A Comparison of Pearl Millet and Sorghum–Sudangrass Pastures during the Frost-Prone Autumn for Growing Beef Cattle in Semiarid Region

Leonard M Lauriault,Shad H Cox,Eric J Scholljegerdes,Leah H Schmitz

doi:10.3390/agriculture11060541

Abstract

Sorghum–sudangrass (Sorghum bicolor × S. sudanense (Piper) Stapf.) and pearl millet (Pennisetum glaucum (L.) R. Br.) provide adequate nutritive value for growing beef cattle; however, unlike pearl millet, sorghum–sudangrass produces hydrocyanic acid (which is toxic to livestock) when frosted. Forage yield, nutritive value, and weight gain of growing cattle grazing sorghum–sudangrass and pearl millet were compared during the frost-prone autumns of 2013 and 2014, at New Mexico State University’s Rex E. Kirksey Agricultural Science Center in Tucumcari, NM USA, in randomized complete block designs each year with two replicates. No differences existed between pearl millet and sorghum–sudangrass forage yield, although there was a year–forage interaction for fiber-based nutritive value components because of maturity differences across years between the forages when freeze-killed. Pearl millet allowed for extending grazing of available forage for an additional 14 and 24 d in 2013 and 2014, respectively, compared to sorghum–sudangrass during the frost-prone autumn periods. During that period, when sorghum forages produce potentially toxic levels of hydrocyanic acid, animals grazing pearl millet accumulated an additional average of 94.9 kg live-weight gain ha−1 (p < 0.001). These factors afford producers an opportunity to increase returns on the similar investments of establishing and managing warm-season annual forage crops each year, and allow more time to stockpile cool-season perennial and annual forages for winter and early spring grazing, or to reduce hay feeding.

Highlights

Semiarid regions are characterized by limited and erratic precipitation, high summer temperatures, and low soil fertility [1,2], as well as early autumn freezes [3] that are not predictable at spring planting time
Pastures were drilled with a 17.78 cm row spacing into conventionally tilled seedbeds on 28 June 2013 and 16 June 2014, and sprinkler-irrigated with treated municipal wastewater
Rabas et al [12] reported no difference among dry matter (DM) yield of varieties of sorghum–sudangrass and sudangrass

Summary

Introduction

Semiarid regions are characterized by limited and erratic precipitation, high summer temperatures, and low soil fertility [1,2], as well as early autumn freezes [3] that are not predictable at spring planting time. Ward et al [8] described sorghum–sudangrass and pearl millet as late-summer forage crops because they can be grown later than maize (Zea mays L.), and do not interfere with winter forage and grain crops for double cropping Both species respond to applied water and fertilizer [1,4,5], but forage production can still be influenced by the amount and distribution of precipitation [9]. The typical growth pattern of these two species can lead to an overabundance or shortage of forage at different times of the year [7] To overcome this concern, Fontaneli et al [5] recommended early and late plantings three to six weeks apart

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