Extension

Research conducted by the University of Saskatchewan compared growth performance and carcass characteristics for calves entering long or moderate backgrounding durations before finishing or direct finishing under conventional and natural management systems.1 The study was conducted over two years (October 2017 to January 2020) at the University of Saskatchewan’s Livestock and Forage Centre of Excellence at 3 field locations. Each year, 240 weaned steer calves with Angus-based genetics, free of preweaning hormonal implants, were purchased from an order buyer. Upon arrival, all animals were weighed on 2 consecutive days. The steers were allocated into 3 weight groups: (1) heavy (639 lb), (2) medium (545 lb), and (3) light (472 lb) over the 2 years. Cattle in each weight group were randomly allocated to 1 of 2 management system treatments: conventional or natural. Conventional treatments used hormonal implants and feed additives, but the natural treatment did not. Following a 41-day receiving phase, heavy steers entered direct finishing, medium steers entered a short backgrounding and finishing, and light steers entered a long backgrounding, grazing, and finishing. All steers were fed to a shrunk weight of 1367 lb (full weight X 0.96).

 

Throughout feeding conventional steers received growth-promoting implants: Ralgro (Merck Animal Health) on arrival and during the backgrounding phase, Revalor-G (Merck Animal Health) to light conventional stees during grazing, and Revalor-S (Merck Animal Health) during finishing. The only difference between conventional and natural diets during the feeding phases was the supplement pellet, which in the conventional diet contained monensin (Rumensin, Elanco Animal Health) and tylosin (Tylan, Elanco Animal Health) at levels of 30 grams/ton of dry matter (DM) and 11 grams/ton of dry mater (DM), respectively. Throughout all phases, feed wagon flushing was done between any conventional and natural feedings to prevent crossover of feed additives.

 

Steer performance during the receiving, backgrounding, grazing, and finishing phases in heavy, medium, and light weight groups under conventional and natural management systems over 2 years is shown in Table 1. Since the conventional animals received a Ralgro implant at the start of the receiving phase upon arrival, they had greater average daily (ADG; 3.11 vs. 2.30 lb/day, P < 0.001) than their natural counterparts during the 41-day receiving phase.

 

During the backgrounding phase, ADG for the medium group was ~19% greater (1.85 vs. 1.50 lb/day; P < 0.05) for conventional compared with natural. For the light group, ADG was ~21% greater (1.57 vs. 1.26 lb/day; P < 0.05)) for conventional compared with natural. No significant differences were observed for dry matter intake (DMI) between conventional and natural steers in the medium or light weight groups. Treatment affected (P < 0.05) the Gain:Feed ratio for both medium and light cattle, with conventional being ~13% and ~20% more efficient than natural cattle in the medium group (0.103 vs. 0.090) and light group (0.100 vs. 0.080), respectively. During the grazing phase for the light group, ADG did not differ (P = 0.585) between conventional and natural groups (1.04 vs. 1.17 lb/day).

 

During the finishing phase, conventional cattle gained 19% (3.97 vs. 3.20 lb/day, P < 0.01), 30% (4.81 vs. 3.35 lb/day, P < 0.01), and 34% (6.11 vs. 4.01 lb/day) more compared with natural in their respective wight groups (heavy, medium, and light). These greater gains were expected considering the numerous studies showing 10% to 30% greater ADG with the use of hormonal implants alone.2, 3 DMI was greater in the conventional treatment compared with natural (P < 0.05) in the medium (26.90 vs. 24.21 lb/day) and light groups (33.10 vs. 28.75 lb/day). Whereas DMI did not differ between treatments in the heavy group. Conventional cattle were 17% (0.196 vs. 0.163), 23% (0.179 vs. 0.138), and 25% (0.185 vs. 0.139) more efficient compared with natural cattle in their respective weight groups. The heavy, medium, and light groups of conventional cattle took 50, 71, and 59 fewer days on feed, respectively, to finish, relative to natural.

 

^a–eMeans within a row with different superscripts differ (P < 0.05).

¹CONV = conventionally raised cattle treatments using hormonal implants and feed additives; NAT = naturally or non conventionally raised cattle treatments, no hormonal implants and no feed additives.

²WtG = weight group; PET = performance-enhancing technology; WtG Å~ PET = interaction between WtG and PET. Adapted from Smith et al., 2024.

 

In reference to carcass data, the natural cattle produced greater marbling (520 vs. 405 where 500-599 = modest and 400-499 = small; P < 0.001), more backfat thickness (0.57 vs. 0.49 in; P < 0.001), and greater quality grades than conventional cattle. Rib-eye area was greater for conventional cattle (13.7 vs. 13.1 sq in; P < 0.001). As would be expected, feeding tylosin to the conventional cattle reduced the incidence of live abscesses compared to natural cattle (27.0 vs. 46.8%).

 

These researchers concluded that these data show that “steers managed without performance enhancing technologies under western Canadian conditions will have lower gains and efficiency, but greater days on feed to a target weight, quality grades, marbling, and backfat thickness, than conventionally-managed steers”. They also noted that the evidence of greater liver abscesses in natural system cattle suggests that poorer liver health and possible performance limitations are the trade-off for carcasses with greater quality grades, and marbling under a natural management system.

 

¹Smith, J., E. Darambazar, G. B. Penner, N. Erickson, K. Larson, J. McKinnon, D. Damiran, and H. A. (Bart) Lardner. 2024. Effects of conventional and natural management systems on backgrounding and finishing performance of beef steers. Applied Animal Science. 40:150–166. 

 

²Duckett, S.K., D.G. Wagner, F.N. Owens, H.G. Dolezal, and D.R.Gill. 1996. Effects of estrogenic and androgenic implants on performance, carcass traits, and meat tenderness in feedlot steers: A review. Prof. Anim. Sci. 12: 205-214.

 

³Preston, R.L. 1999. Hormone containing growth promoting implants in farmed livestock. Adv. Drug Deliv. Rev., 38:123-138.