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Classification of West Anatolian Cities for sheep production [Koyunculuk Açi{dotless}si{dotless}ndan Bati{dotless} Anadolu İllerinin Si{dotless}ni{dotless}flandi{dotless}ri{dotless}lmasi{dotless}]
(2011) GevrekçI Y.; Ataç F.E.; Takma C.; Akbaş Y.; Taşkin T.
In this study sheep production structures of 11 West Anatolian cities (Afyonkarahisar, Aydi{dotless}n, Bali{dotless}kesir, Bursa Çanakkale, Denizli, İzmir, Kütahya, Manisa, Mugla and Uşak) have been compared and classified. Data were obtained from Turkish Statistical Institute including numbers of sheep and milking sheep, sheep milk production, number of slaughtered sheep, sheep meat production, number of sheep shorn, wool production during 2003-2008 years. Multidimensional Scaling and Cluster Analyses were used for classifying the cities for sheep production. Results from MDS and cluster analyzes show that four city groups for sheep production were available such as Afyonkarahisar - Bali{dotless}kesir; İzmir - Manisa; Bursa - Çanakkale - Denizli - Kütahya - Uşak, and Aydi{dotless}n - Mugla.
Comparison of different covariance structure used for experimental design with repeated measurement
(2010) Eyduran E.; Akbaş Y.
This study was conducted to compare performance of univariate and multivariate approaches used for analyzing experiments with repeated measurement and determine the best covariance structure for the data studied. In this study, univariate ANOVA, Geisser-Greenhouse Epsilon and Huynth-Feldt Epsilon were used as univariate approaches while profile analysis, Containment, Satterthwaite and Kenward-Roger approaches in general linear mixed model were applied as multivariate approaches. Annual amounts of wheat production from 65 provinces in seven geographical regions of Turkey from 1982 to 1999 were used as research material. A total of 1170 production values were obtained. In General Linear Model, nine various covariance structures (CS, CSH, UN, HF, AR (1), ARH (1), ANTE (1), TOEP and TOEPH) were applied. AIC and AICC criteria were used to determine the most appropriate covariance pattern for fitting data. In the study, "spherity assumption" for amounts of wheat production of provinces was violated. Application of Containment, Satterthwaite and Kenward-Roger approaches in general linear model and determination of covariance structure with the best fit were provided. According to AIC and AICC fitting criteria, it was determined that CS covariance structure gave the best fit to data set. As a result, covariance structure is compound symmetry (CS) in standard univariate ANOVA, and unstructured (UN) covariance structure in MANOVA. However, determination of the most appropriate covariance structure for data set is possible in multivariate general linear model. Containment, Satterthwaite, and Kenward-Roger approaches gave similar results since total sample size was sufficient. On the other hand, usage of Containment, Satterthwaite and Kenward-Roger approaches in analyzing experiments with repeated measurement were suggested to allow selection of the most suitable covariance structure for data set.
Comparison of different models in genetic analysis of dystocia [Buzagi{dotless}lama Güçlügünün Genetik Analizinde Farkli{dotless} Modellerin Karş i{dotless}laşti{dotless}ri{dotless}lmasi{dotless}]
(2011) Gevrekçi Y.; Akbaş Y.; Kizilkaya K.
The aim of this study was to compare threshold sire model (TS), threshold sire-maternal grandsire model (TS-MGS) and linear sire-maternal grandsire model (L) for genetic analysis of dystocia. Threshold models were based on Bayesian approach. In the study, a total of 19439 dystocia records from Holsteins in USA were used. The effects of calving year-season, sex of calf, parity of dam, sire of calf and herd effects were included in all models and also maternal grandsire effect of calf was included in only sire-maternal grandsire models. Variance-covariance estimates were greater in threshold models than in linear model. Estimates of heritability (±SE) of dystocia based on direct genetic effects (h2D) and maternal genetic effects (h2M) were 0.18±0.004 and 0.14±0.004 from TS-MGS and 0.12±0.003 and 0.09±0.003 from L, respectively. Heritability estimates based on direct genetic effects from TS was 0.20±0.009. Genetic correlation between direct and maternal genetic effect were -0.087±0.006 from the TS-MGS and -0.253±0.010 from L. It was concluded that the threshold models were better than the linear model in the analysis of dystocia. The higher heritability estimates on the underlying scale from threshold models should allow greater genetic improvement than those using linear model estimations.
Comparison of fitting performance of random regression models to test day milk yields in Holstein Friesians [Kil Keçisi (Capra hircus) Sütlerinden Polimeraz Zincir Reaksiyonu (PZR) ile Brucella melitensis Saptanmasi]
(2009) Takma C.; Akbaş Y.
In this study, random regression models with Ali-Schaeffer functions, Wilmink functions and orthogonal Legendre polynomials were compared for fitting performance to test day milk yields. Legendre polynomials with orders from two to six for additive genetic and permanent environmental effects were fitted under homogeneous error variance assumption throughout lactation. The analyzes were applied to 5918 first lactation test day milk yields of 612 Holstein Friesian cows calving from 1987 to 1993 in Dalaman, Tahirova, Sarimsakli and Türkgeldi State Farms. To compare the models, residual variances, -2LogL value, Akaike's information criterion, Bayesian information criterion and eigenvalues for additive genetic and permanent environmental random regression (co)variance matrix were used. Among 27 models, the L(6,2), L(6,5) and L(6,6) were chosen as better models.
Comparison of Several Models to Fit the Growth Curves of Kivircik and Dagliç Male Lambs [Farkli Modellerin Kivircik ve Dagliç Erkek Kuzularinin Büyüme Egrilerine Uyumunun Karşilaştirilmasi]
(1999) Akbaş Y.; Taşkin T.; Demirören E.
This research was carried out to estimate the growth curves of Kivircik and Dagliç male lambs using monthly body weight data from birth to 420 days of age. Fifteen models were compared in terms of growth curve parameters and for the best fit to the data of Kivircik and Dagliç male lambs. Among the linear models simple linear model gave the best fit for Dagliç and quadratic model for Kivircik. However heterogenity was found in terms of regressions equations within each breed and between genotypes. These results say that common regression equation can not be used for all individual in a breed having different growth pattern, not only regression coeffiecient but also mean levels of dependent variable. Among the non-linear models Brody, Negative Exponential, Gompertz, Logistic and Bertalanffy gave quite good fit for the male lambs data. Brody had the highest coefficient of determination.
Defining the best covariance structure for sequential variation on live weights of anatolian merinos male lambs
(2010) Orhan H.; Eyduran E.; Akbaş Y.
In a repeated measures design with two factors, between-subjects and within-subjects, the most appropriate (univariate or multivariate) method and the best covariance structure explaining sequential variation in live weights of Anatolia Merinos lambs fed with different rations were estimated. In general linear mixed model, univariate ANOVA, Geisser-Greenhouse and Huynth-Feldt epsilon were used as univariate methods while profile analysis as well as mixed model methodology were applied as multivariate methods. The data were composed of twenty-four Anatolia Merinos male lambs with weaning age of 2-2.5 months randomly selected from Polatli State Farm and divided equally into four groups. Rations were mas hor pelletted using molasses, lignobond and aquacup binders. Live weights were measured at six times during experimental period (day 0, 14, 28, 42, 56 and 70). In general linear mixed model, nine covariance structures (CS, CSH, UN, HF, AR(1), ARH(1), ANTE(1), TOEP and TOEPH) were applied. AIC, AICC and SBC criteria were used to detect the best defining covariance structure for fitting data. The best covariance structure for the data set was found to be Unstructured (UN). In the case of violation of spherity assumption, using mixed model approach was advised according to AIC, AICC and SBC criteria. As a conclusion, in repeated measures design use of mixed model methodology was recommended to determine the best covariance structure for defining experimental data sets.
Determination of factors affecting 305-day milk production via path analysis on holstein friesians [Siyah alaca sığırlarda 305 günlük süt verimini etkileyen faktörlerin path (iz) analizi İle belirlenmesi]
(Veteriner Fakultesi Dergisi, 2015) Işçi Güneri Ö.; Takma Ç.; Akbaş Y.
A quantitative trait was affected directly or indirectly by several factors due to relationships among them. It is necessary to identified direct and indirect effects of a factor to reveal all relationships in a detailed way. In this study, total of 11647 305-day milk yield records from the 7 parities of 5047 Holstein Friesian cows were statistically evaluated for determining direct and indirect effects of parity (X1), year of calving (X2) and lactation length (X3) on 305-day milk production (Y) via path analysis. Correlations among 305 day milk yield, parity, year of calving and lactation length were calculated 0.17, 0.43, 0.54 respectively and found statistically significant ((P<0.01). The direct effects of the parity, year of calving and lactation length on 305-day milk production were found PY1=0.12, P21=0.10, P31=0.46 respectively and statistically significant (P<0.01). The indirect U effect of parity via year of calving and S effect via lactation length on 305 day milk yield were found 0.01 and 0.04, respectively. The indirect U effect of year of calving via lactation length and S effect via parity on 305 day milk yield were found 0.31 and 0.02, respectively. Moreover, the indirect U effect of lactation length via year of calving and S effect via parity were found 0.07 and 0.01, respectively and lower. © 2015, KAFKAS UNIVERSITY. All rights reserved.
Effect of different residual variances on genetic parameters of test day milk yields [Denetim günü süt veriminin genetik parametre tahminine farklı hata varyanslarının etkisi]
(Veteriner Fakultesi Dergisi, 2015) Takma Ç.; Akbaş Y.
Heterogeneous residual variance effects on genetic parameters were examined for test day milk yields of Turkish Holsteins. A third order random regression models including the fixed, random additive genetic and permanent environmental effects were used. One of these models, RV10, residual variances is assumed to be different for each test day milk yields. The RV1 model has constant residual variance for each test day. Sequential (RV2 to RV9) and non-sequential (NRV2 to NRV9) groups of residual variances were also described in the models in order to compare estimates of variance components. The univariate analysis of milk yields for each test days was performed to define variance groups. The predicted residual variances ranged from 5.62 to 11.75 and from 5.61to 11.71 for RV and NRV models, respectively. Estimates of additive genetic variances changed between 0.55-6.76 for RV and 0.08-2.46 for NRV models. Permanent environmental variances were found between 2.36 and 18.60 for RV and 6.92 to 18.85 for NRV models. Heritability estimates varied from 0.02 to 0.43 for RV and 0.01 to 0.13 for NRV models. As a result, more accurate genetic parameter estimates are achieved by controlling the residual variances. RV10 model should be preferred to define details of the milk yield residual variances for each test day. However, RV5 model has been determined that an alternative model as compared with RV10. © 2015, Veteriner Fakultesi Dergisi. All rights reserved.
Effects of cage density on the performance of laying hens during high summer temperatures [Yüksek yaz sicakliklarinda kafes yerleşim sikliginin yumurta tavuklarinin performansi üzerine etkileri]
(2002) Altan A.; Altan Ö.; Özkan S.; Özkan K.; Akbaş Y.; Ayhan V.
This study was conducted to determine the effects of different cage densities on laying performance of white and brown hybrid layers during high summer temperatures. White layers, 68 weeks of age, were housed at a density of 3, 4 or 5 hens/cage (respectively 640, 480 and 384 cm2/hen); brown layers were housed at 3 or 4 hens/cage (respectively 640 and 480 cm2/hen). The results indicated that housing at 3 or 4 hens/cage did not affect egg production or egg quality significantly. Increasing the cage density to 5 hens/cage in white layers decreased egg production and Haugh Units. However, it was observed that shell quality and egg weight were not affected significantly by higher cage density.
Effects of selection for high body weight and age of hen on egg characteristics in Japanese quail (coturnix coturnix japonica) [Japon bildircinlarinda (coturnix coturnix japonica) canli agirlik yönünde yapilan seleksiyonun ve yaşin yumurta özelliklerine etkileri]
(1998) Altan Ö.; Oguz I.; Akbaş Y.
The present study was conductud on quails (Coturnix coturnix japonica) to evaluate the effects of line and age of bird on egg characteristics. Total ninety Japanese quail from unselected (C) and selected (S) for high 4-week body weight for five generations were used. All birds were weighed individually at 10, 14 and 18-week of age and egg characteristics were obtained on all eggs collected during these weeks. The results showed that egg weight was increased by selection for high 4-week body weight and egg weight differences between the lines was due to increases in yolk and albumen weight of egg. However there were no difference in percentages of albumen, yolk and egg shell between S and C lines. Egg productions of two lines were similar. While increasing flock age. egg weight was increased, egg shell thickness was decreased, haugh unit and shape index were not changed. Consequently, composition of egg was changed by age of bird. In early stage of egg production yolk percentage was lower, albumen percentage was high in S line than C line, but later stage of production these differences between the lines were disappeared.
Effects of udder and teat morphology, parity and lactation stage on subclinical mastitis in holstein cows [Siyah alaca i·neklerde meme ve meme başi formu ile laktasyon sirasi ve laktasyon döneminin subklinik mastitis üzerine etkisi]
(2003) Uzmay C.; Kaya I.; Akbaş Y.; Kaya A.
The relationships of udder and teat morphology, parity, and lactation stage with subclinical mastitis were investigated in cows raised in herds registered with the Izmir Holstein Breeders Association. Data from 887 cows in 21 herds were used. The udder and teat morphology of the cows was scored. Detection of subclinical mastitis was performed by a hand-held device measuring the electrical conductivity of the milk. It was found that 55.9% of cows had trough-shaped udders, 25.9% had ball-shaped udders, 11.5% had rear-heavy udders, and 6.7% had pendulous udders. Teats were cylindrical in 73.3%, funnel-shaped in 18.8%, pear-shaped in 3.2%, and long and thick in 4.7% of cows. Teats were located squarely in 54.1% of cows, and rear teats were closer to each other compared with the front teats in 45.9%. In multivariate logistic regression analysis, udder and teat morphology, parity, and herd were found to affect significantly (P < 0.001) the probability of subclinical mastitis. The effects of teat placement and stage of lactation were not significant. Cows with trough-shaped udders had the lowest risk of subclinical mastitis, and cows with pendulous udders had the highest risk. When teat morphology was considered, the risk of subclinical mastitis was highest for cows with long and thick teats. The risk of subclinical mastitis for cows with funnel-shaped teats was found to be lower than for cows with cylindrical teats. The risk of subclinical mastitis was found to increase as parity rose.
Estimation of breeding values with heterogeneous residual variances by random regression models [Şansa Bağlı Regresyon Modelinde Heterojen Hata Varyansları ile Damızlık Değerinin Tahmin Edilmesi]
(Veteriner Fakultesi Dergisi, 2015) Takma Ç.; Akbaş Y.
In this study the third order random regression models (RV1 and RV10) including the fixed, random additive genetic and permanent environmental effects were used. In the RV1 model residual variance was constant and in the RV10 model all test day records were taken as different groups. The predicted error variance was found 6.83 in RV1 model and this variance was changed between 5.30 and 9.19 in RV10 model. Heritability values were estimated 0.12-0.53 for RV1 and 0.04-0.18 for RV10 models. Spearman rank and Kendall rank correlations between estimated breeding values of test day milk yields estimated from RV1 and RV10 models within cows (0.79, 0.61) were found almost same with within sires (0.82 and 0.63). Consequently, these correlations indicate that breeding values estimated from RV1 and RV10 models were highly correlated. Although the association between two set of breeding values estimated from RV1 and RV10 models were high, ranking of cows and sires by breeding values were different for two models. The shift in rank of first 100 cows was found 22% same and 78% different, also the shift in rank of first 50 sires was found 30% same and 70% different on RV1 and RV10 models breeding values rank list. Overall, the RV10 model was found better than RV1 model in estimation of breeding value. © 2016 Veteriner Fakultesi Dergisi. All rights reserved.
Genetic variability of residual feed consumption (RFC) and its relationships with some production traits and fear response in Japanese quail hens (Coturnic coturnix japonica)
(2004) Altan Ö.; Oguz I.; Akbaş Y.; Akşit M.
The present study was conducted to estimate genetic parameters of residual feed consumption (RFC) and some other feed consumption traits (feed intake, feed efficiency and feed conversion) and to investigate the phenotypic and genetic correlations between RFC and feed traits, egg production traits and fear response in Japanese quail (Coturnix coturnix japonica). Moderate to high heritabilities were estimated for RFC between 10-14 week of age, ranging from 0.12 to 0.52. Heritability estimates for RFC had a tendency to decrease with age. The phenotypic and genetic correlations between RFC and egg production traits were generally low. Rather high genetic correlations between RFC and duration of tonic immobility TI (0.37) and number of inductions (-0.33) were estimated. Genetic correlations between feed traits and tonic immobility responses imply that quail hens utilizing feed more efficiently and consuming less feed may be less fearful and less susceptible to stress. Based on the results of present study, it can be concluded that RFC can be used as a selection criteria to improve efficiency of feed utilization without significant negative changes in egg production and egg quality traits and with a decrease in susceptibility to stress.
The level of inbreeding and its effects on milk yield, age at first calving and calf mortality in Holstein cattle reared on the Agricultural Faculty farm of Ege University [Ege üniversitesi ziraat fakültesi çiftliginde yetiştirilen siyah alaca sigirlarda akrabali yetiştirme düzeyi ve bunun süt verimi, i·lkine buzagilama yaşi ve buzagi ölümleri üzerine etkileri]
(2003) Uzmay C.; Akbaş Y.
In this study, the inbreeding coefficient of 1535 Holstein calves born on the Agricultural Faculty farm of Ege University during the period 1980-2000 was calculated, and the change of inbreeding levels over the years was investigated. Furthermore, the effects of inbreeding on first lactation 305-day milk yield, age at first calving and calf mortality were examined. The mean inbreeding level of calves born in the investigated period was 1.89%. The level of inbreeding in the herd fluctuated from 0% to 4.37% according to the birth years of calves. Furthermore, over the last 3 years of the period (1998-2000) inbreeding steadily increased. Over the years, it was estimated that a linear relationship (R2 = 0.62) existed between the inbreeding level and the percentage of sires bred in the herd. Estimates of inbreeding depression per 1% increase in inbreeding were -16.9 kg for milk yield, and 2.8 days for age at first calving. These levels of depression, however, were not statistically significant. A significant relationship between inbreeding and calf mortality was found. While calf mortality for non-inbred calves was 8.9%, it was 17.8% for calves with an inbreeding level ? 12.5%.
Variance components and genetic parameter estimates using random regression models on test day milk yields of Holstein Friesians [Siyah Alacalarda Şansa Bagli{dotless} Regresyon Modelleri Kullani{dotless}larak Denetim Günü Süt Veriminin Varyans Bileşenleri ve Genetik Parametrelerinin Tahminlenmesi]
(2009) Takma C.; Akbaş Y.
Genetic parameters for test day milk yields of Holstein Friesian cows were estimated by random regression with Legendre polynomials. The analyzes were applied to 5918 first lactation test day milk yields of 612 Holstein Friesian cows calving from 1987 to 1993 in Dalaman, Tahirova, Sarimsakli and Türkgeldi State Farms. Estimated genetic variances for test day milk yields were larger at extremes of the lactation. Permanent environmental variances mostly decreased in middle part of the lactation. The heritability values for test day milk yields were from 0.26 to 0.57. The genetic correlations between test day milk yields (TD1-TD9) with the last test day milk yield (TD10) were changed from -0.10 to 0.96 and it was high between consecutive test day milk yields, but decreased when the intervals between the test days increased. In random regression models it can be concluded that higher order polynomials were recommended for a sufficient fit of the (co)variance structures over the lactation but a reduction of the orders can also be used for computational simplicity due to small numbers of parameters.
Variation in organic acids content during ripening of pickled white cheese
(American Dairy Science Association, 2002) Akalin A.S.; Gönç S.; Akbaş Y.
Nine organic acids (formic, pyruvic, lactic, acetic, orotic, citric, uric, propionic, and butyric) were analyzed during ripening of pickled White cheese for 12 mo by high-performance liquid chromatography with a reverse phase CIS (120x 5-mm) column and UV detector. The level of total organic acids showed an increase along the ripening period, but its composition varied during the process. Initially, lactic acid accounted for 95% of the total, after 9 and 12 mo of ripening, butyric acid constituted 20 and 27% of the total, respectively. Each organic acid presented a characteristic pattern of change during ripening. Discriminant analysis classified cheeses according to their age. Stepwise regression analysis allowed estimation of the ripening time of samples according to their organic acid levels.

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