Implant quality assurance: detection of abscessed implants and Implant quality assurance: detection of abscessed implants and their effect on feedlot performance of beef heifers their effect on feedlot performance of beef heifers

Infrared thermography (IRT) can be used successfully to differentiate abscessed implanted ears from nonimplanted ears 8 days postimplanting. Abscessed ears averaged 5.7 E F warmer than nonimplanted ears when ambient temperature was 60 to 63 E F. Average daily gain and feed efficiency were reduced 8.9% and 8.3%, respectively, over the 91-day feeding period for cattle with abscessed implants compared to cattle with normal implants. Dry matter intake was not affected by an ab-scessed implant and averaged nearly 18.0 lb/head/day for both treatment groups. Ab-scessed implants reduced economic return by $17.70 per head.


Introduction
Growth-promoting implants that combine strong estrogen and an androgen are reported to improve average daily gain by 14.8% and feed efficiency by 7.5% for feeder heifers.They are intended to be placed aseptically as a series of pellets in the subcutaneous tissue of the middle one-third of the back of the ear.Feedlot implant audits by Fort Dodge Animal Health for 1996 and 1997 found 6.0% (range by state = 2.2 to 33.3%) of 109,388 implants to be classified as problem implants: abscessed following placement; missing at audit; or improperly placed in the ear, such as bunching or crushing of pellets or pellets placed in the cartilage.Abscess formation and its sequelae accounted for over 60% of the observed problem implants.The effect of abscessed implants on performance has not been well documented.This trial evaluated the thermographic appearance of ears following the placement of aseptic or septic implants in the ears of feedlot heifers and the performance of those cattle during a 91-day growing period.

Experimental Procedures
A total of 72 British crossbred heifers (400 to 550 lb) were assigned to one of two treatment groups in May,1997.Group A (normal implant) received a Synovex®-H (200 mg testosterone + 20 mg estradiol benzoate, Fort Dodge Animal Health, Overland Park, KS) implant in an ear washed with a brush saturated with Nolvasan® solution (Fort Dodge Animal Health) at 6 oz. per gallon of water.Group B (abscessed implant) received a Synovex-H implant in an ear to which a slurry of water and cattle feces had been applied immediately prior to and after implanting.The nonimplanted ear served as the control for thermographic evaluation.The heifers were stratified by weight and fed in pens of six head each with a total of six replicates per treatment.The heifers were fed once per day a sorghum silage plus dry rolled corn ration (Table 1) for a 91-day growing period.Feed consumption, weight gain, and gain efficiency were recorded for each pen.Thermal imaging was done on unrestrained cattle in their pens 8 days after implantation.The front of each ear was imaged from a distance of 6 to 24 feet.A high resolution, short wave (3 to 5 um), infrared thermal imaging camera (Radiance PM®, Amber Engineering, Goleta, CA) was used.An analysis of a rectangular area on the front of each ear was made to determine minimum, maximum, and mean temperatures.Analysis of variance was used to determine the relationship between mean ear temperature (response variable) and treatment.Least square mean temperatures of ears having normal and abscessed implants were compared to those of nonimplanted control ears using Tukey's correction for multiple comparisons.Analysis of variance was used to evaluate average daily gain (ADG), feed intake, and gain efficiency over the 91-day feeding period.
For the 91-day growing period, cattle with abscessed growth implants showed $17.70 lower return per head compared to their counterparts with nonabscessed implants.That number is based on a 650 lb heifer price of $74/cwt and a ration cost of $120 per ton.
Infrared thermography (IRT) can be used as part of an implant quality assurance program when cattle are screened in the pen within 8 days of implanting.The use of IRT as a screening tool would eliminate multiple handling of cattle, would provide a rapid assessment of implanting technique as compared to conventional quality assessment programs, and would decrease reliance on quality audits at slaughter.

Table 2 . Effects of Abscessed Growth Promotant Implants on Feedlot Performance of Beef Heifers a
a Average initial weight of both treatment groups was 446 lb.