Productive response of hair ewes crossed with Damara and Dorper and growth of their lambs / Resposta produtiva de ovelhas de cabelo cruzado com Damara e Dorper e crescimento de seus cordeiros

Profitability of sheep production depends on the reproductive response of ewes and growth of their lambs, which can be improved through the ram genotype. The aim of this study was to evaluate the reproductive response of Blackbelly (Bb), Pelibuey (Pb), Katahdin (Kat) and Dorper (Dor) ewes crossed with Damara (Dam) and Dor rams and the growth of their offspring. To measure percentage of single and multiple lambings (MLP), 234 Bb, Pb, Kat and Dor ewes were used. To measure lamb growth, the offspring of 86 Bb x Pb (BbPb) ewes and 73 Kat x Dor (KatDOR) ewes were used. Four Dor x BbPb, six Dam x BbPb and six Dam x KatDor lambs were slaughtered for carcass assessment. MLP was analyzed with the CATMOD procedure considering the factors age and breed. Lamb growth data were analyzed with the MIXED procedure, and those of carcass characteristics with the GLM procedure of SAS, using weight at slaughter as covariable. MLP was higher (P<0.05) in Bb than in Dor. The Dor x BbPb lambs were heavier (P<0.05) at birth than Dam x BbPb. Of the lambs from single and multiple births, the KatDor lambs were heavier (P<0.05) at birth than BbPb lambs. The female lambs of Dor rams had higher (P<0.05) weight gain after weaning than those of Dam rams. Carcass dressing, subcutaneous fat, and primal cut yield were not different (P>0.05) by effect of ram breed. It is concluded that Bb ewes are more prolific than Dor ewes; male lambs of Dam rams had post-weaning growth response and carcass yield similar to those of Dor rams, although the female lambs of Dor rams were heavier than those of Dam rams.(AU)

Rentabilidade da produção de ovinos depende da resposta reprodutiva de ovelhas e do crescimento de seus cordeiros, o que pode ser melhorado por meio do genótipo masculino. O objetivo deste estudo foi avaliar o desempenho reprodutivo de ovinos Blackbelly (Bb), Pelibuey (Pb), Katadin (Kat) e Dorper (Dor) e o crescimento de cordeiros com carneiros Damara (Dam) e Dor. Para medir a porcentagem de partos simples e múltiplas (MLP), foram utilizados 234 ovelhas Bb, PB, Kat e Dor. Para medir o crescimento dos cordeiros, foram utilizadas 86 ovelhas Bb x Pb (BbPb) e 73 Kat x Dor (KatDOR). Quatro cordeiros Dor x BbPb, seis Dam x BbPb e seis Dam x KatDor foram sacrificados para avaliação de carcaça. MLP foi analisada com o procedimento CATMOD, considerando-se fatores como idade e raça. Dados de crescimento do cordeiro foram analisados com o procedimento MIXED, e as de características de carcaça com o procedimento GLM do SAS, utilizando-se peso ao sacrifício como covariável. MLP foi maior (P<0.05) em Bb do que em Dor. Os cordeiros Dor x BbPb foram mais pesados (P<0.05) no nascimento do que Dam x BbPb. Em partos simples e múltiplos, os cordeiros de ovelhas KatDor foram mais pesados (P<0.05) no momento do nascimento de cordeiros BbPb. As cordeiras de carneiros Dor apresentaram maior (P<0.05) ganho de peso após o desmame do que as de carneiros Dam. O rendimento de carcaça, a espessura da gordura subcutânea e o rendimento de corte primal não foram diferentes por efeito da raça de carneiro. Conclui-se que as ovelhas Bb são mais prolíficas do que as ovelhas Dor; cordeiros de carneiros Damara tiveram resposta de crescimento pós-desmame e rendimento de carcaça semelhantes aos dos carneiros Dor, embora Dorper cordeiras fossem mais pesadas do que as de Damara.(AU)

Productive response of hair ewes crossed with Damara and Dorper and growth of their lambs / Resposta produtiva de ovelhas de cabelo cruzado com Damara e Dorper e crescimento de seus cordeiros

Profitability of sheep production depends on the reproductive response of ewes and growth of their lambs, which can be improved through the ram genotype. The aim of this study was to evaluate the reproductive response of Blackbelly (Bb), Pelibuey (Pb), Katahdin (Kat) and Dorper (Dor) ewes crossed with Damara (Dam) and Dor rams and the growth of their offspring. To measure percentage of single and multiple lambings (MLP), 234 Bb, Pb, Kat and Dor ewes were used. To measure lamb growth, the offspring of 86 Bb x Pb (BbPb) ewes and 73 Kat x Dor (KatDOR) ewes were used. Four Dor x BbPb, six Dam x BbPb and six Dam x KatDor lambs were slaughtered for carcass assessment. MLP was analyzed with the CATMOD procedure considering the factors age and breed. Lamb growth data were analyzed with the MIXED procedure, and those of carcass characteristics with the GLM procedure of SAS, using weight at slaughter as covariable. MLP was higher (P0.05) by effect of ram breed. It is concluded that Bb ewes are more prolific than Dor ewes; male lambs of Dam rams had post-weaning growth response and carcass yield similar to those of Dor rams, although the female lambs of Dor rams were heavier than those of Dam rams.

Rentabilidade da produção de ovinos depende da resposta reprodutiva de ovelhas e do crescimento de seus cordeiros, o que pode ser melhorado por meio do genótipo masculino. O objetivo deste estudo foi avaliar o desempenho reprodutivo de ovinos Blackbelly (Bb), Pelibuey (Pb), Katadin (Kat) e Dorper (Dor) e o crescimento de cordeiros com carneiros Damara (Dam) e Dor. Para medir a porcentagem de partos simples e múltiplas (MLP), foram utilizados 234 ovelhas Bb, PB, Kat e Dor. Para medir o crescimento dos cordeiros, foram utilizadas 86 ovelhas Bb x Pb (BbPb) e 73 Kat x Dor (KatDOR). Quatro cordeiros Dor x BbPb, seis Dam x BbPb e seis Dam x KatDor foram sacrificados para avaliação de carcaça. MLP foi analisada com o procedimento CATMOD, considerando-se fatores como idade e raça. Dados de crescimento do cordeiro foram analisados com o procedimento MIXED, e as de características de carcaça com o procedimento GLM do SAS, utilizando-se peso ao sacrifício como covariável. MLP foi maior (P<0.05) em Bb do que em Dor. Os cordeiros Dor x BbPb foram mais pesados (P<0.05) no nascimento do que Dam x BbPb. Em partos simples e múltiplos, os cordeiros de ovelhas KatDor foram mais pesados (P<0.05) no momento do nascimento de cordeiros BbPb. As cordeiras de carneiros Dor apresentaram maior (P<0.05) ganho de peso após o desmame do que as de carneiros Dam. O rendimento de carcaça, a espessura da gordura subcutânea e o rendimento de corte primal não foram diferentes por efeito da raça de carneiro. Conclui-se que as ovelhas Bb são mais prolíficas do que as ovelhas Dor; cordeiros de carneiros Damara tiveram resposta de crescimento pós-desmame e rendimento de carcaça semelhantes aos dos carneiros Dor, embora Dorper cordeiras fossem mais pesadas do que as de Damara.

Distribución de partos por estación en ovejas de razas de pelo y cruces en un ambiente tropical húmedo / Lambing distribution by season in hair sheep and crosses under a humid tropical environment

Datos de 4203 registros de parición desde 1997 a 2005 provenientes de tres grupos raciales de ovejas de pelo, se utilizaron para determinar la distribución de partos en condiciones de un sistema de apareamiento continuo a través del año. Los grupos raciales fueron Blackbelly (BB), F1 Pelibuey x Blackbelly (F1 P x BB) y un grupo de hembras híbridas denominado “Cruce” (Cruce), resultado del apareamiento de los grupos indicados anteriormente con carneros Dorper y Katahdin. El manejo reproductivo incluyó la presencia continua del macho. Las ovejas fueron expuestas a un apareamiento continuó con carneros adultos. Las épocas climáticas de partos fueron: seca (febrero a abril), lluvias uno (mayo a julio), lluvias dos (agosto a octubre) y nortes (noviembre a enero). El número de partos dentro de cada grupo racial fue primíparas y multíparas. Los datos se analizaron con la prueba de Ji-cuadrado. La distribución de partos fue diferente (P<0,01) entre épocas climáticas de parto. La frecuencia de partos fue mayor durante la época de nortes con relación a las otras épocas climáticas. La época climática influyó (P<0,01) sobre la frecuencia de partos en los grupos raciales estudiados. Los tres grupos raciales estudiados mostraron mayor frecuencia de partos en nortes que en las otras épocas. Las ovejas primíparas F1 P x BB y Cruce tuvieron menor frecuencia de partos (P<0,01) en lluvias que en las otras épocas. Las ovejas multíparas de los grupos BB, F1 P x BB y Cruce tuvieron mayor frecuencia de partos en nortes que en las otras épocas. La eficiencia de parición de ovejas de pelo en condiciones de apareamiento continuo muestra variación estacional, las ovejas primíparas y multíparas mostraron un pico de parición en la época de nortes. La época climática afecta la frecuencia de parición en los grupos raciales estudiados.

Data of 4203 lambing records from 1997 to 2005 of three breed groups of hair sheep were used to determine the lambing distribution under a continuous breeding system throughout the year. The breed groups were Blackbelly (BB), F1 Pelibuey x Blackbelly (F1 P x BB) and a group of females hybrids denominated “Cruce” (Cruce) as a result of groups crossings above indicated with Dorper and Katahdin rams. Reproductive management included the continuous presence of the male. Ewes were exposed to continuous breeding with adult rams. The climatic lambing season were: dry (February to April), rainfall one (May to July), rainfall two (August to October) and rainfall and winds (November to January). The parity orders within each breed group were primiparous and multiparous. Data were analysed with the Chi- square test. The lambing distribution was different (P<0.01) among climatic lambing seasons. The lambing frequency was greater during the rainfall and wind season than the others climatic seasons. Climatic season influenced (P<0.01) the lambing frequency in the breed groups studied.The three breed groups studied showed higher lambing frequency in rainfall and wind season than the other seasons. The F1 P x BB and Cruce primiparous ewes had lower lambing frequency (P<0.01) in rainfall than the other seasons. The BB, F1 P x BB and Cruce multiparous ewes had higher lambing frequency (P<0.01) in rainfall and wind season than the other seasons. The lambing performance of hair sheep under a continuous breeding system had seasonal variation, the primiparous and multiparous ewes showed a peak lambing in rainfall and wind seasons. The climatic seasons affected the lambing frequency in the breed groups studied.

Aromatase gene and its effects on growth, reproductive and maternal ability traits in a multibreed sheep population from Brazil

We determined the polymorphism C242T of the aromatase gene (Cyp19) and its allelic frequency, as well as the effect of the variants on productive and reproductive traits in 71 purebred Santa Inês sheep, 13 purebred Brazilian Somali sheep, nine purebred Poll Dorset sheep, and 18 crossbred 1/2 Dorper sheep. The animals were genotyped using the PCR-RFLP technique. The influence of the animal's genotype on its performance or on the performance of its lambs was analyzed by the least square method. Another factor assessed was the importance of the animal's genotype in analysis models for quantitative breeding value estimates, and whether there were differences among the averages of breeding values of animals with different genotypes for this gene. In the sample studied, no AA individuals were observed; the AB and BB frequencies were 0.64 and 0.36, respectively. All Brazilian Somali sheep were of genotype BB. All 1/2 Dorper BB animals presented a lower age at first lambing, and the Santa Inês BB ewes presented a lower lambing interval. In these same genetic groups, AB ewes presented higher litter weight at weaning. This is evidence that BB ewes have a better reproductive performance phenotype, whereas AB ewes present a better maternal ability phenotype. However, in general, animals with genotype AB presented better average breeding values than those with genotype BB.

Genetic parameters for growth, reproductive and maternal traits in a multibreed meat sheep population

The genetic parameters for growth, reproductive and maternal traits in a multibreed meat sheep population were estimated by applying the Average Information Restricted Maximum Likelihood method to an animal model. Data from a flock supported by the Programa de Melhoramento Genético de Caprinos e Ovinos de Corte (GENECOC) were used. The traits studied included birth weight (BW), weaning weight (WW), slaughter weight (SW), yearling weight (YW), weight gain from birth to weaning (GBW), weight gain from weaning to slaughter (GWS), weight gain from weaning to yearling (GWY), age at first lambing (AFL), lambing interval (LI), gestation length (GL), lambing date (LD - number of days between the start of breeding season and lambing), litter weight at birth (LWB) and litter weight at weaning (LWW). The direct heritabilities were 0.35, 0.81, 0.65, 0.49, 0.20, 0.15 and 0.39 for BW, WW, SW, YW, GBW, GWS and GWY, respectively, and 0.04, 0.06, 0.10, 0.05, 0.15 and 0.11 for AFL, LI, GL, LD, LWB and LWW, respectively. Positive genetic correlations were observed among body weights. In contrast, there was a negative genetic correlation between GBW and GWS (-0.49) and GBW and GWY (-0.56). Positive genetic correlations were observed between AFL and LI, LI and GL, and LWB and LWW. These results indicate a strong maternal influence in this herd and the presence of sufficient genetic variation to allow mass selection for growth traits. Additive effects were of little importance for reproductive traits, and other strategies are necessary to improve the performance of these animals.