Exploring dietary quality characteristics related to milk yield of crossbred cows in Ethiopian smallholder farms : a clustering and multivariate analysis approach

The study, conducted on 70 smallholder dairy farms in Northern Ethiopia, aimed to evaluate whether variation in milk yield (in early and mid-lactation) of multiparous Holstein-Friesian crossbred cows is related to diet composition and quality. At early stage (1-120 days in milk (DIM)), a total of 70 dairy farms were used, while at mid-lactation (121-240 DIM), 54 dairy farms continued to be part of the study. K-means clustering was applied to group the cows based on energy-corrected milk yield (ECMY) into three milk production farm clusters (MPFC): Low MPFC (5.7-9.3 L/day), medium MPFC (9.4-12.8 L/day), and high MPFC (12.9-17.6 L/day). The dry matter intake (DMI) of cows during early lactation for high MPFC and low MPFC was 14.1 and 11.2 kg/day, respectively. The dietary proportion of crop residues in diets offered to crossbred cows tended to be lower in the high MPFC during early as well as in mid-lactation. Cows from the high MPFC consumed diets with higher (rumen degradable) protein levels both in early and in mid-lactation, while dietary fiber fractions and in vitro dry matter digestibility (IVDMD) only differed in early lactation. Multiple regression models indicated that DMI (kg/day) in combination with either neutral detergent fiber, crude protein, or IVDMD (g/kg DM) explained about 25% of the variation in daily ECMY expressed relative to body weight (mL/kg). Hence, higher milk production is linked to both increased DMI and better quality of diets