The effect of breed slaughter weight and nutritional management
on cholesterol content of lamb carcasses
G. Arsenos
a,*, D. Zygoyjannis
b, D. Ku®dis
c, N. Katsaounis
b, C. Stamataris
b aDepartment of Management and Health, Animal Biology Division, Scottish Agricultural College, Bush-Estate, Penicuik,EH26 OPH, Scotland, UK
bDepartment of Animal Husbandry, Faculty of Veterinary Medicine, Aristotle University, 54006 Thessaloniki, Macedonia, Greece cLaboratory of Animal Nutrition, Faculty of Veterinary Medicine, Aristotle University, 54006 Thessaloniki, Macedonia, Greece
Accepted 11 August 1999
Abstract
This study was carried out to assess the effect of breed, sex, post-weaning nutrition, live weight at slaughter and their interactions on the cholesterol content in carcass fat of lambs. The carcasses were obtained from lambs of three indigenous Greek dairy breeds of sheep, the Boutsko (B), Serres (S) and Karagouniko (K) breed. After weaning (at approximately 42 days), the lambs of the three breeds had been reared under different conditions of housing and nutritional management in three consecutive experiments between 1992 and 1994. In experiment 1, lambs (males and females) were individually penned and fed ad libitum on a concentrate ration (11.3 MJ Metabolizable Energy (ME)/kg DM and 192 g crude protein (CP)/kg DM) together with 100 g per day of Lucerne hay (8.3 MJ ME/kg DM and 182 g CP/kg DM). In experiment 2, lambs (males only) were also individually penned but were fed on three different levels of concentrate and ad libitum on Lucerne hay. In experiment 3, lambs (males only) were initially group fed indoors for 63 days on three different levels of concentrate together with ad libitum Lucerne hay, and thereafter the lambs ®nished on irrigated, sown pasture (Lolium perreneTrifolium repens). Lambs were assigned to be slaughtered at one of ®ve standard proportions of estimated mature weight for each breed in experiment 1; at three ®xed live weights, common for all breeds in experiment 2 and at two ®xed proportions of breed mature weight in experiment 3. The right-hand side of the lamb carcasses was minced and 150 lamb carcasses were selected out of a total of 300 minced carcasses. The concentration of total cholesterol content in carcass fat was determined by HPLC in samples of these 150 lamb carcasses. Mean cholesterol content of carcass fat in the three breeds, B, S and K, extracted from the whole ground carcasses samples, was 3.33, 4.41, 3.34 mg/g of carcass fat (s.e.d. 0.18), respectively in experiment 1, whereas this content was 3.42, 4.50, 3.59 mg/g of carcass fat (s.e.d. 0.19) in experiment 2 and 4.38, 3.47, 3.78 mg/g of carcass fat (s.e.d. 0.22) in experiment 3. Cholesterol content differed signi®cantly (P< 0.001 in experiments 1 and 2,P< 0.05 in experiment 3) between breeds. It was also signi®cantly affected (P< 0.05) by the sex of lambs (experiment 1). Live weight of lambs at slaughter had a signi®cant effect on cholesterol content (P< 0.001 in experiment 1 andP< 0.05 in experiment 2). There was a general trend for cholesterol content to be lower in fat samples extracted from carcasses as target slaughter weight increased. The different levels of concentrate feed affected signi®cantly (P< 0.00l) the cholesterol content in carcass fat in experiment 2. The results suggest that there are possibilities of modifying body composition by manipulation of post-weaning nutrition, especially reducing the cholesterol content, in carcass fat of lambs slaughtered at a wide range of live weights. In such a situation, however, as nutritional management and degree of maturity change, breed remains the main factor that determines the cholesterol content in carcass fat.#2000 Elsevier Science B.V. All rights reserved.
Keywords:Carcass fat; Lambs; Cholesterol content; Slaughter weight; Breeds
*Corresponding author. Tel.:44-131-5353200; fax:44-131-5353121.
E-mail address: g.arsenos@ed.sac.ac.uk (G. Arsenos)
1. Introduction
Despite the extended and continuous research on growth, development and meat production in sheep there is little information concerning the overall qual-ity of the ®nal product (Zygoyiannis et al., 1997). Cholesterol content in carcasses of meat producing animals has long been identi®ed as the single most important characteristic of overall meat quality (New-man, 1993). In view of the role of animal fats in human health, consumer's concerns are increasingly re¯ect-ing their awareness of the link between health and nutrition (Brewer, 1994). To our knowledge, most of the available information regarding the cholesterol content in carcass of lambs are hardly relevant to the consumer because pertinent studies have been focused mainly on the determination of cholesterol content either in individual muscles or in speci®c fat depots rather than in lamb carcasses as a whole (Honikel and Arneth, 1996).
The results described in this paper formed part of a wider series of studies, supported by the European Commission, designed to assess the quality and mar-ketability of sheep meat produced in the less favoured areas (LFA) of the community. Our objectives in the current study were: (i) to determine the content of total cholesterol in the carcass fat of lambs of three indigenous Greek dairy breeds of sheep, and (ii) to investigate whether the cholesterol content in carcass fat was affected by breed, sex, nutritional manage-ment and live weight (LW) at slaughter. More speci®cally, the following factors were examined: (i) breed, sex and degree of maturity at slaughter in experiment 1, (ii) breed, feeding treatment and slaughter weight in experiment 2 and (iii) breed, and slaughter weight of lambs reared under a different ®nishing treatment (grazing on irrigated pasture) in experiment 3.
2. Materials and methods
2.1. General experimental procedures
The experimental procedures regarding sample pre-paration and cholesterol determination were identical for all samples. Speci®c design and methods are detailed below.
2.1.1. Animals
The study was carried out by using 150 samples from lamb carcasses which were selected out of a total of 300 lambs that were used in three consecutive experiments (for details see Section 2.2). All the lambs were weaned at approximately 42 days. They belonged to three indigenous dairy breeds of sheep, which were chosen as representatives of the most common breeds of sheep in Greece. They were: the Boutsko breed (B), a mountain breed with an initially estimated mature weight of 50 and 38 kg for males and females respec-tively, the Serres breed (S), a lowland breed with an initially estimated mature weight of 60 kg for males and 50 kg for females and the Karagouniko breed (K), a lowland breed with an initially estimated mature weight of 70 kg for males and 55 kg for females.
2.1.2. Feeds
The same two feeds (concentrate and Lucerne hay) were used throughout the three experiments. The ingre-dients and chemical composition of these feeds are shown in Table 1. The concentrate feed was made into pellets (3 mm) and contained 192 g crude protein (CP) per kg of dry matter (DM) and 11.3 MJ Metabolizable Energy (ME)/kg DM. The Lucerne hay contained 182 g CP/kg DM and 8.3 MJ of ME/kg DM. The concentrate
Table 1
Ingredients and chemical composition of the experimental feeds Feeds
Concentrate Lucerne hay
Ingredients(g/kg)
Barley 542 ±
Maize 100 ±
Sugar beet pulp 135 ±
Soybean 200 ±
Salt 10 ±
Vitaminmineral premix 10 ±
NH4Cl 2.6 ±
Acid detergent fibre 106 312 Natural detergent fibre 246 250 Acid hydrolysed ether extract 28 ±
feed was formulated to be relatively high in CP content and was expected to support the potential growth of the animals when offered ad libitum (ARC, 1990).
2.1.3. Measurements
Lambs in all experiments were weighed at the start of each experiment and subsequently at 7-day intervals (every Monday). Those found to be approaching target live weight were then weighed daily until the nominated weight was recorded and were slaughtered on the same day. 6 h after slaughter the carcasses were refrigerated at18C and kept at this temperature until sampling.
2.1.4. Sampling procedures
The carcass samples (n150) used in this study, were selected (randomly within sub-classes) out of a total number of 300 minced half (1/2) carcasses cover-ing the whole range of the live weights achieved and the feeding treatments for the B, S, and K breeds respectively. The refrigerated carcasses were sawn down at the middle line through the centre of the vertebral column and the right-hand side (RHS) of each carcass was minced and thoroughly mixed. One random sub-sample, each of approximately 200 g was taken from each minced carcass and stored in a deep freezer (ÿ258C). All frozen samples were freeze-dried (Leybold-Heraus GT2) and were ground, in a small mill, to pass through a 1 mm mesh screen. From the ground samples, a quantity of 2 g was taken for lipid extraction.
2.1.5. Cholesterol determination
Concentration of total cholesterol in carcass fat was determined by HPLC using a modi®cation of the procedure suggested by Klatt et al. (1995). Total lipids from carcass samples were extracted and puri®ed according to the method of Folch et al. (1957). A quantity of approximately 100 mg (1 mg) of the puri®ed lipid was accurately weighed in a glass tube (40 ml capacity) equipped with a Te¯on coated screw-up. A 4 ml volume of 95% aqueous ethanol and 0.8 ml of a freshly prepared solution of KOH (50%) were added and the tube was sealed, well shaken in a vortex-type mixer and heated for 90 min in a water bath (508C). At 15 min intervals, the tube was shaken brie¯y using a vortex mixer. Immediately after the samples were removed from the water bath, 6 ml of aqueous (95%) ethanol were added and the tubes were
allowed to cool at room temperature. Subsequently, 10 ml of toluene and 11 ml of 1 N KOH solution were added and the tubes were shaken vigorously using the vortex for 2 min. The solution was then allowed to separate into two layers, the aqueous layer (bottom) was discarded and the organic (upper) layer was washed with 4 ml of 0.5 N KOH solution. The tubes were again shaken and allowed to stand until the separation of the two layers. If an emulsion was formed, a small amount of 1±2 ml of 95% ethanol was added to facilitate the separation of the layers. The bottom layer was again discarded whereas the upper one was washed successively three times with a total volume of 12 ml of distilled water. Afterwards, a small amount of anhydrous Na2SO4 was added to remove
traces of moisture and the tubes were centrifuged for 5 min. The whole amount of the upper layer was transferred carefully to a small ¯ask with a cover of Te¯on. The solvent was evaporated to dryness under a steam of nitrogen and the remaining dry residue was re-dissolved in an exact amount of 3 ml isopropanol-2. Sample solutions were then kept frozen (ÿ258C) until HPLC analysis. After thawing, an exact amount of 30ml from each sample was injected into the high performance liquid chromatograph (Perkin-Elmer, Series 3) equipped with a Rheodyne injection valve (170ml sample-loop), a 2504.6 mm column packed with 10mm Spherisorb C18, a UV absorbance detector
set at 214 nm and an integrator (Shimazu Chromato-pak C-R3A). The mobile phase was a mixture of isopropanol-2-acetonitrile; ACN 40/60) for the quan-titative determination of total cholesterol. Recoveries were determined by employing cholesterol calibration standard (SRM 911b, National Bureau of Standards, US Department of Commerce) which were run daily.
2.2. Speci®c experimental design
2.2.1. Experiment 1
function and avoid rumen acidosis. Lambs were slaughtered at one of ®ve standard proportions of estimated mature weight (PMW), i.e., 20%, 30%, 45%, 60% and 90%. The cholesterol determination was carried out by using only two carcass samples out of four minced carcasses of lambs of each breed and sex, slaughtered at each of the ®ve stages of PMW. These samples were selected at random, within the above sub-classes, to give a total of 60 samples.
2.2.2. Experiment 2
In this experiment, described in detail by Zygoyian-nis et al. (1999), 36 exclusively male lambs from each breed were used. The experimental work was carried out in individual pens at the same location (IRAI) as in experiment 1. The lambs were randomly allocated to 3-target slaughter live weights (TSLW), i.e., 23. 28 and 33 kg, common to all breeds. The TSLW were selected to correspond to the carcass weights at which the B, S and K lambs, respectively, were found to produce the most market acceptable carcasses from the results of experiment 1. Lambs were fed both Lucerne hay, which was offered ad libitum in speci®c designed metal troughs, and restricted amounts of concentrate. The concentrate allowances (CA) were offered daily at high (H), medium (M) and low (L) levels. The H level was set to correspond to 80% of the mean ad libitum intake as it was measured in experi-ment 1, whereas the M and L levels were set to 67% and 33% of the H level, respectively. The amounts offered were increased each week by feed quantities of 33, 22, 11 g in B, 48, 32, 16 g in S and 54, 36, 18 g in K lambs for the H, M and L level of CA respec-tively. The cholesterol determination was carried out by using only two carcass samples out of four minced carcasses of lambs from each breed, TSLW and CA. These samples were selected at random, within the above sub-classes, to give a total of 54 samples.
2.2.3. Experiment 3
In this experiment also reported by Zygoyiannis et al. (1999), only male lambs (24 from each breed) were used. The experiment consisted of two phases: an indoor phase that lasted 63 days and a grazing phase. During the indoor phase the design of the feeding treatments was similar to that used in experi-ment 2 and the levels of CA were derived from the intakes recorded in experiment 2. The maximum level
of CA (H) was set equal to the M level used in experi-ment 2 for both K and S lambs while for the B lambs, the H level was only 60% of the M level used in experiment 2. The M level for experiment 3 was intermediate between M and L levels used in experi-ment 2 for each breed. Finally the L level was set at a nominal 50 g per day for all breeds. Initial offerings were increased weekly by ®xed amounts. These CA were assigned to achieve three de®ned live weights for each breed prior to turnout to the grazing phase. Lambs were to be slaughtered off pasture when they attained one of two nominated PMW. These had been set at 48% and 54% of the mature weight for each breed. The irrigated, sown pasture consisted of tetra-ploid ryegrass (Lolium perenne) and white clover (Trifolium repens) in a proportion of 10 : 1, respec-tively. Pasture management was based on maintaining a relatively constant sward surface height throughout the grazing season using change in grazing area or adding of non-experimental lambs as required (mean 6 cm with a maximum tolerance of 2 cm). The lambs were slaughtered when they reached the de®ned PMW. The cholesterol determination was carried out by using only two carcass samples out of ®ve minced carcasses of lambs from each breed, CA and PMW. These samples were selected at random, within the above sub-classes, to give a total of 36 samples.
2.3. Statistical analyses
All statistical analyses were performed using Mini-tab statistical package (MiniMini-tab version 11). Data were analysed separately for each experiment using the general linear model (GLM). The model used account-ing for the main effects and interactions of breed, sex, degree of maturity (TSLW) in experiment 1, breed, CA, TSLW in experiment 2, and breed and PMW in experiment 3. The signi®cance of all main effects and interactions was tested against the error mean squares.
3. Results
3.1. Experiment 1
maturity (TSLW). This ®nding suggests that these two factors are of major importance in terms of cholesterol deposition (content) in carcass fat. Cholesterol content was also signi®cantly affected (P< 0.001) by the interaction between breed and TSLW (Table 2). Small but signi®cant differences (P< 0.05) were found between carcasses of male and female lambs. It is interesting to note the inverse proportional relation-ship between TSLW and cholesterol content. It seems that the mean cholesterol content decreased as the degree of maturity approached the mature weight of each breed. This pattern was consistent for all breeds. In general, the intermediate-sized breed S seemed to deposit the most cholesterol in carcass fat.
3.2. Experiment 2
Mean cholesterol values in respect of breed, PMW and CA are shown in Table 3. The results
suggest that diet restrictions can result in signi®cant changes in cholesterol content of carcass fat. Thus, as the proportion of CA decreased and that of Lucerne hay increased in the diet of lambs, the cholesterol content in their carcass fat increased (P< 0.001). Analysis of variance showed that breed had a signi®cant effect (P< 0.001) similar to that observed in experiment 1. The effect of PMW was also signi®cant (P< 0.05), but this signi®cance could be attributed to the fact that, although lambs were slaughtered at the same LW, their carcasses were at a different degree of maturity. Unlike experi-ment 1, there were no signi®cant interactions between any of the main factors. It is important to note that, generally, carcasses from lambs at the ®rst slaughter point had a higher cholesterol content in all breeds and that lambs fed on L levels of CA appeared to deposit more cholesterol than those fed on H levels.
Table 2
Mean cholesterol content (mg/g of carcass fat) of lamb carcasses by breed, sex and degree of maturity in experiment 1
Breed Sex Degree of maturity Overall means
20% 30% 45% 60% 90%
B Male 4.77 5.43 2.64 2.42 3.26 3.33
Female 4.05 4.85 2.22 1.96 1.77
S Male 5.06 7.33 4.33 3.23 3.45 4.41
Female 7.36 6.09 3.14 2.38 1.74
K Male 4.39 3.19 3.37 3.00 1.95 3.34
Female 5.49 3.96 4.17 2.38 1.55 Overall means 5.18 5.14 3.31 2.56 2.28 S.e.d. for comparing overall Breed means: 0.18
S.e.d. for comparing overall Degree of maturity means: 0.24 Overall sex means are: male, 3.85; female, 3.54; s.e.d., 0.15
Source of variation d.f. m.s. F-value P
Breed 2 7.63 22.44 ***
Sex 1 1.48 4.35 *
Degree of maturity 4 23.18 68.18 ***
BreedSex 2 1.62 4.76 *
BreedDegree of maturity 8 2.32 6.82 ***
SexDegree of maturity 4 1.77 5.21 **
BreedSexDegree of maturity 8 0.83 2.44 *
Error 30 0.34
Total 59
3.3. Experiment 3
Table 4 shows the mean values of the cholesterol content of carcass fat of lambs ®nished on irrigated pasture. Cholesterol content in carcass fat differed signiticantly (P< 0.01) between breeds. There was no apparent effect of dietary treatment during the indoor phase. This implies that the nutritional treat-ment before turnout to grazing appears to be of minor signi®cance. There was a slight indication of a decrease in cholesterol content in the carcasses of heavier lambs but the differences between PMW were non-signi®cant. However, there were small differ-ences between breeds when compared at the same PMW, with the B breed showing consistently higher values.
4. Discussion
This study was conducted to determine the choles-terol content in whole carcass fat of edible lamb meat by comparing results of three different systems of production. We discuss ®rst the effects of breed of lambs and subsequently the effects of sex since this factor was examined only in experiment 1. The effects of feeding treatment and live weight at slaughter, alternatively de®ned as proportion of mature weight are then addressed.
4.1. Effects of breed and sex
The results indicate that the effect of breed was apparent throughout the three experiments. Among
Table 3
Mean cholesterol content (mg/g of carcass fat) of lamb carcasses by breed target slaughter live weight (TSLW) and concentrate allowances (CA) in experiment 2
Breed TSLW Concentrate allowances Overall means
H M L
B 23 2.59 3.71 4.40 3.42
28 2.63 3.21 3.77
33 3.25 3.70 3.52
S 23 4.20 4.78 5.74 4.50
28 3.78 4.53 4.56
33 3.43 4.05 5.42
K 23 2.65 4.16 4.64 3.59
28 2.53 4.16 3.02
33 3.11 4.17 3.90
Overall means 3.13 4.05 4.33
S.e.d. for comparing overall Breed means: 0.19 S.e.d. for comparing overall CA means: 0.18
Overall means for the 23, 28 and 33 TSLW are: 4.10,3.57 and 3.84; s.e.d. 0.19, respectively
Sources of variation d.f. m.s. F-value P
Breed 2 6.04 19.48 ***
TSLW 2 1.22 3.94 *
CA 2 7.11 22.94 ***
BreedTSLW 4 0.17 0.55 NSa
BreedTSLW 4 0.52 1.68 NSa
TSLWCA 4 0.50 1.61 NSa
BreedTSLWCA 8 0.28 0.90 NSa
Error 26b 0.31
Total 52b
aNS: not signi®cant. bOne sample was missing. *P< 0.05.
the other factors that have been studied, breed seems to be the most important regarding the effects on carcass fat and its cholesterol content. This is in agreement with the results of other studies (Zygoyian-nis et al., 1992; Nurnberg et al., 1998; Matthes et al., 1998). The above was more evident from the results in experiment 3 in which, apart from breed factor, none of the others had any signi®cant effect. Similar ®nd-ings with our results were reported by Abutarboush and Dawood (1993), Sevi et al. (1997) and Demise et al. (1998). Reported values ranged from about 135 to 184 mg per 100 g adipose tissues. The results of the current study support the belief that the indigenous Greek breeds produce carcasses with better eating quality (Zygoyiannis et al., 1990; Arsenos, 1997), as far as its savour is concerned. They also suggest that there is a chance for the producers to choose between the breeds studied here in terms of cholesterol content in carcass fat, when attempts are made to improve the overall quality of lamb carcasses.
How-ever, there was no clear indication of a consistent difference between sex types within breeds (experi-ment 1) and it was not feasible to have a further indication on these effect as the following experiments were carried out with male only lambs.
4.2. Effects of nutritional management
In experiment 2, feeding treatment seems to be important when comparisons are made at similar carcass weights with respect to differences in the degree of maturity between breeds. The different levels of CA and that of Lucerne hay fed ad libitum resulted in increased amount of cholesterol content in carcass fat in response to reduction in the CA. The highest amounts were observed in breed S and the lowest in breed K. Mean cholesterol content was signi®cantly decreased due to H levels of CA in S and K breeds, but not in the slower maturing breed B. In contrast, results from carcasses of lambs fed
Table 4
Mean cholesterol content (mg/g of carcass fat) of lamb carcasses by breed, proportion of mature weight (PMW) and concentrate allowances (CA) in experiment 3
Breed PMW Concentrate allowances Overall means
1 2 3
B 0.48 3.31 5.01 5.07 4.38
0.55 4.36 3.90 4.66
S 0.48 4.55 3.53 3.25 3.47
0.55 2.89 2.96 3.67
K 0.48 3.56 3.68 4.40 3.78
0.55 4.04 3.72 3.30
Overall means 3.78 3.80 4.06
S.e.d. for comparing overall Breed means: 0.21 S.e.d. for comparing overall CA means: 0.21
Overall means for the 0.48 and 0.52 PMW are: 4.04, and 3.72; s.e.d. 0.19, respectively
Sources of variation d.f. m.s. F-value P
Breed 2 2.56 8.83 **
PMW 1 0.91 3.14 NSa
CA 2 0.28 0.97 NSa
BreedPMW 2 0.19 0.66 NSa
BreedCA 4 0.52 1.79 NSa
PMWCA 2 0.20 0.69 NSa
BreedPMWCA 4 1.39 4.79 **
Error 18 0.29
Total 35
on medium levels of CA were more similar across PMW.
The results, also, indicate that the cholesterol con-tent is lower in carcass fat samples obtained from lambs ®nished on pasture (under the present system, experiment 3) than those obtained from other lambs (of the same breed) which were reared indoors in individual pens on a diet of restricted amounts of CA and ad libitum Lucerne hay (experiment 2). As expected from the results in experiments 1 and 2, B lambs tended to contain higher levels of cholesterol in their carcass fat than those of the other two breeds. These lambs, were grazing for a shorter period of time since they belong to an early maturing breed. The results from experiment 3 suggest that, irrespectively of feeding treatment during indoor phase, increasing the duration of grazing period could improve the carcass quality of lambs. Zygoyiannis et al. (1999) suggested that grazing on irrigated pasture would allow reaching the optimal growth of muscles of fattening lambs. Thus, lambs reared on irrigated pas-ture could be a source of low-fat, low-cholesterol carcasses throughout the year. These observations support the belief that the slower rearing systems may result in a lower concentration of cholesterol in carcass fat at equivalent weights (Demise et al., 1998) and may also help to explain the decrease in fat content in carcasses of grazing lambs (Sanudo et al., 1996). However, Solomon et al. (1992), found that diet had no effect on cholesterol content of lean tissue and Rule et al. (1997) suggested that different growing-®nishing strategies in beef cattle production systems did not alter cholesterol in meat. Nevertheless, great variability in cholesterol content was reported by Park et al. (1991) in carcasses from post-weaned kids fed a high quality concentrate diets and by Lough et al. (1993) in various fat depots of lambs fed forage diets.
4.3. Effects of live weight at slaughter
The LW of lambs at slaughter (de®ned either as degree of maturity or as proportion of mature weight) affected signi®cantly the cholesterol content of their carcasses. Given the range of PMW used in this study, results suggest that the high levels of cholesterol content in carcasses must have been deposited before lambs reach the ®rst half of their mature LW. In experiment 1, cholesterol content in carcass fat
decreased with advancing carcass maturity. For the two younger maturity groups, the cholesterol content was higher between the three breeds with the S lambs having consistently the highest levels in experiments 1 and 2. In experiment 3, the cholesterol content did not seem to be different between carcasses of lambs slaughtered at the two PMW. The lack of signi®cance due to PMW in experiment 3 may be attributed to the fact that there were no signi®cant differences in carcass traits when carcasses were compared at similar degree of maturity (Hopkins and Nicholson, 1999).
Based on PMW differences, as well as on differ-ences in fat content, one would thus expect that the mature carcasses would contain more cholesterol. However, this was not the case either in carcass samples from experiment 1 or from experiment 2 (Tables 3 and 4). It seems that the cholesterol content is not attributable to the differences in the amount of fat in the carcasses. Similarly, Hoelscher et al. (1988) suggested that cholesterol content does not depend directly to the ether-extractable fat content of the carcasses. Nevertheless, there was a general trend for cholesterol content to be lower in fat samples extracted from carcasses as TSLW increased.
5. Conclusion
The results suggest that there are possibilities of modifying body composition by manipulation of post-weaning nutrition, especially reducing the cholesterol content in carcass fat, in lambs slaughtered at a wide range of live weights. In such situation, however, as nutritional management and degree of maturity changes, breed remains the main factor determining the cholesterol content in carcass fat. Results also suggest that the provision of irrigated, sown pasture, could be used to produce consumer acceptable car-casses at much heavier weights than those which are traditionally preferred in Greece with a considerable lower cholesterol content.
Acknowledgements
Greece and Spain. The assistance, also, of the farmer Mr G. Zygoyiannis and his family is gratefully acknowledged.
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