Effects of genotype and concentrate supplementation on milk composition and selected milk processability parameters in late-lactation spring-calving grazing dairy cows

A 2 x 2 factorial design experiment was conducted to investigate effects of cow genotype and concentrate supplementation (CS) on milk composition and processability. Four treatment groups (n = 12) were: (i) lower milk genotype (LM) offered no CS; (ii) LM + 2.7 kg dry matter (DM) CS; (iii) higher milk genotype (HM) offered no CS; and (iv) HM + 2.7 kg DM CS. Cows were +208 d in milk, grazed full time, and were offered 17 kg DM pasture cow-1 d-1. Increased milk yield resulted from HM cows and offering CS. The HM cows had decreased fat, protein and casein concentrations, while offering CS also decreased fat, protein and casein concentrations. Milk from cows offered CS had increased ethanol stability compared with cows offered pasture-only. In conclusion, HM cows and offering CS increased milk yield at the expense of components, but offering CS increased milk colloidal stability. (C) 2020 The Authors. Published by Elsevier Ltd.

Automated summary

The experiment showed that high milk-producing genotype cows and offering concentrate supplementation (CS) can increase milk yield, but also decrease the concentrations of fat, protein, and casein in the milk. Additionally, milk from cows offered CS exhibited better ethanol stability compared to cows offered pasture-only.