About

Chad Dechow is a Professor of Dairy Cattle Genetics at the Pennsylvania State University. His research focuses on the genetics of dairy cattle, contributing to the understanding and improvement of dairy cattle traits through genetic analysis. As a faculty member, he is involved in advancing the sciences related to animal genetics, with an emphasis on dairy cattle, and plays a key role in research that supports genetic improvement programs in dairy production.

Research topics

• Animal science
• Biology
• Medicine
• Genetics
• Endocrinology
• Agricultural science
• Physics
• Agronomy
• Food science
• Business
• Biotechnology
• Demography
• Internal medicine

Selected publications

• Organic calf growth associations with sire breed and with milk and component yield in later life

  Organic Agriculture · 2025-07-04

  articleOpen accessSenior author

  Abstract A relationship has been established between calf growth rate and milk production in conventional dairy herds, but not in organic herds. This study was designed to evaluate the effect of sire breed on body weight (BW) and average daily gain (ADG) of organic calves and to evaluate the effect of calf BW and ADG on first lactation production. Records from 114 calves with 944 BW from 1 to 9 weeks of age were retained for determination of BW in week 1 (BW1), BW in week 8 (BW8), and average daily gain (ADG). First lactation production records (305-d mature equivalent milk (M-305), 305-d fat (F-305), 305-d protein (P-305), average 305-d somatic cell score (SCS), fat %, protein %, and energy corrected milk (ECM)) were available from 83 animals. Calves were of 5 different sire breeds: Holstein (HO, N = 52), Jersey (JE, N = 11), Montbeliarde (MO, N = 9), Viking Red (VR, N = 7), and others (O, N = 4). MO, VR and HO sired calves were heavier and had higher ADG (0.76 kg/d, 0.73 kg/d and 0.71 kg/d, respectively) than JE sired (0.65 kg/d) calves. Regression on BW1 and BW8 were associated with increased M-305 (34.36 kg and 23.12 kg, respectively), F-305 yield (1.07 kg and 0.63 kg, respectively),P-305 (0.93 kg and 0.63 kg, respectively), and ECM (31.53 kg and 20.01 kg, respectively). Moreover, we found that each kg increase in ADG was associated with a 1580.39 kg M-305 increase during first lactation. These results indicate that the sire breed was associated with pre-weaning growth of dairy calves and higher growth was associated with increased production in the first lactation in organic herds.

  PublisherOA PDFDOI

• Predictive ability of a commercial mixed-breed genomic test for feedlot performance and carcass traits of beef × Holstein steers

  Journal of Animal Science · 2025-01-01

  articleOpen accessSenior author

  Genomic tests are marketed as a method to appraise cattle value prior to feedlot entry. We aimed to evaluate the use of a commercial, multi-breed genomic test to predict terminal production characteristics of beef × Holstein steers. Phenotypes of feedlot performance and carcass characteristics were evaluated in beef × Holstein steers (n = 259) sired by 8 beef breeds. Steers were genotyped with Igenity Beef (Neogen Corporation, Lansing, MI), which ranks cattle for individual traits and by selection indexes on a scale of 1 to 10. Trait rankings were converted to molecular breeding values (MBV) derived from genotype. Expected progeny differences (EPD) of each steer's sire were accessed from their respective breed associations. U.S. Meat Animal Research Center across-breed adjustments for beef cattle were applied to growth and carcass sire EPD for all cattle except for the 11 Wagyu-sired steers (n = 248 steers with sire EPD). Breed-adjusted sire EPD and MBV of traits were correlated with associated phenotypes of beef × Holstein steers and phenotypes were regressed on sire EPD and MBV. Sire EPD and MBV of yearling weight (YW) and hot carcass weight (HCW) were positively associated with initial and final feedlot body weight, respectively. The MBV of average daily gain (ADG) was not associated with phenotypic ADG, though greater derived sire EPD of ADG was associated with greater ADG and dry matter intake (DMI). The MBV of residual feed intake (RFI) was associated with DMI (P = 0.02) but not RFI or gain-to-feed ratio. Each kg of RFI predicted by MBV resulted in 0.31 kg greater ADG (P < 0.01), suggesting that MBV of RFI in beef × Holstein steers are not independent of the rate of gain. For each kg of HCW predicted by MBV and sire EPD carcasses were 0.52 and 0.80 kg heavier (P < 0.01). Neither sire EPD nor MBV of ribeye area and backfat thickness were related to the corresponding phenotypes of beef × Holstein carcasses (P > 0.05). Both MBV and sire EPD of marbling score were strong predictors of marbling score and intramuscular fat content (P < 0.05). Tenderness MBV accurately predicted tenderness of the longissimus muscle of beef × Holstein progeny (P < 0.01). Igenity Beef Terminal Index ranking was associated with greater feedlot profitability (P = 0.03), but marbling MBV and sire EPD were more strongly associated with feedlot net profit (P < 0.01). Breed-adjusted sire EPD performed similarly to Igenity Beef MBV in predicting growth performance, carcass characteristics, and net profit of beef × Holstein steers.

  PublisherOA PDFDOI

• Association of sire net merit with farm profitability for Minnesota dairy farms

  Journal of Dairy Science · 2025-05-09

  articleOpen access

  Lifetime net merit (NM) is a genetic selection index based on the weighted average of economically relevant traits to the dairy cow. It is measured in dollars as the expected lifetime profitability of a cow. The objective of this study was to evaluate the association between average sire net merit management decisions and farm profitability for Minnesota dairy farms from 2012 to 2018 using a unique herd-year dataset (n = 227) containing production data for dairy cows, sire NM, and the respective financial information for the farm. We extended the net merit and profitability analysis by analyzing the individual net merit traits that might be driving profitability. Ordinary least squares models were estimated for 4 profitability measures: operating profit margin, rate of return on assets (RROA), net farm income (NFI), and NFI per cow. Results indicated that herd sire net merit has a positive and significant relationship with RROA, NFI, and NFI per cow. A $100 increase in the herd's sire net merit was associated with an 18% (0.6 percentage point) increase in RROA, $12,100 increase in NFI, and $87 increase in NFI per cow, all else equal. Although the genetic association was significant, it explained 3.62% or less variation, highlighting that herd genetics were not the primary factor driving profitability. A few of the individual net merit traits held a significant relationship with profit, but most of the individual net merit traits did not. We concluded that it is not individual traits that influenced profitability, but rather the collective group of traits. The results from this study suggested that decisions related to genetic selection are valuable for a farm's profit and confirmed that when selecting genetics, it was most effective to select sires based on an economic index, rather than specific traits.

  PublisherOA PDFDOI

• The impact of sire breed on feedlot performance and carcass characteristics of beef × Holstein steers

  Translational Animal Science · 2024-01-01 · 2 citations

  articleOpen access

  Abstract Dairy herds are mating a portion of cows to beef cattle semen to create a value-added calf. Objectives of this study were to compare the feedlot performance and carcass characteristics of beef × Holstein steers by breed when sires represented bulls with commercially available semen. Three groups of single-born, male calves (n = 262) born to Holstein dams on 10 Pennsylvania dairies were sourced during 3 yr. Steers were sired by seven beef breeds: Angus, Charolais, Limousin, Hereford, Red Angus, Simmental, and Wagyu. Steers were picked up within a week of age and raised at two preweaned calf facilities until weaning (8 ± 1 wk of age) under similar health and management protocols. Steers were then transported to a commercial calf growing facility where they were managed as a single group until 10 ± 2 mo of age when they were moved to be finished at the Pennsylvania Department of Agriculture’s Livestock Evaluation Center feedlot. Groups of steers were selected for slaughter based on body weight. Carcass characteristics were evaluated by trained personnel and a three-rib section of the longissimus muscle (LM) was collected from each carcass for Warner-Bratzler shear force (WBSF) evaluation and intramuscular fat determination. Steers sired by all sire breeds except for Limousin had greater average daily gain (ADG; 1.62 to 1.76 kg/d) than Wagyu × Holstein steers (1.39 kg/d; P &amp;lt; 0.05). Angus-sired steers had an 8.6% greater ADG than Red Angus-sired steers (P &amp;lt; 0.05). Angus, Charolais (1.73 kg/d), and Simmental-sired steers (1.68 kg/d) also had greater ADG than Limousin-sired steers (1.55 kg/d; P &amp;lt; 0.05). Wagyu × Holstein steers spent 5 to 26 more days on feed (P &amp;lt; 0.05) than Limousin × Holstein, Simmental × Holstein, Angus × Holstein, and Charolais × Holstein steers. Angus and Charolais-sired steers were also on feed for 19 and 21 d fewer, respectively, than Limousin-sired steers (P &amp;lt; 0.05). Red Angus-sired steers had greater marbling scores than Simmental and Limousin-sired steers and Angus and Charolais-sired steers had greater marbling scores than Limousin-sired steers (P &amp;lt; 0.05). Angus, Limousin, and Hereford-sired steers produced the most tender LM as evaluated by WBSF; Angus-sired carcasses (3.82 kg) were more tender than Charolais (4.30 kg) and Simmental-sired carcasses (4.51 kg; P &amp;lt; 0.05). Limousin and Hereford-sired steers (3.70 and 3.83 kg, respectively) also had more tender steaks than Simmental-sired steers.

  PublisherOA PDFDOI

• Effects of genetic and environmental trends from 1970 to 2020 on farm efficiency estimated with a whole-farm modeling system

  Journal of Dairy Science · 2024-09-17 · 2 citations

  articleOpen access1st authorCorresponding

  <h2>ABSTRACT</h2> The objectives of this study were to evaluate associations of genetic change, cow management and nutrition, inbreeding, and crop yields from 1970 to 2020 with measures of production and economic efficiency according to a whole-farm model, and to evaluate effects of genetic change in individual traits on economic efficiency in comparison to expectations from economic selection indexes. Genetic and phenotypic performance metrics for Holsteins from 1970 and 2020 were retrieved and input into the Integrated Farm System Model (IFSM) for a 7,000-cow Texas herd and a 50-cow Pennsylvania grazing herd. Crop yields estimates from 1970 and 2020 were retrieved, and farm hectarage was altered so that forage and energy concentrate requirements were met through farm production; likewise, scenarios evaluating effects of atmospheric CO₂ fertilization (CO₂F) on crop yield were evaluated by altering farm hectarage. For single traits that could be dynamically modeled by IFSM, performance shifts and resulting change in product prices or management expenses were added to 1970 base models. Economic efficiency was evaluated as the per-cow return to management and unpaid factors as compared with 1970 base models. As averaged across state scenarios, gains in economic efficiency were +$945 and −$76 for additive genetic and inbreeding effects, respectively, for a total gain from genetic change of +$869. Genetic gain in fat yield (+$549) and protein yield (+$524) were responsible for most of the genetic gain, whereas milk yield (−$128) and increased cow BW (−$129) depressed economic efficiency. Genetic change in productive life had a smaller effect (+$44) than predicted unless heifers were purchased and at double the default value. Gains due to cow management and nutrition increased efficiency by +$666 and crop yield increased efficiency by +$711, of which +$371 was attributed to CO₂F across scenarios. Whole-farm DM efficiencies derived as the ratio of fat- and protein-corrected milk yield to DMI increased from 0.82 (PA) and 0.97 (TX) in 1970 to 1.20 in 2020 and could be higher if farms reduce the size of their replacement herd by producing beef calves. The landmass required in 2020 was 63% and 78% of the 1970 requirement for Texas and Pennsylvania, respectively. Changes in cow genetic merit, management and nutrition, and crop yields have all increased the economic and environmental sustainability of milk production, and systems such as IFSM could be a useful tool to help inform economic selection indices.

  PublisherOA PDFDOI

• New mutation within a common haplotype is associated with calf muscle weakness in Holsteins

  Journal of Dairy Science · 2024-01-20 · 11 citations

  articleOpen accessSenior author

  A recessive haplotype resulting in elevated calf mortality but with apparent incomplete penetrance was previously linked to the end of chromosome 16 (78.7-80.7 Mbp). Genotype analysis of 5.6 million Holsteins indicated that the haplotype was common and traced back to 1952, with a key ancestor born in 1984 (HOUSA1964484, Southwind) identified from chip genotypes as homozygous for the suspect haplotype. Sequence data from Southwind (an affected calf) and the sire of the affected calf were scanned for candidate mutations. A missense mutation with a deleterious projected impact at 79,613,592 bp was homozygous in the affected calf and heterozygous in the calf's sire and Southwind. Sequence data available from the Cooperative Dairy DNA Repository for 299 other Holsteins indicated a 97% concordance with the haplotype and an 89% call rate. The exon amino acid sequence appears to be broadly conserved in the CACNA1S gene, and mutations in humans and mice can cause phenotypes of temporary or permanent paralysis analogous to those in calves with the haplotype causing muscle weakness (HMW). Improved methods for using pedigree to track new mutations within existing haplotypes were developed and applied to the haplotypes for both muscle weakness and Holstein cholesterol deficiency (HCD). For HCD, concordance of the gene test with its haplotype status was greatly improved. For both defects, haplotype status was matched to heifer livability records for 558,000 calves. For HMW, only 46 heifers with livability records were homozygous and traced only to Southwind on both sides. Of those, 52% died before 18 mo at an average age of 1.7 ± 1.6 mo, but that death rate may be underestimated if only healthier calves were genotyped. The death rate was 2.4% for noncarriers. Different reporting methods or dominance effects may be needed to include HMW and other partially lethal effects in selection and mating. Direct tests are needed for new mutations within existing common haplotypes because tracking can be difficult even with accurate pedigrees when the original haplotype has a high frequency.

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• Microbial composition, rumen fermentation parameters, enteric methane emissions, and lactational performance of phenotypically high and low methane-emitting dairy cows

  Journal of Dairy Science · 2023-07-20 · 47 citations

  articleOpen access

  This experiment was designed to investigate the relation of high and low methane-yield phenotypes with body weight (BW), dry matter intake (DMI), lactation performance, enteric CH4 emissions, and rumen fermentation parameters in lactating dairy cows. A total of 130 multi- and primiparous Holstein cows were screened for enteric CH4 emissions using the GreenFeed system (C-Lock Inc.). Out of these 130 cows, 5 were identified as phenotypically high (HM) and 5 as phenotypically low (LM) CH4 emitters. Cows in the LM group had lower daily enteric CH4 emissions than cows in the HM group (on average 346 vs. 439 g/d, respectively), lower CH4 yield (15.5 vs. 20.4 g of CH4/kg of DMI), and CH4 intensity (13.2 vs. 17.0 g of CH4/ kg of energy-corrected milk yield). Enteric emissions of CO2 and H2 did not differ between HM and LM cows. These 10 cows were blocked by parity, days in milk, and milk production, and were used in a 5-wk randomized complete block design experiment. Milk composition, production, and BW were also not different between LM and HM cows. The concentration of total volatile fatty acids in ruminal contents did not differ between CH4 phenotypes, but LM cows had a lower molar proportion of acetate (57 vs. 62.1%), a higher proportion of propionate (27.5 vs. 21.6%, respectively), and therefore a lower acetate-to-propionate ratio than HM cows. Consistently, the 16S cDNA analysis revealed the abundance of Succinivibrionaceae and unclassified Veillonellaceae to be higher in LM cows compared with HM cows, bacteria that were positively correlated with ruminal propionate concentration. Notably, Succinivibrionaceae trigger the formation of propionate via oxaloacetate pathway from phosphoenolpyruvate via Enzyme Commission: 4.1.1.49, which showed a trend to be higher in LM cows compared with HM cows. Additionally, LM cows possessed fewer transcripts of a gene encoding for methyl-CoM reductase enzyme compared with HM. In this study, low and high CH4-yield cows have similar production performance and milk composition, but total-tract apparent digestibility of organic matter and fiber fractions was lower in the former group of animals.

  PublisherOA PDFDOI

• Association between hyperketolactia and production in early-lactating dairy cows

  Journal of Dairy Science · 2023-09-09 · 3 citations

  articleOpen accessSenior author

  Study aims were to investigate associations of hyperketolactia (HYKL) status of Holstein dairy cows between 6 and 60 d in milk (DIM), defined by milk acetone (mACE) and β-hydroxybutyrate (mBHB) content, with daily milk yield and composition. Milk samples (∼5.0 million) were collected over a 5-yr period (2014–2019) within the milk recording system in Poland. Concentrations of mACE and mBHB determined by Fourier-transform infrared spectroscopy were used to categorize samples into 4 ketolactia groups. Based on threshold values of ≥0.15 mmol/L mACE and ≥0.10 mmol/L mBHB, ketolactia groups were normoketolactia (NKL; mACE <0.15 mmol/L and mBHB <0.10 mmol/L), BHB hyperketolactia (HYKLBHB; mACE <0.15 mmol/L and mBHB ≥0.10 mmol/L), ACE hyperketolactia (HYKLACE; mACE ≥0.15 mmol/L and mBHB <0.10 mmol/L), and ACE and BHB hyperketolactia (HYKLACEBHB; mACE ≥0.15 mmol/L and mBHB ≥0.10 mmol/L). To investigate ketolactia association with production outcomes, a linear model was developed, including ketolactia group, DIM, parity, their interactions, year-season as fixed effects, and random effects of herd and cow. Among all milk samples, 31.2% were classified as HYKL, and of these, 52.6%, 39.6%, and 7.8% were HYKLACEBHB, HYKLBHB, and HYKLACE, respectively. Ketolactia groups differed for all traits studied in all parities and DIM. Among HYKL groups, lowest milk yield was found in HYKLACEBHB cows, except for 6 to 30 DIM in first- and second-lactation cows. Milk yield of HYKLBHB cows was higher than that of NKL cows until 20 to 30 DIM, and then it was lower than NKL cows. Milk yield of HYKLACE cows was mostly lower than NKL cows. Energy-corrected milk (ECM) yield of HYKLACEBHB cows was higher than that of NKL cows until 30 to 35 DIM for second lactation and third lactation or greater, and in the whole study period for first lactation. The yield of ECM for HYKLBHB cows was mostly higher than that of NKL cows, whereas HYKLACE cows had higher ECM than NKL cows until 15 to 25 DIM and then was lower for the HYKLACE group. Milk composition differed among HYKL groups. Highest milk fat (MF) and lowest milk lactose (ML) contents were observed in HYKLACEBHB cows. Cows in HYKLACEBHB and HYKLBHB groups had higher MF and lower milk protein (MP; except in 6–8 DIM in first lactation) and ML content than NKL cows. Milk fat content was higher in HYKLACE than NKL cows in first lactation and during the first 30 to 40 DIM in older cows. Lactose content was lower in HYKLACE than in NKL cows within 30 to 40 DIM; afterward it was higher in NKL cows. Lower MP content was found in HYKLACE than in NKL cows, except during 6 to 9 DIM for cows in first lactation and third lactation or greater. In conclusion, HYKL is associated with altered milk production in all parities, but a range of these negative relations depends on ketone status addressing both ACE and BHB contents. Further research is needed to ascertain underpinning biochemical defects of HYKL from elevated ACE, alone or in combination with BHB, during early lactation.

  PublisherOA PDFDOI

• The impact of beef sire breed on dystocia, stillbirth, gestation length, health, and lactation performance of cows that carry beef × dairy calves

  Journal of Dairy Science · 2023-11-09 · 14 citations

  articleOpen accessSenior authorCorresponding

  In the United States, it is becoming common for dairy herds to mate a portion of cows to beef semen to create a value-added calf. The objectives of this study were to determine if dystocia risk, stillbirth (SB) risk, gestation length (GL), probability of early-lactation clinical disease events, early-lactation culling risk, or subsequent milk production differ between cows that carried calves sired by different beef breeds and those that carried Holstein-sired calves. Records from 10 herds contained 75,256 lactations from 39,249 cows that had calves with known Holstein or beef breed sires from the years 2010 to 2023. Calf sire breeds with ≥150 records included in analyses were Holstein, Angus, Simmental, Limousin, crossbred beef, and Charolais. Additional beef sire breeds that existed in lower frequency (n < 150 records) were condensed together and classified as "other." Because GL is a continuous variable, sire breed inclusion criteria were reduced to n ≥ 100 records; thus, Wagyu sires were included as their own breed group. Some records did not contain all variables of interest, thus models included fewer lactations depending on variable. Binomial generalized mixed models evaluated dystocia risk (defined as calving ease score ≥4 or calving ease score ≥3), SB risk, clinical health event risk (defined as lameness, mastitis, metabolic, reproductive, other, or any health events occurring within 60 d in milk [DIM]), and early culling risk (defined as death or culling within 60 DIM). Gestation length and test-date milk, fat, and protein yields were evaluated with mixed models. Calves sired by crossbred beef bulls had a greater probability of being stillborn (5%; 95% confidence interval lower = 2.9% upper = 9.0%) than those sired by Holstein bulls (2%; 95% confidence interval lower = 1.5%, upper = 2.7%). All beef-sired calves increased GL from that of Holstein-sired calves (277 ± 0.15 d) with Limousin (282 ± 0.81 d) and Wagyu-sired calves (285 d ± 0.79) resulting in the longest GL. The risk of dystocia, clinical health events, and early-lactation culling did not differ by calf sire breed nor did subsequent milk and component yield. Generally, carrying a calf sired by the beef breeds included in this study did not negatively affect the dairy cow.

  PublisherOA PDFDOI

• Genetic evaluation of health costs in US organic Holstein calves and cows

  JDS Communications · 2023-08-18 · 1 citations

  articleOpen accessSenior authorCorresponding

  Minimizing the incidence of disease on organic dairy farms is important for both economic and animal welfare purposes. The objective of this study was to estimate genetic parameters for total disease treatment costs using producer-recorded treatments in organic Holstein dairy calves and cows. Individual cow and calf health data were collected from 16 USDA certified organic farms from across the United States. Eleven of these farms provided treatment costs for some or all of the following cow health issues (mean cost): mastitis ($46.10), milk fever ($39.05), ketosis ($29.81), metritis ($28.66), retained placenta ($45.59), displaced abomasum ($439.71), lameness ($66.36), indigestion ($22.94), respiratory ($48.35), and died ($64.98). These farms also provided the following health costs for calves (mean cost): respiratory ($56.37) and scours ($25.21). Costs included consultant fees, therapeutics, and producer labor. The total lactational health cost (HCOST) was analyzed using animal models adjusted for the fixed effects of lactation and herd and the random effect of herd-year-season of calving with animal relationships based on the blending of pedigree and genomic relationships established from 2,347 genotyped cows. Along with HCOST, the binary traits stayability and presence of disease were included in a trivariate model such that lactations absent of disease were considered to be missing HCOST. To estimate the genetic relationship between nulliparous and primiparous health costs, a 2-trait linear model was fitted for total nulliparous health costs (NHCOST) and first lactation HCOST. The most expensive cow-lactation was $643.86 and 26.5% of lactations encountered disease. The heritability for HCOST was 0.03 ± 0.01, and the repeatability was 0.21 ± 0.01. The heritability of NHCOST was 0.06 ± 0.01, and the genetic correlation between NHCOST and HCOST was 0.98 ± 0.51. Traits representing the repeated nature of disease have a genetic component that should foster improved disease resistance among organic Holstein dairy cows. However, total cost of disease did not lead to gains in genetic variation over consideration of disease traits considered as binary variables and is a more laborious phenotype to obtain, diminishing its appeal for use in routine genetic evaluations.

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Frequent coauthors

• G.W. Rogers

  Arkansas Agricultural Experiment Station

  13 shared

• Wansheng Liu

  Pennsylvania State University

  13 shared

• Craig R. Baumrucker

  Pennsylvania State University

  12 shared

• Brad Heins

  University of Minnesota

  9 shared

• K.J. Harvatine

  Cornell University

  9 shared

• L.C. Hardie

  Iowa State University

  8 shared

• J. Clay

  Dairy Management

  8 shared

• G.A. Varga

  6 shared

Labs

• Dairy Cattle GeneticsPI

Education

• B.S.

  Cornell University

  1997

• Other

  The State University of New York at Morrisville

  1995

• M.S.

  The Pennsylvania State University

  2000

• Other

  The University of Wisconsin at Madison

  2001

• Ph.D.

  The University of Tennessee

  2003