Morada Nova breed has a low effective herd, and its white variety is in risk of extinction. The selection of individuals based on breed standard without correlation with productive aptitude is predominant today. We believe that the best way to rescue this valuable genetic resource is to describe its productive potential for commercial use. Thus, this study described the meat production potential of Morada Nova lambs through morphological and zoometric data, performance and carcass characteristics. Twenty-four non-castrated male lambs from two genetic groups were used: Morada Nova red (MNR) and crossbreed Morada Nova (red x Morada Nova white-MNF1) distributed in a completely randomized design. Univariate and multivariate analysis were used. The yields of commercial cuts and the physicochemical characteristics and qualitative measurements of the carcass were similar between the genetic groups. Seven of the 28 characteristics of the carcass were greater in MNF1 lambs. The chest height, rump height and anamorphosis index showed to be important variables in the choice of MN lambs with meat production potential. Based on factor and hierarchical cluster analysis, the Morada Nova beef morphometric index (MNBMI) was created. Both of groups have high thoracic development, ability to produce meat, weight gain, feeding efficiency and breathing capacity, infusing greater rusticity and adaptability; however, the application and validation of the developed index showed superiority for meat production in the crossed lambs. Thus, the MNF1 lambs are a sustainable option for sheep production in drylands.

No abstract

No abstract

No abstract

The objective of this study was to characterize the meat production potential of Morada Nova lambs from different genetic groups using morphological and zoometric data, performance and carcass characteristics. A total of 24 non-castrated male lambs from two genetic groups were used: Morada Nova red (MNR) and Morada Nova F1 red x Morada Nova white (MNF1) breed, with an initial mean body weight of 16.9 ± 3.43 kg and an average age of four months were distributed in a completely randomized design. Evaluations of morphometric data and zoom indices, performance and carcass characteristics were measured and calculated. Univariate and multivariate techniques were used to differentiate and reduce the number of variables, to group them and then develop and validate a sheep meat production index. Only 12 differences in the 29 morphometric measurements and zoometric indices analyzed were observed (P < 0.05). Furthermore, only 7 of the 28 quantitative and qualitative characteristics of the carcass were greater (P < 0.05) in MNF1 lambs. The yields of commercial cuts and the physical-chemical characteristics and qualitative measurements of the carcass were similar (P > 0.05) between the genetic groups. All groups of variables, except the cut yield, have discriminatory power (P < 0.05) with the highest classification percentages for body morphometry (91.3%) and zoometric indices (95.7%). The four identified factors, which together explain more than 85.0% of the total data variation, were renamed in the following order of importance: morpho-economic (38.5%), morpho-productive (18.8%), morpho-commercial (17.5%), and equilibrium (11.0%). The heat map showed the suitability in the morpho-commercial and morpho-economic factors for MNF1 lambs, while the MNR lambs showed emphasis for the equilibrium factor. Thus, the Sheep Meat Morphometric Index (SMMI) resulted in the following equation SMMI =\(\frac{\text{A}\text{I} \times 0.771 + \text{C}\text{H} \times 0.759 + \text{R}\text{H} \times 0.878 + \text{T}\text{P}\text{R}\text{I} \times 0.876 + \text{B}\text{I} \times 0.550 + \text{C}\text{W} \times 0.905}{100}\) In which: AI is the anamorphosis index; CH is chest height; RH is rump height; TPRI is the thoracic perimeter relation index; BI is body index; and CW is chest width. The application and validation of the developed index showed superiority (P < 0.001) for meat production in the crossed lambs. MNR and MNF1 lambs have high thoracic development, compact character and aptitude for meat production. Lambs crossed between genetic groups of the MN breed are another sustainable option for sheep production in drylands. It is recommended that the SMMI be used as a tool for morpho-productive selection criteria in breeding programs in the MN breed, as well as other small native breeds.