Dairy Diets Research Articles

Effects of Yucca schidigera Based Feed Additive on In Vitro Dry Matter Digestibility, Efficiency of Microbial Production, and Greenhouse Gas Emissions of Four Dairy Diets

The present study evaluated the effects of a feed additive (synthesized from Yucca schidigera) on some fermentation variables. In the first of two experiments, seven concentrations of the feed additive were evaluated using the in vitro batch culture technique to determine the optimum dose to use in the second experiment. The substrates used were a total mixed ration (TMR) and alfalfa hay. The levels of inclusion were 0 (control), 0.5, 1, 2, 4, 6, and 8 g/head/d. After this initial evaluation, 2 g/head/d was selected for the second experiment. For the second study, four dietary substrates (two corn silages and two TMR; collected from different dairy farms in the Piedmont, North Carolina, area) were used. Incubation times were 3, 6, and 24 h and treatments were 0 (control) and 2 g/head/d of the feed additive. Inclusion of the feed additive did not affect (p > 0.05) in vitro dry matter disappearance. Additionally, the feed additive had no effect (p > 0.05) on short-chain fatty acid concentrations, microbial mass, and efficiency of microbial production. Methane production was reduced by 22.7% with feed additive inclusion. Similarly, lower (p = 0.013; 18%) carbon dioxide concentration was observed in the feed additive treatment. Ammonia and hydrogen sulfite concentrations were similar (p > 0.05) for both treatments. Inclusion of the feed additive at 2 g/head/d decreased methane and carbon dioxide concentrations in most of the diets. The energy saved by reducing the amount of methane produced was not partitioned into valuable products such as short-chain fatty acids and microbial mass.

Spontaneous Pregnancies in Polycystic Ovary Syndrome (PCOS) Patients with a Low Starch/Low Dairy Diet: A Retrospective Case Series

A low starch/low dairy diet resulted in spontaneous conceptions in ten obese infertile women with Polycystic Ovary Syndrome (PCOS). <strong>Case Report:</strong> Through a retrospective chart review of a fertility clinic

Effects of sucrose and lactose as partial replacement to corn in lactating dairy cow diets: a review.

Carbohydrates are one of the three macronutrients that provides energy in diets and are classified by their structures. Starch is a nonstructural carbohydrate and polysaccharide made of glucose monomers used for storage in plant cells. When starch makes up greater than 30% of the DM in diets there can be adverse effects on NDF digestibility due to decreases in ruminal pH. Sugars are water soluble carbohydrates that consist of monosaccharide and disaccharide units. Sugars ferment faster than starch because microorganisms in the rumen can ferment carbohydrates at different rates depending on their structure; however, this has not been shown to have negative effects on the ruminal pH. Sources of sugars such as molasses (sucrose) or whey (lactose) can be included in the diet as a partial replacement for starch in dairy cow diets. The purpose of replacing starch with sugars in a diet would be to add differing sources of carbohydrates in the diet to allow for continual fermentation of carbohydrates by the microorganisms in the rumen. It has been seen in studies and previous literature that the partial replacement of starch with sugars has the potential to maintain the ruminal environment and milk yield and composition in dairy cows without reducing NDF digestibility. The objective of this review is to evaluate the effects of partially replacing starch with sugars in dairy diets and its implication on ruminal fermentation, nutrient utilization, milk production, and feeding replacement strategy.

The impact of low-fat and full-fat dairy foods on symptoms of gastroesophageal reflux disease: an exploratory analysis based on a randomized controlled trial.

Gastroesophageal reflux disease (GERD) is a widely prevalent condition. High consumption of dairy foods and dietary fat are associated with worse GERD symptoms. However, existing data are inconsistent and mostly based on observational studies. The purpose of this exploratory analysis of a randomized controlled trial was to investigate the impact of low-fat and full-fat dairy food consumption on GERD symptoms. Seventy-two participants with metabolic syndrome completed a 4-week wash-in diet during which dairy intake was limited to three servings of nonfat milk per week. Participants were then randomized to either continue the limited dairy diet or switch to a diet containing 3.3 servings per day of either low-fat or full-fat milk, yogurt and cheese for 12weeks. Here, we report intervention effects on the frequency of acid reflux, and the frequency and severity of heartburn, exploratory endpoints assessed by a questionnaire administered before and after the 12-week intervention. In the per-protocol analysis (n = 63), there was no differential intervention effect on a cumulative heartburn score (p = 0.443 for the time by diet interaction in the overall repeated measures analysis of variance). Similarly, the intervention groups did not differentially affect the odds of experiencing acid regurgitation (p = 0.651). The intent-to-treat analyses (n = 72) yielded similar results. Our exploratory analyses suggest that, in men and women with the metabolic syndrome, increasing the consumption of either low-fat or full-fat dairy foods to at least three servings per day does not affect common symptoms of GERD, heartburn and acid regurgitation compared to a diet limited in dairy. ClinicalTrials.gov Identifier: NCT02663544, registered on January 26, 2016.

Effect of fat-reformulated dairy food consumption on postprandial flow-mediated dilatation and cardiometabolic risk biomarkers compared with conventional dairy: a randomized controlled trial

ABSTRACTBackgroundLonger-term consumption of SFA-reduced, MUFA-enriched dairy products has been reported to improve fasting flow-mediated dilatation (FMD). Yet, their impact on endothelial function in the postprandial state warrants investigation.ObjectivesThe aim was to compare the impact of a fatty acid (FA) modified with a conventional (control) dairy diet on the postprandial %FMD (primary outcome) and systemic cardiometabolic responses to representative meals, and retrospectively explore whether treatment effects differ by apolipoprotein E (APOE) or endothelial NO synthase (eNOS) Glu298Asp gene polymorphisms.MethodsIn a crossover-design randomized controlled study, 52 adults with moderate cardiovascular disease risk consumed dairy products [38% of total energy intake (%TE) from fat: FA-modified (target: 16%TE SFAs; 14%TE MUFAs) or control (19%TE SFAs; 11%TE MUFAs)] for 12 wk, separated by an 8-wk washout. Blood sampling and FMD measurements (0–480 min) were performed pre- and postintervention after sequential mixed meals that were representative of the assigned dairy diets (0 min, ∼50 g fat; 330 min, ∼30 g fat).ResultsRelative to preintervention (∆), the FA-modified dairy diet and meals (treatment) attenuated the increase in the incremental AUC (iAUC), but not AUC, for the %FMD response observed with the conventional treatment (–135 ± 69% vs. +199 ± 82% × min; P = 0.005). The ∆ iAUC, but not AUC, for the apoB response decreased after the FA-modified treatment yet increased after the conventional treatment (–4 ± 3 vs. +3 ± 3 mg/mL × min; P = 0.004). The ∆ iAUC decreased for plasma total SFAs (P = 0.003) and trans 18:1 (P < 0.0001) and increased for cis-MUFAs (P < 0.0001) following the conventional relative to the FA-modified treatment. No treatment × APOE or eNOS genotype interactions were evident for any outcome.ConclusionsThis study provides novel insights into the longer-term effects of FA-modified dairy food consumption on postprandial cardiometabolic responses.

Brain lipidomics and neurodevelopmental outcomes in intrauterine growth restricted piglets fed dairy or vegetable fat diets

Breast milk has neurodevelopmental advantages compared to infant formula, especially in low-birth-weight infants, which may in part relate to the fat source. This study compared neurodevelopmental outcomes in three-day-old normal birth weight (NBW) and intrauterine growth restricted (IUGR) piglets fed a formula diet with either vegetable oil (VEG) or bovine milk fat sources (MILK) for three weeks in a 2 × 2 factorial design. Behavioural tests, lipidomics, MRI and RNA sequencing analyses of plasma and brain tissue were conducted. The absolute levels of 82% and 11% of lipid molecules were different between dietary groups in plasma and hippocampus, respectively. Of the lipid molecules with differential abundance in the hippocampus, the majority were upregulated in MILK versus VEG, and they mainly belonged to the group of glycerophospholipids. Lower absolute brain weights, absolute grey and white matter volumes and behaviour and motor function scores, and higher relative total brain weights were present in IUGR compared to NBW with minor influence of diet. Cognitive function and cerebellar gene expression profiles were similar for dietary and weight groups, and overall only minor interactive effects between diet and birth weight were observed. Overall, we show that the dietary fat source influences the plasma and to a lesser degree the hippocampal lipidome and is unable to improve on IUGR-induced brain structural and functional impairments.

Multivariate modelling of milk fatty acid profile to discriminate the forages in dairy cows\u2019 ration

Although there are many studies on the importance of fatty acids (FA) in our diet and on the influence of dairy diets on FA metabolism, only a few investigate their predictive capacity to discriminate the type, amount and conservation method of farm forages. This research quantifies differences in milk FA concentrations and, using a supervised factorial discriminant analysis, assesses potential biomarkers when replacing maize with other silages, grass/lucerne hays or fresh grass. The statistical modelling identified three main clusters of milk FA profiles associated with silages, hays and fresh grass as dominant roughages. The main implication of a dairy cow feeding system based on poliphytic forages from permanent meadows is enhancing milk’s nutritional quality due to an increase in beneficial omega-3 polyunsaturated FA, conjugated linoleic acids and odd chain FA, compared to feeding maize silage. The study also identified a small but powerful and reliable pool of milk FA that can act as biomarkers to authenticate feeding systems: C16:1 c-9, C17:0, C18:0, C18:3 c-9, c-12, c-15, C18:1 c-9, C18:1 t-11 and C20:0.

Cortical and Subcortical Brain Volumes Partially Mediate the Association between Dietary Composition and Behavioral Disinhibition: A UK Biobank Study.

Behavioral disinhibition is observed to be an important characteristic of many neurodevelopmental and psychiatric disorders. Recent studies have linked dietary quality to levels of behavioral inhibition. However, it is currently unclear whether brain factors might mediate this. The current study investigates whether cortical and subcortical brain volumes mediate part of the association between dietary composition and behavioral disinhibition. A total of 15,258 subjects from the UK Biobank project were included in the current study. Dietary composition and behavioral disinhibition were based on Principle Component Analyses of self-reported dietary composition). As a further data reduction step, cortical and subcortical volume segmentations were input into an Independent Component Analysis. The resulting four components were used as mediator variables in the main mediation analyses, where behavioral disinhibition served as the outcome variable and dietary components as predictors. Our results show: (1) significant associations between all dietary components and brain volume components; (2) brain volumes are associated with behavioral disinhibition; (3) the mediation models show that part of the variance in behavioral disinhibition explained by dietary components (for healthy diet, restricted diet, and high-fat dairy diet) is mediated through the frontal-temporal/parietal brain volume component. These results are in part confirming our hypotheses and offer a first insight into the underlying mechanisms linking dietary composition, frontal-parietal brain volume, and behavioral disinhibition in the general adult population.

Exploring the pathways towards the mitigation of the environmental impacts of food consumption

Agriculture constitutes a quarter and more than a third of Denmark's global greenhouses gas (GHG) emissions and natural resource consumption, respectively. This paper aims to estimate the potential to lower Denmark's global food-related GHG, blue water and land footprints using the most recent version of a hybrid global multi-regional input-output (MRIO) database, EXIOBASE of the reference year, 2011. Specifically, we apply the ‘what if’ scenario-based MRIO approach to EXIOBASE and quantify the impact of increased livestock feed efficiency (FE), dietary changes, food loss and waste (FLW) reduction/prevention and food waste treatment scenarios on Denmark's global food-related GHG and resource footprints. We obtain modest reductions in Denmark's global food-related GHG, blue water and cropland footprint from the combination of livestock FE improvements and FLW reduction; 61 kt CO2e, 2 Mm3 and 30 kha, respectively. In contrast, dietary change towards no/less meat and dairy diets embodies the most significant reductions potential for Denmark's total global food-related GHG, blue water, croplands and grassland footprint by up to 34% (3.63 Mt. CO2e), 8% (90 Mm3), 23% (371 kha) and 78% (386 kha) respectively. A key policy priority should therefore be the nudging of Danish consumers towards sustainable diets. Also, this study's findings emphasise that FLW prevention remains the most effective food waste-related climate mitigation and resource efficiency strategy despite the benefits of food waste valorisation.

Comparative study of gut microbiota Mongolian and Asian people

Mongolia has the unique dietary habit having a great deal of animal products especially among rural resident.To capture the status of Mongolian gut microbiome, we characterized bacterial community of 98 healthy Mongolian adults and compared with that of adults in five Asian countries, including Korea, China, Japan, Thailand and Indonesia. Principal component analysis (PCA) was performed based on genus composition of each sample. As a result, three microbiome-type cluster, the so-called “enterotype”, driven by the three taxonomic groups, Prevotella (P-type), Bacteroides and Bifidobacterium (BB-type), and Ruminococcaceae (R-type), were observed. Most of Mongolian subjects harbored P-type, which is known to strongly depend on carbohydrate-based diets. Further, the metagenomic analysis indicated that Catenibacterium and Lactobacillus were enriched in Mongolian subjects which may be concerned with intake of animal-based and dairy products-based diets, respectively. These results suggest that gut microbiome status of Mongolian people associates with the traditional unique dietary habit.

Consumer Determinants of Purchasing Decisions on the Dairy Products Market

Purpose: The aim of this study was to try to define the basics and various factors that determine the purchasing behavior of consumers on the modern milk and milk products market. Design/Methodology/Approach: The study used the results of the author's empirical research in which 464 respondents were selected for the study in a purposeful manner. The main selection criterion was the respondents' declaration of regular purchase and consumption of dairy products in households. The research tool was a standardized questionnaire, which consisted of closed questions, both single and multiple choice, and it was fully anonymous. The obtained results allowed to draw conclusions and compare them with the general market trends taking place in the analyzed sector as well as with the results of research published by other authors dealing with related issues. Findings: The obtained results show that most of the purchasing decisions of dairy consumers are routine decisions. The main reason for consuming dairy products is the fact that they are suitable for direct consumption without their prior preparation, as well as the fact that the respondents have long become accustomed to the dairy diet in their households. In the hierarchy of factors determining the purchase of dairy products, the most important were sensory and functional impressions and the use-by date, but also various marketing stimuli are an important element. Practical Implications: The article contains information as well as guidelines for producers of dairy products, both for production and marketing. Thanks to the conducted research, the main directions of changes in the interests of buyers following contemporary consumer trends on the global market, which will become increasingly important in the future, have been shown. Originality / Value: The study contains significant findings regarding the variables affecting the direction of future consumption of dairy products on the market.

Impact of low-fat and full-fat dairy foods on fasting lipid profile and blood pressure: exploratory endpoints of a randomized controlled trial

Dietary guidelines traditionally recommend low-fat dairy because dairy's high saturated fat content is thought to promote cardiovascular disease (CVD). However, emerging evidence indicates that dairy fat may not negatively impact CVD risk factors when consumed in foods with a complex matrix. The aim was to compare the effects of diets limited in dairy or rich in either low-fat or full-fat dairy on CVD risk factors. In this randomized controlled trial, 72 participants with metabolic syndrome completed a 4-wk run-in period, limiting their dairy intake to ≤3 servings/wk of nonfat milk. Participants were then randomly assigned to 1 of 3 diets, either continuing the limited-dairy diet or switching to a diet containing 3.3 servings/d of either low-fat or full-fat milk, yogurt, and cheese for 12 wk. Exploratory outcome measures included changes in the fasting lipid profile and blood pressure. In the per-protocol analysis (n=66), there was no intervention effect on fasting serum total, LDL, and HDL cholesterol; triglycerides; free fatty acids; or cholesterol content in 38 isolated plasma lipoprotein fractions (P>0.1 for all variables in repeated-measures ANOVA). There was also no intervention effect on diastolic blood pressure, but a significant intervention effect for systolic blood pressure (P=0.048), with a trend for a decrease in the low-fat dairy diet (-1.6±8.6 mm Hg) compared with the limited-dairy diet (+2.5±8.2 mm Hg) in post hoc testing. Intent-to-treat results were consistent for all endpoints, with the exception that systolic blood pressure became nonsignificant (P=0.08). In men and women with metabolic syndrome, a diet rich in full-fat dairy had no effects on fasting lipid profile or blood pressure compared with diets limited in dairy or rich in low-fat dairy. Therefore, dairy fat, when consumed as part of complex whole foods, does not adversely impact these classic CVD risk factors. This trial was registered at clinicaltrials.gov as NCT02663544.

Casomorphins and Gliadorphins Have Diverse Systemic Effects Spanning Gut, Brain and Internal Organs.

Food-derived opioid peptides include digestive products derived from cereal and dairy diets. If these opioid peptides breach the intestinal barrier, typically linked to permeability and constrained biosynthesis of dipeptidyl peptidase-4 (DPP4), they can attach to opioid receptors. The widespread presence of opioid receptors spanning gut, brain, and internal organs is fundamental to the diverse and systemic effects of food-derived opioids, with effects being evidential across many health conditions. However, manifestation delays following low-intensity long-term exposure create major challenges for clinical trials. Accordingly, it has been easiest to demonstrate causal relationships in digestion-based research where some impacts occur rapidly. Within this environment, the role of the microbiome is evidential but challenging to further elucidate, with microbiome effects ranging across gut-condition indicators and modulators, and potentially as systemic causal factors. Elucidation requires a systemic framework that acknowledges that public-health effects of food-derived opioids are complex with varying genetic susceptibility and confounding factors, together with system-wide interactions and feedbacks. The specific role of the microbiome within this puzzle remains a medical frontier. The easiest albeit challenging nutritional strategy to modify risk is reduced intake of foods containing embedded opioids. In future, constituent modification within specific foods to reduce embedded opioids may become feasible.

Integrating needs-supportive delivery into a laboratory-based randomised controlled trial for adolescent girls with overweight and obesity: Theoretical underpinning and 12-week psychological outcomes

ABSTRACT When designing efficacy trials, researchers have a responsibility to “do no harm” and to “do good”. Given the psychological vulnerability of adolescent girls with overweight and obesity, it is important to consider the implications of participating in weight-related research studies. We investigated psychological outcomes from a 12-week laboratory-based randomised controlled trial aimed at improving body composition and bone health in adolescent girls with overweight and obesity. Sixty-three participants were randomised to three groups (Recommended dairy diet plus exercise (RDa, n = 24); Low dairy diet plus exercise (LDa, n = 25); no-intervention control (n = 14)). Self-Determination Theory-informed strategies were applied in both intervention groups to foster motivation and enhance psychological wellbeing. Motivation, perceived competence and self-perceptions were measured at 0 and 12 weeks. Fifty-four participants (24 RDa, 23 LDa, 7 Control) provided complete psychological data. There were no between group differences in 0- to 12-week change in motivation, perceived competence or global self-worth. Both intervention groups showed significant improvements in physical self-worth (p = 0.001), body satisfaction (p = 0.002) and perceived physical conditioning (p = 0.002), compared with the control group. A theory-informed, laboratory-based diet and exercise intervention produced favourable psychological outcomes for adolescent girls with overweight and obesity.

Alternative and Unconventional Feeds in Dairy Diets and Their Effect on Fatty Acid Profile and Health Properties of Milk Fat.

Simple SummaryMilk fat is an important compound in human nutrition. From a nutritional point of view, the production of milk with a higher content of polyunsaturated fatty acids, especially of those from the n3 group, is desirable because consumption of a diet with a lower n6/n3 ratio is considered to be beneficial for humans. The most effective way to achieve this goal is via dietary manipulations in ruminants. In addition to the feedstuffs commonly used in dairy animal nutrition, there are some alternative or unconventional feedstuffs that are often used for other purposes, e.g., for the reduction of methane production in the rumen. However, such feedstuffs can also alter the fatty acid profile of milk, and thus they can have an impact on the health properties of milk fat.Milk fat is an important nutritional compound in the human diet. From the health point of view, some fatty acids (FAs), particularly long-chain PUFAs such as EPA and DHA, have been at the forefront of interest due to their antibacterial, antiviral, anti-inflammatory, and anti-tumor properties, which play a positive role in the prevention of cardiovascular diseases (CVD), as well as linoleic and γ-linolenic acids, which play an important role in CVD treatment as essential components of phospholipids in the mitochondria of cell membranes. Thus, the modification of the FA profile—especially an increase in the concentration of polyunsaturated FAs and n-3 FAs in bovine milk fat—is desirable. The most effective way to achieve this goal is via dietary manipulations. The effects of various strategies in dairy nutrition have been thoroughly investigated; however, there are some alternative or unconventional feedstuffs that are often used for purposes other than basic feeding or modifying the fatty acid profiles of milk, such as tanniferous plants, herbs and spices, and algae. The use of these foods in dairy diets and their effects on milk fatty acid profile are reviewed in this article. The contents of selected individual FAs (atherogenic, rumenic, linoleic, α-linolenic, eicosapentaenoic, and docosahexaenoic acids) and their combinations; the contents of n3 and n6 FAs; n6/n3 ratios; and atherogenic, health-promoting and S/P indices were used as criteria for assessing the effect of these feeds on the health properties of milk fat.

Effects of feeding a live yeast on rumen fermentation and fiber degradability of tropical and subtropical forages.

The effect of live yeast Saccharomyces cerevisiae strain CNCM I-1077 (SC) on the ruminal degradability of different forages commonly found in dairy diets in South America was evaluated. We also assessed if SC supplementation interacts with forage group to affect ruminal fiber degradability. Four non-lactating rumen-cannulated Holstein cows were randomly assigned to two treatment sequences: Control-SC-Control or SC-Control-SC, in a switchback design, with three 30-day periods. Cows in the SC treatment were supplied with 1 × 1010 colony-forming units of yeast daily via rumen cannula. In situ degradability of dry matter (DM) and neutral detergent fiber (aNDF) was measured in 15 forages collected in South America. Forages were assigned to one of three groups: corn silages; tropical grasses (sugarcane silages and tropical grass silages); and temperate grasses and alfalfa (oat silages, ryegrass silages, alfalfa silage, and alfalfa hay). Cows supplemented with SC had higher (P=0.05) counts of yeasts and lower (P=0.03) concentration of lactate in rumen fluid. There was no interaction between forage group and yeast supplementation (P > 0.10) on in situ degradability. The SC increased DM (by 4.6%) and aNDF degradation (by 10.3%) at 24 h of incubation (P < 0.05). Metabolomics revealed that a chemical entity (C17 H29 N6 O3 , m/z 365.2284 [M + H]+ ) from the family of lipids and related molecules was suppressed in the rumen fluid of cows supplemented with SC. The SC supplementation improved DM and aNDF degradability regardless of the forage group. © 2021 Society of Chemical Industry.

The impact of diets rich in low-fat or\\ full-fat dairy on glucose tolerance and its determinants: a randomized controlled trial

Dairy foods, particularly yogurt, and plasma biomarkers of dairy fat intake are consistently inversely associated with incident type 2 diabetes. Yet, few trials assessing the impact of dairy on glucose homeostasis include fermented or full-fat dairy foods. We aimed to compare the effects of diets rich in low-fat or full-fat milk, yogurt, and cheese on glucose tolerance and its determinants, with those of a limited dairy diet. In this parallel-design randomized controlled trial, 72 participants with metabolic syndrome completed a 4-wk wash-in period, limiting dairy intake to ≤3 servings/wk of nonfat milk. Participants were then randomly assigned to either continue the limited dairy diet, or switch to a diet containing 3.3 servings/d of either low-fat or full-fat dairy for 12 wk. Outcome measures included glucose tolerance (area under the curve glucose during an oral-glucose-tolerance test), insulin sensitivity, pancreatic β-cell function, systemic inflammation, liver-fat content, and body weight and composition. In the per-protocol analysis (n=67), we observed no intervention effect on glucose tolerance (P=0.340). Both the low-fat and full-fat dairy diets decreased the Matsuda insulin sensitivity index (ISI) (means±SDs -0.47±1.07 and -0.25±0.91, respectively) and as compared with the limited dairy group (0.00±0.92) (P=0.012 overall). Body weight also changed differentially (P=0.006 overall), increasing on full-fat dairy (+1.0 kg; -0.2, 1.8 kg) compared with the limited dairy diet (-0.4 kg; -2.5, 0.7 kg), whereas the low-fat dairy diet (+0.3 kg; -1.1, 1.9 kg) was not significantly different from the other interventions. Intervention effects on the Matsuda ISI remained after adjusting for changes in adiposity. No intervention effects were detected for liver fat content or systemic inflammation. Findings in intent-to-treat analyses (n=72) were consistent. Contrary to our hypothesis, neither dairy diet improved glucose tolerance in individuals with metabolic syndrome. Both dairy diets decreased insulin sensitivity through mechanisms largely unrelated to changes in key determinants of insulin sensitivity.This trial was registered at clinicaltrials.gov as NCT02663544.

English

Aflatoxins (AF) are potent mycotoxins with carcinogenic, teratogenic, and mutagenic potential. There is no agreement on the safe AF maximum residue levels established in different countries (5.0 to &gt;20.0 μg/kg) to avoid feed toxicity in dairy cows and to protect the food chain. The objective was to establish a diagnosis of subclinical aflatoxicosis via changes in biochemical values during long-term exposure of AF low concentrations under field conditions. A cohort of 90 Holstein heifers were selected (395±10 kg/BW; 14-15 months) in a large dairy farm in the central Mexico highlands. Monthly samples of blood serum, feedstuffs, total mixed ration, and raw milk were obtained (26 months) and analyzed via spectrophotometric and HPLC methods. Dairy diets were naturally contaminated with AF (8.1±5.2 µg/kg). No cow showed clinical disease, but significant changes in biochemistry values were associated to AF intake at levels &gt;5.0 µg/kg, especially a serum concentrations decrease in albumin, total protein and reduced glutathione; furthermore, an increase in prothrombin time, and in specific activity of AF metabolizing enzymes (glutathione S-transferase, γ-glutamyl transferase, alanine aminotransferase, aspartate aminotransferase, and alkaline phosphatase). Raw milk samples were naturally contaminated with AF in milk (AFM1; 43.1±24.0 ng/kg). A linear dose-response relationship between AF in feed and AFM1 concentrations was observed (AFM1=19.2+2.70(AF); P&lt;0.01; R2 :62.1%). Moreover, reproductive failure and inter-pregnancy interval rates of cows exposed to higher AF concentrations (&gt;10.0 µg/kg) were increased. These results suggested that in the long term, low amounts of AF exposure may lead to significant adverse effects consistent with subclinical aflatoxicosis.

Meta-analysis and sustainability of feeding slow-release urea in dairy production.

Slow-release urea (SRU) is a coated non-protein nitrogen (NPN) source for providing rumen degradable protein in ruminant nutrition. A meta-analysis was conducted to evaluate the effects of replacing vegetable protein sources with SRU (Optigen®, Alltech Inc., USA) on the production performance of dairy cows. Additionally, the impact of SRU supplementation on dairy sustainability was examined by quantifying the carbon footprint (CFP) of feed use for milk production and manure nitrogen (N) excretion of dairy cows. Data on diet composition and performance variables were extracted from 17 experiments with 44 dietary comparisons (control vs. SRU). A linear mixed model and linear regression were applied to statistically analyse the effect of SRU on feed intake and production performance. Feeding SRU decreased (P < 0.05) dry matter intake (DMI, -500 g/d) and N intake (NI, -20 g/d). There was no significant effect (P > 0.05) on milk yield, fat-corrected milk, energy-corrected milk, and milk fat and protein composition. However, SRU supplementation improved (P < 0.05) feed efficiency (+3%) and N use efficiency (NUE, +4%). Regression analyses revealed that increasing SRU inclusion level decreased DMI and NI whereas increasing dietary crude protein (CP) increased both parameters. However, milk yield and feed efficiency increased in response to increasing levels of SRU inclusion and dietary CP. The NUE had a positive relationship with SRU level whereas NUE decreased with increasing dietary CP. The inclusion of SRU in dairy diets reduced the CFP of feed use for milk production (-14.5%; 373.13 vs. 319.15 g CO2 equivalent/kg milk). Moreover, feeding SRU decreased manure N excretion by 2.7% to 3.1% (-12 to -13 g/cow/d) and N excretion intensity by 3.6% to 4.0% (-0.50 to -0.53 g N/kg milk). In conclusion, feeding SRU can contribute to sustainable dairy production through improvement in production efficiency and reduction in environmental impacts.

Basics of dairy diet design

The challenges of feeding dairy cows to maximize production while doing it in an economically sustainable way, requires dairy nutritionists and veterinarians to have a great understanding of rumen microbial output and the feeds we utilize to feed the rumen. It is the purpose of this presentation to describe and explain some very basic concepts of rumen dynamics and microbiology that are utilized to make decisions on how to include different feeds into diets while maintaining rumen and cow health and maximizing rumen output.