Interrelationships of forage and steer growth dynamics on wheat pasture

Abstract

Little information is available comparing animal performance or stocking stability for different wheat (Triticum aestivum L.) cultivars. Wheat is annually planted on 10 million ha in the Southern Great Plains. Our objective was to determine the effects of wheat cultivars with different forage production potentials on the seasonal and total productivity of steers. 'Lancota' and 'NK Pro 812'(NK 812) were planted in September 1987 and October 1988 at the W.T. Waggoner Ranch in north Texas. Hereford steers (Bos taurus L.), 220 to 233 kg. were grazed from November 1987 to May 1988 and December 1988 to April 1989. Seasonal and total forage production and disappearance were affected (p<0.05) by season and year. Cultivar did not affect forage production and disappearance. Steer average daily gain (ADG), gain head-1, and gain ha-1 were significantly affected by year, season, year x season, and cultivar x season interactions. Steer gain ha-1 was lower (P<0.10) in year 2 than year 1 for both cultivars. Both gain head-1 and gain ha-1 were lower (P<0.10) on NK 812 than Lancota in year 2. Season long gain ha-1 followed similar trends to gain head-1. A season x year interaction (P<0.05) occurred because NK 812 matured earlier and was less winter hardy than Lancota. Across years steer ADG increased with herbage allowance up to 27.3 kg 100 kg BW-1 Day-1 and further increases in herbage allowance had limited effect on steer ADG. Yearly variation in environmental conditions had greater effects on steer performance and forage production than cultivar.