The effects of docking on performance and carcass characteristics of male Karakas lambs

 

 

Ö. Gökdal^I, ; T. Aygün^II; M. Bingöl^II; F. Karakus^II

^IAdnan Menderes Üniversitesi, Cine Meslek Yüksekokulu, 09500, Cine, Aydin, Turkey
^IIYüzüncü Yil Üniversitesi, Ziraat Fakültesi Zootekni Bölümü, 65080, Van, Turkey

 

 

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ABSTRACT

The effects of tail docking on growth performance and carcass characteristics of fat-tailed male Karakas, lambs were investigated. A total of 23 Karakas, single-born male lambs was used in this study. Nine were docked at one day of age using rubber elastrator rings and the rest was left intact. After weaning, the lambs were fed a finishing diet for 70 days, and then slaughtered to evaluate carcass characteristics. Total weight gains during the finishing period were 14.3 ± 1.00 and 18.9 ± 0.82 kg and average daily live weight gains 204.7 ± 14.41 and 269.9 ± 11.72 g for the undocked the docked group, respectively. The carcasses of the docked group contained more kidney, pelvic and internal fat than the intact lambs as well as a higher percentage of subcutaneous and intramuscular fat. The weights of the different carcass cuts of the docked lambs were also heavier that those of the intact group. The results indicated that the tail docking of fat-tailed Karakas lambs improved weight gain and desirable carcass characteristics compared to those of undocked lambs.

Keywords: Karakas lambs, fat tail docking, growth performances, slaughter

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Introduction

Meat production from sheep has retained its importance for centuries in the economy as well as its role in human nutrition in Turkey. Mutton makes an important contribution to red meat production, amounting to 26% of the total meat production in Turkey (Anon, 2000). However, the present meat production performances of native sheep breeds are far from optimal. The traditional extensive production methods, poor environmental conditions, economic limitations, lack of organisations among producers and genotypic characteristics of sheep are restrictive factors for optimum production. Native breeds comprise 96% of the sheep population of the country, whereas pure Merino and its crosses comprise only 4%. Approximately 87% of the sheep population in Turkey consists of fat-tailed breeds.

The fat-tailed Karakas sheep, a subtype of the Akkaraman sheep breed, is favourably characterised by its adaptation to harsh environmental and feeding conditions. The Karakas sheep are found in the Van and various deposits which alter markedly during growth (Negussie 2003). The fat deposited in the tail is considered as an energy source for the fat-tailed sheep during the times of low energy intake (O'Donovan ., 1973; Biyikoglu ., 1977). However, the fat tail of the breed is considered a liability in terms of reproduction, growth and feedlot performance and carcass marketing conditions. In addition, the fat deposition in the body or tail requires more energy than the deposition of lean tissue. Cengiz & Arik (1994) reported that in fat-tailed sheep breeds, the effect of docking on conversion rate of concentrates into meat tissue was more efficient than into fat tissue.

Numerous breeds of sheep and a diversity of production systems produce a wide variety of carcasses to satisfy different consumer requirements on the international market. For commercial reasons and because of consumer demand there is a need to reduce the tail fat part of fat-tailed sheep carcasses in Turkey. Consumers prefer fatter meat where the fat is distributed between the meat fibres. In addition, it is becoming more difficult to market excessively large tailed carcasses. The carcasses of fat-tailed sheep breeds are marketed with intact fat tails in Turkey. The presence of fat tails lowers the desirability of the carcass to the consumer and consequently the commercial value of the carcass. In addition, the consumer prefers fat dispersed throughout the meat fibres rather than as tail fat. Therefore, for consumers in Turkey, tail docking is one of the methods of producing delicious and desirable carcass from fat-tailed breeds. The practice of docking lambs by various methods is used in order to obtain preferred products. Tails are removed using a knife, rubber elastrator ring or the hot tail docking iron. Peers (2002) reported that docking of lambs by rubber elastrator rings was associated with less pain than other methods.

The objectives of docking fat tails in lambs are to improve meat quality, increase feed efficiency, improve live weight gain and to facilitate natural mating with non-fat-tailed breeds (Gürsoy & Özcan, 1982; Cengiz & Arik, 1994; Karakus & Cengiz, 2001; Pollard ., 2001). Although the studies referring to the docking of lambs of the fat-tailed sheep breeds showed various effects on the growth rate, carcass characteristics and fat deposition over the body, the majority found that docking of lambs improves the live weight gain in fattening, feed efficiency and carcass characteristics (Gürsoy & Özcan, 1982; Cengiz & Arik, 1994; Karakus & Cengiz, 2001; Bingöl ., 2002).

The objective of the study was to evaluate the effects of docking on finishing performance and carcass characteristics of fat-tailed male Karakas lambs.

 

Materials and Methods

A total of 23 fat-tailed Karakas single-born male lambs was used in the study. They were raised at the Research and Practice Farm, Department of Animal Science, Yüzüncü Yil University, Van, Turkey. Male Karakas lambs, born within a period of one week, were randomly assigned to two groups: docked (n = 9) and intact (control) (n = 14) lambs. The lambs in the "docked" group were docked at one day of age using rubber elastrator rings. The tails were removed after two weeks. All lambs were weaned at two months of age and placed on a finishing diet.

At the beginning of the finishing period, the live weights of all lambs (body weight at three consecutive days after weaning) were recorded. The animals were housed in groups according to treatment and were fed a concentrate mixture and 100 g clover hay/animal/day. The concentrate contained 90% dry matter and 168 g crude protein, 88.8 g crude ash and 98 g crude fat/kg feed. The hay contained 91.2% dry matter and 139 g crude protein and 375 g crude fibre/kg. The finishing period lasted for 70 days after which the lambs were slaughtered. Live weights of all animals were recorded every second week. Concentrate consumption of the groups was recorded. The finishing period lasted for 70 days after which the lambs were slaughtered. Final weights of all animals were recorded at three consecutive days after 12 h fasting and then after 24 h fasting prior to slaughter (Cengiz ., 1989; Elicin ., 1989; Ertugrul ., 1989). Concentrate consumption of the groups was recorded.

After complete eviceration and dressing, carcasses were weighed warm and again after being chilled for 24 h at +4 °C. The head, skin, feet, genitalia and offal were weighed. Internal fat deposited around the kidneys (perinephric fat) and around the gastrointestinal tract (gut fat) was dissected and weighed. The tail was removed at its articulation and the cannon bones were dissected from the carcass. The cold carcass was split along the backbone and carcass length, leg depth, leg width, leg length, rump width, chest depth, chest width and shoulder width were measured on the whole and left half of a carcass. The left half of the carcass was divided into six parts, according to the procedure of Colomer-Rocher . (1987) and weighed. The surface area of a cross section of the between the 12^th and 13^th rib was measured by tracing it onto acetate paper and measuring the area using a planimeter. Dressing percentage was calculated as a ratio of 24 h fasting weight prior to slaughter and cold carcass weight. Proportional weights were calculated as the ratio of the heart, lungs and liver weights relative to slaughter weight. The proportional weights of the testes and internal fat were calculated relative to warm carcass weight and those of the other organs and carcass cuts relative to the cold carcass weight, according to the procedure of Cengiz . (1989). The proportion of the muscle, bone and fat in the carcass was estimated by physical dissection and weighing of these tissues in the rib area between the 6^th and 12^th rib (More-O'Ferrall & Timon, 1977).

The mathematical model included fixed effect due to group and random effect due to residual error (SAS, 1998). The growth performance, live weight and various carcass characteristics were assessed. The Student's t-test was used to detect significant differences between means. Daily feed consumption and feed conversion efficiency were calculated on a group basis.

 

Results and Discussion

Growth performances during the finishing period of the intact and docked lambs are given in Figure 1.

 

 

The docked lambs had higher growth rates than the intact animals (Figure 1). Growth performance and mean feed consumption of groups during the finishing period are presented in Table 1. Total and daily weight gains during the finishing period were higher (P < 0.01) in docked lambs compared to control lambs. Similarly, the final live weights of docked animals at the end of the finishing period tended to be higher than that of the control animals (P > 0.05). These findings are consistent with those of Cengiz & Arik (1994) who found that the final weights and total and daily weight gains in docked lambs were higher than intact lambs. However, Alkass . (1985) and Marai . (1987) found no differences in growth performance between undocked and docked Awassi and Ossimi male lambs, respectively.

 

 

Feed conversion efficiency (the concentrate consumption per kilogram live weight gain) and daily concentrate consumption of the two groups were similar. Other studies with different sheep breeds found that docking did not affect feed efficiency (Gürsoy & Özcan, 1982; Bicer, 1988; Cengiz & Arik, 1994).

Carcass measurements of the two groups of lambs are presented in Table 2. Except for chest width and rump width, there were no differences in carcass measurements between the two groups. The values of chest width and rump width were higher in the docked than in the control lambs (P < 0.01 and P < 0.05, respectively). An indirect increase in carcass measurements in response to docking has been reported previously (Biyikoglu ., 1977; Cengiz & Arik, 1994). However, the effect of docking on carcass measurements is not well documented. In general, all carcass measurements of docked animals tended to be higher than those of the intact lambs, with the exception of the cross section of the , though the means of the groups did not differ (P > 0.05). In contrast, it has been reported in studies on other fat-tailed sheep breeds that the area was positively affected by docking (Marai ., 1987; Bicer, 1988; Gürsoy ., 1992; Cengiz & Arik, 1994). In the current study there were no differences (P > 0.05) in fat thickness over the area (Table 2).

Slaughter and carcass characteristics of the two groups of lambs are presented in Table 2. Slaughter weight, warm carcass weight, cold carcass weight and dressing percentage of docked lambs tended to be higher than in the control lambs, although the differences were not significant (P > 0.05). Marai . (1987) reported significant increases in slaughter weight, carcass weight and dressing percentage in docked compared to their intact control lambs. The untailed cold carcass weight of the docked group was higher (P < 0.01) than that of the intact lambs, in agreement with the findings of Cengiz & Arık (1994). The untailed dressing percentages of docked lambs were higher than those of the control lambs (P < 0.01). These results are in agreement with those of Cengiz & Arık (1994) and Bingöl . (2002) who found that docking reduced the proportion of tail fat significantly and increased the market prices of the carcass compared to intact fat-tail lambs. The reason for the high untailed dressing percentage of docked lambs seems to be that more fat was distributed between meat fibres in this group than in the fat tailed group. This is desirable from the point of view of consumers' demand and thus for commercial reason.

In the present study docking did not have any effect (P > 0.05) on the weights of the heads, four feet, skins, testes, kidneys and spleens of the lambs. However, heart, lungs and liver weights were higher (P < 0.05) in the docked than in the control lambs (Table 2). Similar results have been reported by Akkaraman (Cengiz & Arık, 1994) and Norduz lambs (Bingöl ., 2002). The carcasses of the docked lambs had more (P < 0.01) kidney, pelvic and internal fat than those of the control lambs. However, tail weights were higher (P < 0.01) in control lambs than in docked lambs, and the amount of kidney, pelvic and internal fat in the docked lambs was too low to affect carcass yield compared to the weight of the tail fat.

The wholesale cuts of the left half of the carcasses are presented in Table 2. The leg weight, back-loin weights, neck weight, flank-chest weights (P < 0.01), forearm weight (P < 0.05) were higher in docked than in the control group. The higher body and carcass weights were the indirect result of docking, due to higher growth rates in this group than in the control group. It has been reported that docking of fat-tails increased the weights of valuable wholesale cuts in the carcass of fat-tailed sheep breeds (Bıyıkoğlu ., 1977; Marai ., 1987; Biçer, 1988; Gürsoy ., 1992; Bingöl ., 2002). Proportional yields of wholesale cuts of carcass and organs are presented in Table 3.

 

 

There were significant differences in proportional yields of kidney and pelvic fat, internal fat, tail, back-loin and flank-chest between the two groups. Except for the tail, these measures were higher (P < 0.01) in the docked than in the control group. An increase in fat around internal organs in response to docking and a decrease in the tail fat portion have been reported by Bıyıkoğlu . (1977), Cengiz & Arık (1994) and Bingöl . (2002). The results of the present study are in agreement with the report by Cengiz & Arık (1994) that docking reduced the amount of total fat in a lamb's body. Muscle, bone and fat components of the carcasses assessed from the 6^th and 12^th rib cut of control and docked Karakas lambs are presented in Table 4.

Estimated from the 6^th-12^th rib cut, the docked lambs contained a lower proportion of bone (P < 0.05) and a higher proportion of subcutaneous fat (P < 0.01) and intramuscular fat (P < 0.05) than the intact lambs. Since intramuscular fat increases the taste of meat, consumers prefer carcasses with the fat distributed between the meat fibres. These results indicated that docking seems to be beneficial in complying with consumers' demands, though the docked group had a lower (P > 0.05) percentage of muscle than the control group. Similar results have been reported in Akkaraman lambs (Cengiz & Arik, 1994). Fat tail docking increased the percentage of intramuscular and subcutaneous fat in the carcass, and thus the total fat content of the lamb carcass, in agreement with Alkass . (1985), Bicer (1988), Bicer . (1992) and Cengiz & Arik (1994). These results are also in agreement with those of Demiruren . (1972), Gürsoy . (1992) and Cengiz & Arik (1994) who reported that carcasses of docked lambs tended to have a higher proportion of intramuscular and subcutaneous fat deposits and less tail fat than intact lambs and are thus more desirable to consumers. However, Biyikoglu . (1977) noted that docking age might affect the lean content of the carcass. In the present study animals that were docked at one day of age, produced desirable carcass characteristics, in agreement with results reported by Alkass . (1985), Bicer (1988), Bicer . (1992), Cengiz & Arik (1994) and Bingöl . (2002).

Despite the fact that different studies referring to the docking of fat-tailed lambs reported inconsistent effects on growth rate, the majority found that docking in lambs improves the live weight gain, feed efficiency and carcass quality. In this study, growth rates and carcass characteristics of Karakas lambs were more desirable in docked lambs than in undocked lambs.

 

Conclusions

The commercial value of lamb carcasses is determined by the proportion of the fat and muscle and by weight. Docked animals produced more desirable carcasses than untreated animals, indicating that docking of fat-tailed sheep breeds may be an effective way to improve growth rates and desirable carcass characteristics. All the fat was relocated in the carcass rather than in the tail of docked lambs. A carcass with better distribution of fat into the muscle fibres is preferred by the consumer. Docking of native fat-tailed breeds of Eastern Anatolia may be suggested to improve growth performance and desirable carcass characteristics.

 

Acknowledgements

The Research Fund of Yüzüncü Yil University supported this investigation financially.

 

References

Alkass, J.E., Rashid, N.H., Ali Íshak, M. & Talib H., 1985. The combined effects of docking and castration on growth rate and carcass characteristics of Awassi lambs. Wld Rev. Anim.Prod. 21, 49-52.         [ Links ]

Anonymous, 2000. Statistical Yearbook of Turkey. State Institute of Statistics. Prime Ministry Republic of Turkey, Ankara.         [ Links ]

Aygün, T., Demirel, M., Gökdal, Ö., ((elikyürek, H. & Kor, A., 1998. Farkli sürelerde sütten kesilen ve meraya ek olarak kesif yemle beslenen Karakas kuzularinin besi gücü ve karkas özellikleri Yüzüncü Yil Üniv. Zir. Fak., Tarim Bilimleri Derg. 8, 9-16.         [ Links ]

Biyikoglu, K., Cakir, A. & Yazgan, O., 1977. Dogu Anadolu'da Morkaraman koyunlarinda kuyruk kesiminin gelismeye, et verimine ve kalitesine etkileri Atatürk Üniv. Yay. 495, Zir.Fak.Yay. 232, Arastirma Serisi. 149, 40 pp. Yüzüncü Yil Üniv. Zir. Fak. Tarim Bilimleri Derg. 10, 1, 103-111.         [ Links ]

Gürsoy, O. & Özcan, L., 1982. Kuyruk köreltme ve kastrasyonun Ívesi kuzularinin gelismesine etkileri Yearbook, Vol. 13, 2. Cukurova Univ., Faculty of Agric. 49-63.         [ Links ]

Gürsoy, O., Özcan, L. & ve Pekel, E., 1992. Effects of castration and docking on carcass characteristics of Awassi lambs. Cukurova Üniv. Zir.Fak.Derg. 4, 4, 88-95. Karakus        [ Links ]

 

 

# Corresponding author. E-mail: ogokdal@yahoo.com