Journal of Dairy Science最新文献

Cow-calf contact (CCC) systems are of growing scientific interest due to the public concern about early separation of the calf from the dam on dairy cattle farms, which currently occurrs soon after calving. Despite the scientifically demonstrated beneficial effects of CCC for both the cow (improving udder health and promoting maternal behaviors) and calf (growth, social learning and reduction of abnormal behaviors), only a small number of dairy cattle farmers practice CCC. Although unpredictable, new animal welfare legislation or best practice guidelines might suggest the adoption of CCC systems in the future. Therefore, the aim of this review is to identify common barriers that prevent farmers from implementing CCC systems and suggest suitable strategies to overcome them. Thus, this review focuses first on identifying barriers that prevent farmers from choosing CCC or transitioning to CCC, considering influencing factors such as region, demographics, and farm characteristics. Second, the review proposes suitable research and knowledge transfer strategies (i.e., communication, dissemination, and education) to address these barriers. For the proposal of research strategies, an overview of mother-offspring management strategies used in other livestock production systems (e.g., beef cattle and dairy sheep) that could potentially be used by dairy cattle farmers to implement CCC systems is provided. The results show that many dairy cattle farmers without CCC experience expressed concerns about the effects of CCC on economic viability, management and staff wellbeing, and animal welfare. However, farmers who practice(d) CCC reported generally positive experiences and did not confirm some of the concerns raised by farmers without CCC experience. This implies that these concerns are knowledge barriers that could be addressed with effective knowledge transfer strategies. Nevertheless, there were also concerns (e.g., separation distress) that were confirmed by farmers who practice(d) CCC, suggesting that these practical barriers require the exploration of novel strategies. Despite differences in biology or productive values, inspiration could be drawn from mother-offspring management in other livestock systems. For instance, future research on dairy cattle could explore the efficacy of restricted suckling to increase milk yield, as well as the efficacy of keeping calves together with familiar peers to reduce separation distress. Combined with research into economic viability and effective knowledge transfer, insights from other livestock systems could improve the implementation of CCC systems in a way that is sustainable for dairy cattle farmers, beneficial for the welfare of cows and calves, and socially acceptable.

Our objective was to investigate sucrose replacement in school lunch chocolate milk with nutritive and non-nutritive sweeteners, with and without lactose hydrolysis of milk, on adult and child acceptance. In experiment 1, chocolate milk was formulated with nutritive and non-nutritive sweeteners (allulose syrup, mixed-sugar syrup, stevia, monk fruit, or sucralose) to the iso-sweet intensity of a current school lunch chocolate milk formulation with 3.69% sucrose (wt/vol). In experiment 2, lactose-hydrolyzed (LH) chocolate milk was formulated with nutritive and non-nutritive sweeteners (allulose syrup, mixed-sugar syrup, stevia, monk fruit) to the iso-sweet intensity of 3.69% sucrose (wt/vol). In experiment 3, LH chocolate milk was formulated with sweetener blends of allulose syrup, monk fruit, and stevia to the iso-sweet intensity 3.69% sucrose (wt/vol). Iso-sweetness for all experiments was determined using magnitude estimation scaling and confirmed by 2-alternative forced-choice paired comparison tests. Sensory properties of chocolate milks in each experiment were documented by descriptive analysis (DA) and temporal dominance of sensations (TDS). Consumer acceptance of chocolate milks was evaluated by adult consumers for all experiments, and by child consumers for experiment 3. Sweeteners in unhydrolyzed chocolate milk (experiment 1) were differentiated (P < 0.05) from the sucrose control chocolate milk due to bitter and metallic tastes inherent in the sweeteners. Liking scores for chocolate milks sweetened with allulose syrup, mixed-sugar syrup, and sucralose were not different (P > 0.05) from the sucrose control chocolate milk, whereas liking scores for chocolate milks sweetened with stevia and monk fruit were lower than the sucrose control (P < 0.05). Lactose hydrolysis (experiment 2) enhanced sweetness, reducing the required sweetener concentration by approximately one-third. Consumer acceptance of LH chocolate milks with different sweeteners were not different (P > 0.05). The application of sweetener blends in LH chocolate milk resulted in minimal differences by DA and TDS, and no differences (P > 0.05) in overall liking compared with the sucrose control chocolate milk among adult and child consumers (experiment 3). These findings demonstrate that combining lactose hydrolysis with non-nutritive sweetener blends can effectively replicate the sensory profile of sucrose-sweetened chocolate milk, offering a lactose-free, no-added-sugar alternative suitable for school lunch programs. This approach may help manufacturers meet nutritional goals while maintaining consumer appeal.

Silage is a major component of dairy diets worldwide, but the effects of storage temperature (ST) on the nutrient composition, fermentation profile, and aerobic stability of silage remain unclear. Our objectives were to (1) evaluate the effects of storage temperature on nutritive value and fermentation profile of silage, and (2) assess the effects of ST on nutritive value, fermentation profile, and aerobic stability of whole-plant corn silage (WPCS). Data from 42 peer-reviewed articles met the selection criteria, with a total of 253 treatment means. For WPCS, a secondary meta-analysis with data from 15 articles met the selection criteria, with a total of 96 treatment means. Silage was classified by type, storage length, and temperature range. Storage temperatures were categorized into 10°C increments: (1) ≤10°C; (2) >10 and ≤20°C; (3) >20 and ≤30°C; (4) >30 and ≤40°C; and (5) >40°C. Data were analyzed using a mixed-effects model with ST as a fixed effect and treatment (other than ST) within study as a random effect. Both storage length and silage type were fitted as continuous and categorical covariates in the model, respectively. For the WPCS subset, silage type classification was not included in the model. The pooled SEM for response variables per study was included as a weighting factor for the data and calculated as the inverse of the square of the variance. Means were determined using the LSMEANS statement and were compared using the sequentially rejective Bonferroni t-test adjustment. Increasing ST impaired silage fermentation by reducing lactic acid bacteria (LAB) counts. Conversely, lower temperatures (≤10°C) restricted silage fermentation due to lower acid production and altered metabolic activity of LAB. For WPCS, increasing ST gradually increased DM losses, and greater ethanol production was observed for silage stored at 11 to 20°C than at 31 to 40°C. Overall, moderate temperatures (21 to 30°C) may be more suitable for silage storage due to greater acid production, rapid pH decline, and lower DM losses. In addition, changes in fermentation profile across ST ranges indicate a potential shift in dominant bacterial species during ensiling. These findings can provide useful information about silage production for dairy farmers. In cold climates, producers should allow longer storage times to ensure adequate fermentation, and the use of inoculants capable of stimulating fermentation at low temperatures may provide additional benefits. Conversely, in warm or tropical regions, rapid silo sealing and careful face management are important to prevent excessive heating and nutrient losses during feed-out.

Staphylococcus aureus is a major pathogen responsible for both clinical and subclinical bovine mastitis. Its ability to persist within the mammary gland and evade host immune responses makes it particularly significant for herd health and dairy production. So, this study aimed to evaluate whether the presence and diversity of S. aureus virulence genes mastitis-causing are associated with the onset and severity of mastitis in dairy cows. We analyzed 50 S. aureus isolates obtained from milk samples of cows with subclinical mastitis (SM) and 101 isolates from clinical mastitis (CM), including 28 from mild and 73 from moderate cases. These isolates were screened for genes encoding enterotoxins (sea, seb, sec, sed, see, seg, seh, sei, and sej), biofilm production (bap, icaA, and icaD), toxic shock syndrome toxin (tsst-1), Panton-Valentine leukocidin (pvl), and microbial surface components recognizing adhesive matrix molecules (fnbA, fnbB, fib, clfA, clfB, cna, eno, and ebpS). In addition, pulsed-field gel electrophoresis (PFGE) was used to differentiate the genetic profiles associated with the various disease presentations. The CM isolates presented 16 out of 22 (72.7%) virulence genes compared with 14 (63.6%) in SM isolates. Regardless of mastitis severity, icaD (99.3%), eno (98%), and clfA (78.8%) were the most frequently observed, and seb and sej were not found. Our results also revealed that the virulence genes significantly associated with CM were fnbA, fib, clfA, clfB, cna, ebpS, seg, seh, sei, bap, and icaA. The PFGE revealed that no single cluster included isolates causing both CM and SM. However, CM clusters contained isolates from both mild and moderate mastitis cases. Although the host is a significant variable in the development of mastitis, our findings demonstrate that the virulence profile can play a crucial role in disease progression, as further supported by PFGE results, which showed a distinct separation between CM and SM clusters.

A meta-analysis was conducted to quantify production responses to chromium (Cr) supplementation and better understand variables that affect this response. Multivariate random and mixed effects models were used to develop and fit all models. The response variable was described by the mean difference of milk yield, ECM, DMI, and milk fat and protein yields between cows that received Cr supplementation and cows in the control group. Treatment means from 28 studies were used to assemble a database of studies designed specifically to investigate the effects of supplementing Cr on dairy cows. Of the 93 treatment means, 38 means fed the Cr starting in the dry period. Overall, Cr supplementation increased production, and the mean difference is affected by stage of lactation (characterized by DIM in our analysis), Cr source (Cr-methionine, Cr-propionate, Cr-chelate, Cr-picolinate, Cr-yeast), and dose (0-19 mg/d). The models for milk yield, milk fat, and milk protein suggest the greatest response for Cr supplementation between a 6 to 7 mg/d supplementation rate. However, the greatest response for DMI was predicted to be at a supplementation rate of 9 mg/d. The models suggest peak mean differences in yields of milk, ECM, fat, and protein at approximately 100 DIM with supplementation of Cr starting at pre- or postcalving. Although the production of ECM maximizes at approximately 100 DIM there is still a benefit in production to feeding Cr up to 168 to 186 DIM, depending on the Cr source.

The SLICK1 genetic variant, originally identified in Senepol cattle, enhances heat tolerance in association with a short hair coat. The improved heat tolerance is linked to an increased ability to lose heat, which may lead to increased cold susceptibility in colder, winter environments. Our objective was to measure the thermoregulatory responses of Friesian-Jersey crossbred SLICK1 carriers and control calves during short-term, controlled, cold challenges over 2 yr. These were allocated into groups of 4 (2 slicks and 2 controls), penned individually, and subjected to acute cold temperatures (-4.5°C) for 6 h with a dry coat and repeated with a wet coat at 1 wk of age (n = 12 slicks vs. 12 controls) and at 5 wk (n = 12 slicks vs. 12 controls). Behavioral observations (lying, shivering, and piloerection), rectal temperature and skin (eye, nose, rump, leg) surface temperature were measured pre- (baseline) and post- (recovery) experiment and at hourly intervals during the cold challenge. Temperature data were analyzed using a repeated measures mixed model. The skin surface temperatures (eye, nose, rump, and leg) remained similar between the genotypes and relatively stable (after an initial fall) throughout the 6 h cold challenges in wk 1, with no differences observed between treatments (dry or wet coats). The temperature of the eye surface showed the smallest change (∼-1 to 2°C) at both 1 and 5 wk. A reduction in rectal temperature of <0.25°C was recorded over the first 2 h of the cold challenge at 1 and 5 wk with no difference attributable to genotype or dry/wet treatment. All calves returned to baseline temperatures within 1 h following removal from the cold environment and feeding warm milk. Slick calves were more often seen shivering during the cold challenge relative to control calves at both 1 and 5 wk of age. The frequency with which shivering was seen was lower in control calves at 5 wk of age but remained high in slick animals. All calves showed an increased frequency of lying at 1 wk of age relative to 5 wk. No difference was observed between genotypes in the frequency of piloerection. Hair length measured at the neck, shoulder, and pin bone during the first 2 wk of life was shorter overall in slick calves compared with controls (20.0 ± 4.3 vs. 26.4 ± 6.4 mm). Results indicate that slick calves can effectively regulate their body temperature during short-term cold exposure in a controlled environment; however, they show a greater inclination to shiver, relative to control calves.

Bovine mastitis caused by Klebsiella pneumoniae is an infectious disease characterized by severe clinical manifestations, poor therapeutic outcomes, and substantial economic losses. Although type 1 fimbriae, with fimA as the major structural subunit, are a recognized virulence factor in Enterobacteriaceae, their specific role in bovine mastitis remains unclear. In this study, we constructed a ΔfimA mutant from a clinical mastitis isolate to evaluate contributions of fimA to adhesion and virulence. Transmission electron microscopy revealed impaired fimbrial assembly in the mutant, whereas adhesion assays demonstrated significantly reduced binding to bovine mammary epithelial cells in vitro. At the bacterial level, transcriptome analysis revealed downregulation of type 1 fimbrial genes, iron acquisition systems, outer membrane protein, and several stress-related proteins, whereas type 3 fimbrial genes and lysozyme inhibitors were upregulated, suggesting compensatory regulation of adhesion and stress responses. In an in vivo murine intramammary infection model, ΔfimA infection, compared with wild type (WT), resulted in significantly lower bacterial load, attenuated mammary inflammation, reduced histopathological damage, and decreased cytokine concentrations. Specifically, TNF-α and IL-6 were significantly reduced in ΔfimA-infected tissues, Gasdermin D (GSDMD) cleavage was significantly lower than in WT, and IL-1β and NLRP3 had downward but nonsignificant trends. In addition, quantitative real-time PCR confirmed differential expression of representative immune-related genes, supporting a weaker proinflammatory response in the absence of fimA. Collectively, these findings implicated fimA as a key determinant of fimbrial assembly, epithelial adhesion and proinflammatory activation in the mammary gland, providing new mechanistic insights into relationships among fimbriae, colonization, and virulence in K. pneumoniae.

Irish dairy systems are predominantly grass-based, with cows grazing outdoors for most of the year, making effective grassland and nutrient management central to both productivity and sustainability. Excessive nitrogen (N) fertilizer use poses environmental risks, with N surpluses potentially contributing to water pollution, making nitrogen use efficiency (NUE) a key metric of farm sustainability. Using farm accountancy data network data from 2013 to 2023, this study examines the determinants of farm gate NUE on derogation and non-derogation dairy farms, quantifying the effects of management practices, regulatory requirements, and biophysical conditions using a fixed effects panel regression model. Results indicate that derogation farms, despite higher organic N stocking rates, achieve NUE comparable to non-derogation farms, reflecting effective N management at higher intensities. Reducing total N inputs, lowering N in concentrate feed, adopting low emission slurry spreading, and using protected urea all improve NUE, whereas more productive soils further enhance efficiency. The findings highlight the importance of targeted regulation, support for voluntary mitigation practices, and nutrient management strategies tailored to soil and farm-specific conditions.

The impact of methane inhibitors on ruminant performance and rumen microbial community composition is unclear. The aim of this study was to summarize the effects of methane inhibitors on the performance of ruminants and the structure of rumen microbial communities. A total of 13,043 studies were retrieved from the Web of Science database. Ultimately, 256 studies containing the variables we needed were included. The data were further extracted and processed. The study revealed the negative effects of methane inhibitors on ruminants, which were reflected in the reduction of feed intake and digestibility in ruminants. Adding methane inhibitors reduced the acetate concentration in the rumen and increased the propionate content in the rumen. There was no significant change in the α-diversity of the rumen microbiome, whereas the β-diversity of rumen microbes was enhanced. The effects of methane inhibitor supplementation showed dose-dependent significant differences, particularly in modulating rumen fermentation parameters and the structure of the microbial community. Furthermore, when the total VFA in the rumen were below 96.98 mmol/L, or the acetate concentration was below 61.26 mmol/L, or the acetate-to-propionate ratio was below 3.86, the suppression of methane production was most effective. The addition of methane inhibitors has a positive effect on the performance of ruminants, particularly by improving the structure of the rumen microbiota. Additionally, VFA have a certain threshold effect on methane production. This provides a reference for the application and selection of methane inhibitors.