This study reports on the phenotypic and genetic (co)variance components for reproductive traits in Zandi sheep, using between 1,859 and 2,588 records obtained from 577 ewes. The data were collected from the Khojir Breeding Station of Zandi sheep in Tehran, Iran from 1994 to 2008. The basic traits were litter size at birth (LSB), litter size at weaning (LSW), litter mean weight per lamb born (LMWLB), and litter mean weight per lamb weaned (LMWLW), and the composite traits were total litter weight at birth (TLWB) and total litter weight at weaning (TLWW). Genetic analyses were carried out using the restricted maximum likelihood method that was explored by fitting the additive direct genetic effects and permanent environmental effects of the ewes as random effects and the ewe age at lambing and lambing year as fixed effects for all of the investigated traits. Akaike's information criterion was used to choose the most appropriate model. LSB, LSW, LMWLB, LMWLW, TLWB, and TLWW direct heritability estimates were 0.07, 0.05, 0.12, 0.10, 0.08, and 0.14, respectively. The estimated fractions of variance due to the permanent environmental effects of the ewe ranged from 0.03 for LMWLB to 0.08 for LMWLW and TLWW. Corresponding repeatability estimates ranged from 0.10 for LSW to 0.22 for TLWW. Direct genetic correlations varied from -0.61 for LSB-LMWLB to 0.88 for LSB-LSW and LSB-TLWB. Results indicate that genetic change depends not only on the heritability of traits, but also on the observed phenotypic variation; therefore, improvement of non-genetic factors should be included in the breeding programs.

Two experiments were conducted to determine the influence of dietary fibres on small intestine histomorphology and lipid metabolism in broilers from 1 to 21 day of age. In experiment 1, diets containing insoluble [cellulose (CEL); 2% and 4%] or soluble [carboxymethyl cellulose (CMC); 2% and 4%] fibre were fed to broilers from day 1 to 21 post-hatch and ileal tissue was collected at day 21 of age for histological evaluation. In experiment 2, broilers diet was supplemented with 0%, 1% or 2% insoluble fibre (Arbocel) during day 7 to 21 post-hatch and plasma and liver lipid metabolism were evaluated at day 21. In experiment 1, inclusion of CMC reduced body weight gain (BWG) and feed intake (FI) and increased feed conversion ratio (FCR) compared with others. Intestinal histomorphology was unaffected by CEL, but CMC led to an increase in crypt depth (CD) and serosa thickness and a decrease in villus height (VH), villus width (VW), VH:CD ratio and villus surface area (VSA), rather than control and CEL groups. Treatment did not affect goblet cell type. Moreover, the CMC-fed birds had greater total goblet cell count (GCC) as compared with others. In experiment 2, fibre inclusion was associated with increases in BWG from 7 to 14 day of age and an improvement in FCR, whereas FI was not influenced by treatments. Inclusion of fibre in the diet decreased the weight of the abdominal fat and cholesterol concentrations of liver and plasma. No significant effects on fatty acid composition of liver lipid were observed by fibre supplementation. These findings suggest dietary fibre affects performance, intestinal histomorphology and lipid metabolism in young chicks, which may directly affect poultry feeding strategies.

ABSTRACT. The effect of wheat-based diet (WBD), supplemented with xylanase and surplus vitamin A, on performance, nutrient digestibility, intestinal morphology and digesta viscosity of broiler chickens was investigated. Based on a completely randomized design, 240-day-old chickens were randomly divided into six experimental diets and four replications with 10 chickens each. Experimental diets consisted of corn-based diet (CBD) (T1), WBD with routine amounts of vitamin A (9000 IU kg xylanase (T6). For Feed Conversion Rate (FCR) between day 1 and 21 and between day 21 and 42 WBD supplemented with vitamin A and enzyme was less than CBD (p < 0.05). Also, supplementation of surplus vitamin A singly, and vitamin A and enzyme improved digestibility of crude protein (CPD) and crude fat (CFD) than WBD with routine amounts of vitamin A (p < 0.05). The villus (duodenum, jejunum and ileum) was longer (p < 0.05) in broilers fed on diet supplemented with vitamin A and enzyme than those with CBD. It may be concluded that enzyme and vitamin A supplementation to WBD may improve mentioned parameters.Keywords: digestibility, enzyme, morphology, viscosity, vitamin A, wheat.Os efeitos de xilanase e vitamina A em dieta baseada no trigo (DBT) sobre o desempenho, digestibilidade de nutrientes, morfologia do intestine delgado e viscosidade da digesta em frangos de corte RESUMO. Investigou-se o efeito de dieta baseada no trigo (DBT) e suplementada com xilanase e vitamina A sobre o desempenho, digestibilidade dos nutrientes, morfologia intestinal e viscosidade digesta de frangos de corte. Baseado num esquema aleatório, frangos de 240 dias foram divididos em grupos de seis dietas experimentais, com quatro repetições, com 10 frangos cada. As dietas foram: T1 = dieta baseada em trigo; T2 com DBT com vitamina A (9000 IU kg xylanase. Para a Taxa de Conversão de Dieta entre dia 1 e 21 e entre dia 21 e 42 DBT suplementada com vitamina A e enzima foi menor do que DBM (p < 0,05). Suplementacão sozinha de vitamina A e vitamina A + enzima melhoru a digestibilidade de proteina bruta (DPB) e gordura bruta (DGB) do que DBT com a quantidade rotineira de vitamina A (p < 0,05). As vilosidades (duodeno, jejuno e íleo) eram mais compridas (p < 0,05) em frangos de corte alimentados com dieta suplementada com vitamina A e enzima do que os frangos alimentados com DBM. Conclui-se que a suplementação de DBT pela enzima e vitamina A poderá melhorar os parâmetros acima.

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Neural networks are capable of modelling any complex function and can be used in poultry production. Dietary crude fibre (CF) and exogenous enzymes (exEn) extensively affected abdominal fat (AF) of broilers. Current methods to study AF and its correlation with dietary CF levels and exEn supplements are costly, laborious and time-consuming. The purpose of this study was to develop an artificial neural network-genetic algorithm (ANN-GA) to model data on the response of broiler chickens (AF) to CF and exEn from 0 to 42 days of age. A data set containing eight treatments was divided to the train, validation, and test data set of the ANN models. The information about feeding eight diets at two periods [starter (0-21 days of age) and grower (22-42 days of age)] were used to estimate AF of broilers by ANN-GA. A multilayer feed-forward neural network with different structures was developed using matlab software, and optimal values for the ANN weights were obtained using the genetic algorithm (GA). Crude fibre, and exEn were used as input variables and AF of broilers was output variable. The best model of ANN-GA was determined based on the train root mean square error (RMSE). The best selected ANN-GA showed desirable results, RMSE, 0.1286% and R(2) coefficient, 0.876 for test data.