Volume 11, Issue 27 (4-2020)                   rap 2020, 11(27): 27-34 | Back to browse issues page

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khorsand H, ghalamkari H R, sanei A, rezaei R, akbari A. The Effect of Reducing Ration Protein Level Using Commercial Premixes on the Performance and Blood Parameters of Holstein Dairy Cows. rap. 2020; 11 (27) :27-34
URL: http://rap.sanru.ac.ir/article-1-1016-en.html
Sepahan Daneh Parsian
Abstract:   (268 Views)
   The aim of this experiment was to evaluate the effects of concentrate premixes containing of by-pass proteins (BP) in balanced low protein diets for essential amino acids on performance, blood metabolites and nitrogen efficiency of lactation Holstein dairy cows. Twenty-four multiparous Holstein cows (in 3rd parity and DIM 80±10) randomly were divided to three experimental rations including, 1) control ration with 17.5% CP based on NRC 2001 recommendations, 2) Low protein ration containing concentrate premix with 16.5% CP and 3) Low protein ration containing concentrate premix with 15.5% CP. The ratio of the rumen undegradable protein (RUP) to rumen degradable protein (RDP) in experimental diets was 37:63 and the ratio lysine to methionine was adjusted by concentrate premix up to 3:1 and 2.8:1 in the diet 16.5% and 15.5% CP, respectively. The results showed that the dry matter intake (DMI) increased linearly with a reduction of CP in the diets (P=0.048). The highest 3.5% fat corrected milk yield (FCM) and energy corrected milk (ECM) was recorded for 16.5% CP diet that showed a significant difference than other groups (P=0.038). Milk protein yield and milk nitrogen efficiency (MNE) showed significantl difference between control and 16% CP diets (P=0.05 and P=0.03, respectively). This study showed that decreased in CP levels compared to recommended NRC values (2001), and providing an optimal ratio of limiting amino acids can increase nitrogen yield while maintaining production.
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Type of Study: Applicable | Subject: تغذیه نشخوارکنندگان
Received: 2019/05/14 | Revised: 2020/05/12 | Accepted: 2019/11/9 | Published: 2020/05/12

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