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Small Ruminant Research 78 (2008) 123–133

Available online at www.sciencedirect.com

Effects of feeding system on carcass and non-carcasscomposition of Churra Tensina light lambs

M. Joy ∗, G. Ripoll, R. Delfa 1

CITA-Centro de Investigación y Tecnología Agroalimentaria de Aragón, Avda. Montanana 930,50059 Zaragoza, Spain

Received 21 January 2008; received in revised form 26 May 2008; accepted 29 May 2008Available online 9 July 2008

bstract

Thirty-eight single male lambs (3.6 ± 0.08 kg live weight at birth) were used to study the influence of feeding system on carcass andon-carcass composition of Churra Tensina light lambs. Treatments: indoor (IND), lambs housed indoors consuming concentrated libitum until weaning at 53 days of age, and ewes grazing 8 h a day without their offspring and receiving a supplement ofarley meal after grazing; grazing (GR), ewes and lambs grazed continuously without concentrate and lambs were unweaned.hen lambs reached 22–24 kg live weight they were slaughtered. Carcass and non-carcass composition was recorded. GR lambs

isplayed higher carcass shrink (P < 0.05) and lower dressing percentage (P < 0.01) than concentrate-fed lambs. IND lambs hadore body fat mainly due to the heavier kidney (P < 0.001) and subcutaneous (P < 0.001) fat depots. Total non-carcass weight was

ot affected by treatment (P > 0.05), but red organ (heart, lung and trachea, thymus, liver, spleen, kidney, diaphragm, pancreas,all bladder, bladder, and testicles and penis), digestive tract (stomach, small intestine and large intestine) and head, skin, andeet (HSF) weights differed between treatments (P < 0.05). IND lambs had heavier red organs and HSF (P < 0.05) although thisifference disappeared when expressed as a percentage of empty body weight. Small intestine weight in grazing lambs was heavierP < 0.001) and, consequently, the total digestive tract differed similarly (P < 0.01). Treatment influenced the weights (P < 0.05) ofll joints except leg (P > 0.05), showing heavier joints for IND carcasses. The feeding system had a greater effect on subcutaneousat (P < 0.001) than on intermuscular fat (P < 0.05) in most of the standardized joints. IND carcasses produced a greater proportionf muscle/bone in all joints, except neck, whereas GR produced a greater proportion of muscle/total fat due to the lower amountf fat recorded in this treatment. The percentage of fatty acids was not affected by treatment (P > 0.05) although the percentage of18:3 was greater and the ratio of C18:2/C18:3 was lower in grazing-fed lambs. The absence of any effect of treatment on the fatty

cid percentages may be influenced by the short raising period and by the similar amount of intramuscular fat in both treatments. It isoncluded that light lambs reared under grazing conditions can produce carcasses of acceptable quality, due to the lower percentagef subcutaneous fat, but with a similar intramuscular fat content.

2008 Elsevier B.V. All rights reserved.

eywords: Churra Tensina lambs; Carcass composition; Feeding system; Dig

∗ Corresponding author. Tel.: +34 976 716 442;ax: +34 976 716 335.

E-mail address: mjoy@aragon.es (M. Joy).1 In memoriam.

921-4488/$ – see front matter © 2008 Elsevier B.V. All rights reserved.doi:10.1016/j.smallrumres.2008.05.011

estive tract; Red organs

1. Introduction

The Churra Tensina sheep is an endangered, localcoarse wooled hardy breed (around 4000 head) belong-ing to Churra group, which is raised for lamb productionin the mountain area of southern Pyrenees. Lambs of

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124 M. Joy et al. / Small Rumin

this breed can be raised with dams until slaughter onpermanent mountain pastures during spring, with slightpenalties on their performance when compared with theirconcentrate-fed counterparts (Joy et al., 2004; Álvarez-Rodríguez et al., 2007). In a previous report, it has beenobserved that the carcass conformation score and fatnessdegree were lower in pasture-fed than in concentrate-fed lambs, according to the subjective classificationscale of the EU, but barely undetectable differenceswere found in meat and fat colour when assessed sub-jectively and using a spectrophotometer (Joy et al.,2008).

However, little knowledge is available regardingobjective carcass and non-carcass characteristics inextensive production systems of light lambs in com-parison with the indoor production system, which isthe traditional management system in Spain. Lambs arefed on a concentrate-based diet plus milk until weaning(45–50 days old) and thereafter are fed only concentrateuntil slaughter at light live weights (18–24 kg), normallyearlier than 90 days (the ‘Ternasco’ commercial cate-gory).

The carcass quality of lambs reared on pasture isregarded as being superior by consumers and couldbe physically, biologically and economically sustain-able (Zervas et al., 1999). The increasing demand forhealthy, safe meat products (Corcoran et al., 2001) isstimulating market interest in extensive systems (Gilet al., 2000). Forage-based sheep production systemsare more economical in comparison to indoors systems(Woodward and Fernández, 1999). It follows that graz-ing is an important part of a sustainable productionsystem that keeps local sheep breeds such as ChurraTensina.

Depending on the cultural context, the non-carcasscomponents (offals) may be considered as waste materialthat is thrown away, or as delicacies that have com-manded a high price in the past couple of years. In fact,in most of countries the favourite dishes chosen by chefsto cook and to eat are offals (Consensus, 2007). Non-carcass components are an important part of the sheepfarmers’ economies. One of the few studies conductedon offals concluded that their commercial value repre-sented 16.4% of the value of live animals and 15.9% ofthe carcass value (Delfa et al., 1999).

The carcass and non-carcass composition of ChurraTensina lambs are not well known. The purpose of thisstudy was to assess the effect of feeding management

(grazing- or concentrate-fed) on the carcass composi-tion, wholesale cut, tissue percentages, intramuscularfatty acids, and the non-carcass components of ChurraTensina light lambs.

search 78 (2008) 123–133

2. Materials and methods

2.1. Animal management and experimental design

Thirty-eight single male lambs (3.6 ± 0.08 kg live weightat birth) were selected from the experimental flock of “La Gar-cipollera” Research Station (945 m a.s.l., north-eastern Spain).After birth, lambs remained indoors with their dams for somedays to ensure maternal bonding. Ewes and lambs were thenrandomly allocated to two adjacent paddocks (n = 19). Lamb-ing date, parity, body condition score and live weight of ewesand lambs were taken into account to balance groups. Thetreatments were

1. Indoor (IND): lambs were housed indoors (10 × 10 m2)and ewes grazed eight hours a day (0800–1600 h) withouttheir offspring and received a supplement of barley meal(119 g/kg CP, 248 g/kg NDF on DM basis) after grazing.Lambs were fed concentrate ad libitum (182 and 167 g/kgCP, 190 and 212 g/kg NDF, on DM basis, the first monthand subsequently). Lambs were weaned at 50–55 days ofage (52.8 ± 0.86 days). Both ewes and lambs were givenbarley straw ad libitum (37 g/kg CP and 807 g/kg NDF, onDM basis).

2. Grazing (GR): lambs and dams were continuously stockedon a permanent pasture. No concentrate was available todams or lambs. Lambs suckled their mothers and grazeduntil slaughter.

The pasture was composed of 22% legumes (mainly Tri-folium repens), 68% grass (the main species were Festucaarundinacea, Festuca pratensis and Dactylis glomerata) and10% other species (mainly Rumex acetosa and Ranuncu-lus bulbosus). The stocking rate was 32 ewes per hectare(0.57 ha/treatment). For further details of daily intake, see Joyet al. (2008).

All the animals were supplied with a mineral vitamin sup-plement ad libitum. Procedures were conducted according tothe guidelines of the Council Directive 86/609/EEC (EuropeanCommunities, 1986) on the protection of animals used forexperimental and other scientific purposes.

2.2. Slaughter procedure

When lambs reached 22–24 kg of live weight they weretransported to the experimental abattoir at the Research Insti-tute in Zaragoza, which is located 180 km from the farm. Theywere weighed on arrival and accommodated, until their slaugh-ter, according to their original treatment. No fasting period wascarried out. GR lambs received green forage and those fromIND treatment received the same concentrate as that offeredduring the experimental period. Twenty hours after their arrival,

lambs were slaughtered according to EU regulations.

The contents of the gastro-intestinal tract were weighed tocalculate the empty body weight (EBW). Internal fat depots(pericardial, omental, mesenteric, pelvic and kidney), offalcomponents and hot carcasses (HCW) were weighed. Offal

M. Joy et al. / Small Ruminant Research 78 (2008) 123–133 125

F , BreastV

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ig. 1. Joints of the lamb half carcass. I, Shoulder (Thoracic 3 limb); IIII, Tail. Figure adapted from Colomer-Rocher et al. (1988).

omponents were grouped into head, skin and feet (HSF), redrgans (heart, lung and trachea, thymus, liver, spleen, kidney,iaphragm, pancreas, gall bladder, bladder, testicles and penis),nd digestive tract (stomach, small intestine and large intes-ine). Total non-carcass components were calculated groupinged organs, digestive tract, HSF and fat depots, excluding intra-uscular fat.

.3. Wholesale cuts and dissection

After 24 h of refrigeration the cold carcass weight (CCW)as recorded. The tail was removed and the carcass was care-

ully split longitudinally and the two halves were weighed.idney and pelvic fat depots were weighed and the percent-

ge of kidney knob and channel fat (KKCF) was calculated.he left side was cut into six standardized commercial joints

leg, rib, loin, shoulder, neck and breast) (Fig. 1) accordingo Colomer-Rocher et al. (1988). Each joint was weighed andissected into muscle, bone, subcutaneous fat, intermuscularat and waste (major blood vessels, ligaments, tendons andhick connective tissue sheets associated with some muscle)Colomer-Rocher et al., 1988). Total body fat was the sum ofericardial, omental, mesenteric, kidney, pelvic, subcutaneous,ntermuscular and tail fat.

.4. Meat chemical composition

Samples of M. longissimus thoracis from sixth to eighthertebrae were minced to determine the percentage of cruderotein (Dumas procedure; AOAC, 1999) and intramuscularat (AOCS, 2004). Next the portion of M. longissimus thoracist the 10th vertebrae was also minced for fatty acid analysis

FA). Fatty acid methyl esters were obtained using a solutionf boron trifluoride 20% in methanol (Rule, 1997). Analysis ofatty acid methyl esters was performed by gas chromatographyith a 30-m capillary column SP2330 (Supelco, Tres Cantos,adrid) and a flame ionisation detector with helium as the car-

; III, Leg (Pelvic limb); IV, Neck; V, Loin (Best part of neck); VI,Ribs;

rier gas at 1 mL/min. The oven temperature was programmedto increase from 150 to 225 ◦C at 7 ◦C per min. Injector anddetector temperatures were both 250 ◦C. Fatty acid content wasexpressed as a proportion of total amount of the fatty acidsidentified. The sum of saturated fatty acids (SFA), monoun-saturated fatty acids (MUFA), and polyunsaturated fatty acids(PUFA), as well as the PUFA/SFA and C18:2/C18:3 ratios, werecalculated.

2.5. Statistical analysis

Statistical analysis was performed by analysis of varianceusing the GLM procedure of SAS (1999). Effects of feedingsystem as fixed effect on all carcass and non-carcass compo-nents as well as their percentages were analysed according tothe following model:

Yij = μ + Di + ξij

where Yij is the dependent variable; μ the overall mean; Di theeffect of i feeding management (GR or IN); ξij is the residualerror.

Differences with a level of significance below 0.05 wereconsidered significant.

3. Results and discussion

3.1. Empty body weight, carcass characteristicsand dressing percentage

Lamb performance and carcass characteristics ofChurra Tensina lambs reared under grazing (GR) orconcentrate-fed (IND) systems are shown in Table 1.

As expected, IND lambs presented a higher growth rateafter 53 days of age than their GR counterparts dueto concentrate intake, which agrees with the results ofÁlvarez-Rodríguez et al. (2007) with the same breed.

126 M. Joy et al. / Small Ruminant Research 78 (2008) 123–133

Table 1Lamb performance and carcass characteristics of Churra Tensina lambs reared under grazing-fed (GR) or concentrate-fed (IND) systems

Item GR IND SE Significance

Weight at farm (kg) 23.0 23.3 0.22 n.s.a

Slaughter age 85.5 74.2 2.60 **ADG 53 days oldb slaughter (g/day) 217 292 15.6 **ADG from birth to slaughter (g/day) 242 281 8.0 **Transport losses (%) 2.6 1.9 0.33 n.s.Waiting losses (%) 1.6 0.7 0.65 n.s.Transport + waiting losses (%) 4.2 2.6 0.58 n.s.Empty body weight (kg) 18.8 19.6 0.23 *Hot carcass weight (kg) 10.4 11.1 0.17 **Carcass shrink (%)c 3.7 3.1 0.17 *Dressing percentaged 55.4 56.6 0.37 **

a n.s. = nonsignificant; *P < 0.05; **P < 0.01.

100/hoht.

b Age at weaning of IND lambs.c Carcass shrink (%) = (hot carcass weight − cold carcass weight) ×d Dressing percentage = hot carcass weight × 100/empty body weig

Losses due to transport and waiting time at the slaugh-terhouse were similar between treatments (P > 0.05).However, the feeding system had a significant effecton empty body weight (P < 0.01; Table 1), which waslower in GR lambs, and on carcass shrink, which washigher in the latter treatment (P < 0.05). Consequently,dressing percentage was lower in GR than in IND lambs(P < 0.01). Forage finishing systems increase digestivetract size and decrease external fat cover, resulting inlower dressing percentage (Fluharty et al., 1999; Bortonet al., 2005a). Priolo et al. (2002) observed similar resultsin lambs reared under grazing and indoor-fed systemsand slaughtered at 35 kg. In contrast, Caparra et al.

(2005) did not find any effect of feeding system on emptybody weight or dressing percentage in Merinizzata lightlambs reared on pasture or hay plus concentrate andslaughtered at 100 days of age. However, in contrast to

Table 2Total fat content (g) and percentage of fat depots (%) of Churra Tensinalambs reared under grazing-fed (GR) or concentrate-fed (IND) systems

Item GR IND SE Significance

Total fat content (g) 2251 2794 93.24 ***a

Pericardial (%)b 1.21 1.06 0.119 n.s.Omental (%) 11.2 10.0 0.570 n.s.Mesenteric (%) 10.30 8.01 0.351 ***KKCFc (%) 7.70 8.13 0.250 n.s.Kidney (%) 4.92 5.82 0.221 **Pelvic (%) 2.78 2.31 0.117 **Subcutaneous (%) 20.2 25.3 0.644 ***Intermuscular (%) 44.0 42.6 0.886 n.s.Tail (%) 1.30 1.42 0.104 n.s.

a n.s. = nonsignificant; *P < 0.05; **P < 0.01; ***P < 0.001.b Percentages are relative to total fat.c Kidney fat + pelvic fat.

t carcass weight.

the present study, Caparra et al. (2005) controlled con-centrate supplementation in stall-fed lambs in order toachieve similar average daily gain between treatments.

Significant effects of the feeding system on dressingpercentage and carcass shrinks when comparing lambsraised on pasture to drylot have been observed in otherstudies (Santos-Silva et al., 2002a; Caneque et al., 2003).The magnitude of the effect can be modulated throughmanagement practices such as concentrate creep feedingoutdoors (Santos-Silva et al., 2002a) and longer lactationperiods (Caneque et al., 2001; Sanz et al., 2005), whichin both cases enhance carcass fatness degree.

3.2. Internal fat depots and non-carcasscomponents

Feeding system had an effect on total body fat depots(P < 0.001; Table 2), mainly due to greater percentagesof kidney (P < 0.01) and subcutaneous (P < 0.001) fatdepots in IND lambs, whereas their GR counterpartshad greater percentages of mesenteric (P < 0.001) andpelvic fat (P < 0.01; Table 2). These results can be relatedto a pattern of development for carcass fat depots inthe following order: mesenteric, intermuscular, omental,pelvic and renal, subcutaneous, and finally intramuscu-lar (Teixeira et al., 1989). The greater average daily gainobserved from weaning to slaughtering (217 g/day vs.292 g/day in GR vs. IND, respectively) and the fatnessdegree recorded in IND lambs (Joy et al., 2008) couldexplain the differences in fat depot proportions observed

in the present study. Moreover, IND lambs were fed adiet higher in digestible energy than GR lambs encour-aging the production of ruminal propionic acid, which isa fat precursor (Vernon, 1981).

M. Joy et al. / Small Ruminant Research 78 (2008) 123–133 127

Table 3Main organs of non-carcass components of Churra Tensina lambs reared under grazing-fed (GR) or concentrate-fed (IND) systems

Organ mass GR IND SE Significance

Total non-carcass (g) 7097 7240 75.10 n.s.a

Total non-carcass/EBWb (%) 37.8 36.9 0.314 n.s.Internal fat depotsc (g) 499 517 19.09 n.s.Internal fat depots/EBW (%) 2.65 2.64 0.095 n.s.

Red organsHeart (g) 115 108 2.19 *Heart/EBW (%) 0.61 0.55 0.012 ***Liver (g) 411 457 8.04 ***Liver/EBW (%) 2.19 2.59 0.044 ***Kidney (g) 89 86 1.79 n.s.Kidney/EBW (%) 0.47 0.44 0.009 **Lungs and trachea (g) 446 456 16.21 n.s.Lungs and trachea/EBW (%) 2.37 2.32 0.074 n.s.Red offals (g) 1319 1413 26.00 *Red offals/EBW (%) 7.02 7.21 0.111 n.s.

Digestive tractForestomachs (g) 531 553 13.58 n.s.Forestomachs/EBW (%) 2.83 2.82 0.074 n.s.Small intestine (g) 793 652 21.82 ***Small intestine/EBW (%) 4.23 3.32 0.112 ***Large intestine (g) 287 285 10.78 n.s.Large intestine/EBW (%) 1.54 1.46 0.067 n.s.White offals (g) 1612 1491 30.59 **White offals/EBW (%) 8.61 7.60 0.171 ***

HSFd

Head (g) 1001 974 13.87 n.s.Head/EBW (%) 5.34 4.96 0.054 ***Feet (sum of four) (g) 576 582 9.08 n.s.Feet/EBW (%) 3.06 2.79 0.031 *Skin (g) 2089 2263 40.50 **Skin/EBW (%) 11.1 11.6 0.218 n.s.HSF (g) 3667 3819 46.98 *HSF/EBW (%) 19.5 19.5 0.22 n.s.

a n.s. = nonsignificant; *P < 0.05; **P < 0.01; ***P < 0.001.b

cbt(Efsnbwtew

Empty body weight.c Mesenteric and omental fat.d Head, skin and feet.

There were neither differences in total non-carcassomponents (Table 3) nor their relationship with emptyody weight (offal/EBW). Feeding system influencedhe weight of red organs, digestive tract and HSFP < 0.05; Table 3), but the proportions in relation toBW were similar between treatments (P > 0.05) except

or the digestive tract (P < 0.001). Breed, age, sex andlaughter weight are the main factors that influence theon-carcass weight (Delfa, 1992). In the present study,reed, sex, and slaughter weight were fixed factors,

hereas age at slaughter was determined by feeding sys-

em (P < 0.01) that affected non-carcass weight. Penat al. (2005), studying the effect of sex and carcasseight (19 and 25 kg of BW) of Segurena light lambs

on carcass and non-carcass characteristics, observedan average percentage of offal of 35.3% of EBW inmale lambs, concluding that this percentage decreasedas carcass weight increased, and females had a lowerpercentage than males. Delfa et al. (1999) comparedstall-fed of two breeds (Roya Bilbilitana and Ojine-gra de Teruel) slaughtered at similar body weight andreported that Roya bilbilitana lambs showed greaternon-carcass weight than Ojinegra lambs. The weight ofnon-carcass components, as well as its relationship with

EBW were similar in the present study to findings forthe Roya Bilbilitana breed but heavier than for Ojine-gra (Delfa et al., 1999) and Segurena lambs (Pena et al.,2005).

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128 M. Joy et al. / Small Rumin

The main offal components classified as red organs,the digestive tract and HSF, are presented in Table 3. Inrelation to red organs, concentrate-fed lambs had lighterheart (P < 0.05) and heavier liver (P < 0.001) weights,whereas kidney and lung weights were not affected byfeeding system (P > 0.05). When weights were expressedrelative to EBW, treatment had effects on the heart,liver, and kidneys (P < 0.01; Table 3); GR lambs hadgreater values for the heart and kidneys (P < 0.001) and alower value for the liver (P < 0.01). Fluharty et al. (1999)concluded that diet can influence visceral organ massand reported that lambs grazing alfalfa had a greaterliver weight than lambs concentrate-fed. However, inthe present trial, GR lambs exhibited a higher incidenceof parasithosis, mainly gastro-intestinal nematodes andcysticerci (Gómez-Rincón et al., 2006), than observedin IND lambs (data not showed), which may be partiallyresponsible for the present results. Moreover, the lowerliver weight would be in accordance with a decreasingplane of nutrition eliciting a reduced metabolic rate andmass of metabolically active tissue, such as the liver(Wester et al., 1995; Fluharty and McClure, 1997).

As for the digestive tract, GR lambs had a heaviersmall intestine (P < 0.001), whereas weights of the stom-ach and large intestine were similar between treatments(P > 0.05). Our results agree with Fluharty et al. (1999)who reported that lambs grazing alfalfa had a greatersmall intestine weight but similar reticulo-rumen weightto concentrate-fed lambs. The aforementioned authorsprovided a possible explanation for these unexpectedresults, suggesting that the amount of digesta reachingthe small intestine in lambs fed high-concentrate diets isnot sufficient to maintain tissue mass, whereas forage-based diets with large amounts of digesta entering thesmall intestine give rise to net tissue growth. Wester et al.(1995), studying planes of protein and energy nutritionin visceral organs in lambs, concluded that the digestivetract was more affected by physical characteristics of thediet than by level of nutrient intake.

Percentages of head and feet relative to EBW werelower for the IND treatment (P < 0.05). Atti et al.(2003) and Mahouachi and Atti (2005) reported that theweight of offal components rich in bone and/or with lowmetabolic activity (head, feet, lungs) varied slightly withdiet, given that these components are early maturingand less affected by dietary effects in growing com-pared with mature animals. Skin from GR lambs waslighter than those from IND (P < 0.01). However, when

it was related to EBW, there were no differences betweentreatments (P > 0.05). Skin has been considered a latematuring organ (Atti et al., 2003 and Mahouachi andAtti, 2005) and a decrease in fleece weight caused by

search 78 (2008) 123–133

a small decrease in fibre diameter has been associatedwith management practices restricting grazing (Adamsand Cronjé, 2003). Thus, this body component wouldbe less mature or more nutrient-restricted in GR than inIND lambs.

3.3. Wholesale cuts and dissection

Weights of standardized joints from left half car-casses are shown in Table 4. Leg, shoulder, and ribs werethe most important joints in both treatments, whereasneck and loin were of lesser importance, in agreementwith Pena et al. (2005). Feeding system had an effect(P < 0.05) on all joints except leg (P > 0.05) and the INDcarcasses had heavier joints as a result of their greaterhot carcass weight (P < 0.01). When leg and shoulderweights were related to CCW, the proportion of leg wasgreater for the GR treatment, whereas there were nodifferences observed in shoulder weight. In accordancewith this Borton et al. (2005b), when studying effectson carcass components of concentrate- or grazing-fedlambs slaughtered at heavy weights, reported that whole-sale cuts related with motor functions, such as legs, hada greater proportion of carcass in forage-fed lambs dueto a greater muscular development.

Treatment had an effect on total and subcutaneousfat of legs, ribs, shoulder and breast (P < 0.01), and onintermuscular fat of leg, ribs and breast (P < 0.05). Like-wise, concentrate-fed lambs had greater intermuscularand subcutaneous fat depots, in accordance with findingsof Díaz et al. (2002) and McClure et al. (2000). Someof the effects of the feeding system on carcass composi-tion were probably due to the effects of growth rate onthe partitioning of energy for tissue gain (Borton et al.,2005a,b). Tissue maturation follows the order of bone,lean and fat (Rouse et al., 1970). Besides, exercise ingrazing lambs can lead to mobilization of reserve lipidsto develop muscle tissue at the expense of subcutaneousfat (Díaz et al., 2002). Daily energy intake for GR lambsmay have been sufficient to meet energy requirementsfor bone and lean tissue but provided less energy forfat accretion (Murphy et al., 1994). Feeding system hadless effect on intermuscular fat (P < 0.05 in legs, ribs andbreast) than on subcutaneous fat (P < 0.001 in leg, ribs,shoulder and breast) in most of the standardized joints,as a consequence of the earlier maturation rate of theformer fat depots.

The ratio of muscle/bone was significant and greater

for IND carcasses in ribs (P < 0.01), loin (P < 0.05),shoulder (P < 0.01) and breast (P < 0.05). Carcassesfrom the GR treatment had a greater ratio of mus-cle/total fat than IND carcasses, being significantly

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129

Table 4Weight (g) and ratios of main tissues obtained by dissection of standardized joints from left half-carcass obtained from Churra-Tensina lambs reared under grazing-fed (GR) or concentrate-fed(IND) systems

Leg Ribs Loin Shoulder Neck Breast

GR IND SE GR IND SE GR IND SE GR IND SE GR IND SE GR IND SE

Total weight (g) 1607 1682 28.3 890b 1023a 20.3 370a 340b 7.7 976b 1038a 17.6 344b 371a 9.1 504b 566a 11.1TW/CCWa 34.3a 33.5b 0.19 18.9b 20.4a 0.20 7.9a 6.8b 0.15 20.8 20.7 0.16 7.3 7.4 0.15 10.7b 11.3a 0.14Muscle (g) 1042 1061 19.7 507b 542a 11.2 220a 204b 5.9 626 651 13.1 195 212 6.1 233b 258a 6.9Bone (g) 360 361 5.5 158 146 4.6 93a 75b 3.3 219 216 3.3 89 89 4.5 103 101 2.4Total fat (g) 204b 260a 11.5 225 335a 14.8 58 61 3.2 132b 171a 8.1 60 69 3.8 168b 207a 7.1Subcutaneous fat (g) 77b 112a 5.6 79b 130a 6.9 37b 59a 3.5 11 10 1.2 37b 55a 3.4Intermuscular fat (g) 95b 117a 6.4 88b 119a 8.2 58 61 3.2 95 112 6.5 49 60 3.6 131b 153a 5.9Pelvic fat (g) 33 31 1.9Kidney fat (g) 59b 86a 3.9M:Bb 2.9 2.9 0.04 3.3b 3.8a 0.11 2.4b 2.8a 0.10 2.9b 3.0a 0.04 2.5 2.2 0.20 2.3b 2.6a 0.08M:Fc 5.3a 4.3b 0.25 2.5a 1.7b 0.14 4.0 3.6 0.27 5.1a 4.0b 0.29 3.5 3.3 0.25 1.4 1.3 0.06Fat depot ratiod 0.8b 1.0a 0.06 1.0 1.2 0.10 0.4b 0.6a 0.05 0.2 0.2 0.03 0.3 0.4 0.03

Different superscripts mean significant differences (P < 0.05).a Total weight of the joint/cold carcass weight (g/kg).b Fat depot ratio = Muscle weight/bone weight.c Muscle weight/(subcutaneous + intermuscular + pelvic + renal fats).d Subcutaneous fat/intermuscular fat.

130 M. Joy et al. / Small Ruminant Research 78 (2008) 123–133

Table 5Chemical composition and fatty acid profile of M. longissimus thoracis of Churra-Tensina lambs reared under grazing-fed (GR) or concentrate-fed(IND) systems

Item GR IND SE Significance

Chemical componenta

Crude protein (%) 19.1 19.7 0.264 n.s.b

Intramuscular fat (%) 1.69 1.70 0.082 n.s.

Composition of fatty acids (as percentage of total fatty acids)C12:0 1.63 1.51 0.095 n.s.C14:0 4.87 4.71 0.235 n.s.C16:0 22.3 22.2 0.279 n.s.C16:1 1.80 1.89 0.048 n.s.C17:0 0.94 0.90 0.014 n.s.C17:1 0.67 0.66 0.012 n.s.C18:0 13.3 12.8 0.360 n.s.C18:1 37.7 38.4 0.523 n.s.C18:2 7.18 8.16 0.475 n.s.C18:3 1.95 1.72 0.179 n.s.C20:1 0.33 0.38 0.039 n.s.

SFA 43.3 42.4 0.459 n.s.MUFA 40.3 41.1 0.512 n.s.PUFA 9.14 9.87 0.400 n.s.PUFA/SFA 0.21 0.23 0.010 n.s.C18:2/C18:3 5.04 6.08 0.855 n.s.

a Wet basis.b n.s. = nonsignificant.

different in leg (P < 0.01), ribs (P < 0.001) and shoulder(P < 0.01). The lower amount of fat in GR carcasses wasresponsible for this greater proportion. The relationshipbetween subcutaneous and intermuscular fat was similaracross treatments, although leg (P < 0.05) and shoulder(P < 0.001) had greater values for IND lambs. In bothtreatments, the relationship between the two depots of fatalso showed that intermuscular fat was greater than sub-cutaneous except for ribs of the IND treatment (Table 5).Intermuscular fat was twofold, threefold and fivefoldgreater than subcutaneous fat of the shoulder, breast andneck, respectively; while on legs and rib the ratio subcu-taneous to intramuscular fat was closer to 1. In GR lambs,milk from dams and high pasture availability (Joy et al.,2008) were not enough to reach energy intake similar toconcentrate-fed lambs (IND), impairing fat biosynthesisand affecting to a greater extent subcutaneous fat due toits later maturation rate.

3.4. Chemical composition and fatty acids of meat

Neither crude protein nor intramuscular fat percent-

ages of meat were affected by treatment (P > 0.05;Table 5) in accordance with comparisons by Díaz et al.(2002) and Foti et al. (2005) of grazing- and concentrate-fed lambs. Murphy et al. (1994) studied the effect of

feeding management (alfalfa grazing, stall-fed, and graz-ing with finishing period) on carcass composition andtissue accretion rate of heavy lambs. Results showed thatcarcass protein was not affected and intramuscular fatwas the fat depot that was least affected by treatment.

The intramuscular FA percentage is affected by diet(Díaz et al., 2002), breed (Wood et al., 1999), age andweight (Rhee, 2000), and fatness degree (Nürnberg et al.,1998). The absence of any effect of treatment on intra-muscular fat content and on its fatty acid percentageswas unexpected. Bas and Morand-Fehr (2000) and Valvoet al. (2005) found differences in fatty acids of lambs38 days of age lambs exclusively fed milk of grazingand non-grazing ewes, which could be due to the differ-ences in milk FA percentages. Joy et al. (2008) comparedeffects of grazing vs. concentrate-fed lambs on milk FApercentages and detected differences only during the firstmonth of lactation. The present unexpected result maybe influenced by the short raising period and to the minoreffect of diet on intramuscular FA in ruminants.

The GR treatment increased, although not signifi-cantly, the percentage of stearic (C18:0) and linolenic

(C18:3) acids by 4 and 13%, respectively, in agreementwith findings of Díaz et al. (2002) and Santos-Silva etal. (2002b). Conversely, linoleic acid (C18:2) was 14%greater in IND than in GR lambs (P > 0.05). The great

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ercentage of linoleic acid of concentrates may havenhanced the percentage of this fatty acid (Sanudo etl., 2000; Valvo et al., 2005).

Percentages of SFA and PUFA are important dueo their influence on the healthiness of meat. While

ost of SFA are presumed to increase the risk of heartisease, PUFA and MUFA are generally regarded aseneficial for human health (Scollan et al., 2005). Dietsith a lower PUFA/SFA ratio of 0.45 are less healthy in

elation to cardiovascular disease. Conversely, the rec-mmended PUFA n − 6/n − 3 ratio is lower than 4.0British Department of Health, 1994). Ruminant fat isharacterized by a less healthy PUFA/SFA ratio butetter ratio of n − 6/n − 3 PUFA in relation to non-uminant fat (Enser et al., 1998). Feeding forage to sheepncourages proportions of n − 6/n − 3 PUFA vieweds healthier than for concentrated-fed lambs (Bas andorand-Fehr, 2000; French et al., 2000; Enser et al.,

998). In relation to this, Wood et al. (1999) found thatrass diets increase the deposition of n − 3 PUFA, but theroduction of SFA is also increased and the PUFA/SFAatio becomes less healthy.

SFA, MUFA and PUFA percentages were similaretween treatments (P > 0.05) in accordance with find-ngs of Díaz et al. (2002) and Velasco et al. (2001).owever, Caneque et al. (2003) observed a great effect of

he management system on SFA and MUFA percentages.reed, slaughter weight and feeding system could be

esponsible for these different results. Díaz et al. (2005)tudied fatty acids percentages in lamb meat from sev-ral countries and production systems, concluded thathe combined effects of diet, age, sex and breed produceifferentiation in meat fatty acid profiles. Although treat-ent did not influence the ratio C18:2/C18:3 (P > 0.05),R lambs had a 21% lower ratio, which suggest that thiseat was more healthy than that of IND lambs (Enser et

l., 1998).

. Conclusions

It is concluded that feeding management, grazing vs.rylot, affected body fat depots, which decreased withrazing treatment. Feeding system had a greater effect onubcutaneous fat than on intermuscular fat. Indoor treat-ent carcasses presented a greater muscle/bone ratio,hile GR had a greater muscle/total fat ratio given the

ower amount of fat recorded. GR lambs had greaterigestive tract mass than IND lambs, and minor dif-

erences were found in mass of red organs. Fatty acidercentages were unaffected by the feeding system. Thebsence of any effect of treatment on fatty acid percent-ge may be due to the short raising period and to the

earch 78 (2008) 123–133 131

similar percentage of intramuscular fat for both treat-ments. Light lambs reared under grazing conditions canproduce a carcass of a superior quality, in accordancewith the demands of consumers, due to the lower pro-portion of subcutaneous fat, but with a similar proportionof intramuscular fat in relation to drylot lambs.

Acknowledgements

The authors wish to thank S. Tort and G. Bleriot fortheir assistance in sample collection, M. Oloriz, M. Uri-arte and P. Rojo for their assistance in carcass dissection,and G. Estopanan for his technical assistance. Thanks toP. Albertí and J. Álvarez-Rodríguez for their helpful sug-gestions. Special thanks to the staff of La GarcipolleraResearch Station and of the CITA de Aragón. This studywas supported by the Ministry of Education and Scienceof Spain and the European Union Regional Developmentfunds (INIA RTA-03-031).

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