Supplementation of yearling steers grazing Northern Great Plains rangelands

Abstract

Growing yearling steers on summer rangelands as part of a cow-calf-yearling operation would allow producers to maximize forage utilization, and selling yearling steers when forage was in short supply would minimize potential genetic losses in the cow herd. A series of summer supplementation and intake studies were conducted from 1988-1992 to determine if weight gains of grazing yearling steers could be increased by supplemental energy (ground barley), phosphorus (P), or crude protein. Studies were conducted at 2 locations on pastures of approximately 51 ha each, which contained quite different mixtures of forage species. Forage P, crude protein and IVDOM levels were monitored throughout the grazing season. Supplementation results varied among years and between locations. There were significant (P < 0.14) location by treatment interactions in 1989 and 1990 because steers at the WEST location tended to respond more to supplementation than steers at the EAST location, but EAST location steers had the highest rates of gain. Providing supplements at gradually increasing rates produced results comparable to supplementing at a constant rate all summer. Supplemental crude protein showed no significant benefit, but crude protein levels in pasture forage were generally above steer requirements. Weight gains averaged over all 5 years were greater (P < 0.05) for steers supplemented with barley or barley and P, compared to unsupplemented control steers. The response to supplementation should be beneficial most years, but results may vary with the quantity and quality of available forage.

Self-limiting supplements fed to cattle grazing native mixed-grass prairie in the northern Great Plains1

“…Our results with HF support results reported by Karn (2000), who fed barley-based supplements (454 g/d) to grazing yearling steers in the northern Great Plains and increased gains 0.13 kg/d for supplemented steers compared to unsupplemented steers.…”

Influence of phosphorus supplementation on growth and reproductive characteristics of beef cows in the semi-arid bushveld of South Africa

“…In America, Karn (1995b) reported that with Hereford and Hereford-Angus crossbred replacement heifers, weight gains were not affected by phosphorus supplementation. He also found that yearling steers grazing northern plains responded inconsistently to phosphorus (Karn, 1995a). These results are in agreement with the results of Cohen (1972), Leche (1977), Winks (1990) and McLean et al (1990) who found that yearling steers in Australia, grazing on pasture low in phosphorus, did not respond to phosphorus supplementation in either the wet or dry season, as well as with Leche (1977) who obtained no response with steers in New Guinea.…”

“…McLean & Ternouth (1994) found that fertilizer phosphorus, and not phosphorus as a supplement, gave a positive response. Karn (1995a), Winks (1990) and McLean et al (1990) found that weight gain was not affected by supplementation in heifers. The lack of response was thought to be due to skeletal reabsorption and gastro-intestinal recycling of phosphorus.…”

“…In the United States, Black et al (1943) found that heifers were 57kg heavier at 18 months of age when given phosphorus supplementation, and Karn (1995a) found immediate weight gain response when Simmentaler crossbred heifers where given phosphorus supplementation. Phosphorus supplementation had a positive effect in South Africa, where even young cattle were suffering from 'styfsiekte', by alleviating symptoms of aphosphorosis and increasing weight gains (Theiler et al, 1927).…”

Competition and facilitation between a native and a domestic herbivore: trade‐offs between forage quantity and quality

“…Whereas forage quantity and N content results were consistent with earlier work, the limited effect on forage digestibility calls into question how prairie dogs may influence the intake of digestible nutrients by large herbivores. Grass protein content is often not a limiting factor for cattle during the growing season (Karn 2000, Grings et al 2004, whereas forage digestibility, which is linked to both plant protein and fiber content, can strongly influence ruminant mass gains.…”