Reticulorumen pH Research Articles

Short-Term Effects of Heat Stress on Cow Behavior, Registered by Innovative Technologies and Blood Gas Parameters.

Heat stress (HS) is one of the key factors affecting an animal's immune system and productivity, as a result of a physiological reaction combined with environmental factors. This study examined the short-term effects of heat stress on cow behavior, as recorded by innovative technologies, and its impact on blood gas parameters, using 56 of the 1070 cows clinically evaluated during the second and subsequent lactations within the first 30 days postpartum. Throughout the experiment (from 4 June 2024 until 1 July 2024), cow behavior parameters (rumination time min/d. (RT), body temperature (°C), reticulorumen pH, water consumption (L/day), cow activity (h/day)) were monitored using specialized SmaXtec boluses and employing a blood gas analyzer (Siemens Healthineers, 1200 Courtneypark Dr E Mississauga, L5T 1P2, Canada). During the study period, the temperature-humidity index (THI), based on ambient temperature and humidity, was recorded and used to calculate THI and to categorize the data into four THI classes as follows: 1-THI 60-63 (4 June 2024-12 June 2024); 2-THI 65-69 (13 June 2024-18 June 2024); 3-THI 73-75 (19 June 2024-25 June 2024); and 4-THI 73-78 (26 June 2024-1 July 2024). The results showed that heat stress significantly reduced rumination time by up to 70% in cows within the highest THI class (73 to 78) and increased body temperature by 2%. It also caused a 12.6% decrease in partial carbon dioxide pressure (pCO2) and a 32% increase in partial oxygen pressure (pO2), also decreasing plasma sodium by 1.36% and potassium by 6%, while increasing chloride by 3%. The findings underscore the critical need for continuous monitoring, early detection, and proactive management to mitigate the adverse impacts of heat stress on dairy cow health and productivity. Recommendations include the use of advanced monitoring technologies and specific blood gas parameter tracking to detect the early signs of heat stress and implement more timely interventions.

Changes in Parameters Registered by Innovative Technologies in Cows with Subclinical Acidosis.

The hypothesis of this study was that there were changes in biomarkers registered by innovative technologies in cows with subclinical acidosis. The aim of this study was to identify changes in the in-line milk fat-to-protein ratio and cow feeding behaviors such as reticulorumen pH, reticulorumen temperature, cow activity, and water intake with subclinical acidosis. From a total of 98 cows, 59 cows were selected to meet the following criteria (2 or more lactations, with 31 days in milk (DIM)). The selected animals were separated into two groups based on general clinical examination and reticulorumen pH: the subclinical acidosis group (SCA, n = 23) and the healthy group (HC, n = 36). During the diagnosis of subclinical acidosis and following the clinical examination of the healthy group using the BROLIS HerdLine system, the daily averages of milk yield (kg/day), milk fat (%), milk protein (%), and the milk fat-to-protein ratio were recorded. Simultaneously, by using Smaxtec technology, reticulorumen parameters and cow activity, including pH, temperature (°C), rumination time (minutes/day), and water intake (hours/day), were registered. Changes in parameters measured using innovative technologies were able to identify cows with subclinical acidosis. Cows with subclinical acidosis had a lower reticulorumen pH by 18.8% (p < 0.0001), a decreased milk yield by 10.49% (p < 0.001), a lower milk fat-to-protein ratio by 11.88% (p < 0.01), and a decreased rumination time by 6.59% (p < 0.01). However, the activity of these cows was higher by 57.19% (p < 0.001) compared to healthy cows. From a practical point of view, we suggest that veterinarians and farmers track parameters such as reticulorumen pH, milk yield, milk fat-to-protein ratio, rumination time, and activity for the identification of subclinical acidosis.

Cattle are more motivated for a high-concentrate diet than Sudan grass hay, despite low reticulorumen pH.

Subacute ruminal acidosis (SARA) is characterized by chronic low ruminal pH, and occurs for feedlot cattle fed high-concentrate diets. Forages slow digestion and reduce acid production. We aimed to assess how motivated finishing cattle are to access forage (Sudan grass hay, SG) via their willingness to interact with an electrified barrier. Reticulorumen pH was measured to relate the results to digestive health. Twenty-eight animals fed a high-concentrate ration ad libitum had access to 4L of one of two treatments (n = 14/treatment) fed 1×/d behind a barrier: 1) SG or 2) an additional offering of the normal ration (total mixed ration [TMR]). To access their treatment, the steer voluntarily pushed his muzzle against an electrified barrier. The electrical current was increased exponentially every 24h (0, 156, 312, 625, 1,250, 2,500, 5,000 µA) until the animal ceased accessing it. Visits to the treatment were recorded continuously 24h/d and reticulorumen pH was measured every 10min. Time with a reticulorumen pH below 5.8 was 348 ± 101 and 280 ± 76 min/24 h for SG and TMR animals, respectively; these durations meet the criterion for SARA. However, animals with access to SG were less likely to advance to the next current than TMR animals (P < 0.01) and were approximately 3× less willing to interact with higher currents than TMR (mean maximum current touched: 469 ± 169 and 1,380 ± 254 μA, respectively, mean ± SE, P = 0.01). Lower motivation to access SG was further demonstrated through fewer visits to the SG (2.4 ± 0.4 vs. 5.3 ± 0.6 #/d, P < 0.01), and less SG consumed than TMR (32.0 ± 0.1 vs. 74.0 ± 0.0 %/d, P < 0.01, measured as % due to weight differences of SG and TMR). Overall, finishing cattle valued the TMR more than SG, likely because of differences in the quantity offered, palatability, and familiarity. When rumen health was considered, SG animals visited more often (r = 0.5, P = 0.09) and showed fewer failed attempts (r = -0.5, P = 0.06) to access forage as the severity and duration of pH depression below 5.6, for example, increased. No measures of treatment use were related to pH depression for TMR animals (P ≥ 0.31). These findings provide evidence that cattle are motivated for Sudan grass hay when experiencing chronic low reticulorumen pH. However, they also contribute to the mixed evidence about the motivation for forage in this life stage, because, overall TMR was valued more highly than SG. Despite widespread pH depression, TMR cattle contrafreeloaded for additional concentration, demonstrating unexpectedly high motivation for this resource.

Effect of pre- and postpartum supplementation of a pure glycerol product to dairy cows on feeding behavior, lying behavior, and reticulorumen pH

The objective of this study was to quantify the effects of supplementing a low level of dry glycerol product pre- and postpartum on the feeding behavior, lying behavior, and reticulorumen pH of dairy cows. Multiparous Holstein dairy cows (n = 60) were enrolled in a 2 × 2 factorial design study. Twenty-one days before expected parturition, cows individually received a dry cow diet with (1) 250 g/d glycerol supplementation (GLY; 66% pure glycerol, United States Pharmacopeia grade), or (2) no supplementation (CON). Following parturition, cows were individually assigned to either (1) 250 g/d glycerol product (GLY; 66% pure glycerol), or (2) no supplementation (CON) to their partial mixed ration (PMR) for the first 21 d in milk (DIM). All cows were milked by an automated milking system and offered a target of 5.4 kg/d pellet (23% of target total dry matter intake [DMI]). For both treatment periods, cows were individually assigned to automated feed bins to measure PMR feeding behavior. Rumination time and lying behavior were monitored with electronic sensors for the whole study (-21 to 21 DIM). Reticulorumen pH boluses were administered to a subset of cows (n = 40) where pH was recorded every 10 min from 21 d prepartum to 21 d postpartum. Prepartum, cows fed GLY had fewer, larger meals and spent 20.2% more time feeding than CON while consuming feed at a similar rate. Cows on the CON diet prepartum spent more time lying down in more frequent bouts in the 21 d before calving. Following parturition, cows that received GLY prepartum continued to devote more time to eating, while tending to spend less time ruminating per kilogram of DMI. Cows receiving CON postpartum had larger meals with longer intervals between meals. In the first 21 DIM, cows receiving CON prepartum tended to have shorter, but significantly more frequent, lying bouts than cows fed GLY prepartum. Glycerol supplementation pre- and postpartum resulted in less time spent lying down following parturition. Minimal differences between treatments were observed for pre- and postpartum sorting behavior or reticulorumen pH. Overall, supplementation of glycerol pre- and postpartum altered cow time budgets, with cows spending more time eating pre- and postpartum, less time lying pre- and postpartum, and having fewer, larger meals prepartum when receiving glycerol prepartum, and with cows having slower feeding rates and smaller meals following parturition with postpartum glycerol supplementation.

O67 A score including indicators of reticulo-rumen (RR) pH kinetics to characterize subacute ruminal acidosis (SARA) in dairy cows

O67 A score including indicators of reticulo-rumen (RR) pH kinetics to characterize subacute ruminal acidosis (SARA) in dairy cows

The Relationship between Reticuloruminal Temperature, Reticuloruminal pH, Cow Activity, and Clinical Mastitis in Dairy Cows

We hypothesized that reticuloruminal temperature, pH as well as cow activity can be used as parameters for the early diagnosis of clinical mastitis in dairy cows. Therefore, we aimed to detect the relationship between these factors and the disease. We randomly selected cows with clinical mastitis and clinically healthy cows (HG) out of 600 milking cows. We recorded the following parameters during the experiment: reticulorumen temperature (RR temp.), reticulorumen pH (RR pH), and cow activity. We used smaXtec boluses (smaXtec animal care technology®, Graz, Austria). In this investigation, reticulorumen data obtained seven days before diagnosis were compared to HG data from the same time period. CM cows were observed on the same days as the healthy cows. The healthy group’s RR pH was 7.32% higher than that of cows with CM. Reticulorumen temperature was also 1.25% higher in the CM group than in the control group. The healthy group had a higher average value for walking activity, which was 17.37% higher than the CM group. The data of reticulorumen pH changes during 24 h showed that during the day, the pH changed from 5.53 to 5.83 in the CM group. By contrast, pH changed from 6.05 to 6.31 in the control group. The lowest reticulorumen pH in the CM group was detected on the third day before diagnosis, which was 15.76% lower than the highest reticulorumen pH detected on the sixth day before diagnosis. The lowest reticulorumen pH in CM cows was detected at 0 and 1 days before diagnosis and it was 1.45% lower than the highest reticulorumen pH detected on the second day before diagnosis. The lowest walking activity in the CM group was detected 0 days before diagnosis, which was 50.60% lower than on the fifth day before diagnosis. Overall, the results confirmed our hypothesis that reticuloruminal temperature, reticuloruminal pH, and cow activity could be used as parameters for the early diagnosis of clinical mastitis in dairy cows.

Use of Innovative Tools for the Detection of the Impact of Heat Stress on Reticulorumen Parameters and Cow Walking Activity Levels.

The aim of this study was to evaluate the influence of the temperature and humidity index on reticulorumen parameters such as temperature, pH, rumination index, and cow walking activity levels. Throughout the experiment, the following parameters were recorded: reticulorumen pH (pH), reticulorumen temperature (RR temp.), reticulorumen temperature without drinking cycles, ambient temperature, ambient relative humidity, cow walking activity levels, heat index, and temperature-humidity index (THI). These parameters were registered with particular smaXtec boluses. SmaXtec boluses were applied on 1 July 2022; 24 days were the adaptation period. Measurements started at 25 July 2022 and finished at 29 August 2022. The THI was divided into two classes: THI < 72 (comfort zone) and THI ≥ 72 (higher risk of thermal stress). Cows assigned to the 2nd THI class had lower average values for pH, temperature, and rumination index, but not walking activity levels. The mean differences ranged from 0.36 percent in temperature to 11.61 percent in walking activity levels (p < 0.01). An analysis of the THI revealed a significant positive linear relation with hours, where the THI had a tendency to increase on average by 0.2403. The reticuloruminal pH showed a negative linear relation with hours, where the reticuloruminal pH had a tendency to decrease on average by 0.0032, p < 0.001. Data analysis revealed a significant positive linear relationship between walking activity levels and hours, where walking activity levels had a tendency to increase on average by 0.0622 steps per hour, p < 0.001. The rumination index was not significantly related to hours (p < 0.005), although the rumination index had a tendency to increase by 0.4376 per hour, p > 0.05. The influence of HS on reticulorumen parameters increased the risk of acidosis and cows' activity levels. HS had a negative impact on reticulorumen pH, temperature, and the rumination index. A higher THI (≥72) increased the risk of ruminal acidosis and decreased cows' physical activity levels. From a practical point of view, we can use innovative tools for the detection of HS and its impact on reticulorumen parameters and cow walking activity levels.

On-farm evaluation of multiparametric models to predict subacute ruminal acidosis in dairy cows

This research aimed: (i) to evaluate on-farm (FARM data) multiparametric models developed under controlled experiment (INRAE data) and based on non-invasive indicators to detect subacute ruminal acidosis (SARA) in dairy cows. We also aimed to recover high discrimination capacity, if needed, by (ii) building new models with combined INRAE and FARM data; and (iii) enriching the models increasing from 2 to 5 indicators per model. For model enrichment, we focused on indicators determinable on-farm by quick and inexpensive routine analysis. Fifteen commercial dairy farms were selected to cover a wide range of SARA risk. In each farm, four Holstein early-lactating healthy primiparous cows were selected based on their last on-farm recording of milk yield and somatic cell count analysis. Cows were equipped with a reticulo-rumen pH sensor. The pH kinetics were analysed over a subsequent 7-day period. Relative pH indicators were used to classify cows with or without SARA. Milk, blood, faeces, and urine were collected for analysis of the indicators included in the models developed by Villot et al. (2020) on INRAE data that were externally evaluated using FARM data. Then, new models based on the same indicators were developed combining INRAE and FARM data to test whether a possible loss in performance was due to a limited validity domain of model by Villot et al (2020). Finally, the models developed combining INRAE and FARM data were adapted to the on-farm application and enriched by increasing indicators from 2 to 5 per model using linear discriminant analysis and leave-one-out cross-validation. The sensitivities (true-positive rate) in external evaluation on FARM data were substantially lower than those from cross-validation by Villot et al. (2020) (range: 0.1–0.75 vs 0.79–0.96, respectively), and the specificities (true-negative rate) showed a larger range with lower minimum values (range: 0.18–1.0 vs 0.62–0.97, respectively). The sensitivities of new models developed combining INRAE and FARM data ranged from 0.63 to 0.77. Models involving blood cholesterol, β-hydroxybutyrate, haptoglobin, milk and blood urea, and models involving milk fat/protein ratio, dietary starch proportion, and milk fatty acids had the highest performances, whereas models including sieved faecal residues and urine pH had the lowest. Enriching models to three indicators per model improved sensitivity and specificity, but the inclusion of more indicators was less or not effective. Larger field trials are required to validate our results and to increase variability and validity domain of models.

Relationship between Reticulorumen Parameters Measured in Real Time and Methane Emission and Heat Stress Risk in Dairy Cows.

The objective of this study was to investigate a connection between CH4 emissions and reticulorumen pH and temperature. During the experiment, we registered the following parameters: reticulorumen pH (pH), reticulorumen temperature (RR temp.), reticulorumen temperature without drinking cycles, ambient temperature, ambient relative humidity, cow activity, heat index, temperature-humidity index (THI), and methane emissions (CH4). The experimental animals were divided into two groups based on the reticulorumen pH: 1. pH &lt; 6.22 and 2. pH 6.22-6.42. We found that cows assigned to the second pH class had higher (46.18%) average values for methane emissions (p &lt; 0.01). For the other indicators, higher average values were detected in cows of the first pH class, RR temperature (2.80%), relative humidity (20.96%), temperature-humidity index (2.47%) (p &lt; 0.01), and temperature (3.93%) (p &lt; 0.05), which were higher compared to cows of the second pH class. Reticulorumen pH was highly negatively correlated with THI and temperature (r = -0.667 to 0.717, p &lt; 0.001) and somewhat negatively with heat index, relative humidity, and RR temperature (r = -0.536, p &lt; 0.001; r = -0.471 to 0.456, p &lt; 0.01). Cows with a higher risk of heat stress had a higher risk of lower reticulorumen pH.

Impact of feed supplement with alfa-amylase and beta-glucanase on ingestive-related biomarkers registered with real-time sensors.

The aim of this study was to investigate the impact of feed supplements with alfa-amylase and beta-glucanase (Optipartum C+ 200) on ingestive-related behaviour biomarkers registered with real-time sensors: rumination behaviours and reticulorumen parameters (pH and temperature). Cows (n=20) in the treatment group (TG) were fed with Optipartum C+ 200 (Enzymes feed supplement: Alfa-Amylase 57 Units; Beta-Glucanase 107 Units) from 21 days before calving until 30 days after calving with a feeding rate of 200 g/cow/day. Cows (n=22) in the control group (CG) were fed a feed ration without feed supplement. Measurements started from 6 days before calving and continued until 21 days after calving. The following indicators were registered: with the RumiWatch System: Rumination time; Eating time; Drinking time; Rumination chews; Eating chews; Drinking gulps; Bolus; Chews per minute; Chews per bolus. With the SmaXtec system: the temperature, pH of the contents of the cows' reticulorumens, and cows' walking activity. According to our results, feed supplementation with alfa-amylase and beta-glucanase (Optipartum C+ 200) in the TG group resulted in increases in the following parameters: 9% rumination time and eating time, 19% drinking time, 11% rumination chews, 16% eating chews, 13% number of boluses per rumination, 5% chews per minute and 16% chews per bolus. The rumination time showed a strong, positive relation with rumination chews and bolus indicators in both groups (TG and CG) (p⟨0.001); while the rumination time in both groups of cows showed an opposite direction and was negatively related to eating time and eating chews (p⟨0.05). We found a 1.28 % lower reticulorumen pH and a 0.64 % lower reticulorumen temperature in cows fed with the supplement compared with cows in the control group. Cows in TG were 8.80% more active than those in the CG group. For improvement of ingestive-related behaviour we suggest adding a feed supplement with alfa-amylase and beta-glucanase (Optipartum C+ 200).

Evaluation of the reticulorumen pH throughout the feeding period for beef feedlot steers maintained in a commercial feedlot and its association with liver abscesses.

To evaluate the reticulorumen pH of beef feedlot steers throughout the feeding period and to assess the association between the respective durations that the reticulorumen pH was ≤ 5.6 (subacute ruminal acidosis) and ≤ 5.2 (acute ruminal acidosis) and liver abscess severity. 59 feedlot steers (mean body weight, 349.5 kg). On day 0, each steer was orally administered an electronic bolus that monitored the reticulorumen pH every 10 minutes for 150 days. Steers were transitioned from a starter to intermediate ration on day 8 (transition 1) and from the intermediate to finish ration on day 19 (transition 2). The ration carbohydrate and megacalorie contents increased with each transition. During each transition, the lower megacalorie ration was fed at the 8:00 am feeding and the higher megacalorie ration was fed at the 2:00 pm feeding for 3 days before the higher megacalorie ration was fed extensively. Steers were sent to slaughter after 182 days; each carcass was assessed for liver abscesses. The diurnal reticulorumen pH pattern was characterized by a peak at 7:00 am and nadir at 8:00 pm. The mean percentages of time that the reticulorumen pH was ≤ 5.6 and ≤ 5.2 were more than 10-fold greater during transition 1, compared with during transition 2, and were significantly greater for steers with extensive liver abscesses than for steers without extensive liver abscesses. Efforts to minimize the duration that the reticulorumen pH is ≤ 5.6 might mitigate liver abscess formation in feedlot cattle.

Evaluation of biomarkers of heat stress using automatic health monitoring system in dairy cows

The aim of this study was to evaluate biomarkers of heat stress (HS) from an automatic milking system (AMS), the relationships between measurements of the temperature-humidity index (THI), reticulorumen pH and temperature, and some automatic milking systems parameters in dairy cows (rumination time (RT), milk traits, body weight (BW) and consumption of concentrate (CC)) during the summer period. Lithuanian Black and White dairy cows (n=365) were selected. The cows were milked with Lely Astronaut® A3 milking robots with free traffic. Biomarkers were collected from the Lely T4C management program for analysis. The pH and temperature of the contents of the cow reticulorumen were measured using specific Smax-tec boluses. The farm zone's daily humidity and air temperature were obtained from the adjacent weather station (2 km away). According to this study, during HS, the higher THI positively cor- relates with milk lactose (ML), which increases the risk of mastitis and decreases CC, RT, BW, MY, reticulorumen pH, and F/P. Some biomarkers of HS can be milk yield, milk lactose, somatic cell count, concentrate intake, rumination time, body weight, reticulorumen pH, and milk fat - protein ratio. We can recommend monitoring these parameters in the herd management program to identify the possibility of heat stress.

Can reticulorumen ph, temperature and cow activity registered before calving act as biomarkers of diseases after calving?

The aim of this study was to determine if reticulorumen ph, temperature and cow activity registered before calving can serve as indicators of diseases after calving.The cows were selected according to those fitting the profile of having had two or more lactations (on average 2.9±0.13 lactations), from 60 to 0 days before and the first 30 days after calving, and being clinically healthy. The clinical examination (identification of diseases after calving) was performed from 60 days before calving to 60 days after calving. Diseases after calving were diagnosed based on clinical symptoms specific to these diseases. The pH and temperature of the contents of the cow reticulorumens and cow activity were measured using specific smaX-tec boluses manufactured for animal care.We found that the highest pH and temperature before calving can serve as biomarkers of healthy cows after calving. The lowest reticulum temperature before calving can serve as an indicator of MF after calving. A positive correlation of reticulum pH and temperature before calving can serve as biomarkers of PR. Decreasing cow activity before calving can serve as an indicator of diseases after calving. For calving prognosis, temperature of the reticulorumen can be used; it decreased 6-7 days before calving.

Effects of molasses-based liquid feed supplementation to a high-straw dry cow diet on feed intake, health, and performance of dairy cows across the transition period

The objective of this study was to determine the effects of adding molasses-based liquid feed to a high-straw dry cow diet on intake, behavior, health, and performance of dairy cows across the transition period. Holstein cows (n = 40) entering their second lactation or greater were enrolled at dry-off (∼45 d before expected calving) and assigned to 1 of 2 treatments: a high-straw dry cow total mixed ration (TMR) with either (1) no molasses [CON; n = 20; 10.7% crude protein (CP), 1.45 Mcal/kg of net energy for lactation (NEL)] or (2) supplemented with 1 kg/cow daily [dry matter (DM) basis] of molasses-based liquid feed (LF; n = 20; 11.2% CP, 1.49 Mcal/kg of NEL). At calving all cows were fed the same lactating TMR (14.9% CP, 1.68 Mcal/kg of NEL) and followed for 28 d. During the dry period, cows fed the LF diet had greater DM intake (15.3 ± 0.24 vs. 13.4 ± 0.24 kg/d) and tended to have a shorter interval between meals (192.8 ± 8.38 vs. 216.5 ± 7.97 min) and more frequent meals (6.3 ± 0.27 vs. 5.6 ± 0.27 meals/d), while consuming their feed faster (0.09 ± 0.001 vs. 0.08 ± 0.001 kg of DM/min) compared with cows fed the CON diet. Regardless of treatment, cows sorted [100% × (actual intake/predicted intake)] against the longest ration particles (>19 mm), with cows fed the CON diet sorting more against these (81.1 ± 2.6 vs. 93.9 ± 2.6%). Cows fed the CON diet did not sort for or against short particles (<8, >4 mm; 100.2 ± 0.31%), but cows fed the LF diet tended to sort against these (99.2 ± 0.31%). Post-calving, cows fed the LF diet did not sort for long particles (98.5 ± 1.1%), but cows fed the CON diet continued to sort against these (96.3 ± 1.1%). Cows fed the LF diet had higher mean reticulorumen pH in the dry period (6.4 ± 0.05 vs. 6.2 ± 0.06 pH), in the first week after calving (CON = 5.7 ± 0.06 pH, LF = 5.8 ± 0.06 pH), and tended to have higher mean reticulorumen pH in the second week after calving (CON = 5.7 ± 0.06 pH, LF = 5.9 ± 0.06 pH). The results suggest that supplementing a molasses-based liquid feed in high-straw dry cow diets may improve intake and consistency in nutrients consumed during the dry period and in early lactation, as well as possibly promoting better rumen health across the transition period.

Biomarkers from automatic milking system for cows reproduction success

This Research Communication addresses the hypothesis that some biomarkers from automatic milking system can be indicators of cows reproduction success. The pregnancies were tested with ultrasound after 30–35 d post-insemination. Those cows which were pregnant were assigned to the PG+ group (n = 36) and those which were not pregnant, were assigned to the PG- group (n = 32). On oestrus day the pH, temperature of the contents of cow reticulorumens and cow activity were measured using specific smaX-tec boluses manufactured for animal care. Rumination time, body weight, milk yield, milk fat – protein ratio, milk lactose, milk somatic cell count, milk electric conductivity of all quarters of udder (front right, front left, rear left, rear right), and consumption of concentrates were registered with the help of Lely Astronaut® A3 milking robots.We estimated that the reticulorumen pH (P < 0.001) and reticulorumen temperature (P < 0.01) were higher in PG+ cows compared to PG− cows, which were found to have higher (P < 0.001) productivity (MY). Between the reticulorumen pH and the MY in PG− cows a positive relationship was calculated (P<0.001). In PG+ group was estimated a higher milk fat ant protein ratio (F/P = 1.19 ± 0.013) compared to PG− group (P < 0.001) and a higher content of milk lactose (4.59 ± 0.003%; P < 0.001). Cows of PG + group were more active compared to the PG− group (1.94%; P < 0.001) and consumed less concentrates (17.50%, P < 0.001). We can conclude that higher reticulorumen pH and temperature, milk lactose and lower consumption of concentrates and higher activity of cows were associated with the reproduction success. Correlation coefficients between values of automatic measurements of reticulorumen pH and temperature in PG+ and PG− cows were fluctuating and differed at different times of day. Analysis multivariable logistic regression have shown that the key reliable indicators of cow reproduction success are changes in productivity and activity.

Inline Reticulorumen pH as an Indicator of Cows Reproduction and Health Status.

Our study hypothesis is that the interline registered pH of the cow reticulum can be used as an indicator of health and reproductive status. The main objective of this study was to examine the relationship of pH, using the indicators of the automatic milking system (AMS), with some parameters of cow blood components. The following four main groups were used to classify cow health status: 15–30 d postpartum, 1–34 d after insemination, 35 d after insemination (not pregnant), and 35 d (pregnant). Using the reticulum pH assay, the animals were categorized as pH < 6.22 (5.3% of cows), pH 6.22–6.42 (42.1% of cows), pH 2.6–6.62 (21.1% of cows), and pH > 6.62 (10.5% of cows). Using milking robots, milk yield, fat protein, lactose level, somatic cell count, and electron conductivity were registered. Other parameters assessed included the temperature and pH of the contents of reticulorumens. Assessment of the aforementioned parameters was done using specific smaX-tec boluses. Blood gas parameters were assessed using a blood gas analyzer (EPOC (Siemens Healthcare GmbH, Erlangen, Germany). The study findings indicated that pregnant cows have a higher pH during insemination than that of non-pregnant ones. It was also noted that cows with a low fat/protein ratio, lactose level, and high SCC had low reticulorumen pH. They also had the lowest blood pH. It was also noted that, with the increase of reticulorumen pH, there was an increased level of blood potassium, a high hematocrit, and low sodium and carbon dioxide saturation.

Effects of a Megasphaera elsdenii oral drench on reticulorumen pH dynamics in lactating dairy cows under subacute ruminal acidosis challenge

Subacute ruminal acidosis (SARA) is an important disorder in dairy cattle with economic and animal welfare implications. A preventive strategy for SARA control is oral drenching of probiotics, such as Megasphaera elsdenii. The aim of this study was to evaluate the effects of a M. elsdenii oral drench on reticulorumen pH, milk yield and components, and feeding behavior of lactating cows under a SARA challenge. This study consisted of two crossover trials with 8 cows each to determine the efficacy of drenching live culture of M. elsdenii NCIMB 41125. Experimental period of each trial lasted 8 d with a 4 wk washout interval between periods. The first 3 d of each period were considered baseline days. On day 4 of the period, feed delivered was reduced by half, based upon individual mean dry matter intake (DMI) during the baseline period. On day 5 of the period, all cows received a challenge diet rich in highly fermentable carbohydrates offered to the cows for 2 h to induce SARA. Orts were weighed and replaced with regular diet offered ad libitum. The last 3 d of each experimental period were considered recovery days. The difference between each trial was the administration time of M. elsdenii drench, where in Trial 1 it was delivered 4 d before (PRO-4) and in Trial 2 it was delivered the day before (PRO-1) the SARA challenge. Cows were randomly assigned to either a treatment (PRO-4 or PRO-1) or control (CON-4 or CON-1) drench, and reversed on the subsequent period. During Trial 1, PRO-4 cows produced more milk (P < 0.01), with greater protein percentage (P = 0.03) and lesser fat to protein ratio (P = 0.01) compared with control cows. PRO-4 cows also had greater overall reticulorumen pH and experienced shorter and less intense acidosis (P < 0.05) and greater DMI (P = 0.04) compared with control cows. Feeding behavior was not affected by treatment in Trial 1 (P > 0.10). In Trial 2, only feeding time was affected by the treatment, with PRO-1 cows spending more minutes per day feeding (P < 0.01) compared to control cows. The results indicate potential benefits of a M. elsdenii drench on rumen pH dynamics, acidosis resilience, and possibly milk production and feed intake. However, it appears that the time of drench administration might influence M. elsdenii establishment and drench efficacy.

PSI-6 The impact of Saccharomyces cerevisiae on animal performance and rumen health indicators during the late finishing phase for feedlot steers

Abstract The objective of this study was to evaluate the addition of active dry Saccharomyces cerevisiae (yeast) to the diet of steers during the late finishing phase on performance, rumen pH and mRNA expression of genes relating to barrier function and immune response. 54 steers were blocked by weight and randomly assigned to one of two treatments: control (CON; n = 27) or yeast (fed at 60B CFU/hd/d; VistaCell, AB Vista, YST; n = 24). The corn-based finisher (60% high moisture corn, 20% dried distillers grains, and 17% alfalfa haylage, DM basis) ration was fed for 55± 15.9 days until slaughter. Every 28 days, weight and ultrasound of back and rump fat depths were recorded. Three to five days before slaughter, blood was collected via jugular venipuncture for measures of circulating metabolites, serum amyloid-A, and haptoglobin. Reticulo-rumen pH was recorded using an in-dwelling probe for 4 weeks leading up to slaughter. Rumen papillae were obtained for histological measurements, and to assess mRNA expression of genes related to gut barrier function (OCLN, CLDN, ZO1, ZO2) and immune response (TLR2, TLR4, FCAR). Data were analyzed as a complete randomized block design using PROC GLIMMIX in SAS, with treatment as a fixed effect, and block as a random effect. Feeding yeast in the late finisher diet decreased dry matter intake (11.97 and 8.24 ± 0.507 kg/day for CON and YST, respectively; P &amp;lt; 0.001) while maintaining average daily gains (P = 0.50), therefore improving feed conversion (P &amp;lt; 0.001) for YST steers. No differences were found between CON and YST steers for blood metabolites, including immune response markers (P ≥ 0.13), rumen mRNA expression (P ≥ 0.07), and rumen pH (P ≥ 0.08). Yeast addition to the late finishing diet significantly improved feed conversion through the decrease in dry matter intake without impacts on carcass quality or animal performance.

Effects of wheat straw chop length in high-straw dry cow diets on intake, health, and performance of dairy cows across the transition period

The study investigated the effect of chop length of wheat straw in a high-straw dry cow diet on the feeding behavior, health, and performance of Holstein dairy cows across the transition period. Forty cows were enrolled at dry off, approximately 45 d before expected calving, and assigned to 1 of 2 dietary treatments containing (on a dry matter basis) 36% corn silage, 35% dry cow pellet, and 29% wheat straw. Diets were formulated to target an energy consumption of 19 Mcal/d of net energy for lactation per cow. The diets differed in the chop length of wheat straw: (1) long straw chopped with a 10.16-cm screen (LDD; n = 20), or (2) short straw chopped with a 2.54-cm screen (SDD; n = 20). Dietary treatments were fed throughout the dry period. Feeding behavior, rumination time, and reticulorumen pH were monitored electronically, and feed samples were collected to determine feed sorting. Blood samples were taken weekly, and body condition scores and body weights were taken every 2 wk. Postcalving, all cows were fed the same lactating cow total mixed ration for 28 d; the same measurements were recorded with the addition of daily milk yield and twice weekly milk components. During the dry period, cows fed the SDD treatment consumed more dry matter (15.6 vs. 15.0 kg/d), had more consistent dry matter intake in the week leading up to calving, had a faster feeding rate, consumed 0.4 kg/meal more, and had 0.6 fewer meals per day. No differences were observed in rumination time or mean reticulorumen pH between treatments in both the dry and lactating period. Regardless of treatment during the dry period, cows sorted against the long particles (>19 mm) and in favor of the short particles (<8, >4 mm), but cows fed the LDD treatment sorted to a greater extent than cows fed the SDD treatment. Dietary treatment in the dry period did not influence feed sorting behavior postcalving. Cows fed the LDD treatment had a greater daily change (decline) in rumen pH in the first week postcalving and had a greater blood β-hydroxybutyrate concentration in the third week postcalving. Overall, the results from this study indicate that feeding shorter chopped wheat straw in a high-straw dry cow diet improved intake, reduced sorting during the dry period, and resulted in greater metabolic health and rumen stability in early lactation.

Feeding a marine-based rumen buffer increases milk production and decreases time of low reticulo-rumen pH in grazing dairy cows offered perennial ryegrass-based pasture

Dairy cows grazing highly digestible perennial ryegrass-based pastures are reportedly susceptible to low rumen pH. This experiment investigates the effect of feeding a novel marine-based rumen buffering product on milk production, milk composition and reticulo-rumen pH in dairy cows grazing perennial ryegrass-based pasture supplemented with concentrates. Three primiparous and twenty-one multiparous spring calving dairy cows (58 ± 12.6 days in milk) were blocked by parity (3.2 ± 1.56) and pre-experimental milk yield (36.0 ± 6.55 kg) and randomly assigned to three experimental treatments in a three-period crossover-design experiment. Dietary treatments consisted of Control; 8 kg of a commercial cereal-based compound, BUF1; control diet +70 g of a novel marine-based buffer (a mix containing only calcified seaweed and a marine source of magnesium oxide: see detailed analysis provided) and BUF2; control +140 g of the same marine-based buffer in a changeover design experiment. Experimental periods lasted for 35 d with 21 d for diet adaptation and a 14 d measurement period. In-dwelling reticulo-rumen pH probes recorded reticulo-rumen pH and temperature during d 58–63 (Period 2) and d 93–98 (Period 3) of this experiment. Cows fed BUF1 and BUF2 showed an increased milk yield of 1.20 kg/d and 1.07 kg/d respectively when compared to the Control diet (P = 0.004 and P = 0.012). There were increases in energy corrected milk yield (ECM) of 1.53 kg/d (P = 0.02) and 3.5% and 4% fat corrected milk (FCM) of 1.87 kg/d and 1.76 kg/d, respectively (P = 0.012), when cows were fed BUF2 compared to cows fed the Control. Number of minutes per treatment per day at reticulo-rumen pH < 5.8 and < 6.0 was significantly greater for cows fed Control compared to cows fed BUF2 (P<0.001). Results of this experiment suggest that supplementation with a novel marine-based rumen buffering product increased milk production and reduced the amount of time the reticulo-rumen was below pH 5.8 and 6.0 in grazing dairy cows supplemented with a cereal-based concentrate.