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Variation in fleece characteristics of Awassi sheep at different ages
Small Ruminant Research 41 (2001) 95±100
Variation in ¯eece characteristics of Awassi sheep at different ages M.J. Tabbaaa,*, W.A. Al-Azzawib, D. Campbellc a
Department of Animal Production, University of Jordan, Amman, Jordan b IPA Agriculture Research Center, Baghdad, Iraq c DFID Livestock Project, P.O. Box 519, Jubaiha, Amman, Jordan Accepted 7 April 2001
Abstract Fleece characteristics have economic signi®cance in sheep. When assessing ®ber characteristics, the importance of sex, age of sheep and the body location of the sample taken are important considerations. Triplicate ¯eece samples were obtained from the shoulder, right mid-side and hip of 12 male and 17 female lambs (6±10 months), 62 yearling ewes (14±20 months) and 235 mature ewes (28±84 months) by hand shearing. The greasy ¯eece weight, staple length, ®ber length and ®ber diameter measures were 2:1 0:03 kg, 14 0:18 cm, 24 0:26 cm and 36 0:33 mm, respectively. Correspondingly, the medullated ®bers, inner coat, outer coat and kemp ®bers were 11:6 0:33, 59:7 0:29, 34:0 0:23 and 6:3 0:16%, respectively. Age had a signi®cant in¯uence on body weight and greasy ¯eece weight, but male and females were similar. Body location of the sample had a signi®cant effect on the ®ber diameter, and percentages of medullated ®bers, kemp ®bers, and inner coat ®bers. The ®nest ®bers and a lower percentage of medullated ®bers were found on the shoulder and mid-side, whereas, the percentage of inner coat ®bers was highest on the hip. Although there was no signi®cant interaction between body location and age±sex groups for ®ber characteristics, it was important for staple and ®ber length (P < 0:05). The wide variation in ®ber diameter and percentage of medullated ®bers suggest potential for improvement of economical traits. # 2001 Elsevier Science B.V. All rights reserved. Keywords: Wool; Fleece sampling; Fleece characteristics; Awassi sheep
1. Introduction The Awassi is a fat-tailed breed of sheep used for meat, milk and carpet-wool production. It is the most common breed in Jordan and in the Middle Eastern countries. The Awassi sheep produces good quality carpet (medium) wool. The price paid for the ¯eeces
*
Corresponding author. Tel.: 962-6-5355000/ext. 2578; fax: 962-6-5355577. E-mail address: [email protected] (M.J. Tabbaa).
is based on ¯eece characteristics, therefore, it is important to assess these traits and determine the potential for their improvement. Higher estimates of heritability have been reported for ¯eece characteristics in many breeds, therefore selection for desired traits might be useful. Furthermore, ¯eece characteristics in¯uence insulation values of the coat (Doney and Smith, 1961a) protecting the animal from the extremes heat and cold in Jordan. It has been reported that the body location of the wool samples taken in¯uences ¯eece characteristics (Doney and Smith, 1961b; Saddick, 1993; Seoudy et al., 1973; Tabbaa
0921-4488/01/$ ± see front matter # 2001 Elsevier Science B.V. All rights reserved. PII: S 0 9 2 1 - 4 4 8 8 ( 0 1 ) 0 0 2 0 3 - 6
96
M.J. Tabbaa et al. / Small Ruminant Research 41 (2001) 95±100
et al., 1998). Shoulder areas have longer, ®ner ®bers with a lower percentage of medullated ®bers than those from the mid-side and hip. Understanding the pattern of variation on the body would be useful in determining the most suitable sampling location for measuring ¯eece characteristics. There have been con¯icting reports in the literature regarding the effect of age on ¯eece characteristics. Sidwell et al. (1971) found greasy ¯eece weight increased with advancing age. In contrast, Al-Azzawi (1977) reported that ¯eece yield decreased with age. Again, Tabbaa et al. (1998) found negligible differences among ¯eece characteristics of mature Awassi ewes in Jordan. However, ¯eece characteristics of Awassi lambs have not been thoroughly investigated and compared with mature animals. Therefore, the objective was to study the ¯eece samples from various parts of the body of Awassi sheep of different ages. 2. Materials and methods The sheep ¯ock at the Jordan Ministry of Agriculture's Khanasri Animal Improvement Station in NE Jordan was assembled in the early 1970s from ewes collected from several farms, in various parts of Jordan. The rams were obtained from farmers in Jordan and Government Stations in Syria, Iraq and Turkey. The sheep were housed under a semi-intensive system with access to grazing from January to April, resulting in an intake of 18 MJ ME per day (Harb, personal communication). During the remainder of the year, 800 g of concentrate feed was provided to dry ewes. The feed supplement increased to 1.2 kg
concentrates and 0.3 kg hay during ¯ushing, lactation and the last 6 weeks of gestation. The concentrate consisted of barley grain (73%), wheat bran (15%), soybean meal (10%), limestone (1%) and salt (1%). In June 1994, sheep with complete pedigree records were hand-shorn prior to the breeding season. Previous shearing occurred annually. Body weight (BW) at shearing and greasy ¯eece weight (GFW) were individually measured for 20 male lambs (6±8month-old), 17 female lambs (6±10 months), 62 yearling ewes (14±20 months) and 235 mature ewes (28± 84 months). Samples of wool were obtained from the shoulder, right mid-side and hip of 12 male lambs, 10 female lambs, 27 ewe lambs and 82 mature ewes, randomly selected from the ¯ock. The wool sampling methods have been previously described (Tabbaa et al., 1998). The average staple length (SL) for each wool sample (in triplicates) was measured to the nearest 0.1 cm. Over 350 randomly drawn ®bers, were measured after washing with xylol, using a WIRA ®ber length testing machine. Again, 300 random ®ber samples from each location were measured using a projection microscope (Chapman, 1960). The average ®ber length (FL) and diameter (FD) of each sample as well as the ®ber diameter and the number of medullated ®bers (MF) were also measured (IWTO, 1952). The wool samples (0.2± 0.3 g) were manually separated into inner coat (ICF), outer coat (OCF) and kemp (KF) (Doney and Smith, 1961a). The weight of wool ®ber components in the sample was determined. Least squares procedures were used to analyze body weight, ¯eece weight, staple length, ®ber length and diameter, and percentage of medullated, inner coat, outer coat and kemp ®bers (Table 1). A general
Table 1 Least squares means (S.E.) of body and greasy ¯eece weights for Awassi sheep of different age±sex groupsa Age±sex group Male lambs Female lambs Yearling ewes Mature ewes ** a
N
20 17 62 235
Body weight (kg)
Greasy fleece weight (kg)
Greasy fleece weight (kg), adjusted for body weight
**
**
**
39 38 46 57
c 1.9 c 2.1 b 1.1 a 0.6
1.3 1.4 2.1 2.2
b 0.13 b 0.14 a 0.07 a 0.04
P < 0:01. Means within a column not followed by the same letter differ signi®cantly at P < 0:05.
1.5 1.7 2.2 2.1
b 0.13 b 0.14 a 0.07 a 0.04
M.J. Tabbaa et al. / Small Ruminant Research 41 (2001) 95±100
97
to vary among different age±sex groups and had an important in¯uence (P < 0:01) on greasy ¯eece weight with a regression of 17.8 g/kg. The remaining ¯eece characteristics were not signi®cantly affected by age±sex group, however, ®ber diameter tended to be lowest for male lambs and highest for female lambs. Again, the lowest percentage of medullated ®bers were found in female lambs. Concurrently, the percentage of kemp ®ber were lower in lambs than in older ewes (Table 2). The body location of the sample taken did not have a signi®cant effect on staple and ®ber length and percentage of outer coat ®bers. The ®ber diameter, and percentages of medullated, kemp and inner ®bers were signi®cantly affected by body location. The ®nest ®bers found on the shoulder and mid-side had a lower percentage of medullated ®bers than those from the hip. The percentage of kemp ®bers was lowest from the shoulder area while the percentage of inner coat ®bers was highest. Generally, ®bers on the mid-side were intermediate in their values between hip and shoulder, while the highest medullated ®bers were on the hip. None of the ¯eece characteristics studied were signi®cantly affected by the interaction between age±sex group and body location. In general, lambs had the longest ®bers on the shoulders and the shortest on the hip. However, older ewes had the longest ®bers over their mid-side and the shortest over their shoulders.
statistical model included the effect of age±sex group, sampling location, pooled linear regression on body weight, where applicable, and residual error (SAS, 1988). Tests of signi®cant differences among means were carried out using multiple range test. 3. Results The Awassi sheep weighing 53 0:6 kg produced 2:1 0:03 kg of greasy ¯eece weight. The body weight at shearing varied with age from 20 to 80 kg. The staple length, ®ber length and diameter were 14 0:18 cm, 24 0:26 cm and 36 0:3 mm, respectively. Concurrently, the percentage of medullated, inner and outer coat, and kemp ®bers were 12 0:3, 60 0:3, 34 0:2 and 6:3 0:16%, respectively. In this study, the highest percentage of inner coat ®bers with the lowest coef®cient of variation and a wider range of percent kemp ®ber was found. Age±sex group had a signi®cant effect on body weight, greasy ¯eece weight, staple and ®ber length (Tables 1 and 2). Although no signi®cant differences were observed between the lambs of both sexes, the greasy ¯eece weight (corrected for body weight) in male lambs was lower than those in female lambs and ewes. The greasy ¯eece weight (corrected for body weight) increased with age. Staple and ®ber length were highest for ewe lambs. The body weight tended
Table 2 Least squares means (S.E.) of various wool ®ber characteristics for Awassi sheep of different age±sex groups and body locationsa Age±sex group Male lambs Female lambs Yearling ewes Mature ewes Body location Shoulder Mid-side Hip a
N
36 30 81 246 131 131 131
Staple length (cm)
Fiber length (cm)
Fiber Medullated diameter (mm) fibers (%)
Inner coat fibers (%)
Outer coat fibers (%)
Kemp fibers (%)
**
**
11 c 0.7 13 bc 0.8 15 a 0. 15 ab 0.3 NS 14 0.3 14 0.3 14 0.3
20 c 1.0 22 bc 1.1 25 a 0.7 24 ab 0.4 NS 23 0.5 23 0.5 22 0.5
NS 34 36 36 36
NS 60 60 60 60
NS 34 35 33 34 NS 34 34 33
1.0 1.0 0.6 0.4
NS 5.8 5.5 6.8 6.3
0.4 0.4 0.4
4.7 a 0.3 6.5 b 0.3 7.3 b 0.3
**
1.6 1.8 1.1 0.6
34 a 0.5 34 a 0.5 38 b 0.5
NS 11 10 12 12 **
1.8 1.9 1.2 0.7
11 a 0.3 10 a 0.3 13 b 0.3
*
1.3 1.4 0.9 0.5
61 a 0.5 59 b 0.5 59 b 0.5
Means within a column not followed by the same letter differ signi®cantly at P < 0:05. NS (P > 0:05). P < 0:05. ** P < 0:01. *** P < 0:001. *
***
0.6 0.7 0.4 0.2
98
M.J. Tabbaa et al. / Small Ruminant Research 41 (2001) 95±100
4. Discussion The measurements of ¯eece characteristics in this study were in general agreement with those in the literature. In Awassi sheep, the greasy ¯eece weight range of 1.1±2.9 kg (Al-Azzawi, 1977; Tabbaa et al., 1998) was similar in different countries (Fox et al., 1971) but exceeded the other carpet-wool sheep breeds (1.9, 1.2 and 1.5 kg for the Arabi, Karadi and Hamadani breed, respectively) in the Middle East (Al-Azzawi, 1977). The wide range in ¯eece weight observed in this study re¯ects the large variation in the ages and weights of the animals possibly due to absence of selection for ¯eece characteristics in Jordan. Presently, sheep ¯eeces represent about 2.5% of the value of products from commercial Awassi sheep production (milk and meat) in Jordan (Campbell, 1996). This cannot be increased signi®cantly by increasing ¯eece weight since ¯eeces are mostly sold in number rather than weight. However, ¯eece characteristics may be more important in adding value to the product. The ®ber length of 24 cm in the present study is longer than 13±20 cm range in other Middle Eastern countries (Al-Azzawi, 1977). Interestingly only Awassi sheep in Turkey where most of the Jordanian ¯eeces are exported (Tabini, 1996) had comparable staple length (Yalcin, 1979). The ®ber diameter of Awassi sheep varies considerably from 27 to 55 mm (Al-Azzawi, 1977) and the present data falls within this range. The ®ber diameter of Awassi sheep are intermediate and comparable to carpet-wool breeds, 31 mm for Barki sheep (Seoudy et al., 1973), 26.2 mm for Arabi sheep (Ashmawi and El-Azzawy, 1980), 35.4 mm for Ossimi, and 31.5 mm for Rahmani (Marai et al., 1992). The 12% medullated ®bers in the present study was similar to that reported for Awassi ewes in Iraq (Al-Azzawi, 1977) and higher than those in the Arabi (10.9%), Ossimi (5.3%) and Rahmani (2.3%) breeds (Ashmawi and El-Azzawy, 1980; Marai et al., 1992). The ratios of types of ®ber in the ¯eece were similar to those obtained in other studies (Al-Azzawi, 1977). The Awassi sheep were reported to have the highest percentage of kemp ®ber among carpet-wool breeds (Arabi, Karadi and Hamadani) of the Middle East (Ashmawi and ElAzzawy, 1982). The large variation in percentage of kemp ®ber, an undesirable trait, however, demonstrate
opportunity for improving Awassi ¯eece quality by selection. Ashmawy and El-Azzawy (1980) did not ®nd any signi®cant effect of age on greasy ¯eece yield in Arabi sheep. In contrast, Al-Azzawi (1977) reported that ¯eece yield decreased with advancing age, whereas, Sidwell et al. (1971) found that ¯eece yield increased. In the present study, there was an increase in corrected greasy ¯eece weight from female lambs to yearling ewes, but no difference between yearling ewes and older ewes was detected. Again differences that existed between young female lambs and the older yearling ewes were not observed between yearlings and older females. A signi®cant effect of age on staple and ®ber length is in agreement with Sidwell et al. (1971) and Al-Azzawi (1977). In contrast to a signi®cant effect of age on the ®ber diameter of younger animals (Sidwell et al., 1971) and the Barki and Marino breeds, and their crosses in Egypt (Seoudy et al., 1973), there was no age effect on ®ber diameter in the present study, possibly because the animals were younger. In agreement with the present study, increasing age of Awassi and Arabi ewes in Iraq had no signi®cant effect on ®ber diameter (Al-Azzawi, 1977; Ashmawi and El-Azzawy, 1980). The percentage of medullated ®bers decreased with advancing age, contrary to the present ®ndings. There was no signi®cant effect of age of Arabi sheep for percentages of inner, outer coat and kemp ®bers (Ashmawy and El-Azzawy, 1980) in agreement with the ®ndings of the present study for percentage of inner ®ber. The percentages of inner coat and kemp ®bers in sheep of the Arabi, Karadi and Hamadani breeds (El-Azzawy, 1977), and the Awassi breed (ElAzzawy, 1977) were similar to those in the present study. However, the percentage of outer coat ®bers was the highest for 2-year-old ewes and decreased with age. Seoudy et al. (1973) also reported that the percentage of ®ne ®ber decreased with advancing age in Barki sheep. Though not signi®cant, lambs in general had a lower percentage of kemp ®ber than older ewes. Similarly, Martinez et al. (1997) reported that the percentage of kemp and medullated ®bers increased with age in ¯eece of llama. This is probably because the outer coat ®bers in lambs do not shed as kemp ®ber until lambs grow older. Therefore, the outer coat percentage was lower in lambs than in mature ewes.
M.J. Tabbaa et al. / Small Ruminant Research 41 (2001) 95±100
In contrast to this study, a highly signi®cant effect of body location on staple length in Blackface ewes (Doney and Smith, 1961b) and in Ossimi ewes (Saddick, 1993) has been reported. In Blackface sheep, the longest ®bers were found on the shoulder followed by the mid-side and the shortest ®bers were on the hip. Again, the mid-side in Ossimi sheep had the shortest staples among the three different locations sampled. The ®ber diameter found on the hip area was larger in the present study, in agreement with Doney and Smith (1961b) that the ®ber diameter of coarse ®bers of Blackface sheep was the largest on the hip out of nine locations sampled. Similar results were obtained by Saddick (1993) in Ossimi sheep and by Seoudy et al. (1973) in Merino and Barki ewes and their crosses. No clear trend of medullation of ®bers was noticed in the present study, although hip samples had the highest percentage. Saddick (1993) reported that percentages of medullated ®bers in Ossimi sheep were 9.9, 13.1 and 8.9 in the hip, mid-side, and shoulder, respectively. However, it is clear in the present study that body location signi®cantly in¯uence ®ber type percentages where the shoulder and mid-side had the highest percentages of inner coat ®bers and the lowest percentage of kemp. In Barki sheep the highest percentage of ®ne ®bers was also found on the shoulder (Seoudy et al., 1973). Al-Azzawi (1977), Ashmawy and El-Azzawy (1980), and Saddick (1993) indicated that lower medullation and smaller ®ber diameter were found on the shoulders and mid-side. In Blackface sheep on the other hand, higher percentages of ®ne ®bers were found on the shoulder and hip, but coarse ®bers were also found to be highest on the hip whilst kemp ®bers were highest on the shoulder (Doney and Smith, 1961b). It has been suggested that the mid-side area could be used in Ossimi sheep to represent the ¯eece characteristics of the animal as a whole (Saddick, 1993). In Jordan, Awassi sheep appeared to have longer ®bers, higher percentage medullated ®ber but similar ®ber diameter than those for the same breed in other countries. This may be because Awassi sheep in Jordan were not selected for ¯eece characteristics. The high ambient temperature and extremely low humidity under Jordan conditions may have contributed to the variation demonstrating potential for genetic improvement for desirable traits.
99
5. Conclusions The ¯eece of Awassi sheep can be divided into at least two parts of signi®cantly different qualities with potential for improvement. The shoulder area has a better ®ber quality than the mid-side and hip areas. Finer wool with lower medullation can be used for carpets with coarse wool used for ®lling mattresses and pillows during clip preparation. This would suggest an investigation into how much of the general variability in ¯eece quality is a result of differences in the relative size of areas of differing wool quality on the overall body area. This characteristic might be heritable and could promote breeding to increase the quantity of high quality wool. Acknowledgements The authors are grateful to ICARDA for helping in transporting the wool samples between Jordan and Iraq.
References Al-Azzawi, W.A., 1977. A comparative study of ¯eece characteristics in Iraqi sheep. M.Sc. Thesis. Cairo University, Faculty of Agriculture, Egypt, 112 pp. Ashmawi, G.M., El-Azzawy, W., 1980. Effect of age, locality and system of husbandry on ¯eece characteristics of Arabi sheep. Egyptian J. Anim. Prod. 20, 179±187. Ashmawi, G.M., El-Azzawy, W., 1982. A comparative study of ¯eece characteristics in Iraqi sheep. I. Greasy-¯eece weight, shrinkage % and ®ber type ratio. Egyptian J. Anim. Prod. 22, 53±61. Campbell, D.A., 1996. A review of animal production in the Badia. Population and Livestock related Studies in the Eastern Badia of Jordan, Workshop Report. The Jordan Badia Research and Development Program, Jubaiha, Amman, Jordan, pp. 81±87. Chapman, R.E., 1960. Measurements of wool samples. In: Fraser, A.S., Short, B.F. (Eds.), The Biology of the Fleece. Animal Research Laboratories, Technical Paper no. 3, Commonwealth Science and Industrial Research Organization, Sydney, pp. 71± 86. Doney, J.M., Smith, W.F., 1961a. The ¯eece of the Scottish Blackface sheep. I. Seasonal changes in wool production and ¯eece structure. Agric. Sci. 56, 365±374. Doney, J.M., Smith, W.F., 1961b. The ¯eece of the Scottish Blackface sheep. II. Variation in the ¯eece components over the body of the sheep. Agric. Sci. 56, 375±378.
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Fox, C., Chaaban, R., Hardison, W., Badawi, S., Choueiri, E., Maalouf, M., 1971. Selection and breeding programs of Awassi and Chios sheep, Vol. 36. Magon Publication, Lebanon, 45 pp. International Wool Textile Organization, 1952. The determination of wool ®ber thickness by a projection microscope. Draft speci®cation. Wool Sci. Rev. 8, 57. Marai, I.F.M., Gebriel, G.M., Abou-Fandoud, I., 1992. Relationships between blood groups and some wool characteristics in Egyptian coarse-wool fat-tail sheep. Anim. Prod. 55, 123±127. Martinez, Z., Iniguez, L.C., RodrõÂguez, T., 1997. In¯uence of effects on quality traits and relationships between traits of the llama ¯eece. Small Rumin. Res. 24, 203±212. Saddick, I.M., 1993. Variation in some wool characteristics over the body of Ossimi sheep, Meno®ya. J. Agric. Res. 18, 1143± 1155. SAS, 1988. SAS/STAT User's Guide, Release 6.03 Edition. SAS Institute Inc., Cary, NC, USA, 1028 pp.
Seoudy, A.M., Ghanem, Y.S., Ghoneim, K.E., 1973. Heterosis of wool characteristics in a cross between Merino and Barki sheep. II. Grease ¯eece weight, ®ber diameter, crimps, density and ®ber type ratio. Mesopotamia J. Agric. 8, 147±158. Sidwell, G.M., Wilson, R.L., Hourihan, M.E., 1971. Production in some pure breeds of sheep and their crosses. IV. Effect of crossbreeding on wool production. J. Anim. Sci. 32, 1099±1102. Tabbaa, M.J., Al-Azzawi, W.A., Al-Barakeh, F.S., 1998. Effect of age and sampling location on ¯eece and ®ber characteristics of Awassi sheep. Dirasat 25, 393±400. Tabini, R., 1996. Wool production and marketing. Population and Livestock related studies in the Eastern Badia of Jordan Workshop Report. The Jordan Badia Research and Development Programme, Jubaiha, Amman, Jordan, 25±34 pp. Yalcin, B.C., 1979. The sheep breeds of Afghanistan, Iran and Turkey. Food and Agriculture Organization of the United Nations, Rome, Italy, 159 pp.
Variation in ¯eece characteristics of Awassi sheep at different ages M.J. Tabbaaa,*, W.A. Al-Azzawib, D. Campbellc a
Department of Animal Production, University of Jordan, Amman, Jordan b IPA Agriculture Research Center, Baghdad, Iraq c DFID Livestock Project, P.O. Box 519, Jubaiha, Amman, Jordan Accepted 7 April 2001
Abstract Fleece characteristics have economic signi®cance in sheep. When assessing ®ber characteristics, the importance of sex, age of sheep and the body location of the sample taken are important considerations. Triplicate ¯eece samples were obtained from the shoulder, right mid-side and hip of 12 male and 17 female lambs (6±10 months), 62 yearling ewes (14±20 months) and 235 mature ewes (28±84 months) by hand shearing. The greasy ¯eece weight, staple length, ®ber length and ®ber diameter measures were 2:1 0:03 kg, 14 0:18 cm, 24 0:26 cm and 36 0:33 mm, respectively. Correspondingly, the medullated ®bers, inner coat, outer coat and kemp ®bers were 11:6 0:33, 59:7 0:29, 34:0 0:23 and 6:3 0:16%, respectively. Age had a signi®cant in¯uence on body weight and greasy ¯eece weight, but male and females were similar. Body location of the sample had a signi®cant effect on the ®ber diameter, and percentages of medullated ®bers, kemp ®bers, and inner coat ®bers. The ®nest ®bers and a lower percentage of medullated ®bers were found on the shoulder and mid-side, whereas, the percentage of inner coat ®bers was highest on the hip. Although there was no signi®cant interaction between body location and age±sex groups for ®ber characteristics, it was important for staple and ®ber length (P < 0:05). The wide variation in ®ber diameter and percentage of medullated ®bers suggest potential for improvement of economical traits. # 2001 Elsevier Science B.V. All rights reserved. Keywords: Wool; Fleece sampling; Fleece characteristics; Awassi sheep
1. Introduction The Awassi is a fat-tailed breed of sheep used for meat, milk and carpet-wool production. It is the most common breed in Jordan and in the Middle Eastern countries. The Awassi sheep produces good quality carpet (medium) wool. The price paid for the ¯eeces
*
Corresponding author. Tel.: 962-6-5355000/ext. 2578; fax: 962-6-5355577. E-mail address: [email protected] (M.J. Tabbaa).
is based on ¯eece characteristics, therefore, it is important to assess these traits and determine the potential for their improvement. Higher estimates of heritability have been reported for ¯eece characteristics in many breeds, therefore selection for desired traits might be useful. Furthermore, ¯eece characteristics in¯uence insulation values of the coat (Doney and Smith, 1961a) protecting the animal from the extremes heat and cold in Jordan. It has been reported that the body location of the wool samples taken in¯uences ¯eece characteristics (Doney and Smith, 1961b; Saddick, 1993; Seoudy et al., 1973; Tabbaa
0921-4488/01/$ ± see front matter # 2001 Elsevier Science B.V. All rights reserved. PII: S 0 9 2 1 - 4 4 8 8 ( 0 1 ) 0 0 2 0 3 - 6
96
M.J. Tabbaa et al. / Small Ruminant Research 41 (2001) 95±100
et al., 1998). Shoulder areas have longer, ®ner ®bers with a lower percentage of medullated ®bers than those from the mid-side and hip. Understanding the pattern of variation on the body would be useful in determining the most suitable sampling location for measuring ¯eece characteristics. There have been con¯icting reports in the literature regarding the effect of age on ¯eece characteristics. Sidwell et al. (1971) found greasy ¯eece weight increased with advancing age. In contrast, Al-Azzawi (1977) reported that ¯eece yield decreased with age. Again, Tabbaa et al. (1998) found negligible differences among ¯eece characteristics of mature Awassi ewes in Jordan. However, ¯eece characteristics of Awassi lambs have not been thoroughly investigated and compared with mature animals. Therefore, the objective was to study the ¯eece samples from various parts of the body of Awassi sheep of different ages. 2. Materials and methods The sheep ¯ock at the Jordan Ministry of Agriculture's Khanasri Animal Improvement Station in NE Jordan was assembled in the early 1970s from ewes collected from several farms, in various parts of Jordan. The rams were obtained from farmers in Jordan and Government Stations in Syria, Iraq and Turkey. The sheep were housed under a semi-intensive system with access to grazing from January to April, resulting in an intake of 18 MJ ME per day (Harb, personal communication). During the remainder of the year, 800 g of concentrate feed was provided to dry ewes. The feed supplement increased to 1.2 kg
concentrates and 0.3 kg hay during ¯ushing, lactation and the last 6 weeks of gestation. The concentrate consisted of barley grain (73%), wheat bran (15%), soybean meal (10%), limestone (1%) and salt (1%). In June 1994, sheep with complete pedigree records were hand-shorn prior to the breeding season. Previous shearing occurred annually. Body weight (BW) at shearing and greasy ¯eece weight (GFW) were individually measured for 20 male lambs (6±8month-old), 17 female lambs (6±10 months), 62 yearling ewes (14±20 months) and 235 mature ewes (28± 84 months). Samples of wool were obtained from the shoulder, right mid-side and hip of 12 male lambs, 10 female lambs, 27 ewe lambs and 82 mature ewes, randomly selected from the ¯ock. The wool sampling methods have been previously described (Tabbaa et al., 1998). The average staple length (SL) for each wool sample (in triplicates) was measured to the nearest 0.1 cm. Over 350 randomly drawn ®bers, were measured after washing with xylol, using a WIRA ®ber length testing machine. Again, 300 random ®ber samples from each location were measured using a projection microscope (Chapman, 1960). The average ®ber length (FL) and diameter (FD) of each sample as well as the ®ber diameter and the number of medullated ®bers (MF) were also measured (IWTO, 1952). The wool samples (0.2± 0.3 g) were manually separated into inner coat (ICF), outer coat (OCF) and kemp (KF) (Doney and Smith, 1961a). The weight of wool ®ber components in the sample was determined. Least squares procedures were used to analyze body weight, ¯eece weight, staple length, ®ber length and diameter, and percentage of medullated, inner coat, outer coat and kemp ®bers (Table 1). A general
Table 1 Least squares means (S.E.) of body and greasy ¯eece weights for Awassi sheep of different age±sex groupsa Age±sex group Male lambs Female lambs Yearling ewes Mature ewes ** a
N
20 17 62 235
Body weight (kg)
Greasy fleece weight (kg)
Greasy fleece weight (kg), adjusted for body weight
**
**
**
39 38 46 57
c 1.9 c 2.1 b 1.1 a 0.6
1.3 1.4 2.1 2.2
b 0.13 b 0.14 a 0.07 a 0.04
P < 0:01. Means within a column not followed by the same letter differ signi®cantly at P < 0:05.
1.5 1.7 2.2 2.1
b 0.13 b 0.14 a 0.07 a 0.04
M.J. Tabbaa et al. / Small Ruminant Research 41 (2001) 95±100
97
to vary among different age±sex groups and had an important in¯uence (P < 0:01) on greasy ¯eece weight with a regression of 17.8 g/kg. The remaining ¯eece characteristics were not signi®cantly affected by age±sex group, however, ®ber diameter tended to be lowest for male lambs and highest for female lambs. Again, the lowest percentage of medullated ®bers were found in female lambs. Concurrently, the percentage of kemp ®ber were lower in lambs than in older ewes (Table 2). The body location of the sample taken did not have a signi®cant effect on staple and ®ber length and percentage of outer coat ®bers. The ®ber diameter, and percentages of medullated, kemp and inner ®bers were signi®cantly affected by body location. The ®nest ®bers found on the shoulder and mid-side had a lower percentage of medullated ®bers than those from the hip. The percentage of kemp ®bers was lowest from the shoulder area while the percentage of inner coat ®bers was highest. Generally, ®bers on the mid-side were intermediate in their values between hip and shoulder, while the highest medullated ®bers were on the hip. None of the ¯eece characteristics studied were signi®cantly affected by the interaction between age±sex group and body location. In general, lambs had the longest ®bers on the shoulders and the shortest on the hip. However, older ewes had the longest ®bers over their mid-side and the shortest over their shoulders.
statistical model included the effect of age±sex group, sampling location, pooled linear regression on body weight, where applicable, and residual error (SAS, 1988). Tests of signi®cant differences among means were carried out using multiple range test. 3. Results The Awassi sheep weighing 53 0:6 kg produced 2:1 0:03 kg of greasy ¯eece weight. The body weight at shearing varied with age from 20 to 80 kg. The staple length, ®ber length and diameter were 14 0:18 cm, 24 0:26 cm and 36 0:3 mm, respectively. Concurrently, the percentage of medullated, inner and outer coat, and kemp ®bers were 12 0:3, 60 0:3, 34 0:2 and 6:3 0:16%, respectively. In this study, the highest percentage of inner coat ®bers with the lowest coef®cient of variation and a wider range of percent kemp ®ber was found. Age±sex group had a signi®cant effect on body weight, greasy ¯eece weight, staple and ®ber length (Tables 1 and 2). Although no signi®cant differences were observed between the lambs of both sexes, the greasy ¯eece weight (corrected for body weight) in male lambs was lower than those in female lambs and ewes. The greasy ¯eece weight (corrected for body weight) increased with age. Staple and ®ber length were highest for ewe lambs. The body weight tended
Table 2 Least squares means (S.E.) of various wool ®ber characteristics for Awassi sheep of different age±sex groups and body locationsa Age±sex group Male lambs Female lambs Yearling ewes Mature ewes Body location Shoulder Mid-side Hip a
N
36 30 81 246 131 131 131
Staple length (cm)
Fiber length (cm)
Fiber Medullated diameter (mm) fibers (%)
Inner coat fibers (%)
Outer coat fibers (%)
Kemp fibers (%)
**
**
11 c 0.7 13 bc 0.8 15 a 0. 15 ab 0.3 NS 14 0.3 14 0.3 14 0.3
20 c 1.0 22 bc 1.1 25 a 0.7 24 ab 0.4 NS 23 0.5 23 0.5 22 0.5
NS 34 36 36 36
NS 60 60 60 60
NS 34 35 33 34 NS 34 34 33
1.0 1.0 0.6 0.4
NS 5.8 5.5 6.8 6.3
0.4 0.4 0.4
4.7 a 0.3 6.5 b 0.3 7.3 b 0.3
**
1.6 1.8 1.1 0.6
34 a 0.5 34 a 0.5 38 b 0.5
NS 11 10 12 12 **
1.8 1.9 1.2 0.7
11 a 0.3 10 a 0.3 13 b 0.3
*
1.3 1.4 0.9 0.5
61 a 0.5 59 b 0.5 59 b 0.5
Means within a column not followed by the same letter differ signi®cantly at P < 0:05. NS (P > 0:05). P < 0:05. ** P < 0:01. *** P < 0:001. *
***
0.6 0.7 0.4 0.2
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4. Discussion The measurements of ¯eece characteristics in this study were in general agreement with those in the literature. In Awassi sheep, the greasy ¯eece weight range of 1.1±2.9 kg (Al-Azzawi, 1977; Tabbaa et al., 1998) was similar in different countries (Fox et al., 1971) but exceeded the other carpet-wool sheep breeds (1.9, 1.2 and 1.5 kg for the Arabi, Karadi and Hamadani breed, respectively) in the Middle East (Al-Azzawi, 1977). The wide range in ¯eece weight observed in this study re¯ects the large variation in the ages and weights of the animals possibly due to absence of selection for ¯eece characteristics in Jordan. Presently, sheep ¯eeces represent about 2.5% of the value of products from commercial Awassi sheep production (milk and meat) in Jordan (Campbell, 1996). This cannot be increased signi®cantly by increasing ¯eece weight since ¯eeces are mostly sold in number rather than weight. However, ¯eece characteristics may be more important in adding value to the product. The ®ber length of 24 cm in the present study is longer than 13±20 cm range in other Middle Eastern countries (Al-Azzawi, 1977). Interestingly only Awassi sheep in Turkey where most of the Jordanian ¯eeces are exported (Tabini, 1996) had comparable staple length (Yalcin, 1979). The ®ber diameter of Awassi sheep varies considerably from 27 to 55 mm (Al-Azzawi, 1977) and the present data falls within this range. The ®ber diameter of Awassi sheep are intermediate and comparable to carpet-wool breeds, 31 mm for Barki sheep (Seoudy et al., 1973), 26.2 mm for Arabi sheep (Ashmawi and El-Azzawy, 1980), 35.4 mm for Ossimi, and 31.5 mm for Rahmani (Marai et al., 1992). The 12% medullated ®bers in the present study was similar to that reported for Awassi ewes in Iraq (Al-Azzawi, 1977) and higher than those in the Arabi (10.9%), Ossimi (5.3%) and Rahmani (2.3%) breeds (Ashmawi and El-Azzawy, 1980; Marai et al., 1992). The ratios of types of ®ber in the ¯eece were similar to those obtained in other studies (Al-Azzawi, 1977). The Awassi sheep were reported to have the highest percentage of kemp ®ber among carpet-wool breeds (Arabi, Karadi and Hamadani) of the Middle East (Ashmawi and ElAzzawy, 1982). The large variation in percentage of kemp ®ber, an undesirable trait, however, demonstrate
opportunity for improving Awassi ¯eece quality by selection. Ashmawy and El-Azzawy (1980) did not ®nd any signi®cant effect of age on greasy ¯eece yield in Arabi sheep. In contrast, Al-Azzawi (1977) reported that ¯eece yield decreased with advancing age, whereas, Sidwell et al. (1971) found that ¯eece yield increased. In the present study, there was an increase in corrected greasy ¯eece weight from female lambs to yearling ewes, but no difference between yearling ewes and older ewes was detected. Again differences that existed between young female lambs and the older yearling ewes were not observed between yearlings and older females. A signi®cant effect of age on staple and ®ber length is in agreement with Sidwell et al. (1971) and Al-Azzawi (1977). In contrast to a signi®cant effect of age on the ®ber diameter of younger animals (Sidwell et al., 1971) and the Barki and Marino breeds, and their crosses in Egypt (Seoudy et al., 1973), there was no age effect on ®ber diameter in the present study, possibly because the animals were younger. In agreement with the present study, increasing age of Awassi and Arabi ewes in Iraq had no signi®cant effect on ®ber diameter (Al-Azzawi, 1977; Ashmawi and El-Azzawy, 1980). The percentage of medullated ®bers decreased with advancing age, contrary to the present ®ndings. There was no signi®cant effect of age of Arabi sheep for percentages of inner, outer coat and kemp ®bers (Ashmawy and El-Azzawy, 1980) in agreement with the ®ndings of the present study for percentage of inner ®ber. The percentages of inner coat and kemp ®bers in sheep of the Arabi, Karadi and Hamadani breeds (El-Azzawy, 1977), and the Awassi breed (ElAzzawy, 1977) were similar to those in the present study. However, the percentage of outer coat ®bers was the highest for 2-year-old ewes and decreased with age. Seoudy et al. (1973) also reported that the percentage of ®ne ®ber decreased with advancing age in Barki sheep. Though not signi®cant, lambs in general had a lower percentage of kemp ®ber than older ewes. Similarly, Martinez et al. (1997) reported that the percentage of kemp and medullated ®bers increased with age in ¯eece of llama. This is probably because the outer coat ®bers in lambs do not shed as kemp ®ber until lambs grow older. Therefore, the outer coat percentage was lower in lambs than in mature ewes.
M.J. Tabbaa et al. / Small Ruminant Research 41 (2001) 95±100
In contrast to this study, a highly signi®cant effect of body location on staple length in Blackface ewes (Doney and Smith, 1961b) and in Ossimi ewes (Saddick, 1993) has been reported. In Blackface sheep, the longest ®bers were found on the shoulder followed by the mid-side and the shortest ®bers were on the hip. Again, the mid-side in Ossimi sheep had the shortest staples among the three different locations sampled. The ®ber diameter found on the hip area was larger in the present study, in agreement with Doney and Smith (1961b) that the ®ber diameter of coarse ®bers of Blackface sheep was the largest on the hip out of nine locations sampled. Similar results were obtained by Saddick (1993) in Ossimi sheep and by Seoudy et al. (1973) in Merino and Barki ewes and their crosses. No clear trend of medullation of ®bers was noticed in the present study, although hip samples had the highest percentage. Saddick (1993) reported that percentages of medullated ®bers in Ossimi sheep were 9.9, 13.1 and 8.9 in the hip, mid-side, and shoulder, respectively. However, it is clear in the present study that body location signi®cantly in¯uence ®ber type percentages where the shoulder and mid-side had the highest percentages of inner coat ®bers and the lowest percentage of kemp. In Barki sheep the highest percentage of ®ne ®bers was also found on the shoulder (Seoudy et al., 1973). Al-Azzawi (1977), Ashmawy and El-Azzawy (1980), and Saddick (1993) indicated that lower medullation and smaller ®ber diameter were found on the shoulders and mid-side. In Blackface sheep on the other hand, higher percentages of ®ne ®bers were found on the shoulder and hip, but coarse ®bers were also found to be highest on the hip whilst kemp ®bers were highest on the shoulder (Doney and Smith, 1961b). It has been suggested that the mid-side area could be used in Ossimi sheep to represent the ¯eece characteristics of the animal as a whole (Saddick, 1993). In Jordan, Awassi sheep appeared to have longer ®bers, higher percentage medullated ®ber but similar ®ber diameter than those for the same breed in other countries. This may be because Awassi sheep in Jordan were not selected for ¯eece characteristics. The high ambient temperature and extremely low humidity under Jordan conditions may have contributed to the variation demonstrating potential for genetic improvement for desirable traits.
99
5. Conclusions The ¯eece of Awassi sheep can be divided into at least two parts of signi®cantly different qualities with potential for improvement. The shoulder area has a better ®ber quality than the mid-side and hip areas. Finer wool with lower medullation can be used for carpets with coarse wool used for ®lling mattresses and pillows during clip preparation. This would suggest an investigation into how much of the general variability in ¯eece quality is a result of differences in the relative size of areas of differing wool quality on the overall body area. This characteristic might be heritable and could promote breeding to increase the quantity of high quality wool. Acknowledgements The authors are grateful to ICARDA for helping in transporting the wool samples between Jordan and Iraq.
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