In this research, in order to predict genetic parameters and genetic and environmental trends of birth weight and weaning weight of Najdi calves, 1249 records collected during the period of 1989 - 2004 in Najdi cattle Research Station of Khuzestan were used. Variance components, genetic parameters and predicted breeding values were estimated for traits, using animal model with direct and maternal additive genetic effects as the best model and restricted maximum likelihood method based on a derivative-free algorithm. Phenotypic, genetic and environmental trends were calculated as the regression of average phenotypic values, predicted breeding values and environmental values on year of calf birth, respectively. Direct and maternal heritability for birth weight and weaning weight were estimated 0.37±0.11, 0.08±0.04, 0.13±0.06 and 0.1±0.06, respectively. Phenotypic trends of traits were 0.07±0.05 kg/year and 0.21±0.3 kg/year for birth weight and weaning weight, direct additive genetic trends for these traits were 0.06±0.01 kg/year and 0.13±0.04 kg/year, and maternal additive genetic trends for these traits were 0.03±0.005 kg/year and 0.13±0.01 kg/year, respectively. Environmental trends were estimated as 0.02±0.06 kg/ year and 0.04±0.3 kg/year, respectively.

To study the effect of non-genetic factors on survival of Karakul lambs from birth to weaning age 6, 426 records collected from year 1992 through 2009 were used. Traits under study were cumulative survival from birth to 14, 30, 60 and 90 days of age. For each trait a linear model fitted which included the factors of lambs' year and month of birth, type of birth, sex, age of dam and birth weight (as linear and quadratic covariates). The GLM procedure of SAS software was applied. All the factors except for age of dam had significant effects (P<0.001) on traits. Mortality to weaning age in total, single and twins were 8%, 5.87% and 17.79% respectively. Hazard ratio of death from birth to 30d of age had increasing trend and after that till weaning showed decreasing one. In males and twins hazard of death was higher compared to females and single lambs.Average birth weight in singles and twins were 5.32 (0.67) and 4.25 (0.65) kg respectively. Optimum birth weight in which survival would be maximum in 14, 30, 60 and 90 days of age in singles and twins were 5.78, 4.68; 5.88, 4.86; 5.93, 5.03 and 5, 5.93 kg respectively. Optimum birth weight in which survival would be maximum in 14, 30, 60 and 90 days of age in male and female lambs were 5.9, 5.4; 6.1, 5.6; 6.4, 5.6 and 5.9, 5 kg respectively. It can be suggested that in order to develop the survival of Karakul lambs we select lambs on the basis of the optimal birth weight instead of the higher one.

BACKGROUND: Flushing program can improve performance in sheep industry.OBGECTIVES: The aim of this study was evaluation the effects of using supplemental fat in Lori-Bakhtiari ewes flushing diet on their lambs' weaned weight.METHODS: Three hundred healthy and non-pregnant Lori-Bakhtiari ewes were selected and randomly allotted to three nutritional groups (n=100) as: basal diet (control or C treatment), basal diet with 250 grams barley grain(B treatment) and basal diet with 144.5 grams barley grain + 50 grams supplemental fat(BF treatment). Ewes received dietary supplement from day 14 before up to day 21 after ram introduction. Ewes' weight and body condition score before mating, ewes' weight at lambing, the number, sex, weight and type of lambs born, lambing date of ewes, lambs weaning weight and number of lambs weaned were recorded.RESULTS: Mean of ewes' weight at lambing in the BF group was higher than other groups (P<0.05).However, average lambs birth weight was numerically higher in BF group but, its difference with other groups was not statistically significant. Total birth weight of lambs per ewe exposed to mating was differ (P<0.05) and was highest in the group BF and lowest in control group. Similarly, total weaned lambs weight was highest in the group BF and lowest in the control group (P<0.01), however, the differences between groups BF and B, and B and control were not statistically significant.CONCLUSIONS: The use of supplemental fat with barley grain in Lori-Bakhtiari ewes flushing diet can be improved weight of weaned lambs.

Objective: Estimation of genetic parameters for Kleiber ratio (KR) and genetic trends for pre-weaning weights of Arabi sheep has not been previously conducted.Methods: Data and pedigree information were collected at the Khuzestan Ramin Agricultural and Natural Resources University, Animal Science Research Station, located in southwest Iran, from 2001 to 2008. (Co)variance components and corresponding genetic parameters were estimated using the restricted maximum likelihood procedure by excluding or including maternal genetic or maternal permanent environmental effects. Six animal models were fitted to optimise the model KR from birth to weaning, which is defined as the ratio of growth rate and metabolic rate and can be utilized as an indirect selection for feed conversion. Moreover, three-trait analyses were performed using the most appropriate models obtained in single-trait analyses on the basis of Akaike’s information criterion.Results: Direct heritability (h2d) estimate of 0.11 was obtained and maternal permanent environmental effects (pe2) contributed 10% of the total phenotypic variation for KR. Genetic trends for weight at birth and weaning were obtained by regression of average breeding values, on birth year. Direct genetic trends were positive and significant (p<0.05) for weight at birth and weaning (6 and 24 g per year, respectively). Genetic correlations among traits ranged from -0.52 to 0.89 and phenotypic correlations from -0.21 to 0. 0.71. Results showed the importance of inclusion of maternal permanent environmental effects in designing appropriate breeding programs to obtain accurate estimates of genetic parameters, and it is sounded that KR is a recommended option in selection program.

Lamb survival is one of the major factors affecting overall sheep productivity. Lamb survival affected by environmental effect such as management, birth-type, year, season of birth, dam-age, maternal behavior, genotype of parents, and birth-weight. The data comprised 9989 records were collected from 1989 to 2009 in Iranian Baluchi sheep at Abbasabad sheep breeding station. Four binary traits created, value 0 was assigned for lambs dead and 1 for lambs alive at certain ages. Cumulative survival to day 10, 30, 60 and 90 (weaning) was calculated. Birth-weight, litter-size, birth-type, dam-age and birth-year considered in analysis. Statistical analyses of cumulative lamb survival at 10, 30, 60 and 90 days after birth analyzed by application of logistic model with binary response variable. Analysis of variance for cumulative survival each trait separately were analyzed using SAS with a linear model. The fixed effects of the model included dam-age, birth-year, birth-type, herd and sex. From 9989 lambs born at Abbasabad station over the period 1989-2009, There were 5147 (51.5%) lambs born as male and 4847 (48.5%) female which that 5583 (56%) lambs as singles 4239 (42%) as twins and 167 (2%) as triplet. Among the singles, 79 (1.5%) were dead at 10days after birth, 229 (4.1%), 373 (6.68%), 435 (7.8%) died at 30, 60 and 90 days after birth respectively. The results indicated survival of male lambs less than female at from birth to weaning, single and twin born lambs were more survival than triplet at each age. Lamb born from ewes 2 years old or in first parity had lowest survival compared with other parities. The least survival occurred in first parity as result of lack of maternal experiences of ewes at that stage. Average birth weight all lambs was 4.28 ± 0.7 Kg. male lambs had heavier birth weight than female lambs (4.4±0.7 vs.4.1±0.6) also single born lambs (4.6±0.6) heavier than twin or triplet born lambs 3.8±0.6, 3.3±0.6 respectively. Linear and quadratic of birth-weight had significant effect on survival at 10, 30, 60 and 90days after birth. There was a curvilinear relationship between birth-weight and survival from birth to weaning. Survival for during birth to weaning maximized at 5 Kg although average birth-weight in this study was 4.3 Kg. Optimum birth-weight for survival of single, twin and triplet born lambs were 7, 5 and 4.3 Kg with (0.93, 0.93 and 0.92 %) survival compared average birth-weight at single, twin and triplet (4.6, 3.8 and 3.3 Kg) with (0.92, 0.92 and 0.91 %) survival. Female lambs had greater survival rate than male lambs at the same weight (1 to 2 %) Survival was maximized at 7 Kg birth weight for female (94 vs.91.5% at average birth-weight) and male at 5 Kg which was only slightly heavier than average birth weight of 4.4 Kg.

A selection program is being implemented to improve meat production in Makooei sheep. Increasing litter size per ewe is the main objective, but possible repercussions on weight traits of lambs should be considered. The aim of this study was to estimate heritability along with genetic and phenotypic correlations between ewe's reproductive vs. weight traits in Makooei ewes. Data were comprised of 5,364 records of body weight of lambs from 289 sires and 1,726 dams, plus 3,418 records of reproductive traits from 1,429 ewes collected from 1996 to 2009 from a Makooei flock at Makoo Station in West-Azerbaijan Province. The ewe reproductive traits investigated were Conception Rate (CR), Litter Size at Birth (LSB), Litter Size at Weaning (LSW), Litter Weight at Birth (LWB) and Litter Weight at Weaning (LWW). The lamb traits investigated were Weights at Birth (BW) and at Weaning (WW). Genetic parameters were estimated through REML procedure using ASReml program. The estimates of direct heritability for lamb body weights were 0.15±0.04 at birth and 0.16±0.03 at weaning. The estimates of heritability for reproductive traits varied from 0.05±0.02 for CR to 0.17±0.03 for LWB. Additive genetic correlations between BW and ewe's reproductive traits varied from small to moderate, ranging between –0.14 and 0.22. Additive genetic correlations between WW and ewe reproduction traits varied from moderate to high, positively ranging between 0.21 and 0.67. In conclusion, WW could be considered as a selection criterion in indirectly improving the ewe's reproductive traits in Makooei sheep.

This study aimed to estimate the genetic parameters of body weight traits in Markhoz goats, using B-spline random regression models. The data used in this study included 19549 records collected during 29 years (1992-2021) in Markhoz goat Breeding Research Station, located in Sanandaj, Iran. The model used to analyze data included fixed effects (year of birth, sex, type of birth and age of dam) and random effects including direct additive genetic, maternal additive genetic, permanent environmental and maternal permanent environmental assuming homogeneous and heterogeneous residual variance during the time. Akaike (BIC) and Bayesian (BIC) information criteria were used to compare the models and bspq.4.4.4.4 was selected as the best model. The direct heritability values for birth, 3-month, 6-month, 9-month and 12-month weights were estimated to be 0.14, 0.16, 0.08, 0.28 and 0.26, respectively. Genetic correlation between body weights at birth and 3-month, birth and 6-month, birth and 9-month, birth and 12-month, 3-month and 6-month, 3-month and 9-month, 3-month and 12-month, 6-months and 9-month and 9-month and 12-month were 0.22, 0.38, 0.21, 0.56, -0.26, 0.30, 0.62, 0.86 and 0.77, respectively. The highest phenotypic correlation was between the weight of 9-month and 12-month (0.82) and the lowest correlation was between birth weight and 3-month and 6-month (0.12). The results showed that the 9-month weight is a good criterion for selection in Markhoz goats.

In this study, chemical compositions of black seed meals samples were determined. 18 male weaning Zandi lambs with an average body weight of 23.5 ±1.5 kg were used in a completely randomized design in three groups of six in individual pens. Experimental treatments were: 1) control (basal diet with 12% soybean meal and without black seed meal), 2) diet containing 6% soybean meal and 9% black seed meal and 3) diet containing 18% black seed meal and without soybean meal. The concentration of dry matter, crude protein, crude fat, NDF, ADF, ADIN, and crude ash of black seed meal samples were 97.53±0.58, 31.26±0.99, 15.16 ± 0.61, 25.95 ± 1.34, 14.2±0.80, 0.69±0.04 and 5.07 ± 0.24, respectively. Replacement of soybean meal with black seed meal in the diet of experimental lambs had no effect on final body weight, daily weight gain, feed conversion ratio, dry matter intake, dressing percentage, tail and total body fat deposition. Albumin and total protein were higher for lambs fed by diet containing 18 % black seed meal compared to other treatments (P <0.05). However, the concentration of blood triglyceride, cholesterol and urea nitrogen were not differed between experimental groups. The digestibility of dry matter, organic matter, crude fat and protein were not affect by feeding of experimental diets. It seems that black seed meal can be used in the diet of fattening lambs up to 18% without adverse effect on performance and nutrients digestibility of growing lambs.