Performance of heifers grazing native or introduced mixed warm-season grasses during summer months in south-central United States

Objective

This study compared weight gain and fecal egg count of heifers grazing native or introduced warm- season mixed-grass pasture.

Materials and Methods

Sixty fall-born, spring- weaned Angus crossbred heifers (8.5 mo old; 242 ± 26.9 kg) in each of 2 yr (2022 and 2023) were randomized to one of six 2.02-ha pastures (5 heifers/ha and 3 replicates per pasture type) of either native grass (NAT; predominately big bluestem [Andropogon gerardi Vitman]) or introduced mixed grass (WSMG; bermudagrass [Cynodon dactylon (L.) Pers.], crabgrass [Digitaria spp.], and foxtail [Setaria spp.]). Heifers grazed 84 d beginning the last week of May and were weighed every 28 d. Fecal samples were collected from each heifer toward the beginning and end of grazing for strongyle egg enumeration. Forage mass and nutritive value were assessed each time the cattle were weighed.

Results and Discussion

Forage mass and nutritive values differed for each year and pasture type. The NAT pastures had greater forage mass, lesser CP, and greater detergent fiber levels than WSMG. Season-long ADG differed by pasture type and year, with ADG being 0.22 kg/d greater in 2022 and 0.11 kg/d greater in 2023 for NAT. A forage system by sample day interaction in 2023 but not 2022 occurred with fecal egg counts.

Implications and Applications

At a fixed stocking rate, heifers continuously grazing native grasses dominated by big bluestem out gained heifers grazing mixed introduced warm-season grasses heavily infested with foxtails.