Effect of feeding forage or concentrate starter diets early in life on rumen fermentation, metabolic response and growth of Wagyu-Friesian calves to 10 months of age

Context: Nutrition in early life can affect the long-term performance of livestock. Aims: This study evaluated the effects of rearing Wagyu x Holstein Friesian heifer calves either on a concentrate pelleted starter (CS; 90% DM, 19.3% crude protein (CP) and 13.8 MJ metabolisable energy (ME) per kg DM) or a forage starter (FS, ensiled alfalfa, Medicago sativa; 45% DM, 18.5% CP and 9.7 ME, MJ/kg DM) on growth, blood metabolites, carcass traits and meat quality. Methods: Calves (n=60) were allocated either to CS or FS diets. All calves were fed milk in group pens (n=10/pen) at 4 L/calf/day until week 7, then 2 L/calf/day for two weeks, and received their solid feeds ad libitum. Calves were transferred to pasture one week after milk removal, with starter feeds removed by 15 weeks. All heifers were then managed as one group on a pasture-based diet until slaughter at 26 or 30 months of age (average of 48 kg liveweight). Key results: Calves offered the CS diet were 14 kg heavier than calves on the FS diet at 15 weeks (P<0.001). However, liveweight was similar between groups by the time of slaughter (P>0.1). All blood parameters studied were similar (P>0.05) between treatments at 12 months and at slaughter. Depth of eye muscle and subcutaneous fat, measured using ultrasonography prior to slaughter, carcass weight and meat pH, marbling, shear force, moisture loss during cooking, total fat and fat and meat colour were also similar between treatments (P>0.05). Some potential was found for using blood markers to predict carcass traits and meat quality. Conclusions: Solid feed type during rearing had little effect on liveweight or meat characteristics from 12 months of age to slaughter of Wagyu x Friesian cattle. Implications: Calves can be reared on FS diets with similar long-term performance as on CS diets.