Assaf Sheep Research Articles

Genetic relationships between Spanish Assaf (Assaf.E) and Spanish native dairy sheep breeds

At present, the Assaf is the main dairy sheep in Spain. The Spanish Assaf (Assaf.E) was formed by male-mediated absorption of native Spanish sheep. Here we assess the genetic relationships among the Assaf.E and major native Spanish dairy breeds using microsatellites to contribute to the knowledge of the formation and within-population genetic variability of the breed. Blood samples from 44 unrelated Assaf.E individuals from 23 different Assaf.E flocks spread throughout 6 different Spanish provinces were obtained and genotyped using 14 microsatellites. Up to 312 additional samples belonging to the Awassi and Milchschaf sheep breeds and to six native Spanish dairy sheep breeds (Castellana, Churra, Latxa, Manchega, and Rubia de El Molar) as well as samples from Merino individuals to be used as the outgroup were also analysed observed ( H o) and expected ( H e) heterozygosity, rarefacted number of alleles per locus and distances based on molecular coancestry information were computed. Probabilities of assignment of the Assaf.E individuals to native Spanish dairy sheep breeds and cryptic genetic structure in the whole dataset were also assessed. It can be concluded that the Assaf.E breed has low genetic variability and high genetic distance with respect native Spanish dairy sheep breeds. From our results, the formation of the Assaf.E breed basically occurred via the absorption of individuals belonging to the Entrefino type, particularly to the Castellana and Manchega populations. Furthermore, Churra individuals may have participated in the formation of the Assaf.E breed at an early moment of the introduction of the breed into Spain.

Screening for polymorphism at the prion protein (PrP) locus ( PRNP) in Awassi and Assaf populations in Israel, the Palestinian Authority and Jordan

Screening for polymorphism at the prion protein (PrP) locus ( PRNP) was carried out in 33 flocks of Local Awassi (LA) sheep in Israel, the Palestinian Authority (PA) and Jordan. In addition, PRNP genotyping was carried out in two flocks of Improved Awassi (IA) in Israel and the PA and in 11 flocks of Assaf sheep in Israel. Most of the rams present in the flocks at the time of the survey 328, 44 and 298 rams from the LA, IA and Assaf breeds, respectively, were genotyped. The ARQ allele was found to be predominant in all three breeds with average frequencies of 0.74, 0.78 and 0.86 for the LA, IA and Assaf breeds, respectively. Frequencies of the desirable ARR allele in these breeds were 0.10, 0.05 and 0.06, respectively. ARH, AHQ and ARK alleles were identified at low/absent frequencies. Only one Assaf ewe carried the undesirable V allele at codon 136. A few scrapie outbreaks have been documented in the past in the region. To increase ARR allele frequencies in the Awassi and Assaf populations, distribution of homozygous ARR/ARR rams is recommended.

Prolificacy and lamb survival at birth in Awassi and Assaf sheep carrying the FecB (Booroola) mutation

Prolificacy up to the fifth parity and lamb survival at birth were investigated in ≥31/32 Awassi and ≥31/32 Assaf sheep belonging to the ++, B+ and BB genotypes at the FecB locus. In the Awassi, prolificacy of ++, B+ and BB ewes was 1.28, 1.90 and 1.92 lambs born/lambing (LB/L), respectively. In the Assaf, prolificacy of ++, B+ and BB ewes was 1.68, 2.40 and 2.55 LB/L, respectively. Lamb survival at birth in the ++ Awassi and the ++ Assaf averaged 0.98 and 0.94, respectively. It declined to 0.93 and 0.86, and 0.85 and 0.78 in the B+ and BB Awassi and B+ and BB Assaf, respectively. For singles, twins, triplets, quadruplets and quintuplets, lamb survival rate at birth was 0.98, 0.92, 0.86, 0.78 and 0.65, respectively. FecB genotype-litter size interactions were not significant ( P < 0.05). A compilation of study results in which prolificacy of the ++ and B+ genotypes at the FecB locus were investigated in a range of breed–environment combinations revealed that the B allele has a multiplicative effect on prolificacy as B+ prolificacy was significantly ( P < 0.05) linearly associated with ++ prolificacy.

Ovarian survival 6 years after whole organ cryopreservation and transplantation

It was previously reported (Arav et. al.2005) that ovarian function continued for up to 3 years after whole organ cryopreservation. Now we report the longest functional term survival (6 years) of autotransplanted frozen/thawed whole sheep ovaries. Descriptive research to perfect whole ovary cryopreservation/thawing procedures. Nine month old Assaf sheep were used for in vivo experiments (n = 3). Briefly, under general anesthesia one of the ovaries was excised leaving the contralateral in place. The ovarian artery was perfused with 10 ml of cold (4°C) UW supplemented with 10% DMSO for 3 minutes and then inserted into a glass freezing tube for cryopreservation. Unidirectional solidification freezing methodology reduced the temperature to –30°C at the very slow speed of 0.01 mm/sec, resulting in a cooling rate of −0.3°C/min after which the tubes were plunged into liquid nitrogen. Thawing was performed by placing the tubes into a 37°C water bath. Cryoprotectants were rinsed out from the thawed ovary via the ovarian artery using 10 ml Hepes-Talp medium supplemented with 0.5 M sucrose and 10 iu/ml heparin. Ovarian auto transplantation was performed by microscopic end-to-end vascular (artery and vein) reanastomoses to the contralateral ovarian vascular pedicle using 10–0 sutures at the same time that the intact ovary was removed. 6 years following transplantation sheep were sacrificed and the ovaries were excised, visually inspected, fixed in Bouin's liquid and embedded in paraffin for histology. Progesterone levels were measured in transplanted sheep up to 6 years post transplantation, twice per week indicating normal ovulation. Transplanted ovaries were of normal size and shape showing no necrotic lesions and one ovary clearly showed a recent corpus luteum. A total of 36 antral follicles were observed by transillumination and after sectioning, there were 4 GV's oocytes that matured in vitro to MII stage. Histological evaluation using Eosin & Hematoxylene revealed normal tissue architecture including follicles at various developmental stages and intact blood vessels. This report documents the longest term survival of whole ovary cryopreserved and then re-transplanted. Cryopreservation of whole ovaries using directional freezing and microvascular anastomoses is a promising method for preserving long-term reproductive capacity and endocrine function.

Dry-off treatment of Assaf sheep: Efficacy as a management tool for improving milk quantity and quality

Dry-off treatment of Assaf sheep by means of cow dry therapy tubes was tested. The sheep were treated 60 days before parturition by injection of a whole tube of cow dry treatment into each udder half. The sheep were tested for bacterial status before and after the treatment, to assess the success of the dry-off treatment, and were tested again at the end of colostrum milking to detect inhibiting substances in the milk. The treatment proved to be successful: bacterial infection decreased from about 60 to about 20%, and the somatic cell count in the bulk tank milk fell from about 2500 × 10 3 to less than 1000 × 10 3 cells mL −1. Concomitantly, the average milk production per ewe increased from 395 to 487 L year −1.

Estimate of milk and curd yield loss of sheep and goats with intrammamary infection and its relation to somatic cell count

Equations for predicting milk and curd loss due to intramammary infection in sheep and goat herds were derived. The empirical equations were derived from previously published studies conducted by this team with Assaf sheep and crossbreeds of goats in Israel. From these equations, it appears that infection of 25, 50 and 75% of the udders in a given herd was associated with loss of 4.1–12.2.5% milk in sheep and 0.8–2.3% in goats; whereas curd loss was 5.2–15.5% in sheep and 3.3–9.8.9% in goats. Based on percent of udder infection and projected SCC, the following categories are suggested for classification of sheep and goat milk: i. High-quality milk <800,000 SCC/mL, associated with infection of ∼25%; ii. Medium quality milk <1,500,000 SCC/mL, associated with infection rate between 25 and 50%; iii. Low-quality milk >1,500,000 SCC/mL, associated with infection rate above 50%; iv. Milk containing >3,500,000 SCC/mL should not be accepted for human consumption.

P556 Optimisation of afiow cytometry protocol for detection of Cryptosporidium parvum in hospital tap water and human stools

This study was designed to investigate an outbreak of high mortality that occurred in naïve Assaf sheep introduced into a Latxa sheep flock in the Basque Country, a region where piroplasmosis is endemic. To identify the causes of this outbreak, a panel of different methods, including traditional pathological, biopathological and parasitological analyses combined with recently developed molecular methods, was used. These novel molecular methods included a multiplex real-time PCR assay to screen for the presence of the most important tick-borne pathogens (piroplasms and anaplasmas), followed by a second species-specific multiplex real-time PCR assay for the identification of Anaplasma-positive samples. The identification of piroplasm-positive samples was carried out by a multiplexed microsphere-based suspension array using a Luminex® xMAP technology-based procedure. Anaplasmas and/or piroplasms were detected in 7/10 lambs and 11/13 ewes, with Babesia ovis being detected in 12 of the 23 animals, Theileria ovis in 6 and Anaplasma ovis in 4, both as single and mixed infections. Most of the animals infected with B. ovis had a marked decrease in the values of the red blood cell parameters. Ticks collected from the animals were identified as Riphicephalus bursa, recognised vector of B. ovis. Other haemolytic pathologies (clostridial disease, copper poisoning and leptospirosis) were ruled out and, considering all clinical, laboratory and epidemiological data, babesiosis by B. ovis was diagnosed. A detailed description of the clinical outcome, with ca. 60% of mortality, laboratory results and epidemiological findings are provided. The implications of the introduction of naïve animals into a piroplasmosis endemic area are discussed.

The ratio between dietary rumen degradable organic matter and crude protein may affect milk yield and composition in dairy sheep

The current ruminant protein systems aim at synchronizing the provision of rumen degradable organic matter (RDOM) and degradable crude protein (RDCP) but no specific information on their optimal ratio for dairy sheep is available. We studied the effect of the ratio of RDOM to RDCP on milk yield and composition, during a summer lactation, in 34 confined Assaf sheep managed under farm condition. Individual feed intake was assessed by using PEG (MW 4000) as external marker of fecal output, and indigestible INDF as internal marker of digestibility. Four total mixed rations contained two levels of RDCP (108 and 117 g/kg DM) and two levels of RDOM (510 and 570 g/kg DM). This resulted in one diet featuring high (5.3), one diet featuring medium (4.8) ratio, and two diets featuring low (4.5) ratio of RDOM to RDCP. Individual DM intake, digestibility, and the daily yields of milk components were not affected by RDOM, RDCP or RDOM/RDCP. High RDOM/RDCP tended ( P < 0.10) to be associated with higher milk yield, and lower ( P < 0.05) CP content. The casein/CP ratio and urea-N in milk were lowest when both dietary RDCP and RDOM were low, whereas lactose was highest ( P < 0.05) when both RDOM and RDCP concentrations were high. Our data suggest that RDOM and RDCP interact on milk composition in a way that is not fully encompassed by the RDOM/RDCP ratio and that the use of this ratio to formulate diets for pre-determined milk composition is not warranted.

Reproductive Performance and Milk Production of Assaf Sheep in an Intensive Management System

The Assaf breed of dairy sheep, a stabilized cross of the Awassi and East Friesian breeds, has replaced the Awassi as the breed of choice in its country of origin, Israel, and has spread to other Mediterranean countries. In Israel the Assaf breed is managed under an intensive production system involving weaning lambs at birth, rearing them artificially, and milking ewes after parturition. There are several breeding periods in the year when ewes are mated following hormonally synchronized estrus. Records of 18,976 lactations from 5 farms were analyzed to investigate factors that influenced Assaf milk and reproductive performance. Lactation curves were fitted to each lactation, and a range of parameters and calculated values were analyzed. Daily milk yield records also were analyzed to describe a typical Assaf lactation and compared with those of the Awassi breed. Factors affecting age at first lambing also were studied. An average Assaf ewe kept under this intensive management regimen was found to produce 334L of milk during a 173-d lactation. Mean litter size was 1.57 lambs/ewe lambing, and lambing interval was 272 d. Milk production was affected by litter size, with twin- and triplet-bearing ewes producing approximately 20L more milk per lactation than single-bearing ewes. Day length was the major environmental variable influencing milk yield. The difference between midsummer and midwinter day lengths accounted for a difference in daily milk yield of 0.44L in favor of summer. Ewe lambs that were mated for the first time at later ages produced more lambs and more milk due to greater early lactation characteristics. Milk production was found to be negatively associated with subsequent reproductive performance. Comparing these results with those from an earlier study in the Awassi breed, the Assaf was found to produce less milk during a shorter lactation than the Awassi, but its greater litter size made it a more profitable breed.

Udder disease etiology, milk somatic cell counts and NAGase activity in Israeli Assaf sheep throughout lactation

Bacterial pathogens causing udder infections in Israeli Assaf dairy sheep were identified and changes occurring throughout lactation were monitored to study the correlation between the contaminant and the severity of the infection, as measured by somatic cell count (SCC) and NAGase tests. A total of 159 Israeli Assaf dairy sheep on one farm, in their first (69), second (13) or third and more (77) lactations were included in this study. Udder halves were tested for bacterial condition, SCC and NAGase activity 2–3 weeks post lambing and every 4 weeks after until drying-off. At first sampling, in 60.7% (193/318 quarters) of the halves no bacterial growth (NBG) was detected. Different species of coagulase negative staphylococci (CNS) were the main pathogen group in infected udders. Streptococci were isolated from 14 halves, most of them in the two udder halves. The percent of udder infection in sheep in their third or further lactations was 2.8 greater ( P<0.05) than in that of sheep in their first lactation. During the lactation, 90.6% of the halves did not change their classification status, suggesting that most infections occur before lambing and/or during the following first few days. The arithmetic mean of SCC and NAGase of total half udder milk and samplings (during the lactation) were 1144±48×10 3 cells/ml and 49.4±2.5, respectively. The average SCC in the milk of halves classified as NBG was 321±35×10 3 cells/ml and was not significantly changed during the lactation period. In halves infected with CNS, average SCC was 1371±150×10 3 cells/ml at the first testing and increased to 2129±347×10 3 cells/ml at drying-off. No significant differences were found in SCC and NAGase activity between the different species of the CNS. The mean SCC over the types of bacteria isolated, lactation number and days in lactation was significantly different ( P<0.0001). In 4% of the halves, from all samples, SCC was above 5000×10 3 cells/ml although no bacteria were detected in their milk. The higher SCC in the CNS infected halves contrasted with the more moderate SCC found in dairy cows similarly infected, suggesting that the sheep udder has a lower resistance and an augmented immunological response against this group of bacteria. Thus, this should be considered accordingly in schemes for sheep’s milk quality payment.

An outbreak of abscess disease associated with shearing

This note reports an outbreak of abscess disease caused by Staphylococcus aureus subsp. anaerobius occurring in a 250 Assaf sheep flock located in Salamanca (north-central Spain). Thirty-nine of the 55 animals (71%) of the young female group (6–7 months old) selected for breeding were affected by the disease. No abscesses were detected in the adult ewes. Clinical cases were first detected 3 weeks after shearing. In consideration of known data on experimental infections of sheep with S. aureus subsp. anaerobius, it is highly probable that the animals in the present outbreak became infected about shearing time. Therefore, shearing was the risk factor most probably associated with the outbreak.

Inheritance of birthweight and growth traits in crosses between the Booroola Merino and Assaf sheep breeds

Data on birthweight, pre and post weaning growth rates and 150 day weight of 1058 Assaf (As), Booroola Merino (B) × As (F1), F1 × As ( 3 4 As ), As × F1 ( 3 4 As′ ), As × 3 4 As ( 7 8 As ) and B × F1 ( 3 4 B ) lambs were analyzed. Genotype, sex of lamb, genotype by sex interaction, crop, type of birth and sire within genotype had significantly ( P< 0.05) affected the different traits. Assaf lambs had the highest and 3 4 B lambs had the lowest birthweights. A negative relationship was found between the birthweight and the proportion of the Booroola blood in the lamb and its mother. As, F1, 3 4 As, 3 4 As′ and 7/8As ram lambs did not differ significantly ( P> 0.05) in their post weaning growth rate and in their 150 day weight. Similar situation was found among ewe lambs except for F1 ewe lambs which were significantly ( P< 0.05) smaller than Assaf ewe lambs at 150 days indicating sex linked effect on growth in the Booroola-Assaf crosses. The Assaf transmitted effects were positive and significant ( P< 0.05) for birthweight, post weaning growth and 150 day weight, and the Assaf maternal effect was positive and significant ( P< 0.001) for birthweight. Significant ( P< 0.001) heterosis was found for post weaning growth rate. Sex linked and recombination effects were significant ( P< 0.01) for pre weaning growth.

Contemporary performance comparisons of Chios and Assaf sheep and of their crosses under intensive indoor management. Preliminary results

Summary Ten Chios ewe hoggets and three rams were imported from Cyprus and their performance was compared with that of 49 Assaf (East Friesian X Awassi) contemporaries. Lambing rates (lambs/ewe/year) for the Chios and Assaf ewes in the first and second to fifth lambings were 1.89 and 1.42 (P < 0.01), and 2.10 and 1.69 (P < 0.03), respectively. Yearly milk yields were 206 ± 30 and 225 ± 16 ; not significant (NS) and 269 ± 31 and 345 ± 22 kg (P < 0.05), respectively. There were no significant differences between the two breeds in lambing interval and in lamb mortality. There were no significant differences between 47 Assaf and 35 Chios X Assaf (ChAs) ewes born in Israel for age at first lambing (435 and 428 days), percent of ewes lambing (96), lambing interval (280 and 293 days), mature body weight (80.5 and 77.4), lambs born/lambing (1.40 and 1.59 at first and 1.71 and 1.75 at 2nd to 5th lambings), lamb mortality (9.9 and 12.2 p. 100), or milk production per lactation (211 and 192 kg) in first lactation. Mean milk yields in 2nd to 5th lactation were 270 ± 18 and 219 ± 16 kg, respectively (P < 0.05). Chios lambs grew significantly slower compared with the Assaf and crossbred lambs.