اثر نسبت هاي مختلف سيلاژ ذرت به يونجه خشك بر بازده توليدي و توليد مثلي گاوهاي شيري هلشتاين در اوايل و اواسط شيردهي در فصل تابستان

چكيده انگليسي :

72Effect of different ratios of alfalfa hay to corn silage on production andreproductive efficiency in early and mid lactation Holstein dairy cows in summer Mohammad Arabsorkhi Telkabadi Arabsorkhim@gmail com eptember 22 2014 S Department of Animal ScienceCollege of Agriculture Isfahan University of Technology Isfahan 84156 83111 IranDegree M Sc Language PersianSupervisor M Khorvash khorvash@cc iut ac irAbstractIn the most dairy farms in Iran forage portion is consisting of corn silage and alfalfa hay Therefore optimal placement of these two forage source which could improve feed intake and milk production canbe a useful and important guide for making decisions in the dairy industry Therefore the purpose of thisexperiment was to evaluate the effect of different ratios of alfalfa hay to corn silage on production andreproductive efficiency in early and mid lactation Holstein dairy cows in summer The experimentaldesign was a completely randomized design with two treatments in two separated halls that each owns 60Holstein dairy cows The average MY 47 5 0 5 DIM 40 15 and parity 2 48 were about to be equalfor cows in each hall Cows were randomly assigned to the experimental diets Concentrate to forage ratiowas 60 to 40 for two experimental diets First experimental diet containing 50 corn silage as foragesource and 50 alfalfa hay and the ratio of corn silage to alfalfa hay for second experimental diet was75 25 Rations in terms of NEL 1 7 Mcal per kg DM CP 18 NDF 28 5 0 2 and NFC 42 0 3 were equal to each other Cows were fed mixed TRM twice a day 5 AM and 5 PM Cows within eachhall had free access to water and rock salt DMI of cows fed 75 corn silage diet was greater and tend tobe significantly higher P 0 06 in early lactation and in the middle and whole of lactation DMI of cowsthat were fed 75 corn silage diet was higher than 50 corn silage diet P 0 05 The MY P 0 01 andECM P 0 05 was also higher for 75 corn silage diet than 50 corn silage diet While due to highermilk fat content in dairy cows consuming 50 corn silage diet P 0 05 but 3 5 fat corrected milkwere not affected by treatments P 0 05 About the other components of the milk in all time periods thelactose content of milk tend to be significantly affected by treatments P 0 07 and fat to protein ratio ofmilk was significantly higher for 75 corn silage diet than 50 corn silage diet P 0 01 Although thepercentage of milk protein were similar among treatments but milk protein yield in mid lactation P 0 05 and total test period was higher for 75 corn silage diet than 50 corn silage diet P 0 07 BCS and its changes during experimental period were also affected by treatments so that cowsconsuming diets containing 75 corn silage as source of forage had higher BCS P 0 01 and in earlylactation these cows lost less BCS P 0 05 About the digestibility of dietary nutrients the resultsshowed that 75 corn silage diet in the early lactation had higher digestibility than 50 corn silage diet P 0 05 Feed efficiency ECM per DMI was significantly higher for 75 corn silage treatment than theother treatment P 0 05 Among the blood parameters only BUN was affected by treatments and inearly lactation and total lactation was significantly higher for 50 corn silage diet than 75 corn silagediet P 0 05 but in mid lactation was not affected by treatments P 0 05 In this study the reproductiveparameters were numerically higher for 75 corn silage diet but they were not affected significantly bythe experimental diets The results of these experiments showed that increasing the portion of corn silagefrom 50 to 75 as source of forage for dairy cows without affecting the reproductive parameters canimprove the productivity of Holstein cows Key words dairy cattle corn silage alfalfa hay performance reproduction

عرب سرخي تلك آبادي، محمد

اثر نسبت هاي مختلف سيلاژ ذرت به يونجه خشك بر بازده توليدي و توليد مثلي گاوهاي شيري هلشتاين در اوايل و اواسط شيردهي در فصل تابستان

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