Johne's disease (JD) control and eradication programs aim to reduce the prevalence of Mycobacterium avium subspecies paratuberculosis (MAP) infections and associated economic losses. Youngstock are particularly vulnerable to MAP infection—they can shed MAP in feces, develop antibody titers, and transmit the pathogen to pen mates. However, most JD control programs do not include youngstock in MAP testing strategies, potentially limiting their effectiveness by overlooking this transmission route. This study aimed to investigate the age at which youngstock ≤12 mo old in MAP-positive dairy herds start shedding MAP in feces and become ELISA-positive under field conditions.

Reliability (REL) is a metric used to assess how accurately breeding values are predicted. Calculating theoretical REL requires the prediction error variance from the inverse of the coefficient matrix of the mixed model equations, which is computationally intensive for large populations or complex models. In such cases, REL are approximated. In routine genetic evaluations it is not feasible to evaluate animals received between evaluation cycles. As an interim solution, these individuals would rely on indirect predictions (IP) based on SNP effects, and their associated reliability approximated based on the variance of estimated SNP effects.

Livestock methane emissions contribute to 18% of global greenhouse gas emissions. Integrating methane production into breeding goals has the potential to mitigate methane emissions and contribute to more sustainable livestock systems. To achieve this through genetic selection, large datasets of phenotypic records are required, making the use of direct measurement of methane emissions limited on a broad scale. Consequently, alternative approaches, such as using predicted methane emissions derived from more easily measured traits, have been proposed.

Residual feed intake (RFI) is a metric to identify high feed efficient (negative RFI; −RFI) and low feed efficient (positive RFI; +RFI) animals within and across cohorts. The objective of this study was to quantify and determine potential differences between the most RFI divergent cows in (1) metabolites, hormones, and fatty acids in tail vessel and mammary vein blood; (2) hepatic gene expression; (3) CH4, CO2, O2, and related metrics; and (4) hepatic mitochondrial function. Mid-lactation Holstein dairy cows (n = 64/trial) were enrolled in two 8-wk trials to quantify intake, BW, and milk production.

The aim of this study was to evaluate the forage feeding value of short-stature corn (SSC) genotype characterized by a brachytic2 (i.e., br2) mutation in comparison to tall-stature corn genotype (TSC) harvested at 5 different harvest moments (HM; i.e., 114, 119, 125, 135, and 149 d). In particular, 5 corn varieties selected for whole-plant silage were grown in an experimental field and harvested at 5 different HM. The field was divided into 15 experimental plots (30 m long × 4 rows × 0.75 m spacing between rows, with 1 row empty as a buffer zone); each variety was randomly seeded in 3 plots of experimental field.

Heat stress–induced liver injury is a common and potentially life-threatening complication of heat exposure in both humans and animals. With the ongoing rise in global temperatures, effective preventive strategies are urgently needed. Lactic acid bacteria have been extensively studied and shown to effectively alleviate various types of liver injury; however, their specific role in heat stress–induced liver damage remains unknown. In our previous work, we isolated Lactobacillus plantarum L19 (LP-19), a strain with strong heat resistance and antioxidant capacity, from Holstein cow milk, suggesting its potential to benefit animals and humans under heat stress.

Ensuring high-quality colostrum for newborn calves is essential for their health and future productivity. We applied Bayesian finite mixture models to estimate optimal cutoff values and evaluate the diagnostic accuracy of 3 methods—radial immunodiffusion (RID) assay, transmission infrared (TIR) spectroscopy, and digital Brix (dBrix) refractometry—measured on a continuous scale for assessing bovine colostrum quality, using 591 colostrum samples from 42 Holstein dairy herds in Atlantic Canada. The mean and standard deviation of IgG concentrations for high-quality colostrum were 61.07 ± 39.8 g/L, 51.28 ± 27.38 g/L, and 24.32 ± 4.13% Brix for RID assay, TIR spectroscopy, and dBrix refractometry, respectively, compared with 19.93 ± 15.54 g/L, 7.78 ± 37.4 g/L, and 15.87 ± 3.45% Brix for low-quality samples.

In dairy cattle farming, many traits are included in the breeding goal simultaneously to maximize economic value. The phenomenon of genetic correlations can both enhance and hinder the response to selection and has to be taken into account in multitrait selection schemes. To investigate the genetic architecture of traits included in the balanced breeding goal in Germany, multitrait meta-analyses of 11 health and 22 conformation traits in 100,809 to 180,217 German Holstein cows were conducted, followed by the estimation of global genetic correlations between each pair of traits.

Kernza straw (KS) is a high-fiber, low-energy byproduct of intermediate wheatgrass (Thinopyrum intermedium [Host] Barkworth & D.R. Dewey) that may serve as an alternative forage to increase dietary fill and reduce the risk of over-conditioning in late-pregnant heifers. We hypothesized that inclusion of KS in the diet of late-pregnant heifers would reduce feed intake and BW gain, nutrient digestibility, and urinary N excretion, but increase enteric methane production depending on the level of inclusion.

The objective of this study was to investigate the mechanistic effects of different milk-derived substrates, cow milk, goat milk, and whey protein concentrate (WPC), on the structural development, microbial succession, and metabolite production of kefir grains during 28 d of continuous subculturing. Kefir grain morphology, microbial community dynamics, and substrate-driven metabolic shifts were analyzed using scanning electron microscopy, culture- and sequencing-based microbial profiling, and untargeted metabolomics.

The aims of this study were to (1) investigate the relationships between prepartum body condition, metabolic status, dam milk variables, and colostrum yield and its immunological and nutritional components; (2) investigate the relationships between colostrum variables of dams and female offspring's growth and metabolism from birth to weaning, from weaning to calving, and during the first 100 DIM; and (3) evaluate the correlation between dam colostrum variables and their offspring after their first calving.

The objective of this study was to evaluate the effects of nitrate and Acacia mearnsii bark extract (AMT) supplementation; the latter with and without additional rumen-protected rapeseed meal (RPR), on performance, enteric CH4 emissions, and N partitioning in dairy cows fed a low-CP diet. The additional RPR aimed to counteract tannin-caused depressions of protein digestibility and potential reductions in milk production. Following a 2-wk covariate period, 18 multiparous Holstein cows were subjected to a split-plot design, with 2 main plot treatments (0.67% nitrate in dietary DM or isonitrogenous urea) and 3 subplot treatments arranged in a 3 × 3 Latin square: (1) a corn-silage-based control diet (CON; average 14.3% CP in DM), (2) CON supplemented with 3% of DM AMT containing 60% tannins (AMT), and (3) the AMT diet with an additional 6.4% of DM RPR (AMT+RPR).

The aim of this study was to characterize organic dairy systems in Brazil. It was hypothesized that the production level of the herd influences the productivity and marketing aspects of organic milk production systems. A descriptive analysis was carried out in which the variables were geographical location, herd size, animal production, feed used, health and reproduction management, organic inputs used, feed production management, and transportation of products. The characteristics of the systems were evaluated according to the level of production, with farmers divided into 3 groups, with the upper extract comprising farms with an average production of over 16 L/cow per day (HIG), the medium extract with a production between 10.5 and 16 L/cow per day (MED), and the lower extract with an average production of less than 10.5 L/cow per day (LO).

Calves that survive and thrive are important to the productivity of dairy herds through their role as potential herd replacements or as a source of livestock trading income. Conversely, calf losses are costly, leading to poorer farm productivity and welfare outcomes. Stillbirths (SB) are calvings where the calf dies near birth. Preweaning mortality (PWM) describes calves that are born alive but die before weaning. Improving SB and PWM can be achieved through conventional quantitative trait selection strategies, but these traits, especially SB, can sometimes occur because of a single large-effect recessive deleterious mutation.

Type 2 diabetes (T2D) is a global metabolic disorder influenced by diet. While cheese consumption has been suggested to protect against T2D, the mediating metabolic pathways remain unclear. Using Mendelian randomization (MR), we analyzed genetic variants associated with cheese intake (UK Biobank) and their effects on T2D risk (FinnGen) via 249 metabolites. Instrumental variables were selected under stringent criteria. Causal estimates were derived via inverse-variance weighted method, with sensitivity analyses (MR-Egger method) and mediation testing.

The objective of this randomized controlled study was to evaluate the effects of a native rumen microbial feed supplement on production performance (milk production, milk composition, and feed efficiency). Additionally, the effects of the microbial supplement on enteric methane emissions were assessed. Forty-six second-, third-, and fourth-parity Jersey cows at 59 ± 8 DIM were blocked by baseline milk yield and randomly assigned to control (no microbial supplementation) or treatment (GF-MFS; TMR containing 5 g/cow per day of a native rumen microbial feed supplement containing a minimum of Clostridium beijerinckii at 2 × 106 cfu/g, Pichia kudriavzevii at 2 × 107 cfu/g, Ruminococcus bovis at 2 × 107 cfu/g, and Butyrivibrio fibrisolvens at 2 × 107 cfu/g).

A multidimensional similarity evaluation was conducted between 12 commercial infant formulas (6 1,3-dioleoyl-2-palmitoylglycerol [OPO]-fortified samples; 6 nonfortified samples) and 205 human milk samples from Hainan Island, China, in this study. The results showed that 12 brands of infant formulas had high similarity scores to human milk at the nutrient composition and energy supply (GNE > 88), total fatty acid composition (GFA > 80), and sn-2 palmitoyl triacylglycerol (GOPO and GOPL > 82) levels.

Manufacturing cheese using only milk powders (not liquid milk) and a wheyless process could be highly beneficial for developing nations, owing to the limited availability of fresh milk and the lack of proper whey handling equipment. A wheyless process, using milk powders, is very challenging for semihard cheeses because it requires the rehydration of milk powders to very high protein levels (≥20%). The solubility and rennet coagulation properties of a range of commercial high-protein milk powders were evaluated.

Diarrhea and bovine respiratory disease (BRD) are the most common illnesses affecting calves during the preweaning period. This retrospective cohort study aimed to evaluate the associations of diarrhea and BRD with ADG, relative ADG (relADG; % of ADG relative to mid-point BW), milk replacer refusal (MRR), starter intake, and mortality in Holstein and beef-on-dairy (BxD) calves during the first 56 d of life. A total of 240 newborn calves (114 Holstein and 126 BxD) were enrolled between September 2023 and March 2024, and were housed individually for 56 d, bottle-fed with 6L/d of milk replacer and had ad libitum access to calf starter and water.

Hyperketonemia is a common metabolic disorder in early-lactation dairy cows that impairs milk performance and health. The gold-standard indicator for diagnosis is the blood metabolite BHB. However, measuring blood BHB on a large scale is cumbersome and expensive, resulting in a paucity of available phenotypes, therefore precluding hyperketonemia from most genetic evaluation systems. An alternative approach is the prediction of blood BHB concentration from milk mid-infrared (MIR) spectra. Thus, the objectives of the present study were to develop prediction equations for blood BHB concentration using milk MIR spectroscopy and to estimate genetic parameters of and among MIR-spectra-predicted BHB (MIR-BHB), milk production traits, blood BHB, and clinically diagnosed ketosis.