@article{rogers_mcdaniel_dentine_funk_1989, title={GENETIC CORRELATIONS BETWEEN SURVIVAL AND LINEAR TYPE TRAITS MEASURED IN 1ST LACTATION}, volume={72}, ISSN={["1525-3198"]}, DOI={10.3168/jds.S0022-0302(89)79135-9}, abstractNote={Abstract Sire evaluations for 173 sires by BLUP for survival to 48, 54, 84 mo, and age at last record from unregistered daughters were correlated with proofs for 14 primary linear type traits and PD type computed by the Holstein Association of America. Progeny tests for type traits were based on first available scores. Genetic correlations between survival or survival adjusted for milk yield and early culling and most type traits were low or antagonistic. Body characteristics especially had low or negative correlations. When the effects of milk yield were removed, foot angle and udder characteristics (except rear udder) had positive genetic correlations with survival. Udder depth and teats rear view had the highest genetic correlations with survival adjusted for yield (near .25). Correlations between udder traits and survival to 84 mo were only slightly reduced by removing the effects of early culling in addition to yield. This suggests that udder characteristics may be useful in selection to reduce involuntary culling even if culling in first lactation is known. In addition to milk yield, selection based on udder depth and perhaps teat placement and foot angle may be justified in commercial dairy cattle.}, number={2}, journal={JOURNAL OF DAIRY SCIENCE}, author={ROGERS, GW and MCDANIEL, BT and DENTINE, MR and FUNK, DA}, year={1989}, month={Feb}, pages={523–527} }
 @article{rogers_mcdaniel_dentine_norman_1989, title={RELATIONSHIPS AMONG PROOFS FOR SURVIVAL, CULLING, AND YIELDS IN 1ST AND LATER LACTATIONS}, volume={72}, ISSN={["1525-3198"]}, DOI={10.3168/jds.S0022-0302(89)79136-0}, abstractNote={Abstract Sire evaluations for survival to 84 mo and age at last record from unregistered cattle were regressed on combinations of the following: BLUP summaries for percent culled in first lactation (from unregistered cattle) and PD milk from all, first, later, and later minus first lactations. Correlations between sire summaries for survival and the other traits were all favorable. Of the yield variables, PD from later lactations had the largest correlations with the summaries for survival. Predicted Difference based on first lactations had a low correlation with survival to 84 mo. Partial regressions indicated that PD for yield in first lactation was of little value to predict survival rates after percent culled. Predicted Difference for yield in later lactations and the difference in PD (later minus first) were significant when fitted after percent culled. The difference in PD was significant when fitted along with percent culled and PD milk from all lactations. Low early culling, high later lactations, and large increases in yield from first to later lactations were associated with greater survival rates to older ages. Higher yields in later lactations may be associated with cows that are able to maintain their health.}, number={2}, journal={JOURNAL OF DAIRY SCIENCE}, author={ROGERS, GW and MCDANIEL, BT and DENTINE, MR and NORMAN, HD}, year={1989}, month={Feb}, pages={528–532} }
 @article{rogers_1989, title={Relationships among culling, net revenue, milk yield and type traits in dairy cattle}, volume={49}, number={7}, journal={Dissertation Abstracts International. B, Sciences and Engineering}, author={Rogers, G. W.}, year={1989}, pages={2431} }
 @article{rogers_mcdaniel_1989, title={THE USEFULNESS OF SELECTION FOR YIELD AND FUNCTIONAL TYPE TRAITS}, volume={72}, ISSN={["1525-3198"]}, DOI={10.3168/jds.S0022-0302(89)79096-2}, abstractNote={Abstract Udder depth, teat placement, foot angle, and milk yield measured in first lactation were evaluated in an index to improve a breeding goal consisting of milk yield and involuntary culling. Efficiencies of response for full and reduced indices were calculated for various economic values and genetic parameters from the literature. Sire and individual (based only on cow's performance) indices were calculated. Selection only for milk would result in 87 to 97% of the expected progress in the breeding goal when all four traits were included. Standardized b-values (index coefficients) for milk were about two to three times the sum of the standardized b-values for the type traits. Predicted response in the aggregate genotype was sensitive to genetic correlations between involuntary culling and type traits. Predicted response was insensitive to small changes in heritability for involuntary culling or changes in genetic correlations between milk and type traits. Selection on udder traits, foot angle, and production would result in only a small increase in efficiency above selection on production alone. However, these type traits may help reduce involuntary culling or limit correlated increases in involuntary culling associated with increased milk yield.}, number={1}, journal={JOURNAL OF DAIRY SCIENCE}, author={ROGERS, GW and MCDANIEL, BT}, year={1989}, month={Jan}, pages={187–193} }
 @article{rogers_vanarendonk_mcdaniel_1988, title={INFLUENCE OF INVOLUNTARY CULLING ON OPTIMUM CULLING RATES AND ANNUALIZED NET REVENUE}, volume={71}, ISSN={["1525-3198"]}, DOI={10.3168/jds.S0022-0302(88)79952-X}, abstractNote={Abstract Dynamic programming was used to make optimum insemination and culling decisions. Revenue depended on the sale of milk, calves, and cull cows. Costs were based on feed costs, health costs, replacement costs, housing costs, and interest. Conception probabilities, genetic improvement, variation in production, and repeatability of production and involuntary culling probabilities were considered when making the optimum decisions. Annualized net revenue, optimum culling rates, and the optimum average productive life were determined for various involuntary culling rates. Results indicated that involuntary culling probabilities have a large impact on annualized net revenue. Reducing involuntary culling rates by 2.9% (marginal involuntary culling rates by 20%) resulted in about $22 more net revenue per cow per year. Increasing average mature equivalent milk yield by 122 kg resulted in the same increase in net revenue. Value of lowering the overall rate of involuntary culling was not affected by assuming that higher yielding cows were more prone to culling for involuntary reasons; however, optimum voluntary culling patterns were altered. Less intense culling in young cows was optimum when compared with the situation where the probability of involuntary culling was independent of production. Management and breeding policies should be directed toward increasing milk yield and decreasing the causes of involuntary culling.}, number={12}, journal={JOURNAL OF DAIRY SCIENCE}, author={ROGERS, GW and VANARENDONK, JAM and MCDANIEL, BT}, year={1988}, month={Dec}, pages={3463–3469} }
 @article{rogers_vanarendonk_mcdaniel_1988, title={INFLUENCE OF PRODUCTION AND PRICES ON OPTIMUM CULLING RATES AND ANNUALIZED NET REVENUE}, volume={71}, ISSN={["1525-3198"]}, DOI={10.3168/jds.S0022-0302(88)79951-8}, abstractNote={Abstract Dynamic programming was used to make optimum insemination and culling decisions for a dairy enterprise. Monthly costs and revenues for cows were calculated from milk and fat yields, calf values, feed costs, veterinary costs, housing and equipment costs, and interest. Cows were described in the dynamic programming model by lactation number, month in lactation, milk production during the present and previous lactations, and time of conception. The model considered variation in milk yield, replacement heifer costs, carcass values, involuntary culling, genetic improvement, conception rates, semen costs, and interest. Prices and parameters were chosen to represent the Holstein population in the US. Optimum average yearly culling rate was about 25% (optimum average herd life was 47.8 mo) and the yearly annuity of net revenue for a replacement heifer over a 15-yr planning horizon was $443 in the base situation. Various average mature equivalent yields, replacement heifer prices, milk prices, and feed prices were used in a sensitivity analysis. The yearly annuity of net revenue was sensitive to changes in all these parameters. Milk yield, milk prices, and feed prices had major effects on yearly annuity. Optimum culling decisions were sensitive to changes in replacement heifer prices. Average mature equivalent milk yield, milk price, and feed price had small effects on culling.}, number={12}, journal={JOURNAL OF DAIRY SCIENCE}, author={ROGERS, GW and VANARENDONK, JAM and MCDANIEL, BT}, year={1988}, month={Dec}, pages={3453–3462} }