Technical note: Impact of a molasses-based liquid feed supplement on the feed sorting behavior and growth of grain-fed veal calves

摘要

This study was designed to determine the effect of adding a molasses-based liquid feed (LF) supplement to a high-grain mixed ration on the feed sorting behavior and growth of grain-fed veal calves. Twenty-four Holstein bull veal calves (90.2 +/- 2.6 d of age, weighing 137.5 +/- 16.9 kg) were split into groups of 4 and exposed, in a crossover design with 35-d periods, to each of 2 treatment diets: 1) control diet (76.0% high-moisture corn, 19.0% protein supplement, and 5.0% alfalfa/grass haylage) and 2) LF diet (68.4% corn, 17.1% protein supplement, 9.0% molasses-based LF, and 4.5% alfalfa/grass haylage). Diets were designed to support 1.5 kg/d of growth. Data were collected for the final 3 wk of each treatment period. Feed intakes were recorded daily and calves were weighed 2 times/wk. Feed samples of fresh feed and refusals were collected 3 times/wk for particle size analysis. The particle size separator had 3 screens (19, 8, and 1.18 mm) and a bottom pan, resulting in 4 fractions (long, medium, short, and fine). Sorting was calculated as the actual intake of each fraction expressed as a percent of its predicted intake. Calves tended (P = 0.08) to sort for long particles on the control diet (110.5%) and did not sort these particles on the LF diet (96.8%). Sorting for medium particles (102.6%) was similar (P = 0.9) across diets. Calves sorted against short particles on the LF diet (97.5%; P = 0.04) but did not sort this fraction on the control diet (99.4%). Calves sorted against fine particles (79.3%) to a similar extent (P = 0.2) on both diets. Dry matter intake was similar across diets (6.1 kg/d; P = 0.9), but day-to-day variability in DMI was greater (0.5 vs. 0.4 kg/d; P = 0.04) when calves were fed the control compared with the LF diet. Calves on both diets had similar ADG (1.6 kg/d; P = 0.8) as well as within-pen variability in ADG (0.4 kg/d; P = 0.7). The feed-to-gain ratio was also similar between control and LF diets (4.3 vs. 3.9 kg DM/kg gain; P = 0.4). The results suggest that supplementation of a molasses-based LF to high-grain fattening veal calf diets can reduce variability in feed consumption, both within and across days.