Fat-tailed Breeds Research Articles

“By endurance we conquer”: fat tailed sheep in the twenty-first century

In the temperate world, sheep are usually classified under two categories: wool and hair, where the latter are, in most cases, considered a relic of medieval times and not suitable for contemporary commercial sheep production. Additionally, in temperate countries, the sheep world is usually in black and white, as no other colors or mixing are commonly found. Interestingly, hair breeds are very adaptable to harsh environments like the churra breeds of the Iberian Peninsula or the Scandinavian hair breeds that thrive respectively in cold mountain ranges and sub-arctic islands. In the Tropics, however, the ovine world changes considerably: sheep have often (short) hair that tends to shed with changing seasons, and wool sheep are indeed a rare oddity. Additionally, tropical sheep are present in a vast array of coat-color patterns that eclipse the monochromatic nature of their relatives of temperate (mostly European) relatives. Besides these features, tropical sheep have a very distinctive and particular trait: the fat tail and/or fat rump, and are generally described as fat-tailed sheep (see Fig. 1). This morphological feature is characterized by an accumulation of fat mainly at the level of the hind quarters in varied shapes and volumes, and it is assumed to have similar physiological roles as those of the zebu or camel humps. Fat-tailed sheep distribution encompasses vast areas of the globe. They are the main ovine genetic resource in the Middle East and North Africa, Iran, Pakistan, Central Asian Republics, China and Mongolia, East and Southern Africa, and have important populations in agricultural export giants like Brazil or Australia. Interestingly, as to the best of our knowledge, in temperate countries, namely the European Union territory, there is only one autochthonous fat-tailed sheep breed: the Chios breed from the homonymous Greek Island near the Turkish coast. Regarding international diffusion, only two fat-tailed breeds may be classified as having acquired such preponderance: the Awassi breed original from several Middle East countries, improved in Israel and from there widespread to the entire world as a selected dairy breed and the Karakul (Astrakhan) breed form the former Soviet Union Republics of Central Asia that gained importance in the pelt production industry, curiously in fat-tailed sheep home range: Southern Africa and that nevertheless has lost the importance of the 1960s and 1970s. The wide distribution of fat-tailed sheep breeds may be explained by one particular trait: adaptability or endurance. In fact, these animals are able to thrive under extremely harsh conditions; they are able to tolerate hot weather, cope with dry environments with low pasture availability, able to walk long distances in search for pastures and drinking water, tolerate diseases and parasites, and even have gregarious and defense instincts that enable them to defend the flock from predators like jackals or foxes, similarly, to A. M. Almeida IICT–Instituto de Investigacao Cientifica Tropical & CIISA– Centro Interdisciplinar de Investigacao em Sanidade Animal, Lisbon, Portugal

The effects of diet, slaughter weight and docking on growth, carcass composition and meat quality of fat-tailed Barbarine lambs. A review

This review summarises the main factors that influence meat production and quality in fat-tailed Barbarine (FTB) lambs. As a general feature, FTB lamb's growth is moderate, and the average daily gain ranges between 100 and 350g. The carcass being relatively fatty, carcass fat content varies from 10% to 32%; white fat and rose meat are often dominant in these carcasses. The meat fatty acid profile of this fat-tailed breed is similar to that of thin-tailed ones, with a prevalence of palmitic, stearic and oleic acids. The order of dissected adipose tissues accumulation, estimated by allometry coefficients, is in agreement with observations in thin-tailed sheep. However, tail fat allometry coefficient is closer to kidney fat values rather than to the subcutaneous one. Concerning effects of feed level, growth of FTB lambs fed silage is higher than those fed oat hay. With moderate concentrate supply, FTB lambs' growth is more pronounced on pasture diet than on the feedlot (FL) diet. Furthermore, at similar slaughter weights, carcasses of lambs fed pasture diet have less tail and carcass fat than those from lambs fed FL diet (5% and 18% vs. 9% and 24% for grazing and FL lambs, respectively). No difference in fat colour, fat firmness or cooked meat flavour is observed between carcasses obtained at different slaughtering weight (i.e. from 25 to 35kg). The tail docking of FTB improved lambs' growth particularly before weaning. Its effect on carcass composition and fat proportion depends on stage of slaughtering and type of fattening diet. For suckled lambs (4months), the docking resulted in the lower carcass fat weight (and proportion), while for fattened lambs, carcass composition was similar for all types of lambs. Overall, FTB lambs always grow slower than Noire de Thibar lambs. This is particularly pronounced during the fattening phase. Then, for FTB breed, the possibilities to obtain heavy carcasses are at risks of fat accumulation, 22.8% vs. 14.4% for FTB and Noire de Thibar thin-tailed lambs, respectively. However, the main advantage of FTB breed is that adults are well adapted to food scarcity and may produce lambs even under harsh conditions.

Grazing behavior of sheep at different stocking rates in the Inner Mongolian steppe, China

In free-ranging or grazing animals, physical activity can account for a substantial proportion of their total energy requirement with considerable consequences for animals at low production level. This study evaluated the effect of grazing intensity (GI) on behavior and walking distance of sheep grazing the Inner Mongolian steppe, China. In July 2008, 70 female fat-tailed breed sheep were randomly assigned to one of six GI plots, which were used according to the following herbage allowance (HA) classes: >12, 6–12, 4.5–6, 3–4.5, 1.5–3, and <1.5 kg dry matter kg −1 live weight corresponding to very light (GI 1), light (GI 2), light-moderate (GI 3), moderate (GI 4), heavy (GI 5), and very heavy (GI 6) grazing. The sheep were continuously on the plots throughout the grazing season until September 2008. Behavior of two sheep per plot was monitored by visual observation during daylight on two days in the beginning of each month. Walking distance was measured by global positioning system recorders between 12:00 h and 24:00 h. Organic matter (OM) intake was estimated in six sheep per plot using titanium dioxide as external fecal marker as well as the diet OM digestibility derived from fecal crude protein concentration. Two main grazing periods were observed at all GIs with afternoon grazing being longer than morning grazing. GI had no effect on the animals’ ruminating time and walking distance. However, with increasing GI sheep spent more time grazing and less time resting during daylight. Similarly, the animals tended to decrease their resting time in order to maintain their grazing time when daylight became shorter with advancing vegetation period. Thereby, they succeeded in maintaining their OM intake as GI increased from GI 1 to GI 5 despite lower HAs at high GIs. Nevertheless, OM intake was lower in GI 6 than in GI 2 and GI 3 sheep. Therefore, both, reduced feed intake and higher energy requirements for activity, will outweigh the expected profit from highly intensive grazing.

Genetic variations between indigenous fat-tailed sheep populations

.Blood samples were collected from a total 816 sheep of both sexes in three Iranian fat-tailed breeds (Sangsari, Makoei, indigenous sheep on firoozkouh mountain) serum, plasma and erythrocyte were separated and were frozen at -20°C. Variation in their blood proteins, albumin, haemoglobin and transferrin were examined to characterize the breeds and to obtain genetic relationship among them. Only transferrin was polymorphic in all breeds investigated; while albumin was monomorphic for S allele and haemoglobin was fixed for the B allele in three breeds.

Performance traits of purebred Ossimi and Rahmani lambs and their crosses with Finnsheep born under two accelerated mating systems

Abstract. The aim of the study was to carry out crossing of the local breeds with a known prolific breed with the hope to be a beginning to develop improved synthetic lines under the sub-tropical conditions. In the present study, the data represented 4 genotypes: 2 pure Egyptian local fat-tailed breeds [Ossimi (O) and Rahmani (R)], one back-cross [1/4 Finnish Landrace (F) 3/4 O] and one 3-breed-cross [1/4 F 1/4 O 1/2 R]. The lambs resulted from two accelerated systems: 3 lambings/2 years and 2 lambings/1 year. The results showed that in 3 lambings/2 years and 2 lambings/1 year systems, the crossbred lambs were significantly (P&lt;0.01 or 0.05) higher in most of the growth traits, carcass characteristics and weight of ewe lambs at first mating, and were significantly (P&lt;0.01) lower in percentages of the tail and bone and age of ewe lambs at first mating than in their maternal (local) breeds. Spring born lambs were significantly (P&lt;0.01 or 0.05) higher than those born in the other seasons of the year in body weights at 16 and 24 weeks of age and daily gain weight during 0–&lt;8 weeks in 3 lambings/2 years system, and in daily gain weight during the period 8–&lt;16 weeks of age in 2 lambings/1 year system. When using some indices based on combining a number of economic traits of the study (including slaughter weight, feed efficiency, dressing percentage, percentage of lean in the carcass, conception rate, lambing rate and average litter size) to compare the crossbreds with the local ones, the obtained values were not in favour of the crossbreds, which may throw some shadows on feasibility of applying crossing of the Egyptian local sheep with the Finnsheep. Comparison between the two mating systems showed that the 3 matings/2 years surpassed the 2 matings/1 year system in all the indices developed. When calculating the productive efficiency per one year by combining the traits: survivals ratio – that equals: 1 − (mortality rate at 8 weeks) – and frequency of lambing per one year, the values were 15.0 and 13.2 % in the two systems, respectively, confirming the previous results.

Beta-Lactoglobulin Gene Types in Turkish Fat-Tailed Sheep Breeds

Summary The genetic polymorphism of the β-lactoglobulin gene was investigated in 182 sheep of Turkish fat-tailed sheep breeds by using PCR-RFLP methods. In the study, two alleles (A and B) and three genotypes (AA, BB and AB) at β-lactoglobulin locus were observed. The most common genotype at the β-lactoglobulin locus was AB. The greatest frequency of allele A was detected in Tuj breed as 0.7188. Results of the present study show that genetic polymorphism exists in the Turkish fat-tailed sheep breed population used in this study.

Lambing season and fertility of fat-tailed ewes under an extensive production system are associated with liveweight and body condition around mating

The objective of this study was to investigate to what extent fertility and lambing season of fat-tailed ewes raised under an extensive production system are related to liveweight, body condition and changes around mating. Ewe liveweight and body condition score (BSC) were recorded in June, July and August over a period of 3 years (1999–2001) in 11 flocks (eight flocks of Kurdi breed and three flocks of Kurdi × Sanjabi crossbred). Both Kurdi and Sanjabi are native fat-tailed breeds in western Iran. In total, 3278 lambing records relating to 1592 ewes and data on mating date, liveweight and BCS of 1930 ewes (3975 records) were used for statistical analyses. The statistical model for bodyweight and body condition data included fixed effects of breed group, flock nested within breed group, year, the future lambing status following summer breeding (barren, autumn lambing and winter lambing), ewe age and all two-way interactions. Breed group had a significant effect on ewe liveweight (P &lt; 0.01). However, there was no significant difference between BCS of the two breed groups around mating. Ewe liveweights measured in June, July and August had significant effects on fertility and lambing season (P &lt; 0.01). Ewes that produced lambs were generally heavier at mating than barren ewes (P &lt; 0.01). Autumn-lambing ewes were heavier than winter-lambing ewes in June and July (P &lt; 0.01). Effects of changes in liveweight on fertility and lambing season were significant (P &lt; 0.01). The effects of BCS in June, July and August (P &lt; 0.01) and changes in BCS during the mating period (P &lt; 0.05) on fertility and lambing season were also significant. The mean BCS (in June and July) of autumn-lambing ewes was greater than that of the winter-lambing and barren ewes (P &lt; 0.05). The proportion of autumn-lambing ewes significantly increased as BCS in July increased, whereas the proportion of barren ewes decreased (P &lt; 0.01). Fertility was associated with age so that as the age of the ewes increased from 2 to 7 years, the proportion of barren ewes significantly decreased from 29 to 5% (P &lt; 0.01). There was a relatively high proportion of very thin ewes of 2 and 3 years of age. These findings imply that low body condition is a particular problem in younger ewes suggesting the importance of giving special nutritional treatment to younger ewes to reduce the proportion of barren ewes.

Monitoring crossbreeding trends in native Tunisian sheep breeds

Important urban market changes have been noticed in Tunisia for animals that produce thin tail carcasses in contrast to carcasses of animals with a fat tail. In response to this trend, farmers are crossing the local Barbarin (a fat-tailed breed) with thin tailed breeds (Algerian Ouled Djellel and Black Thibar). This happens while the fat tail is known as a criterion of adaptation to harsh conditions and fat-tailed animals are preferred for religious practices. The objectives of this study were to identify hidden reasons for these changes and assess the degree of crossbreeding between the Barbarin sheep and thin tailed breeds. A total of 912 surveys were conducted in three major sheep regions covering the capital (Tunis) and five departments, and including 601 sheep owners, 158 butchers and 153 consumers. The main results showed that even though raising sheep is still as an activity by itself, fattening activities (breeding–fattening or only fattening) are becoming more and more dominant and they represented 75%, 53% and 65% of the sheep activities in the capital Tunis, South East and North West regions, respectively. While breeders and consumers still prefer, in their majority (55–75%), the Barbarin fat tail lambs, butchers tend to favor thin tailed sheep because of the difficulty of selling the fat of the tail that represents up to 15% of the carcass weight. To meet the butchers’ demand, farmers are shifting to thin tail breeds and crosses and in the studied areas, market changes towards thin tailed breeds were dictated by butchers’ and not consumers’ preference. Sensory tests revealed little difference among the three studied genotypes but showed a superiority of the fat tail lambs in tenderness, flavour and smell.

Importance of awassi lambs’ in food supply, element transport and growth performance

Mutton has traditionally very important role in the food supply of the Mediterranean and Middle-East countries. Awassi is a widespread fat-tailed sheep breed of these regions, with relatively high milk productivity (Epstein, 1987). Production of this breed is mainly based on semi-intensive systems with low prolificacy and high milk production (Emsen et al, 2004). Whereas, intensive milk producing systems has become widespread in many countries to increase the milk productivity. As it is well-known from literature, Awassi sheep is able to accommodate to the conditions of intensive keeping system (Pollott and Gootwine, 2001). In addition, artificial lamb rearing is a common keeping method in intensive milk-production systems (Napolitano et al.r 1995; Martin, 1999), which forces lamb separation from dams as soon as it possible. This technology based on early, weaning and artificial rearing of lambs on milk replacer and it has an important Impact on increasing flock productivity. One of the main factors which have effect on the early.'development of lambs is the time of weaning. The first 10-12 hours post-partum is a critical, sensitive period during Which suckling plays a key role for the establishment of the mother-lamb bond (Alexander et al., 1986; Napolitano et al., 1995; Nowak et al., 1997; Fisher and Matthews, 2001). It is known that lambs permanently nursed by their dam do not accept being bottle-fed and do not socialise to humans at a young age, despite regular short sessions of human petting (Boivin et al, 2001). As expected from literature, lambs separated early from their mother, readily accepted additional human contact including drinking from a bottle or a bucket of milk (Markowitz et al, 1998; Boivin et al, 2001). Awassi sheep has recently been introduced in Hungary as well (by Bakonszeg Awassi Ltd.), based on an Israeli flock imported in 1989. This breed indicates favourable results in Hungary, primarily in intensive milk production. Whereas, technological difficulties arose, related to the handling of a few lambs. These lambs were not removed from dam immediately after parturition (birth at late-night or early dawn) and were not accept bottle-feeding and artificial teats. Therefore, the aim of this experiment was to investigate the effect of weaning time on early development and growth performance of lambs, considering to the different separation moments during the sensitive period (10-12 h postpartum).

Estimation of sheep carcass traits by ultrasound technology

Real-time ultrasound technology offers the possibility of estimating carcass characteristics in live animals and represents a potential method for selection of breeding stocks. A total of 745 live lambs born during 2001–2003 into two flocks was used to estimate rib muscle and fat depth by ultrasound. Lambs came from 559 ewes and 97 rams of a fat-tailed breed, known as the ‘Barbarine’ in North Africa. Ultrasound measurements of external fat thickness (UFD) and muscle (UMD), taken at the 12–13th rib and palpation of body conditions (loin and tail scores) were made for 150 days until lambs 520 days old of lamb ages. Main results showed that UMD and UFD had the same trend as live weights from 150 to 240 days old. They decreased from 150 to 200 days old, and then increased. The same trend was seen for loin and tail scores. Average differences in live weights between male and female lambs were 1, 3 and 6 kg at 30, 90 and 120 days old, respectively. The highest muscle depth for males was reached at day 180 and the lowest fat depth was recorded between 180 and 200 days. Average loin scores became greater for males than females from 240 days of age. Male lambs had greater tail scores at all ages, from 150 to 520 days old. Differences became greater for ages more than 180 days, showing that males have a tendency to store more fat in their tails than females. Phenotypic correlation was 0.70 between muscle depth and loin scores, indicating that, at 180 days old, the Barbarine breed has more muscle and less fat. The optimum slaughter age was defined between 180 and 200 days old, producing carcasses with more muscle and less fat. Regression equations estimating carcass traits (UMD, UFD) at 180 and 240 days old were computed.

Effect of breed and age on sexual behaviour of rams

The objective of this study was to highlight the problems that arise during the reproduction between thin-tailed rams and fat-tailed ewes. At the same time, particular emphasis laid on the influence of sheep breed, sheep age, time after ram introduction and day of the ewe estrus cycle on ram and ewe sexual behaviour. Rams were subjected to sexual performance tests by being individually exposed to 12 ewes for 3 h daily, 19 consecutive days. The 16 rams of the experiment were separated according to their age (9 and 21 months old) and breed (Chios and Karagouniki), and the 96 ewes of Chios fat-tailed breed, were divided by age (9 and 21 months old). The main characteristics of courtship behaviour, like sniffing, nudging, flehmen response and following were recorded and studied in detail. Mature Chios rams, which were the only one with previous experience of Chios ewes, exhibited higher rates of sexual interest per ewe than the other rams ( P < 0.05). On the other hand, rams sniffed and nudged more young than mature ewes ( P < 0.05), probably due to the fact that young ewes did not express intense symptoms of estrus. Young rams exhibited substandard sexual interest towards mature ewes, when they first came in contact with them ( P < 0.05). In general, Karagouniki thin-tailed rams exhibited reduced rates of mating behaviour when they courted with Chios fat-tailed ewes in comparison with Chios rams ( P < 0.05). Moreover, as the time after ram introduction passed, the frequency and duration of sexual behaviour components decreased ( P < 0.001). Finally, the effect of the day of the experiment was only significant in the case of sniffing, which increased during the first 2 days and then declined and stabilized ( P < 0.01). As it was demonstrated, ram age and ram breed played a fundamental role in the exhibition of sexual interest elements.

Effects of two beta-adrenergic agonists on adipose tissue, plasma hormones and metabolites of Moghani ewes

The effects of different levels of dietary terbutaline (T) and metaproterenol (MP) on adipocyte size, plasma hormones and metabolites in Moghani ewes (a native fat-tailed breed) were examined. MP and T were administered at 0, 5 (low dose), 10 (middle dose) and 20 (high dose) mg/kgDM in a concentrate diet. Plasma concentrations of insulin, T 4, triglyceride, cholesterol, high and low density of lipoprotein (HDL and LDL) were measured on days 60 and 90 of fattening period. Adipose tissue samples of fat-tail were taken after slaughtering the animals. Both beta agonists decreased the diameter of fat-tail adipocyte ( P < 0.01). Plasma concentration of insulin was decreased in ewes receiving low dose of MP on days 60 and 90, likewise middle dose of T, low and high doses of MP on day 90 decreased plasma insulin ( P < 0.05). T 4 plasma concentration was increased on day 60 by middle dose of both beta agonists ( P < 0.05), but this effect was not observed on day 90. Treatment of ewes with low and high doses of T and high dose of MP decreased the plasma concentration of triglycerides on day 90 ( P < 0.05). Three levels of MP decreased cholesterol plasma concentration on day 60 ( P < 0.05). This effect was not statistically different on day 90. Low dose of MP decreased plasma HDL on days 60 and 90, likewise middle dose of T and middle and high doses of MP decreased plasma HDL on day 90 ( P < 0.05). Three levels of T and MP on day 60, and low dose of MP on day 90 decreased plasma LDL ( P < 0.05). It is concluded that the measured repartitioning effects of T and MP were within the range of effects observed for thin-tailed sheep and other animals, but their effects on size of fat-tail adipocyte are particularly seen in Moghani ewes.

Growth performance and carcass quality of fattening lambs from fat-tailed and tailed sheep breeds

The growth performance and carcass traits of two fat-tailed breeds ( Chaal and Zandi) and their crosses with rams of a tailed breed ( Zel) were compared. After weaning, the growth and feed consumption of male and female lambs fattened for 114 days were recorded. A total of 45 male and female lambs were slaughtered and the left side of the carcasses were cut into six pieces, and the lean meat, bone, subcutaneous and intermuscular fat were determined. Average daily gain and feed conversion ratio in crossbred lambs improved, but the differences with pure lambs were not significant. The average weight of shoulder, brisket and loin were higher in crossbred than pure breed lambs ( P < 0.01). The percentage of protein in the carcass of Zel × Zandi lambs was significantly higher than Zandi lambs. The smaller size and lower weight of fat-tail in crossbred lambs were compensated by higher percentage of subcutaneous, intermuscular and internal fat. The fat-tailed breeds provided good quality lean meat in terms of lower percentage of intermuscular fat.

Comparison of growth and feed-lot traits in Kordi crossbred and purebred lambs (crossbreeding between some Iranian fat-tailed breeds)

Meat production is the most important goal of sheep breeders in Iran. Crossbreeding between rams from relatively heavier breeds with ewes from light breeds (terminal crossing) is common method for increasing meat production in many countries (Bunch et al., 2004; Guney, 1990; Macit et al., 2001). The objective of this study was to compare the growth and feed-lot performance of crossbred lambs, resulted from Shall, Moghani and Afshari (three heavy breeds) rams and Kordi (a light breed) ewes. The performance of pure Kordi lambs was also adopted as a comparison benchmark.

Growth and carcass composition of tropical fat-tailed Menz and Horro sheep breeds

AbstractThe pattern of growth and carcass composition of indigenous Ethiopian fat-tailed Menz and Horro lambs were assessed through serial slaughter and carcass dissection of 147 lambs at five different growth phases. The GLM procedure of Statistical Analysis Systems Institute and allometric growth equations were used to assess the effects of various factors and differential growth of carcass components, respectively. Results showed that the growth and carcass composition of Menz and Horro lambs was significantly (P &lt; 0.05 to P &lt; 0.001) affected by the genotype, growth phase and season of birth of lambs. The effects of growth phase clearly showed that slower growth of the body and of carcass components was observed during the third phase (i.e. after weaning). Although there was an effect on fat to lean ratios (P &lt; 0.05), growth phase had no significant effect on dressing out proportion, and lean to bone ratios. A significant influence of genotype (P &lt; 0.001) and sex (P &lt; 0.05) on lean to bone ratios indicated that the Horro sheep and ram lambs had a much more developed and heavier skeleton than the Menz sheep and ewe lambs. Higher pre-slaughter, hot carcass, lean and bone and fat weights of May/June born lambs revealed significant advantages of wet season lambing for fast growth and improved carcass composition. The log/log regression of weights of dissectible carcass components on hot carcass and empty body weight showed that the differential growth of bone was declining and that of lean was isometric relative to the growth of empty body weight. For carcass fat, the allometric growth coefficients (b) of 1.5 and 1.8 for Menz and Horro sheep, respectively indicated that fat is a late maturing body component. Moreover the growth of carcass fat relative to empty body weight in the Menz and Horro sheep is slower than that reported for tropical sheep breeds.

Using Linear Body Measurements of Live Sheep to Predict Carcass Characteristics for Two Iranian Fat-tailed Sheep Breeds

Live animal selection programs that favor animals with a minimum amount of carcass fat are used for improving breeding flocks of sheep. To predict carcass characteristics of live sheep using body measurements in breeding flocks, 200 male and female lambs of two fat-tailed Iranian sheep breeds (Moghani and Makui) were used. Depth of soft tissue over the 12th rib of the live animals was measured with ultrasound (ULGR) and with hypodermic needle (NGR). The height at withers (HW), body length (BL), circumference of heart girth (CH) and width of hooks (WH), were measured. All animals were slaughtered; carcasses were cut into joints and dissected. Breed had a significant effect on all of the live measurements. The Moghani breed showed a higher value for HW, CH, ULGR and NGR, compared to that of Makui. Except for soft tissue depths; ULGR, NGR and GR, the male lambs showed higher values in live and carcass measurements than females. Percentages of carcass, total fat and intermuscular fat in females were higher than that of male lambs. In spite of the higher amount of subcutaneous and intermuscular fat in female (which is usually used for their physiological need, such as pregnancy and lactation), the male lambs had a heavier fat-tail than females. There was a wide range of variation of percentage of total carcass fat and total chemical fat content of carcass in the two breeds. Eventually this wide variation could be use by animal breeders for selection of animals with a lesser amount of carcass fat. Live weight of lambs showed a relatively low correlation with percentage of carcass lean, total fat and subcutaneous and intermuscular fat. Total lean meat was predicted with relatively high coefficients of determination in the two breeds (R 2 =0.61 and 0.89, respectively). Live weight and carcass traits were predicted using simple measurements, but with R 2 ranging from 0.53 to 0.93. (Asian-Aust. J. Anim. Sci. 2004. Vol 17, No. 5 : 693-699)

Effects of calcium salts of fatty acids on follicular characteristics and several blood parameters in two fat-tailed sheep breeds

There is substantial evidence that the increased consumption of fat by dairy cattle can result in an increase in the number ovarian follicles, and the number and size of corpora lutea; it also stimulates post-partum ovarian activity and improve pregnancy rate. Increased dietary lipid also increases plasma cholesterol and progesterone, and the supply of lipoproteins which play significant roles in regulating ovarian steroidogenesis (Willimas, 1996). In contrast to cattle, there are few observations on the effects of dietary lipid on reproductive function in sheep. Intravascular infusion of lipid into ewes stimulated progesterone and prostaglandin synthesis (Burke et al., 1996), and dietary supplementation of calcium soaps of fatty acids enhanced luteal function (Kuran et al., 1999). Calcium soaps of fatty acids have been manufactured in Iran in recent years and sold under the trade name of Megalac. The aim of the present experiment was to study the effects of this protected fat on follicular number and luteal activity in two fat-tailed sheep breeds.

Genetic and economic analysis of introgression the B allele of the FecB (Booroola) gene into the Awassi and Assaf dairy breeds

Selection for yield and the adoption of an intensive management system underpins the high milk production of the Improved Awassi and the Assaf dairy flocks in Israel. However, lamb production, which contributes some 40% of the income, remains relatively low at 1.2 and 1.6 lambs born/ewe lambing (LB/EL) for the Awassi and the Assaf, respectively. To increase the profitability, through improved lamb production, a breeding scheme was initiated in 1986 to introduce the B allele of the FecB (Booroola) gene to the Awassi and Assaf breeds. This led to the formation of the Afec–Awassi and Afec–Assaf strains with prolificacy of about 2.0 LB/EL. A marker assisted selection approach and the use of induced ovulation rate as selection criteria were incorporated into the breeding programs. The Awassi is the main type of sheep in the Middle East where about 80 million sheep of this breed and other related fat tail breeds are present. Distribution of the BB Afec semen or rams in those flocks, through regional breeding programs, can improve their productivity and their economics, facilitating the transition into a more intensive production system. The economic justification for launching such a breeding program depends mainly on the local lamb price.

Effects of Grass Lipid and Its Fatty Acids on Ruminal Fermentation and Microbial Growth In Vitro

Considerable concern has been expressed by the Australian wool industry regarding the contamination of the clip with coloured or kempy fibres from imported breeds of sheep. As part of the evaluation of imported sheep meat breeds in western Queensland, a study is examining fibre growth and transfer of fibres and the potential to cause physical contamination of Merino fleeces. The breeds of concern in this study are the Damara, a fat-tailed breed with a hairy, coloured fleece and the Dorper which has both pigmented fibres and a kempy fleece which is shed cyclically. Three groups of Merino 27 ewes were mated to Merino, Damara and Dorper rams respectively and fibre transfer to the Merino ewes during mating, from lambing to weaning and during grazing, assessed. Both a direct field method and a laboratory method (Hatcher 1995) are being used. Those measured by direct count were measured immediately after joining and 2, 4 and 8 weeks subsequently. and the other ewes were shorn and sampled and measured in the laboratory using the dark fibre detector. This paper presents preliminary findings of those ewes monitored by the direct field method. Animal production for a consuming world : proceedings of 9th Congress of the Asian-Australasian Association of Animal Production Societies [AAAP] and 23rd Biennial Conference of the Australian Society of Animal Production [ASAP] and 17th Annual Symposium of the University of Sydney, Dairy Research Foundation, [DRF]. 2-7 July 2000, Sydney, Australia.

Effects of vitamins A and E supplementation on vitamins A and E status of blood plasma, liver and tail fat of fat-tailed sheep

Ram lambs of two Iranian fat-tailed genotypes, Shal (4–6 months) and Sanjabi (6–9 months) were used in experiments for 95 days. They were assigned (25 lambs per breed) into five groups for each breed to receive basal diet plus different levels of vitamins A and E supplementation. The vitamin A groups received 50 or 100 IU vitamin A per kg BW and vitamin E groups received 15 or 30 IU vitamin E per kg diet; the fifth group served as control. Blood plasma, liver and tail fat samples were taken at the beginning and at the end of experiments. Retinol and α-tocopherol concentrations of the samples were determined by high performance liquid chromatography. The highest level of vitamin A application increased the retinol of blood plasma ( P < 0.01) and liver ( P < 0.05) of Shal sheep. The application showed negative correlations to retinol content of tail fat in Shal ( P < 0.01) and Sanjabi breeds ( P < 0.05). The vitamin E application increased the α-tocopherol content of blood plasma in Shal ( P < 0.01) and Sanjabi ( P < 0.001) breeds as well as of liver in the Sanjabi breed ( P < 0.01). The increase was also significant for the tail fat of Shal ( P < 0.01) and Sanjabi breeds ( P < 0.05). As the result of the antagonistic effect of vitamin A on vitamin E status, α-tocopherol concentrations decreased in blood plasma ( P < 0.001), liver ( P < 0.01) and tail fat ( P < 0.001) of both breeds as an effect of vitamin A supply. On the other hand vitamin E supplementation moderately decreased the retinol content of blood plasma ( P < 0.05) in the Shal breed, at the highest level of application but the retinol content of liver tissue increased in the Shal breed ( P < 0.01). Vitamin E application increased the retinol content of tail fat of the breeds, as compared to initial values ( P < 0.05). It was concluded that Shal showed a higher response to vitamin A supplementation and Sanjabi for vitamin E. Therefore different fat-tailed breeds may demand different vitamins A and E supplementation. Concentration of α-tocopherol in blood plasma was a good indicator of vitamin E status in fat-tailed sheep. The sparing effect of vitamin E on retinol status was found in the liver of Shal breed only, but both genotypes showed that effect in tail fat. Tail fat seems to be an active tissue for storage of α-tocopherol but not for retinol at the dose which was used in this study.