Growth performance and carcass characteristics of Awassi, Morkaraman and Tushin lambs grazed on pasture and supplemented with concentrate

Growth performance (n=T58) and carcass characteristics of 5 Awassi (A), 5 Morkaraman (M) and 4 Tushin (T) lambs weaned at 2.5 months of age were evaluated. The lambs were fed a concentrate mixture and allowed to graze for 70 days. At the end of the 70-day grazing period, M lambs showed the highest daily weight gain and the amount of concentrate consumed per body weight gain. The effects of breed and sex of lamb on daily weight gain on pasture were significant (P<0.05) and highly significant (PO.01) , respectively. Male lambs were superior to female lambs with respect to daily weight gain. Slaughter traits and carcass characteristics of 14 male lambs representing three fat-tailed breeds were compared at the end of the grazing period of the year in which they were born. Hot carcass weight and hindshank weight of M lambs were heavier than those of A and T lambs. M had higher hot dressing percentage and larger M. longissimus dorsi (LD) area than those of A and T lambs. Most of the weights of wholesale cuts were significantly (P<0.05; PO.01) affected by breed. It is recommended that either A, M and T male and female lambs weaned at 2.5 months of age in eastern Turkey should be fed with 450 g concentrate per head per day on pasture for 3 to 3.5 months of grazing season, or lambs should be supplemented with more than 450 g concentrate feed on pasture because native fat-tailed breeds supplemented with 450 g concentrate on pasture did not give carcasses with an adequate commercial weight in the 70-day fattening period.


INTRODUCTION
Approximately 87% of Turkey's sheep population (30.3 million heads) consists of fat-tailed breeds.Sheep meat (116.000tons) is an important contribution (22.5%) to red meat production in Turkey (Anonymous, 1997).On the other hand present GROWTH AND CARCASS TRAITS OF FAT-TAILED LAMBS meat production performances of native sheep breeds are far from meeting requirement (Bicer et al., 1992).
One of the factors affecting economical sheep meat production is higher growth and feed conversion efficiency of the material used.There are two alternatives for genetic improvement of lamb slaughter production with native sheep breeds.The first is pure breeding of indigenous breed; the second is crossbreeding with a mutton type sire breed to obtain maximum profit (Guney and Bicer, 1986).
Some studies on slaughter lamb production under intensive feeding conditions in Turkey have been performed (Guney and Bicer, 1986;Elicin et al., 1989a, b;Macit et al, 1997).Growth performance, slaughter and carcass characteristics of the indigenous breeds of eastern Turkey were studied by Bayindir (1980), Geliyi and Ilaslan (1984) and Aksoy (1994).Such information is essential in planning breeding programs to improve the amount of meat production and quality characteristics of carcasses of indigenous Turkish breeds.
The objective of this study is to evaluate growth performance, slaughter characteristics and carcass characteristics of several pure breeds raised under semiintensive management.

MATERIAL AND METHODS
The experiment was conducted at the Research and Application Farm of the College of Agriculture, Ataturk University, Erzurum, and involved 158 fat-tailed Awassi (A=94), Morkaraman (M=52) and Tushin (T=12) male and female lambs used to determine growth performance of fat-tailed breeds.The lambs were born in March 1998 and kept with their dams until approximately 2.5 months of age.At weaning they were weighed then divided into three treatment groups and subjected to semi-intensive feeding management.The concentrate mixture consisted of (%): barley, 42; maize, 24; soyabean meal, 10; wheat bran, 4; molasses, 8; limestone, 3; sunflower meal, 8; salt, 0.9; premix, 0.1.The concentrate had 88% DM, 16% crude protein (CP), 10% crude fat (CF) and 2500 Kcal ME per kg.Average daily ration of concentrate was 450 g as to feed basis per lamb during the grazing period on pasture.Primary forage plants of pasture wereFestuca ovina, Koleleria cristata, Bromus tomentalus, Medicago sp., and Onobrychis sp.The concentrate was fed to the lambs in the evening in an open-shed barn to house them during the night.
The concentrate consumption in addition to grazing on pasture and the liveweight of lambs were recorded biweekly.At the end of the 70-day fattening period, 5 A and 5 M, and 4 T male lambs whose weights were closest to the average final weight of male lambs were slaughtered for subsequent carcass analysis.
After slaughter, head, skin, feet and offal were removed and weighed.The carcasses were chilled at +4°C for 24 h before jointing and measurements taken on the intact cold carcass (Kempster et al., 1982).The fat tail was removed from each carcass prior to cutting into wholesale cuts (Figure 1) according to American Standards (Anonymous, 1973).The wholesale cuts including fat tail were weighed and recorded.Measurements included fat thickness over theM longissimus dorsi (LD), quantity of kidney and pelvic fat and LD area.The statistical analysis was conducted using the GLM procedure of SAS (1985).The data on growth performance were analyzed by a mathematical model which included the effects of breed (A, M, T), sex and type of birth (single and twin) of the lambs.Not all of the interactions investigated in this study were included in the model because they were non-significant.Significant differences between means with respect to growth performance were tested using Duncan's multiple range tests (Duncan, 1955).The data concerning the non-carcass components and carcass characteristics were analyzed by another linear model including only the effect of breed.

Daily weight gain and concentrate intake per kg weight gain on pasture
The effect of breed on daily weight gain (Table 1) was significant (P<0.05); the difference between M and T lamb groups was found to be significant (P<0.05).The results obtained from this study on daily weight gain for A, M and T lambs are in agreement with results of Buyukburc et al. (1983) of 166 g for Akkaraman lambs subjected to semi-intensive feeding on pasture, and Elicin et al. (1989c) of 169 g for Tushin male lams fed 500 g concentrate per head per day and grazed on pasture.The amount of concentrate consumed in addition to grazing on pasture on dry matter basis per kilogram of body weight gain averaged 2.5 kg for A, 2.3 kg for M and 2.7 kg for T lambs, respectively.
The sex of the lamb had a highly significant (P<0.01)effect on daily weight gain.Male lambs were heavier (P<0.01)than female lambs.They also had faster growth than females on pasture.Such differences have been well documented by a number of other investigators (Mavrogenis, 1996;Analla et al., 1998;Dolaksaribu et al., 2000;Macit et al., 2001).The effect of type of birth on daily weight gain was not significant on pasture (P>0.05).The data obtained from this study on daily weight gain is in agreement with result of Macit et al. (2001).

Slaughter characteristics
Slaughter weights of lambs were not affected by the breed of lambs (Table 2).The cold carcass weight for T lambs was significantly (P<0.05)lighter than that of M lambs.Similarly, T and A lambs had lower hot dressing percentage including tail fat than that of M lambs.T lambs had significantly lower (P<0.05)liver weight than that of M lambs.The dressing percentages obtained in this study for A, M and T lambs are similar to findings of Okuyan (1976) and Akcapmar (1981) who found a range in values from 49.60 to 53.20% for fat-tailed Akkaraman lambs, and Bicer et al. (1995) who reported a dressing percentage of 48.7% for Awassi male lambs.Aksoy (1994) indicated that cold dressing percentage in Morkaraman male lambs slaughtered at 40 kg liveweight was 50%.Also, the hot and cold dressing percentages in Tushin lams slaughtered at 42.8 kg weight were found to be 49.5 and 48.4% by Macit et al. (1997).

Carcass characteristics
Most of the cold carcass measurements (Table 3) except for carcass length and internal length of gigot were affected by breed of lamb.M lambs had significantly higher (P<0.01)width of gigot and heart girth measurements than those of A and T lambs.In addition, thoracic+lumber length and depth of gigot measurements for M lambs were found to be higher than those of T lambs.
The average weights of wholesale cuts of carcass weight with tail fat are presented in Table 4.A lambs had significantly higher (P<0.05)sirloin weight, rib weight than T lambs.However, the weight of hindshank cuts of A and T lambs was significantly lower (P<0.05)than in M lambs.M lambs had significantly higher (P<0.05;P<0.01) weight of leg, foreshank and breast, rib and hindshank cuts than ab means in rows with different superscripts are significantly different at P<0.05 or P<0.01 T The other differences among lamb breeds for the average weight of carcass cuts were not significant.Significant differences among indigenous breeds reared in Turkey in terms of weights of wholesale cuts were reported by Geliyi and Ilaslan (1984), Aksoy (1994) and Macit et al. (1997).
The LD area and the average fat thickness over LD muscle indicated no significant differences among breeds (Table 4).The LD area of M lambs was larger than those of A and T lambs.This may be expected because the slaughter weight of M lambs was higher than that of A and T lambs.The mean values of fat thickness over LD area for M, A and T lambs were lower than those reported by Macit et al. (1997) for Tushin male lambs slaughtered at 42.8 kg and Biger et al. (1995) for Awassi male lambs slaughtered at 40 kg.Also, Bayindir (1980) suggested that LD area and fat thickness over LD was significantly and positively correlated with slaughter weight, and it increased as slaughter weight increased.In addition, the proportion of fat in the carcass increases while that of bone and lean decreases with increasing slaughter weight.In terms of consumer and producer preferences, the optimum slaughter weight for native fat-tailed breeds under grazing with concentrate was reported to be 38-40 kg by Elicin et al. (1989c).
The average weight of wholesales cuts as proportions of cold carcass weight including tail fat are presented in Table 5.A lambs had a significantly higher (PO.05) proportion of sirloin than M lambs.In addition, the proportion of loin cuts of T lambs GROWTH AND CARCASS TRAITS OF FAT-TAILED LAMBS was significantly higher (P<0.05)than in M lambs.The other differences among lamb breeds for proportional weight of carcass cuts were not significant.
In general, the results obtained from this study revealed that M lambs excelled over A and T lambs reared in eastern Turkey in daily weight gain, concentrate feed consumption in addition to pasture per liveweight gain and the proportion of hindshank cuts in carcass characteristics.Male lambs were superior to female lambs with respect to daily weight gain and the amount of concentrate consumption in addition to grazing on pasture per kilogram weight gain.

CONCLUSIONS
As a result, it is recommended that either A, M and T male and female lambs weaned at 2.5 months of age in eastern Turkey should be fed with 450 g concentrate per head per day on pasture for 3 to 3.5 months of the grazing season, or lambs should be supplemented with more than 450 g concentrate on pasture because native fat-tailed Turkish breeds supplemented with 450 g concentrate on pasture did not give carcasses with an adequate commercial weight at the end of the 70-day of fattening period.

Figure 1 .
Figure 1.Wholesale cuts of lamb carcass

TABLE 1
Least squares means (±SE) for fattening performance traits of fat-tailed Awassi, Morkaraman and Tushin lambs ab means in rows with different superscripts are significantly different at P<0.05 or P<0.01

TABLE
Least squares means (±SE) for weight of slaughter and non-carcass components from three fat-tailed sheep breeds in Turkey

TABLE 3
Least squares means (±SE) for carcass measurement of various fat-tailed sheep breeds

TABLE 5
ab means in rows with different superscripts are significantly different at P<0.05 or P<0.01