Agrégateur de flux

INTERPRETIVE SUMMARIES, OCTOBER 2021

Journal of Dairy Science -

Invited review: A critical appraisal of mastitis vaccines for dairy cows. By Rainard et al., page 10427. Mastitis is a major nuisance in dairy farming. Prevention through hygiene practices is laborious and would benefit from being supplemented by vaccination. Effective vaccines are wanted. This review draws up an inventory of past and present vaccines against the major pathogens of the mammary gland and reveals the reasons for their limited efficacy. This information should help in the design of new avenues of research for their improvement.

Corrigendum to “Effects of rumen-protected lysine and histidine on milk production and energy and nitrogen utilization in diets containing hydrolyzed feather meal fed to lactating Jersey cows” (J. Dairy Sci. 103:7110–7123)

Journal of Dairy Science -

Tissue energy was calculated incorrectly. The corrected equation is listed below, as well as a corrected Table 7, with corrected tissue energy (TE) and NEL values calculated using TE (corrected text shown in bold).

Corrigendum to “Effects of high-starch or high-fat diets formulated to be isoenergetic on energy and nitrogen partitioning and utilization in lactating Jersey cows” (J. Dairy Sci. 103:4378–4389)

Journal of Dairy Science -

Tissue energy was calculated incorrectly. The corrected equation is listed below, as well as a corrected Table 3, with corrected tissue energy (TE) and NEL values calculated using tissue energy (corrected text shown in bold).

Corrigendum to “Use of indirect calorimetry to evaluate utilization of energy in lactating Jersey dairy cattle consuming diets with increasing inclusion of hydrolyzed feather meal” (J. Dairy Sci. 103:4206–4217)

Journal of Dairy Science -

Tissue energy was calculated incorrectly. The corrected equation is listed below, as well as a corrected Table 3, with corrected tissue energy and NEL values calculated using tissue energy (corrected text shown in bold).

Abomasal infusion of oleic acid increases fatty acid digestibility and plasma insulin of lactating dairy cows

Journal of Dairy Science -

Our objective was to determine whether abomasal infusions of increasing doses of oleic acid (cis-9 C18:1; OA) improved fatty acid (FA) digestibility and milk production of lactating dairy cows. Eight rumen-cannulated multiparous Holstein cows (138 d in milk ± 52) were randomly assigned to treatment sequence in a replicated 4 × 4 Latin square design with 18-d periods consisting of 7 d of washout and 11 d of infusion. Production and digestibility data were collected during the last 4 d of each infusion period.

Increased super-conditioning temperature of corn grain affects performance, skeletal growth, and blood metabolites in Holstein dairy calves

Journal of Dairy Science -

We aimed to evaluate the effects of feeding super-conditioned corn at different temperatures on intake, growth performance, total-tract starch digestibility, rumen fermentation, blood metabolites, and feeding behavior of dairy calves. Thirty-six Holstein female dairy calves (40 ± 1.72 kg of body weight, ± SD) were randomly assigned to 1 of the following 3 treatments: (1) ground corn (control; CON; n = 12), (2) corn super-conditioned at 75°C (T-75; n = 12), and (3) corn super-conditioned at 95°C (T-95; n = 12).

Nuclear factor erythroid 2-related factor 2 protects bovine mammary epithelial cells against free fatty acid-induced mitochondrial dysfunction in vitro

Journal of Dairy Science -

Bovine mammary epithelial cells undergo an increase in metabolic rate, mitochondrial dysfunction, and oxidative stress after calving. Nuclear factor erythroid 2-related factor 2 (NFE2L2), a master regulator of cellular redox homeostasis, plays crucial roles in the regulation of mitochondrial function. The objective of this study was to investigate the role of NFE2L2 on mitochondrial function in bovine mammary epithelial cells under hyperlipidemic conditions. Three experiments were conducted as follows: (1) the immortalized bovine mammary epithelial cell line MAC-T was treated with various concentrations of free fatty acids (FFA; 0, 0.6, 1.2, or 2.4 mM) for 24 h to induce stress; (2) MAC-T cells were transfected with small interfering RNA targeting NFE2L2 (si-NFE2L2) and scrambled nontarget negative control (si-Control) for 48 h; and (3) MAC-T cells were pretreated with 10 μM sulforaphane (SFN), an activator of NFE2L2, for 24 h followed by treatment with 1.2 mM FFA for an additional 24 h.

Rapid and sensitive detection of Salmonella in milk based on hybridization chain reaction and graphene oxide fluorescence platform

Journal of Dairy Science -

Salmonella is a foodborne pathogen that has contributed to numerous food safety accidents worldwide, making it necessary to detect contamination at an early stage. A pair of specific primers based on the invA gene of Salmonella was designed for PCR. Target double-stranded DNA (dsDNA) from PCR was purified and denatured at high temperature to obtain target single-stranded DNA (ssDNA). Two carboxyfluorescein-labeled hairpin probes (H1-FAM and H2-FAM) were designed with complementary portions to the ssDNA sequence so that binding could trigger H1-FAM and H2-FAM hybridization chain reaction (HCR) to produce a long dsDNA complex.

Nutrient digestibility and production responses of lactating dairy cows when saturated free fatty acid supplements are included in diets: A meta-analysis

Journal of Dairy Science -

Our objective was to perform a series of meta-analyses to evaluate the effects of diets supplemented with saturated free fatty acid (FA) supplements (SFAA) compared with nonfat supplemented control diets (CON) on nutrient digestibility and production responses of lactating dairy cows and to determine whether experimental design affects responses to SFFA. We divided SFFA into C16:0-enriched supplements (PALM, FA supplements with ≥80% C16:0) and C16:0+C18:0-enriched supplements (MIX, FA supplements with ≥80% C16:0+C18:0).

Genetic analysis of milk urea concentration and its genetic relationship with selected traits of interest in dairy cows

Journal of Dairy Science -

The aim of this study was to estimate genetic parameters of milk urea concentration (MU) and its genetic correlations with milk production traits, longevity, and functional traits in the first 3 parities in dairy cows. The edited data set consisted in 9,107,349 MU test-day records from the first 3 parities of 560,739 cows in 2,356 herds collected during the years 1994 to 2020. To estimate the genetic parameters of MU, data of 109 randomly selected herds, with a total of 770,016 MU test-day records, were used.

Reducing hepatic endoplasmic reticulum stress ameliorates the impairment in insulin signaling induced by high levels of β-hydroxybutyrate in bovine hepatocytes

Journal of Dairy Science -

Ketotic dairy cows exhibit a state of negative energy balance (NEB) characterized by elevated circulating levels of β-hydroxybutyrate (BHB) and fatty acids. Impaired hepatic insulin signaling in dairy cows occurs frequently during the transition into lactation, but its role on liver function during this period is not well known. In nonruminants, endoplasmic reticulum (ER) stress is a causal factor contributing to impaired insulin signaling in the liver. Thus, the aim of this study was to investigate the status of hepatic insulin and ER stress signaling and whether ER stress contributes to impaired insulin signaling in dairy cows with ketosis.

A study of various chemical pretreatments to fractionate lipids from whey protein phospholipid concentrate

Journal of Dairy Science -

Dairy-derived lipids such as phospholipids (PL) have been gaining interest due to their functional and nutritional properties. Our research goal was to develop a separation process (nonsolvent based) to produce an enriched dairy lipid fraction from whey protein phospholipid concentrate (WPPC). Various chemical pretreatments (i.e., adjustment of pH, calcium, or temperature) were applied to rehydrated commercial WPPC solutions. These treatments were done on a bench-top scale to aid in the precipitation of proteins or PL.

Intensification strategies for temperate hot-summer grazing dairy systems in South America: Effects of feeding strategy and cow genotype

Journal of Dairy Science -

Pasture-based dairy systems present the opportunity to increase productivity per hectare through increasing stocking rate and forage utilization. However, in the temperate hot-summer region of South America, different productive strategies are being adopted by farmers. The aim of this study was to quantify the effect of feeding strategy (FS) and cow genotype (G) on individual animal and whole-farm biophysical performance. A design with 2 × 2 levels of intensification aiming to increase home-grown forage utilization and milk output per hectare was evaluated.

Invited review: Use of assisted reproduction techniques to accelerate genetic gain and increase value of beef production in dairy herds

Journal of Dairy Science -

The contribution of the calf enterprise to the profit of the dairy farm is generally considered small, with beef bull selection on dairy farms often not considered a high priority. However, this is likely to change in the future as the rapid rate of expansion of the dairy herd in some countries is set to plateau and improvements in dairy herd fertility combine to reduce the proportion of dairy breed calves required on dairy farms. This presents the opportunity to increase the proportion of beef breed calves born, increasing both the value of calf sales and the marketability of the calves.

Genomic prediction of milk-production traits and somatic cell score using single-step genomic best linear unbiased predictor with random regression test-day model in Thai dairy cattle

Journal of Dairy Science -

Cow genotypes are expected to improve the accuracy of genomic estimated breeding values (GEBV) for young bulls in relatively small populations such as Thai Holstein-Friesian crossbred dairy cattle in Thailand. The objective of this study was to investigate the effect of cow genotypes on the predictive ability and individual accuracies of GEBV for young dairy bulls in Thailand. Test-day data included milk yield (n = 170,666), milk component traits (fat yield, protein yield, total solids yield, fat percentage, protein percentage, and total solids percentage; n = 160,526), and somatic cell score (n = 82,378) from 23,201, 82,378, and 13,737 (for milk yield, milk component traits, and SCS, respectively) cows calving between 1993 and 2017, respectively.

Integration of statistical inferences and machine learning algorithms for prediction of metritis cure in dairy cows

Journal of Dairy Science -

The study's objectives were to identify cow-level and environmental factors associated with metritis cure to predict metritis cure using traditional statistics and machine learning algorithms. The data set used was from a previous study comparing the efficacy of different therapies and self-cure for metritis. Metritis was defined as fetid, watery, reddish-brownish discharge, with or without fever. Cure was defined as an absence of metritis signs 12 d after diagnosis. Cows were randomly allocated to receive a subcutaneous injection of 6.6 mg/kg of ceftiofur crystalline-free acid (Excede, Zoetis) at the day of diagnosis and 3 d later (n = 275); and no treatment at the time of metritis diagnosis (n = 275).

Effects of enzymatic hydrolysis on the allergenicity of natural cow milk based on a BALB/c mouse model

Journal of Dairy Science -

Cow milk allergy is one of the most prevalent food allergies worldwide, particularly in infants and children. To the best of our knowledge, minimal research exists concerning the antigenicity of cow milk (CM). This study was performed to evaluate the allergenicity of enzymatically hydrolyzed cow milk (HM) in a BALB/c mouse model. The mice were randomly divided into 5 groups (n = 12/group), which were sensitized with phosphate-buffered saline, CM, and HM (Alcalase-, or Protamex-, or Flavorzyme-treated cow milk; Novo Nordisk; AT, PT, FT, respectively), respectively, using cholera toxin as adjuvant on d 0, 7, 14, 21.

Effects of oral administration of timothy hay and psyllium on the growth performance and fecal microbiota of preweaning calves

Journal of Dairy Science -

The objective of this study was to evaluate the effects of oral administration of fiber from the first week of life on the growth and hindgut environment of preweaning calves. Twenty newborn female Holstein calves were divided into 2 groups as control and treatment. Calves in both groups were reared under the same feeding program except for oral fiber administration. Timothy hay and psyllium were mixed at a 50-to-6 ratio as a treatment diet for oral fiber administration. Calves in the treatment group were orally administered 50 g of fiber daily from 3 to 7 d of age and 100 g of fiber from 8 d of age until weaning.

Prophylactic use of an ultra-diluted complex on health, metabolism, and performance of weaned Holstein calves and its carryover effect up to first lactation

Journal of Dairy Science -

The objective of this study was to evaluate the effect of an ultra-diluted complex supplemented as a prophylactic strategy on the incidence risk of diseases, metabolism, and performance of weaned Holstein calves immediately after grouping. Additionally, the objective was to investigate the carryover effects on heifer-raising and first-lactation periods, in a double-blind, placebo-controlled trial. A total of 184 weaned Holstein calves (83 ± 7.9 d of life; 112.5 ± 11.7 kg of body weight; values are mean ± standard deviation) were allocated to 8 paddocks in a completely randomized block design experiment.

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