Carcass characteristics and instrumental meat quality of suckling kids and lambs

Meat from very young, milk-fed, small ruminants is an appreciated product in Mediterranean countries where milk is the main product derived from the herds. Nevertheless, many aspects of the quality of the products are virtually unknown for many goat breeds, especially among those that are reared for their meat. In this study, the quality from 50 animals from 5 local goat breeds (one dairy purpose and 4 meat purpose) and 19 lambs (from Churra, a dairy breed) was compared at commercial cold carcass weights of 4.4-6.6 kg. Carcass quality, ultimate pH and meat colour were assessed following standard procedures. Statistical differences (p < 0.05) were found in all of the variables analysed. Some of these differences might have been due to the influence of the genotype, the dam’s production potential, or differences in carcass weight and age, but most were species dependent. Lambs differed from the kids, especially from those of meat purpose breeds, due to their high proportion of bone (25.0 vs. 21.3 to 23.7%), and a more intense meat colour (higher hue: 29.2 vs. 23.4 to 28.7, and chroma: 14.6 vs. 12.1 to 14.6). Among the goat breeds, Murciano Granadina (dairy breed) and Blanca Celtibérica (meat breed) were the most different in terms of carcass morphology, fatness, and meat colour. The other three local meat-purpose goat breeds (Moncaína, Negra Serrana, and Pirenaica) differed little. To obtain a better understanding of goat species, the differences among breeds, in kids or in their most common products, require further studies. Additional key words: carcass morphology; colour; goat; pH; sheep; tissue composition.

Product quality in suckling small ruminants produced (Ekiz et al., 2010).Given the need to increase the income of goat meat producers, objective information about the quality of the product (carcass and meat) is a necessary argument to get the consideration of a specific quality product for local, national, and supranational (i.e., European Union) authorities.The different species have a logical competence in the marketplace because there is a specific and maximum amount of meat per capita and per year consumed in developed countries.Despite the fact that the amount of goat meat consumed is small, it commands a below-average price compared to other meats such as mutton, which is attributed to the popular belief that goat meat is inferior to mutton, even though research suggests otherwise

Introduction
On a global scale, the production of meat from small ruminants is relatively small; however, in some regions, especially dry or mountainous habitats, where other species cannot thrive, small-ruminant species are very important.Goat products such as meat, milk and dairy products are important protein sources of animal origin for local people of rural areas, especially in developing countries (Ekiz et al., 2010).Also, they represent a growing market share in many developed countries (Haenlein, 2004).Thus, among sub-developing, developing, and developed countries, agricultural objectives differ, and subsistence, quantity, and quality often are their respective objectives.
In the lamb meat industry, many commercial branches, trademarks, and Geographical Protected Indications (GPI) exist, but generally this is not true in the goat meat industry, especially when we considered meat purpose breeds.Those breeds, which are not milked, are raised in agro-pastoral production systems on arid rangelands with traditional, socially tolerant, and sustainable techniques, and in harmony with the local environment (Shrestha & Fahmy, 2005).Goats are no longer synonymous with underdevelopment and poverty because they can be an important source of products in many parts of the world (Dubeuf & Boyazoglu, 2009).
Meat goats include the majority of breeds not specialised for either dairy or fibre production and their numbers are increasing (Shrestha & Fahmy, 2005).On one hand, the population of these breeds is small, and they are considered among the endangered breeds, which have a limited geographical distribution.On the other hand, in many countries, including Spain, France, and Italy, a significant proportion of the meat produced is sold in domestic markets, where it is seasonally much appreciated (Le Jaouen, 1997).Frequently, kids are sold as suckling animals, but without specific quality identification, a positive cue in many markets (Rubino et al., 1999;Schnettler et al., 2009).In general, kids are weaned at 2-3 months of age and goats are milked for the next 4-6 months.In this production models, kids are slaughtered immediately after weaning at 10-15 kg live weight and therefore low weight carcasses are Abbreviations used: BC (Blanca Celtibérica meat goat breed); BG (buttock perimeter); CCW (Cold Carcass Weight); Ch (Churra dairy ewe breed); EF (breastbone fat thickness); F (pelvic limb length); G (buttock width); GPI (); K (carcass external length); LD (Longissimus dorsi muscle); MG (Murciano Granadina dairy goat breed); Mo (Moncaína meat goat breed); NS (Negra Serrana meat goat breed); PCA (Principal Component Analysis); Pi (Pirenaica meat goat breed); Th (chest depth).
studied the importance of the breed in both carcass and meat quality.As it happens in lamb, breed is more important for carcass characteristics than for meat quality (Dhanda et al., 2003;Monte et al., 2007;Ekiz et al., 2010).Few studies, however, have compared them with each other, or with other species (Smith et al., 1974;Griffin et al., 1992;Schönfeldt et al., 1993;Rødbotten et al., 2004), and very few have assessed meat from very young, mainly milk-fed animals, particularly in goats (Banskalieva et al., 2000).
The aim of this study was to compare the carcass and instrumental meat quality, in milk-fed, very young animals, from different goat breeds, and from one labelled, GPI-EU, recognized lamb product.
All the animals were males reared in their respective local areas following local husbandry practices.All of them were unweaned and reared on their dam´s milk.Animals were selected, to be representative, for their respective Breeder Associations, at least from two different farms.

Slaughter and post-slaughter conditions
Animals were transported from farms in accordance with welfare specifications and slaughtered in local EU-licensed abattoirs in their respective areas of origin.
After 24 h of chilling under commercial protocols, carcasses were transported to the laboratory where carcass quality evaluations and sampling were performed at 48 h of ageing.
The left thoracic limb was sampled (Colomer et al., 1988) and dissected, to remove the muscle, subcutaneous, prescapular, intermuscular fat, bone (and cartilage), and others.Results were expressed as the proportion (%) of the dissected components.

Sampling and instrumental meat quality
After carcass evaluation, the Longissimus thoracis muscle was excised from the right carcass side and its ultimate pH was measured using a portable CRISON 507 pH meter equipped with a penetrating electrode in its cranial portion.After 15 min of blooming, meat colour (h* and C*) was evaluated using a portable Minolta colorimeter (CM-200), in the CIE L*a*b* space, with the standard illuminant D 65 and a 10° standard observer.Results were expressed as the average of three measurements of the same surface area (on the LD muscle between the lumbar and thoracic regions).

Statistical analyses
A General Linear Model (GLM) in SAS 8.02 assessed the effect of breed on carcass characteristics and meat quality.Breed had a highly significant (p ≤ 0.01) effect on cold carcass weight (p ≤ 0.001); therefore, with the exception of those associated with the tho-Product quality in suckling small ruminants racic limb composition, which were expressed as percentages, carcass quality variables were reanalysed using a GLM that included cold carcass weight as a covariate.When F-tests were significant at p ≤ 0.05, means were compared using Duncan's Test.All of the carcass and instrumental meat quality variables of all of the breeds were subjected to a Principal Component Analysis (PCA).

Carcass morphology and carcass conformation
All of the carcass morphology and conformation variables differed significantly (p ≤ 0.01) among breeds (Table 1).Average carcass weights ranged from 4.38 kg (MG breed) to 6.56 kg in BC breed.In goats, all linear carcass variables were greater (p ≤ 0.001) in the BC and NS breeds than in MG breed.Nevertheless, Ch showed the highest fatness score (without significant differences with BC breed) and the lowest breastbone 4 fat thickness (p ≤ 0.001), although without significant differences with MG and Mo breeds.When data were covariated by the carcass weight, smaller differences were appreciated (Table 2).Although BC remained with the longest pelvic limb (p ≤ 0.01), only significantly different with MG and Mo, NS showed the widest buttock (p ≤ 0.01), only significantly different with Ch and MG, and PI the deepest breast (p ≤ 0.001), only significantly different with Ch, MG and Mo.Lambs had, comparatively, an important development of the buttock perimeter (Table 2), which was associated in some extend, with their conformation score.

Carcass fat and colour measurements
Means and covariated mean values for fatness, breastbone fat thickness, and carcass colour score, are showed in Tables 1 and 2, respectively.Results for fatness of the goat breeds did not differ significantly, even considering the lower slaughter weight of MG.Ch lambs had higher (p ≤ 0.001) fatness scores, with the exception of BC and MG in uncovariate and covariate means, respectively, and lower (p ≤ 0.001) breastbone fat thickness (4 mm), with the exception of MG and Mo and MG, Mo and BC in uncovariate and covariate means respectively, than the goat breeds did.
Carcass colour scores, in uncovariate and covariate values, were especially low (p ≤ 0.001) in the MG animals, although there were not significant differences with the rest of the compared breeds, except BC, in covariate data (see Tables 1 and 2).Ch lambs and NS kids also showed low values, although they did not differ from the other studied goat breeds.

Shoulder composition
Breeds differed significantly in their shoulder tissue composition (Table 3).The lowest differences (p ≤ 0.05) were found in intermuscular fat and others percentages.The percentage of muscle was lower (p ≤ 0.001) in the Ch sheep and BC goats, without significant differences with MG and NS breeds.
BC goats had the highest percentages of the three fat depots.The proportions of fat and bone in the most muscular (higher muscle percentage) breed, Mo, were intermediate among the breeds evaluated in the current study, being the genotype a significant effect.The kids of the MG breed had the lowest subcutaneous fat (p ≤ 0.001), and the kids of the NS breed had the lowest intermuscular fat (p ≤0.05) percentages, although only these differences only were significant with BC goat breed.
Ch sheep had a relatively high subcutaneous fat content, but it had the lowest percentage of prescapular fat.Intermuscular fat of Ch lambs and of the goat breeds did not differ (p ≥ 0.05) significantly.

Instrumental meat quality
The colour variables and ultimate pH differed significantly (p ≤ 0.01) among species, being ultimate pH the lowest (p ≤ 0.001) in Ch sheep (Table 4), without significant differences (p ≥ 0.05) with Mo and Pi animals.The highest L* value (no statistically different from Ch values) and the lowest a* values (p ≤ 0.001) were found in the meat from MG kids, and the lowest L*, without differences (p ≥ 0.05) with Pi, and the highest a* (p ≤ 0.001) without differences (p ≥ 0.05) with Ch and Pi, were from BC breed.Meat yellowness (b*) did not differ significantly among goat breeds, but was significantly higher (p ≤ 0.001) in lamb meat.In addition, lamb had the second highest values of redness and lightness.
Ch and MG breeds had the highest (p ≤ 0.01) hue values, which were significantly higher (p ≤ 0.01) than those of the other goat breeds, which did not show differences among them.Chroma was higher (p ≤ 0.01) in the meat from Ch lambs and BC kids, but not significantly different from that of Pi kids.MG kids had the lowest (p ≤ 0.01) chroma.

Principal component analysis
The first two principal components explained 77.54% of the variability in the model (Fig. 1).PCA 1 (49.2% of the variability) was more associated with the colour score a*, and fat indicators in its positive scale, and PCA 2 (28.3% of the variability) was more associated with fatness scores and b* in its positive scale and ultimate pH in the negative one.

Carcass morphology and carcass conformation
BC and NS breeds, the two with the highest carcass weights, are those that have the highest adult weight in males, which indicates later maturity and the need for higher slaughter weights to reach appropriate levels of fatness.In addition, those breeds are reared for meat (in contrast to the dairy MG), and a high slaughter weight is needed to take full advantage of their productive performance, which is unlike milk breeds in which early weaning and slaughtering are used to increase the dam's milk commercialisation.Ekiz et al. (2010) also justify differences among breeds considering the differences in body size and production type.
Typically, carcass weights and carcass measurements are positively correlated (Marichal et al., 2003), and because of that, we covariated those variables by weight.In the current study, the uncovariate values of the linear carcass variables were higher, between goat breeds, in BC.This agrees with Peña et al. (2007) who observed an increase in carcass measurements and indexes due to differences in slaughter weight.But when the comparisons were made with covariate means, only chest depth maintained that differences.
The morphology of the Ch carcasses was similar to those previously reported in the same breed and commercial type (Sañudo et al., 1997), and typical of the Lechazo de Castilla y León PGI (Miguélez et al., 2006).In the current study, the Ch had intermediate values for weight and most linear carcass measure- ments (except those related to buttock perimeter).Typically, goats have longer limbs than sheep, and have poorer carcass morphology, even considering that Ch is a dairy sheep breed.This statement is especially evident when covariated results are compared (Table 2).
In this case, Ch breed had the highest buttock perimeter (p ≤ 0.001), which differed significantly from those of the other goat breeds.In the same way, when covariated means were examined, there were fewer differences between the meat and dairy goat breeds than expected, with MG having intermediate values, which reflected the amyotrophic condition of the species, although some exception could be indicated, such as Boer breed, which has an acceptable meat conformation (Shrestha & Fahmy, 2005).

Carcass fat and colour measurements
Fatness of the goat breeds was, in the current study, was similar.Also, Dhanda et al. (1999a) did not find significant differences in the fat thickness of kids from five genotypes that were slaughtered at CCW from 6.2 to 7.0 kg, having all of them had a fat thickness of only 1 mm.
On the other hand, sheep tends to deposit more subcutaneous fat than at the breast level, which might explain our results, although no significant differences existed with all the goat breeds, (higher fatness scores and lower breastbone fat thickness), because fatness score is based on the carcass surface.Thus, the breast is the site for the evaluation of body condition in goats, and in sheep the site is in the lumbar region (Delfa et al., 1998;Teixeira et al., 2011).
Our carcass colour scores were very low, as previously found by other authors (Martínez Cerezo et al., 2005), which reflected the milk diet of the young ani-mals since milk is not rich in iron.This was especially true for dairy specialised breeds, which have subsequently more milk nutrients disposability to young lambs and kids.Also, the relatively low values found in NS kids, although without significant differences, were probably due to that this breed has a high adult live weight, which might have led to a relatively low physiological maturity and, consequently, low iron content at the studied slaughter weights (Sañudo et al., 1998).

Shoulder composition
Shoulder tissue composition is a reasonable predictor of carcass tissue composition in kids (Argüello et al., 2001).In the former study, the bone content of the Ch carcasses (25.0%) was over 2% higher (p ≤ 0.001) than in any other breed analyzed in the current study, but less than the value (26.5% in the thoracic limb) reported by Miguélez et al. (2006) and higher than the value (24.7% in the in the half carcass) reported by Sañudo et al. (1997) for the same breed and commercial type.
Probably because BC breed had the heaviest carcasses, without significant differences with NS breed, it had the highest proportions of the three fat depots, although without significant differences with some breeds depending on the fat deposit considered, showing the importance of the weight -age relationship, in the development of this later development tissue (Zygoyiannis et al., 1990 for lambs;andDhanda et al., 2003, andAtti et al., 2004, for goats).In some cases, slaughter weight is the main factor influencing carcass composition (Mahgoub et al. [2005], in Jebel Akhdar goat breed slaughtered at 4.6, 7.9 and 13.6 kg of cold carcass weight or in Pérez et al. [2007], in suckling lambs slaughtered at 10 or 15 kg, live weight), although  Marichal et al. (2003) did not find a significant relationship between composition and slaughter weight, and Todaro et al. (2002) only found significant differences in the proportion of muscle in the pelvic limb.Also, the genotype could have a significant effect in carcass composition because of differences in maturity, and the disposability of milk because of its energetic value and the subsequent possibility of accumulating more fat.MG breed showed the lowest subcutaneous fat percentage, although only significantly different from BC breed, which reflected the tendency for dairy breeds to store more visceral fat than carcass adipose tissue (Dhanda et al., 1999a;Marichal et al., 2003), and the largest proportion of intermuscular fat.This deposit has been described as precocious, in relation to the total carcass fat (Delfa et al., 1994), and it might develop quicker because of the high nutritional level of MG kids, that result from their dam's dairy production potential.In this way, in Marichal et al. (2003) study about the Canary Caprine Group, dairy breed, only intermuscular fat deposits varied significantly among several slaughter weights.
Generally, goats have less fat content than do sheep, although the extent of the difference can vary depending on the type of the fat deposit considered (Schönfeldt et al., 1993;Sañudo et al., 1997).

Instrumental meat quality
The pH values found in the current study, in Ch breed, were similar to those found by Martínez Cerezo et al. (2005) in the same breed and commercial type.These results were lower, without significant differences with Moncaina and Pi breeds, than in the studied goat breeds.Possibly, kids are more sensitive than lambs to the stress of transport, handling, and lairage (Ripoll et al., 2011), particularly the MG kids, the youngest animals in the study, being more susceptible to emotional stress caused by noise, transport and social disruption (weaning) than older goats (Kannan et al., 2003).Also, González et al. (1983), Argüello et al. (1999), Marichal et al. (2003) and Ripoll et al. (2011) found that the smallest carcasses had the highest pH.
In the same way, differences in pH among breeds might also reflect differences in their responses to handling (Young et al., 1993;Monte et al., 2007).Nevertheless, differences in ultimate pH among the goat breeds other than MG were not (p ≤ 0.001) significant (range = 5.76-5.79),showing there is not effect of breed, in goats with similar purpose.In any case, with the exception of MG, our results were similar to those of Swan et al. (1998) in the Cashmere breed (5.70) and crossbreed (5.78), and lower that those of Boer goat (6.04), even in electrical stimulated carcasses (King et al., 2004).
Lightness in meat is associated with young animals, especially with milk fed lambs (Rubino et al., 1999), which are preferred in some areas, such as Mediterranean countries.Spanish consumers associate meat from suckling kid and lamb as being tender, juicy, tasty and, especially in the case of kid meat, with a high price (Sañudo et al., 1998).On the other hand, colour attributes might be the most important factor for distinguishing among species (Rødbotten et al., 2004).In the current study, the L*a*b* values in kids were lower than those found in the literature in heavier animals (King et al., 2004), especially L* and a* (Monte et al., 2007).Nevertheless, meat redness was higher than in Girgentana goat (Todaro et al., 2002), a breed that is known to have meat with particularly low a*.
MG kids showed the lowest a* and highest L* (without significant differences with Ch breed) values, probably because these animals were fed exclusively with milk, been weaned and slaughtered relatively early.Redness reflects the presence of myoglobin and the availability of iron (Sañudo et al., 1997;Martínez Cerezo et al., 2005;Suman et al., 2009), which is virtually nil in a milk diet.Also, although L* can be positively correlated with myofibrilar structure and negatively with pH (Marichal et al., 2003), it might have been more related to their evident paleness because of the limited amount of myoglobin (Dhanda et al., 1999b).The higher weight-age and, probably, the presence of some non-milk components in its diet and the subsequent increase in myoglobin might have contributed to the high redness and low lightness, without significant differences with Pi breed in both variables and with Ch lambs in redness, in the meat from BC kids (Martínez Cerezo et al., 2005).In kids, it has been demonstrated that differences in slaughter weight are not significant in muscle fibre type proportions and areas (Marichal et al., 2003), thus, its implication on meat colour could be of little importance.
Meat yellowness was higher in lamb meat, being similar to previous results found in the same breed by Sañudo et al. (1997), and in agreement with the colour consideration that a trained panel gave to the lamb colour when comparing with colour from goat and other species (Rødbotten et al., 2004).Also, lamb had, comparatively, higher values of a* and L*.In this case, L* might have been related to the low pH values of the lamb meat (Webb et al., 2005).Also Babiker et al. (1990) found higher L* and b* values in lamb than in goat, which had higher redness.The higher L* and b* values of the meat from Ch lambs might produce a more youthful aspect, as was suggested by King et al. (2004).Hue values did not show differences among goat breeds, except MG, coincidentally with Oman et al. (2000) in several Boer breed and crosses slaughtered at a similar age.
Chroma was, between goat breeds, higher in the meat from BC, without differences with Pi meat, the heaviest goat breed.It has also been suggested that a decrease in hue and an increase in chroma values are related with a carcass weight increase (Teixeira et al., 2011).The NS, Mo, and Pi goats did not differ significantly among them.Muscle colour is very important in kid meat and it should be pale pink.In the current study, chroma values were even lower than the values in kids slaughtered at a cold carcass weight of < 3 kg (Marichal et al., 2003).Thus, it could be expected a high meat visual acceptability in all the breeds, although some differences between our and Marichal et al. (2003) results might have been due to differences in methodology (i.e., the latter study did not specify blooming time).Nevertheless, chroma is influenced less by the chemical state (oxidative process) of the myoglobin than hue is (Renerre, 1982).

Principal component analysis
In the PCA, Ch lambs appeared in a different quadrant (upper left) than the other goat breeds, and was more associated with b*, the proportion of bone, h*, and L*.This result would show the differences in the carcass and instrumental meat quality (ultimate pH and colour) between lambs and kids.Also, Schönfeldt et al. (1993) observed significant differences between these two species, even using other measures of quality.
Among the goat breeds, BC, which had the heaviest carcasses, was clearly distinguished from the others because it was alone in the upper right quadrant, with positive tendencies on both axes.BC was associated with carcass weight and carcass measurements, conformation score, redness, and proportion of subcutaneous fat.All of the other goat breeds were in the negative area (two lower quadrants) of the PC2.MG was placed quite far from the central point, although in the same quadrant as Mo breed.Nevertheless, Mo breed was very close to ultimate pH and proportion of muscle, and closest to NS and Pi, which were in the same quadrant and associated with external fat thickness, proportions of prescapular and intermuscular fat, and colour score.
In conclusion, the lamb and goat products from very young and milk-fed animals differ in carcass characteristics and some instrumental measurements of quality.Even at a young age, there are some differences in quality among the goat breeds, which are to some extent more closely associated with age at slaughter and the milk capacity of dams, given that the kids of dairy breeds have lighter meat than those from meat purpose breeds.Nevertheless, some quality labels could be justified within goat species.To obtain a better understanding of the differences among goat breeds in the quality of their carcass and meat, more comparisons among local breeds are needed and different slaughtering criteria (i.e.age, weight, feeding system) should be considered to get a wide and real point of view of the breed influence in the quality of goats.

Table 3 .
Breed and species effects on shoulder composition (%) in suckling kids and lambs (means and SED) * Product quality in suckling small ruminants

Table 4 .
LD muscle ultimate pH and colour (15 min of blooming) in suckling kids and lambs (means and SED)