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Feeding cattle in intensified settings allows cow-calf producers to decrease their reliance on grazed forage and utilize alternative feedstuffs. Under intensification diet type may alter energy utilization. Fourteen pregnant MARC III (1/4 Angus, 1/4 Hereford, 1/4 Red poll, and 1/4 Pinzgauer) heifers (405 ± 44 kg BW) were used to determine effects of diet type on nutrient and energy utilization. Heifers were randomly assigned to 1 of 2 treatments, a forage diet (FORAGE; 2.16 Mcal ME/kg) or a concentrate diet (CONC; 1.98 Mcal ME/ kg), and individually fed to meet maintenance energy requirements (0.135 Mcal ME/kg BW0.75). The CONC diet contained corn stalks (15%), dry-rolled corn (78%), soybean meal (4%) and a premix pellet (3%); FORAGE contained corn stalks (82%), corn silage (10%), soybean meal (4%) and a premix pellet (4%). Measurements of intake and digestion were measured over a 96-h period after approximately 21 d of adaptation. Using portable headbox calorimeters, measurements of O2, CO2, and CH4 gases were collected over a period of 24 h to determine individual heifer oxygen consumption, carbon dioxide production, and methane production. Data were analyzed as a RCBD with diet as fixed effect and measurement group as a random block. Intake of OM was greater for CONC (74.6 g/kg BW0.75) than FORAGE (68.0 g/kg BW0.75; P < 0.01), but NDF intake was greater in FORAGE (57.4 vs 27.2 g/kg BW0.75). Digestion of OM and NDF were greater (P ≤ 0.03) for CONC (78.5 and 56.2%, respectively) than FORAGE (53.4 and 47.3%, respectively). Intake of DE and ME were greater for CONC (15.84 vs 9.37 Mcal and 13.54 vs 7.38 Mcal; P < 0.01). The ratio of ME to DE was greater for CONC (0.85 vs 0.79; P = 0.01). Although methane production and heat production relative to GE were not different between treatments (6.2 and 57.5%; P ≥ 0.15), the methane production as % of DE was greater (P < 0.01) for FORAGE than CONC (12.6 vs 8.0 % of DE). Retained energy was 1.61 Mcal/d for CONC compared to -3.17 Mcal/d for FORAGE; P < 0.01). Similarly, retained nitrogen was greater in CONC than FORAGE (-1.59 vs -35.68 g/d; P < 0.01). Feeding concentrate-based rather than forage-based diets improved energy efficiency. The ratio of ME to DE may be dependent upon diet and more dynamic than previously thought. [ABSTRACT FROM AUTHOR]

Intensified cow-calf systems may reduce exposure to weather risk and land costs. Perceived costs and managerial requirements may prevent some producers from capturing benefits associated with intensified systems. This study evaluated differences in production response to management strategies for intensive cow-calf systems. Ninety-five mid-gestation cows (503 ± 151 kg) were stratified by weight, BCS, age, and days of gestation and assigned to 1 of 12 pens for a 112-d randomized complete block design experiment. Treatments were: limit-fed, total mixed ration (TMR), roughage and concentrate portions of the limit-fed TMR separated and fed 12 h apart (SEP), and ad libitum bermudagrass hay (7.7% CP, 1.19 Mcal NEm/kg; HAY). Treatments were applied prior to calving; following 112 d application, all cows were placed on common pasture and managed uniformly. Limit-fed treatment diets were wheat straw (35%), cracked corn (29%), dried distiller's grains (27%), and premix (9%) formulated to contain 1.56 Mcal NEm/kg and fed to deliver 80% of NRC (2000) predicted NEm requirements. Requirement for MP was exceeded by 141 g/d (TMR and SEP) and 455 g/d (HAY). Body weight, BCS, and back fat measures were made every 28 d. Treatment did not affect final BW (518.4 kg; P = 0.72), BCS (5.6; P = 0.67), or back fat thickness (0.70 cm; P = 0.45). Weight changes from d 0 to 112 did not differ (P = 0.17) and were 8.1, 16.6, and 22.9 kg for HAY, SEP, and TMR, respectively. However, weight change for cows fed SEP and TMR were different from zero (P ≤ 0.01). Cows fed HAY lost BCS (-0.25) from d 0 to 112, while cows fed SEP and TMR gained BCS (0.12 and 0.09, respectively; P < 0.01). Limit-fed strategies resulted in greater RE than HAY (P = 0.06; 137.1, 98.9, and -14.6 Mcal for TMR, SEP, and HAY, respectively). No differences were observed between treatments for cow BCS at calving (5.0; P = 1.00) or calf birth weight (33.7 kg; P = 0.36). By 45 d after calving, cow BW, cow BCS, and calf BW were not significantly different (P > 0.66) and averaged 486.4 kg, 4.8, and 74.2 kg, respectively. Limit-feeding a TMR or separate delivery of roughage and concentrate sustained cow performance compared to ad libitum hay consumption, and these results can be used to develop economic models to aid producers in decision making. [ABSTRACT FROM AUTHOR]

Intensified cow-calf systems may reduce exposure to weather risk and land costs. Perceived costs and managerial requirements may prevent some producers from capturing benefits associated with intensified systems. This study evaluated differences in production response to management strategies for intensive cow-calf systems. Ninety-five mid-gestation cows (503 ± 151 kg) were stratified by weight, BCS, age, and days of gestation and assigned to 1 of 12 pens for a 112-d randomized complete block design experiment. Treatments were: limit-fed, total mixed ration (TMR), roughage and concentrate portions of the limit-fed TMR separated and fed 12 h apart (SEP), and ad libitum bermudagrass hay (7.7% CP, 1.19 Mcal NEm/kg; HAY). Treatments were applied prior to calving; following 112 d application, all cows were placed on common pasture and managed uniformly. Limit-fed treatment diets were wheat straw (35%), cracked corn (29%), dried distiller's grains (27%), and premix (9%) formulated to contain 1.56 Mcal NEm/kg and fed to deliver 80% of NRC (2000) predicted NEm requirements. Requirement for MP was exceeded by 141 g/d (TMR and SEP) and 455 g/d (HAY). Body weight, BCS, and back fat measures were made every 28 d. Treatment did not affect final BW (518.4 kg; P = 0.72), BCS (5.6; P = 0.67), or back fat thickness (0.70 cm; P = 0.45). Weight changes from d 0 to 112 did not differ (P = 0.17) and were 8.1, 16.6, and 22.9 kg for HAY, SEP, and TMR, respectively. However, weight change for cows fed SEP and TMR were different from zero (P ≤ 0.01). Cows fed HAY lost BCS (-0.25) from d 0 to 112, while cows fed SEP and TMR gained BCS (0.12 and 0.09, respectively; P < 0.01). Limit-fed strategies resulted in greater RE than HAY (P = 0.06; 137.1, 98.9, and -14.6 Mcal for TMR, SEP, and HAY, respectively). No differences were observed between treatments for cow BCS at calving (5.0; P = 1.00) or calf birth weight (33.7 kg; P = 0.36). By 45 d after calving, cow BW, cow BCS, and calf BW were not significantly different (P > 0.66) and averaged 486.4 kg, 4.8, and 74.2 kg, respectively. Limit-feeding a TMR or separate delivery of roughage and concentrate sustained cow performance compared to ad libitum hay consumption, and these results can be used to develop economic models to aid producers in decision making. [ABSTRACT FROM AUTHOR]