Milk production and milk fatty acid composition of grazing dairy cows supplemented with fodder beet

Abstract

A study was conducted to evaluate the effect of supplementing a perennial ryegrass-based diet with fodder beet on milk production and milk fatty acid (FA) composition, of dairy cows in early lactation. Sixty Friesian × Jersey cows, were blocked into six groups of 10 cows, and groups randomly allocated to three replicates fed either 18 kg DM/day of ryegrass herbage (H), or 14.4 kg DM/ day of ryegrass herbage + 4 kg DM of harvested FB bulbs (FBB). Dry matter intake (DMI) was similar between H and FBB (15.0±0.77 and 14.2±0.48 kg DM/day respectively). Although milk yield tended to be greater for H than FBB (20.0 and 18.9 kg/ day respectively; P=0.09); milk solids production was not affected by treatment (P=0.89). Supplementation with FBB increased the saturated (80.6 versus 73.2±0.39 g/100g FA; P<0.001) and medium chain milk FA (66.7 versus 56.2±0.783; P<0.001) content, compared with H. Under the conditions of the present study, our results suggest that, supplementing grazing dairy cows with FBB in early lactation, may not improve milk production and increases the saturated FA content of milk.