Effect of morning vs. afternoon grazing on intramuscular fatty acid composition in lamb

The aim of this study was to assess whether different grazing management affect animal performance and meat fatty acid composition. Thirty-five lambs were divided into three groups: 12 lambs grazed from 9 am to 5 pm (8h group); 11 lambs grazed from 9 am to 1 pm (4hAM group) and 12 lambs grazed from 1 pm to 5 pm (4hPM group). The trial was conducted over 72 days. The 8h lambs had greater DMI (P < 0.0005) and final body weight (P < 0.05) than the 4hPM and 4hAM lambs while carcass weight was not different between the three groups. The meat of the 4hPM lambs contained greater (P < 0.05) percentages of polyunsaturated fatty acids, C18:2 cis-9 trans-11 and lower saturated fatty acids and C18:0 than the meat of the 8h and 4hAM lambs. It is concluded that allowing lambs to graze during the afternoon rather than during 8 h does not compromise the carcass yield and results in a healthier meat fatty acid profile.

Research Highlights► Three groups of lambs grazed 8 h per day (8h), 4 h in the morning (4hAM) or 4 h in the afternoon (4hPM). ► Carcass weight was similar between the three groups. ► The 4hPM meat contained more VA, RA, PUFA and less C18:0 and SFA than the 4hAM meat. ► Afternoon grazing does not compromise carcass yield and results in a healthy meat fatty acid profile.