Ana Maria Bezerra Oliveira Lôbo

Parâmetros genéticos de características estimadas da curva de crescimento de ovinos da raça Santa Inês

Este trabalho foi realizado com os objetivos de estudar o ajuste das funcoes de Richards, Brody, Gompertz, Von Bertalanffy e Logistica sobre a curva de crescimento de ovinos Santa Ines e estimar parâmetros geneticos para caracteristicas calculadas a partir da funcao de melhor ajuste. Foram utilizadas apenas informacoes de femeas controladas entre os anos de 1993 e 2004, na Embrapa Tabuleiros Costeiros, e entre 1981 e 2004, na Embrapa Caprinos. Para o ajuste das curvas, as analises foram realizadas separadamente para cada rebanho, utilizando-se o procedimento NLIN do software Statistical Analysis System (SAS), por meio do metodo de GAUSS. Para determinar a funcao que melhor ajustava os dados, foram utilizados os criterios de coeficiente de determinacao (R2), de quadrado medio residual (QMR) e o erro de predicao medio (EM). No rebanho da Embrapa Tabuleiros Costeiros, todas as funcoes subestimaram os pesos, a excecao da curva de Richards. Diferentemente, todas as funcoes superestimaram o peso predito para o rebanho da Embrapa Caprinos. A curva de Richards foi a que promoveu melhor ajuste nos dois rebanhos. Os valores do peso adulto e da taxa de maturacao estimados pela funcao de Richards foram de 54,38 kg e 0,00144/dia, respectivamente, para o rebanho da Embrapa Tabuleiros Costeiros, e 42,74 kg e 0,00260/dia, respectivamente, para o da Embrapa Caprinos. A funcao de Richards foi utilizada para estimar curvas individuais de crescimento dos animais. A partir destas curvas, foram estimadas varias caracteristicas de interesse economico. Os parâmetros geneticos e os componentes de (co) variância para estas caracteristicas foram estimados pelo metodo da Maxima Verossimilhanca Restrita Livre de Derivadas (DFREML), utilizando-se o software MTDFREML. As estimativas de herdabilidades direta e materna variaram, respectivamente, de 0,01 a 0,99 e de 0,00 a 0,13. E possivel alterar o padrao da curva de crescimento destes animais por meio de selecao.

Genotype effect on carcass and meat quality of lambs finished in irrigated pastures in the semiarid Northeastern Brazil

The aim of this study was to compare four genetic groups of sheep on the carcass and meat quality traits. Thirty-three contemporary and unrelated male lambs, all of single birth were used in the experiment, being thirteen from the Santa Ines (SI) breed, seven from the Brazilian Somali breed (BS), six from the Morada Nova (MN) breed and seven from the ½ Dorper - ½ Morada Nova (F1) crossbreed. The genotypes SI, BS and F1 presented similar performances in relation to hot and cold carcass weights, which values were 10.76±0.53kg and 10.46±0.52kg for SI, 9.20±0.73kg and 8.99±0.71kg for BS, and 9.35±0.73kg and 9.13±0.71kg for F1, respectively. The BS had a better hot carcass yield (47.10±0.88%) and cold carcass yield (46.00±0.87%). Better carcass conformation was observed in SI and F1 (2.73±0.12 and 2.50±0.17, respectively) while the BS presented a better finishing (3.29±0.20). The average for the rib eye area (REA) was 9.94±0.49cm2, 8.66±0.67cm2, 7.18±0.72cm2 and 9.8±0.67cm2, and for the carcass compactness index (CCI) it was 0.17±0.01kg/cm, 0.17±0.01kg/cm, 0.11±0.01kg/cm and 0.16±0,01kg/cm, for SI, SB, MN and F1, respectively. There were no significant differences between SI, BS and F1 regarding REA and CCI. Although, in general, the MN presented a relatively lower performance than the other genotypes, this breed had similar carcass yields and fat thickness when compared to SI and F1 and similar conformation and REA in comparison to the BS. Regarding meat quality, no differences were observed between genotypes, except for redness and cooking losses. It is concluded that no one group had a higher or lower performance in all traits analyzed. Moreover, for the management conditions employed in this study, there was evidence of greater specialization in meat production for genotypes SI, BS and F1 when compared to MN, although there are no substantial differences between the four groups regarding meat quality.

Intramuscular fat and fatty acid profile of muscle of lambs finished in irrigated pasture

The aim of this research was to study the differences between breeds through the analyses of the intramuscular fat content and fatty acid profile of the main local hair sheep breeds of Brazil, Morada Nova (MO), Brazilian Somali (SO) and Santa Inês (SI) and the crossbred ½ Dorper×½ Morada Nova (F1). Genetic group was a significant source of variation for intramuscular fat content, individual fatty acids, polyunsaturated fatty acid (PUFA)/saturated fatty acid (SFA) ratio, total PUFA, essential fatty acids (EFA), total n-3 and n-6 PUFA and Δ9 desaturase and atherogenic index. MO breed presented the highest values of conjugated linoleic acid, PUFA (similar to F1) and PUFA/SFA (similar to F1). MO meat had the highest proportion of EFA, despite the value was similar to F1. SO breed showed highest proportion of myristc, pentadecanoic, palmitic and palmitoleic acids in muscle, and highest Δ9 desaturase indices. In conclusion, there are differences between genetic group for the profile of fatty acids and intramuscular fat. The meat from MO lambs had better attributes of fatty acid composition with higher PUFA, PUFA/SFA ratio, EFA and total n-3 PUFA.

Do carcasses of lambs finished on commercial production systems meet market standards

This study aimed to characterize a commercial lamb finishing system using animals of undefined breed from production to slaughter by analyzing performance, carcass traits, yield of commercial cuts, and the quality and meat acceptance of different slaughter groups, as to evaluate whether this system provides the market with a standardized product. The lots were not homogeneous for yield of commercial cuts and performance and morphometric traits evaluated in vivo. The groups were heterogeneous to 75% of the 13 carcass traits evaluated, among them, hot and cold carcass weights, hot and cold carcass yields, carcass grade finishing and biological yield. There was also no uniformity for the proportion of non-carcass components, morphometry of carcass, visual appraisals, and loin traits. On the other hand, homogeneity was achieved in physico-chemical and sensory traits, except for hardness and proportion of saturated, monounsaturated and polyunsaturated fatty acids. We conclude that the commercial finishing system with the use of undefined crossbred lambs does not produce carcass and cuts standardized to the market.

Genetic parameters for rank of the Santa Inês sheep in agricultural fairs using Bayesian procedures

Abstract The aim of this study was to estimate the genetic parameters for the ability of a sheep to rank among the top three in its age category (ABI3) and for its total score (TS) on the judgement championships held in different agricultural fairs in Brazil. Data files included 3180 records referring to 1896 animals for ABI3 and 4383 records referring to 2170 animals for TS. The relationship matrix was composed by 4069 animals. Variance components were estimated fitting threshold and linear animal models for ABI3 and TS, respectively, by Bayesian analysis using the Gibbs sampler. The posterior means of the heritability and repeatability were, respectively, 0.10 ± 0.07 and 0.57 ± 0.11 for ABI3 and 0.12 ± 0.04 and 0.31 ± 0.02 for TS. The low values for the heritabilities related to these traits reveal a strong influence of the environmental factors, as the differential management offered to the animals before and during the fair. The repeatability values for ABI3 suggest high correlation among the animal classifications in different fairs. However, for TS, the observed performance has moderate confidence to be repeated over time. We conclude that although reduced, there is genetic variability for the animal’s performance in agricultural fairs. Nevertheless, due to the low heritability estimates, the expected response to direct selection for ABI3 and TS will be low.

Performance and parasite control of different genetic groups of lambs finished in irrigated pasture

The aim of this study was to compare the following four genetic groups of hair sheep: Santa Ines (SI), Morada Nova (MN), Brazilian Somali (BS), and the F1 1/2Dorper x 1/2Morada Nova crossbreed on traits related to growth and parasitic infection. Thirty-three male lambs of the same age and of simple birth, under the same pre-weaning management conditions were used in the experiment. After weaning the animals were housed in a completely randomized design in paddocks made of Panicum maximum cv. Tanzania. Along the course of the research, the performance of the four groups of sheep was observed to be negatively affected by gastrointestinal parasites, but there was a genotype effect to the average daily weight gain (ADWG), where the SI and F1 genotypes presented higher values. The effects of genotype, time and genotype x time interaction were significant in weight and corporal score (CS) measurements. The BS lambs had the highest CS values throughout the experiment despite not presenting greater weight gain when compared to the SI and F1 breeds. There were also significant effects of time and genotype x time interaction for packed cell volume (PCV) and FAMACHA© score (FAM) and only the time effect was significant in the total number of eggs per gram (EPG) and total plasma protein (TPP). The MN lambs showed higher PCV values and unlike the other groups, presented a FAMACHA© score below 3 and PCV above 23% even having a higher EPG tendency, especially in the initial phase, indicating a possible higher resilience to infection caused by gastrointestinal parasites.