J. P. Schoonmaker
F. L. Fluharty
T. B. Turner
S. J. Moeller
S.
C. Loerch1
The Ohio State University
Department of Animal
Science
1 For more information contact at: The Ohio State University, Ohio Agricultural Research and Development Center, 1680 Madison Ave., Wooster, OH 44691; 330-263-3903.
AbstractSixty-seven Angus x Simmental crossbred steers (initial body weight (BW) 341.3 ± 13.7 lbs.) were used in a 2x2 factorial experiment to determine the effects of weaning age and implant regimen on growth and performance. Steers were either early-weaned (EW) at an average age of 113 days or normal-weaned (NW) at an average age of 204 days, and allotted by weight to an aggressive (A) or non-aggressive (NA) implant regimen. EWA and NWA steers were implanted with SynovexC at an average age of 163 days, RevalorS at an average age of 204 days and 295 days if BW was < 1,050 lbs. EWNA and NWNA steers were implanted with SynovexS at an average age of 204 days, and 295 days if BW was < 1,050 lbs. Steers were individually penned and fed an 85% concentrate, 12.4% crude protein (CP) finishing diet. Steers were slaughtered when they reached 1,205 lbs. Days on feed were greater (P < 0.01) for EW vs. NW steers (241 vs. 173 days, respectively) and tended to be lower (P < 0.12) for A vs. NA (201 vs. 213 days, respectively). Overall average daily gain (ADG) was higher (P < 0.0001) for EW vs. NW steers (3.64 vs. 3.26 lbs./days, respectively), and for A vs. NA (3.55 vs. 3.35 lbs./day, respectively; P < 0.03). Daily postweaning dry matter intake (DMI) was lower for EW vs. NW steers, but total postweaning DMI was higher (P < 0.0001) for EW vs. NW steers (3,965.0 vs. 3,210.3 lbs., respectively). Gain/feed was improved (P < 0.06) for both EW vs. NW steers (0.219 vs. 0.209 lbs./lbs., respectively) and A vs. NA (0.219 vs. 0.209 lbs./lbs., respectively). Final age was lower (P < 0.01) for EW vs. NW steers (353 vs. 378 days, respectively). Percentage of steers not reaching 1,150 lbs. was lower (P < 0.02) for A vs. NA (0.0 vs. 12.5%, respectively). Placing early-weaned calves on an aggressive implant regimen is a viable management option. Early-weaned steers convert feed more efficiently and gain faster from birth until slaughter than do NW steers.
Mid- to late-summer pasture growth tends to slow because of the hot, dry weather in many parts of the United States. Forage yield and quality decline, and as a result, cow body condition and milk production can decline. Spring born calves therefore experience decreased gains when their growth potential is high. By eliminating the demands of a suckling calf, and the nutrient requirements of a mid- to late-lactation cow, early weaning can increase cow condition and the carrying capacity of the land. Therefore, early weaning may be an economically advantageous solution in cases of limited land and feed supplies, and may be a way to market cattle quickly through retained ownership.
Early weaning prior to 150 days (Myers et al., 1996), 120 days (Williams et al., 1975; Richardson et al., 1978; Peterson et al., 1987), or 70 days, (Lusby et al., 1981; Neville and McCormick, 1981) has improved cow weight gain from early weaning to normal weaning. Peterson et al. (1987) reported that early-weaned cow-calf pairs were 43% more efficient in converting total digestible nutrients into gain than were normal-weaned cow-calf pairs.
Anabolic implants are used to improve the growth rate, performance, feed efficiency, and leanness of cattle, primarily through an increased rate of protein deposition. An aggressive implant regimen could complement early weaning and allow for rapid and efficient growth while increasing leanness. The objectives of this experiment were to determine the effects of weaning age and implant regimen on performance.
Sixty-seven Angus x Simmental crossbred steers were used to determine the effects of weaning age and implant regimen on growth and performance. Steers were either early-weaned at an average age of 113 days (EW) or normal-weaned at an average age of 204 days (NW), and allotted by weight to an aggressive (A) or nonaggressive (NA) implant regimen. Early-weaned steers were transported to The Ohio State University's Ohio Agricultural Research and Development Center (OARDC) feedlot in Wooster, Ohio, on July 2, 1996. Normal-weaned steers remained with their dams throughout the summer until October 1, 1996, when they were transported to the OARDC feedlot. Period 1 began July 2, lasted 91 days (average age of 113 days), and ended October 1 (average age of 204 days). Period 2 began October 1 (average age of 204 days) and ended when steers were slaughtered.
EW and NW steers on the aggressive implant regimen were implanted with SynovexC (provided courtesy of Fort Dodge Animal Health, Overland Park, KS) at an average age of 163 days, RevalorS (provided courtesy of Hoechst-Roussel Agri. Vet. Co., Overland Park, KS) at an average age of 204 days, and again at 295 days if body weight (BW) was < 1,050 lbs. EW and NW steers on the nonaggressive implant regimen were implanted with SynovexS at an average age of 204 days and again at 295 days if BW was < 1,050 lbs. Previous research suggests that if the final TBA-containing implant is administered more than once, or too near the date of slaughter, reduced marbling scores and decreased tenderness may result (Foutz et al., 1990), therefore a maximum body weight of 1,050 lbs. was used as a cut off to determine if steers should be implanted at 295 days of age.
All steers were penned individually in a totally enclosed feedlot barn, and fed an 85% concentrate, 16.4% crude protein (CP) receiving diet (Table 1) for the first 14 days. An 85% concentrate, 12.4% CP finishing diet (Table 1) was fed for the remainder of the trial. Diets were formulated to provide 18% and 14% for receiving and finishing diets respectively, but due to lower than normal protein values for corn and corn silage (7.5% and 6.0% vs. 8.75% and 8.0% protein respectively), the diet was actually formulated too low for protein. Steers were fed once daily, beginning at 0800 hours, and feed refusals were recorded daily for each steer.
| Table 1. Diet Composition | ||
|---|---|---|
| Item | Receiving | Finishing |
| % DM basis | ||
| Ingredient | ||
| Shelled corn | 60.000 | 70.000 |
| Corn Silage | 15.000 | 15.000 |
| Ground corn | 0.483 | 0.483 |
| Soybean meal | 20.500 | 10.500 |
| Urea | 0.500 | 0.500 |
| Limestone | 1.600 | 1.600 |
| Dicalcium phosphate | 0.750 | 0.750 |
| Trace mineral salta | 0.500 | 0.500 |
| Vitamin A, 30,000 IU/g | 0.010 | 0.010 |
| Vitamin D, 3,000 IU/g | 0.010 | 0.010 |
| Vitamin E, 44 IU/g | 0.030 | 0.030 |
| Selenium, 201 mg/kg | 0.050 | 0.050 |
| Rumensin, 176 g/kg | 0.017 | 0.017 |
| Potassium chloride | 0.150 | 0.150 |
| Dynamateb | 0.400 | 0.400 |
| Calculated composition | ||
| Calcium,% | 0.82 | 0.79 |
| Phosphorus,% | 0.54 | 0.50 |
| Potassium,% | 0.96 | 0.78 |
| NEm, Mcal/kg | 2.02 | 2.04 |
| NEg, Mcal/kg | 1.38 | 1.39 |
| Analyzed composition | ||
| Crude protein,% | 16.40 | 12.39 |
| Neutral Detergent Fiber,% | 17.85 | 16.89 |
| Acid Detergent Fiber,% | 8.39 | 7.24 |
| a Contained > 93% NaCl, 0.35% Zn, 0.28% Mn, 0.175%
Fe, 0.035% Cu, 0.007% I, and 0.007% Co. b Magnesium sulfate and potassium sulfate. Contained 22% S, 18% K, 11% Mg (International Minerals and Chemical, Terre Haute, IN). | ||
Interim weights were determined every 28 days, weighing each animal prior to feeding. Initial and final weights were determined by averaging animal weights prior to feeding on two consecutive days. Average daily gain (ADG), dry matter intake (DMI), and feed efficiency (gain/feed) were determined for each 28 day period, as well as for the entire trial. Feed samples were collected every seven days throughout the trial and analyzed for dry matter according to the procedures of Goering and Van Soest (1970). Monthly composites of feed were analyzed for nitrogen (N) content using a LECO 2000 nitrogen analyzer (LECO Corporation, St. Joseph, MI). Neutral detergent fiber (NDF) and acid detergent fiber (ADF) were determined according to the procedures of Van Soest et al. (1991).
Steers were removed from the trial on an individual basis when they reached a predetermined terminal body weight (1,205 lbs.). Steers were taken to a common terminal weight because carcass fat percentage has been shown to be directly related to carcass weight (Berg and Butterfield, 1967; Waldman et al., 1971; Ferrell et al., 1978). Research protocols regarding animal care followed guidelines recommended in the Guide for the Care and Use of Agricultural Animals in Agricultural Research and Teaching (Consortium, 1988).
Data were analyzed using the GLM procedures of SAS (SAS, 1988) for a completely randomized 2 x 2 factorial experiment. The model included effects due to weaning status, implant regimen, and the weaning status by implant regimen interaction. The animal was served as the experimental unit.
Due to poor performance, 3.1% of EW steers and 9.4% of NW steers did not achieve the target minimum kill weight of 1,150 lbs (Table 2). All of these steers were in the NA implant treatment and were removed from the statistical analysis because they were gaining less than 1.0 lb./day for a prolonged period of time. As a result, they would not have reached the predetermined kill weight of 1,205 lbs. in a reasonable amount of time. Percentage of cattle removed due to implant regimen was different (P < 0.04), however, percentage of cattle removed due to weaning status was not different (P > 0.6).
| Table 2. Effects of Age at Weaning and Implant Regimen on Gain and Hip Height. | ||||||||
|---|---|---|---|---|---|---|---|---|
| Item | Age at weaning | Implant regimen | P - value | |||||
| EW 113 Days |
NW 205 Days |
Aggressive | Non- Aggressive |
SEM | Wean | Implant | Wean x Implant | |
| No. of animals | 33 | 29 | 34 | 28 | ||||
| Initial age, day | 112.0 | 113.3 | 113.9 | 111.4 | 3.2 | 0.75 | 0.57 | 0.29 |
| Final age, day | 352.7 | 378.3 | 360.6 | 370.5 | 5.8 | 0.01 | 0.21 | 0.81 |
| Days on feed | ||||||||
| Period 1 (d 113-204) | 92.0 | 0.0 | ||||||
| Period 2 (d 204-slaughter) | 148.7 | 73.0 | 154.7 | 167.1 | 5.7 | 0.01 | 0.11 | 0.73 |
| Overall (d 113-slaughter) | 240.7 | 173.0 | 200.7 | 213.1 | 5.7 | 0.01 | 0.11 | 0.73 |
| Body weight, lb. | ||||||||
| Initial | 338.9 | 344.9 | 340.0 | 343.8 | 10.4 | 0.67 | 0.79 | 0.60 |
| 204 day | 665.0 | 558.1 | 620.9 | 602.2 | 13.9 | 0.01 | 0.32 | 0.95 |
| At reimplantation | 1,020.3 | 918.8 | 984.5 | 954.8 | 17.4 | 0.01 | 0.21 | 0.74 |
| Final | 1,203.1 | 1,203.9 | 1,205.7 | 1,201.3 | 3.7 | 0.86 | 0.39 | 0.75 |
| % not reimplanted | 29.4 | 6.3 | 25.7 | 10.0 | 7.2 | 0.02 | 0.11 | 0.74 |
| % not reaching 1150 lb. | 3.1 | 9.4 | 0.0 | 12.5 | 4.1 | 0.28 | 0.03 | 0.28 |
| Average daily gain, lb./day | ||||||||
| Period 1 (d 113-204) | 3.55 | 2.32 | 3.04 | 2.80 | 0.07 | 0.01 | 0.01 | 0.31 |
| Period 2 (d 204-slaughter) | 3.70 | 3.90 | 3.90 | 3.70 | 0.09 | 0.12 | 0.12 | 0.71 |
| Overall (d 113-slaughter) | 3.64 | 3.26 | 3.55 | 3.35 | 0.07 | 0.01 | 0.02 | 0.36 |
| Post-wean | 3.64 | 3.90 | 3.88 | 3.66 | 0.09 | 0.03 | 0.06 | 0.57 |
| Final wt./day of age, lb. | 3.42 | 3.20 | 3.37 | 3.26 | 0.07 | 0.01 | 0.17 | 0.99 |
| Gain/day of age, lb. | 3.20 | 2.98 | 3.15 | 3.02 | 0.04 | 0.00 | 0.12 | 0.88 |
| Hip height, in. | ||||||||
| 204 days | 44.3 | 44.1 | 44.6 | 43.8 | 0.4 | 0.61 | 0.10 | 0.82 |
| Final | 51.3 | 51.2 | 51.1 | 51.4 | 0.3 | 0.65 | 0.48 | 0.63 |
| Change | 7.0 | 7.1 | 6.5 | 7.6 | 0.2 | 0.78 | 0.01 | 0.83 |
Early-weaned steers were in the feedlot 68 days longer (241 vs. 173; P < 0.0001) than NW steers, however, EW steers were 25 days younger (353 vs. 378; P < 0.002) at slaughter. Aggressive implant steers tended (P < 0.12) to be in the feedlot for a shorter period of time (201 vs. 213) than NA steers, but were not younger (P > 0.21).
EW steers gained faster than NW steers (3.55 vs. 2.32 lbs/day; P < 0.0001), during the first period, however, during the second period, NW steers tended to gain faster than EW steers (3.90 vs. 3.70 lbs./day; P < 0.12). Increased gains occurred because NW steers experienced compensatory growth upon entering the feedlot. The compensatory growth, however, could not overcome the rapid growth of EW steers during the first period of the trial. Early-weaned steers, therefore, gained faster than NW steers (3.64 vs 3.26 kg./day; P < 0.0001) for the entire trial (113 day to kill). Aggressive implant steers gained faster than NA steers (3.04 vs. 2.80 kg/day;
P < 0.01), during the first period, tended to gain faster (3.90 vs. 3.70 lbs./day; P < 0.12) during the second period, and gained faster (3.55 vs. 3.35 lbs./day; P < 0.02) for the entire trial.
Early-weaned steers consumed 1,118 lbs. of high-concentrate DM during the first period, and consumed 366 lbs. less DM (2,845 vs. 3,211 lbs.;
P < 0.004) than NW steers during the second period (Table 3). This was due to the fact that EW steers entered the second period at a heavier weight and therefore, reached the final predetermined weight sooner, thus requiring less feed. Overall, EW steers consumed 751 lbs. more high-concentrate DM than NW steers (3,962 vs. 3,211 lbs.; P < 0.0001). Overall, A steers tended (P = 0.19) to consume less DM (3,508 vs. 3,668 lbs.) than NA steers. Early-weaned steers were extremely efficient (0.289 lb./lb.) during the first period, but were less efficient than NW steers (0.191 vs. 0.209 lb./lb., P < 0.003) during the second period due to compensatory growth of the NW steers. However, compensatory growth could not overcome the high efficiency of EW steers in the first period, therefore EW steers were more efficient (0.219 vs. 0.209 lb./lb.) than NW steers when comparing their respective postweaning performance (P < 0.06). Aggressive implant steers tended (P = 0.07) to be more efficient than NA steers (0.297 vs. 0.281 lb./lb.) during the first period, however feed efficiency was not different during the second period (P > 0.17). Overall, A steers were more efficient (0.219 vs. 0.209 lb./lb.) than NA steers (P < 0.06).
| Table 3. Effect of Age at Weaning and Implant Regimen on Feed Intake and Efficiency. | ||||||||
|---|---|---|---|---|---|---|---|---|
| Item | Age at weaning | Implant regimen | P - value | |||||
| EW 113 Days |
NW 205 Days |
Aggressive | Non- Aggressive |
SEM | Wean | Implant | Wean x Implant | |
| No. of animals | 33 | 29 | 34 | 28 | ||||
| Daily dry matter intake, lb./day | ||||||||
| Period 1 (d 113-204) | 12.28 | - | 12.48 | 12.08 | 0.29 | - | 0.28 | - |
| Period 2 (d 204-slaughter) | 19.40 | 18.61 | 19.21 | 18.81 | 0.31 | 0.07 | 0.35 | 0.04 |
| Overall (d 113-slaughter) | 16.5 | 18.61 | 17.66 | 17.53 | 0.22 | 0.01 | 0.65 | 0.05 |
| Total dry matter intake, lb. | ||||||||
| Period 1 (d 113-204) | 1,117.5 | - | 1,136.2 | 1,098.5 | 25.1 | - | 0.28 | - |
| Period 2 (d 204-slaughter) | 2,844.7 | 3,210.3 | 2,936.4 | 3,115.7 | 90.8 | 0.01 | 0.15 | 0.55 |
| Overall (d 113-slaughter) | 3,962.2 | 3,210.3 | 3,507.7 | 3,667.8 | 89.3 | 0.01 | 0.19 | 0.44 |
| Gain/Feed, lb./lb. | ||||||||
| Period 1 (d 113-204) | 0.289 | - | 0.297 | 0.281 | 0.007 | - | 0.07 | - |
| Period 2 (d 204-slaughter) | 0.191 | 0.209 | 0.204 | 0.196 | 0.004 | 0.01 | 0.17 | 0.26 |
| Overall (d 113-slaughter) | 0.219 | 0.209 | 0.219 | 0.209 | 0.004 | 0.06 | 0.06 | 0.53 |
Using an aggressive implant regimen is a viable management option for early-weaned calves. Early-weaned steers consume more high-concentrate DM, and are in the feedlot longer than NW steers, but EW steers are younger at slaughter, convert feed more efficiently, and gain faster from birth until slaughter than do NW steers.
Berg, R. T. and R. M. Butterfield. 1967. Growth patterns of bovine muscle, fat, and bone. J. Anim. Sci. 27:611.
Consortium. 1988. Guide for the care and use of agricultural animals in agricultural research and teaching. Consortium for developing a guide for the care and use of agricultural animals in agricultural research and teaching. Champaign, IL.
Ferrell, C. L., R. H. Kohlmeier, J. D. Crouse, and H. Glimp. 1978. Influence of dietary energy, protein, and biological type of steer upon rate of gain and carcass composition. J. Anim. Sci. 46:255
Fluharty, F. L., T. B. Turner, S. J. Moeller, and G. D. Lowe. 1996. Effects of age at weaning and diet on growth of calves. Ohio Agric. Res. And Dev. Circular 156:29.
Foutz, C. P., H. G. Dolezal, D. R. Gill, C. A. Strasia, T. L. Gardner, E. D. Tinker, and F. K. Ray. 1989. Effects of trenbolone acetate in yearling feedlot steers on carcass grade traits and shear force. Anim. Sci. Res. Rep. Oklahoma State Univ., Stillwater, OK. p. 272.
Goering, H. K. and P. J. Van Soest. 1970. Forage fiber analyses, (apparatus, reagents, procedures, and some applications). Agriculture Handbook #379, USDA, U.S. Government Printing Office, Washington, DC.
Lusby, K. S., R. P. Wettemann, and E. J. Turman. 1981. Effects of early weaning calves from first-calf heifers on calf and heifer performance. J. Anim. Sci. 53:1193.
Myers, S. E., D. B. Faulkner, F. A. Ireland, and D. F. Parrett. 1997. Beef production systems comparing early weaning to normal weaning, with or without creep feeding for beef steers. Beef Res. Rep., Univ. Of Ill., Urbana-Champaign, IL. p. 55.
Neville, W. E. and W. C. McCormick. 1981. Performance of early and normal weaned beef calves and their dams. J. Anim. Sci. 52:715.
Peterson, G. A., T. B. Turner, K. M. Irvin, M. E. Davis, H. W. Newland, and W. R. Harvey. 1987. Cow and calf performance and economic considerations of early weaning of fall-born beef calves. J. Anim. Sci. 64:15.
Richardson, A. T., T. G. Martin, and R. E. Hunsley. 1978. Weaning age of Angus heifer calves as a factor influencing calf and cow performance. J. Anim. Sci. 47:6.
SAS 1988. SAS/STAT® User's Guide: Statistics. SAS Institute, Inc., Cary, NC.
Smith, G. C., J. W. Savell, R. P. Clayton, T. G. Field, D. B. Griffin, D. S. Hale, M. F. Miller, T. H. Montgomery, J. B. Morgan, J. D. Tatum, and J. W. Wise. 1992. Improving the consistency and competitiveness of beef. The final report of the National Beef Quality Audit 1991. National Cattlemen's Association, Englewood, CO.
Trenkle, A. 1990. Evaluation of Synovex-S, Synovex-S + Finaplix-S, and Revalor implant programs in finishing steers. J. Anim. Sci. 68 Suppl: 479.
Van Soest, P. J., J. B. Robertson, and B. A. Lewis. 1991. Methods for dietary fiber, neutral detergent fiber, and nonstarch polysaccharides in relation to animal nutrition. J. Dairy Sci. 74:3583.
Waldman, R. C., W. J. Tyler, and V. H. Brungardt. 1971. Changes in the carcass composition of Holstein steers associated with ration energy levels and growth. J. Anim. Sci. 32:611.
Williams, D. B., R. L. Vetter, W. Burroughs, and D. G. Topel. 1975. Effects of ration protein level and diethylstilbestrol implants on early-weaned beef bulls. J. Anim. Sci. 41:1525.