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Bone problems are highly prevalent in laying hens. These problems affect the welfare, production and economic losses. Bone development begins in the embryonic period, and if the skeletal system develops well at that time, the subsequent production period can be affected positively. The present experiment aimed to investigate the effect of genotype on biomechanical parameters and composition of bone in the laying hen embryos. For this purpose, 360 fertilized eggs were obtained from two brown (Atak-S and Brown Nick) and two white (Atabey and Nick) layer breeders and incubated. Metatarsus, tibia and femur properties were examined on the embryonic d 19 and 21. Results showed that genotype played an important role in determining the biomechanical properties and mineral composition of the metatarsus, tibia and femur in the embryonic period. Examined bone characteristics improved with embryonic age. The least mineralization was observed in the metatarsus bone. In conclusion, bone properties were influenced from the genotype. However these differences were not related with laying hens being white or brown. The effect of the interaction between genotype and embryonic age on the bone properties should be considered., Yumurtacı tavuklarda kemik sorunları oldukça yaygındır. Bu sorunlar refahı, üretimi ve ekonomik kayıpları etkiler. Kemik gelişimi embriyonik dönemde başladığından bu dönemde iskelet sistemi iyi gelişirse, sonraki üretim periyodu olumlu yönde etkilenebilir. Bu çalışmada genotipin yumurtacı tavuk embriyolarında kemiğin biyomekanik özellikleri ve bileşimine etkisini incelemek amaçlanmıştır. Bu amaçla iki kahverengi (Atak-S ve Kahverengi Nick) ve iki beyaz (Atabey ve Nick) yumurtacı damızlıklardan elde edilen 360 adet döllü yumurta toplanmış ve inkübe edilmiştir. Embiyonik dönemin 19 ve 21. günlerinde metatarsus, tibia ve femur özellikleri incelenmiştir. Sonuçlar, embriyonik dönemde genotipin metatarsus, tibia ve femurun biyomekanik özellikleri ve mineral bileşiminde önemli bir rol oynadığını göstermiştir. Embriyonik yaşın artmasıyla incelenen kemik özellikleri iyileşmiştir. En az minerilizasyon metatarsus kemiğinde gözlenmiştir. Sonuç olarak, kemik özellikleri genotipten etkilenmiştir. Fakat bu farklılıklar beyaz veya kahverengi yumurtacı tavuk olmasıyla ilişkili değildir. Genotip ve embriyonik yaş arasındaki etkileşimin kemik özellikleri üzerindeki etkisi dikkate alınmalıdır.

The aim of this study was to evaluate some pelleting characteristics of beef cattle concentrate with added sepiolite and potassium humate alone or combined. For this purpose, one control group (basal concentrate) with no additive and five treatment groups with 1% sepiolite (S), 0.25% potassium humate (H-25), 0.50% potassium humate (H-50), 1% sepiolite + 0.25% potassium humate (SH-25) and 1% sepiolite + 0.50% potassium humate (SH-50) added as top-dressed into mixer were used. For each experimental group, a total of 36 tons of pellet concentrates were produced in six batches with 6 tons per batch. The basal pelleted concentrate included 90.29% dry matter, 14.51% crude protein, 11.76% crude fibre and 3.14% ether extract. Results showed that adding sepiolite up to 1% in beef cattle concentrate as top-dressed in mixer reduced moisture losses and improved the durability of pelleted feed. Sepiolite addition also lowered pellet water activity during storage. Adding potassium humate alone up to 0.50% was not enough to improve the pellet quality in terms of durability or water activity. Potassium humate supplementation alone or with sepiolite presented with lower moisture losses than control, and it was more evident during storage. In conclusion, the use of sepiolite in beef cattle concentrates as pellet binder seemed to be providing more durable feed pellets with lower water activity. Promising results were obtained from both the supplements in limiting the moisture losses post- pelleting and storage. Regarding the role of potassium humate as pellet binder in animal feed industry further research is needed.