Estimating the Effects of Animal Health on the Performance of Feedlot Cattle

Transcription

1 PEER REVIEWED Estimating the Effects of Animal Health on the Performance of Feelot Cattle Max Irsik, DVM, MAB 1 ; Michael Langemeier, PhD 2 ; Te Schroeer, PhD 2 ; Mark Spire, DVM, MS, DACT 3 ; Joseph Deen Roer, DVM, PhD, DABVT 4 1 College of Veterinary Meicine, University of Floria, Gainsville, FL Department of Agricultural Economics, Kansas State University, Manhattan, KS College of Veterinary Meicine, Kansas State University, Manhattan, KS Schering-Plough Animal Health, Canyon, TX Abstract It is generally accepte that performance of feelot cattle is negatively impacte as health problems increase. The magnitue of impact that health problems have on overall or specific performance parameters is not well efine for feelot cattle. This stuy etermine the effect of animal health on the performance of feelot cattle. Multiple regression moels were evelope to ai in the performance analysis for fee conversion, average aily gain, ae cost an cost of gain. Results of this stuy showe that for each percentage increase in mortality in a pen of cattle the fee conversion ratio increase by 0.27 pouns (lb) (0.12 kg), the average aily gain ecrease 0.08 lb (0.036 kg) per ay an ae costs increase $1.00 per hea. For each percentage increase in treatments for a pen of cattle, eath loss increase by 0.143%. A 10% treatment rate woul equate to a 1.7% eath loss. These ata shoul be useful to estimate performance of fe cattle. The stuy confirms an quantifies the negative effect of averse health on fe-cattle performance. Résumé On croit généralement que la performance es bovins en parc engraissement iminue avec l augmentation es problèmes e santé. Chez les bovins en parc engraissement, l amplitue es retombées e ces problèmes e santé au niveau es inices e performance généraux ou ciblés n est pas bien établie. Cette étue avait pour but e éterminer l effet e la santé animale sur la performance chez les bovins en parc engraissement. Des moèles e régression multiple ont été utilisés ans l analyse e la performance pour la conversion alimentaire, le gain moyen quotiien, le coût accru et le coût u gain. Les résultats iniquent que pour chaque augmentation un pourcent u taux e mortalité ans un enclos e bovins, il y avait une augmentation e 0.27 lb (0.12 kg) ans la conversion alimentaire, une iminution e 0.08 lb (0.036 kg) ans le gain moyen quotiien et une augmentation e $1.00 par tête es coûts accrus. Les pertes imputables à la mort augmentaient e 0.143% pour chaque augmentation un pourcent es traitements ans un enclos e bovins. Un taux e traitement e 10% serait l équivalent une perte imputable à la mort e 1.7%. Ces onnées evraient être utiles pour estimer la performance es bovins en engraissement. Cette étue a permis e confirmer et e quantifier les retombées négatives une mauvaise santé au niveau e la performance es bovins en engraissement. Introuction The cattle feeing inustry in the Unite States is a capital intensive, high-risk business that relies heavily on economies of scale to minimize costs an maximize returns. Profit margins for fe cattle are often small an variable, while losses can be large. One tool cattle feeers utilize to manage economic risk is estimating the performance of fe cattle, then applying that information to cattle currently on fee or to future purchases of cattle. Numerous variables affect performance of feelot cattle. Some variables are more easily manage than others, such as purchase weight, origin of cattle, type or genetic makeup of cattle, an backgroun. Health liabilities cattle may experience are more ifficult to manage. Several stuies have provie benchmarks for health measurements within feelots. 3,10,12,15,16 Average eath loss for fe cattle has been reporte to range from 1 to 1.3%, 3,10,12,16 with an average morbiity rate of 8%, SUMMER,

2 which represente 16 years of recors an over 7 million hea of cattle. 3 The most frequent cause of illness in feelot cattle is bovine respiratory isease (BRD). 3,12,15 Estimate cost to treat fe cattle has also been reporte. In a 1999 US Department of Agriculture survey, The Health Management an Biosecurity of U.S. Feelots: Part III, the cost to treat sick cattle within a feelot range from $16.49 per hea to treat acute interstitial pneumonia to $6.14 for igestive isease. 15 In another stuy, a 10% morbiity rate was associate with a meicine cost of $2 for each animal markete. 3 A review of the literature reveals that there are important health concerns for feelot cattle, with the most commonly reporte isease being Bovine Respiratory Disease (BRD). There is a significant relationship between animals with lung lesions at slaughter, those treate for respiratory isease an ecrease average aily gains. Aitionally, it has been emonstrate that performance of feelot cattle (average aily gain, fee conversion) has a significant effect on profitability. Stuies have evaluate the relationship between cattle with lung lesions at slaughter an/or treatment for respiratory isease an the associate effect on average aily gain (ADG). 2,4,5,6,7,17 Cattle with lung lesions associate with cranial-ventral bronchopneumonia ha a poun (lb) (0.03 kg) reuction in ADG. 2 Wittum et al evaluate treatment of cattle for respiratory isease an the associate weight gain an foun no significant association between treatment of cattle for respiratory isease an weight gain. There was, however, a significant association between lung lesions foun at slaughter an weight gain. Cattle with pulmonary lesions ha lb (0.075 kg) less ADG. 17 Garner et al reporte a significant relationship between treating cattle an reuce gains. Cattle treate for respiratory isease average 19.8 lb (9 kg) less total gain than untreate cattle. 6 It has been note that the total number of cattle with lung lesions at slaughter is much greater than the number of animals treate for respiratory isease while on fee. 2,6,17 Garener el al reporte that 37% of 102 hea of untreate cattle ha lung lesions at slaughter, while 48% of the treate cattle exhibite lung lesions. Wittum foun lesions in 68% of untreate animals, an Bryant reporte 47% of a group of calves ha lung lesion at slaughter, with 17% of those calves iagnose with respiratory isease. 2,6,17 These finings suggest there may be a significant number of animals with inapparent or subclinical respiratory isease, an treating clinically affecte cattle may be inaequate to prevent significant prouction losses attributable to respiratory isease. 2,6,17 Economic impact of respiratory isease in steers uring the finishing perio is significant. Garener compare cattle with lung lesions an associate active or inactive lymph noes to cattle with no lung lesions. Cattle without lung lesions ha a $20.03 higher net return compare to cattle with lung lesions an inactive lymph noes. Steers with lung lesions an active lymph noes ha $73.78 lower net return than cattle with no lesions. 4,5 Results from the Texas A&M Ranch to Rail Program inicate healthy steers ha an average profit of $176, while sick steers average $23 profit. 14 Factors contributing to cattle feeing performance an profitability have been reporte. 1,8,9,11,14 Fe cattle sales price, feeer cattle purchase price, corn prices, fee conversion (FC), ADG an interest rates all significantly contribute to profit of fe cattle. Price risk accounte for 85-95% of profit variability, an animal performance accounte for 5 to 10% of profit risk. Variables that significantly impact the cost of gain for fe cattle are corn price, FC an ADG. These variables explaine 92 to 94% of the variability in cost of gain (COG). 1 Another stuy conclue that in aition to input prices, output prices an animal performance, gener, placement weight, facility esign, an to a lesser extent placement season, significantly impact cattle feeing profitability. 9 There is limite ata on the impact of isease on the performance of pens of fe cattle. While animal performance is not the major eterminant of cattle feeing profitability, it oes have an effect. This stuy focuses on effects of animal health on performance of feelot cattle. More specifically, it attempts to quantify the effects of animal health on three measures of performance: FC, ADG an COG. These performance measures are use as benchmarks when comparing sets of cattle. They are often use when evaluating feelots on their ability to fee cattle for maximum performance, least cost an highest net return. Materials an Methos Feelot ata were collecte from customer closeout sheets from two western Kansas commercial feelots. Data obtaine from the close-out sheets inclue hea count, gener, percent mortality, number of cattle treate, ate in, ate out, average hea ays, average in-weight, average out-weight, gain per hea, FC (ry matter [DM] basis), ADG, COG, average fee consumption per hea (DM basis), ration cost, ae cost, origin an backgroun. Data were collecte for steers, heifers an mixe pens of cattle place on fee from August 2000 through January The total number of pens was 673 (53,890 hea): 332 pens of steers (26,061 hea); 220 pens of heifers (18,828 hea); an 121 mixe pens containing both steers an heifers (9,001 hea). Linear regression moels were evelope to analyze the ata an evelop statistics for FC, ADG, ae cost (AC) an percent mortality (MORT). 66 THE BOVINE PRACTITIONER VOL. 40, NO. 2

3 EViews, evelope by Quantitative Micro Software, was utilize to provie estimate coefficients an associate statistics for the multiple regression moels. Multivariate regression moels were use,, represente by the following equation: Y i = β 0 + β 1 X i + β 2 X i +.+ β n X i + e i where: Y i is the epenent variable to be estimate, β 0 β n are the estimate regression coefficients, an X i are the inepenent variables, with i representing a pen of cattle an e i as the error term. 13 Depenent variables were FC, ADG, AC an percent mortality (MORT). Pen-level ata for the inepenent variables was obtaine from close-out sheets from pens of fe cattle. Inepenent variables for the FC, ADG an AC moels were ientical. These variables were MORT, average in-weight per hea (AVIWT), average out-weight per hea (AVOWT) an ummy variables. Dummy variables were gener of cattle within a pen steers (ST), heifers (HFR) or mixe (MX); quarter of the year the pen of cattle were shippe, (Q1, Q2, Q3 an Q4); origin of the cattle, Kansas (KS), Oklahoma (OK), Texas (TX), Southeast (SE), or Northeast (NE); backgroun of the cattle (sale barn, preconitione, grass, or wheat); an the feelot where the cattle were fe, yar 1 or yar 2. Default variables for the ummy groups were ST for the gener, Q1 for the quarter of the year the pen was shippe, KS for the origin, sale barn for the backgroun variable, an yar 1 for the fee yar where cattle were fe. The inepenent variable for the percent mortality moel (MORT) was percent treatments (TRT). Moels were evaluate by consiering the sign on each estimate coefficient, evaluating the statistical significance for each estimate coefficient utilizing a t-statistic an probability value obtaine from a two-taile t test, looking at the coefficient of etermination or (R 2 ) for each moel, a measure of how well the inepenent variables explain the epenent variable, an utilizing an F-test to evaluate the significance of the groups of inepenent variables. Fee conversion is efine as the amount of fee consume per poun of gain, an is reporte on an asfe basis, or on a ry basis. In this stuy, FC on a ry basis was analyze. Fee conversion was calculate by iviing the total amount of fee fe to a group of cattle by the total pouns gaine by that group of cattle. It is reporte in close-out sheets with eas-in or eas-out. In this stuy, FC with eas-in was evaluate. Average aily gain is a measure of the average gain per ay for cattle in a pen. Average aily gain was calculate by iviing average fee consumption per ay by the fee conversion ratio. Average aily gain was evaluate on a eas-in basis. Ae costs inclue the cost of meicine to treat sick cattle, processing, metaphylaxis, yarage, association ues an insurance. Yarage, association ues an insurance are stanar costs associate with each pen of cattle. Cost of meicine, processing an metaphylaxis will vary between pens. Close-out sheets sum ae costs an fee costs to obtain the total cost for a pen. Cost of gain is reporte as the total cost (fee cost plus ae cost) to prouce one hunre pouns of live gain. It is reporte as ollars per hunre weight of gain. Cost of gain is calculate by iviing the total cost for a pen of cattle while on fee by the total pouns of gain for that pen. Cost of gain is reporte in close-out ata with the eath loss inclue (eas-in) or exclue (eas-out). In this stuy, the cost of gain is evaluate with eath loss inclue (eas-in). Percent mortality or eath loss for a pen was calculate by iviing the number of cattle that ie within a pen by the total number of cattle receive for that pen. Percent treate was etermine by iviing the number of cattle pulle an treate within a pen by the total number of cattle receive for that pen. Each animal pulle an treate with one roun of therapy an returne to the home pen before another regimen was aministere was consiere to have unergone one treatment. A roun of therapy was efine as a treatment regime outline by the veterinarian in charge, an usually involve an animal being treate or maintaine in the hospital for three to four ays, receiving a single roun of treatment with a specific antibiotic before being sent back to its home pen. If an animal was returne to the home pen an subsequently re-pulle an retreate, that was consiere a secon treatment. If an animal was pulle an treate with two rouns of therapy before going back to the home pen, that was consiere as one pull an one roun of treatment. Cattle pulle as bullers were not consiere in the ata set. To analyze the relationship between eath loss an the iniviual measures of performance, FC, AC, or ADG, the iniviual moels for FC, AC an ADG were utilize. To analyze the relationship between percentage of cattle treate an performance, two steps were involve. First the relationship between mortality an the percent of cattle treate within a pen was estimate utilizing the MORT moel. Then values for percent mortality utilizing the MORT moel were calculate for iffering percentages of cattle treate within a pen. The secon step was substituting the values calculate from the MORT moel as the values for the percent mortality variable in the FC, AC an ADG moels. Values obtaine from these moels were reporte as the relationship between percent treatments, an FC, ADG an AC. Evaluating the effects of animal health, (percent mortality, percent treatments) on cost of gain involve the AC, FC an MORT moels an an Excel sprea- SUMMER,

4 sheet. The moels provie inputs for fee conversion, ae cost or eath loss to a spreasheet esigne to represent a fe cattle close-out performance recor. The spreasheet performe the calculations to etermine the associate COG. When evaluating mortality, COG was recalculate when inputs from the FC an AC moel change as percent mortality, an inepenent variable, was change in these moels. To evaluate the relationship between percent treatments an COG, the MORT moel was utilize along with the FC an AC moels. The MORT moel estimate the effects of treatments on mortality. The value for percent mortality from the MORT moel provie a means to evaluate the effect of percent treatments on fe cattle performance. The percent mortality from the MORT moel was substitute as the value for the percent mortality variable in the FC an AC moels. The values obtaine from the FC an AC moels were then utilize as inputs into the COG spreasheet. The values obtaine from the COG spreasheet reflecte the COG associate with varying levels of treatment. COG for a pen of fe cattle is reporte as the total cost to prouce 100 lb of live gain. Total cost for a pen of fe cattle is etermine by aing two components, total ae cost an total fee cost. The cost per ton of ry fee in this stuy was hel constant at the mean cost per ton of ry fee ($143.83) obtaine from the ata set when etermining total fee cost. Results The summary statistics for the pens of cattle use in this stuy may be foun in Table 1 an Table 2. The average in-weight was 782 lb (355.4 kg) for steers, 701 lb (318.6 kg) for heifers an 785 lb (356.8 kg) for mixe pens. The average out-weight was 1299 lb (590.4 kg) for steers, 1183 lb (537.7 kg) for heifers an 1272 lb (578.2 kg) for mixe pens. Multicollinearity was a problem in this stuy. There was a positive correlation (.678) between percent treatments an percent mortality. As the percent of treatments increases or ecreases, the percent of cattle ying also increases or ecreases. The more highly correlate two (or more) inepenent variables are, the more ifficult it becomes to accurately estimate the coefficients of the true moel. 13 To eal with the problem of multicollinearity, either percent mortality or percent treate was use as one of the inepenent variables, with no moels utilizing both as inepenent variables. Fee Conversion Moel The FC moel ha an R-square of 0.56; the inepenent variables thus explaine 56% of the variation in the epenent variable. Table 3 provies the estimate coefficients, their associate t-statistics an probability values for the FC moel. A variable with a probability 0.05 was consiere significant. Signs for the estimate coefficients were as preicte, except for the sign on the coefficient for the heifer variable. Heifers were hypothesize to have a higher fee conversion ratio when compare to steers. The moel estimate the heifer FC ratio to be lb (-0.05 kg) lower than the FC ratio for steers, but the ifference was not statistically significant. Estimate coefficient for percent mortality was significant with a value of For every percentage increase in mortality, keeping all other variables constant, the FC ratio increase by 0.27 lb (0.12 kg) of ry fee for each poun of gain. Estimate coefficients for the average in-weight an the average out-weight were also significant. The FC ratio increase by lb ( kg) for each poun of increase in the average in-weight, an ecrease by lb ( kg) for each poun of increase in the average out-weight. There was no significant ifference in FC between the ifferent geners. Cattle from the southeast ha significantly smaller FC ratios, while cattle from the northeast ha significantly higher FC ratios when compare to cattle originating from Kansas. The FC ratio for cattle shippe in the secon quarter was significant an estimate to be lower by lb (-0.16 kg) compare to cattle shippe uring the first quarter. The signs on the coefficients for the backgroun of cattle were as hypothesize: preconitione cattle an cattle off wheat woul have ecrease FC ratios, while cattle off grass woul have increase FC ratios. None of the estimate coefficients ealing with cattle backgroun were significant, however. Cattle fe in yar 2 ha significantly lower FC ratios compare to cattle fe in yar 1. An F-test was performe on each group of ummy variables. The quarter of the year the cattle were shippe an the origin of cattle were foun to be significant. Average Daily Gain Moel The moel for ADG ha an R-square of 0.75, inicating that 75% of the variability in ADG was explaine by the inepenent variables. Table 4 provies the estimate coefficients, their corresponing t-statistics an probability values. The percent mortality variable was statistically significant with an estimate negative coefficient of , meaning ADG woul ecrease by 0.08 lb (0.036 kg) for each 1.0% increase in eath loss. AVIWT an AVOWT were both significant. The estimate coefficient for AVIWT was a negative , inicating as the average weight of an animal place on fee increase by one poun, ADG woul ecrease lb ( kg). The coefficient for AVOWT was inicating, as the average close-out weight increase by 68 THE BOVINE PRACTITIONER VOL. 40, NO. 2

5 Table 1. Summary statistics for feelot performance ata. Variable Mean Meian Min Max Stanar eviation Hea count per pen Mortality (%) a 2.30% 1.16% 0.00% 26.51% 3.83% Treate (%) b 13.62% 6.06% 0.00% % 17.76% Hea ays In-weight (lb) c Out-weight (lb) Gain per hea (lb) e FC (lb fee /lb of gain) f Fee consumption g ADG (lb / ay) Cost of gain ($ / cwt) $53.20 $50.34 $31.38 $ $15.66 Ration cost ($ / ton) h $ $ $ $ $3.73 Ae cost ($ / h) i $22.57 $19.29 $3.40 $61.63 $8.81 a Mortality expresse as a percentage of cattle receive. b Percent treate expresse as a percentage of cattle treate per number of cattle receive. c In-weight is the average weight per hea of cattle receive. Out-weight is the average weight per hea for cattle shippe. Gain per hea is the ifference between the in-weight an the out-weight. f Fee conversion is expresse on a ry basis. g Fee consumption is the average aily consumption an expresse on a ry basis. h Ration cost is ollars per ton of ry ration. i Ae cost is the cost per hea other than fee. Inclues yarage, meicine, fee processing, insurance, Kansas Livestock Association ues. Table 2. Summary statistics for moel ummy variables. Variable Mean Meian Min Max Stanar eviation Steers a Heifers Mixe Q1 b Q Q Q Kansas c Oklahoma Texas Southeast Northeast Sale barn Preconitione Grass Wheat FY1 e FY The efault ummy for each set of ummy variables was: a steers for gener of the pen, b quarter 1 for the quarters of year cattle were shippe, c Kansas for the origin of cattle, sale barn for the backgroun, e feelot 1 for where cattle were fe. SUMMER,

6 Table 3. Results for fee conversion moel (lb ry fee / lb of gain). Variable Estimate coefficient St. Error t-statistic Prob. Intercept Percent mortality Ave. in-weight Ave. out-weight Mixe Heifers Q Q Q Oklahoma Texas Southeast Northeast Preconitione Grass Wheat Feelot R-square 0.56 Mean epenent var 6.67 Ajuste R-square 0.55 S.D. epenent var 1.60 S.E. of regression 1.07 F-statistic Sum square resi Prob (F-statistic) 0.00 Log likelihoo observations Table 4. Results for average aily gain moel (lb per ay). Variable Estimate coefficient St. Error t-statistic Prob. Intercept Percent mortality Ave. in-weight Ave. out-weight Mixe Heifers Q Q Q Oklahoma Texas Southeast Northeast Preconitione Grass Wheat Feelot R-square 0.75 Mean epenent var 3.24 Ajuste R-square 0.75 S.D. epenent var 0.61 S.E. of regression 0.31 F-statistic Sum square resi Prob (F-statistic) 0.00 Log likelihoo observations 70 THE BOVINE PRACTITIONER VOL. 40, NO. 2

7 a poun, ADG for cattle in that pen was increase by lb ( kg). The ADG for pens containing mixe geners or heifers was not significant when compare to the ADG for pens of steers. ADG for cattle shippe uring the secon, thir an fourth quarters of the year was greater an significantly ifferent compare to cattle shippe in the first quarter. Cattle from Oklahoma an Texas ha significantly lower ADG than Kansas cattle, while cattle out of the southeast ha significantly higher ADG. Cattle preconitione or off grass also ha significantly higher ADG than sale barn cattle. When looking at the ifferent groups of variables, the gener of the cattle, the quarter shippe, the origin of the pen of cattle an the backgroun of the cattle were all significant. Ae Cost Moel The AC moel ha an R-square of 0.679, meaning 68% of the variability in ae cost was explaine by the inepenent variables. Table 5 provies the estimate coefficients, their corresponing t-statistics an probability values. Percent mortality was significant when estimating AC. For each percentage increase in eath loss for a pen of cattle, AC woul increase $1.00 per hea. Average in- an out-weights were also significant when estimating AC. The estimate coefficient for AVIWT was a negative $0.028, meaning as cattle come into the yar heavier their AC ecreases. The coefficient for AVOWT was $0.006, which means the AC increases by $0.006 per lb of animal shippe. The AC associate with shipment ates was significant. Cattle shippe in the secon, thir an fourth quarters of the year ha $2.66 per hea lower AC on average compare to cattle shippe in the first quarter of the year. Cattle from Oklahoma an the Northeast ha significantly higher AC compare to Kansas cattle. Cattle that were preconitione, or off wheat or grass, all ha significantly lower AC, averaging $2.70 per hea compare to sale barn cattle. When looking at significance of the groups of variables, gener of cattle, quarter of the year when cattle were shippe, origin an cattle backgroun were all significant. Mortality Moel The R square for the MORT moel was 0.45, meaning 45% of the variability in percent mortality was explaine by the inepenent variable, percent treate. The estimate coefficient for percent treate was significant, with a value of 0.14%. Using the estimate coefficient for percent of cattle treate, for each percent- Table 5. Results for ae-cost moel (ollars per hea). Variable Estimate coefficient St. Error t-statistic Prob. Intercept Percent mortality Ave. in-weight Ave. out-weight Mixe Heifers Q Q Q Oklahoma Texas Southeast Northeast Preconitione Grass Wheat Feelot R-square 0.68 Mean epenent var Ajuste R-square 0.67 S.D. epenent var 8.81 S.E. of regression 5.05 F-statistic Sum square resi Prob (F-statistic) 0.00 Log likelihoo observations SUMMER,

8 age increase in treatments, eath loss woul increase by 0.14%. Using the moel, a 10% treatment rate woul preict a 1.7% eath loss for a pen of cattle. Cost of Gain Spreasheet Table 6 examines the impact of increase mortality on FC, ADG, AC an COG. When values for mortality, varying from 0 to 10%, were utilize in the AC an FC moels, keeping other inepenent variables at their means with ummy variables set to their efaults, FC went from 6.25 lb to 8.92 lb ( kg), ADG range from 3.36 lb to 2.36 lb ( kg) an AC range from $22.56 to $32.57 per hea. Substituting values for FC an AC into the cost of gain spreasheet, COG range from $49.49 to $72.85 per cwt. Table 7 examines the impact of increases in the percent of animals treate on FC, ADG, AC an COG. Values obtaine from the mortality moel were plugge into the FC, ADG, or AC moels to evaluate effect of treatments on performance parameters. When values for percent treatment range from 0 to 100%, FC went from 6.34 lb (2.88 kg) when no cattle were treate to lb (4.65 kg) when all cattle were treate; ADG went from 3.32 lb when no cattle were treate to 2.06 lb (0.93 kg) when all cattle were treate; an AC range from a low of $22.86 per hea when no animals were treate to $37.51 when all cattle were treate. COG increase from $50.13 per cwt. when no animals were treate to a high of $85.66 per cwt. when all cattle were treate. Impact of iniviual variables on FC, ADG, AC an COG are provie in Table 8. A base value was establishe utilizing mean values for percent mortality, AVIWT, AVOWT, with ummy variables set to their efaults which were steers, shippe in the first quarter, from Kansas, out of a sale barn, an fe in feelot 1. The impact of each inepenent variable was then increase by 1 stanar eviation, with all other variables set to their means or efault values. To evaluate the impact of each ummy variable, the inepenent variables were reset to their mean values, an each ummy was iniviually change, while the other sets of ummies were set to their efault values of zero. Discussion Animal health was foun to have a significant effect on performance of feelot cattle. As incience of isease (measure by animal health treatments) increase, performance an profitability of cattle ecrease. For the pens of cattle in this stuy, percent mortality or percent of treatments ha the most impact Table 6. Relationship of percent mortality to fee conversion, average aily gain, ae cost an cost of gain. Percent mortality Fee conversion (lb) a Average aily gain (lb) b Ae cost c Cost of gain $22.56 $ $23.06 $ $23.56 $ $24.06 $ $24.56 $ $25.06 $ $25.56 $ $26.06 $ $26.56 $ $27.06 $ $27.06 $ $28.06 $ $28.56 $ $29.06 $ $29.56 $ $30.06 $ $30.56 $ $31.06 $ $31.56 $ $32.07 $ $32.57 $72.85 a Fee conversion is ry lb of fee per lb of gain b Average aily gain is lb per hea per ay c Ae costs is in ollars per hea Cost of gain is measure in ollars per cwt. 72 THE BOVINE PRACTITIONER VOL. 40, NO. 2

9 Table 7. Relationship of percent of cattle treate on fee conversion, average aily gain, ae cost an cost of gain. Percent treate a Fee conversion (lb) b Average aily gain (lb) c Ae cost Cost of gain e a Percent of treatments for pen b Fee conversion ry lbs fee per lb of gain c Average aily gain in lb per hea per ay Ae cost in ollars per hea e Cost of gain in ollars per cwt. on animal performance. Either of these animal health parameters (mortality or treatments) impacte FC, ADG an the AC component of COG. Analysis of this ata provie some helpful thumb rules for correlating animal health to pen-level performance. 1. Fee Conversion: fee conversion ratio increase by 0.27 lb (0.12 kg) for each percentage increase in eath loss. 2. Average Daily Gain: average aily gain ecrease by 0.08 lb (0.04 kg) for each percentage increase in eath loss. 3. Ae Costs: ae costs increase by $1.00 per hea for each percentage increase in eath loss. 4. Mortality: eath loss for a pen of cattle can be estimate by multiplying the percent treate by The mortality moel escribe in this stuy provies insight to the range of impact of treatments on FC, ADG an the AC portion of cost of gain. The ata an moels from this stuy suggest that if no animals are treate, the FC ratio woul be 6.34, ADG woul be 3.32 lb (1.15 kg) an AC woul be $ Conversely, using the same moel with all cattle receiving treatment, the FC ratio woul be 10.24, ADG woul be 2.06 lb ( 0.94 kg) an AC woul be $ This woul result in COG values ranging from $50.13 per cwt. if no animals were treate to $85.66 per cwt. if all cattle were treate. Conclusions Data presente in this stuy are from two feeyars locate in Kansas. Values estimate for the inepenent variables in this stuy are helpful when evaluating fe cattle performance. Values obtaine from this stuy irectly apply to two commercial feeyars locate in Kansas, an may not apply to feeyars in other geographic regions. It woul be interesting to examine ata from other feeyars an regions to etermine if similar trens were observe. The $35.00 per cwt sprea in cost of gain between a pen of cattle with no animals treate an a pen of cattle with all animals treate is economically relevant an important to the cattle feeing inustry. References 1. Albright ML, Schroeer TC, Langemeier MR: Determinants of cattle feeing cost of gain variability. Prouction Ag 7: , SUMMER,

10 Table 8. Impact of iniviual inepenent variables on fee conversion, average aily gain, ae cost an cost of gain. Variable Fee conversion (lb) Average aily gain (lb) k Ae costs Cost of gain Base a $24.86 $54.68 Treate b $27.48 $60.64 Mortality c $28.69 $63.54 Ave. in-weight $21.63 $62.20 Ave. out-weight e $25.51 $49.08 Mixe f $25.52 $54.88 Heifers $23.90 $53.66 Quarter 2 g $22.67 $51.63 Quarter $22.02 $53.46 Quarter $21.89 $53.66 Oklahoma h $27.43 $56.34 Texas $24.09 $53.89 Southeast $23.94 $53.44 Iniana/Iowa $30.48 $63.10 Preconitione i $22.73 $54.14 Grass $22.08 $54.91 Wheat $21.63 $53.05 Feelot 2 j $28.61 $53.74 a Base values in the performance sheet set to the means of the ata, an ummy variables at their efault. b Percent treate was change by its mean plus one stanar eviation c Percent mortality was change to a value equal to its mean plus one stanar eviation. Average in-weight was change to a value equal to its mean plus one stanar eviation. e Average out-weight was change to a value equal to its mean plus one stanar eviation f Mixe an heifers are ummy variables compare to the efault, which was steers. g Quarters 2-4 are ummy variables compare to the efault, which was quarter 1. h Oklahoma, Texas, Southeast, an Iniana/Iowa are ummy variables for origin of cattle compare to the efault, which was Kansas. i Preconitione, grass, an wheat are ummy variables compare to the efault sale barn cattle. j Feelot 2 is a ummy variable; efault is cattle fe in feelot 1. k Average aily gain is pouns of gain per hea per ay. 2. Bryant LK, Perino LJ, Griffin DD, Doster AR, Wittum TE: A metho for recoring pulmonary lesions of beef calves at slaughter, an the association of lesions with average aily gain. Bov Pract 33: , Ewars AJ: Respiratory iseases of feelot cattle in central USA. Bov Prac 30:5-7, Garner BA, Northcutt SL, Dolezal HG, Gill DR: Factors influencing profitability of feelot steers. Oklahoma State University Animal Science Research Report. 1996, No P-951, pp Garner BA, Dolezal HG, Owens FN, Bryant LK, Nelson JL, Schutte BR, Smith RA: Impact of health on profitability of feelot steers: Oklahoma State University Animal Science Research Report. 1998, No P- 965, pp Garner BA, Dolezal HG, Bryant LK, Owens FN, Smith RA: Health of finishing steers: Effects on performance, carcass traits, an meat tenerness. J Anim Sci 77: , Guillermo FG, Berg JL: Efficacy of a fee aitive antimicrobial combination for improving feelot cattle performance an health. Can Vet J 36: , Langemeier M, Schroeer T, Mintert J: Determinants of cattle finishing profitability. Southern J Ag Economics 24:41-47, Lawrence JD, Wang Z, Loy D: Elements of cattle feeing profitability in miwest feelots. J Ag an Applie Econ 31: , Loneragan GH, Dargatz DA, Morley PS, Smith MA: Trens in mortality ratios among cattle in US feelots. J Am Vet Me Assoc 219: , Schroeer TC, Albright ML, Langemeier MR, Mintert J: Factors affecting cattle feeing profitability. J Amer Society of Farm Managers an Rural Appraisers 57:48-54, Smith RA, Stokka GL, Raostits OM, Griffin DD: Health an prouction management in beef feelots, in Raostits OM (e): Her Health Foo Animal Prouction Meicine, e 3. Philaelphia: WB Sauners Co, pp , Stuenmun AH: Using Econometrics A Practical Guie, e 4. Boston: Aison Wesley Longman, Inc, Texas A&M University Extension Animal Science. TAMU Ranch to Rail: Annual Ranch to Rail Summaries USDA Part III: Health management an biosecurity in U.S. feelots, 1999: USDA: APHIS:VS, CEAH, National Animal Health Monitoring System. Fort Collins, CO. #N , Vogel GJ, Parrot C: Mortality survey in feeyars: the incience of eath from igestive, respiratory, an other causes in feeyars on the great plains. Comp Contin E Pract Vet 16: , Wittum TE, Woollen NE, Perino LJ, Littleike ET: Relationship among treatment for respiratory tract isease, pulmonary lesions evient at slaughter, an rate of gain in feelot cattle. J Am Vet Me Assoc 209: , THE BOVINE PRACTITIONER VOL. 40, NO. 2