Sônia Maria Pinheiro de Oliveira

Efeito do estresse climático sobre os parâmetros produtivos e fisiológicos de ovinos Santa Inês mantidos em confinamento na região litorânea do Nordeste do Brasil

A study was conducted to determine the effect of environmental stress on physiological criteria of feedlot sheep. Treatments consisted of two different housing conditions (shade and no shade) and two levels of concentrate in the diet: high concentrate (70% of concentrate and 30% of roughage-70C:30R); low concentrate (30% of concentrate and 70% of roughage-30C:70R). Animals raised under shade and fed a high concentrate diet (70C:30R) had greater dry mater intake (1258 g/animal/day) and crude protein (0.8% of body weight (BW) and 18 g/BW0.75), as well as weight gain (247 g/animal/day). Air temperature in the afternoon was 30.6:C, under shade, and 32.1:C, under sun and values of temperature humidity index(THI), 82.3 and 81.1, respectively. Animals fed more concentrate (70C:30R) had also higher respiratory frequency (RF), either raised under shade (87 mov/min) or under the sun (71 mov/min.). Rectal temperature (RT) was higher in the afternoon (39.1:C) than in the morning (38.9:C), but animals raised under shade and fed diets with 70% concentrate (70C:30R) had the highest value of RT (39.3:C). Regardless of type of housing conditions, the animals that received more concentrate (70C:30R) had greater rectal temperature (39.2:C) than those fed a diet with less concentrate (30C:70R) (38.8:C). Therefore, the type of diet influenced the response of the animals to housing conditions. Moreover, Santa Ines sheep are susceptible to environmental stress because had lower performance when raised under no shade.

Identification of selection signatures in livestock species

The identification of regions that have undergone selection is one of the principal goals of theoretical and applied evolutionary genetics. Such studies can also provide information about the evolutionary processes involved in shaping genomes, as well as physical and functional information about genes/genomic regions. Domestication followed by breed formation and selection schemes has allowed the formation of very diverse livestock breeds adapted to a wide variety of environments and with special characteristics. The advances in genomics in the last five years have enabled the development of several methods to detect selection signatures and have resulted in the publication of a considerable number of studies involving livestock species. The aims of this review are to describe the principal effects of natural/artificial selection on livestock genomes, to present the main methods used to detect selection signatures and to discuss some recent results in this area. This review should be useful also to research scientists working with wild animals/non-domesticated species and plant biologists working with breeding and evolutionary biology.

Efeitos genéticos aditivos e não-aditivos para características produtivas e reprodutivas em vacas mestiças Holandês × Gir

A partir de registros de genealogia e controle leiteiro e reprodutivo fornecidos pela Associacao Brasileira dos Criadores de Girolando, foram estimados os efeitos de diferenca genetica aditiva entres as racas Holandesa e Gir, de dominância e de recombinacao, alem das herdabilidades e repetibilidades, para as caracteristicas producao de leite por lactacao (PL), producao de leite ate os 305 dias de lactacao (PL305), duracao da lactacao (DL), intervalo de partos (IDP), idade ao primeiro parto (IPP) e producao de leite por dia de intervalo de partos (PL/IDP). Foram utilizados 4.805 registros de PL, PL305 e DL e 2.222, 1.408 e 2.363 registros de IDP, IPP e PL/IDP, respectivamente. Analises unicaracteristicas foram realizadas considerando os efeitos de diferenca genetica aditiva entre as racas, de dominância e de recombinacao como covariaveis. As estimativas para a diferenca genetica aditiva entre as duas racas foram significativas para todas as caracteristicas, exceto para o IDP, e foram estimadas em 3.115 ± 273 kg, 2.574 ± 226 kg, 98 ± 13 dias, -236 ± 67 dias e 7,5 ± 0,9 kg/dia para PL, PL305, DL, IPP e PL/IDP, respectivamente. Os efeitos de dominância (heterose) tambem foram significativos para todas as caracteristicas, exceto para a DL. Foi verificada significativa perda por recombinacao para PL e PL305. As estimativas de herdabilidade foram de 0,25 ± 0,05, 0,21 ± 0,04, 0,12 ± 0,04, 0,05 ± 0,05, 0,33 ± 0,09 e 0,21 ± 0,07 para PL, PL305, DL, IDP, IPP e PL/IDP, respectivamente, enquanto as estimativas de repetibilidade foram de 0,49 ± 0,05; 0,47 ± 0,04; 0,18 ± 0,04; 0,09 ± 0,06; e 0,37 ± 0,07 para PL, PL305, DL, IDP e PL/IDP, respectivamente.

Tendências genéticas para características relacionadas à velocidade de crescimento em bovinos Nelore na região nordeste do Brasil

The objectives of this work were to estimate the genetic parameters and the genetic trends of the direct and maternal effects for the trait days to gain 160 kg (D160) in the pre-weaning period, and of the direct effect for the trait days to gain 240 kg (D240) in the post-weaning period, of animals of Nellore breed, born from 1965 to 2001 in the Northeast region of Brazil. The analyses were carried out using the MTDFREML software. For D160 the model included the direct and maternal genetic random effects and maternal permanent environmental effect, besides the fixed effects of contemporary group and the covariate age of dam at calving, assuming the covariance between maternal and direct effect equal to zero (sam=0). For D240, the same fixed effects were considered, however, just the direct genetic effect as random. The genetic trends were estimated by linear regression of the breeding values on year of birth of the animals. The direct and maternal heritabilities for D160, respectively, were 0.12 ± 0.01 and 0.07 ± 0.02. The direct heritability for D240 was 0.16 ± 0.02. The genetic trends of the direct effects were significant, with estimated values of -0.14 and -0.41 days/year for D160 and D240, respectively. The genetic trend of the maternal effect for D160 was significant and equal to -0.0037 days/year. The genetic trends were favorable, however, inferiors the potential gain.

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.

Estimação de funções de covariância para características de crescimento da raça Tabapuã utilizando modelos de regressão aleatória

In order to estimate covariance functions by using random regression models on Legendre polynomials, 35,732 weight records from birth to 660 days of age of 8,458 animals of Tabapua cattle were used. The models included: as random effects, direct additive genetic effect, maternal effect, and animal and maternal permanent environmental effets; contemporary groups were included as fixed effects; and as covariables, animal age at weighing and age of dam at calving (linear and quadratic effects) and on age at weighing,, the orthogonal Legendre polynomial (cubic regression) was considered to model the mean curve of the population. Residuals effects were modeled considering seven classes of variance. The models were compared by Akaike criterion and Bayesian information criterion. The best model showed orders 4, 3, 6, and 3 for maternal and direct additive genetic effect, and maternal and animal permanent enviroment, respectively. Estimates of (co)variance and heritability obtained with the bi-trait and random regression models were similar. The heritability estimates for direct additive genetic effect obtained by the random regression models increased from birth (0.15) to 660 days of age (0.45). The greatest estimates of maternal heritability were obtained for weights measured right after birth. In general, the genetic correlation estimates were moderate to high, and they decreased as the distance between weights increased. Selection for higher weights at any age will promote weight gain from birth to 660 days of age.

Efeitos genéticos aditivos e não-aditivos em características de crescimento, reprodutivas e habilidade materna em ovinos das raças Santa Inês, Somalis Brasileira, Dorper e Poll Dorset

Additive genetic, dominance and recombination effects in breedings among Santa Ines (SI), Brazilian Somali (So), Dorper (Do) and Poll Dorset (Po) breeds were estimated for growth, reproductive and maternal hability traits. Data were obtained from Gaasa e Alimentos LTDA, a company that participates on the Programa de Melhoramento Genetico de Caprinos e Ovinos (GENECOC) coordinated by Embrapa Caprinos. Initially, 3,573 records were analyzed using the MIXED procedure of the statistical package SAS (1999). The analyses were carried out considering the effects of additive genetic difference among breeds, dominance and recombination effects. Birth weight was mainly influenced by additive genetic effects, while weaning weight and pre-weaning weight gain were influenced by non-additive genetic effects. Direct heritability estimates for birth weight was moderate indicating that there is genetic variability believable to be exploited by individual selection. In the same way, heritability estimates for the traits age at first lambing and litter total weight at birth indicated the existence of genetic variability to obtain genetic gains through selection. Genes of the Poll Dorset and Dorper breeds had an important role for a better growth performance, therefore, these breeds can be indicated as sires in the terminal breeds. The use of F1 Santa Ines x Brazilian Somali females on crossbreeding with Poll Dorset rams can lead to a better reproductive efficiency.

Características físico-mecânicas do couro de ovinos mestiços Santa Inês e Texel

Objetivou-se, neste estudo, avaliar as caracteristicas fisico-mecânicas de couros de ovinos mesticos F1 provenientes de cruzamentos de ovelhas deslanadas sem raca definida (SRD) com carneiros das racas lanada Texel (TE) e deslanada Santa Ines (SI). Foram avaliadas 22 peles de borregos abatidos com idade media de 240 dias e peso corporal de 21,93 ± 4,38 e 20,91 ± 3,40 kg, respectivamente, para os mesticos de TE e SI. Apos a esfola, as peles foram pesadas, conservadas por salmouragem e salga e avaliadas no curtume. Inicialmente, foram curtidas ao cromo-estagio de wet blue e, posteriormente, dos couros semi-acabados, foram retirados do lado direito corpos-de-prova nas posicoes paralela e perpendicular ao eixo crânio-caudal das regioes paleta, anca e ventre, para a determinacao dos ensaios fisico-mecânicos de resistencia a tracao e ao rasgamento progressivo. O delineamento experimental para analises dos dados foi o de parcelas subdivididas, tendo como parcelas dois grupos geneticos e como subparcelas o fatorial 2 x 3 (duas posicoes e tres regioes), com tres repeticoes, sendo os valores medios comparados pelo teste de Tukey. Os couros dos ovinos deslanados mesticos SI apresentaram maior resistencia aos ensaios de tracao e rasgamento progressivo que o couros dos animais mesticos Texel, havendo, em ambos os grupos, diferencas significativas de espessura e resistencia entre as diferentes regioes dos couros estudados. Concluiu-se que os couros oriundos do cruzamento do ovino lanado Texel com ovelhas SRD apresentam menor qualidade industrial que os couros de animais mesticos deslanados Santa Ines.

Ganho de peso e rendimento de carcaça de cordeiros mestiços Texel e Santa Inês x SRD em sistema de manejo semi intensivo

A research was conducted at the Experimental Field Station Vale do Curu of the Federal University of Ceará to evaluate the growth rate and carcass traits of crossbred lambs born from crioula tropical hair ewes (SRD) mated with Texel and Santa Ines rams. 33 lambs being 17 crossbred Texel X SRD ( eigth entire male lambs and seven female lambs) and 16 crossbred Santa Inês X SRD (11 entire male lambs and five female lambs) were studied. Lambs were weaned at 90 days old and were raised in a semi-intensive system production. Crossbred Texel lambs were sheared before slaugther. Growth rate was studied by measuring the live bodyweight each 15 days from born to eigth months old, age estimated as good to slaughter the male lambs. The weigth and carcass yield were evaluated. Data analyses show that the crossbred Texel lambs have better growing performance and higher daily weigth gain than Santa Inês crossbred lambs, but significant differences of sire breed were not detected in the hot and cold carcass yield. It was concluded that crossbreeding of crioula tropical hair ewes with Texel rams may be beneficial for growth performance of lambs in a industrial breeding programme. More studies are necessary to evaluate the effect of wool on sheep raising on tropical condition.Com o trabalho teve-se o objetivo de avaliar o ganho de peso e as caracteristicas de carcaca de cordeiros mesticos oriundos do cruzamento de carneiros da raca lanada Texel e deslanada Santa Ines com ovelhas deslanadas sem padrao racial definido-SRD. Foram avaliados 33 cordeiros de ambos os sexos, sendo 17 cordeiros mesticos Texel x SRD (8 machos inteiros e 7 femeas e 16 mesticos Santa Ines x SRD (11 machos inteiros e 5 femeas). Os cordeiros foram desmamados em media com 90 dias de idade e 11,5 kg de peso vivo e mantidos juntos em sistema de manejo semi-intensivo. O ganho de peso foi estimado atraves de pesagens periodicas a cada 15 dias, do nascimento ate os oito meses de idade, periodo estimado para o abate dos machos. Os cordeiros mesticos Texel foram tosados ao final do experimento para a retirada da la afim de evitar a influencia desta no peso e rendimento da carcaca. A analises dos dados mostraram que os cordeiros mesticos Texel apresentaram maiores pesos corporais ao nascimento e aos oito meses de idade, com ganhos de peso diario significativamente superior (P< 0,05) do desmame ao peso final. O peso final dos cordeiros mesticos Texel foi de 23,70 ± 3,8 kg e dos Santa Ines de 20,7 ± 2,2 kg com ganhos medios diarios, do nascimento ate o peso final, de 83 e 72 g, respectivamente, valores inferiores ao esperado em ambos grupos geneticos. Embora tenha sido obtido um maior peso corporal dos cordeiros mesticos Texel ao abate, nao houve influencia do genotipo nos rendimentos de carcaca quente e fria dos animais. Conclui-se que a utilizacao de carneiros da raca Texel em cruzamento com femeas deslanadas SRD na regiao nordeste do Brasil, resulta em maiores ganhos de peso de suas crias, quando comparado com os da raca local Santa Ines, porem, nao ha efeito do genotipo no rendimento da carcaca dos animais. Desta forma, o uso de reprodutores lanados com ovelhas deslanadas, nas condicoes em que foram feitas as observacoes, pode se justificar somente em cruzamento terminal ou industrial e com ovelhas SRD. Maiores estudos devem ser realizados para avaliar o efeito da prducao de la sobre o desempenho dos animais nas condicoes de clima do Nordeste.

Utilização da nebulização e ventilação forçada sobre o desempenho e a temperatura da pele de suínos na fase de terminação

O experimento foi realizado com o objetivo de avaliar os efeitos da nebulizacao e ventilacao forcada sobre o desempenho e a temperatura da pele de suinos na fase de terminacao. Utilizaram-se 137 animais (Landrace x Large White x Duroc) machos castrados e femeas, distribuidos em um delineamento de blocos ao acaso, com dois tratamentos de oito repeticoes por tratamento, com media de oito animais/baia. Os tratamentos utilizados foram: T1 = sem nebulizacao de agua e ventilacao forcada e T2 = com nebulizacao de agua e ventilacao forcada. Durante o periodo experimental, a temperatura media observada foi de 26,32oC (variando de 23,32 a 30,72oC) e a umidade relativa do ar media, de 64,5%. Os resultados nao demonstraram diferencas significativas entre os tratamentos utilizados para as variaveis ganho de peso medio diario, consumo de racao medio diario e conversao alimentar. Entretanto, a nebulizacao de agua associada a ventilacao forcada apresentou menores valores de temperatura da pele, indicando melhor conforto aos animais. Nao e necessario o uso de nebulizacao e ventilacao forcada em instalacoes para suinos na fase de terminacao, pois, apesar da melhoria no conforto dos animais (temperatura da pele), nao trouxe beneficio sobre o desempenho dos mesmos.