Steer Calves Research Articles

Influence of Angus and Belgian Blue bulls mated to Hereford × Brahman cows on growth, carcass traits, and longissimus steak shear force1,2

Steers and heifers were generated from Angus (A) and Belgian Blue (BB) sires mated to Brahman x Hereford (B x H) F(1) cows to characterize their growth, carcass traits, and LM shear force. A total of 120 B x H cows purchased from 2 herds and 35 bulls (14 A and 21 BB) produced calves during the 5-yr project. After the stocker phase, a representative sample of A- and BB-sired heifers and steers were transported to the Iberia Research Station to be fed a high-concentrate diet. The remaining cattle were transported to a commercial feedlot facility. Each pen of cattle from the commercial feedlot was slaughtered when it was estimated that heifers and steers had 10 mm of fat or greater. The BB-sired calves were heavier at birth (P < 0.01) than the A-sired calves. During the feedlot phase, the A-sired calves gained more BW (P < 0.05) than the BB-sired calves. The BB-sired calves had heavier (P < 0.01) carcass weights than the A-sired calves. This was due to a combination of a heavier final BW and greater dressing percent. Because of their greater muscling and reduced (P < 0.01) fat, carcasses from BB-sired calves had greater yield (P < 0.01) compared with carcasses from A-sired calves. Carcasses from A-sired calves had a greater (P < 0.01) marbling score and greater (P < 0.01) USDA quality grade than carcasses from BB-sired calves. Tenderness, as measured by shear force of the steaks aged for 7 d, was similar for A- and BB-sired calves. However, steaks aged for 14 d from the A-sired calves had a reduced shear force (P < 0.01) compared with steaks from the BB-sired calves. Steer calves were heavier (P < 0.01) at birth and weaning, and had more total BW gain in the feedlot, which resulted in a heavier final BW and HCW compared with the heifers. Steer carcasses also had greater marbling scores and quality grades, whereas the heifer carcasses had larger LM area per 100 kg of carcass weight. In conclusion, the BB-sired calves had heavier carcass weights and greater cutability, whereas the A-sired calves had a greater degree of marbling and greater quality grade, and steaks from carcasses of A-sired calves were more tender as measured by shear force at 14 d.

Winter grazing system and supplementation during late gestation influence performance of beef cows and steer progeny1

ABSTRACTA 2 × 2 factorial study evaluated effects of cow wintering system and last trimester CP supplementation on performance of beef cows and steer progeny over a 3-yr period. Pregnant composite cows (Red Angus × Simmental) grazed winter range (WR; n = 4/yr) or corn residue (CR; n = 4/yr) during winter and within grazing treatment received 0.45 kg/d (DM) 28% CP cubes (PS; n = 4/yr) or no supplement (NS; n = 4/yr). Offspring steer calves entered the feedlot 14 d postweaning and were slaughtered 222 d later. Precalving BW was greater (P = 0.02) for PS than NS cows grazing WR, whereas precalving BCS was greater (P < 0.001) for cows grazing CR compared with WR. Calf birth BW was greater (P = 0.02) for CR than WR and tended to be greater (P = 0.11) for PS than NS cows. Prebreeding BW and BCS were greater (P ≤ 0.001) for CR than WR cows and PS than NS (P = 0.006) cows. At weaning, CR cows were heavier (P < 0.001) than WR cows but had similar BCS (P = 0.74). Cow weaning BW and BCS were not affected (P > 0.32) by PS. Calf weaning BW was less (P = 0.01) for calves from NS cows grazing WR compared with all other treatments. Pregnancy rate was unaffected by treatment (P > 0.39). Steer ADG, 12th-rib fat, yield grade, and LM area (P > 0.10) were similar among all treatments. However, final BW and HCW (P = 0.02) were greater for steers from PS-WR than NS-WR cows. Compared with steers from NS cows, steers from PS cows had greater marbling scores (P = 0.004) and a greater (P = 0.04) proportion graded USDA Choice or greater. Protein supplementation of dams increased the value of calves at weaning (P = 0.03) and of steers at slaughter regardless of winter grazing treatment (P = 0.005). Calf birth and weaning BW were increased by grazing CR during the winter. Calf weaning BW was increased by PS of the dam if the dam grazed WR. Compared with steers from NS cows, steer progeny from PS cows had a greater quality grade with no (P = 0.26) effect on yield grade. These data support a late gestation dam nutrition effect on calf production via fetal programming.

Relationships among measures of growth performance and efficiency with carcass traits, visceral organ mass, and pancreatic digestive enzymes in feedlot cattle1,2

Ninety-three crossbred steer calves (BW+/-SD=385+/-50 kg) were used (n=48 steers in yr 1, n=45 steers in yr 2) to examine the relationship among carcass traits, lean, bone, and fat proportions, visceral tissue weights, and pancreatic digestive enzyme activity with DMI, ADG, G:F, and residual feed intake. Calves were progeny from crossbred dams predominantly of Angus and Simmental breeding and were sired by Angus, Simmental, crossbred (predominantly of Angus and Simmental breeding), Charolais, or Piedmontese bulls. Steers were fed a high-moisture corn-based diet for an average of 112 d. Partial correlation analysis accounting for year, pen within year, week of slaughter within year, and sire breed was conducted. Gain:feed was negatively correlated (P <or= 0.04) with backfat thickness (r= -0.38), marbling score (r= -0.32), and trim and kidney fat weight proportion (g/kg of BW; r= -0.42). Residual feed intake (P=0.008; g/kg of BW; r=0.34) and backfat-corrected residual feed intake (P=0.005; r=0.29) were positively correlated with trim and kidney fat weight proportion. Gain:feed was negatively correlated (P<0.001) with total fat weight proportion (g/kg of rib; r= -0.45) and positively correlated (P <or= 0.03) with lean weight proportion (g/kg of rib; r=0.30) and bone weight proportion (g/kg of rib; r=0.28). Gain:feed was negatively correlated (P <or= 0.01) with subcutaneous fat weight proportion (g/kg of rib; r= -0.32) and intramuscular fat weight proportion (g/ kg of rib; r=0.37). Gain:feed was negatively correlated (P<0.001) with total visceral weight proportion (g/kg of BW; r= -0.44) and visceral fat weight proportion (g/kg of BW; r= -0.41) but was positively correlated (P=0.02) with spleen weight proportion (g/kg of BW; r=0.30). There were no significant correlations (P>0.10) between performance measures and the pancreatic proportional content of alpha-amylase and trypsin activity (units/kg of BW). These data indicate that carcass fatness traits and changes in the proportional weight of total viscera may be negatively associated with G:F and that visceral fat weight proportion and trim and kidney fat weight proportion may be important factors influencing this relationship.

Evaluation of Dry Distillers Grains Plus Solubles Inclusion on Performance and Economics of Finishing Beef Steers

A 167-d feedlot study was conducted to evaluate feeding increasing levels of dry distillers grains plus solubles (DDGS) to finishing cattle and the impact on performance and profitability. Crossbred steer calves (n = 240, BW = 306 ± 24.5 kg) were used in 30 pens with dietary treatments of 0, 10, 20, 30, and 40% DDGS dietary inclusion (DM basis). Quadratic relationships (P 0.15) by DDGS level, but G:F tended to be quadratic (P = 0.10) as 20% DM inclusion had the greatest value, although steers fed all levels of DDGS had numerically greater G:F compared with steers fed no DDGS. Carcass characteristics, other than hot carcass weight, were not affected by DDGS treatment. Energy value of DDGS at 10 to 40% dietary inclusion resulted in a quadratic trend (P = 0.10) and remained above corn, with the highest values at 10 and 20% inclusion averaging 127% of corn. When DDGS was priced equally to corn, all levels of DDGS from 10 to 40% inclusion resulted in higher profits compared with a dry-rolled corn based diet regardless of corn price. The greatest returns were observed when cattle were fed 20% DDGS. These data indicate that DDGS can be fed up to 40% DM to improve cattle performance and result in economic profits, with optimum levels at 20 to 30% diet DM.

Performance and bunk attendance of cattle fed steam-rolled or ground corn supplemented with laidlomycin and chlortetracycline or monensin and tylosin

British cross steer calves (n = 240; 332 ± 23 kg) in 16 pens were fed ground (G) or steam-rolled (SR) corn-based finishing diets medicated with 12 mg kg-1 laidlomycin propionate and 42.2 mg kg-1 chlortetracycline hydrochloride (LC) or with 30.4 mg kg-1 monensin sodium and 10.5 mg kg-1 tylosin phosphate (MT) in a 2 × 2 factorial experiment. Individual bunk attendance was monitored using radio frequency identification in one pen per diet. Finishing diets were fed for 125 d following a 27-d adaptation from 65 to 91% concentrate diet. In the first 56 d and overall, daily dry matter intake (DMI) was greater (P &lt; 0.05) with LC than with MT (8.8 vs. 8.3 kg), but did not differ (P = 0.97) between G and SR diets. There was a trend (P = 0.11) towards greater ADG for cattle fed LC than those fed MT (1.54 vs. 1.47 kg d-1), but gain:feed was similar (0.169; P = 0.80) between antibiotic supplements. Processing method did not (P = 0.29) affect rate of gain, but SR tended (P = 0.06) to improve gain:feed compared with G (0.171 vs. 0.165). Steers fed LC spent more (P &lt; 0.001) time at the bunk than those fed MT (125 vs. 120 min d-1). On G diets, cattle fed LC made fewer daily visits (9.3 vs. 9.5 visits d-1; P = 0.03), but spent more time at the bunk (135.9 vs. 124.0 min d-1; P &lt; 0.001) resulting in greater duration per meal (15.4 vs. 13.7 min meal-1; P &lt; 0.001). These cattle also had the greatest deviation in daily duration at the bunk (37.3 vs. 33.7 min; P &lt; 0.001). The prevalence of liver abscesses was 13.2% with LC and 6.5% with MT (P = 0.09). However, the prevalence of severely abscessed livers (2.9%) was unaffected (P = 0.45) by treatment. The prevalence of foot rot was greater (P = 0.02) for cattle fed MT (7.5%) than for cattle fed LC (0.8%). Compared with feeding MT, feeding LC may enhance ADG, possibly due to greater DMI. Key words: Beef, chlortetracycline, corn processing, laidlomycin, monensin, tylosin

Nonionophore antibiotics do not affect the trans-18:1 and conjugated linoleic acid composition in beef adipose tissue1

The common practice in North American feedlot industries is to add antibiotics to the diet to prevent disease and improve both BW gain and feed efficiency. In this study, 240 crossbred steer calves were backgrounded on a 54% silage diet for 80 d and fed a finishing diet consisting of 81% barley grain, 10% barley silage, and 7.5% supplement (DM basis) with and without in-feed antibiotics for approximately 120 d. Calves were assigned to 1 of 5 treatments: a control with no antibiotics, 11 mg/kg of chlortetracycline, 44 mg/kg of chlortetracycline, 44 mg/kg of chlortetracycline plus 44 mg/kg of sulfamethazine, and 11 mg/ kg of tylosin phosphate. A combination of GLC and silver-ion HPLC methods was used to analyze the fatty acid composition of brisket adipose tissue, with emphasis on trans-18:1 and CLA isomers. The inclusion of nonionophore antibiotics in the diet had little effect on the fatty acid composition, except that feeding either 44 mg/kg of chlortetracycline or 11 mg/kg of tylosin caused small increases in 9c-14:1 and 16:0 relative to the control (0.26 and 0.9 g/100 g of total fatty acids, respectively). Likewise, profiles of trans-18:1 and CLA isomers were unchanged by antibiotics, but across treatments the predominant trans-18:1 isomer was 10t-18:1 (where t = trans; 3.22%) at 3 times the concentration of the second most abundant isomer (11t-18:1; vaccenic acid, 1.05%). Rumenic acid (9c,11t-18:2, where c = cis) was the major CLA isomer at 61% of total CLA, followed by 7t,9c-18:2 at 9%. Because no other effects on fatty acid composition were evident, data for trans-18:1 and CLA were pooled across treatments to investigate possible relationships among rumen PUFA metabolites. The total trans-18:1 content in brisket adipose tissue was positively correlated with 10t-18:1, but not with 11t-18:1, whereas the total CLA was positively correlated with 9c,11t-18:2, but not with 7t,9c-18:2. The 7t,9c-18:2 was, however, positively correlated with 10t-18:1 and 6t/7t/8t-18:1 but was negatively correlated with rumenic acid. These metabolic interrelationships suggest the presence of bacterial populations with distinct pathways for PUFA biohydrogenation in which either 10t-18:1 or 11t-18:1 predominate. Overall, the nonionophore antibiotics tested did not appreciably change adipose tissue composition and consequently could not be used to improve the trans-18:1 or CLA profile (i.e., increase vaccenic and rumenic acids at the expense of 10t-18:1).

Evaluation of Beef Cattle Operations Utilizing Different Seasons of Calving, Weaning Strategies, Postweaning Management, and Retained Ownership

Data from a 3-yr study in Montana were utilized to evaluate impacts of season of calving, weaning strategy, and retained ownership of steer calves on enterprise profitability. Calving seasons were late winter (LW), early spring (ES), or late spring (LS). Each season had 2 weaning times: 190 (LW190, ES190) or 240 (LW240, ES240) d for LW and ES, and 140 (LS140) or 190 (LS190) d for LS. Backgrounding options included shipping steers to Oklahoma (OK1), or backgrounding in Montana to a constant age (MT2) or weight (MT3). Steers from OK1 and MT2 were finished in Oklahoma in confinement or via self-feeders on pasture and harvested in Texas. Steers in MT3 were finished in Montana in confinement and harvested in Colorado. Performance of each system was modeled based on actual animal performance, market prices, and variable input costs. When calves were sold at weaning, gross margins per cow were greatest for LS190 (P < 0.05) and lowest for LW240. During backgrounding, costs of gain were similar among cow-calf systems, and gross margins per steer were greatest for LS140 (P < 0.05), but not different among backgrounding systems. During finishing, costs of gain were greatest for steers from MT2 due to transportation costs to Oklahoma (P < 0.05), and gross margin per steer favored MT3 (P < 0.05). Gross margin for a ranch with a fixed land base did not differ among systems if calves were sold at weaning, but was greatest for LS systems after backgrounding or finishing (P < 0.05).

Effects of commingling beef calves from different sources and weaning protocols during a forty-two-day receiving period on performance and bovine respiratory disease1,2

The study objective was to determine health and performance of ranch calves from different preconditioning strategies during a 42-d receiving period when commingled with calves of unknown health histories from multiple sources. Steer calves from a single source ranch (RANCH) were weaned and immediately shipped to a feedlot (WEAN, initial BW = 247 +/- 29 kg); weaned on the ranch for 45 d before shipping, but did not receive any vaccinations (WEAN45, initial BW = 231 +/- 26 kg); or weaned, vaccinated with modified live viral vaccine, and held on the ranch for 45 d before shipping (WEANVAC45, initial BW = 274 +/- 21 kg). Multiple-source steers were purchased through auction markets (MARKET, initial BW = 238 +/- 13 kg), and upon receiving, a portion of ranch-origin steers from each weaning group was commingled with a portion of MARKET cattle (COMM). The experimental design was completely randomized with a 2 x 3 +1 factorial arrangement of treatments. Factors were RANCH vs. COMM and weaning management (WEAN vs. WEAN45 vs. WEANVAC45) as the factors; MARKET cattle served as the control. Calves of WEAN, WEAN45, and MARKET were vaccinated on arrival at the feedlot. Ranch-origin calves tended (P = 0.06) to have greater ADG than COMM or MARKET calves, although ADG was not affected (P = 0.46) by weaning management. Across the 42-d receiving period, DMI was not affected (P = 0.85) by cattle origin. However, MARKET, WEAN45, and WEANVAC45 calves consumed more (P < 0.001) DM than WEAN calves. Gain efficiency was not affected (P > or = 0.11) by treatment. Ranch-origin calves were less (P < 0.001) likely to be treated for bovine respiratory disease than MARKET calves; COMM calves were intermediate. Calves that were retained on the ranch after weaning (WEAN45 and WEANVAC45) were also less likely to be treated (P = 0.001) than MARKET or WEAN calves. As expected, differences in morbidity related to differences in health costs. Calves of WEAN45 and WEANVAC45 had less (P < 0.001) health costs than MARKET and WEAN calves. On arrival, serum haptoglobin concentrations were greater (P < 0.001) in MARKET and WEAN compared with WEAN45 and WEANVAC45 calves. Calves from a single source that are retained on the ranch for 45 d after weaning exhibit less morbidity and less health costs during the receiving period at the feedyard than when cattle are commingled or trucked to the feedyard immediately after weaning.

Influence of slice baling on feeding value of alfalfa hay in receiving and finishing diets for feedlot cattle1

Three studies were conducted to evaluate the feeding value of slice alfalfa hay in feedlot diets. In Exp. 1, 108 steer calves (183.1 +/- 1.2 kg initial BW; 6 pens/treatment) were used in a completely randomized design to evaluate the effect of baling method on performance and morbidity of newly received calves. The study lasted 28 d. Treatments consisted of a 65% concentrate receiving diet containing 1) ground or 2) slice alfalfa hay. Steer calves were fed daily at 0800 h. Animals also received long-stem sudangrass hay the first 7 d. Steers were weighed on d 0, 16, and 28. Feed, sudangrass hay, or feed plus sudangrass hay intakes were not affected (P > 0.25) by treatment. Conversely, ADG from d 0 to 16 was greater (P < 0.001) for slice than ground (1.27 vs. 0.81 +/- 0.067 kg/d, respectively) and from d 0 to 28 (1.23 vs. 0.91 +/- 0.042 kg/d, respectively). In addition, G:F was greater (P < 0.001) for slice than ground hay from d 0 to 16 (0.39 vs. 0.25 +/- 0.021), and from d 0 to 28 (0.31 vs. 0.24 +/- 0.013 for slice and ground, respectively). Moreover, morbidity (40.5 +/- 3.9%; P = 0.20) and retreatment rates (30.7 +/- 7.5%; P = 0.14) were similar for slice and ground. In Exp. 2, 176 crossbred steers (393.9 +/- 10.8 kg initial BW) were used in an 84-d feeding experiment (4 pens/treatment) in a randomized complete block experimental design with a 2 x 2 factorial arrangement of treatments to evaluate effects of alfalfa baling method (ground or slice) and forage level (8 or 14%) on growth performance. Experimental diets were based on steam-flaked corn. Daily BW gain was greater (P = 0.10) for steers consuming ground compared with the slice hay diet. A baling method x forage level interaction (P = 0.07) was observed for DMI. Baling method did not (P = 0.98) influence DMI with 8% roughage level. But with 14% roughage, DMI was greater (P = 0.02) for steers consuming ground hay than the slice diet. The G:F ratio was affected (P = 0.03) only by forage level (0.194 vs. 0.182 +/- 0.003 for 8 and 14% roughage, respectively). In Exp. 3, 4 ruminally cannulated mixed-breed steers were used in a 4 x 4 Latin square design to evaluate effects on digestive function. No baling method effects (P >or= 0.16) were detected for DM, OM, CP, or NDF intakes or DM, OM, and NDF total tract digestibility. Digestibility of NDF and OM were greater (P <or= 0.08) for diets which contained 14% forage compared with diets that contained 8% forage. Slice baling improved alfalfa hay feeding value for feedlot receiving cattle. However, no major effects of slice baling alfalfa on finishing performance and digestion were observed.

Performance, Carcass Characteristics, and Economic Analysis of Calf-Fed and Wheat Pasture Yearling Systems in the Southern Great Plains

AbstractModerate-framed Angus steers from a single cow herd were utilized in a 2-yr study that evaluated performance, carcass traits, and production economics of calf-fed vs. yearling systems. After a brief preconditioning period, weaned steer calves were placed on a high concentrate finishing diet (CF; n = 63) or grazed wheat pasture 164 d before feedlot entry (YF; n = 62). Resulting feedlot entry weight and days on feed were 228kg and 169 d, respectively, for CF and 445kg and 88 d, respectively, for YF. Final BW for YF was 87kg heavier than CF (P < 0.01). For YF, ADG and DMI was greater and G:F was less than CF steers (P < 0.05). Hot carcass weight was 55kg greater and LM area was 8cm2 larger for YF compared with CF steers (P < 0.01). Dressing percentage was not different between systems (P = 0.90). System did not affect 12th-rib fat, USDA YG, or marbling score (P > 0.27). Profitability tended (P = 0.09) to favor the CF over the YF system, although breakeven selling price was greater (P < 0.01) for CF vs. YF. Live and carcass price was greater (P = 0.02) for the CF system. Net profit for CF and YF was not different (P > 0.10) when quality or yield grid markets were applied. Inclusion of a long-term winter wheat grazing period increased hot carcass weight by 17% with no detrimental effects on carcass characteristics.

Intake and digestion of wheat forage by stocker calves and lambs

Because wheat forage contains high concentrations of N, NPN, digestible DM, and water, beef cattle and sheep require an adaptation period before positive BW are seen. The objective of the present experiment was to determine the impact of length of exposure of lambs and steers to wheat forage on BW gains, N retention, and forage digestibility. Sixteen steer calves (average BW = 210 +/- 12 kg) and 20 wether lambs (average BW = 31.5 +/- 2.0 kg) were randomly assigned to 1 of 2 treatment groups. Group 1 grazed a wheat pasture for 120 d during the winter, whereas group 2 was wintered on dormant warm-season grass pastures plus warm-season grass hay and plant-based protein supplements. In the spring (April 5), all lambs and steers grazed wheat pasture for 14 d and were then housed in metabolism stalls and fed freshly harvested wheat forage to determine forage digestibility and N metabolism. Data were analyzed for lambs and steers separately as a completely randomized design, using the individual animal as the experimental unit. Lambs and steers grazing wheat pasture for the first time in the spring had less ADG during the first 14 d than lambs (80 vs. 270 g, respectively; P = 0.01) and steers (1.06 vs. 1.83 kg, respectively; P = 0.09) that had grazed wheat pastures all winter. Digestibility of DM, NDF, and ADF fractions and N metabolism of freshly harvested wheat forage by lambs and steers were not different (P > 0.10) between the 2 treatment groups. Less ADG during the first 14 d of wheat pasture grazing is most likely the result of less DMI by nonadapted animals and is not due to diet digestibility or N metabolism.

Preweaning Performance of Calves from Bonsmara, Brangus, Charolais, Gelbvieh, Hereford, and Romosinuano Sires Bred to Brangus Cows Managed on Native Rangeland or Improved Forages ,

AbstractPreweaning data on 511 spring-born calves from 187 Brangus cows and 129 Bonsmara, Brangus, Charolais, Gelbvieh, Hereford, and Romosinuano sires were measured over a 4-yr period to determine sire breed, sex, and age of dam differences under 2 preweaning forage environments: 1) native tallgrass rangeland (native) or 2) improved warm-season forages (improved). Sire breed differences in birth weight varied across forage (P < 0.05) with Romosinuano-sired calves on improved forages ranked intermediate in birth weight compared with other sire breeds but lightest on native forages. Calves from Charolais and Gelbvieh tended to be heavier at 205 d of age than calves from other sire breeds on improved forages (P < 0.05, except Gelbvieh vs. Hereford, P < 0.12) whereas on native forages, Bonsmara-, Charolais-, and Gelbvieh-sired calves were similar but were heavier than Brangus- and Romosi-nuano-sired calves (P < 0.10). Steer calves were heavier than heifer calves on improved forages (P < 0.01) but not on native forages. Sire breed differences were not significant on improved forages for weaning condition score. On native forage, weaning condition scores were greater for calves sired by Bonsmara and Hereford (P < 0.05) compared with Brangus-, Charolais-, and Gelbvieh-sired calves, and Charolais-sired calves were lesser than other sire breeds (P < 0.05). These results provide evidence of nonadditive associations between preweaning forage systems, sire breed of calves, age of dam, and sex of calf in preweaning traits. Consideration should be given to appropriate combinations of these effects in development of efficient cow-calf production systems.

Effect of tilmicosin alone or in combination with Mannheimia haemolytica toxoid administered at initial feedlot processing on morbidity and mortality of high-risk calves.

A total of 3,996 high-risk steer calves were used to compare effects of metaphylactic treatment with tilmicosin (TIL) alone or in combination with an adjuvanted Mannheimia haemolytica toxoid (MHT) at feedyard arrival on health parameters and economic return in a commercial feedlot setting. Steers receiving TIL-MHT at processing had 17% fewer first time treatments for BRD (P=0.0002) than calves in the TIL group, and a 19% lower relapse rate (P=0.003). TIL-MHT calves had 22% less mortality (P=0.03) than calves in the TIL group. Calves receiving TIL-MHT had $1.37 (P&lt;0.0001) and $13.14/head (P=0.03) lower therapy and mortality costs, respectively, than calves in the TIL group. In total, combined processing, therapy, railer (culls) and mortality costs for TIL-MHT calves were $14.77 lower (P=0.01) than TIL group calves.

Effects of on-arrival versus delayed modified live virus vaccination on health, performance, and serum infectious bovine rhinotracheitis titers of newly received beef calves1

Stress commonly associated with weaning, marketing, and shipment of feeder cattle can temporarily compromise immune function, thereby reducing the effective response to vaccination intended to control bovine respiratory disease (BRD). Two vaccination timing treatments were used to evaluate the effect of timing of a multivalent modified live virus (MLV) BRD vaccine on health, performance, and infectious bovine rhinotracheitis (IBR) antibody titers of newly received stocker cattle. Crossbred bull and steer calves (n = 528) were weighed (197 +/- 2.4 kg) and randomly assigned to MLV vaccination treatment: 1) MLV vaccination upon arrival (AMLV), or 2) delayed (14 d) MLV vaccination (DMLV). All cattle were processed similarly according to routine procedures, with the exception of the initial MLV vaccination timing. Subsequently, BW were recorded on d 14, 28, and 42. Blood samples were collected on d 0, 14, 28, and 42 to determine serum IBR titers, and comparisons were made between treatments on a receiving-day basis and an equivalent postvaccination day basis. Daily BW gains were greater (P < or = 0.05) for DMLV calves from d 0 to 14 (1.16 vs. 0.88 +/- 0.22 kg/d) and from d 0 to 42 (0.75 vs. 0.65 +/- 0.09 kg/d). Days to first treatment, total treatment cost, percentage death loss, and pasture ADG after the 42-d receiving period did not differ (P > or = 0.15). Morbidity rates for BRD were high for both AMLV and DMLV (71.5 and 63.5%, respectively) and did not differ (P = 0.12). Positive IBR titer seroconversion was greater (P < or = 0.03) for DMLV calves on d 42 of the study, and for the 28- and 42-d equivalent postvaccination basis. Delaying vaccination by 14 d may increase ADG during the receiving period compared with AMLV, and seroconversion to IBR was greater in DMLV calves, indicating a possible improvement in acquired immune response when MLV vaccination is delayed.

Influence of starch and casein administered postruminally on small intestinal sodium-glucose cotransport activity and expression

Twenty-four Holstein steer calves (88 ± 3kg) with abomasal catheters were randomly assigned within blocks to one of four treatments. The treatments consisted of four abomasal infusions: water (control), 4 g/kg BW.d-1 of partially hydrolyzed starch (SH), 0.6 g/kg BW.d-1 of casein, and a mix of SH + casein. The small intestine was collected and five equidistan, 1m sites were identified (duodenum, jejunum 1, jejunum 2 jejunum 3 and ileum). Maltase specific activity in mucosal homogenate and brush border membrane vesicles, SGLT1 protein abundance, and sodium-dependent glucose uptake in brush border membrane vesicles did not differ between the calves receiving different abomasal infusion treatments. However, maltase specific activity in homogenates and brush border membrane vesicles increased four-fold from the duodenum to the first jejunal site before declining steadily towards the ileum (p=0.0145 p=0.0020, respectively). The SGLT1 abundance differed by intestinal sampling site (p=0.0162). These data indicated that cattle might not have the ability to alter the capacity for glucose uptake when challenged with different substrates and that the regulation of SGLT1 expression could differ between bovine and other species.

Production and Economic Comparisons of Two Calving Dates for Beef Cows in the Nebraska Sandhills

<h2>ABSTRACT</h2> Calving date for 120 cows in the Nebraska Sandhills was changed from the traditional calving season beginning March 15 (d 75) to one beginning June 15 (d 167) to match increased nutrient needs for lactating cows to immature grazed forages that are high in protein and energy. The hypotheses being tested were that 1) less hay and purchased feeds would be required, 2) production costs would be reduced, and 3) net returns would be greater for June-calving cows compared with their March-calving counterparts. All steer calves from 75 March-calving cows were moved to a feedlot within 60 d of weaning (March calf-feds). Half the steer calves from the 120 June-calving herd were moved within 60 d of weaning to a feedlot to be finished (June calf-feds) and the other half were moved to a feedlot in September after summer grazing of Sandhills rangeland (June yearlings). Half of the June-calving cows were bred on subirrigated regrowth (Meadow) and half on upland range. Data on 4 consecutive calf crops were collected through harvest with an additional year collected to feedlot placement. Results showed that fed hay was reduced from 1.79 to 0.10 metric tons per cow annually for the June-calving system. Cost and return analyses were conducted by production phases on steer calves. Production costs for both June-calving groups were less and net returns higher when compared with the March-calved group. The highest net return for a calf group was for the June yearlings from cows bred on subirrigated regrowth.

Phase Feeding Strategies To Meet Metabolizable Amino Acid Requirements of Calf-Fed Holstein Steers

ABSTRACT One hundred eight Holstein steer calves (114 ± 8 kg) were used to evaluate effects of phase feeding metabolizable amino acids (MAA) on growth performance and carcass characteristics. Three feeding strategies were evaluated: 1) control, single-phase feeding (steers were fed a single urea-based growing-finishing diet that meets the average MAA requirements for the overall feeding period); 2) 2-phase feeding (steers were fed a diet formulated to meet the average MAA requirements for the first 112 d on feed, and thereafter finished on the control urea-based diet); and 3) 3-phase feeding (2 diets were formulated to meet average MAA requirements during the first and second 56-d feedlot feeding periods, and thereafter cattle were finished on the control urea-based diet). Two-phase feeding and 3-phase feeding management strategies produced similar (P > 0.20) growth performance. Multiple-phase feeding increased ADG (18%, P 0.20) on growth performance; however, multiple-phase feeding increased overall (351-d) ADG (6.3%, P 0.20) of 3-phase vs. 2-phase feeding strategies on carcass characteristics. Multiple-phase feeding increased hot carcass weight (5.2%, P g was similar (96%) to that expected for the 2- and 3-phase programs during the first 112 d, but was only 83% of expected for the single-phase program. It was concluded that a 2-phase feeding program was needed to improve overall ADG, G:F, and energetic efficiency of calf-fed (placed in the feedlot as lightweight calf) Holstein steers compared with a conventional single-phase system. At a minimum, a 2-phase system would need to separately consider MAA requirements from feedlot placement to 280 kg BW (phase 1) and from 280 kg BW to harvest (phase 2). Methionine, Lys, and His appear to be the first limiting amino acids during the first feeding phase. During the second phase (280 kg to harvest), supply of all MAA acids will exceed requirements, even where urea is the sole source of supplemental N. Maximizing growth rate during the first feeding phase may enhance carcass dressing percent and LM area.

Genetic effects on acute phase protein response to the stresses of weaning and transportation in beef calves1,2

The objective herein was to estimate heterosis and breed effects in purebred and crossbred Romosinuano, Brahman, and Angus calves on acute phase protein response to weaning and transportation. Calves (n = 1,032) were weaned in September of 2002, 2003, and 2004 at approximately 7 mo of age. Approximately 28 d after weaning, steer calves (n = 482) were transported 1,800 km (20 h) to Oklahoma. Concentrations of 3 acute phase proteins (ceruloplasmin, fibrinogen, and haptoglobin) were measured in blood samples. Calves (steers and heifers) were sampled at weaning, and 24 and 72 h postweaning. For separate analyses, steers sent to Oklahoma were sampled before shipment, upon arrival, and 24 and 72 h after arrival. Combinations of the following fixed effects were investigated: sire breed, dam breed, sampling time, birth location, calf sex (weaning only), year, cow age, and interactions. Effects of special interest were sire breed x dam breed as an indication of breed group of calf, and the interaction of sire and dam breeds with sampling time. Weaning age and BW were investigated as linear and quadratic covariates. Sire of calf within sire breed was a random term. The correlation structure of repeated measures was determined by comparison of information criterion values for different structures within each analysis. In general, plasma acute phase protein concentrations in weaned calves increased with sampling time. Concentrations in the transported steers increased through sampling at 24 h after arrival, and were lower at 72 h. Significant estimates of heterosis were detected for Brahman-Angus haptoglobin concentrations at weaning (0.38 +/- 0.14 mg/dL x 100; 44%), and for Romosinuano-Angus fibrinogen concentrations at weaning (11.4 +/- 5.5 mg/dL; 10%) and in transported steers (22.5 +/- 8.4 mg/dL; 20%). The direct effect of Romosinuano was to increase (P <0.004) ceruloplasmin concentrations of weaned calves (4.1 +/- 0.9 mg/dL) and of transported steers (3.9 +/- 1.3 mg/dL). The direct effect of Angus was to lower ceruloplasmin concentrations in weaned calves (-3.9 +/- 1.2; P = 0.001). Significant maternal effects were detected at weaning for ceruloplasmin concentrations in Romosinuano (-1.4 +/- 0.5 mg/ dL) and Angus (1.6 +/- 0.7 mg/dL) and fibrinogen concentrations in Brahman calves (-17.7 +/- 8.8 mg/dL). These data imply that acute phase protein concentrations in response to weaning and transportation are impacted by cattle breed.

Field study comparing fecal egg count reduction, weight gain and product safety in stocker cattle treated with either moxidectin or ivermectin with clorsulon

This study was conducted to assess effectiveness, safety and benefit of injectable moxidectin compared to an injectable ivermectin-clorsulon combination. A total 2,022 stocker calves maintained on 11 Arkansas and Missouri cattle farms were randomly and evenly allocated on each farm into either the moxidectin (MXD) or ivermectin-clorsulon (IC) group. No negative controls were utilized in the study. All treatments were administered on a unique day 0 for each farm. Herd sizes ranged from 54 to 544. Naturally infected mixed breed bull, steer or heifer calves, weighing from 241 to 810 lb (110 to 368 kg) on day 0, were used in the study. On days 0, 50 (approx) and 100 (approx), each animal was weighed, and fecal samples were obtained from 20% of the animals (same animals on each sample day) for determination of fecal nematode egg counts and coproculture larvae identification. Both products were easily administered and no adverse effects were noted following administration of either drug. Weight gain from day 0 did not vary significantly between treatment groups at either of the post-treatment sampling dates. In addition, sex by treatment interaction was not significant (P&lt;0.05), as analyzed on those farms that had both male and female cattle in the study population. On day 0, no significant differences were found between treatment groups for strongyle eggs per gram of feces (EPG) counts or coproculture larvae percentages. For days 50 and 100, EPG counts for MXD-treated calves were significantly lower than those for IC-treated calves (P&lt;0.05). Day 0 coproculture data indicated that the primary nematode parasites contributing to the fecal egg counts were Cooperia, Haemonchus and Ostertagia. On days 50 and 100, MXD-treated animal coprocultures yielded higher larvae percentages of Cooperia than did the IC-treated animal coprocultures (P&lt;0.05), as well as significantly lower Ostertagia and Haemonchus larvae percentages. Egg count and coproculture results suggest that both parasiticides were most limited in their ability to control Cooperia, but greater post-treatment egg production by Cooperia, Ostertagia and Haemonchus occurred in calves treated with IC compared to those in the MXD group.

Dietary Phosphorus Requirement of Holstein Steers During Early Growing Period

López, J.R., Montaño Gómez, M.F., Jorquera, A.P., Chavira, J.S. and Zinn, R.A. 2007. Dietary phosphorus requirement of Holstein steers during early growing period. J. Appl. Anim. Res., 31: 113–115. Ninety-six Holstein steer calves (120.7±5.3 kg) were used to evaluate the influence of dietary phosphorus level (0.27, 0.31, 0.35 and 0.39%, DMB) on growth-performance during the initial 105 d on feed. Dicalcium phosphate was the source of supplemental phosphorus. All diets were formulated to contain 0.85% calcium (DMB). Dietary phosphorus level did not affect (P>.10) DMI or body size measurements. However, increasing dietary phosphorus level increased ADG (linear component, P<.05), gain efficiency (quadratic component, P<.05) and dietary NE (quadratic component, P<.05). It is concluded that during the initial growing period ADG, gain efficiency and dietary NE are optimal at a dietary phosphorus level of 0.35%, 15% lower than current NRC recommendations.