Timing of feeding orchestrates circadian post-feeding intake rhythms in once-daily fed dairy cows

The objective was to establish effects of feed presentation time and dietary forage to concentrate ratio on circadian postprandial rhythms of feed intake in lactating cows. Four multiparous and four primiparous Holstein cows were fed in a 4 × 4 Latin square design (with a 2 × 2 factorial arrangement of treatments) a higher (HC, forage to concentrate ratio = 38.5:61.5) or a lower (LC, forage to concentrate ratio = 50.6:49.4) concentrate total mixed ration (TMR) at either 21:00 h or 09:00 h. A metabolic acquisition system was used to monitor continuous feed intake electronically. Feeding at 21:00 h vs. 09:00 h increased feed intake within 3 h post-feeding, from 26 to 37% of total daily intake; with daily dry matter intake remaining unchanged. Results establish that evening instead of morning feeding increased eating rate shortly post-feeding, and thus, is a key regulator of postprandial circadian intake rhythms in lactating dairy cows.