Feeding amount affects the sorting behavior of lactating dairy cows

摘要

Miller-Cushon, E. K. and DeVries, T. J. 2010. Feeding amount affects the sorting behavior of lactating dairy cows. Can. J. Anim. Sci. 90: 1-7. The objective of this study was to determine whether feed sorting behavior in dairy cattle is influenced by the amount of feed provided. Six lactating Holstein cows, individually fed a total mixed ration once daily, were exposed to two treatments in a crossover design with 7-d periods. The treatments were: (1) lower feed amount (LEA; target 10% orts), and (2) higher feed amount (FIFA; target 20% orts). Dry matter intake (DMI) was monitored daily for each animal. On the final 4 d of each treatment period, fresh feed and orts were sampled for particle size analysis. The particle size separator had three screens (19, 8, 1.18 mm) and a bottom pan, resulting in four fractions (long, medium, short, fine). Sorting was calculated as the actual intake of each particle size fraction expressed as a percentage of the predicted intake of that fraction. Actual orts percentage averaged 11.5% for the LEA and 18.0% for the H FA treatments. When on the HFA cows sorted for the medium particles to a greater extent than on the LEA (103.0 vs. 101.1%). Further, when on the FIFA treatment cows sorted against short particles to a greater extent than on the LEA (95.2 vs. 98.6%). Despite greater sorting on the HFA treatment, the concentrations of neutral detergent fiber (NDF; 29.6%) and starch (27.1%) in the feed consumed were similar between treatments. Given this, and that DMI was greater on the H FA treatment compared with the LEA treatment (29.7 vs. 26.5 kg d(-1)), greater intakes of NDF (8.7 vs. 7.8 kg d(-1)) and starch (8.0 vs. 7.2 kg d(-1)) were also observed on the H FA treatment. The results suggest that, despite causing greater feed sorting, increasing the feeding amount for lactating dairy cows promoted higher DMI and did not prevent the consumption of a ration balanced to meet their nutritional requirements.