Immune-metabolic-inflammatory markers in Holstein cows exposed to a nutritional and environmental stressing challenge

Identification of Predictive Biomarkers of Lameness in Transition Dairy Cows

The aim of this study was to identify with a high level of confidence metabolites previously identified as predictors of lameness and understand their biological relevance by carrying out pathway analyses. For the dairy cattle sector, lameness is a major challenge with a large impact on animal welfare and farm economics. Understanding metabolic alterations during the transition period associated with lameness before the appearance of clinical signs may allow its early detection and risk prevention. The annotation with high confidence of metabolite predictors of lameness and the understanding of interactions between metabolism and immunity are crucial for a better understanding of this condition. Using liquid chromatography-tandem mass spectrometry (LC-MS/MS) with authentic standards to increase confidence in the putative annotations of metabolites previously determined as predictive for lameness in transition dairy cows, it was possible to identify cresol, valproic acid, and gluconolactone as L1, L2, and L1, respectively which are the highest levels of confidence in identification. The metabolite set enrichment analysis of biological pathways in which predictors of lameness are involved identified six significant pathways (p < 0.05). In comparison, over-representation analysis and topology analysis identified two significant pathways (p < 0.05). Overall, our LC-MS/MS analysis proved to be adequate to confidently identify metabolites in urine samples previously found to be predictive of lameness, and understand their potential biological relevance, despite the challenges of metabolite identification and pathway analysis when performing untargeted metabolomics. This approach shows potential as a reliable method to identify biomarkers that can be used in the future to predict the risk of lameness before calving. Validation with a larger cohort is required to assess the generalization of these findings.

Impact of Heat Stress on the Balance between Oxidative Markers and the Antioxidant Defence System in the Plasma of Mid-Lactating Modicana Dairy Cows

Animal health is affected during heat stress as a result of impaired immune responses, increased production of reactive oxygen species, and/or a deficiency of antioxidants. This leads to an imbalance between oxidants and antioxidants and results in oxidative stress. Heat stress is usually measured in dairy cattle via the temperature-humidity index (THI). In the present study, we aimed at assessing the influence of incremental THI on the balance between oxidative markers and the antioxidant defence system in the plasma of Modicana cows. Twenty-four multiparous, mid-lactating dairy cows were divided into two groups on the basis of different levels of mean THI reached in the period of the previous week up until the day of blood and milk sampling (April THI1:55, May THI2:68, June THI3:71, July THI4:80). The blood samples were collected to measure reactive oxygen metabolites (ROM) and antioxidant defense markers (ferric reducing ability of plasma (FRAP), paraoxonase (PON), advanced oxidation protein products (AOPP), plasma thiol groups (SHp), as well as lipid-soluble antioxidant pro-vitamin (β-carotene) and vitamins (tocopherol and retinol). Milk characteristics, haematological values, and plasma biochemical metabolites were also evaluated. Results showed a significant increase in ROM (p < 0.05) and a significant decrease in PON (p < 0.05), AOPP (p < 0.05), and β-carotene (p < 0.001). Incremental THI significantly decreased levels of milk fat content, red and white blood cells, plasma glucose, and non-esterified fatty acids, while significantly increasing monocytes and the concentrations of β-hydroxybutyrate and creatinine, but not fructosamine. The results of the study show that heat stress significantly affects reactive oxygen species production and antioxidant parameters. Carotenoid supplementation should be considered to alleviate the impact of these effects.

Polish Dairy Farm Transformations and Competitiveness 20 Years after Poland's Accession to the European Union

Poland is one of the leading milk producers in the EU, being the fifth largest after countries such as Germany, France, Italy, and the Netherlands. From Poland's accession to the European Union in 2004 up to 2022, Polish milk production experienced dynamic development. In this, there occurred a strong decline in the number of dairy farms (by -78%) and the number of cows (by -21%), an increase in dairy herd size (3.5 times) and increase in milk production (+60%) and milk yield per cow (by +62%). These were among the highest growth dynamics among the analysed countries. As a result of this significant transformation, Poland maintained an important position in milk exports, with a 31% export share in production in 2022. The scale of milk production was the basic factor determining the efficiency and competitiveness of dairy farms in Poland. Milk yield, farmland productivity, labour productivity, milk price, and the Corrected Competitiveness Index (based on labour and land opportunity costs) all showed a positive relationship with cow herd size on the farm. Milk production is highly uncompetitive for smaller farms (<15 cows). Despite substantial public support, the smaller farms, where subsidies equal up to 47% of total production value, could not earn sufficient income to cover the cost of capital, risk, and management in 2008, and even more so in 2021. This is because the farm income is too small to cover the extremely high opportunity cost of labour. The larger farms (with 30 cows and more) are competitive and responsible for the majority (~60-70%) of milk produced and delivered to the market. The most challenging from the sectoral policy point of view are medium farms (10-29 cows), whose share in production and deliveries is still important. To survive as economically viable units, these farms have to increase in scale and improve productivity. Otherwise, they will be gradually supplanted by larger farms.

Monitoring Cattle Ruminating Behavior Based on an Improved Keypoint Detection Model

Cattle rumination behavior is strongly correlated with its health. Current methods often rely on manual observation or wearable devices to monitor ruminating behavior. However, the manual monitoring of cattle rumination is labor-intensive, and wearable devices often harm animals. Therefore, this study proposes a non-contact method for monitoring cattle rumination behavior, utilizing an improved YOLOv8-pose keypoint detection algorithm combined with multi-condition threshold peak detection to automatically identify chewing counts. First, we tracked and recorded the cattle's rumination behavior to build a dataset. Next, we used the improved model to capture keypoint information on the cattle. By constructing the rumination motion curve from the keypoint information and applying multi-condition threshold peak detection, we counted the chewing instances. Finally, we designed a comprehensive cattle rumination detection framework to track various rumination indicators, including chewing counts, rumination duration, and chewing frequency. In keypoint detection, our modified YOLOv8-pose achieved a 96% mAP, an improvement of 2.8%, with precision and recall increasing by 4.5% and 4.2%, enabling the more accurate capture of keypoint information. For rumination analysis, we tested ten video clips and compared the results with actual data. The experimental results showed an average chewing count error of 5.6% and a standard error of 2.23%, verifying the feasibility and effectiveness of using keypoint detection technology to analyze cattle rumination behavior. These physiological indicators of rumination behavior allow for the quicker detection of abnormalities in cattle's rumination activities, helping managers make informed decisions. Ultimately, the proposed method not only accurately monitors cattle rumination behavior but also provides technical support for precision management in animal husbandry, promoting the development of modern livestock farming.

Changes on the rumen microbial community composition in dairy cows subjected to an acidogenic diet

In modern breeding systems, cows are subjected to many stress factors. Animals fed with a high-grain diet may have a decreased rumen pH, which would lead to subacute ruminal acidosis syndrome. The aim of this study was to investigate the evolution of microbial community composition in cows undergoing a dietary stress challenge. Twelve cows were subjected to a challenge period consisted in a rapid change of ration, from a normal (45.4:54.6 forage: concentrate) to a high-grain content diet (24.8:75.2 forage: concentrate) to induce sub-acute ruminal acidosis. Individual rumen fluid content samples were collected before (T0), and during the challenge (T3, T14, T28). DNA from rumen contents was extracted, purified, and sequenced to evaluate Bacterial populations and sequencing was performed on Illumina MiSeq. The effect of animal conditions on rumen microbial community was quantified through a linear mixed model. The acidogenic diet created 2 main clusters: ruminal hypomotility (RH) and milk fat depression (MFD). The microbial composition did not differ in T0 between the 2 groups, while during the challenge Ruminococcus spp., Treponema spp., Methanobrevibacter spp., and Methanosphaera spp. concentrations increased in RH cows; Succinivibrio spp. and Butyrivibrio spp. concentrations increased in MFD cows. Prevotella spp. and Ruminococcus spp., were negatively correlated, while Christenellaceae family were positively correlated with both Methanobrevibacter spp. and Methanosphaera spp. Moreover, the same diet affected differently cows' microbiota composition, underlying the impact of the host effect. Other studies are necessary to deepen the relationship between microbiota composition and host.

Finding biomarkers of experience in animals

At a time when there is a growing public interest in animal welfare, it is critical to have objective means to assess the way that an animal experiences a situation. Objectivity is critical to ensure appropriate animal welfare outcomes. Existing behavioural, physiological, and neurobiological indicators that are used to assess animal welfare can verify the absence of extremely negative outcomes. But welfare is more than an absence of negative outcomes and an appropriate indicator should reflect the full spectrum of experience of an animal, from negative to positive. In this review, we draw from the knowledge of human biomedical science to propose a list of candidate biological markers (biomarkers) that should reflect the experiential state of non-human animals. The proposed biomarkers can be classified on their main function as endocrine, oxidative stress, non-coding molecular, and thermobiological markers. We also discuss practical challenges that must be addressed before any of these biomarkers can become useful to assess the experience of an animal in real-life.

Parity and nutrient total-tract digestibility in dairy cows during transition period

Cows experience many physiological, nutritional and social changes during transition period. This study aims to evaluate the differences in nutrients total-tract digestibility (nTTD) between primiparous (PP) and multiparous (MP) cows through the transition period. From -23, -5, 0, 7, 14, and 30 days from calving a sample of feed and feces samples were collected from 25 Holstein cows (11 PP and 14 MP) as well as daily rumination time through accelerometers. The results show that average nTTD were different (p ≤ 0.02) for amylase-treated neutral detergent fiber organic matter (aNDFom) and potentially digestible neutral detergent fiber (pdNDF240; 52.5 vs. 54.0 and 78.8 vs. 81.3, respectively in PP vs. MP), while no differences were found regarding pdNDF24 and starch (88.5 vs. 88.6 and 95.1 vs. 96.1, respectively in PP vs. MP). Total-tract starch digestibility (TTstarchD) was different among timepoints (p < 0.01), going from an average of 91.40 up to 97.39% of starch, on times -23 and 14, respectively. Differences in total-tract digestibility of aNDFom among timepoints (p < 0.01) was expected because of differences in diet composition among lactating and non-lactating cows. No differences in daily rumination time (p = 0.92), TTstarchD and total-tract potentially digestible NDF digestibility at 24 h (TTpdNDF24D) were recorded. Our findings show that fiber digestibility during the transition period is higher in MP probably for a different ruminal retention time. These differences should be considered when formulating rations for groups with different parity number.

Effects of herbal supplements on milk production quality and specific blood parameters in heat-stressed early lactating cows

The present study explored the influence of supplemental herbal mixtures on cow milk production, quality, and blood parameters in dairy cows under high ambient temperatures. Thirty Holstein cows were randomly assigned into three experimental groups of 10 each. The first control group was supplied with the commercial basal diet, whereas two treatment groups were provided with the commercial basal diet supplemented with 50 and 100 g/head/day of the herbal mixture, respectively. The results showed that the mixture of herbal supplementation did not influence weekly milk production. Milk total fat, triglyceride, and total protein values were not affected (p < 0.05) in cows fed on basal diets supplemented with herbal mixture; however, milk cholesterol was decreased significantly by 100 mg/head/day of the herbal mixture. On the other hand, lactose has increased significantly by adding 100 mg/head/day of herbal mixture. Furthermore, the total cholesterol level in serum was decreased by adding 100 mg/head/day of the herbal mixture, while plasma prolactin, cortisol, GOT, and GPT were unaffected. Regarding fatty acids (C18, C18:1 (c9), 18:1 (c11), 18:2 (c9, c12), 18:2 (t9, t12), and CLA (c9, t11)), there was no significant variation between the groups. Meanwhile, both C19:00 and 18:3 (c6, c9, and c12) were noticeably higher (p < 0.05) in the group that received 100gm, followed by 50 mg, compared to the control. In conclusion, the supplement with a herbal mixture positively affected milk quality by decreasing total cholesterol and increasing lactose, milk fatty acid profile by increasing unsaturated fatty acids content, and plasma cholesterol levels.

Feed Efficiency and Physiological Parameters of Holstein and Crossbred Holstein × Simmental Cows

This study aimed to compare the feed efficiency (FE) and physiological parameters of Holstein and crossbred Holstein × Simmental cows in a confinement system during winter and summer. The study was conducted in a dairy farm in southern Brazil by including a total of 48 multiparous cows. The cows were studied for 21 days in two periods, summer and winter, and their daily dry matter intake (DMI), milk yield (MY), rectal temperature (RT), respiratory rate (RR), body weight, and body condition score were recorded. An analysis of variance was conducted using the SAS statistical package. The results showed that crossbred Holstein × Simmental cows have a similar FE as Holstein cows in a high-production system (1.83 × 1.81 kg DMI/kg MY, respectively), and they can achieve the same production levels as purebred Holstein cows (43.8 vs. 44.5 milk/cow/day). Our findings indicated a difference for the period as both genetic groups achieved higher FE in winter than in summer (1.98 vs. 1.67 DMI/kg MY, respectively). In addition, we found evidence that crossbred cows are better at dissipating body heat during heat-stress situations, as they have higher RR in summer compared to purebred cows, while Holstein cows have higher RT in summer afternoons than crossbred cows. Therefore, using crossbred Holstein × Simmental cows is an alternative for high-production systems.

Dairy Cows Are Limited in Their Ability to Increase Glucose Availability for Immune Function during Disease

Shortages of energy and glucose have been hypothesized to play a key role in the development of and responses to production diseases in dairy cows during early lactation. Given the importance of glucose for immune functions, we used a recently established method for the estimation of glucose balance (GB) to evaluate glucose availability during disease phases. A dataset comprising ration analyses as well as individual daily milk yields (MY), dry matter intake (DMI), body weights, and health records of 417 lactations (298 cows) was used to calculate individual daily GB and energy balance (EB). The magnitude and dynamics of MY, DMI, GB, and EB were evaluated in the weeks before, at, and after diagnoses of inflammatory diseases in different stages of early lactation from week in milk 1 to 15. Diagnoses were categorized as mastitis, claw and leg diseases, and other inflammatory diseases. Mixed linear models with a random intercept and slope term for each lactation were used to evaluate the effect of diagnosis on MY, DMI, GB, and EB while accounting for the background effects of week in milk, parity, season, and year. When unaffected by disease, in general, the GB of cows was close to zero in the first weeks of lactation and increased as lactation progressed. Weekly means of EB were negative throughout all lactation stages investigated. Disease decreased both the input of glucose precursors due to a reduced DMI as well as the output of glucose via milk due to a reduced MY. On average, the decrease in DMI was −1.5 (−1.9 to −1.1) kg and was proportionally higher than the decrease in MY, which averaged −1.0 (−1.4 to −0.6) kg. Mastitis reduced yield less than claw and leg disease or other diseases. On average, GB and EB were reduced by −3.8 (−5.6 to −2.1) mol C and −7.5 (−10.2 to −4.9) MJ in the week of diagnosis. This indicates the need to investigate strategies to increase the availability of glucogenic carbon for immune function during disease in dairy cows.

Evaluation of fecal sampling time points to estimate apparent nutrient digestibility in lactating Holstein dairy cows

Introduction

The aim of this study was the evaluation of nutrient excretion patterns in samples of feces collected every 2 h to define the best sampling protocol for estimation of apparent digestibility.

Methods

Four multiparous mid-lactation Holstein cows, housed in a tie stall barn and milked twice a day (0800; 1900 h), were enrolled. Dry total mixed ration (TMR) without silages was fed once (0800 h) per day. Feces were sampled every 2 h for 72 h. Each sample was divided in 3 portions: hourly sample sample (8, 10, 12, 14, 16, 18, 20, 22, 00, 2, 4, 6), 8-h composite sample (00-06, 08-14 and 16-22), and a 24-h composite sample. Complete chemical analyses were performed and total tract nutrient digestibility was calculated using undegraded neutral detergent fiber at 240 h of in vitro fermentation (uNDF240h) as a marker. Feeding and rumination patterns were also recorded during the trial.

Results and discussion

For some parameters, excretion was not constant throughout the day: neutral detergent fiber (aNDFom), undegraded neutral detergent fiber at 24 h of in vitro fermentation (uNDF24h), uDNF240h, total tract crude protein digestibility (TTCPD), total tract neutral detergent fiber digestibility (TTaNDFomD), total tract potentially degraded neutral detergent fiber at 240 h of in vitro fermentation digestibility (TTpdNDF240hD) with minimal values after new TMR delivery and maximal values 12 h after feed delivery. Feeding and ruminating behavior seemed to have an important role in the excretion pattern, due to the pushing and evacuating effect they have. Considering our results, two fecal samples at 12 and 24 h after the TMR delivery are suggested. For one daily sample, 12 h post time of most stable and constant rumination 0000-0600 h, which is also 8 h post feed delivery is suggested.

Performance, Feeding Behavior and Immune Response in Nellore and Angus × Nellore Steers Fed Whole Shelled Corn Diets with or without Fiber

Simple Summary

Grain diets provide a higher energy supply during the finishing phase, however, they can reduce rumen pH, leading to physiological stress in animals, affecting immune and metabolic systems and animal performance. To avoid this, an alternative is using fiber sources in low quantities. This study indicated that using fiber sources increases DMI and performance in whole shelled corn diets, and greater DMI increases haptoglobin blood concentration in low fiber diets.

Abstract

This study aimed to evaluate performance, to evaluate performance, carcass traits, feeding behavior, and humoral immune response in Nellore and Angus × Nellore steers fed whole shelled corn diets. Sixteen Nellore and 16 Angus × Nellore steers with 353 ± 25.3 kg were randomly assigned into 2 feeding groups, whole shelled corn without forage (WSC) or whole shelled corn and sugarcane bagasse (WSCB). The data were analyzed using the MIXED procedure of SAS (SAS Inst. Inc., Cary, NC, USA). Angus × Nellore steers had greater final BW, DMI, ADG, and subcutaneous fat thickness than Nellore. Moreover, Nellore steers had lower neutral detergent fiber (NDF) intake but spent more time ruminating and had a greater rumination rate of NDF. Regarding the diets, steers fed the WSCB had greater DMI and spent more time chewing and ruminating. Nellore × Angus steers had a greater haptoglobin concentration. The concentration of D-Lactate tended to be greater in the Nellore steers regardless of diet. In conclusion, the use of sugarcane bagasse in WSC diets increases DMI and ADG without affecting feed efficiency or the carcass traits of the steers. Although Angus × Nellore steers have increased haptoglobin concentration, this effect was not enough to reduce the performance of these animals.

Effects of Environmental Temperature and Humidity on Milk Composition, Microbial Load, and Somatic Cells in Milk of Holstein Dairy Cows in the Northeast Regions of Iran

The present study aims to examine the relationships between temperature and humidity and milk composition, microbial load, and somatic cells in the milk of Holstein dairy cows. For this purpose, the temperature−humidity index, ambient temperature, and relative humidity data were obtained from the nearest weather stations. Production data were obtained from four dairy farms in Golestan province, Iran, collected from 2016 to 2021. The traits investigated were protein, fat, solids-not-fat (SNF), microbial load, and somatic cell count (SCC) in milk. The effects of the environmental temperature, humidity, month, and season on the milk composition, microbial load, and somatic cells were analyzed through analysis of variance. The effects of environmental temperature, humidity, month, and season on the milk composition, microbial load, and somatic cell composition were analyzed using a mixed procedure with a restricted maximum likelihood model. Although our findings revealed that there were significant differences in fat, protein, SNF, and SCC among the different months of the year (p < 0.01), no significant difference was observed in the total microbial count in milk. Environmental temperature presented significant impacts on fat, protein, SNF, SCC, and total microbial count within various temperature ranges (p < 0.01). When the temperature increased from 6.2 °C to 31.3 °C, the milk protein, fat, SNF, and somatic cell count significantly decreased, by approximately 4.09%, 5.75%, 1.31%, and 16.8%, respectively; meanwhile, the microbial count in milk significantly increased, by approximately 13.7%. Humidity showed an influence on fat, protein, non-fat solids, somatic cells, and total microbial count within different temperature ranges (p < 0.01). When the humidity increased from 54% to 82%, the milk protein, fat, SNF, and SCC significantly increased, by approximately 3.61%, 4.84%, 1.06%, and 10.2%, respectively; meanwhile, the microbial count in milk significantly decreased, by approximately 16.3%. The results demonstrate that there is a negative correlation between different months of the year, temperature, and the humidity of the environment, in terms of milk components and SCC. Our findings demonstrate that the optimum performance, in terms of milk composition, occurred in the first quarter of the year. As temperature increases and humidity decreases, milk quality decreases. Therefore, the adverse effects of environmental conditions on agricultural profits are not negligible, and strategies to better deal with the negative environmental effects are needed in order to improve milk quality in dairy cows.

Effect of an Immunomodulatory Feed Additive in Mitigating the Stress Responses in Lactating Dairy Cows to a High Concentrate Diet Challenge

Simple Summary

Dairy cows are often exposed to stressors during the lactation cycle. Nutritional stressors could be caused by rich-grain diet, leading to ruminal pH reduction and subsequent systemic inflammation. This metabolic pathology impacts animal health and productivity. Feed additives could provide beneficial effects on innate immune function in dairy cows, especially during stressing periods. The goal of this study was to determine the effect of OmniGen-AF on measures of immunity, inflammation, and liver function in lactating dairy cows fed a high-starch, low-fiber diet. Changes in rumination, pH, and volatile fatty acids were recorded. Treated cows resulted in better rumen volatile fatty acids profile and also showed shifts in hematological parameters compatible with a prompter regeneration of red blood cells, greater proportion of neutrophils, lower levels on GGT, PON, and BHB. These results show evidence of the nutritional stress induced by feeding a high-starch, low-fiber diet, and suggest that the fed additive tested modulates some of the metabolic and immunological responses to sub-acute ruminal acidosis.

Abstract

Dairy cows are often exposed to multiple stressors in a lactation-cycle, with sub-acute ruminal acidosis (SARA) a frequent example of nutritional stress. SARA affects ruminal and intestinal equilibrium resulting in dysbiosis with localized and systemic inflammation impacting animal health and productivity. OmniGen-AF (OMN, Phibro Animal Health Corporation, Teaneck, NJ, USA) is a feed product recognized for modulating innate immune function, especially during periods of stress. The objective of this study was to determine the effects of OMN in lactating dairy cows fed a high-starch, low-fiber diet. Twenty-four blocked cows were assigned to control or treatment (55 g/d). After the additive adaptation (49 d) cows were fed the challenge diet (28 d). Milk, rumination and pH were continuously recorded; components, rumen fluid, and blood were taken in multiple time-point and analyzed. Results showed that the challenge decreased the rumination, shifted ruminal fluid composition, decreased milk production and the components, and slightly increased the time below pH 5.5, with no differences between groups. The treatment produced greater rumen butyrate and lower lactate, prompter regeneration of red blood cells, increase of neutrophils, lower paraoxonase, gamma-glutamyl-transferase, and β-hydroxybutyrate, with no differences on other tested inflammatory markers. Results show that OMN helps modulating some of the metabolic and immunological responses to SARA.

Effects of forage quantity and access-time restriction on feeding behaviour, feed efficiency, nutritional status, and dairy performance of dairy cows fed indoors

Optimising feed is a key challenge for dairy livestock systems, as forage stock shortages are increasingly frequent and feed is the biggest operating cost. The aim of this experiment was to evaluate the effects of reducing forage quantity and access time on dairy performance and animal nutritional status during indoor feeding. Twenty-seven Montbéliarde and Holstein cows were randomly allocated to three groups of nine cows balanced by breed, parity, days in milk, and milk yield. The three groups were given 3.9 kg DM/day of second-cut hay and 4.5 kg/day of concentrate and either i) ad libitum access to first-cut hay (Ad Libitum group; AL), ii) 10.5 kg/day of first-cut hay (Quantity-restricted group; QR), or iii) 10.5 kg/day of first-cut hay but with access time restricted to only 2 h in the morning and 2 h in the afternoon (Quantity-and-Time-restricted group; QTR). Milk yield, composition and coagulation properties, cow nutritional status (weight, body condition score, blood metabolites) and cow activities were recorded. The AL group ingested 10 % more feed than the QR group and 16 % more feed than the QTR group. Organic matter digestibility was lower in the AL group than in the QR and QTR groups whereas feed efficiency did not differ. Milk yield was not significantly different among the three groups. Compared to the QR and QTR groups, the AL group had significantly higher milk fat (35.9 vs 32.9 and 32.8 g/kg of milk) and milk protein content (29.5 vs 27.7 and 28.5 g/kg of milk). QR and QTR cows mobilised their body fat, resulting in a lower final body condition score, and tended to have a lower blood non-esterified fatty acid concentration than the AL group. QTR cows showed greater body fat mobilisation, but their final corrected BW was not different from AL cows. Access-time restriction did not impact fat and protein content but led to decreased casein, lactose contents and casein-to-whey protein ratio. The forage savings achieved through this feed management practice could prove economically substantial when forage prices increase. This practice can be of interest in grassland systems to overcome certain climatic hazards without having to resort to purchases or to increase the farm's forage autonomy.

Changes in salivary analytes in cows due to the in vitro presence of feed

BACKGROUND

The effect in a sialochemistry profile of the presence of usually available feed in dairy cows was evaluated by an in vitro experiment. For this purpose, a pooled clean saliva from five healthy dairy cows was incubated five times with a standard feed based on a total mixed ration (F), wheat hay (H), and grass (G). The salivary panel was integrated by biomarkers of stress (cortisol -sCor-, salivary alpha-amylase -sAA-, butyrylcholinesterase -BChE-, total esterase -TEA-, and lipase -Lip-), immunity (adenosine deaminase -ADA-), oxidative status (Trolox equivalent antioxidant capacity -TEAC-, the ferric reducing ability of saliva -FRAS-, the cupric reducing antioxidant capacity -CUPRAC-, uric acid, and advanced oxidation protein products -AOPP-), and enzymes, proteins, and minerals of general metabolism and markers of liver, muscle, and renal damage (aspartate aminotransferase -AST-, alanine aminotransferase -ALP-, γ-glutamyl transferase -gGT-, lactate dehydrogenase -LDH-, creatine kinase -CK-, creatinine, urea, triglycerides, glucose, lactate, total protein, phosphorus, and total calcium).

RESULTS

Most of the evaluated analytes showed a coefficient of variations (CV) higher than 15% and/or significant changes compared with the clean saliva when feed was present. Some analytes, such as the oxidative status biomarkers (CV > 80%), AST (CV > 60%), or glucose (CV > 100%), showed significant changes with all the feed types tested. Others showed significant differences only with certain types of feed, such as LDH with F (CV > 60%) or triglycerides with F (CV > 100%) and H (CV > 95%). However, sCor or gGT remained unchanged (CV < 15%, P > 0.05) in all the treatments.

CONCLUSIONS

The presence of feed can produce changes in most of the analytes measured in cows' saliva, being of high importance to consider this factor when saliva is used as a sample to avoid errors in the interpretation of the results.

A high-starch vs. high-fibre diet: effects on the gut environment of the different intestinal compartments of the horse digestive tract

Background

Horses are often fed high amounts of starch in their diets despite the well-established benefits of a fibre-based diet to promote gut health and animal welfare. The aim of the present study was to compare the effects of two different diets – one based on high amounts of starch (HS) vs. one base on high amounts of fibre (HF) – on specific parameters of the gut environment across different intestinal compartments of the horse digestive tract. To this end differences in the gastrointestinal environment between HS vs. HF fed horses were assessed in terms of dry matter, organic matter and ash content; the particle size distribution and volatile fatty acid composition were also investigated.

Results

Nineteen Bardigiano horses of 14.3 ± 0.7 months of age and destined to slaughter were divided into two group pens – one fed with high amounts of starch (HS; n = 9; 43% hay plus 57% starch-rich pelleted feed); vs. fed with high amounts of fibre (HF; n = 10; 70% hay plus 30% fibre-rich pelleted feed). Horses fed HS diet presented a higher dry matter content in the right dorsal colon. Moreover, they showed a higher organic matter and ash content in the sternal flexure, pelvic flexure, right dorsal colon and rectum. In these latter intestinal compartments, horses fed a HS diet also showed a higher proportion of particles retained on an 8 mm sieve and a higher proportion of particles that washed through the finest sieve (< 1 mm). Moreover, the total amounts of volatile fatty acids as well as valeric acid were found to be significantly higher in horses fed the HS vs. HF diet.

Conclusions

A high-starch diet causes significant changes in the horse gut environment. We observed an increase in the dry matter content in the right dorsal colon, as well as reduced particle sizes and an increase in the production of valeric acid in all the gut compartments studied. High-starch diets should be avoided in favour of fibre-based diets with the goal of safeguarding gut health in horses.

Defining Fatty Acid Changes Linked to Rumen Development, Weaning and Growth in Holstein-Friesian Heifers

After birth, as effectively monogastric animals, calves undergo substantial physiological changes to become ruminants by 3 months of age and reach sexual maturity at approximately 15 months of age. Herein, we assess longitudinal metabolomic changes in Holstein-Friesian (HF) heifers from birth until sexual maturity during this developmental process. Sera from 20 healthy, HF heifers were sampled biweekly from 2 weeks of age until 13 months of age and then monthly until 19 months of age. Sera were assessed using flow infusion electrospray high-resolution mass spectrometry (FIE-HRMS) on a Q Exactive hybrid quadrupole-Orbitrap mass spectrometer for high-throughput, sensitive, non-targeted metabolite fingerprinting. Partial least squares discriminant analysis (PLS-DA) and unsupervised hierarchical clustering analysis (HCA) of the derived metabolomes indicated changes detectable in heifers’ sera over time. Time series analyses identified 30 metabolites that could be related to rumen development and weaning at ~3 months of age. Further time series analysis identified 40 metabolites that could be correlated with growth. These findings highlight the role of acetic acid and 3-phenylpropionate (3-PP) in rumen development and growth, suggest that weaning induces elevated levels of fatty acyls in response to a post-weaning stress-induced innate immune response and demonstrate the utilization of fatty acyls in growth. The identified metabolites offer serum metabolites which could inform the nutrition and healthy development of heifers.

When changing the hay makes a difference: A series of case reports

Dry hay (composed of grass, legumes, or a mixture of the two) provides the primary source of alimentary fiber in stabled horses with limited access to fresh pasture. However, hay can also give rise to health problems in the horse, depending on the quality and quantity of its components. Pathologies may be rooted in biological problems, such as inadequate digestion disturbances, or reflect mechanical difficulties - for example, due to the presence of sharp plant parts that irritate the oral mucosa, or due to physical intake problems that inhibit consumption. Unwanted plants in the hay may cause stomatitis and affect the oral mucosa, resulting in inappetence, hemorrhagic drooling, gingival hyperemia, edema, and ulcerative lesions, as reported in case 1 of the present study. Horse dysphagia, defined as a difficult in ingesting feed through the mouth and esophagus, is another important cause of malnutrition in the horse, and identifying the site of its origin is important in order to provide practical advice for nutritional management, as reported in case 2. Free fecal water syndrome (FFWS) is a condition where the horse exhibits two-phase feces expulsion, with an initial solid phase followed by a liquid phase. Although the etiology of FFWS is still unknown, hay quality seems to play a key role, as the outcome of case 3 suggests. This case series highlights the importance of hay quality and of providing an appropriate and adequate fiber intake. Moreover, good hay management becomes crucial when horses are affected by contextual pathologies, such as stomatitis, dysphagia, or FFWS.