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

Abstract

BACKGROUND: Methionine has been suggested as the firstlimitingamino acid for milk production in ruminants. It is importanthow to increase milk protein yield and milk fat in dairy ruminants.OBJECTIVES: This study was set to investigate the effect of rumenprotected methionine (RPMet) on milk composition of lactatingCashmere Rayeni goats. METHODS: 40 healthy singletonCashmere Rayeni goats about 3 to 4 years of age, at the first day oflactation, were randomly divided into 2 equal control andexperimental groups. The experimental group was supplementedwith 5 gr/day RPMet for 60 days. Milk samples of 2 groups weretaken on 30th and 60th days of the study. Milk protein, milk fat, milklactose, and milk Solids-not-Fat (SNF) were determined usingautomatic analyzer. The results were statistically evaluated withSPSS. RESULTS: The supplementation with RPMet did not effectall of the above mentioned parameters during the 60 days of theexperiment (p>0.05), except for the milk fat percentage of theexperimental group which showed significant increase after 60days (p<0.05). CONCLUSIONS: Our results about milk protein,milk lactose, and SNF were in agreement with previous studies thathad not shown significant differences. Results about milk fat on the30th day were in agreement with the results of several authors whoreported that RPMet did not affect milk fat percentage or yield;however, in the present study milk fat increased significantly on the60th day (p<0.05). To the best of the authors' knowledge, no studyabout the effects of RPMet on milk composition of CashmereRayeni goat has been done.