Growth Of Steers Research Articles

12 Growth Performance, Physiology, and Carcass Merit of Supplementing Brahman Steers with Zilpaterol Hydrochloride Under Heat Stress Conditions

Abstract Supplementation with a β- adrenergic agonist (β-AA) for 21 days in Brahman steers under heat stress conditions (HS) was evaluated with respect to feedlot performance and carcass merit. Twenty-four Brahman steers (kg = 338 ± 39) were housed in two controlled environment chambers with one of two environmental (ENV) conditions 1) heat stress (HS; THI = 73 to 85) and 2) thermoneutral (TN; THI = 68) with either Zilpaterol hydrochloride (ZL) or soymeal supplementation (CN) using a randomly assigned in a 2 x 2 factorial design (n=6/group). Daily data were collected for dry matter intake, water intake, respiratory rate (RR), and rectal temperature (RT). At the end of 21 d period, total weight gain was used to calculate average daily gain (ADG) and gain to feed. Blood samples were collected from the jugular vein on days -7, 3, 10, and 21 for cortisol analysis, and biological impedance analysis (BIA) was determined on days 3, 10, and 21 on each animal. Steers were harvested at 544 kg on average post supplementation/environment conditions, and carcass merit was determined. There were no differences (P > 0.05) in feedlot performance. Brahmans exposed to heat stress had greater RR during the heat stress periods of the experiment, regardless of supplementation. Environment and day interactions (P < 0.04) were observed for RT, HS steers had a greater RT on d 8 but similar RT on d 15 and 19. Stressed steers with ZL had higher RT (P < 0.05) than TN/CN steers on d 11. There was no interaction (P > 0.05) between environmental conditions and CN and ZH supplementation for cortisol concentrations. Regardless of environmental treatment or supplementation, no difference (P > 0.05) was associated with BIA characteristics. There were no differences (P > 0.05) for hot carcass weight, cold carcass weight, USDA yield grade, 12th rib loin eye area, marbling score, KPH percentage, and 12th rib fat thickness between groups. Twelfth-rib loin eye area lean color from HS/CN had higher lightness (L*) (P < 0.05) than TN/CN steers. HS/CN steers present a similar (L*) to ZL in TN and HS conditions. Redness-greenness (a*) was greater (P = 0.01) in carcasses from HS steers with or without ZL than TN/ZL but similar to TN/CN. Steers exposed to HS and CN had a higher (P = 0.02) change of 12th rib lean color from yellow to blue (b*) than TN steers with CN and ZL. Supplementation with β-AA did not negatively impact growth, carcass performance, or carcass merit in heat-stressed steers.

86 Effects of Hurricane-Related Prenatal Stress on Postnatal Growth and Development of Steers and Heifers in a Limited Resource Beef cow-Calf System

Abstract Cost effective growth in beef calves is necessary for productivity of limited-resource pasture-based cow-calf operations. However, pasture-based production systems are often plagued by environmental stressors such as droughts, high ambient temperatures and adverse weather events that might impede calf growth and development. Our study evaluated the effects of prenatal stressors such as hurricanes on postnatal calf growth and development. Crossbred beef calves born from the same lineage in two different years were compared: Group 1, dams experienced effects of a category 5 hurricane in their late gestation. Group 2, dams experienced no adverse environmental effects their late gestation. Body weights and condition scores were collected at weaning, yearling age, 14 -15 months age and, and 20 months of age. Blood samples were collected periodically to evaluate metabolite and hormone profiles. Data were evaluated by mixed procedures of SAS, and significance determined at P< 0.05. Calf body weights during the juvenile periods were less (P< 0.05) in both steers and heifers born to dams that experienced hurricane-related stress during late gestation compared with their normal contemporaries. However, this weight difference was not evident during adult stages. Further, although blood cortisol was not different in yearling heifers, glucose and progesterone concentrations were decreased (P< 0.05; P< 0.01, respectively) in Group 1 heifers compared with the control group. In adult steers, serum cortisol differed (P< 0.001) between groups (965±38 vs 1282±40.5, pg/mL for Groups 1 and 2 respectively). Indeed, Group 1 steers exhibited decreased serum cortisol concentrations at both summer and fall periods when ambient temperatures were expected to present varied stressful challenges to the animals. Thus, detrimental effects of a natural disaster such as a hurricane may impede postnatal growth and development of heifers and steers as seen in this project. Further investigation is on this phenomenon is warranted. Funded by NIFA CBG # 2021-38821-34599.

349 Dietary Zinc and Ractopamine Elicit Changes in Gene Expression of Zinc Transporters in the Muscle of Finishing Beef Steers

Abstract Twenty-four Angus cross steers (467 ± 13 kg) were used to assess the effects of supplemental Zn and ractopamine (RAC; Actogain, Zoetis) on muscle gene expression. Steers were housed in pens (6 steers/pen) with GrowSafe bunks and randomly assigned to treatments (6 steers/treatment) which included 0 (CON), 60 (LO), 120 (MED), or 180 (HI) mg supplemental Zn (Availa-Zn, Zinpro)/kg dry matter. Dietary Zn treatments were initiated on d 0 and RAC supplementation (300 mg/steer/d) began on d 53. Blood and muscle (longissimus thoracis) samples were collected from all steers on d -4, 48, and 67. Plasma Zn concentrations were determined via inductively coupled plasma-mass spectrometry and muscle gene expression was determined via the Fluidigm Biomark HD system. Data were analyzed using ProcMixed of SAS (fixed effect = treatment; experimental unit = steer); treatments were compared using orthogonal linear and quadratic contrast statements. The LO treatment was removed from gene expression analyses due to poor reads. There was a tendency for a quadratic effect on d 48 and 67 plasma Zn (P = 0.10) where plasma was greater in Zn-supplemented animals than CON. Minimal effects of Zn supplementation were observed on muscle gene expression prior to the start of RAC. However, 14 d after the start of RAC, the expression of several genes involved in Zn storage and transport (MT1A, SLC39A7, SLC39A8, SLC39A9, SLC39A10, SLC39A13) linearly decreased with increasing Zn supplementation (P ≤ 0.08). These effects were mainly driven by an increase in gene expression for CON steers, suggesting RAC influences intracellular Zn trafficking or demand. Several of these transporters are located on organelles responsible for Zn-dependent processes like protein synthesis and metalation of enzymes. Therefore, increasing Zn supplementation prior to RAC feeding may support beta-agonist induced muscle growth in beef steers.

80 Effects of Prenatal Stress on Beef Steer Development

Abstract Cost-effective growth in beef steers is necessary for limited-resource grass-fed cow-calf operations. Therefore, production goals should emphasize using inexpensive feed sources to maximize growth post-weaning. Maternal stress during gestation can negatively affect this progression. Effects of prenatal stressors such as hurricanes have been overlooked. In this project two groups of steers born from the same lineage in different years were compared: Group 1, dams experienced effects of a category 5 hurricane in their late gestation. Group 2, dams experienced no adverse environmental effects. Body weights were collected at 13 (Period 1), 14 (Period 2), and 20 months of age (Period 3). Blood cortisol concentrations were evaluated in Summer (when Group 1 average age was 31 months, while Group 2 averaged 18 months of age) and Fall (when Group 1 average age was 34 months, while Group 2 average age was 21 months) periods. Data were evaluated by mixed procedures of SAS, and significance was declared at P< 0.05. The results showed a significant group effect on the age-matched body weights (572.96±22.04 vs 735.12±22.04, lbs. for groups 1 and 2 respectively). Period effect was also significant (P< 0.001). However, there was no group by period effect. Group 1 steers were lighter in body weight than Group 2 in periods one and two but were not different thereafter. There was a significant group effect on cortisol concentrations (965.24±38.21 vs 1,282.2±40.53, pg/mL for groups 1 and 2 respectively). Our results showed that the hurricane had detrimental effects on steers, which may impede the growth progression of animals as seen in this study. The observations made in this study indicate the need to investigate further the effects of prenatal stress by natural disasters on beef steer development.

PSII-B-12 Association of Glucose Metabolism with Feed Intake, Growth, and Efficiency of Beef Steers

Abstract The objective of this experiment was to determine the association of glucose metabolism and insulin sensitivity with dry matter intake (DMI), average daily gain (ADG), and feed efficiency (G:F) of steers fed a finishing diet. Steers (n = 55; initial body weight 518 ± 26.7 kg) were subjected to an intravenous glucose tolerance test (IVGTT) where glucose was dosed through a jugular catheter and serial blood samples were collected. Three days after the final IVGTT, steers began a 63-d DMI and ADG test. Body weight was measured on d 0, 1, 21, 42, 62, and 63, and DMI was measured using an Insentec Roughage Intake Control system (Insentec, Markenesse, The Netherlands). Peak insulin concentration in response to the IVGTT tended to be correlated with ADG (r = 0.25; P = 0.07) and DMI (r = 0.23; P = 0.09), indicating cattle with greater ADG and DMI tend to require a greater insulin release in response to glucose. Glucose nadir concentrations were correlated with ADG (r = 0.27; P = 0.044) and G:F (r = 0.37; P = 0.005). Additionally, when steers within 0.5 standard deviations of the mean for DMI are classed as displaying high- or low-ADG, glucose nadir was greater in high-ADG steers (P = 0.042). The association of greater glucose nadir with high-ADG could indicate that high-ADG steers do not clear glucose as efficiently as low-ADG steers, potentially indicating reduced insulin sensitivity. Carcass marbling score was negatively correlated with area under the glucose curve (r = -0.38; P = 0.006), glucose clearance rate (r = -0.33; P = 0.016), and glucose nadir concentration (r = -0.40; P = 0.004). These results indicate that glucose metabolism and insulin signaling are associated with growth, efficiency, and carcass quality, but the molecular mechanisms that drive these effects need to be elucidated.

The features of morphological and biochemical blood parameters and linear growth of steers of different origin

The growth of beef production is possible with an increase in the number of young cattle on rearing and fattening. In the Russian Federation over-replacement young cattle of dairy breeds are mainly used for this purpose. However, the transfer of dairy cattle breeding to industrial production technologies has led to a reduction in livestock for fattening. This raises the question of the development of specialized beef cattle breeding and the increase in the number of beef cattle. The purpose of the work was to study the features of morphobiochemical indicators of blood and linear growth of beef steers of diff erent origin. The data on the results of hematological studies of Aberdeen-Angus steers and their crossbreds with Black-and-White breed have been presented in the paper. The changes in the shaped elements and biochemical parameters of the blood by the periods of rearing steers were analyzed. It was found that crossbred animals had higher rates than their purebred herdmates. A higher content of erythrocytes and hemoglobin was observed in crossbred young animals. This indicates more intensive redox processes occurring in the body and its respiratory function, which corresponds to the increase in productivity. It was found that with the age of animals in the experimental groups, there was the decrease in the blood level of hemoglobin and erythrocytes with slight fl uctuations in leukocytes, which is a common biological pattern of growth and development of animals. With a higher level of albumins in the blood, the average daily weight gain was also higher. At 3 months of age, crossbred steers had the highest average daily gains in live weight. They had by 2,3 % higher albumin content than purebred herdmates. A comparative evaluation of the linear growth of experimental steers of the beef productivity direction revealed certain diff erences in the main measurements and conformation indices; a tendency to improve beef forms in crossbred animals was noted.

Comparison of Pure and Crossbred Japanese Black Steers in Growth Performance and Metabolic Features from Birth to Slaughter at a Spanish Fattening Farm.

Simple SummaryCattle growth performance is a determinant of beef production. Nowadays, customers demand specialized, high-quality beef products produced according to stringent health and welfare standards. Intramuscular fat, or marbling, improves beef quality, and the Japanese Black (Wagyu) is the breed with the highest rates of marbling. Wagyu steers are reared under specific conditions in Japan, which may differ from the conditions in other countries, and these differences may affect animal well-being and, therefore, growth rates and beef quality. The current study shows that purebred Wagyu and crossbred Wagyu-by-Angus steers that were raised at a cow–calf operation and fattening system in Spain with no exercise restriction, high welfare, and a local diet high in olein content showed appropriate growth and fattening rates, health status, and metabolic development. Wagyu crossbred steers did not show substantially faster growth than purebred Wagyu animals, so they may not be as profitable as purebred Japanese Black in this type of production system.Japanese Black (Wagyu) cattle produce high-quality beef. However, whether Wagyu steers can be profitably raised under conditions different than the traditional Japanese ones remains unclear. From 2018 to 2020, we raised 262 Wagyu purebred steers, 103 Wagyu-by-Angus (Wangus) crossbred steers, and 43 Angus-by-European (ACL) crossbred steers on a Spanish farm with high welfare standards and a locally sourced, high-olein diet. Factors and factors’ interactions impacting steer growth were analyzed using generalized linear models. ACL steers grew faster than the other two groups, with Wangus showing intermediate fattening and muscle development. Average daily weight gains (kg/day) were 0.916 for Wagyu, 1.046 for Wangus, and 1.293 for ACL during the weaning to growing period, and 0.628 for Wagyu, 0.64 for Wangus, and 0.802 for ACL during the growing to fattening phase. ACL showed the lowest marbling rates. Wagyu and Wangus usually showed higher cholesterol, triglycerides, and high-density lipoprotein than ACL. ACL calves may experience greater stress at weaning, as suggested by higher glucose, lactate, and β-hydroxybutyrate than the other groups. The results suggest that Wagyu and Wangus steers showed adequate growth, health, and metabolic development in this type of production system, with Wagyu purebreds probably being more profitable than Wangus crossbreeds.

The early story of growth hormone-releasing factor in rats, swine, and cattle

Following the discovery of the growth hormone-releasing factor from a human pancreatic tumor by the group of Guillemin at the Salk Institute in California, research on this factor has exploded. This review article is focused on the results obtained early after this discovery and summarizes the biological effects of this releasing factor on the rat digestive system development and above all on pig, steer, and gilt growth as well as on milk production in lactating sows and cows.

203 Effect of Feed Intake and Calcium Salts of Palm Oil Inclusion on Growth Performance and Carcass Characteristics of Feedlot Finishing Steers

Abstract Fifty-nine Angus×SimAngus-crossbred steers [body weight (BW) 279 ± 16 kg] were used to evaluate the effect of different dry matter intake (DMI; FS) with or without the inclusion of palm oil calcium salts (4% dry matter basis; CSPO) on growth and carcass characteristics of feedlot steers. Steers were blocked by BW and randomly assigned to individual pens. Treatments (2×2 factorial) consisted of ad-libitum ground corn (GC)-based diet without (ANF) or with (AWF) the inclusion of CSPO, or 85% of the DMI of the ANF treatment without (RNF) or with the inclusion of CSPO (RWF). After weaning, steers were fed a corn silage-based diet for 30-d and subsequently placed in a GC-based diet. Both diet types were offered ad-libitum or at 85% of the ANF intake and with or without CSPO. After 59-d in the finishing diet, all steers had ad-libitum access to feed. All data were analyzed with a mixed model considering the fixed effect of treatments, time and their interaction, and random effect of block. There were FS×CSPO interactions (Table 1; P ≤ 0.01) for BW, DMI, average daily gain (ADG) during the first 106-d. After all steers were switch to ad-libitum, restrictedly fed steers had greater (P ≤ 0.01) ADG and ADG:DMI ratio (G:F) compared with ad-libitum fed steers. No treatment differences (P ≤ 0.21) were observed for final BW (FBW), and overall DMI, and G:F. No treatment or their interactions (P ≥ 0.34) were detected for any carcass characteristic (Table 2) except for longissimus muscle area (LMA, P = 0.07), where CSPO inclusion tended to increase the LMA of steers fed ad-libitum but did not differ from restricted steers. Therefore, differences in growth as a consequence of intake restrictions during the growing and early finishing stage could be mitigated once cattle are allowed ad-libitum access to feed.

225 Effect of Increasing Doses of Encapsulated Butyric Acid and Zinc on Beef Feedlot Steer Growth Performance, Dietary Net Energy Utilization, and Carcass Characteristics

Abstract The objective of this study was to determine the effects that increasing doses of encapsulated butyric acid and zinc (BPZ) have on beef feedlot steer growth performance, dietary net energy utilization, and carcass characteristics. Steers (n = 272; shrunk BW = 360 kg ± 74 kg) were assigned to dietary treatment [0 (CON), 1, 2, or 3 g BPZ/kg diet DM] in a randomized complete block design (RCBD) with pen (n = 32) as experimental unit. Cattle were fed until visually assessed to have 1.27 cm rib-fat and were shipped for harvest at a commercial beef abattoir. Carcass and liver health data was recorded. Feedlot performance data was calculated on a carcass-adjusted basis (HCW/0.625). Data were analyzed as a RCBD with fixed effects of BPZ inclusion level and block was considered a random effect; pre-planned contrasts for CON vs. BPZ, plus linear, and quadratic responses were tested. No differences (P ≥ 0.14) were observed for final BW, DMI, ADG, feed conversion efficiency, observed dietary NEm and NEg, observed-to-expected dietary NEm and NEg, HCW, REA, rib-fat thickness, marbling score, estimated EBF, or distribution of USDA YG 1, 3, 4, 5, and USDA quality grade among treatments. A tendency (P = 0.10) was observed for CON vs. BPZ for calculated YG. Tendencies were detected for USDA YG 2 carcass distribution (linear; P = 0.07) and for normal and abscessed liver prevalence (quadratic; P = 0.08). Dressed yield tended to be greater (P = 0.08) for BPZ vs. Con and increased with dose (linear; P = 0.05). Supplementation of BPZ in finishing cattle diets does not appreciably influence growth performance, but increases dressed yield. Data from this study suggests that the addition of BPZ to feedlot finishing diets for decreasing the prevalence of abscessed livers should be further investigated.

193 Impact of Corn Silage Moisture And/Or Kernel Processing at Harvest on Finishing Steer Growth Performance, Efficiency of Dietary Net Energy Utilization and Carcass Traits

Abstract Steers (n = 192; initial shrunk BW = 446 ± 28.3 kgs) were used in a 112-d finishing experiment Treatments were arranged in a 2 x 2 factorial (24 pens total; 8 steers/pen) to evaluate corn silage moisture [1/2 to 2/3 milk line (ML) and black line (BL)] and kernel processing at harvest on finishing steer growth performance and carcass traits. Steers were blocked by batch fraction (n = 6) and pen as the experimental unit. The model included the effects of harvest time, processing, and their interaction. Block was included as a random factor. No harvest time x KP interaction was detected (P ≥ 0.28) for any growth performance related parameters. No Harvest time × KP interaction was detected (P ≥ 0.26) for any parameters related to the efficiency of dietary NE utilization. Comparative NEm for harvest time indicates that delayed harvest enhanced corn silage NEm by 6% and KP decreased apparent NEm value of corn silage by 9% compared with current feeding standards. No harvest time × KP interaction (P ≥ 0.08) was detected for any carcass traits except the distribution of USDA Prime carcasses (P = 0.04). Steers from ML/KP- had the fewer (P = 0.05) USDA Prime carcasses compared with ML/KP+, BL/KP-, and BL/KP+. Harvest time (P ≥ 0.07) and KP (P ≥ 0.07) had no appreciable influence on any carcass trait parameters. These data indicate that corn silage harvest can be delayed without detriment to growth performance and kernel processing does not enhance the apparent feeding value of corn silage when corn silage is fed as the sole roughage component of a feedlot finishing diet (i.e., 20% inclusion DM basis).

96. Intake, growth and carcass traits of steers offered grass silage supplemented with barley- and maize-based rations containing flaked peas, flaked beans, maize dried distillers grains or maize gluten feed

96. Intake, growth and carcass traits of steers offered grass silage supplemented with barley- and maize-based rations containing flaked peas, flaked beans, maize dried distillers grains or maize gluten feed

Alfalfa biotypes with putative enhanced cell wall digestibility and effects on performance of growing beef steers.

Three alfalfa biotypes were chosen based on the presumption that they would be sources of alfalfa herbage that differed in lignin concentration and therefore cell wall digestibility. The hypothesis was that a lesser lignin concentration would result in greater alfalfa neutral detergent fiber (NDF) digestibility and greater beef steer growth performance. The three alfalfa biotypes were HarvXtra (Forage Genetics International), Hi-Gest 360 (Alforex Seeds), and a control alfalfa, LegenDairy XHD (Winfield Solutions LLC). High-moisture wrapped bales were prepared from second-harvest, d 30 crops. Digestibility of NDF was determined using in vitro incubations and a steer digestibility trial. Alfalfa baleage and trace mineral salt were fed to Angus steers (300 kg initial body weight, 4 pens/treatment) in an 83-day growing-phase trial. Alfalfa acid detergent lignin concentrations were 75.6, 71.8, and 63.0 g/kg dry matter (P = 0.34) for LegenDairy, Hi-Gest and HarvXtra, respectively. Based on in vitro total-tract NDF digestibility coefficients, HarvXtra tended (P ≥ 0.09) to have the highest NDF digestibility. Alfalfa biotype affected in vivo apparent total tract digestibility of NDF (P < 0.001) and there was a trend for an effect on acid detergent fiber digestibility (P = 0.051). Hi-Gest and HarvXtra had similar in vivo apparent NDF digestibilities, which were greater than for LegenDairy (P < 0.05). There was no alfalfa biotype effect on daily alfalfa dry matter intake (DMI; P = 0.51) or average daily gain (P = 0.25) by growing steers. The absence of an effect by the novel alfalfa biotypes on DMI by growing steers suggests that the compositional and digestibility differences of the novel alfalfa biotypes compared to LegenDairy were not sufficient to alleviate the limitation of physical fill (if evident) on DMI. If more disparity in cell wall composition and NDF digestibility were to exist between control and reduced-lignin biotypes, then perhaps an advantage in cattle growth performance for a reduced-lignin alfalfa biotype would be detectable.

Hay Nutritional Quality and Grassland Bird Nesting: Impact of Delaying First Hay Cut on Dairy and Beef Production in Ontario

Perennial forage production exists in Ontario to support the livestock industry, but also provides nesting habitat for grassland birds such as the threatened Bobolink (Dolichonyx oryzivorus) and Eastern Meadowlark (Sturnella magna). Delaying hay harvest until July 15 or later allows most nestling birds to leave the nest, but the nutritional value of hay decreases substantially. This project estimated the nutritional and economic impact of delaying the first hay cut until after July 15 on beef and dairy production in Ontario, Canada. Forage crops were sampled across Ontario, analysis of nutritional value performed, and effects on production and economics modelled. 634 samples were collected over 13 weeks at 16 sites from May 21 to August 14 during 2014 and 2015. As expected, nutritional quality declined over the season. Crude protein decreased by 5.2%, total digestible nutrients by 7.7%, neutral detergent fibre digestibility (NDFd48) by 20.1%, while lignin increased by 3.5%, neutral detergent fibre by 13.1%, and acid detergent fibre by 9.9%. Estimated yearly milk production decreased 10.9 kg or C$7.87/dairy cow for each day of delay in harvest (2017 values). Estimated growth of backgrounding beef steers decreased 1.56 kg or C$5.49/head for each day of delay in harvest. This translated into lost revenue per acre for backgrounding steers of C$31 per acre and C$45 per acre for over wintering beef cows for a delay from mid-June to mid-July. Some agri-environmental incentives in Canada, US and Europe offset the reduced revenue due to lower quality forages. This analysis informs farmers about the cost of practices to benefit grassland birds and provides empirical data on how to structure stewardship incentives for these practices.

Effect of pre-grazing herbage mass on pasture production and performance of suckler-bred steers during the grazing season and subsequent indoor finishing period

The objective was to determine the effect of pre-grazing herbage mass (PGHM) on herbage production and nutritive value, intake and growth of suckler-bred steers in a rotational stocking system, and the residual effects on intake, growth and carcass traits during subsequent indoor finishing. A total of 108 yearling steers previously offered grass silage indoors over 105 days were assigned to one of two PGHM (1500 – low (L) or 2000 – high (H) kg dry matter (DM)/ha; > 4 cm) treatments. Steers (ca. 345 kg at turnout to pasture in spring) rotationally grazed perennial ryegrass (Lolium perenne) dominant pasture in 12 groups of 9 for 203 days. At the end of the grazing season they were housed indoors and offered either (1) grass silage only or (2) grass silage + 3.17 kg concentrate DM/head daily for 136 days until slaughter at 24 months of age. Annual herbage production was higher (8427 vs. 7542 kg DM/ha, P < 0.01) for H than L, but there was no difference between treatments in surplus herbage removed as silage due to the tendency for H steers to consume more herbage/ha while grazing (7363 vs. 6479 kg DM/ha, P = 0.08). During the grazing season, compared to L, steers grazing H had a greater estimated herbage DM intake (6.59 vs. 5.93 kg DM/ha, P < 0.001), daily live weight gain (0.81 vs. 0.76 kg, P < 0.01), live weight at the end of the grazing season (553 vs. 539 kg, P < 0.01) and live weight gain/ha (1261 vs. 1206 kg/ha). During the indoor finishing period there was no PGHM × finishing diet interaction, and no residual effect of PGHM on daily live weight gain, but carcass weight tended to be heavier for H (359 vs. 354 kg, P = 0.06) than L. Compared to silage only, the silage + concentrates group had a higher (P < 0.001) total DM and energy intake, feed conversion efficiency, live weight gain, carcass weight and carcass conformation and fat score. In conclusion, grazing the lower PGHM reduced herbage production, steer live weight gain at pasture, overall live weight gain/ha and tended to reduce carcass weight; therefore, under the conditions of this experiment grazing a PGHM of 2000 kg DM/ha is recommended. Removing concentrates from the finishing diet reduced carcass weight and fatness, making it more difficult to finish steers at a commercially acceptable carcass (carcass fat score > 6.0, 1 - 15 scale).

270 Evaluation of Steer Implant Strategies for Long-season Grazing of Cool-season Annuals

Abstract The objective of this study was to determine the relative effects of stocker-phase implant strategies on growth and carcass characteristics of beef steers. In each of 2 locations (OK and MS), steers were grazed on cool-season annual pastures in fall 2018 through spring 2019. Steers (n = 300 in MS, n = 240 in OK) were randomly assigned to one of three implant treatments, 1) a single Synovex® One Grass implant at d 0, 2) a single Component® TE-G with Tylan implant at d 0, or 3) a reimplant treatment receiving Component® TE-G with Tylan at d 0 and again at d 82 (OK) or 85 (MS). Steers from each treatment were commingled in 2 (OK) or 3 (MS) pastures for 159 (OK) or 161 d (MS). Following grazing, steers were shipped to a commercial feedyard for finishing, sorted into 3 pens based on BW with each treatment equally represented in each pen, and were managed according to that site’s BMPs. Steers from all treatments were implanted identically in the feedyard. Steers were slaughtered when the pen was visually estimated to be at 1 cm backfat. Carcass data of individuals were collected by camera grading equipment in the packing plant. Data were analyzed as a completely random design with animal as the experimental unit, treatment as a fixed effect, and pasture within location as a random effect. Marbling score tended to be greater in the single Component® TE-G with Tylan (treatment 2) vs. the other 2 treatments (425 vs 408 and 410, P = 0.07). No other production variables, including stocker-phase ADG, approached a significant difference (P &amp;gt; 0.39). No evidence was found to recommend stocker-phase reimplanting even in relatively long stocker phases with high ADG, and producers should consider selecting the most cost-effective implant at grazing initiation.

PSVIII-15 Effect of Endovac-Beef vaccination on performance, dietary energetics, and carcass characteristics of growing-finishing calf-fed Holstein steers

Abstract Objectives were to evaluate the influence of ENDOVAC-Beef® (Endovac Animal Health, Columbia, MO) vaccination on calf-fed Holstein steer growth performance, dietary energetics, and carcass characteristics. Fifty Holstein steer calves were utilized in a 322 d trial. Calves were blocked by initial shrunk body weight (134 ±5 kg) and randomly assigned to treatments within weight groups to 10 pens (5 steers per pen, 5 pens per treatment). Five pen groups received the ENDOVAC-Beef vaccination on d 28 and d 56, and the remaining 5 pens did not receive the ENDOVAC-Beef vaccination. All steers were fed the same steam-flaked corn-based growing-finishing diet. Vaccination did not affect (P ≥ 0.10) live weight, average daily gain, and dry matter intake during the 322 d feeding period. However, vaccination increased (P ≤ 0.04) gain efficiency and estimated dietary net energy values (NE) during the first 112 d on feed. Vaccination did not affect (P ≥ 0.14) gain efficiency or estimated dietary NE during the final 112 to 322 d, or over the entire feeding period (1 to 322 d). Vaccination did not affect (P ≥ 0.31) hot carcass weight, dressing percentage, and marbling score. However, vaccinating calf-fed Holstein steers with ENDOVAC-Beef increased (P ≤ 0.01) longissimus muscle area (LMA; 86.5 vs 76.8 cm2) and retail yield (51.3 vs 50.4); but, tended to increase (P = 0.07) carcass fat thickness. Morbidity and pink eye infection were low and not affect by treatment (P ≥ 0.18). We conclude that while vaccinating calf-fed Holstein steers with ENDOVAC-Beef did not have an overall effect on growth-performance, it increased (13%) LMA and retail carcass yield (1.8%).

Мясная продуктивность бычков казахской белоголовой породы при использовании в кормлении лактулозосодержащих добавок

Aim. Study of the effect of lactulose-containing feed additives on the growth and meat productivity of Kazakh white-headed steers. Materials and Methods. The research was carried out on the basis of the A.N. Sobolev’s farm enterprise, Uryupinsky district, Volgograd region. For the experimental work, 30 heads of the Kazakh white-headed steers at the age of 8 months were selected. The animals were divided into three groups. Each group consisted of 10 animals. The steers of the control group received a general economic diet, consisting of pasture forage with the addition of 2.5 kg of concentrated feed; analogues of experimental group I received the feed additive "Laktuvet-1" in addition to the concentrates; experimental group II – feed additive "Kumelact-1". Feed additives were introduced in an amount of 0.5% by mass of the concentrated feed. The diet of experimental young animals were calculated to obtain average daily gain at the level from 950 to 1000 g. The growth of animals was assessed according to the data of monthly individual weighing and determination of live weight, absolute and average daily gain. The slaughter of experimental animals was carried out according to the method of VNIIMS (1984). All the material presented in the article was processed using standard biometric methods (according to the method of Plokhinsky N.A., 1969) using software Microsoft Office package and determination of the Student-Fischer difference probability criterion. Results. As a result of the studies, it was found that the animals of experimental groups I and II began to surpass significantly steers of control group from the age of 11 months. At the age of 15 months, their superiority in live weight was 9.4 kg, or 2.19% (P≥0.95), and 21.3 kg, or 4.97% (P≥0.999), respectively. The advantage of the animals of experimental groups I and II over the steers of control group in terms of the average daily gain was 4.62 (P≥0.99) and 10.98% (P≥0.999), respectively, for the entire period of the experiment. The results of the control slaughter indicate that the steers that received feed additives exceeded the analogous of control group in carcass yield by 0.10 and 0.30%; fat yield – by 0.10 and 0.20%; slaughter yield – by 0.20 and 0.24%, respectively. Conclusion. The use of feed additives "Laktuvet-1" and "Kumelaсt-1 in the diets of experimental young animals contributed to an increase in live weight and an improvement in the slaughter qualities of cattle. The highest effect was found in the group of animals that received the feed additive "Kumelact-1".

Beef productivity of steers when feeding protein-vitamin-mineral additive and protein-vitamin-mineral concentrate

The purpose of the work was to study the influence of protein-vitamin-mineral additive and protein-vitamin-mineral concentrate on the growth, development and meat productivity of steers. Studies have been carried out on the rearing of steers when using the protein-vitamin-mineral additive based on extruded soybean with bentonite in the preweaning period and the protein-vitamin-mineral concentrate (with urea concentrate) when fattening steers. During the first research and production experiment in the calves of the 1st experimental group 30 % and in the bovine calves of the 2nd experimental group 40 % milk replacer have been replaced with a protein-mineral-vitamin additive. At the beginning of the experiment the calves of all groups had almost the same live weight. Starting from the age of 1,5 months the growth of the animals of the experimental groups began to prevail over the control group. Thus, the bull calves of the 1st experimental group at 2 months of age were larger than the control ones by 5,1 %, by the end of the experiment their superiority was 7,6 % (P &lt; 0,01). The total gain in live weight of the bull calves of the 2nd experimental group was 9,4 % higher (P &lt; 0,001) than in the control group. During the second research and production experiment on the use of protein-vitamin-mineral concentrate the difference in feeding was that the steers of the experimental group consumed complete feed, which included protein-vitamin-mineral concentrate (with urea concentrate) and bentonite. The gain in live weight of calves for 5 months of experiment in the control group was 136,7 kg, and in the experimental group it was 11,4 % more. The expenditures of feed per 1 kg of gain in EFU were by 10,1 % lower in the experimental group compared to the control group. The level of profitability of beef production in the control group was 16,1 %, and in the experimental group it was 26,5 %, which was more by 10,4 abs.%.

162 Increasing Concentrations of Supplemental Zinc Influence Performance, Carcass Characteristics, and Trace Mineral Status of Non-implanted and Implanted Steers

Abstract One hundred twenty-eight Angus-cross steers (492 ± 29 kg) were utilized in a 2 × 4 factorial to determine the effects of dietary Zn within implant strategy on performance, carcass characteristics, and Zn status. Factors included Zn supplemented at 0, 30, 100, or 150 mg/kg dry matter ([DM]; Zn0, Zn30, Zn100, Zn150, respectively) from ZnSO4 and implant administered on d 0 as no implant (NoIMP) or Component TE-200 (TE-200; Elanco, Greenfield, IN). Cattle were stratified by bodyweight (BW) to GrowSafe equipped pens of 5 or 6 steers and assigned to pen-wide treatments (experimental unit of steer; n = 16/treatment). Steers were weighed on d -1, 0, 18, and 59 with blood collected on -1, 18, and 40. Via Proc Mixed of SAS, linear and quadratic effects of Zn within implant treatments and assessment of NoIMP vs. TE-200 were tested for performance, carcass characteristics, and plasma data, with initial value covariates. Plasma Zn concentrations on d 18 and 40 linearly increased within NoIMP and TE-200 (P ≤ 0.03) and were lesser for TE-200 than NoIMP on d 18 (P = 0.001). Zinc linearly increased (P ≤ 0.002) d 18 BW and d 0–18 average daily gain (ADG). Within TE-200, Zn increased dressing percentage (P = 0.01) and tended to increase hot carcass weight (P = 0.09) linearly. Carcass-adjusted final BW and overall ADG tended to increase (P = 0.10) linearly within TE-200, with no Zn effects within NoIMP (P ≥ 0.18). Implanting increased carcass-adjusted final BW 13 kg over NoIMP (P &amp;lt; 0.0001). Overall feed efficiency quadratically increased within NoIMP (P = 0.01) peaking at Zn100 with no observed Zn effects within NoIMP or TE-200 for overall DM intake (P ≥ 0.15). These data suggest implant-induced growth in steers may require dietary Zn above current national recommendations.