Journal of Dairy Science最新文献

We compared the effects of silage from a tall-stature corn (TSC) hybrid with silage from a new short-stature corn (SSC) hybrid (due to a brachytic mutation) on DMI, feeding behavior, nutrient digestibility, and performance of lactating Holstein dairy cows. A total of 24 cows (12 per group) received identical diets for 2 wk and were then stratified according to BW, parity, DIM, and average milk production and randomly assigned to the TSC group or the SSC group. Data were collected for 70 d. Data from cows were analyzed as a completely randomized design using a mixed model procedure, and week of treatment was the repeated measure. The fixed-effects model included diet (D), week (W), and their first-order interaction (D × W), and each cow was considered a random effect. During the week before administering the experimental diets, cows in the TSC group (3.3 ± 1.5 lactations; 643 ± 61 kg BW; 85 ± 34 DIM; 47.1 ± 5.5 kg milk yield [MY]) and the SSC group (3.3 ± 1.7 lactations; 621 ± 45 kg BW; 82 ± 31 DIM; 47.1 ± 6.9 kg of MY) had similar characteristics. The 2 diets had the same CP, NDF, starch, and sugar content on a DM basis. The feeding behavior, rumination time, apparent nutrient digestibility, milk yield and composition, cheese yield traits, BW, and immune-metabolic parameters were measured for 70 d. The SSC silage had greater NDFD_30h (66.7%NDF vs. 60.6%NDF) and a greater level of starch (30.3%DM vs. 28.4%DM) than the TSC silage. These 2 differences corresponded to an increased energy content of the SSC silage (1.47 vs. 1.40 Mcal/kg DM as NEL3X). Analysis of feeding behaviors demonstrated that the SSC group had a lower DMI (25.0 vs. 26.8 kg DM/cow/d), greater meal frequency (8.3 vs. 7.4 meals/cow/d), and larger meal size (3.8 vs. 3.2 kg DM/meal). Cows in the SSC group also produced more milk (44.7 vs. 42.9 kg/cow/d) compared with TSC. The 2 groups had similar cheese yield traits. These results suggest that the brachytic corn hybrid has potential as an alternative source of high-energy corn silage for dairy farmers because it satisfies the energy requirements of lactating dairy cows and leads to improved milk production.

Whey protein is commonly used to prevent sarcopenia in older adults due to its high digestibility and amino acid content. Its bioactive components may also influence the gut microbiota, which plays a growing role in healthy aging as microbial composition shifts with age. This study investigated whether daily supplementation with whey protein isolate (WPI) improves gut microbiota diversity and composition in older adults. Sixteen participants consumed 59 g of WPI (35 g of protein) daily for 3 wk. Whey protein isolate significantly increased Simpson diversity in individuals with low baseline diversity, with effects appearing by d 3 and persisting after intervention. Taxonomic analysis revealed increases in beneficial taxa (e.g., Ruminococcaceae, Faecalibacterium, and Christensenella) and reductions in potentially harmful groups (e.g., Proteobacteria, Streptococcaceae, and Colidextribacter), particularly in the low diversity group. ANCOM-BC analysis based on absolute abundance confirmed increases in probiotic genera including Lactobacillus, Lactococcus, and Christensenella. Despite these microbial shifts, no significant changes were observed in gastrointestinal symptoms or stool consistency. These findings highlight the potential of WPI supplementation as a dietary strategy to promote a healthier gut microbiome in older adults, particularly in those with low baseline diversity.

The spread of the highly pathogenic avian influenza (HPAI) H5N1 virus in dairy cattle, particularly affecting the mammary glands, highlights the adaptability of influenza A viruses (IAV) to infect nontraditional species. Mammals like pigs, sheep, goats, and camelids contribute >$30 billion annually to the US economy and are a source of meat and milk for millions, highlighting the importance of understanding viral susceptibility in these species. The zoonotic transmission of HPAI H5N1 to several dairy and poultry farm workers involved with farm operations during outbreaks is also a cause for public health concerns. Previous studies showed IAV-specific sialic acid (SA) receptors in the mammary glands of dairy cattle, but those studies did not explore their presence in pigs, sheep, goats, alpacas, and humans. The current study used lectin histochemistry staining with fluorescently labeled Sambucus nigra (SA α2,6-galactose [gal] receptors) and Maackia amurensis (SA α2,3-gal receptors) and found that the mammary glands of all of these species, including human breast, were rich in SA α2,6-gal receptors essential for mammalian-adapted IAV binding. We also found SA α2,3-gal receptors in the examined tissues of all species, although to a lesser extent. Notably, an A(H5N1) clade 2.3.4.4b virus demonstrated binding to both ruminant (cattle) and nonruminant (pigs) species' mammary tissue. These findings provide crucial insights into the potential for HPAI H5N1 to infect and spread within the mammary glands of these production animals, as well as humans.

Fats are considered effective in reducing enteric methane (CH₄) emissions in ruminants, but limited research exists on the use of flaxseed fatty acids for this purpose in Holstein dairy cows. We evaluated the effects of an extruded flaxseed-based supplement that included a mix of flaxseed, peas, and alfalfa hay (LinPRO-R) on enteric CH₄ emissions and milk quality. Holstein cows (n = 24, 113 ± 31 DIM) were arranged in a 3 × 3 Latin square design and assigned to one of the 3 treatments: control (CON), ration containing 4.5% LinPRO (4.5% LinPRO-R), or ration containing 9% LinPRO (9% LinPRO-R) on a DM basis. In the 9% LinPRO-R group, cottonseed was replaced with the flaxseed supplement; therefore, the fatty acid profile was altered, and the forage NDF increased with higher inclusion. However, the total fat content of different diets remained similar. After 2 wk of adaptation, each of the experimental periods lasted for 28 d. Milk yield and enteric emissions were captured daily. Weekly milk samples were analyzed for milk fat, protein, lactose, SNF, MUN, and SCC. All data were analyzed using a mixed model ANOVA in the GLIMMIX procedure in SAS (SAS Institute Inc.). Body weight change, DMI, and milk yield did not differ among the different LinPRO-R treatments. Milk fat percentage was lower in LinPRO-R supplemented cows compared with the CON group (CON: 4.67 ± 0.14%, 4.5% LinPRO-R: 4.47 ± 0.14%, and 9% LinPRO-R: 4.51 ± 0.14%), but milk protein, lactose, SNF, MUN, and SCC were unaffected. Methane and CO₂ emissions did not differ among treatments, whereas H₂ production was lower in CON than in 9% LinPRO-R (CON: 4.42 ± 0.14 g/d, 4.5% LinPRO-R: 4.66 ± 0.14 g/d, and 9% LinPRO-R: 4.88 ± 0.14 g/d). The percentage of cis-9 C18:1 in milk fat was higher in the 9% LinPRO-R group compared with the CON and 4.5% LinPRO-R groups. The percentage of C18:3n-3 was greater in LinPRO-R-supplemented cows (CON: 0.52 ± 0.03%, 4.5% LinPRO-R: 1.05 ± 0.03%, and 9% LinPRO-R: 1.46 ± 0.03%). Therefore, supplementation of Holstein cow diets with 4.5% and 9% LinPRO-R did not affect milk yield or enteric CH₄ emissions, likely due to alterations in forage NDF content and the dietary fatty acid profile.

Pseudomonas fluorescens is one of the common psychrophilic bacteria in liquid milk. The thermostable enzymes produced by P. fluorescens are an important cause of changes in quality and flavor of liquid milk during storage. In this study, 3 thermostable proteases derived from P. fluorescens, neutral metalloproteinase (Nm), extracellular alkaline metalloprotease AprA (AprA), and metalloprotease AprX (AprX), were added separately to liquid milk. The upper layer protein content of the 3 groups of samples continued to decline and the lower layer protein content first increased and then decreased. The upper layer fat content in AprA and AprX groups initially decreased then increased, while the lower layer fat content showed the opposite trend. In the Nm group, upper layer fat continued to decline and lower layer fat steadily rose. Meanwhile, the particle size, acidity, and viscosity of all the samples in the 3 groups increased and showed gelation. Hydrolyzed liquid milk produced color deterioration, exhibited a bitter and sour taste, and the main odor was attributed to methyl groups, ketones, and acids. Proteomic analysis revealed AprA had an obvious hydrolysis effect on liquid milk, generating numerous κ-CN fragments (Q95100, E7E1P7, K9ZUL) in accumulated proteins. This study highlights the role of thermostable proteases in accelerating quality deterioration of liquid milk, providing a theoretical basis for controlling psychrophilic bacterial thermostable enzymes.

This study aimed to estimate the association of udder health and herd management practices with bulk tank SCC (BTSCC) and the partial costs of subclinical mastitis (milk yield losses and penalties) on dairy farms in Uruguay. As part of a cross-sectional study, a survey on udder health and herd management practices was conducted on 190 randomly selected dairy farms stratified by region and milk shipment volume (MSV). Herd data comprising 13 mo of BTSCC and MSV were obtained from the dairy processing company, and BTSCC values exceeding 250 × 10³ cells/mL (BTSCC >250) were identified. Multivariable regression models were developed to evaluate the association between udder health and herd management practices and 4 response variables on a monthly basis: BTSCC, BTSCC >250, milk yield losses, and penalties. In addition, we calculated the population attributable fraction (PAF) of practices associated with BTSCC >250 and their attributable cost. Postmilking teat disinfection (78%) and dry-cow therapy (80%) showed the highest adoption rates. Some practices such as culling of chronically infected cows based on records (11%), the use of automatic cluster removers (22%), the maintenance of calving areas (24%), monthly individual SCC (ISCC; 16%), and a monthly Californian Mastitis Test (CMT) on all cows (10%) showed low adoption rates. When adoption rates differed across MSV levels, small farms consistently had lower uptake. The lack of use of postmilking teat disinfection was associated with a higher BTSCC (30 ± 11 × 10³ cells/mL), higher odds of BTSCC >250 (odds ratio = 2.45), and higher milk yield losses ($1.22 ± 0.45 per cow per month). Similarly, farms that manually removed clusters showed higher BTSCC (29 ± 13 × 10³ cells/mL), higher odds of BTSCC >250 (odds ratio = 2.73), and higher penalties ($0.67 ± 0.28 per cow per month). For monthly ISCC, the odds of BTSCC >250 and the milk yield losses and penalties were lower, whereas on farms with maintenance of calving areas, the odds for BTSCC >250 and the penalties were lower. The partial cost of subclinical mastitis was $9.2 ± 3.9 per cow per month. Yield losses comprised 88% of the cost, and variability among farms was high. Practices associated with BTSCC >250 (postmilking teat disinfection, use of automatic cluster removers, monthly ISCC, and maintenance of calving areas) showed high PAF values. Our results highlight opportunities, some with a potential population effect, to reduce subclinical mastitis and increase overall farm profitability, particularly on smaller farms, and underscore the potential benefits of improved udder health management in Uruguay.

This study aimed to investigate the effect of dietary supplementation with docosahexaenoic acid-rich algae oil (DHA-RAO) on blood levels of selected docosahexaenoic acid (DHA) metabolites, and to assess its potential influence on cytokine production by white blood cells in neonatal dairy calves. Twenty clinically healthy Holstein male calves (8.1 ± 2 d old and 46.6 ± 4.2 kg, mean ± SD) were allocated into 2 experimental groups of 10 animals each: (1) not supplemented with DHA-RAO in milk replacer (MR; group CON); and (2) supplemented with 7.5 g of DHA-RAO/d in MR (group SUP). Calves were fed 6 L of MR/d with or without supplementation for 4 wk. The estimated DHA intake in the SUP group was 2.53 g/d. The MR intake and fecal score were recorded daily, and BW was recorded weekly. Blood samples were collected for complete blood count, measurement of DHA metabolite levels (D-series resolvins 1-4 and neuroprotectin D1), and whole blood immunostimulation assay. White blood cells were isolated from blood after ex vivo mitogen stimulation and analyzed for mRNA expression of pro- and anti-inflammatory cytokines. Supplementation of DHA-RAO in MR resulted in reduced ADG and lower final BW, accompanied by a tendency toward an increased blood DHA concentration. Neither the blood levels of resolvins 1-4 and neuroprotectin D1 nor the ex vivo cytokine response of mitogen-stimulated white blood cells collected at the end of the study were affected by the treatment. In conclusion, these findings suggest that although DHA-RAO may influence growth performance, its short-term supplementation does not appear to modulate systemic inflammation parameters or blood DHA metabolite levels in neonatal calves. To our knowledge, this is the first study to investigate DHA-derived specialized pro-resolving mediators in this species.

Sixty Alpine dairy goats were classified as healthy (HEAL, n = 30) or infected (INFE, n = 30) based on bacteriological culture of udder-half samples collected 7 d before dry-off. At -61 d from kidding (DFK), goats were dried off and randomly allocated to 2 homogeneous groups either receiving no treatment (15 HEAL, 15 INFE) or being treated intramammarily with 250 mg of cefazolin per half-udder (15 HEAL, 15 INFE). Milk yield, composition, and SCC were monitored at -82, 17, 45, and 80 DFK, and blood samples were collected at -66, -56, -7, and 8 DFK to assess plasma analytes. Antibiotic administration at dry-off did not affect productive performances in the new lactation or plasma analyte trends. Regardless of udder health status, lactose decreased in late lactation despite stable yield, likely due to increased SCC and mammary permeability during involution. The INFE goats had higher SCC before dry-off and higher SCS at 45 DFK. Following dry-off, plasma urea decreased across all groups, reflecting dietary changes aimed at easing milk cessation. Glucose and nonesterified fatty acids (NEFA) remained stable during the dry period. The INFE goats showed elevated plasma cholesterol at -57 DFK, suggesting transient dyslipidemia due to IMI. After kidding, all goats showed peaks in NEFA, NEFA/albumin ratio, BHB, bilirubin, and glutamate oxaloacetate transaminase, indicating body reserve mobilization and hepatic stress. Concurrently, increases in haptoglobin and ceruloplasmin, and decreases in albumin/globulin ratio and paraoxonase, reflect an acute phase response. The INFE goats showed higher reactive oxygen metabolites and thiol concentrations between -57 and 8 DFK, and elevated ceruloplasmin at -7 and 8 DFK, indicating sustained systemic inflammation. Plasma analytes could serve as effective diagnostic tools to improve the detection of subclinical mastitis in dairy goats.

This study evaluated consumer perception of clean label, complete, and sustainable as they pertained to protein products. Two online surveys (n = 485; n = 505) and 5 focus groups (n = 32 consumers) were conducted to quantitively and qualitatively investigate consumer behaviors and beliefs regarding protein-fortified products. The surveys involved agree or disagree questions, multiple choice questions, check-all-that-apply questions, maximum difference scaling exercises, open-ended questions, and sliding-scale questions to investigate clean label, natural or artificial ingredients, good source of protein, and complete protein. Focus groups were used to confirm survey findings and to create a consumer knowledge map. Consumers wanted protein products to be a good source of protein and to be complete protein, but consumers were largely uneducated on food ingredients, protein claims, protein processing, and food technologies. An all-natural product with a good source of complete protein that tastes great was the ideal protein-fortified product. Consumers did not know the definitions of "good source of protein" or "complete protein." Dairy proteins were perceived as better tasting, whereas plant proteins were perceived as more sustainable and ethical. Consumers were unfamiliar with precision fermentation or animal-free dairy protein, protein processing, and food innovation technologies.

Streptococcus uberis (S. uberis) is a leading cause of environmental mastitis globally. Ferroptosis, a cell death pathway driven by Fe²⁺-mediated lipid peroxide accumulation, with reactive oxygen species (ROS) participating in this process, is related to the mechanisms of infections caused by other pathogens inducing mastitis, such as Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). This study aims to investigate whether ferroptosis occurs in S. uberis-induced mastitis and to develop corresponding therapeutic interventions. Goat bone marrow mesenchymal stem cells (GBMSC) were isolated from a 3-mo-old healthy goat. After verification via surface marker analysis and trilineage differentiation, angiotensin-converting enzyme 2 (ACE2)-overexpressing GBMSC (GBMSC-ACE2) were generated using lentiviral vectors. In vitro, a coculture model of GBMSC, GBMSC-GFP, or GBMSC-ACE2 with goat mammary epithelial cells (GMEC) infected by S. uberis was established. Results showed that GBMSC-ACE2 effectively reduced ROS accumulation and inflammatory cytokine secretion, inhibited excessive activation of chaperone-mediated autophagy (CMA), and maintained iron metabolism homeostasis, thus alleviating S. uberis-induced ferroptosis in GMEC better than GBMSC or GBMSC-GFP. The main manifestations were: 1) inhibiting ADAM metallopeptidase domain 17 (ADAM17) and promoting ACE2 expression to suppress the Angiotensin II (Ang II)/Ang II Type 1 Receptor (AT1R)/NADPH oxidase 2 (NOX2) pathway; 2) inhibiting lysosomal associated membrane protein 2A (LAMP2A), heat shock cognate protein 70 (Hsc70), heat shock protein 90 (Hsp90) while promoting glutathione peroxidase 4 (GPX4) expression; 3) reducing intracellular Fe²⁺ accumulation; 4) delaying lipid peroxidation. In vivo, 9 lactating goats were randomly divided into 3 groups (n = 3 each): control, S. uberis-infected, and GBMSC-ACE2-treated. The experiment lasted 7 d. The GBMSC-ACE2 significantly decreased SCC, improved milk yield and quality, inhibited bacterial proliferation, enhanced ACE2 expression in mammary tissue, and alleviated ferroptosis by suppressing CMA-mediated GPX4 degradation, thus reducing damage to the blood-milk barrier and mammary tissue. In conclusion, this study suggests that GBMSC-ACE2 is a novel treatment for S. uberis mastitis, capable of inhibiting ferroptosis in mammary epithelial cells and promoting tissue regeneration.