Journal of Dairy Science最新文献

{"title":"Assessment of conformation scoring of the limbs as a potential explanatory factor for claw health in dairy cows.","authors":"M N E Hillen, B Vidondo, C Syring, M Welham Ruiters, J Weber, L Mazurek, A Steiner, J Becker","doi":"10.3168/jds.2025-26520","DOIUrl":"https://doi.org/10.3168/jds.2025-26520","url":null,"abstract":"<p><p>The selection of breeding animals is critical for a robust livestock population. Conformation trait scoring represents a practical approach to evaluate a cow's potential for productivity, longevity, and suitability for breeding. The scored traits are assigned to 4 subsections: frame and capacity, pelvis, limbs and udder. Previous studies examining associations between specific limb conformation traits and the incidence of claw lesions have found low to moderate associations. This observational study (n = 21,145 cows) investigates associations between claw health and the score encompassing all traits of the 'limbs' subsection and the final score per cow encompassing all subsections. This approach aims to capture potential associations between limb conformation and claw health that may not be linked to a single trait, but the overall limb conformation. Claw health data were recorded by professional claw trimmers participating in the Swiss Claw Health Project. The claw health data were aggregated to 3 outcome values. For each recording, disorder occurrence and severity were combined to a value representing claw health in general encompassing all claw lesions. Also, 2 sub values were created, one encompassing the stages of digital dermatitis only, the other one claw horn lesions only. The score for the 'limbs' subsection showed statistically significant associations with the occurrence of claw lesions in general and mechanical-metabolic lesions. The effect sizes, however, are small ranging 10 to 59% increased odds across score categories for the occurrence of lesions of the digit in general and 10-104% for the occurrence of claw horn lesions. For cows with the lowest rating in the 'limbs' trait subsection, the odds for higher lesion severity increases by 66%. To contextualize and compare these effect sizes, 'parity' and 'breed' were included based on previous studies. 'Herd size' and 'claw trimming frequency' were incorporated to represent management context. In higher parities, claw lesions in general and mechanical-metabolic lesions showed increased prevalences but prevalences of digital dermatitis decreased. Holstein-Friesian cows exhibited higher prevalences of most claw lesions compared with Brown Swiss, the difference being particularly pronounced for digital dermatitis. Larger herd size is associated with higher odds for claw disorders in general and digital dermatitis, and increased claw trimming frequency is associated with higher odds for digital dermatitis. The study concludes that limb conformation scoring can be a supportive tool in assessing a cow's potential for future claw health. To justify its use in breeding selection, further research on trait heritability is needed. The small effect sizes reflect the multifactorial nature of claw health.</p>","PeriodicalId":354,"journal":{"name":"Journal of Dairy Science","volume":" ","pages":""},"PeriodicalIF":3.7,"publicationDate":"2025-06-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144293028","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Dry period heat tolerance affects placental efficiency, apoptosis, and protein expression in Holstein cows.","authors":"X Chen, C Li, T Fang, J Yao, X Gu","doi":"10.3168/jds.2025-26422","DOIUrl":"https://doi.org/10.3168/jds.2025-26422","url":null,"abstract":"<p><p>The placenta plays a key role in fetal growth and functions to transport nutrients that are vital to the fetus. Heat stress (HS) impairs placental function in cows, affecting fetal development. There is limited information on the effects of HS on the placenta of heat-tolerant and -sensitive dry cows. The objective of this study was to assess differences in placental efficiency, morphology, apoptosis, and placental proteomics in heat-tolerant and -sensitive dry cows, and to investigate the underlying mechanisms of the effect. Sixty-six dry cows were measured for respiratory rate, body surface temperature, and microenvironmental temperature-humidity index, by 56.94 ± 16.04 bpm, 36.11 ± 0.38°C, and 80.65 ± 3.31 accordingly, indicating that the cows were exposed to HS. A mixed-effects model was applied to analyze the measured indicators, and clustering was used to classify them as heat-tolerant dry cows (n = 19) and heat-sensitive dry cows (n = 47). Placentals were collected from heat-tolerant (n = 8) and -sensitive (n = 13) dry cows. The placental weight, number of placental cotyledons, and fetal birth weight were recorded. Placental efficiency (calf birth weight: placental weight ratio), morphology, apoptosis, and proteomic differences were assessed in heat-tolerant and -sensitive dry cows. Five placental cotyledon samples from each group underwent hematoxylin and eosin staining, terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay, and label-free proteomic analysis to assess microstructure, apoptosis, and differential protein expression, respectively. Results indicate that placental efficiency was significantly higher in heat-tolerant dry cows compared with heat-sensitive dry cows. Heat-tolerant cows exhibited a significantly lower apoptosis index (TUNEL+ cells: the total number of cells ratio) compared with heat-sensitive cows. A total of 3,691 proteins were identified, with 160 showing differential expression. The endocytosis pathway was significantly enriched in both Gene Ontology analysis and Kyoto Encyclopedia of Genes and Genomes pathway enrichment. Heat tolerance of heat-stressed dry cows improves placental efficiency, exhibits lower placental apoptosis, and maintains nutrient transport of placenta through the endocytosis pathway, which are likely due to the coordinated action of multiple pathways, contributing to better overall placental function in heat-tolerant cows.</p>","PeriodicalId":354,"journal":{"name":"Journal of Dairy Science","volume":" ","pages":""},"PeriodicalIF":3.7,"publicationDate":"2025-06-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144293097","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Milking frequency and dairy cow susceptibility to lipolysis interact to alter milk lipolysis and composition.","authors":"C Hurtaud, L Bernard, A Rau, C Cebo","doi":"10.3168/jds.2025-26537","DOIUrl":"https://doi.org/10.3168/jds.2025-26537","url":null,"abstract":"<p><p>Lipolysis is an ongoing issue for the French dairy industry that must be minimized. Milk lipolysis is defined as the hydrolysis of triglycerides, the major component of milk fat, resulting in the release of short-chain fatty acids responsible for rancid flavor and partial glycerides that impair functional properties such as foaming and creaming abilities. Milk lipolysis is a complex phenomenon that depends on both animal parameters and farming factors. Milk spontaneous lipolysis is higher in milk from automatic milking systems, which could be due to the number and intervals of milking, as lipolysis is lower in the case of a single daily milking. In addition, considerable interindividual variability in milk lipolysis has been observed, with some dairy cows being highly susceptible or nonsusceptible to lipolysis. The objective of this study was therefore to evaluate the impact on spontaneous milk lipolysis of different milking frequencies (i.e., 1 [morning or evening], 2, or 3 milkings per day) with evenly spaced milking intervals while accounting for individual susceptibility to lipolysis. To achieve this goal, 32 primiparous and multiparous dairy cows in mid-lactation were conducted using a continuous design with milking frequency as the main factor for a period of 3 wk. Four treatments were applied on 4 groups of cows: 1 milking per day at 6:00 a.m. (1M6am), 1 milking per day at 6:00 p.m. (1M6pm), 2 milkings per day at 6:00 a.m. and 6:00 p.m. (2M), and 3 milkings per day at 6:00 a.m., 2:00 p.m., and 10:00 p.m. (3M). In each group, there were 4 susceptible (SUS) dairy cows (lipolysis of SUS >0.70 mEq/100 g fat) and 4 nonsusceptible (NONSUS) dairy cows (lipolysis of NONSUS <0.70 mEq/100 g fat). As expected, 2M and 3M milkings increased milk yield by up to 30% compared with once-a-day milking. We confirmed that milk spontaneous lipolysis was influenced by increased milking frequency: compared with 2M, we observed more lipolysis with 3M and less with 1M. Regardless of the lipolysis susceptibility, the 1M6am and 1M6pm treatments caused a similar reduction in lipolysis. On the other hand, lipolysis was significantly higher in SUS cows with 2M and 3M treatments. In conclusion, although increased milking frequency results in greater milk yield, our results indicate that it can adversely impact milk quality with regard to free fatty acid concentrations. Conversely, although once-a-day morning or evening milking lead to decreased milk yield, they significantly reduced milk lipolysis regardless of a cow's susceptibility to lipolysis.</p>","PeriodicalId":354,"journal":{"name":"Journal of Dairy Science","volume":" ","pages":""},"PeriodicalIF":3.7,"publicationDate":"2025-06-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144293108","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effects of Rhodobacter sphaeroides protein on growth performance, nutrient digestibility, rumen fermentation, and serum metabolites in dairy calves during the pre- and postweaning periods.","authors":"Mahmoud M Abdelsattar, Minchao Su, Lingyun Kang, Dong Chen, Naifeng Zhang, Yan Tu, Qiyu Diao, Wenzhang Zhou, Yanliang Bi, Yu Hou","doi":"10.3168/jds.2024-26158","DOIUrl":"https://doi.org/10.3168/jds.2024-26158","url":null,"abstract":"<p><p>This study used Rhodobacter sphaeroides protein (RSP) as an innovative dietary protein source for Holstein dairy calves. We investigated its effects on growth performance, nutrient digestibility, rumen fermentation, and serum metabolites, antioxidants, immunoglobulins, and inflammatory factors. A total of 45 female Holstein calves (36.54 ± 1.68 kg of BW; 1 d of age) were randomly assigned to 3 treatment groups and fed either a control diet (CON) or diets with 5.89% or 11.49% RSP (RS1 and RS2, respectively) on a diet DM basis for 14 wk. The inclusion of RSP linearly increased BW and ADG, whereas it quadratically decreased DMI. There was a quadratic effect for gain-to-feed ratio and hip height, with higher mean values for the RS1 group. In addition, the dietary RSP tended to result in a linear increase in the overall withers height and postweaning heart girth. The dietary RSP reduced linearly the digestibility of DM and OM and tended to reduce linearly the digestibility of NDF and ADF. The levels of rumen butyrate showed a linear decrease in RSP calves. There was a quadratic effect for serum aspartate aminotransferase, with the highest value being for RS2 group. Increasing dietary RSP quadratically affected serum triglyceride levels, with the highest value being for the RS1 group. Meanwhile, serum alanine aminotransferase levels were quadratically decreased by RSP, with the RS1 group having the lowest levels. A quadratic trend effect was observed for serum albumin and total protein, with the highest values being in the RS1 group. The levels of lactate dehydrogenase, BUN, malondialdehyde, IL-10, and immunoglobulins decreased linearly with RSP. In contrast, total antioxidant capacity and the levels of superoxide dismutase, catalase, tumor necrosis factor-α, IL-8, and IL-6 increased linearly. In addition, the serum levels of low- and high-density lipoprotein, cholesterol, IL-4, IL-22, and glutathione peroxidase tended to increase linearly with the inclusion of dietary RSP. In conclusion, dietary inclusion of RSP in dairy calves reduced DMI, nutrient digestibility, and serum immunoglobulins levels, particularly at higher inclusion rates, whereas it improved ADG and antioxidant capacity.</p>","PeriodicalId":354,"journal":{"name":"Journal of Dairy Science","volume":" ","pages":""},"PeriodicalIF":3.7,"publicationDate":"2025-06-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144273875","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effects of supplemental levels of zinc, copper, and manganese on apparent absorption and tissue retention in growing bulls.","authors":"J-B Daniel, J Martín-Tereso","doi":"10.3168/jds.2025-26774","DOIUrl":"https://doi.org/10.3168/jds.2025-26774","url":null,"abstract":"&lt;p&gt;&lt;p&gt;Apparent trace metal absorption and tissue retention upon incremental levels of supplemental Zn, Cu, and Mn were studied in growing cattle. A total of 60 Holstein bulls (age = 246 ± 5 d, BW = 329 ± 26 kg) were enrolled for the study and fed for 6 to 9 wk a diet consisting of barley straw (15%), molasses (10%), and a pelleted concentrate (75%; 78, 15, and 91 mg/kg DM for Zn, Cu, and Mn, respectively). Thereafter, 20 bulls were randomly selected and slaughtered for determination of a baseline tissue trace metal composition. The remaining 40 bulls (age = 293 ± 9 d, BW = 385 ± 21 kg) were then blocked based on BW in 8 blocks of 5 bulls. Bulls within a block were randomly assigned to 1 of 5 diets defined by increasing supplemental levels of Zn, Cu, and Mn (all in the sulfate salt form), with the following total dietary contents, respectively: with no supplementation of Zn, Cu, Mn (BASAL; 38, 7, and 47 mg/kg DM), with supplementation of 20 mg Zn/kg DM, 5 mg Cu/kg DM, and 20 mg Mn/kg DM (SUP 1; 61, 11, and 68 mg/kg DM), with supplementation of 40 mg Zn/kg DM, 10 mg Cu/kg DM, and 40 mg Mn/kg DM (SUP 2; 78, 15, and 91 mg/kg DM), with supplementation of 80 mg Zn/kg DM, 20 mg Cu/kg DM, and 80 mg Mn/kg DM (SUP 3; 123, 26, and 136 mg/kg DM), or with supplementation of 160 mg Zn/kg DM, 40 mg Cu/kg DM, and 160 mg Mn/kg DM (SUP 4; 195, 43, and 214 mg/kg DM). These diets were fed for 12 wk, and a complete collection of feces and urine was performed on wk 4, 8, and 12 to determine trace metal balance (intake - feces - urine) and apparent absorption. After this feeding period, all bulls were slaughtered and gastrointestinal tissues, whole organs (heart, liver, spleen, and kidney), bile, cervical vertebra, and tibia were collected at the slaughterhouse. All samples were dried, ground, and analyzed for trace metals. Linear and quadratic effects of dietary trace metal supplementation were evaluated using a model that included block as a fixed effect and week as a repeated measure when applicable. Increasing supplemental levels of Zn, Mn, and Cu resulted in linear increases in fecal output of all 3 metals, with 90%, 89%, and 98% of the additional Zn, Mn, and Cu fed being lost in feces. Apparent Mn and Cu absorption efficiency decreased quadratically with increasing supplementation rate, whereas apparent Zn absorption efficiency was not significantly affected, resulting in a linear increase in Zn balance. Despite a decreasing absorption efficiency, Mn balance also linearly increased with supplementation rate, whereas Cu balance was not significantly affected. Hepatic Cu increased with higher Cu intakes, but the marginal rate of increase diminished as Cu intake increased. For all gut tissues, Mn concentration increased linearly with Mn intake. Remarkably, urinary Zn, Mn, and Cu excretions were all linearly increased with greater dietary intakes. Although the total amounts of urinary excretions were low (&lt;0.3% of intake), these results suggest increasing metabolic a","PeriodicalId":354,"journal":{"name":"Journal of Dairy Science","volume":" ","pages":""},"PeriodicalIF":3.7,"publicationDate":"2025-06-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144273876","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effects of wilting extent on the concentration of phytoestrogens, nutritional value, microbial populations, and in vitro ruminal methane emissions of red clover hay and silage across stages.","authors":"D Zamudio, R A De Castro, A P Jimenez-Lagos, M V S B Cardoso, M A Killerby, G Pereira, M R M Lima, C Knight, J J Romero","doi":"10.3168/jds.2025-26321","DOIUrl":"https://doi.org/10.3168/jds.2025-26321","url":null,"abstract":"<p><p>We evaluated the effects of insufficient (WET) or extended (CUR) wilting on the concentration of phytoestrogens, nutritional value, microbial populations, in vitro ruminal methane emissions, and in situ degradability of red clover silage (DM: 294 and 453 g/kg) and hay (DM: 651 and 891 g/kg, respectively) across storage stages. Measurements were taken at the start of storage (STRT), after 14 d (early stage of storage), and once storage processes had stabilized for hay and silage (50 and 78 d, respectively; late stage). Only l samples of hay and silage were tested for the in situ procedure. Data were analyzed as a randomized complete block design (5 blocks) with a 2 (wilting extents) × 2 (conservation methods) × 3 (storage stages) factorial. Results showed that storage DM losses were greater for WET versus CUR hay, but no differences were observed within silage. Extended wilting of hay and silage preserved better sugars during storage relative to insufficient wilting. Due to microbial spoilage, the NH₃-N of WET hay was greater than CUR hay after 14 d of storage, but the opposite was observed after 50 d. The NDF of WET hay increased across storage stages, whereas it remained stable for CUR hay. In contrast, the NDF levels of both WET and CUR silage decreased during the ensiling period. The WET hay favored the growth of molds during storage, whereas CUR hay reduced their counts after 50 d of storage. For silage, mold counts were lower in WET compared with CUR after 14 d of storage, but no differences were observed after 78 d. When the ensiling period is limited to 14 d, the aerobic exposure DM losses and heating were greater for CUR silage compared with WET. However, when the ensiling period was extended to 78 d, no differences were observed between WET and CUR silage in terms of aerobic exposure DM losses and heating degree days. Extended wilting in hay preserved ruminal in vitro DM fermentation kinetics compared with insufficient wilting, whereas the ruminal DM fermentation kinetics of silage were not affected by the wilting extent. For both conservation methods, insufficient wilting reduced methane yield only at the end of storage. The in situ rumen degradability kinetics showed that ensiling decreased the potentially degradable DM and CP fractions compared with haymaking. Haymaking reduced the ruminal degradation rate of DM but not of CP, compared with ensiling. Wilting was more critical for silage than hay in decreasing the concentration of formononetin and biochanin A. Across storage stages, hay had lower formononetin and biochanin A than silage. Overall, wilting red clover further helps conserve the nutritional quality of hay and silage while reducing phytoestrogen levels.</p>","PeriodicalId":354,"journal":{"name":"Journal of Dairy Science","volume":" ","pages":""},"PeriodicalIF":3.7,"publicationDate":"2025-06-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144273877","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Feasibility of energy dispersive X-ray fluorescence for quantitative prediction of elemental profile in untreated bovine colostrum.","authors":"D Martini, M De Marchi, A Goi, M Pozza, G Niero","doi":"10.3168/jds.2025-26391","DOIUrl":"https://doi.org/10.3168/jds.2025-26391","url":null,"abstract":"<p><p>Colostrum is the first secretion produced by the mammary gland after calving, providing essential macronutrients and micronutrients to newborns. Monitoring elemental concentrations in bovine colostrum (BC) is crucial, as it serves for the physiological development and health of the neonates. Current gold-standard methods to determine elemental composition of BC are inductively coupled plasma optical-emission spectrometry or inductively coupled plasma MS. These techniques, however, are time-consuming, expensive, labor-intensive, and destructive, and they require sample preparation such as chemical matrix decomposition. In this view, energy dispersive X-ray fluorescence (ED-XRF) could represent a handy alternative. This study evaluated the effectiveness of ED-XRF for the prediction of Na, Mg, P, S, K, Ca, and Zn in BC measured through inductively coupled plasma optical-emission spectrometry as reference method. The performances of ED-XRF in predicting BC elemental composition were assessed on the entire dataset (comprising 160 samples of individual BC), on a training set (comprising 70% of the samples), and on a testing set (comprising 30% of the samples). The models demonstrated satisfactory goodness of fit for S (coefficient of determination in external validation, R²_TE = 0.77) and Zn (R²_TE = 0.74), indicating their suitability for rough screening of such elements, while showing lower association for Na, Mg, P, K, and Ca. Results of the present study could support the development of rapid screening approaches to assess S and Zn levels in BC, contributing to more informed supplementation strategies of such minerals for calves, thereby preventing deficiencies and supporting neonatal development.</p>","PeriodicalId":354,"journal":{"name":"Journal of Dairy Science","volume":" ","pages":""},"PeriodicalIF":3.7,"publicationDate":"2025-06-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144273879","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Residual feed intake in Saanen dairy goats: Variability and repeatability from growth to lactation.","authors":"J L Kirkham, F Zamuner, A W N Cameron, B J Leury, A Carroll, K DiGiacomo","doi":"10.3168/jds.2025-26303","DOIUrl":"https://doi.org/10.3168/jds.2025-26303","url":null,"abstract":"<p><p>This experiment investigated the variability and repeatability of residual feed intake (RFI) in growing and lactating dairy goats, aiming to assess its potential as a selection tool for feed efficiency. During the growth phase, 60 5-mo-old Saanen doelings were grouped based on genetic potential for milk production: high-index (HI; n = 30) and low-index (LI; n = 30) doelings were used. During the lactation phase, 53 early-lactation does, also selected for HI and LI, were used. Of these 53 lactating does, 28 were from the growth phase to investigate the repeatability of RFI rankings. Individual feed intake, ADG, and BCS were recorded during both phases (49 d, plus 7-10 d acclimatization). On 4 occasions, plasma was collected for analysis of metabolic markers. During lactation, milk volume was recorded twice daily, and milk samples were collected twice per week for composition analysis. Goats were classified into high (<-0.5 SD from the mean of RFI), low (>+0.5 SD), and medium (between ± 0.5 SD), and efficiency groups based on RFI for both phases. The RFI variability was greater during lactation (-0.38 to 0.50 kg of DM/d) compared with growth (-0.16 to 0.17 kg of DM/d). During growth, high-efficiency goats consumed 0.18 kg/day less DM for similar production outcomes, with a mean DMI (±SD) of 1.1 ± 0.2 kg/d and an ADG of 226 ± 45 g/d. Lactating goats averaged (mean ± SD) a DMI of 2.6 ± 0.5 kg/d, ECM of 3.4 ± 0.8 kg/d, and an ADG of 139 ± 65 g/d, with high-efficiency goats maintaining reduced feed intake without compromising milk production. No significant correlation between RFI rankings in growth and lactation phases were observed, indicating limited repeatability in RFI ranking across life stages. The variability in RFI across growth and lactation, along with its independence from production traits, highlights its potential as a selection tool for improving feed efficiency in dairy goats. Further investigation into the causes of divergence in RFI and understanding the metabolic and physiological mechanisms is needed to define a more robust trait for selecting more feed-efficient animals.</p>","PeriodicalId":354,"journal":{"name":"Journal of Dairy Science","volume":" ","pages":""},"PeriodicalIF":3.7,"publicationDate":"2025-06-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144273882","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Evaluation of intramammary infection status in dairy heifers using cisternal and teat end sampling techniques.","authors":"Alyssa I Novo, J R Middleton, S E Poock, P R F Adkins","doi":"10.3168/jds.2024-26107","DOIUrl":"https://doi.org/10.3168/jds.2024-26107","url":null,"abstract":"<p><p>Intramammary infections occur commonly in dairy heifers; however, there is a lack of understanding regarding the onset and occurrence of IMI in nulliparous heifers during varying stages of development. The objectives of this study were to (1) determine at what age or stage of gestation heifer mammary samples are culture positive, (2) compare the bacterial genera and species found among sample types, (3) assess the potential of using a needle-based mammary gland sampling technique in heifers, and (4) use novel, multimethod diagnostic criteria to more comprehensively define heifer IMI (hIMI) occurrence. An observational cross-sectional study was conducted in which 304 quarters from 152 Holstein dairy heifers between the ages of 6 to 24 mo were sampled. A more rigorous definition of IMI in nulliparous heifers, hIMI, was used to quantify hIMI occurrence. This definition is comprehensive, primarily defined by the culture results of conventionally collected mammary secretions and aspirated mammary secretions or mammary tissue aspirates. Teat canal swabs and mammary skin swabs served as secondary sample types to minimize the influence of skin and teat canal flora on the results of primary sample types. Overall, 304 teat canal swabs, 93 conventionally collected mammary secretions, 304 mammary skin swabs, 43 aspirated mammary secretions, and 257 mammary tissue aspirate samples were collected, of which 24.7% (75), 39.8% (37), 34.5% (105), 48.9% (23), and 10.1% (26) were culture positive, respectively. The most common bacteria identified among all sample types, except mammary skin swabs, were staphylococci, primarily non-aureus staphylococcal and mammaliiococcal species, from both primigravid and nulligravid heifers. The overall hIMI occurrence was 28.5% (43/151) of heifers and 18.1% (54/298) of quarters. The highest proportion of quarter-level infections was seen in the mid-gestation group (42.5%, 17/40), followed by the late gestation group (35.7%, 10/28) and the early gestation group (23.1%, 12/52). The mature (11-16 mo) nulligravid heifers and young (6-10 mo) nulligravid heifers had similar quarter-level hIMI occurrence of 7.8% (7/90) and 9.1% (8/88), respectively. Overall, this study furthers the understanding of when hIMI occur, the bacterial genera and species involved, and provides results based on specific sampling methods that may prove useful for future studies evaluating hIMI status.</p>","PeriodicalId":354,"journal":{"name":"Journal of Dairy Science","volume":" ","pages":""},"PeriodicalIF":3.7,"publicationDate":"2025-06-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144273878","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Simultaneous quantification of oxyclozanide and levamisole in milk via ultra-high-performance liquid chromatography tandem mass spectrometry: A validated high-sensitivity approach for veterinary residue surveillance.","authors":"G Dai, K Sun, Y Zhou, B Li, Q Wang, Y Qiu, X Peng, X Zhou, J Zhang","doi":"10.3168/jds.2025-26722","DOIUrl":"https://doi.org/10.3168/jds.2025-26722","url":null,"abstract":"<p><p>This study developed a novel analytical method integrating liquid-liquid extraction with solid-phase extraction for simultaneous detection of oxyclozanide (OXY) and levamisole hydrochloride (LMS) residues in milk using ultra-high-performance liquid chromatography tandem MS (UPLC-MS/MS). Method validation demonstrated exceptional sensitivity with detection limits of 1.00 ng/mL and quantitation limits of 3.00 ng/mL for both analytes. Low matrix effects (CV <8.00%) and satisfactory recoveries (OXY: 84.00%-108.77%, relative SD [RSD]: 2.20%-8.00%; LMS: 89.50%-119.60%, RSD: 2.10%-8.36%) were achieved across multiple validation parameters, while sample stability remained consistent under varied processing conditions (CV <10.00%). Analysis of 120 commercial milk samples revealed no detectable residues, confirming both the reliability of this monitoring framework and the compliance of Chinese dairy products with international safety standards. As the first reported method enabling concurrent detection of this antiparasitic drug combination, the established protocol provides crucial technical support for veterinary drug residue surveillance, ensuring safer application of compound oxyclozanide suspension in livestock husbandry.</p>","PeriodicalId":354,"journal":{"name":"Journal of Dairy Science","volume":" ","pages":""},"PeriodicalIF":3.7,"publicationDate":"2025-06-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144273883","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}