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The objective of this experiment was to determine the relationships among enteric gas production, body weight (BW) gain, and feed intake for growing heifers consuming two energy divergent diets. Fifty-five fall born yearling Angus and Angus cross heifers were used in a 157-d experiment. Heifers were fed two consecutive diets at the Oklahoma State University Range Cow Research Center. Heifers were sorted into one of two drylot pens based on BW. Each drylot pen was equipped with individual intake monitoring system (C-Lock Inc., Rapid City, SD) with a stocking rate of 3.3 heifers per feeder. The first intake segment (HAY) was initiated with a 21 d of adaptation followed by 70 d of data collection. Heifers were offered ad libitum access to long stem unprocessed bermudagrass hay and a salt/mineral/vitamin supplement. After the HAY period, heifers were adapted to a 50% forage, 50% concentrate diet (TMR) during a 14-d adaptation period, followed by 52-d of data collection. Means and standard deviations for phenotypic traits of DMI, ADG, RFI, and CH4 were 6.7 ± 0.7 kg, 0.44 ± 0.13kg, and 194.6 ± 17.56 g/d respectively for HAY and 14.3 ± 1.34 kg, 1.72 ± 0.20 kg, and 280 ± 24.69 g/d respectively for TMR. Pearson correlations between diets for DMI, ADG, and CH4 were 0.32, -0.16, and 0.29, respectively. Coefficient of variation for DMI was 10.8% for HAY and 9.4% for TMR. Coefficient of variation for ADG was 29.9% for HAY and 11.6% for TMR. Methane intensity was calculated as CH4, g/day divided by DMI, kg/d resulting in 29.6 ± 3.5 and 19.9 ± 2.2 g CH4/kg DMI for HAY and TMR, respectively. In summary, HAY DMI was moderately and positively correlated with TMR DMI while ADG was not correlated among the two diet types. The HAY diet generated less total daily CH4, although more CH4 per unit of feed intake. [ABSTRACT FROM AUTHOR]

The article explores whether a genetic relationship exists between pulmonary arterial pressure (PAP) and feedlot performance and carcass traits. It considers the hypothesis that cattle with higher yearling PAP scores at high elevation would show a decrease in feedlot performance and an increase in fat-related CT when finished at moderate elevations. This study suggests that selection against high PAP does not negatively influence feedlot performance and carcass quality for future generations.

Genomic testing of feeder cattle is reported to be beneficial in selecting cattle for the feedlot, as well as making management and marketing decisions. The objective of this study was to determine differences in performance and efficiency of finishing steers with a range of Neogen Igenity Beef scores for average daily gain (ADG) and milk. Spring born steer calves from the Oklahoma State University Range Cow Research Center (n = 83, BW = 419 ± 31.9) of Angus ancestry were placed on feed at the Willard Sparks Beef Research Center on May 5, 2022, after grazing wheat pasture for 155 d. The steers were grouped based on Igenity ADG Score [low (1-4), medium (5-6), or high (7-10)] and Milk Score [low (1-5) or high (6-10)] based on the Igenity results. Steers were allocated into pens (n = 5 steers/pen) in heavy and light BW blocks. Steers were fed a step-up diet for 30 d before being switched to a finishing ration diet (8% prairie hay, 20% Sweet Bran and 62% dry-rolled corn). Cattle were fed ractopamine for 30 d before slaughter. The heavy block were on feed for 119 d, while the light block were on feed for 148 d. Data were analyzed as a randomized complete block design using the mixed procedure of SAS (SAS Inst. Inc., Cary NC) with pen as the experimental unit. Steers with high growth (HG) scores gained weight more rapidly during finishing and weighed more at slaughter than medium growth (MG) and low growth (LG; P < 0.01); while steers with high milk (HM) gained faster (P < 0.01) and tended (P = 0.06) to be heavier at slaughter than low milk (LM). Growth score was shown to have an effect on dry matter intake (P < 0.01) with HG consuming more feed than MG or LG. Cattle with HM scores were less efficient than LM scores (P = 0.01), but there was no difference (P = 0.37) in feed efficiency due to ADG score. Those with high growth and milk scores had a higher average daily gain (P < 0.01). These data indicate that Igenity ADG scores can be used to select cattle with higher performance and bodyweight at slaughter with no adverse effect on feed efficiency. Steers with higher Igenity Milk scores were less efficient than those with LM scores. Igenity Milk scores can be used to predict efficiency, according to these data. [ABSTRACT FROM AUTHOR]

Four years of feedlot performance and carcass characteristics were pooled on spring-(SPRING) and fall-(FALL) born steers (n=460) into a mixed model to evaluate the effects of calving season, sire breed (Angus [AN], Charolais [CHAR] or Hereford [HER]) and their interaction on feedlot performance and carcass traits. Initial and final BW, DOF, ADG, DMI, and G:F were evaluated as performance measures and HCW, YG, FT, REA, and MS were collected at harvest. There was no season by breed interaction for entry or final BW (P >0.05). SPRING steers (400.2 kg, 686.4 kg) weighed more than FALL (350.9 kg, 668.3 kg) upon entering and leaving the feedyard (P< 0.001). CHAR weighed 14.3 kg less than AN upon feedlot entry (P=0.01) although final BW did not differ by breed (P >0.05). SPRING steers (21.8 kg/d) consumed more feed than FALL steers (18.8 kg/d; P=0.002), but there was no difference in gain:feed due to calving season nor sire breed (P=0.575). A calving season by sire breed interaction was present for ADG and DOF (P=0.014). FALL AN (1.70 kg/d) and FALL HER (1.80 kg/d) gained more than FALL CHAR (1.55 kg/d;P< 0.001) and FALL AN were fed over a shorter period than FALL CHAR and FALL HER (P=0.006). However, average daily gain of SPRING calves did not differ by breed (P >0.05). There was a tendency for FALL (400.9 kg) steers to have lighter carcasses than SPRING steers (407.9 kg; P=0.068). HER carcasses were 18.0 kg heavier than AN carcasses (P< 0.001), but did not differ from CHAR (P=0.13). CHAR had larger REA (93.5 cm2) than both AN (87.7 cm2) and HER steers (88.5 cm2;P=0.001). Fall-born steers had less YG than spring-born steers (P< 0.042). Feedlot performance was generally less for fall-born steers finished during the winter months. Under these conditions, numerous performance and carcass traits were influenced by the interaction of breed and season. [ABSTRACT FROM AUTHOR]

The objective of this study was to evaluate the relationship between beef heifer feed efficiency and subsequent greenhouse gas emissions using an unprocessed hay diet. Fifty-four Angus and Angus Herford cross heifers were subject to a 71-day hay intake test using individual intake technology (C-Lock Inc., Rapid City, SD) with a stocking rate of 3.6 heifers per feeder. Heifers were blocked by BW into 2 drylot pens (HEAVY, n=21; LIGHT, n=33) at the Oklahoma State University Range Cow Research Center located near Stillwater, OK. Throughout the study, heifers were fed a long-stem, unprocessed, grass hay diet (10.8% CP, 2.0 Mcal ME, and 56% TDN) with 21-d adaptation. A subset of 39 heifers were used for the collection of gas flux data using an open-circuit, portable, gas-quantification system (GreenFeed, C-Lock Inc., Rapid City, SD) to measure (means±SD) oxygen consumption (3,118±330.9 g/d), carbon dioxide production (4,664±467.9 g/d), and methane production (169±23.4 g/d). Phenotypic measures (means±SD) for dry matter intake (DMI), average daily gain (ADG), average body weight (BW), and residual feed intake (RFI) were 6.75±1.12 kg, 0.15±0.2 kg, 312.7±30.5 kg, and 0.08±0.84 kg, respectively. Predicted DMI was calculated using a multiple regression equation (-3.11 + 0.13*BW0.75+0.76*ADG; P< 0.05; R2=0.43) in R. To further evaluate forage efficiency, heifers were segregated by 0.5 SD into three RFI categories of efficient (n=13), average (n=31), and inefficient (n=10) resulting in means of 5.8, 6.76, and 7.94 kg DMI and 0.16, 0.16, and 0.15 kg ADG, respectively. There was no significant difference (p< 0.05) between RFI categories for ADG, CO2, CH4, and O2. Phenotypic correlations of DMI with CO2, CH4, and O2 were 0.59, 0.45, and 0.61, respectively. Efficient heifers consumed 21% less forage compared with inefficient heifers, suggesting that improvement in forage utilization can be achieved when efficiency is evaluated using an unprocessed grass hay diet. [ABSTRACT FROM AUTHOR]