Environmentally friendly beef production from two genotypes fed cereal/molasses diets

Abstract

The role of sugar beet molasses, a by-product of the food industry, for producing environmentally friendlier beef than with less fossil energy-intensive grain was assessed with respect to growth, carcass merit and feed efficiency. Cattle investigated included bulls and heifers of Holstein×native Brown of Atlas (HB) or Holstein×Friesian (HF). Molasses included at 0, 20, 40 or 60% of total ration dry matter (DM) replaced barley in a typical grain-based diet. Cattle were individually fed ad libitum, from 180 to 420 kg and bulls were then slaughtered. Animals fed 0, 20, 40 or 60% molasses averaged 259, 257, 318 and 374 days on feed ( P<0.001), grew 0.96, 0.96, 0.72 and 0.69 kg/day ( P<0.0001), consumed 8.3, 8.9, 7.5 and 7.6 kg DM/day ( P<0.01), required 9.0, 9.5, 10.6 and 11.8 kg DM/kg live weight gain ( P<0.0001). Dressing percentage averaged 53.5% for cattle fed 0–40% molasses and was lower ( P<0.01) for cattle fed 60% molasses (50.8%). Faster gaining animals deposited more fat. Animal measures including feet (8.63 vs. 9.37 kg), carcass compactness (1.79 vs. 1.85 kg/cm), kidney, pelvic and heart fat (4.15 vs. 2.57 kg) and mesenteric fat (5.04 vs. 3.96 kg), differed ( P<0.05) for HB vs. HF, respectively. Whereas adding molasses above 20% somewhat decreased animal performance, this response was economically offset by the lower price of molasses. The economical optimum of molasses in the diet was 40%, whereas the positive environmental impact of reducing grain fossil energy needs improved through 60%. A feeding system based on 40% molasses in the diet, if applied to the ∼100 000 cattle in Morocco annually fed for meat production would save 47% of the barley grain otherwise needed while also converting 84% of the Moroccan sugar industry molasses by-product annually produced, to meet the meat-sourced food protein needs of Moroccan consumers in an environmentally friendlier meat protein production system.