The effects of ıntramuscular ınjections of vitamin b12 on production performance of dairy cows in early lactation fed dietary supplements of rumen-protected methionine

Abstract

To study the effects of rumen-protected methionine and vitamin B12 as well as their interactions on production performance of dairy cows in early lactation, 16 Holstein cows in early lactation in experiment with randomized complete block design with the 2×2 factorial arrangement used for 42 days. In this experiment, there were four treatments, which in each treatment is placed two cows primiparous and two cows multiparous. Treatments included: 1) The group receiving the basal diet, 2) The group receiving the basal diet with vitamin B12 injections, 3) The group receiving the basal diet with rumen-protected methionine, 4) The group receiving the basal diet with vitamin B12 injections and rumen-protected methionine. The results showed that in the use of vitamin B12 and rumen protected methionine, there is no significant difference between the experimental groups in the dry matter intake, milk production, energy corrected milk, 4% fat corrected milk, fat, protein, lactose, solids, solids-non-fat and urea. Analysis of variance showed that the experimental unit in the second and sixth weeks of experiment there were statistically significant differences in dry matter intake. Use of vitamin B12 can increase the milk production in early lactation, but this increase was not significant and in the case of vitamin B12 associated with methionine this effect is more evident.