Effect of Roughage to Concentrate Ratio in the Diet on Milk Production and Fatty Acid Profile of Milk in Crossbred Cows

摘要

Eighteen crossbred dairy cows were divided into three groups of six each and fed on rations containing different roughage: concentrate (R: C) ratios for a period of 60 days to investigate their effect on milk production and its fatty acid composition.The roughage (berseem hay: Trifolium alexandrinum) to concentrate ratio was 50: 50, 60: 40 and 70:30 in treatments T,, T2 and T3, respectively. DM intake decreased (P<0.05) with the increase in the level of roughage in the diet. Digestibility of DM, CP,EE, NFE and OM showed a significant (P<0.05) decrease whereas digestibility of CF and ADF increased significantly (P<0.05) with the increase in the ratio of roughage to concentrate. Increasing R: C ratio significantly (P<0.05) decreased milk productionbut production of 4% FCM was not affected by roughage level. Milk fat concentration decreased (P<0.05) by 6.30 and 3.78% in T and T , respectively as compared to Tr Increasing R: C ratio had no significant effect on milk lactose, protein, TS, SNF, MUN, Ca and P levels. Milk cholesterol in treatment T3 was lower by 13.35 and 8.27% as compared to T, and T2, respectively. The concentrations of TLCFA, TUFA, MUFA and PUFA in milk increased with the increase in roughage level in the diet whereas TSFA level was reduced. PUFA content of milk fat increased by 141.75% in T3 over T,. Total CLA production in T3 was increased by 50.92% over T,. Results of the present study indicated that cows producing 12-14 kg of milk/d could be best maintained on a dietary regimen of 70% good quality roughage and 30% concentrate to have maximum production beneficial fatty acids with lesser cholesterol without compromising milk yield.