Supplementation based on protein or energy ingredients to beef cattle consuming low-quality cool-season forages: I. Forage disappearance parameters in rumen-fistulated steers and physiological responses in pregnant heifers1

Abstract

Two experiments evaluated the influence of supplement composition on ruminal forage disappearance, performance, and physiological responses of Angus × Hereford cattle consuming a low-quality cool-season forage (8.7% CP and 57% TDN). In Exp. 1, 6 rumen-fistulated steers housed in individual pens were assigned to an incomplete 3 × 2 Latin square design containing 2 periods of 11 d each and the following treatments: 1) supplementation with soybean meal (PROT), 2) supplementation with a mixture of cracked corn, soybean meal, and urea (68:22:10 ratio, DM basis; ENER), or 3) no supplementation (CON). Steers were offered meadow foxtail (Alopecurus pratensis L.) hay for ad libitum consumption. Treatments were provided daily at 0.50 and 0.54% of shrunk BW/steer for PROT and ENER, respectively, to ensure that PROT and ENER intakes were isocaloric and isonitrogenous. No treatment effects were detected on rumen disappearance parameters of forage DM (P ≥ 0.33) and NDF (P ≥ 0.66). In Exp. 2, 35 pregnant heifers were ranked by initial BW on d -7 of the study, allocated into 12 feedlot pens (4 pens/treatment), and assigned to the same treatments and forage intake regimen as in Exp. 1 for 19 d. Treatments were fed once daily at 1.77 and 1.92 kg of DM/heifer for PROT and ENER, respectively, to achieve the same treatment intake as percent of initial BW used in Exp. 1 (0.50 and 0.54% for PROT and ENER, respectively). No treatment effects (P = 0.17) were detected on forage DMI. Total DMI was greater (P < 0.01) for PROT and ENER compared with CON and similar between PROT and ENER (P = 0.36). Accordingly, ADG was greater (P = 0.01) for PROT compared with CON, tended to be greater for ENER compared with CON (P = 0.08), and was similar between ENER and PROT (P = 0.28). Heifers receiving PROT and ENER had greater mean concentrations of plasma glucose (P = 0.03), insulin (P ≤ 0.09), IGF-I (P ≤ 0.04), and progesterone (P = 0.01) compared to CON, whereas ENER and PROT had similar concentrations of these variables (P ≥ 0.15). A treatment × hour interaction was detected (P < 0.01) for plasma urea N (PUN), given that PUN concentrations increased after supplementation for ENER and PROT (time effect, P < 0.01) but did not change for CON (time effect, P = 0.62). In conclusion, beef cattle consuming low-quality cool-season forages had similar ruminal forage disappearance and intake, performance, and physiological status if offered supplements based on soybean meal or corn at 0.5% of BW.

76 Does supplemental protein and rumen-protected methionine improve performance and digestibility during late-gestation in beef cows?

“…Another study supplemented primiparous beef cattle fed an annual rye hay with soybean meal during the final trimester and for 58 d following parturition (Hess et al, 1998) and found that serum urea nitrogen concentrations tended to be elevated, and milk urea nitrogen concentrations with increased with protein supplementation post-partum (Hess et al, 1998). Similarly, plasma urea concentrations increased when gestating beef cattle were fed a soybean meal supplement vs. cows fed the basal diet containing 8.7% CP diet (Cappellozza et al, 2014). The researchers postulated that the elevated serum urea nitrogen was attributed to enhanced ruminal protein breakdown resulting in increased ammonia absorption by the rumen (Cappellozza et al, 2014).…”

“…Similarly, plasma urea concentrations increased when gestating beef cattle were fed a soybean meal supplement vs. cows fed the basal diet containing 8.7% CP diet (Cappellozza et al, 2014). The researchers postulated that the elevated serum urea nitrogen was attributed to enhanced ruminal protein breakdown resulting in increased ammonia absorption by the rumen (Cappellozza et al, 2014). This allowed for increased urea formation in the liver, promoting urea transport into the blood.…”

“…Mclean et al (2018) postulated that this increased insulin concentration in supplemented cattle was in response to an increased in available nutrients to the animal. Another study evaluated pregnant beef heifers fed a diet primarily containing low-quality cool-season forages, and fed either no protein supplementation (CON), or supplemented with soybean meal (PROT) at 0.50% of shrunken BW (Cappellozza et al, 2014). Heifers fed PROT had higher concentrations of plasma glucose and insulin (Cappellozza et al, 2014).…”

“…Another study evaluated pregnant beef heifers fed a diet primarily containing low-quality cool-season forages, and fed either no protein supplementation (CON), or supplemented with soybean meal (PROT) at 0.50% of shrunken BW (Cappellozza et al, 2014). Heifers fed PROT had higher concentrations of plasma glucose and insulin (Cappellozza et al, 2014). Thus, these studies suggest that blood glucose and insulin concentrations can be influenced by protein supplementation during late gestation, potentially increasing the animal's nutrient uptake, rate of protein synthesis, and(or) repartitioning of nutrients.…”

Effects of supplement type and narasin inclusion on supplement intake by Bos indicus beef bulls grazing a warm-season forage

“…Among the supplementation strategies available, mineral and/or protein-energy supplementation are often adopted in pasture-based systems. As an example, Fieser et al (2007) and Cappellozza et al (2014a , 2014b ) demonstrated that mineral only and protein-energy supplementation improved the performance of beef steers and heifers, respectively, compared with nonsupplemented cohorts. Nonetheless, the intake of salt-based mineral supplements is extremely variable among animals, year, and season ( Arthington and Swenson, 2004 ), but research in this area is very limited.…”