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

Effect of Lighting Programs on Performance, Carcass and Production Costs of Arian Broilers

. Light is an environmental factor, which has profound influences on broilers performance and frequently overlooked management practices. This study was conducted to compare the effects of different lighting programs on growth, carcass parts and economical performance using 320 one day–old broilers (Arian 386) in completely randomized design with 4 treatments and 8 replicates per each treatments (10 birds for each replicate). The four lighting schedules under study were: 1- continuous lighting (control), 2- decreasing-sudden increasing lighting, 3- decreasing-gradual increasing lighting and 4- intermittent lighting (1 light: 3 dark). Feed intake, body weight, feed conversion ratio, mortality and production index of birds raising under different lighting schedules were compared during six weeks of experimental carrier. Final body weight and total feed consumption were the same for all birds regardless of lighting schedules applied (P>0.05). Intermittent lighting significantly improved feed conversion ratio and decreased mortality rate compared to other lighting schedules (

Identification of candidate genes for blood metabolites in Iranian chickens using a genome-wide association study

<p>1. In order to identify loci associated with metabolic traits, a genome-wide association study was carried out in a chicken F2 population derived from a reciprocal cross between Iranian Urmia indigenous chickens and Arian broiler line using Illumina 60K Chicken single nucleotide polymorphism (SNP) BeadChip.</p> <p>2. Six traits including plasma level of triglycerides (TGs), cholesterol (Chol), glucose (Glu), total protein, albumin (Alb) and globulin (Glo) were recorded. The association between the identified SNPs and metabolic traits was estimated by general linear model (GLM) and compressed mixed linear model (CMLM).</p> <p>3. A total of 38 SNPs were identified at the genome-wide significant and suggestive levels, of which 5 SNPs reached a 5% Bonferroni genome-wide significance (<i>P</i> < 2.58E-6) for TG, Alb and Glo through CMLM, and 21 SNPs were significantly associated with TG, Chol, Glu, Alb and Glo through GLM.</p> <p>4. Gene ontology showed that these SNPs were located within or near the candidate genes responsible for metabolic traits.</p> <p>5. In conclusion, the identified candidate genes provided novel information for molecular mechanisms underlying metabolic traits. These findings are important in marker-assisted selection in the chicken breeding scheme.</p

Efeito da herança citoplasmática sobre características de produção em ovinos da raça merino Effects of cytoplasm inheritance on production traits of merino sheep

Para avaliar os efeitos de linhagem citoplasmática (LCT), foram usadas medidas de peso corporal (PC, n = 707) e peso de velo sujo (PVo, n = 703) de fêmeas e medidas de diâmetro das fibras de lã (DF, n = 350) de machos ovinos da raça Merino com um ano de idade. As informações de pedigree incluíram 3645 animais e, em média, 10 gerações. Foram usados a metodologia da Máxima Verossimilhança Restrita e o modelo animal que incluiu efeito genético direto, efeitos direto e de LCT, efeitos direto, materno e de LCT e efeitos direto, materno e permanente de meio materno. Efeitos fixos de ano e época de nascimento foram incluídos em todos os modelos. O teste da razão das verossimilhanças foi usado para comparar os modelos matemáticos. Não houve diferenças entre os modelos em que se incluiu ou não o efeito de LCT, indicando que os efeitos citoplasmáticos não foram importantes para as características estudadas. Para PC, os resultados indicaram haver confundimento parcial entre os efeitos genético aditivo materno, permanente de meio materno e de LCT. A importância relativa dos efeitos aditivos maternos foi maior para a característica PC (24,2%, no modelo mais simples; 7,9% no modelo mais completo) que para PVo e DF. A importância relativa dos efeitos aditivos diretos foi também maior para PC (24,5 a 37,1%, para os diferentes modelos), seguido de PVo (de 19,5 a 24,6%) e DF (de 16,3 a 21,0%). As estimativas de herdabilidade indicam que a seleção pode ser realizada com sucesso para as características peso corporal, peso de velo sujo e diâmetro das fibras de lã dos ovinos da raça Merino.<br>To evaluate the effects of cytoplasm lineage (CL) the body weight (BW, n = 707) and greasy fleece weight (FW, n = 703) of females and fiber wool diameter (FD, n = 350 males) of males sheep from yearling Merino sheep were used. The pedigree information included 3,645 animals and an average of 10 generations. The Maximum Restricted Likelihood methodology and animal models that included the direct genetic, direct and CL effects, direct, maternal and CL effects and direct, maternal, environmental maternal effects were used. Fixed effects of year and season of birth were included in all models. The likelihood ratio test was used for comparisons between the models. There were no differences between models including or not CL, indicating that CL effects were not important for the studied traits. For BW, the results indicated a partial confounding among the maternal additive genetic, environmental maternal and CL effects. The importance of maternal additive effects was greater for the BW traits (from 24.5% at least to 7.9% in the most comprehensive models) than for FW and FD. The relative importance of direct additive effects was also greater for BW (from 24.5 to 37,1%, for the different models), followed by FW (from 19.5 to 24.6%) and for FD (from16.3 to 21.0%). The heritability estimates indicated that the successful selection could be obtained for body weight, fleece weight ad fiber wool diameter of sheep Merino breed