Applied Animal Science最新文献

{"title":"Review: Vaccination against respiratory pathogens during the cow-calf phase: Effects on productive and health responses of feedlot cattle","authors":"Kelsey M. Harvey ,&nbsp;Reinaldo F. Cooke ,&nbsp;W. Isaac Jumper","doi":"10.15232/aas.2024-02592","DOIUrl":"10.15232/aas.2024-02592","url":null,"abstract":"<div><h3>Purpose</h3><div>Bovine respiratory disease (BRD) remains one of the costliest diseases affecting the beef industry, and vaccination is a key strategy to mitigate disease risk. This article discusses current knowledge of vaccine use and strategies during the cow-calf phase of beef production.</div></div><div><h3>Sources</h3><div>The primary source of information reviewed herein was independent, published, scientific peer-re- viewed literature.</div></div><div><h3>Synthesis</h3><div>Producers prioritize vaccination protocols as cattle progress through the segments of the beef pro- duction system, with BRD vaccine adoption rate increas- ing as cattle age. Vaccination against BRD pathogens dur- ing the cow-calf phase and before stressful events such as weaning, transportation, or feedlot entry enhances vaccine efficacy and health responses in feedlot cattle.</div></div><div><h3>Conclusions and Applications</h3><div>To maximize vac- cine effectiveness and ensure optimal protection from disease, the timing of vaccinations against BRD pathogens relative to disease challenge must be considered. Research is warranted to further explore the benefits of vaccination against BRD pathogens during the cow-calf phase on cattle health and performance during the feed- lot period.</div></div>","PeriodicalId":8519,"journal":{"name":"Applied Animal Science","volume":"41 4","pages":"Pages 273-283"},"PeriodicalIF":1.4,"publicationDate":"2025-07-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144687495","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effects of stocking rate on perinatal cows and subsequent growth and performance of calves from birth to carcass: A long-term epigenetic analysis","authors":"Douglas R. Tolleson ,&nbsp;Dan Quadros ,&nbsp;Charles R. Long ,&nbsp;Kelli D. Norman ,&nbsp;Monte Rouquette Jr.","doi":"10.15232/aas.2024-02605","DOIUrl":"10.15232/aas.2024-02605","url":null,"abstract":"<div><h3>Objective</h3><div>Our objective was to analyze long-term cow-calf records to document effects of perinatal stocking rates on subsequent cow and calf performance from birth to slaughter.</div></div><div><h3>Materials and Methods</h3><div>Over 1,900 cattle records from F-1 (Hereford or Angus × Brahman) cows calving in the fall or winter and stocked on bermudagrass at 3 distinct stocking rates (i.e., low [LO; 2.4 cow-calf pairs {CC} per hectare], moderate [MOD; 3.8 CC per hectare], or high [HI; 5.8 CC per hectare]) were analyzed. At termination of the stocker period, calves were shipped to a commercial feedlot. When most of the cattle in a pen reached a visual backfat of 1.25 cm, they were weighed and shipped 50 km to an abattoir for slaughtering and carcass grading. Carcass traits included hot carcass weight, DP, backfat, marbling score, predicted YG, longissimus muscle area, and KPH percentage.</div></div><div><h3>Results and Discussion</h3><div>Calving season, cow age, calf sex, gestation stocking rate (for a given CC and for the cow’s previous calf), and lactation stocking rate had various effects on cow, suckling calf, feedlot yearling, and carcass measures. High stocking rate generally decreased calf performance, yearling feedlot performance, and carcass parameters.</div></div><div><h3>Implications and Applications</h3><div>Stocking rate during gestation had substantial implications for cow, fetus, and calf nutrition and, thus, subsequent offspring performance from birth to slaughter. Stocking rate, particularly during the calf rearing period, was a critical component of grazing management within the context of weather, site production potential, and operational strategy.</div></div>","PeriodicalId":8519,"journal":{"name":"Applied Animal Science","volume":"41 4","pages":"Pages 377-398"},"PeriodicalIF":1.4,"publicationDate":"2025-07-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144687536","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"In vitro and in situ estimation of ruminal and intestinal digestion of lobster and crab shell meal","authors":"T.C. Stahl ,&nbsp;L.J. Valentine ,&nbsp;A. Abend ,&nbsp;T. Islam ,&nbsp;P.S. Erickson","doi":"10.15232/aas.2024-02632","DOIUrl":"10.15232/aas.2024-02632","url":null,"abstract":"<div><h3>Objective</h3><div>This experiment compared in vitro dry matter digestibility (IVDMD), in vitro intestinal protein degradability, and in situ degradability of lobster shell meal (LM), crab shell meal (CM), soybean meal (SBM), and blood meal (BM), and chitin degradability of LM and CM.</div></div><div><h3>Materials and methods</h3><div>The 48-h IVDMD was determined in rumen fluid. For in situ DM and CP degradability, 4 Holstein cows were used to test the degradation rates of SBM, BM, LM, and CM. Samples were removed after 2, 4, 8, 12, 24, and 48 h. Protein fractions and degradation rates were determined. Fraction A was the washout before rumen suspension. Fraction C was the material remaining after 48 h. Fraction B was the initial sample − (A + C). The CP degradation rate was calculated by converting fraction B to the natural log and calculating the slope. The effective CP degradability was calculated by multiplying the sum of fractions A and B by the CP degradation rate and dividing that by the sum of the CP degradation rate and the outflow rate (2%, 5%, or 8%). For intestinal digestibility, Dacron bags (Ankom R510, pore size 50 μm, Ankom Technology) were removed from the rumen at 12 h, incubated with HCl and pepsin for 1 h, and then incubated for 12 h with protease and buffer to mimic intestinal digestion. After removal, sample bags were dried for 48 h at 55°C.</div></div><div><h3>Results and Discussion</h3><div>Soybean meal was more soluble than other feeds, and BM tended to be less soluble than LM or CM. Similarly, 12-h DM degradability was greater for SBM than for BM, LM, and CM; and BM was less than LM and CM. Intestinal DM digestibility was similar among feeds. Blood meal intestinal digestibility was estimated to be more than that of LM or CM. Rumendegradable protein was greater for SBM than for the other feeds. Blood meal was more degradable than LM and CM. Protein fraction A was similar for LM and CM, whereas fraction B and fractions A + B tended to be greater for CM than LM and fraction C tended to be greater for LM than CM. Soybean meal had greater fraction B and the sum of fractions A and B than the other feeds, and lesser fraction C. Degradation rates were greater for SBM than they were for the other feeds. Soluble chitin was greater for CM than LM, but degradability rates at 12 h and 48 h were similar.</div></div><div><h3>Implications and applications</h3><div>Results indicate that crustacean shell wastes may be used in cattle diets. More research should be conducted on feeding them to cattle.</div></div>","PeriodicalId":8519,"journal":{"name":"Applied Animal Science","volume":"41 3","pages":"Pages 148-155"},"PeriodicalIF":1.4,"publicationDate":"2025-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144263197","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Random metaphylactic effects of tulathromycin on health outcomes, complete blood count, antimicrobial use, growth performance, and Salmonella enterica shedding in high-risk beef steers","authors":"C.W. Dornbach ,&nbsp;P.R. Broadway ,&nbsp;N.C. Burdick Sanchez ,&nbsp;M.S. Grant ,&nbsp;K.D. Childress ,&nbsp;B.J. Sitka ,&nbsp;T.A. Loeffler ,&nbsp;L.G. Canterbury ,&nbsp;M.L. Galyean ,&nbsp;K.E. Hales","doi":"10.15232/aas.2025-02679","DOIUrl":"10.15232/aas.2025-02679","url":null,"abstract":"<div><h3>Objective</h3><div>We evaluated the effects of random metaphylaxis administered with tulathromycin at feedlot arrival to 0%, 33%, 66%, and 100% of high-risk beef steers on health outcomes, growth performance, complete blood cell count, <em>Salmonella</em> shedding, and antimicrobial use during a 35-d receiving period.</div></div><div><h3>Materials and Methods</h3><div>Crossbred beef steers (n = 232; arrival BW = 213 ± 6.3 kg) were used in a generalized complete block design consisting of 2 source blocks, each with 4 BW blocks and 4 treatments. Steers were randomly assigned to pen within source block, and experimental treatments were (1) negative control, s.c. injection with sterile saline (0M); (2) tulathromycin administered at random to 33% of steers within a pen (33M); (3) tulathromycin administered at random to 66% of steers within a pen (66M); or (4) conventional metaphylaxis with tulathromycin administered to 100% of steers within a pen (100M). Body weight, whole blood, and fecal samples were collected on d 0, 14, and 35. Metaphylactic treatment was included in the model as a fixed effect, and BW block within source block was included as a random effect.</div></div><div><h3>Results and Discussion</h3><div>Initial bovine respiratory disease treatments were 108% and 62.2% greater for 0M and 33M, respectively, compared with the average treatment prevalence for 66M and 100M steers. No differences were detected between treatments for BW, ADG, DMI, or G:F from d 0 to 35 with dead cattle excluded or included. Hematology metrics were mostly affected by day, though reticulocyte count and eosinophil percentage differed among treatments. Fecal <em>Salmonella</em> concentration and prevalence did not differ among treatments but increased from d 0 to 14 before equalizing through d 35.</div></div><div><h3>Conclusions and Applications</h3><div>These data suggest that metaphylaxis can be administered to 66% of cattle without increasing bovine respiratory disease morbidity or decreasing growth performance. Moreover, random metaphylaxis to 66% of steers at arrival decreased the amount of active drug compound administered compared with 0M and the number of antimicrobial injections administered in each pen compared with 100M. <em>Salmonella</em> shedding was not affected by random metaphylaxis with tulathromycin in high-risk beef steers.</div></div>","PeriodicalId":8519,"journal":{"name":"Applied Animal Science","volume":"41 3","pages":"Pages 176-189"},"PeriodicalIF":1.4,"publicationDate":"2025-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144263757","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Interactions of change in nutrition before and after artificial insemination on plasma and uterine histotroph mineral concentrations in beef heifers","authors":"T.N. Andrews ,&nbsp;K.M. Epperson ,&nbsp;J.J.J. Rich ,&nbsp;S. Menegatti Zoca ,&nbsp;A.C. Kline ,&nbsp;L.K. Quail ,&nbsp;S.R. McCoski ,&nbsp;C. Sanford ,&nbsp;A.L. Zezeski ,&nbsp;T.W. Geary ,&nbsp;J.A. Walker ,&nbsp;G.A. Perry","doi":"10.15232/aas.2024-02634","DOIUrl":"10.15232/aas.2024-02634","url":null,"abstract":"<div><h3>Objective</h3><div>These studies evaluated embryo recovery and nutritional changes before and after artificial insemination (AI) on circulating and uterine histotroph mineral concentrations.</div></div><div><h3>Materials and Methods</h3><div>In study 1, heifers (n = 79) were assigned to 1 of 2 treatments before and after AI: (1) low, 90% and 81% of maintenance energy requirements, or (2) high, 162% and 148% of maintenance energy requirements. At AI (d 0) half of the heifers were reassigned to the other treatment. Uteri were flushed on d 7 or 8. In study 2, heifers (n = 50) were only treated after AI (77.5% or 161.5% of maintenance energy requirements) until uteri were flushed on d 14.</div></div><div><h3>Results and Discussion</h3><div>In study 1, the low diet after AI resulted in reduced uterine S and Ca, indicating nutrient restriction after AI altered the uterine histotroph. When an embryo was recovered, uterine S, Ca, K, and Al were reduced, and Mg tended to be reduced. Thus, the embryo is likely using these minerals for growth and development. Plasma Mn, Mo, Zn, and Se were affected by time, indicating mineral bioavailability may vary during the estrous cycle. In study 2, heifers on the low diet tended to have elevated plasma Co and reduced uterine Fe. When an embryo was recovered, uterine Mg and S were reduced, and uterine Ca tended to be reduced and Mn tended to be elevated. Thus, Mg and S may be used by the developing embryo.</div></div><div><h3>Implications and Applications</h3><div>In summary, energy restrictions after AI reduced mineral concentrations in the uterine histotroph, potentially hindering embryo development as embryos appeared to use S, Ca, and Mg for development.</div></div>","PeriodicalId":8519,"journal":{"name":"Applied Animal Science","volume":"41 3","pages":"Pages 215-229"},"PeriodicalIF":1.4,"publicationDate":"2025-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144263800","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effects of low temperature and ensiling time on fermentation and nutritive value of sorghum- sudangrass silage","authors":"Elizabeth Coons ,&nbsp;Matthew S. Akins","doi":"10.15232/aas.2024-02636","DOIUrl":"10.15232/aas.2024-02636","url":null,"abstract":"<div><h3>Objective</h3><div>The study evaluated the fermentation and nutritive value of freeze-affected sorghum-sudangrass si- lage stored at 2 temperatures.</div></div><div><h3>Materials and Methods</h3><div>Sorghum-sudangrass for- age affected by several frost/freeze events and lodging was harvested and chopped, then ensiled in vacuum-sealed plastic mini-silos. Silos were stored at either 4°C or 20°C for 5, 10, 15, 30, or 60 d with triplicate silos at each time. Resulting silage was evaluated for pH, silage acids and al- cohols, nitrates, and nutritive value. Aerobic stability was also measured on silages stored for 60 d.</div></div><div><h3>Results and Discussion</h3><div>Silage pH decreased more quickly at 20°C, with silage at 4°C having a 10-d lag be- fore pH decreased. Lactic, acetic, and propionic acid con- centrations were greater at all times for silage stored at 20°C. Ethanol and methanol were greater in silage stored at 20°C, which is speculated to be from increased yeast activity. The decreased fermentation for silage stored at 4°C resulted in 1% greater DM recovery; however, aerobic stability was better for silage stored at 20°C (149 h) than 4°C (47 h) likely due to greater acetic acid concentration. Silage storage at 4°C resulted in lower NDF concentration due to less silage acid production, with no other changes in nutritive value observed due to storage temperature. Nitrate concentrations were low in the initial forage (76 mg/kg DM) with concentrations lower after storage (43– 50 mg/kg DM), as expected.</div></div><div><h3>Implications and Applications</h3><div>Storage temperature of sorghum-sudangrass silage had a significant impact on silage acid production and aerobic stability with limited fermentation the first 10 to 15 d of storage. This research is applicable when harvesting forage during cold or freez- ing temperatures, which limits early fermentation. Allow- ing standing forage to thaw/warm before harvest may improve fermentation and aerobic stability. Additional research on changes in nitrates of frosted sorghum forage is needed to confirm results in forage with high initial nitrate levels.</div></div>","PeriodicalId":8519,"journal":{"name":"Applied Animal Science","volume":"41 3","pages":"Pages 156-161"},"PeriodicalIF":1.4,"publicationDate":"2025-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144263198","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effects of supplementing Bacillus subtilis PB6 on health outcomes, Salmonella spp. prevalence, growth performance, and carcass characteristics in finishing beef cattle","authors":"A.N. Hanratty ,&nbsp;K.E. Hales ,&nbsp;C.W. Dornbach ,&nbsp;N.C. Burdick-Sanchez ,&nbsp;A.B. Word ,&nbsp;B.P. Holland ,&nbsp;C.L. Maxwell ,&nbsp;J.E. Hergenreder ,&nbsp;L.G. Canterbury ,&nbsp;J.T. Leonhard ,&nbsp;J. Vasconcelos ,&nbsp;D. LaFleur ,&nbsp;S. Trojan ,&nbsp;M.L. Galyean ,&nbsp;P.R. Broadway","doi":"10.15232/aas.2024-02671","DOIUrl":"10.15232/aas.2024-02671","url":null,"abstract":"<div><h3>Objective</h3><div>We evaluated the effects of supplementation with <em>Bacillus subtilis</em> PB6 on health outcomes, growth performance, fecal <em>Salmonella</em> prevalence, and carcass characteristics in finishing beef steers supplemented the first 60 d or the entire 224 d of the feeding period with <em>B. subtilis</em> PB6.</div></div><div><h3>Materials and Methods</h3><div>Crossbred beef steers (n = 3,150; arrival BW 274 ± 30.6 kg) were used in a randomized complete block design consisting of 3 dietary treatments (n = 15 blocks per treatment). Treatments included the following: (1) a control diet contained no <em>B. subtilis</em> PB6 (CON); (2) a diet that included CLOSTAT supplemented with 0.5 g/steer daily of <em>B. subtilis</em> PB6 (CLOSTAT 500, Kemin Industries Inc.) to provide 6.6 × 10⁹ cfu/g active ingredient for the entire duration of the feeding period (CLO); or (3) a diet that included <em>B. subtilis</em> PB6 at a dose of 0.5 g/steer daily the initial 60 d of the feeding period (CLO60). Based on established criteria, metaphylaxis was administered after arrival to 7 blocks (21 pens) to prevent bovine respiratory disease. Fresh fecal matter was collected aseptically from multiple locations (n = 10 locations within each pen), and lymph nodes were obtained at slaughter from a subset of carcasses within each lot (n = 12) to determine <em>Salmonella</em> prevalence.</div></div><div><h3>Results and Discussion</h3><div>No interactions were observed between treatment and metaphylaxis throughout the study. The percentage of respiratory deaths was greater for steers in CLO60 than CLO and CON from d 0 to 60, but there were no growth performance differences noted among treatments. Likewise, there were no differences in lymph node prevalence of <em>Salmonella</em> among treatments; however, there was a decrease in fecal <em>Salmonella</em> prevalence for CON versus CLO and CLO60 steers from d 45 to 90.</div></div><div><h3>Implications and Applications</h3><div>Supplementation of <em>B. subtilis</em> PB6 for the first 60 d or the entire feeding period had no effect on health outcomes, growth performance, and carcass characteristics. Moreover, feeding <em>B. subtilis</em> PB6 for the first 60 d or entire feeding period did not affect <em>Salmonella</em> prevalence in the subiliac lymph nodes.</div></div>","PeriodicalId":8519,"journal":{"name":"Applied Animal Science","volume":"41 3","pages":"Pages 205-214"},"PeriodicalIF":1.4,"publicationDate":"2025-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144263767","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Notice of RETRACTION: “Perspectives and Commentary: Fat nutrition and metabolism of early- lactation dairy cows” (Appl. Anim. Sci. 40:729–737)","authors":"A.F. Kertz","doi":"10.15232/aas.2025-41-3-0147","DOIUrl":"10.15232/aas.2025-41-3-0147","url":null,"abstract":"","PeriodicalId":8519,"journal":{"name":"Applied Animal Science","volume":"41 3","pages":"Page 147"},"PeriodicalIF":1.4,"publicationDate":"2025-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144263270","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Invited Review: The weaning transition in dairy calves—Why so traumatic?*","authors":"J.K. Drackley","doi":"10.15232/aas.2024-02657","DOIUrl":"10.15232/aas.2024-02657","url":null,"abstract":"<div><h3>Purpose</h3><div>The purpose of this review article was to identify physiological and management factors that affect the weaning transition in dairy calves, which can be a dif- ficult time for calves.</div></div><div><h3>Sources</h3><div>Peer-reviewed journal articles were used to compile the review.</div></div><div><h3>Synthesis</h3><div>Weaning is often a period of stress and lost performance for calves, in many cases resulting in respira- tory disease or diarrhea caused by coccidiosis or acidosis. Physiological factors contribute to the difficulty, including the expanding gut fill, allometric growth of the reticuloru- men and gastrointestinal tract, and development of the ruminal epithelium. Stabilizing ruminal pH above 6.0 so that fiber fermentation can proceed is a major challenge for calves. Management practices should aim to maximize starter intake while avoiding ruminal acidosis. Providing a high-quality calf starter is extremely important, including appropriate ingredient and chemical composition as well as physical form. Calves should not be weaned until they are consuming an adequate amount of starter to allow the discontinuation of milk intake and should be weaned gradually rather than abruptly. Although small amounts of forage before and after weaning may be useful in calves fed pelleted or ground starters and not bedded on straw, calves should not have free access to alfalfa hay. Water ac- cess is critical because the rumen needs water to support the developing microbial ecosystem. Stressful management tasks such as dehorning or vaccination should not be per- formed at the same time as weaning. Ruminal acidosis is likely more common than has been recognized and causes decreased intake, decreased growth, and diarrhea, espe- cially in calves soon after weaning.</div></div><div><h3>Conclusions and Applications</h3><div>The weaning tran- sition is a period of stress for calves. Managing starter quality, time and rate of weaning, forage and water avail- ability, concurrent stressors, and acidosis can help avoid difficult weaning and improve the welfare of young calves without losing performance.</div></div>","PeriodicalId":8519,"journal":{"name":"Applied Animal Science","volume":"41 3","pages":"Pages 190-204"},"PeriodicalIF":1.4,"publicationDate":"2025-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144263766","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Invited Review: Connecting the dots—Calving difficulty, age at first calving, and enhanced cow production*","authors":"M.I. Marcondes ,&nbsp;J.C.C. Chagas ,&nbsp;A.F. Kertz ,&nbsp;T. Allen ,&nbsp;J.M. Bewley","doi":"10.15232/aas.2024-02620","DOIUrl":"10.15232/aas.2024-02620","url":null,"abstract":"<div><h3>Purpose</h3><div>We aimed to explore the relationships among calving difficulty (CD), production traits, age at first calving (AFC), and culling in dairy cattle.</div></div><div><h3>Sources</h3><div>Data from 687 US dairy farms, encompassing 1,048,574 CD observations scored from 1 to 5, were analyzed. Scores of CD 5 were adjusted to 4 due to limited interactions with other variables. The focus was on Holstein, Jersey, and dairy cross breeds, and parity was categorized as primiparous or multiparous.</div></div><div><h3>Synthesis</h3><div>The study comprised 4 steps. Step 1 assessed the effect of CD on milk yield, fat, protein, ECM, and peak milk production with fixed effects of CD, parity, calf sex (CS), and breed and random effects of calving year, calving season, and herd. Step 2 analyzed AFC, using linear and quadratic covariates, on the same parameters. Step 3 examined CD as the response variable in the step 2 database. Step 4 used logistic regression to assess risk factors associated with CD and culling reasons. Our results showed the following. Step 1: CD significantly affected milk yield, ECM, fat, protein, and peak milk production, with declines in production traits for CD &gt;2, the least values at CD 4. Step 2: Significant linear and quadratic AFC covariates showed optimal milk performance at 27 to 28 mo. Step 3: CD was influenced by breed, CS, AFC, and interactions, with minimal CD observed at AFC of 23 to 26 mo. Step 4: Greater CD was linked to culling for nondairy purposes.</div></div><div><h3>Conclusions and Applications</h3><div>Calving difficulty affects production traits and is influenced by parity, breed, and CS, but its effect is less significant than expected. The AFC, particularly over 26 mo, has a more pronounced effect on CD. Greater CD levels are associated with increased involuntary culling.</div></div>","PeriodicalId":8519,"journal":{"name":"Applied Animal Science","volume":"41 3","pages":"Pages 237-251"},"PeriodicalIF":1.4,"publicationDate":"2025-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144263360","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}