%0 Journal Article %T The effects of dry period length on cow milk yield and milk components in commercial Holstein dairy herds %J Iranian Journal of animal Science %I پردیس کشاورزی و منابع طبیعی دانشگاه تهران %Z 2008-4773 %A Mirzaei-Alamouti, Hamidreza %A Shapourzadeh, Ali %A Akbari-Pabandi, Kamran %A Zahmatkesh, Davood %D 2017 %\ 02/19/2017 %V 47 %N 4 %P 599-608 %! The effects of dry period length on cow milk yield and milk components in commercial Holstein dairy herds %K dry period %K milk component %K milk yield %K protein percent %R 10.22059/ijas.2017.204921.653440 %X The aim of this study was investigating the effects of dry period length on milk production and milk component in commercial large dairy herds using 2143 cow records. The Cows were classified according to dry period length in ≤ 45, 45-51, 52-65, 66-76 and ≥ 75 days. Milk yield and contents were recorded during 6 to 12 months. Data were analyzed using the MIXED MODEL procedure of SAS. Results indicated that reduced dry period length to less than 45-day reduced milk production yield, and changes in body condition score and rate of retained placenta was increased. Milk fat content decreased none linearly with increasing dry period length and it was the least when length of dry period was 52-65 days. Dry period length cubically affected protein content of milk; protein content was decreased and then increased by increasing dry period length. Generally, the results showed that reduceing dry period length to less than 45 day had negative effects on health, milk yield and milk components. %U https://ijas.ut.ac.ir/article_61165_3bb2e380c7cb7ba891ea9a51e19d4acf.pdf