Researches concerning the improvement of carcasses issued from reformed and fattened adult sheep

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1 Animal Husbandry REVIEW ARTICLE Researches concerning the improvement of carcasses issued from reformed and fattened adult sheep Constantin Pascal, Ioan Gîlcă, Gherasim Nacu Faculty of Animal Science, University of Agricultural Sciences and Veterinary Medicine Iasi, Romania Abstract Approximately 1015% from the adult sheep in each flock is reformed every year for different reasons, because they do not satisfy the requirements for reproduction usage. If these animals are slaughtered without a previous fattening (reconditioning) carcasses will have some characteristics less acceptable by customers. The aim of this investigation was to evaluate the real possibilities of carcasses quality improvement in the sheep s which ended their productive and reproductive life cycle. In the investigation were included adult sheep from Merinos of Palas, Tigaie and Turcană breeds, which were reformed at the age of 7 10 years. The fattening process is carried out in the stable and grazing production system and last 65 days for each system. Control weighing and feed intake assessments have been run during our experiment, in order to estimate the fattening effects. Finally, control slaughtering was carried out in order to estimate fattening (reconditioning) effects on carcasses quality. The analysed characteristics were the carcass yield and slaughtering efficacy. Quality assessments supposed the evaluation of carcasses conformation and the fat coverage degree, using the European Union standards. Across the whole fattening period, the average gain reached 7.02 kg in Merinos of Palas sheep, which were 11.25% higher than in the Tigaie sheep and 34.61% better than in the Turcana sheep. The assessment of carcasses in relation with fat coverage degree revealed that most of them corresponded to the European classes 3 and 4, while for conformation, approximately 50% of Merinos of Palas carcasses belonged to U class. In Tigaie breed most of the carcasses belongs R and O classes (66.67%), while in Ţurcană 88.33% carcasses were allocated to O and P classes. The results confirm that fattening (reconditioning) could improve the slaughtering characteristic, carcasses quality and muscular mass in those sheep which should be reformed from the reproduction flock. Key words: Romanian sheep, meat, Tigaie, Turcana, Merinos of Palas Introduction Every year, certain number of sheep in each herd does not fulfil the production requirements. The reformation could be applied to younger animals, when they become inappropriate for reproduction, having mammary gland defects, untreatable sickness or permanent damages of dentition etc. Knowing that most of the reformed candidates are in the spring, it is not advisable to sell them in the same season, because after slaughter carcasses do not satisfies quality expectations. In order to avoid such situations, it is recommended to fatten the adult reformed sheep. The fattening period length is totally related to the animal s status prior reformation. The main purpose of reformed sheep fattening is given by the fact that during this process could be achieved a biological recovery of muscular mass and of the overall organism. Moreover, certain amounts of fat are deposited in carcasses, influencing the meat quality after slaughtering. Finally, the fattening period is justified by better physical and sensorial characteristic of the carcasses th Croatian & 5 th International Symposium on Agriculture

2 Stočarstvo Material and methods In the investigation were included adult sheep reformed in the spring of 2009, belonged to the Merinos of Palas, Tigaie and Turcan breed. The reformation was imposed by several reasons, such as: exaggerated erosion or lack of teeth, low level of milk and wool yield, sheep aged over 6 years in Merinos of Palas breed, respectively over 8 years in Tigaie and Turcana breeds. Reconditioning (fattening) included the use of the two production systems stable and grazing and lasted 65 days for each system. The provided conditions were identical for all studied groups. In stable system, the sheep were divided in breed groups and fed adlibitum, using a diet containing hay, corn silage and concentrates. Weighing was run twice daily (before and after feeding), in order to assess feed intake. In the grazing system sheep were grouped in one flock and consumed the grass on the pasture. Every morning they received supplement of 300 g/day/sheep concentrate. Finally, control slaughtering has been run, in order to measure carcass yield and slaughter efficacy dressed percentage (%). Fattening (reconditioning) effect on meat quality and yield was assessed through the usage of E.U. standards. According to these methods, the carcasses conformation is evaluated by the S.E.U.R.O.P. system, which establishes class according shape, development degree of muscles from abdomen, shoulder blade and leg of mutton. Meanwhile, the fattening rank evaluation could be done using the fat coverage degree of carcasses, assessed through a stylet incision at chop loin level, resulting classes numbered from 1 (slim carcasses) till 5 (carcasses with thick fat layer). Data processing was performed using the procedure REML (Restricted Maximum Likelihood maximum of plausibility restricted) guaranteeing the achievement of expected in the normal parameters. Results and discussion Body weight dynamics during adult sheep reconditioning. Minimal differences of weight and age have been considered when grouping was established. Production system for each breed included 25 sheep. On grazing fattening, the animals have the same accommodation and feeding conditions (same pasture and concentrates quantity). In Merinos of Palas breed, the flock fattened (reconditioned) through grazing have achieved 19.51% lower weight gain, compared to the group accommodated in stable. The differences between both groups maintained for total weight gain, carcasses average weight and dressed percentage (slaughter efficacy). Postslaughtering data analysis proved the higher effect of stable fattening (reconditioning) on meat yield. The sheep group chosen for grazing had the initial average live weight 6.05% higher than the sheep in the stable group, these differences maintained between groups but numerically decreased at 3.17%. Even if the live weight was 1.88 kg higher in the grazing sheep, the stable sheep provided carcasses kg heavier. The efficacy of stable fattening (reconditioning) is also confirmed by the values issued for dressed percentage evaluation (Table 1.). In other studies, (Zamfir et al., 2009) found 3.71% heavier carcasses for the same breed but under 90 days of fattening (reconditioning). The sheep response related to body weight gain was different during fattening, knowing they had not the same maintenance status or they belonged to different breeds (Table 1.). Fattening (reconditioning) efficacy is limited because in adult sheep de novo protein synthesis decrease as age advances and the body completed its formation (Tafta and Zuhair 1979; Mann et al., 1984; Sandu, 1993). The initial body weight at beginning fattening (reconditioning) as well as its minimal and maximal limits indicated that the slaughtering of Tigaie and Turcana sheep would not be profitable without a previous recovery, fact also proved by other researches (Pascal and Stan 2004; Tafta and Zuhair 1979; Zamfir et al., 2009). The analysis of the effect fattening (reconditioning) on the Tigaie sheep confirms the positive influence of stable system. The 45. hrvatski i 5. međunarodni simpozij agronoma 1053

3 Turcana Tigaie Merinos of Palas Grou ps Animal Husbandry evaluation of total average weight gain revealed for this version shoved 23.80% better performance, carcasses were 1.34 kg heavier and the dressed percentage was 6.23% better. Table 1. Body weight dynamics, across the period of adult sheep reconditioning Body weight dynamics Statisti Total weight c Initial weight Final weight gain Version I Reconditioning through grazing (n = 25) ± ± ± Version II Reconditioning in stable (n = 25) ± ± Slaughtering traits Carcass weight ± ± Slaughtering efficacy (%) ± ± ± 0.80 Limite Version I Reconditioning through grazing (n = 25) ± ± ± ± ± Version II Reconditioning in stable (n = 25) ± ± Version I Reconditioning through grazing (n = 25) ± ± Version II Reconditioning in stable (n = 25) ± ± ± ± ± ± ± ± ± ± ± Compared with other values specified in certain references, the average dressed percentage was close to value in the research of (Padeanu, 2009). The same assessment in Turcană breed shoved that the sheep reconditioned 65 days in stable had 27% higher weight gain than the sheep grazed, although the initial live weight was 5.17% better than in the Tigaie. The sheep reconditioned in stable produced kg heavier carcasses and the dressed percentage was 2.65% better. The differences found between the two reconditioning methods were obvious and had statistic significance for 1% and 5% levels (Table 2). All these values confirm that, despite the differences which occurred between breeds and groups, it is possible to generate probable higher quality levels of carcasses parameters after 65 days of fattening th Croatian & 5 th International Symposium on Agriculture

4 Stočarstvo Table 2. Differences and statistical significance between groups Technologi cal version Total average gain Absolute diff. Relative diff. (%) S.D. Absolut e diff. Carcass weight Relative diff. (%) S.D. Dressed weight (slaughter efficacy) Absolut e diff. (%) Relative diff. (%) Merinos of Palas V1 vs. V ** * ** Tigaie V1 vs. V ** ** ** Turcana V1 vs. V ** * * Notice: V1 reconditioned through grazing; V2 reconditioned through stable; differences; *Significant at the 0.05 level;**significant at the 0.01 level S.D S.D. significance of the Assessment of carcasses quality and conformation has been run in accordance with European regulations. Conformation class is evaluated through carcass size as well as through the profiles found in rear body region, ribs and shoulder blade. Estimation of reconditioning effect was based on the measurement thickness fat deposit, at the 3rd lumbar vertebra, then the carcasses were allocated to a class from 1 to 5 (Table 3.). Table 3. Carcasses classification according to EU standards (% of all carcasses) Category On conformation S (superior) E (excellent) U (very good) R (good) O (moderate) P (poor) On fattening rank 1 (low) 2 (light) 3 (moderate) 4 (fat) 5 (very fat) Notice: Merinos of Palas (n=8) Tigaie (n = 8) Turcana (n = 8) V1 V2 V1 V2 V1 V2 V1 reconditioning through grazing; V2 reconditioning through stable , In all groups, reconditioning in stable facilitated better biological recovery of adult sheep; therefore the carcasses presented better conformations. From all Merinos of Palas carcasses 88.33% fulfilled the requirements for U and R classes. In Tigaie breed 66.67% of carcasses belonged to R and O classes, while in Turcană sheep 50% of carcasses were classified in P conformation rank. Evaluation of fattening effect, basing on the muscular mass recovery and on fat deposits, confirmed once again that stable reconditioning allows the formation of carcasses with better sensorial and nutritional characteristic, due to lipids infiltration between muscle fascicles and muscular fibres. The carcasses classified in ranks 4 and 5 are extremely required by the customers in the Middle East, a place where Romania exports 70% of its yearly mutton production. Feed conversion ratio (FCR) is an indicator which evaluate the feeding efficacy during yield achievement. In our researches FCR presented different values, related to analysed groups and technological versions. 45. hrvatski i 5. međunarodni simpozij agronoma 1055

5 Animal Husbandry Table 4. Assessment of the feed conversion level, across the entire reconditioning period FCR (intake/kg gain) Reconditioning through grazing Reconditioning through stabulation Genotype Feed PDIN PDIE Brut PDIN PDIE UNC (g) (g) UNC (g) (g) Merinos of Palas Tigaie Turcană Thus, in permanent stable system, the lowest FCR value reached 5.83 UNC, being achieved by the Merinos of Palas breed. Compared with other studied breeds, this value was 15 % better than in the Tigaie sheep and 21.53% better than in the Turcană group (Table 4.). These differences could due to multiple factors but were mainly given by the differences related to precocity level or to meat production aptitudes, between breeds. Conclusions 1. The researches revealed better values for the studied parameters in both reconditioning system than in nonreconditioned sheep. However, higher performances have been achieved by the sheep reconditioned in stable. 2. There are obvious differences between breeds, concerning meat yield capacities, fact proved by the highest results observed in Merinos of Palas sheep carcasses (27.68 kg). 3. The absolute difference for the whole weight gain with highest values was noticed in Merinos of Palas breed (+7.02 kg), while the relative higher difference was observed in Turcană breed (27.04%). 4. In Tigaie breed, the reconditioning in stable generated an average higher weight, meaning %, the difference being significant for the statistical margin of 5%. 5. The highest values of slaughter efficacy (dressed percentage) in Merinos of Palas breed (48.20%), compared to intermediate values in Tigaie (42.66%) or to the lowest ones in Turcană (39.60%), reveal differences related to meat yield aptitudes. 6. Best results concerning carcasses conformation were achieved when reformed sheep were reconditioned in stable. There was an exception, occurred in Tigaie sheep, whose carcasses were classified in equal proportions in R and O classes, no matter the reconditioning method (grazing or stable). 7. Carcasses evaluation through the fattening rank method indicated positive and higher distribution in Merinos of Palas breed, due to the fact that 66.67% from whole stable flock filled in the characteristics specified for groups 4 and 5, while 66.77% from the grazed herd complied with the 3 and 4 classes. 8. In both reconditioning system, highest proportion of carcasses produced by Tigaie and Turcana sheep has been included in classes 2, 3 and 4; those carcasses with a thicker fat layer, corresponding to the 5th class were observed only after stable reconditioning. Acknowledgement The researches have been run using the support of the National Council of Scientific Research in Higher Education, through the project coded 676: Study of local sheep populations, reared in the NorthEast country area, in order to improve meat production th Croatian & 5 th International Symposium on Agriculture

6 Stočarstvo References Mann, T.J.L., Smith C., King J. W. B., Nicholson D., Sales D. I. (1984). Comparison of crossbred ewes from five crossing sire breeds. Animal Production 39: Morley F.H.W. (1995). Selection for economic characters in Australian Merino sheep. V. Further estimates of phenotypic and genetic parameters. Australian Journal of Agricultural Research 6 (1): Padeanu, I. (2009). Reforming breeding sheep. Ferma magazine, no. 32. [In Romanian] Pascal, C., Stan, V. (2004). The meat production and them importance for in vigoration of sheep growing. Scientific Papers, Zootehnie. 47: Pivoda, CarmenAna, Radu, R., Pascal, C. (1999). Research regarding restoration of reformed adult sheeps. Scientific Papers, Zootehnie Series. 41/42: Sandu, Gh. (1993) Engineering in sheep farming. Masthead Alutus, Bucureşti. Taftă, V., Zuhair, F.J. (1979). Comparative results regarding the intensive fattening of young and adult sheep of different races. Scientific Papers SCPCOC Palas, no. 4 Zamfir C., Jitariu D., Enciu A., Cutova N., Pivoda C.A. (2009). Optimizing the technology of reconditioningthe reformed sheep. Vol. Lucr. Ştiinţ. 52: hrvatski i 5. međunarodni simpozij agronoma 1057