2007 Annual Report

Beef Section

Dickinson Research Extension Center
1041 State Avenue
Dickinson, ND 58601

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Drought Management: Effect of Early Weaning on Immune Response,
Backgrounding and Finishing Performance, and Economics

J. Harper1 and D.G. Landblom2

1Dickinson State University, Department of Agriculture and Technical Studies
2
North Dakota State University, Dickinson Research Extension Center

This paper summarizes an undergraduate research proect that was conducted at the Dickinson Research Extension Center under the direction of Animal Scientist, Doug Landblomprepared cooperatively with Jeremy Harper, Dickinson State University, Department of Agricultural and Technical Studies student to fulfill Jeremy’s undergraduate research proect requirement for graduation with a degree in Agricultural Studies from Dickinson State University.

Abstract: Forty-eight crossbred cows and calves were used to evaluate the effect of weaning date (Aug.-EW vs. Nov.-NW) immune response, pasture, backgrounding and finishing performance, carcass closeout, and economics as a drought management procedure. Antibody titer measured preweaning, weaning, and at 28-30 day intervals through 60 days of finishing increased numerically from preweaning vaccination to 30d postweaning for BVD Types I and II, but the difference was not significant. IBR declined from initial vaccination over time and was greater for EW steers (P< 0.01). At weaning, EW steers were transferred to the University of Nebraska feedlot at Scottsbluff, NE and NW continued to graze for 92d until weaning in November, and then transferred to the feedlot in Nebraska. For growth, pasture vs. drylot gain and ADG did not differ (P=0.38); 56d backgrounding: EW grew faster (P<0.01) and were more efficient (P<0.01); 84d backgrounding: ADG did not differ (P>0.01), but feed efficiency was improved for EW (P<0.05. For overall backgrounding and finishing performance, age at slaughter did not differ (P>0.01), but EW required 95 more days on feed. Finishing ADG was greater for NW (P<0.01), but feed efficiency did not differ (P>0.01). Carcass closeout values for hot carcass weight, dressing percent, fat depth, ribeye area, yield grade, and percent Choice quality grade did not differ (P>0.01). Carcass price was slightly higher for EW steers, but price did not differ significantly (P=0.95). Carcass net return was $54.40 per head greater for NW steers. While early weaning did not provide the highest return, these data clearly show that EW is a viable drought management strategy.

Key Words: Early Weaning, Immune Response, Postweaning Performance, Drought Management

Introduction: This drought management investigation is multi-faceted; encompassing range sparing, effect of weaning date on immune response, backgrounding and finishing, performance, closeout value, and partial system economics. This Capstone Project report focuses on postweaning calf performance only. Impact on pastures and cow performance can be found in a separate report.

An animal’s immune response is one of natures many phenomena. Calves start to build their immune system immediately upon the time of birth. The ability for a calf to build immunity towards disease is essential, both from the animal’s health standpoint and from the economic standpoint of the producer. A producer must keep his/her herd healthy especially since their profit margins are usually slim as a result of what it costs in order to produce the product. As we try to cut costs, we cannot overlook an animal’s health. All prevention steps should be taken when trying to keep the animals healthy. After all, a dead calf gives no return to the producer. A producer’s profit margin is what keeps him/her in business. Sick calves create costs not only from the drugs that it takes treat the sickness, but they have other costs that relate to decreased daily gain and overall poor performance.

Performance of early-weaned calves during the backgrounding and finishing phase is important and research has shown calves weaned a 100 to 150 days of age were heavier and younger at slaughter than that of normal weaned calves that are around 230 days old when weaned (Peterson et al., 1987). Meyers et al (1999) found that 40% of the calves that were subjected to early weaning graded average choice or ever higher than calves that were weaned at the normal weaning age.

Materials and Methods: Over a year’s time, 48 steers from the NDSU - Dickinson Research Extension Center were used in this study. Spring-born steer calves were weaned from cows at either 140 days (EW) or 215 days of age (NW). Cow body weight and condition scores were recorded in order to determine the impacts of weaning on cow performance. The mother cows received Pfizer’s preventative shots Scour-Guard-3 during their third trimester of pregnancy, and Preg-Guard Gold-10 as their pre-breeding vaccination. Three weeks before the calves were weaned, the calves received a preconditioning vaccination with Pfizer’s Ultrabac-7, Bovi-shield Gold-5, and One-Shot. The booster shots were given at the time of weaning. Early and normal weaned calves were weighed at August weaning (EW) and NW steers continued to nurse their mothers until weaning in November. Blood samples were drawn for serum recovery 3 weeks before weaning, at weaning, and at 28-30 day intervals until the steers were on finishing rations for about 60 days. Immediately after pasture weaning, the EW calves were transported to the University of Nebraska’s Panhandle Feedlot located in Scottsbluff, Nebraska. The steer calves were implanted with on arrival with the estrogenic implant Ralgro®.

Serum samples recovered from blood draws were analyzed to determine antibody titer levels for infectious Bovine Respiratory disease (IBR) and Bovine Virus Diarrhea types I and II (Table 1) at the Texas A&M Veterinary Diagnostic laboratory, Amarillo, Texas.

The steers stayed on feed at the UNL Panhandle Feedlot from weaning to final harvest and growth performance was monitored at 28 day intervals. Live animal ultrasound was used to determine final harvest endpoint which was based on back fat depth (BF), ribeye area (REA), and percent intramuscular fat (IMF). The harvest target for BF was set at 0.50 inch, ribeye was set at 12.0 sq. inch, and percent intramuscular fat was set at 4.0% (low Choice).

Results: Pasture (NW) versus feedlot (EW) performance is shown in Table 2 and 84 day backgrounding performance is shown in Table 3. Overall, backgrounding and finishing performance is summarized in Table 4 and carcass closeout results, and weaning system economics are shown in Table 5.

Immune Response:

Pasture versus Feedlot Growth:
84-Day Backgrounding Performance:
Overall Backgrounding and Finishing Performance:
Carcass Closeout:
Postweaning Economics:
Conclusion: Although early weaned steers in this investigation did not return as much as their normal weaned counterparts, using early weaning and retained ownership is an effective drought management strategy. The data presented here only accounts for postweaning calf performance. However, when cow body condition improvement of from 0.80 to 1.0 and improved rebreeding performance are taken into account, an early weaning system becomes a very effective drought management procedure. New early weaning research is evaluating the use of annual forage grazing as an alternative to drylot for early weaned calves.

Literature Cited: Meyers, S.E., D.B. Faulkner, F.A. Ireland, L.L. Berger, and D.F. Parrett. 1999. Production systems comparing early weaning to normal weaning with or without creep feeding for beef steers. J. Anim. Sci. 77:300-310.

Peterson, G.A., T.B. Thuner, K.M. Irvin, M.E. Davis,

H.W. Newland, and W.R. Harvey. 1987. Cow and calf performance and economic consideration of early weaning of fall-born beef calves. J. Anim. Sci. 64:15-22.

 

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