Agrégateur de flux

Interpretive Summaries, November 2018

Journal of Dairy Science -

Short communication: Daily intake of 125 g of cheese for 2 weeks did not alter amount or distribution of serum lipids or desaturase indexes in healthy adults in an exploratory pilot study. By Høstmark et al., page 9625. Dietary guidelines recommend decreased intake of regular cheese because of the fat content, but cheese also contains factors that might blunt or abolish the cholesterol-raising effect of saturated fat. Over 2 wk, 17 healthy adults added 125 g of cheese daily to their habitual diet.

Letter to the Editor: Challenging one sensor method for screening dairy cows for reduced methane emissions

Journal of Dairy Science -

Selective breeding is suggested as a mitigation strategy to reduce enteric methane (CH4) emission by dairy cows. Ranking of animals for genetic selection for low CH4 emitting potential requires reliable and cost-effective measurements from a large number of animals in farm conditions. As an international group of scientists pointed out “… the need for high throughput methodology, e.g. for screening large numbers of animals for genomic studies, does not in itself justify the use of methods that are inaccurate, imprecise, or biased” (Hammond et al., 2016).

Letter to the Editor: A response to Huhtanen and Hristov (2018)

Journal of Dairy Science -

We thank the journal for this opportunity to respond to the issues raised by P. Huhtanen and A. N. Hristov in their letter to the editor (Huhtanen and Hristov, 2018). We hope this response will resolve a persistent misunderstanding that is also reflected in the statement by Hammond et al. (2016): “… the need for high throughput methodology, e.g. for screening large numbers of animals for genomic studies, does not in itself justify the use of methods that are inaccurate, imprecise, or biased.” In this response, we will clarify that even if measurements are inaccurate, imprecise, or biased, they might provide valuable information for selective breeding.

Letter to the Editor: Comments on Rotz (2018)

Journal of Dairy Science -

There is international acceptance, supported by multilateral agreements, of the need to reduce anthropogenic sources of greenhouse gases (GHG). Dairy production systems are significant contributors to these GHG emissions, and emission reduction is a critical challenge for the dairy industry. Robust measurement of GHG emissions is fundamental to this challenge and to improving management of dairy supply chains around the world.

Use of indirect calorimetry to evaluate utilization of energy in lactating Jersey dairy cattle consuming common coproducts

Journal of Dairy Science -

The use of coproducts as an alternative feed source is a common practice when formulating dairy rations. A study using 12 multiparous (79 ± 16 d in milk; mean ± standard deviation) lactating Jersey cows was conducted over 5 mo to evaluate the effects of dried distillers grains with solubles (DDGS) or canola meal on milk and gas production. A replicated 4 × 4 Latin square design was used to compare 4 dietary treatments. Treatments comprised a control (CON) containing no coproducts, a treatment diet containing 10% (dry matter basis) low-fat DDGS (LFDG), a treatment diet containing 10% high-fat DDGS (HFDG), and a 10% canola meal (CM) treatment.

Symposium review: Genomic investigations of flavor formation by dairy microbiota

Journal of Dairy Science -

Flavor is one of the most important attributes of any fermented dairy product. Dairy consumers are known to be willing to experiment with different flavors; thus, many companies producing fermented dairy products have looked at culture manipulation as a tool for flavor diversification. The development of flavor is a complex process, originating from a combination of microbiological, biochemical, and technological aspects. A key driver of flavor is the enzymatic activities of the deliberately inoculated starter cultures, in addition to the environmental or “nonstarter” microbiota.

Prediction accuracies and genetic parameters for test-day traits from genomic and pedigree-based random regression models with or without heat stress interactions

Journal of Dairy Science -

The aim of this study was to compare genetic (co)variance components and prediction accuracies of breeding values from genomic random regression models (gRRM) and pedigree-based random regression models (pRRM), both defined with or without an additional environmental gradient. The used gradient was a temperature-humidity index (THI), considered in statistical models to investigate possible genotype by environment (G×E) interactions. Data included 106,505 test-day records for milk yield (MY) and 106,274 test-day records for somatic cell score (SCS) from 12,331 genotyped Holstein Friesian daughters of 522 genotyped sires.

Effect of diets supplemented with starch and corn oil, marine algae, or hydrogenated palm oil on mammary lipogenic gene expression in cows and goats: A comparative study

Journal of Dairy Science -

A direct comparison of cow and goat performance and milk fatty acid (FA) responses to diets that either induce milk fat depression or increase milk fat content in cows suggests species-specific regulation of lipid metabolism, including mammary lipogenesis. This experiment was conducted to highlight potential mechanisms responsible for the differences in mammary lipogenesis due to diet and ruminant species. Twelve Holstein cows and 12 Alpine goats were fed a basal diet containing no additional lipid (CTL) or a similar diet supplemented with corn oil [5% dry matter intake (DMI)] and wheat starch (COS), marine algae powder (MAP; 1.5% DMI), or hydrogenated palm oil (HPO; 3% DMI), according to a 4 × 4 Latin square design with 28-d experimental periods.

Short communication: Risk factors for sonographically detectable udder edema in overbagged cows at dairy shows

Journal of Dairy Science -

At dairy cow shows, the appearance of the udder is very important. To show cows at their best, udders are often presented in an overbagged state by extending milking intervals before the show. This practice represents an animal welfare issue because it is associated with behavior changes (e.g., excessive abduction and decreased eating time) and may affect the health of the animal. The aim of the current study was to determine the association between various parameters (e.g., milk yield, days in milk, milking procedures, or administration of nonsteroidal anti-inflammatory drugs, steroids, or diuretics) and the sonographically detectable udder edema score.

Technical note: Developing a heat stress model in dairy cows using an electric heat blanket

Journal of Dairy Science -

Precisely studying the biological consequences of heat stress (HS) in agriculturally relevant animals typically requires expensive climate-controlled facilities, infrastructure inaccessible to most researchers. Thus, study objectives were to explore the efficacy of an electric heat blanket (EHB) as an alternative method for evaluating HS and to determine whether EHB-induced hyperthermia affects production parameters similar to natural HS. Lactating Holstein cows (n = 8; 133 ± 3 d in milk; 709 ± 31 kg; 2.6 ± 0.3 parity) were housed in individual box stalls and allowed to acclimate for 3 d.

Relationships between protein and energy consumed from milk replacer and starter and calf growth and first-lactation production of Holstein dairy cows

Journal of Dairy Science -

The objective was to determine relationships between protein and energy consumed from milk replacer and starter and calf growth and first-lactation production of Holstein heifer calves. Milk replacer and starter protein intake and metabolizable energy (ME) intake data were collected from 4,534 Holstein heifer calves for growth and 3,627 Holstein cows for production from birth year of 2004 through 2014. Calves from 3 commercial dairy farms were assigned to 45 different calf research trials at the University of Minnesota Southern Research and Outreach Center, Waseca, Minnesota, from 3 to 195 d of life.

Short communication: Blood metabolites, body reserves, and feed efficiency of high-producing dairy cows that varied in ruminal pH when fed a high-concentrate diet

Journal of Dairy Science -

Recent studies report considerable variation in ruminal pH for lactating dairy cows even when fed the same diet. We hypothesized that blood metabolites would be indicators of low ruminal pH, and hence could be used as predictors to help manage this variability. The objective of the study was to determine whether blood metabolite concentrations, body reserves, and feed efficiency were associated with ruminal pH in high-producing dairy cows fed a high-concentrate diet. Seventy-eight individually fed lactating dairy cows (days in milk = 103 ± 27; body weight = 638 ± 77 kg at the start; mean ± SD) were fed a diet consisting of 35% forage and 65% concentrate (dry matter basis).

Ability of milk pH to predict subclinical mastitis and intramammary infection in quarters from lactating dairy cattle

Journal of Dairy Science -

Milk pH is increased in lactating dairy cattle with subclinical mastitis (SCM) and intramammary infection (IMI). We hypothesized that milk pH testing provides an accurate, low-cost, and practical on-farm method for diagnosing SCM and IMI. The main objective was to evaluate the clinical utility of measuring milk pH using 3 tests of increasing pH resolution, Multistix 10 SG Reagent Strips for Urinalysis (Multistix strips, Bayer HealthCare Inc., Elkhart, IN), pH Hydrion paper (Microessential Laboratory, Brooklyn, NY), and Piccolo plus pH meter (Hanna Instruments, Woonsocket, RI), for diagnosing SCM and IMI in dairy cattle.

Genetic evaluation of gestation length and its use in managing calving patterns

Journal of Dairy Science -

Data collected from Australian Holstein cows that calved between 1995 and 2016 were used for estimating genetic parameters and genetic evaluation of gestation length (GL). Genetic parameters were estimated using a sire maternal grandsire model considering GL in heifers as correlated, but a different trait to adult cows and animal repeatability model. The key objective of this study was to assess if selective mating of bulls with short GL estimated breeding values (EBV) can help to modify calving patterns in predominantly pasture-based production systems and thereby contribute to the reduction of calving induction.

Effects of source on bioavailability of selenium, antioxidant status, and performance in lactating dairy cows during oxidative stress-inducing conditions

Journal of Dairy Science -

In the current study, we used heat stress (HS) as an oxidative stress model to examine the effects of hydroxy-selenomethionine (HMSeBA), an organic selenium source, on selenium's bioavailability, antioxidant status, and performance when fed to dairy cows. Eight mid-lactation Holstein dairy cows (141 ± 27 d in milk, 35.3 ± 2.8 kg of milk/d, parity 2 or 3) were individually housed in environmental chambers and randomly assigned to 1 of 2 treatments: inorganic Se supplementation (sodium selenite; SS; 0.3 mg of Se/kg of dry matter; n = 4) or HMSeBA supplementation (0.3 mg of Se/kg of dry matter; n = 4).

Cooling cows with sprinklers: Effects of soaker flow rate and timing on behavioral and physiological responses to heat load and production

Journal of Dairy Science -

Spray strategies (e.g., flow rate and spray timing) may affect the surrounding microclimate and how cows use soakers, affecting cooling efficiency. Our objective was to evaluate the combined effects of spray timing (i.e., frequency, low: 3 min on, 6 min off; or high: 1.5 min on, 3 min off) and flow rates (3.3 or 4.9 L/min) on behavioral and physiological responses to heat load and production in Holstein cows managed in a freestall barn. In a 2 × 2 Latin square design, 3 cohorts of 4 pairs of cows averaging (±standard deviation) 36.7 ± 5.4 kg/d of milk were tested for 3 d/treatment.

Acute-phase inter-alpha-trypsin inhibitor heavy chain 4 levels in serum and milk of cows with subclinical mastitis caused by Streptococcus species and coagulase-negative Staphylococcus species

Journal of Dairy Science -

The aim of the study was to investigate the concentrations of acute-phase inter-α-trypsin inhibitor heavy chain 4 (ITIH4) in serum and milk of cows with subclinical mastitis caused by Streptococcus sp. (STR) and coagulase-negative Staphylococcus sp. (CNS) and healthy cows. The blood and milk samples were obtained from 60 mid-lactation, multiparous Holstein-Friesian cows from 7 herds in the Lublin region of Poland. In the milk samples from 40 cows with subclinical mastitis, Streptococcus sp. and CNS were isolated.

Antigenicity of β-lactoglobulin reduced by combining with oleic acid during dynamic high-pressure microfluidization: Multi-spectroscopy and molecule dynamics simulation analysis

Journal of Dairy Science -

Some food components can modulate the antigenicity of β-lactoglobulin (β-LG). This study investigated the role of oleic acid (OA) in reducing the antigenicity of β-LG. The results indicate the antigenicity of β-LG gradually decreased from 15 (sample with no OA) to 9.86, 7.51, and 6.01 µg/mL when interacting with OA during dynamic high-pressure microfluidization treatment at 0.1, 80, and 160 MPa. Although binding sites (n) of β-LG combined with OA at 0.1, 80, and 160 MPa decreased from 0.79 to 0.5 and 0.66, β-LG had a higher binding affinity (Ka) to OA than that of untreated β-LG.

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