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This study was designed to evaluate the effectiveness of a luteinizing hormone releasing hormone (LHRH) fusion protein immunization on reproductive traits in ram lambs including the changes in histology and ultrasonographic appearance of testis. Thirty native ram lambs at 19 weeks of age were divided into control (C, n = 10), immunization (I, n = 10) and castration (E, n = 10) groups. Animals in immunization group were immunized against LHRH using ovalbumin-LHRH-7 (OL) protein generated by recombinant DNA technology as a primary and a booster injection at 19 and 23 weeks of age respectively. Animals were bled via jugular venepuncture at 2-week intervals to determine LHRH antibody and testosterone concentrations. Bi-weekly ultrasonographic examination of the testes was performed to determine the changes in ultrasonographic appearance as the age increased. Biopsied testicular tissues taken at 19, 29 and 41 weeks age were also evaluated. At 41 weeks of age, animals were slaughtered. Semen and epididymis were evaluated for the presence of sperm cells. Testicular development and sperm production were suppressed in the immunized animals. Semineferous tubule diameters decreased, basal membrane of the tubule was thickened and hyalinized in immunized ram lambs. While testes of control animals gained their normal ultrasonographic appearance as the age increased, immunized animals had uniform hypoechogenic testicular structure as observed at 19 weeks of age until slaughter. Simultaneous histological and ultrasonographic evaluations indicated that the changes in testicular histology could partly be monitored via ultrasonographic imaging. Nevertheless, it is difficult to claim that ultrasonographic image reflects the exact changes in such instances. In conclusion, these results indicate that recombinant OL fusion protein is effective in immunocastration in ram lambs and has a potential to be used as an alternative to physical castration. Further research studies should be conducted to help assess reproductive status of testes from ultrasound images.

Abstract. This study was carried out on 60 Norduz ewes to determine the effect of ewe body condition at lambing on growth of lambs and colostral specific gravity. Body condition score (BCS), ranging from 2.5 to 3.5, had no effect on lamb live weight at birth, 30, 60, 90 and 120 days of age (P > 0.05). The average colostral specific gravity determined as 1.049 was not affected by body condition of ewes. A moderate positive correlation (r = 0.436) was observed between condition score and live weight of ewes (P < 0.001). The results of this study suggest that BCS is not a reliable estimator of live weight for Norduz ewes.

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The study was conducted to compare the individual growth curves models and to detect individual differences in the growth rate by a performing multilevel analysis. The data set used for this purpose consisted of live weight records of 52 crossbred lambs from birth to 182 days of age. There were 670 observations in level-1 units which were the repeated measurements over time, and there were 52 observations in level-2 units which were lambs. In the study, parameter estimation of timeindependent covariate factors, such as gender, birth type and birth weight, was performed by using five different models within the framework of multilevel modeling. LRT, AIC and BIC were used for the selection of the best model. The "Conditional Quadratic Growth Model-B" provided the best fit to the data set. The multilevel analysis indicated that linear and quadratic growth in lambs was significant. According to the results of the study, individual growth curves can be investigated using multilevel modeling in animal studies which is an important parameter of the individual growth rate.