The effect of rumen protected methionine (RPMet) on milk composition of lactating Cashmere Rayeni goat

Background: methionine has been suggested as the first-limiting amino acid for milk production in ruminants. it is important how to increase milk protein yield and milk fat in dairy ruminants. objectives: this study was set to investigate the effect of rumen protected methionine (rpmet) on milk composition of lactating cashmere rayeni goats. methods: 40 healthy singleton cashmere rayeni goats about 3 to 4 years of age, at the first day of lactation, were randomly divided into 2 equal control and experimental groups. the experimental group was supplemented with 5 gr/day rpmet for 60 days. milk samples of 2 groups were taken on 30th and 60th days of the study. milk protein, milk fat, milk lactose, and milk solids-not-fat (snf) were determined using automatic analyzer. the results were statistically evaluated with spss. results: the supplementation with rpmet did not effect all of the above mentioned parameters during the 60 days of the experiment (p > 0.05), except for the milk fat percentage of the experimental group which showed significant increase after 60 days (p < 0.05). conclusions: our results about milk protein, milk lactose, and snf were in agreement with previous studies that had not shown significant differences. results about milk fat on the 30th day were in agreement with the results of several authors who reported that rpmet did not affect milk fat percentage or yield; however, in the present study milk fat increased significantly on the 60th day (p < 0.05). to the best of the authors' knowledge, no study about the effects of rpmet on milk composition of cashmere rayeni goat has been done.