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D T Galligan

Publications and source records attributed to D T Galligan.

At least 19 recordsLinked to original sources
PubMed2004

An economic spreadsheet model to determine optimal breeding and replacement decisions for dairy cattle.

The aim of this paper is to describe a user-friendly spreadsheet culling model that was constructed to support economical, optimal breeding and replacement decisions on dairy farms. The model was based on the marginal net revenue technique. Inputs for the model can be entered for specific farm conditions, and the output is easily accessible. In the model, the retention pay-off (RPO) value of individual dairy cows was calculated. The RPO value of a cow is equal to the total additional profits that a producer can expect from trying to keep the cow until her optimal age, taking into account the changes of involuntary removal compared with her immediate replacement. To calculate the RPO values, the future production, revenues, and costs of dairy cows at different levels of milk production with different numbers of days open (DO) were determined. Furthermore, the ranges of carcass value, calf revenues, and the range of involuntary disposal rates of cows within and across lactations were taken into account. To illustrate the model, parameters in the model were chosen to represent a typical Holstein dairy herd in Pennsylvania. The results of this model are very comparable with earlier, more complex models that are more difficult to use on the farm. In addition to using the RPO values to evaluate the decision to breed or replace a cow, the costs per additional DO were estimated. Early conception was most profitable with the costs per additional DO varying from $0 to more than $3/d. The model can be used as a decision-supporting tool for producers, extension personnel, veterinarians, and consultants. In addition, researchers, economists, and government organizations can use the model to determine the costs of culling dairy cows in a disease control program. The model and manual are available at http://cahpwww.vet.upenn.edu/software/econcow.html.

Aging↗
PubMed2004

The use of integer programming to select bulls across breeding companies with volume price discounts.

Optimization programs are currently used to aid in the selection of bulls to be used in herd breeding programs. While these programs offer a systematic approach to the problem of semen selection, they ignore the impact of volume discounts. Volume discounts are discounts that vary depending on the number of straws purchased. The dynamic nature of volume discounts means that, in order to be adequately accounted for, they must be considered in the optimization routine. Failing to do this creates a missed economic opportunity because the potential benefits of optimally selecting and combining breeding company discount opportunities are not captured. To address these issues, an integer program was created which used binary decision variables to incorporate the effects of quantity discounts into the optimization program. A consistent set of trait criteria was used to select a group of bulls from 3 sample breeding companies. Three different selection programs were used to select the bulls, 2 traditional methods and the integer method. After the discounts were applied using each method, the integer program resulted in the lowest cost portfolio of bulls. A sensitivity analysis showed that the integer program also resulted in a low cost portfolio when the genetic trait goals were changed to be more or less stringent. In the sample application, a net benefit of the new approach over the traditional approaches was a 12.3 to 20.0% savings in semen cost.

Animals↗
PubMed2003

Optimizing replacement of dairy cows: modeling the effects of diseases.

We modified an existing dairy management decision model by including economically important dairy cattle diseases, and illustrated how their inclusion changed culling recommendations. Nine common diseases having treatment and veterinary costs, and affecting milk yield, fertility and survival, were considered important in the culling decision process. A sequence of stages was established during which diseases were considered significant: mastitis and lameness, any time during lactation; dystocia, milk fever and retained placenta, 0-4 days of lactation; displaced abomasum, 5-30 days; ketosis and metritis, 5-60 days; and cystic ovaries, 61-120 days. Some diseases were risk factors for others. Baseline incidences and disease effects were obtained from the literature. The effects of various disease combinations on milk yield, fertility, survival and economics were estimated. Adding diseases into the model did not increase voluntary or total culling rate. However, diseased animals were recommended for culling much more than healthy cows, regardless of parity or production level. Cows in the highest production level were not recommended for culling even if they contracted a disease. The annuity per cow decreased and herdlife increased when diseases were in the model. Higher replacement cost also increased herdlife and decreased when diseases were in the model. Higher replacement cost also increased herdlife and decreased the annuity and voluntary culling rate.

Animal Husbandry↗
PubMed2001

A survey of dairy farming in Pennsylvania: nutrient management practices and implications.

A survey was conducted to collect information on nutrient management practices on dairy farms in south-central Pennsylvania. Of the 994 responding farms, the average farm consisted of 64 lactating cows, 10 dry cows, 41 heifers, and 17 calves with 69.7 ha of tillable land. Manure from lactating cows was mainly collected on a daily basis (84% of the farms) and stored as slurry or liquid (73%), while dry cow and heifer manure was collected weekly or less frequently (69 and 85% of the farms) and stored as solid stack or bedded pack (67 and 82%). Manure utilization featured consistent use of on-farm spreading, with limited incorporation, to corn or small grain fields before planting. Spreading on perennial forages or pasture was also common. Irrigation or injection of manure occurred on less than 5% of the farms. Only 20% of the farms reported manure nutrient testing, contrasting to over 90% for soil testing. Farm advisors and their services can be of vital importance in helping producers make conscientious management decisions for enhanced nutrient utilization. For example, ration balancing involved the services of feed and mineral sales representatives (85% of the farms), independent consultants (12%), and veterinarians (5%). Manure nutrient crediting to determine manure application rates was made by fertilizer dealers (40%), crop advisors and independent consultants (31%), and others. Nutrient management strategies and efforts must address the specific needs of farms with different animal densities and nutrient balances in order to be effective and applicable on the majority of farms.

Agriculture↗
PubMed2000

Optimization of dairy heifer management decisions based on production conditions of Pennsylvania.

We used a dynamic programming model to determine optimum rearing decisions of dairy replacements. Heifers were described in the model by age, season, body weight, pregnancy state, and prepubertal growth rate. Prices and parameters were chosen to represent the dairy population of Pennsylvania. We calculated monthly costs and revenues from calf value, feed costs, veterinary costs, semen costs, carcass value, and full-grown heifer value. The model considered a stochastic variation in the onset of puberty, conception, involuntary disposal, and a seasonal variation in the prices of calves, heifers, and feed. Based on a critical prepubertal average daily gain of 0.9 kg/d and a maximum achievable postpubertal growth rate of 1.1 kg/d, the optimum practice resulted in an average age at first calving of 20.5 mo at a body weight of 563 kg. Discounted net returns equaled $107 per heifer per year. The optimum rearing practice was not sensitive to seasonal variation in prices. Nevertheless, the economic results per season of birth varied considerably; the highest income per heifer was obtained from heifers born in December ($142/yr), whereas those born in May yielded the lowest ($100/yr). Sensitivity analyses demonstrated a considerable influence of growth rate restrictions and variation in reproductive performance on both the optimal rearing practices as the expected net returns.

Animal Feed↗
PubMed1999

The economics of optimal health and productivity in the commercial dairy.

Dairy production practices are changing; in order to remain viable, producers must optimise the health and productivity of dairy herds in economic terms. Health care is important in economic terms because disease can substantially reduce the productivity of individual animals. Preventive disease control programmes can thus result in economic gains for the dairy producer. The author describes new approaches to preventing postpartum diseases and dealing with fertility problems which can result from these diseases. Other aspects of dairy production are also changing, employing new technologies where these are judged to be profitable. Innovations include: the use of bovine somatotropin; systematic breeding/culling programmes; new mathematical modelling techniques to determine optimum feed composition and to define optimal growth levels for accelerated heifer-rearing programmes; the use of computers to collect, store and analyse data on animal production and health; and semen selection programmes. Increasing awareness of bio-security is also vital, not least because of the large investment present in dairy herds. Whatever practices are employed, they must offer economic returns to producers that compete with alternative uses of capital. Optimal levels of disease control must be determined for a particular production situation, taking into account not only the economic health of the producer, but also the well-being of the animals.

Animals↗
PubMed1997

Milk production and reproductive performance in dairy cows given bovine respiratory syncytial virus vaccine prior to parturition.

OBJECTIVE: To assess the effect of vaccination against bovine respiratory syncytial virus on milk production, reproductive performance, and health in lactating dairy cows. DESIGN: Prospective randomized block design. ANIMALS: 385 Holstein dairy cows and heifers. PROCEDURE: Cows were grouped by lactation number, season of calving, and previous mature equivalent 305-day milk production (where appropriate). Prior to parturition, cows and heifers were randomly assigned to be vaccinated i.m. against infectious bovine rhinotracheitis, bovine viral diarrhea, and parainfluenza 3 viruses by use of a three-way vaccine, or to be vaccinated against those viruses as well as bovine respiratory syncytial virus, using a four-way vaccine. Milk production was measured daily through 305 days of lactation. Reproductive and medical records were reviewed to obtain insemination dates and record medical problems of cows in each vaccine treatment group. RESULTS: Compared with the three-way vaccine, administration of the four-way vaccine was associated with higher milk production (1.39 kg [3.06 lb] more milk/d) in first-parity cows during the first 21 weeks of lactation. Vaccination did not have any effect on milk production after the first 21 weeks of lactation in cows of any parity. Conception rates at first insemination were higher for four-way vaccinated first-parity cows than for three-way vaccinated first-parity cows (54.6 vs 32.7%). Compared with second-parity cows that received the three-way vaccine, first insemination conception rate was improved for second-parity cows vaccinated with the four-way vaccine (28.9 vs 47.8%, respectively). In cows of third or greater parity, first insemination conception rate was not different between the 2 vaccine treatment groups. CLINICAL IMPLICATIONS: Vaccination of heifers against bovine respiratory syncytial virus prior to partrition may increase milk production and first insemination conception rates.

Animals↗
PubMed1997

Technical and economic models to support heifer management decisions: basic concepts.

To maximize herd profits, dairy farmers are faced with the complex dilemma of minimizing costs that are associated with rearing heifers while ensuring or enhancing lifetime economic productivity. Decisions about heifer management interact with underlying biological aspects of growth, thereby influencing future profitability. A thorough understanding of these biological interactions is lacking. Studies based on models could be useful in the evaluation of various rearing strategies. Currently available models for dairy cattle primarily focus on the dairy cow. In a dairy farm production system, management decisions concerning the rearing of livestock and the replacement of dairy cows strongly influence each other. In a model that describes the dairy herd as a multiple-component system, opportunity is greater to coordinate rearing and replacement policies. Expected benefits of such a model are discussed.

Animals↗
PubMed1997

Estimation of interdependence among quarters of the bovine udder with subclinical mastitis and implications for analysis.

Interdependency among udder quarters with subclinical mastitis was evaluated on 150 farms using a total of 35,828 udder quarters. The occurrence of high somatic cell count (SCC) (> 250,000 cells/ml) in 0, 3, and 4 quarters occurred at a higher rate than would be expected based on independence of the quarters. For all bacterial species, intramammary infection in 0, 2, 3, or 4 quarters of the same cow occurred at a higher rate than would be expected based on independence of the quarters. Intramammary infection and high SCC were found less often in front quarters than in rear quarters. High SCC and intramammary infection occurred more often in right front quarters than in left front quarters. High SCC in diagonal quarters occurred at a lower rate than expected. Corynebacterium bovis, Streptococcus agalactiae, and Staphylococcus aureus had the highest intraclass correlation within herd. Streptococcus uberis had a very low intraclass correlation within herd. The intraclass correlation within cow for the natural logarithm of SCC was 0.47. Corynebacterium bovis and Strep. agalactiae had the highest intraclass correlation within cow, and Streptococcus dysgalactiae had the lowest. Analytical methods were proposed to manage the problem of interdependence and its effect on the design or evaluation of field studies on subclinical mastitis.

Animals↗
PubMed1996

Responses of dairy cows supplemented with somatotropin during weeks 5 through 43 of lactation.

Beginning at wk 5 of lactation, 136 cows (34 per treatment) were supplemented daily for 38 wk with 0, 10.3, 20.6, or 41.2 mg of recombinantly derived bST monomer. Cows were obtained from University of Kentucky, University of Minnesota, University of Pennsylvania, and The Ohio State University. Nine cows (4 at 0 mg/d, 1 at 10.3 mg/d, 1 at 20.6 mg/d, and 3 at 41.2 mg/d) did not complete the experiment because of health problems. Data from these cows were included in the reproduction and health databases but not in the production database. Cows supplemented with bST produced more milk, consumed more feed, had lower rates of BW gain, and had improved efficiencies of milk production (conversion of feed and NEL to milk). Additional increases in productivity were modest at 20.6 and 41.2 mg/d versus productivity at 10.3 mg/d of bST. Concentrations of fat, protein, and TS in milk were unaffected. At 10.3 mg/d, bST did not adversely affect reproduction or health.

Animal Nutritional Physiological Phenomena↗
PubMed1995

Application of linear programming in bull selection for a dairy herd.

Approximately 70% of dairy cows are inseminated with semen from bulls provided by commercial artificial insemination centers. To help producers in the selection process, artificial insemination centers publish information regarding production and type traits associated with each bull. Producers must decide from these lists which bulls to use, how often they are to be used, and to which cows they should be allocated. The bulls selected have a direct effect on cost of semen for the herd and genetic improvement in production of future generations. In general, producers' goals are to replace poor genes through strategic culling (not breeding certain cows) with better genes through semen purchases in an economically efficient manner. The cost of semen, however, is realized immediately, whereas economic returns from the traits selected are dependent on the realization of future cash flows. Higher production returns are needed to justify using more expensive bulls. The purposes of the study reported here were to examine the bull selection portfolio of a 450-cow commercial dairy herd in southeastern Pennsylvania and to use linear optimizing programming to select a genetically similar group of bulls at a much lower cost than that the producer had been using. This approach of dominant decision-making can be generalized and implemented for various dairy from conditions.

Animals↗
PubMed1994

Principal descriptors of body condition score in Holstein cows.

The objective of this study was to assess objectively the ability of observers to assess body condition of dairy cows. Four observers independently assigned a body condition score (five-point scale, .25 increments) and described the appearance of seven body regions of 225 Holstein cows. Areas described were the thurl region, ischial and ileal tuberosities, ilio-sacral and ischio-coccygeal ligaments, transverse processes of the lumbar vertebrae, and spinous processes of the lumbar vertebrae. An absolute body condition score was designated for each cow based on the modal body condition score for all observers. If there was no modal body condition score, the mean score was used for the absolute body condition score. Statistical analysis of principal components was used to examine the relationship between body region description and absolute body condition score. Descriptions of body regions were highly correlated across all absolute body condition scores. Four principal component vectors explained 83.6% of the variation of the body region correlation matrix. The first principal latent vector accounted for 55% of the variation and was uniformly correlated with all body regions. Analysis of variance of first principal latent vector as the dependent variable and absolute body condition score as the class variable indicated that body condition could be separated into .25 units between 2.5 and 4.0, inclusively. Below 2.5 and > 4.0, body condition could only be separated by .5 units. Distinct changes in specific body regions were associated with change in absolute body condition score. Observers agreed with the absolute score 58.1% of the time, deviating by .25 units 32.6% of the time. A body condition score can be given to a cow based on principal descriptors of specific body regions between 2.5 and 4.0 by .25 units.

Adipose Tissue↗
PubMed1994

Blood lead levels of wild raccoons (Procyon lotor) from the eastern United States.

We analyzed 161 raccoon (Procyon lotor) blood samples obtained from New Jersey (n = 109), rural Pennsylvania (n = 29) and laboratory confined animals (n = 23) in the USA for lead content; we found significantly higher levels in the New Jersey raccoons (mean = 4.4 micrograms/dl, SE = 2.9). There was no difference between the lead levels of raccoons from the other two groups (mean = 2.6, SE = 0.5 and mean = 2.5, SE = 0, respectively).

Animals↗
PubMed1993

Diagnosis and prediction of cervical vertebral malformation in thoroughbred foals based on semi-quantitative radiographic indicators.

Over a period of 5 years on a central Kentucky Thoroughbred stud farm 132 foals were evaluated for the presence of cervical vertebral malformation (CVM). Lateral cervical vertebral radiographs were obtained on 70 standing foals. These radiographs were evaluated semi-quantitatively and scored numerically for the presence of stenosis of the vertebral canal, enlarged physeal growth plates, caudal extension of the dorsal border of the orifice of the vertebral canal, angular fixation, delayed ossification of bone and degenerative joint disease. From these scores a total CVM score was given for each set of radiographs. All foals were repeatedly examined for clinical signs of neurological disease. Foals with no clinical signs of CVM had maximal total CVM scores (mean +/- sd) of 5.7 +/- 2.8 and foals affected with CVM had maximal total CVM scores of 17.0 +/- 2.8. Determination of the total CVM score was non-invasive, inexpensive and a very accurate procedure for predicting and diagnosing the presence of CVM in Thoroughbred foals up to 1 year of age.

Animals↗
PubMed1993

Immunohistochemical study to demonstrate Sarcocystis neurona in equine protozoal myeloencephalitis.

A 5-year (1985-1989) retrospective immunohistochemical study was conducted using an avidin-biotin complex (ABC) immunoperoxidase method to demonstrate Sarcocystis neurona in histologically suspect cases of equine protozoal myeloencephalitis (EPM). Primary antibodies against S. neurona and S. cruzi were utilized for the ABC technique. The findings were compared with those from cases in which the organisms were detected by examination of hematoxylin and eosin (HE)-stained neuronal sections. HE-stained sections detected the presence of the organisms in 20% of the suspect cases; whereas the ABC technique confirmed the presence of S. neurona in 51% and 67% of the cases by S. neurona and S. cruzi antibodies, respectively. A review of clinical case histories showed that 21/47 (45%) of the EPM horses with parasites in the tissue sections had prior treatment with antiprotozoal drugs and/or steroids. Using the test results of S. neurona and S. cruzi as a standard reference, HE test sensitivity based on examination of up to 30 neuronal sections per case was only 25%, and test specificity was 91%.

Animals↗
PubMed1993

Serum urea nitrogen and conception rate: the usefulness of test information.

Total of 627 AI in 332 Holstein cows in nine herds were used to examine the relationship between serum urea N and conception rate. Cows were assigned randomly to one of three isocaloric diets varying in protein degradability and content. The AI occurred from 50 to 150 DIM. Mean serum urea N for each cow from 50 to 150 DIM was used to examine conception rate and serum urea N. The clinical interpretation of serum urea N on conception rate is evaluated using Bayes theorem from two approaches (dichotomization vs. continuous). Test information resulting from dichotomization of serum urea N into high and low categories (maximizing the average of test sensitivity and specificity) is compared with likelihood ratio approaches allowing a continuous measure. Likelihood ratio test indicates that conception rate decreases with serum urea N of > 14.9 mg/dl, but dichotomized test suggests that the decrease does not occur until serum urea N is > 20 mg/dl.

Animals↗
PubMed1991

New approaches to nutritional monitoring.

This article discusses new and innovative methods that can be used in the field to assess the economic value of ingredients in the production system. Methods to evaluate and monitor milk production responses are considered.

Animal Feed↗