Effects of time of supplementation on cattle grazing annual ryegrass. III. Dry matter intake and digesta kinetics

Abstract

ABSTRACT Grazing behavior of ruminants can be affected by different management practices, such as time of supplementation. Nutrient utilization for forage-fed cattle can be optimized through the timing of supplementing nutrients within a day. Time of day of supplementation on DMI and ruminal kinetics parameters of beef cattle grazing annual ryegrass and supplemented with corn gluten feed (CGF) was evaluated using 8 (2 per treatment) ruminally cannulated crossbred heifers (initial BW = 351 ± 22 kg). Treatments were 1) control, nonsupplemented; 2) morning (0700 h) supplementation with 0.5% of BW of CGF; 3) noon (1200 h) supplementation with 0.5% of BW of CGF; or 4) afternoon (1600 h) supplementation with 0.5% of BW of CGF. When DMI was expressed as percentage of BW, it was greater (P = 0.03) in noon-supplemented heifers compared with those supplemented at 0700 h. Noon-supplemented heifers also had greater (P > 0.05) fluid passage rate and flow rate when compared with heifers supplemented in the morning hours. Particulate passage rate was lower (P = 0.03) for the morning-supplemented treatment when compared with the afternoon-supplemented group. Transient time decreased (P = 0.02) for the control treatment, when compared with noon-supplemented heifers. These data suggest that time of supplementation with CGF affected DMI and digesta kinetics variables associated with those changes in DMI. The effect of treatment on fermentation parameters and digestibility of forage, supplement, and nutritional entities should be investigated.