVES: The purpose of the study reported here was to establish reference intervals for peritoneal fluid from clinically normal Awassi sheep and to compare the values to those in blood. METHODS: Peritoneal fluid and blood samples were collected into tubes containing EDTA, from 40 clinically healthy, nonpregnant, female Awassi sheep, aged 2 to 7 years. Total nucleated cell count (TNCC) was determined using an electronic cell counter. Total protein, albumin, urea, creatinine, and glucose concentrations and aspartate transaminase activity were analyzed using commercially available kits. RESULTS: TNCC (mean +/- SD) of peritoneal fluid was 1.1 +/- 0.87 X 10(3)/microl, with neutrophils (3.9%), lymphocytes (33.5%), macrophages/monocytes (61.2%), and eosinophils (1.4%). Biochemical results in peritoneal fluid were: total protein, 1.7 +/- 0.74 g/dL; albumin, 1.0 +/- 0.04 g/dL; urea, 12.6 +/- 3.95 mg/dL; creatinine, 0.6 +/- 0.19 mg/dL; glucose, 54.8 +/- 6.11 mg/dL; and aspartate transaminase, 23.5 +/- 8.82 U/L. Eosinophil percentage and creatinine concentration did not differ significantly from blood values. CONCLUSION: Baseline values for cytologic and biochemical parameters in peritoneal fluid of Awassi sheep, with comparison to blood, have been generated. Such data may be applicable to other ovine species and can be used in the clinical investigation of ovine abdominal disorders.     

Epidemiology of gastrointestinal parasites of Awassi sheep in Iraq

Studies on the epidemiology of gastrointestinal nematodes of sheep, conducted at two different farms in the Baghdad area, in 1979, revealed two peaks in worm egg counts in ewes, one in spring and the other in autumn; the latter coincided with the lambing season. Similarly in lambs, two peaks of infection were apparent, but the spring peak was not so well defined. During the hot and dry summer months of Iraq, helminthic infection was at a low level. Faecal culture for larvae and their identification indicated the predominance of Haemonchus contortus infection in the ewes and that of Ostertagia and Trichostrongylus spp. in the lambs examined, Trichostrongylus infection predominating during the hot, dry period of the year. The self-cure phenomenon as well as preparturient rise in egg counts, as reported in other countries, was also observed during this study.     

Epidemiology of ovine brucellosis in Awassi sheep in Northern Jordan

We used a combined cross-sectional and longitudinal design to estimate seroprevalence of Brucella antibodies in Awassi sheep and the incidence of abortion due to brucellosis during one lambing season, and to test risk factors. The Brucella organisms isolated from aborted fetuses and vaginal swabs were characterized as Brucella melitensis biotype 3. Seventy Awassi sheep flocks were selected randomly from Northern Jordan. Sixty two of the 70 flocks were used in the cross-sectional study and 8 flocks were monitored for three consecutive months to estimate the incidence of abortion. Questionnaire data and 602 serum samples were collected and analyzed. Thirty five flocks (56%) were brucellosis-seropositive by the Rose Bengal plate-agglutination test (RBT) and 28 (45%) by enzyme-linked immunosorbent assay (ELISA). The crude seroprevalence of brucellosis at the individual-animal level was 14.3% by RBT, 7.2% by ELISA and 2.2% using both tests in series. The flock-specific, animal-level abortion risk ranged between 2.5 and 50% (median=22.6%). The flock brucellosis-status was used as the outcome variable in a multivariable logistic regression. Grazing at communal pasture increased odds, but usage of disinfectants, previous vaccination for brucellosis, and tap water were protective. The animal-level incidence of abortion was 20% and the specific incidence risk of abortion due to brucellosis was 13%.     

Effect of treatment with netobimin on milk production of sheep

In the Basque country lambing takes place during winter, followed by milking until late spring or summer, so it was considered that this would be the most profitable period for deworming, when there was an increased production pressure on ewes with depressed immune status owing to the peri-parturient relaxation of immunity. The drug employed was netobimin, and the trial was carried out in 22 commercial flocks, in each of which ewes were allocated to one of three similar groups. One group was left as a non-treated control (T0), the second was dosed 15 days before parturition (T1), and the remaining group dosed both at 15 days before and 15 days after lambing (T2). Mean total milk production in the T2 group increased by 8.8 and 6.3% in the second and third month post-partum, respectively, compared with that of the controls (T0), while over the standard lactation period of 120 days the T2 group showed a significant (8.9%) increase in production compared with the controls. The T1 group did not significantly differ from T0. The market value of the increase in milk production was calculated to be approximately 700% of the cost of treatment with netobimin.     

Genotype effects of milk protein polymorphisms on milk production in East Friesian dairy sheep

The frequencies of milk protein variants alphas1-casein, alphas2-casein, beta-casein and beta-lactoglobulin were determined in 182 milk sheep from 7 flocks in Lower Saxony and Saxony. The genotype effects of these polymorphic milk protein variants on milk performance traits were estimated for 173 ewes using a test day model with fixed regression.The model included the fixed effects of colour variant of the breed, region, lambing season, lambing year, lactation number and number of lambs born. The herd and animal effect were treated as random and the days in milk as linear and non-linear covariates. The milk protein variants of alphas1-casein and beta-casein showed a significant relationship to protein content and the variants of beta-casein to milk fat content. Milk fat yield was significantly associated with the milk protein variants of alphas2-casein, whereas the other milk performance traits were not significantly correlated.     

The response of Awassi and Merino sheep to primary infection with Haemonchus contortus

The possible existence of breed differences in the response of sheep to primary infection with Haemonchus contortus was examined by comparing worm establishment and pathogenic effects of the parasite in Awassi and Merino sheep of haemoglobin type B infected with 500 third stage H. contortus larvae per kg body weight. The results showed that the Merino sheep had lower faecal egg counts and worm burdens and suffered less severe clinical disturbances than sheep of the Awassi breed. This suggests that genetic resistance operates primarily at the level of worm establishment.     

Serological studies on prevalence of Toxoplasma gondii in Awassi sheep in Syria

Survey was conducted in 9 Syrian provinces on clinically healthy Awassi sheep. Serum samples were collected from several districts (more than 47 localities--31 villages and 20 herds). Animals were 1-5 years old. 458 samples were collected in spring 1997 and 352 samples were collected from November 1998 through February 1999. The result indicated that seroprevalence of Toxoplasma gondii ranged between 0-100% in the herds and 13.8-74.5% between the provinces. And the mean of sero-prevalence was 44.56% in all provinces. The following prevalence were found in as indicated: Idleb 74.46%, Hama 72.16%, Deraa 63.35%, Al-Hssakeh 51.11%, Suweida 46.98%, Homs 40%, area of Damascus 23.48%, Aleppo 17.02% and Deir Ezzor 13.79%. The serological titer was 1:4 for 37.67% to 1:64 for 78.93% of the positive samples. Results showed that there are 29 (8%) of the positive samples with 1:1.000, and only 5 (1.38%) with 1:4.000. It is concluded that the Toxoplasma-infections may be one of the main causes of sheep abortions and as the source of human infection in Syria. Therefore, it is suggested that further epidemical studies are needed.     

Effect of anthelmintic treatment on the performance of Awassi sheep in Iraq

Studies are reported on the effect of anthelmintic treatment on the body weight gain and wool growth of ewes with subclinical helminth infections. The parasites involved were Fasciola gigantica and Ostertagia spp., together with some Haemonchus contortus, Trichostrongylus spp., and Dictyocaulus filaria. In 1 group, 5 sheep, which were treated twice with tetramisole at an interval of 4 weeks to remove gastro-intestinal nematodes and lungworms, showed an increase of 41% in weight gain and 3.2% in wool growth compared with an untreated group. Another group, which was treated with both tetramisole and rafoxanide to remove nematode and fluke infections, had a 143% increase in weight gain and 81% in wool growth compared with the control.     

Relationship between inbreeding and milk production traits in two Italian dairy sheep breeds

The effects of inbreeding in livestock species breeds have been well documented and they have a negative impact on profitability. The objective of this study was to evaluate the levels of inbreeding in Sarda (SAR, n = 785) and Valle del Belice (VdB, n = 473) dairy sheep breeds and their impact on milk production traits. Two inbreeding coefficients (F) were estimated: using pedigree (F_PED), or runs of homozygosity (ROH; F_ROH) at different minimum ROH lengths and different ROH classes. After the quality control, 38,779 single nucleotide polymorphisms remained for further analyses. A mixed-linear model was used to evaluate the impact of inbreeding coefficients on production traits within each breed. VdB showed higher inbreeding coefficients compared to SAR, with both breeds showing lower estimates as the minimum ROH length increased. Significant inbreeding depression was found only for milk yield, with a loss of around 7 g/day (for SAR) and 9 g/day (VdB) for a 1% increase of F_ROH. The present study confirms how the use of genomic information can be used to manage intra-breed diversity and to calculate the effects of inbreeding on phenotypic traits.