Influence of Forage Species and Creep Grazing on a Cow-Calf System. I. Intake and Digestibility of Forages2

Abstract

To evaluate effects of forage quality and creep grazing on the digestibility and intake by cows and their calves on pasture we conducted a 2-yr study, using 36 cow-calf units randomly assigned each year to three replicated pasture treatments. The treatments were 2.6 ha of primarily Kentucky bluegrass and white clover (Native), 1.7 ha of tall fescue plus .9 ha of bluegrass-white clover (Fescue-Creep) and 2.6 ha of Kentucky 31 tall fescue (Fescue). Calves had access in the Fescue-Creep treatment to the bluegrass-white clover portion of the pasture but the cows were denied access through the use of a creep gate. In vitro dry matter digestibility of the pasture forages collected from esophageal-fistulated calves, was superior for the Native and Creep sections of the Fescue-Creep pasture in the spring and summer, with a general decline in digestible dry matter occurring for all treatments during the summer. Digestibility of the Fescue and Fescue-Creep pasture forages in the fall was increased over the summer values, as expected, while that of the Native pasture continued to decline, possibly because of limited forage availability. Overall, forage consumption by the cows was greatest in the spring, with that from the Native pastures greater (P<.05) than that from the other pastures. Mean forage consumption by the calves over the entire grazing season was 2.6, 2.4 and 2.2 kg•head−l•d−1, respectively, on the Native, Fescue-Creep and Fescue pastures, and all values differed (P<.05) from each sother. When forage intakes by suckling calves were expressed as g/kg BW.75, Fescue-Creep (59.7) was superior (P<.05) to Native (57.2), which in turn was superior to the Fescue treatment (54.3). Forage dry matter intake by the calves averaged 1.6, 2.1 and 3.5 kg•head−1•d−1 during the spring, summer and fall grazing periods, respectively. During the fall, forage intake by the calves on native pasture was higher than that by calves on the other treatments; conversely, comparatively lower levels of intake were observed for cows on the Native pasture. This indicates that forage consumption by the calves was not related to intake by the cows when pasture availability was limited. Results of this study show that when a higher quality forage is incorporated into a grazing system as a creep, forage consumption by the calves, on a BW.75 basis, can be equal to or greater than that of cows and calves grazing the same quality pasture.