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.

Pressure measurement in the reticulum to detect different behaviors of healthy cows.

The aim of the current study was to investigate the relation between reticulorumen contractions and monitored cow behaviors. A purpose-built pressure measuring device was used and shown to be capable of detecting the known contraction patterns in the reticulorumen of four rumen-fistulated cows. Reticular pressure data was used to build a random forest algorithm, a learning algorithm based on a combination of decision trees, to detect rumination and other cow behaviors. In addition, we developed a peak-detection algorithm for rumination based on visual inspection of patterns in reticular pressure. Cow behaviors, differentiated in ruminating, eating, drinking, sleeping and 'other', as scored from video observation, were used to develop and test the algorithms. The results demonstrated that rumination of a cow can be detected by measuring pressure differences in the reticulum using either the random forest algorithm or the peak-detection algorithm. The random forest algorithm showed very robust performances for detecting rumination with an accuracy of 0.98, a sensitivity of 0.95 and a specificity of 0.99. The peak-detection algorithm could detect rumination robustly, with an accuracy of 0.92, a sensitivity of 0.97 and a specificity of 0.90. In addition, we provide proof of principle that a random forest algorithm can also detect eating, drinking and sleeping behavior from the same data with performances above 0.90 for all measures. The measurement device used in this study needed rumen-fistulated cows, but the results indicate that behavior detection using algorithms based on only measurements in the reticulum is feasible. This is promising as it may allow future wireless sensor techniques in the reticulum to continuously monitor a range of important behaviors of cows.

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.

The effectiveness of fibrolytic enzymes and active yeast on improving reticulorumen pH in dairy cows.

Exogenous fibrolytic enzymes (EFE) and yeast are feed supplements that improve forage digestion in rumen, but their influences on physical reticulorumen parameters are not well studied. This study was designed to evaluate the effect of the EFE:endo-ß-xylanase (37x104 U/cow/day), endocellulase (45x104 U/cow/day), endo-ß-glucanase (12x104U/cow/day), and active yeast - Saccharomyces cerevisiae CNCM-1077 (10x109CFU/cow/day) supplements on reticulorumen pH (RpH) and temperature (RT) in dairy cows. Nine Lithuanian Red cows were allocated into three groups (3 cows/group): control group (C) - farm diet without supplementation, enzyme group (E) - farm diet supplemented with EFE, enzyme and active yeast group (EY) - farm diet supplemented with EFE and active yeast. The feeding trial lasted for 60 d. All cows were equipped with reticuloruminal telemetric pH and temperature sensor device. Data provided by the device were used to calculate the mean RpH (RpH/24h), the mean minimal RpH (minRpH/24h) and mean of the time that RpH was below the threshold value of 6.0 (RpH⟨6.0/24h, min.). The highest RpH/24h (6.37±0.22) was observed in group EY and it was by 1.62% (p⟨0.05) and 1.27% (p⟨0.001) higher as compared with groups E and C, respectively. Also minRpH/24h (6.24±0.24) was highest in group EY and values were by 0.63% (p⟨0.001) and 0.65% (p⟨0.001) higher as compared with groups C and E, respectively. The shortest duration of RpH⟨6.0/24h, was recorded in group EY, and it was by 57.76% (p⟨0.05) and 47.87% shorter as compared with groups C and E, respectively. In conclusion, feed supplementation with EFE and Saccharomyces cerevisiae CNCM-1077 had beneficial effect on RpH.

Ruminal fatty acid outflow in dry cows fed different sources of linoleic acid: reticulum and omasum as alternative sampling sites to abomasum.

This study was designed to determine the rumen outflow of fatty acids (FA) and biohydrogenation (BH) extent using alternative sampling sites (reticulum and omasum) to abomasum in dry cows fed different sources of FA. Four Holstein non-pregnant dry cows (≥3 parturitions, and 712 ± 125 kg BW), cannulated in the rumen and abomasum, were randomly assigned to a 4 × 4 Latin square design experiment, containing the following treatments: 1) control (CON); 2) soya bean oil (SO), dietary inclusion at 30 g/kg; 3) whole raw soya beans (WS), dietary inclusion at 160 g/kg; and 4) calcium salts of FA (CSFA), dietary inclusion at 32 g/kg. Rumen outflow of nutrients was estimated using the three markers reconstitution system (cobalt-EDTA, ytterbium chloride, and indigestible neutral detergent fibre [NDF]). Diets with FA sources decreased feed intake and increased FA intake. No differences in nutrient intake and digestibility were detected among cows fed diets supplemented with different FA sources. Diets with FA sources reduced the rumen outflow of DM and NDF, hence decreasing their passage rates. In addition, SO diet reduced the ruminal outflow of DM and NDF in comparison with WS and CSFA. Omasal sampling yielded the highest values of rumen outflow of NDF and potentially degradable NDF (pdNDF), whereas the reticular and abomasal samplings yielded intermediate and least values, respectively. The interaction effect between diet and sampling site was observed for rumen outflow of majority FA (except for C16:0, C18:0, and C18:2 trans-10, cis-12) and BH extension of C18:1 cis, C18:2, and C18:3. Calculations derived from abomasal sampling revealed that WS and CSFA diets had lower BH extent of C18:1 cis and C18:2 in comparison with SO, whereas cows fed CSFA had greater BH extent of C18:3 and lower BH extent of C18:1 cis compared to those fed WS. However, the latter results were not similar when calculations were performed based on the reticular and omasal samplings. Thus, there is evidence that neither reticular nor omasal samplings are suitable for estimating rumen outflow of FA in dry cows. In addition, WS and CSFA diets can increase the abomasal flow of polyunsaturated FA in dry cows.

Evaluation of reticuloruminal pH measurements from individual cattle: Sampling strategies for the assessment of herd status.

The application of pH observations to clinical practice in dairy cattle is based on criteria derived primarily from single time-point observations more than 20 years ago. The aims of this study were to evaluate these criteria using data collected using continuous recording methods; to make recommendations that might improve their interpretation; and to determine the relationship between the number of devices deployed in a herd and the accuracy of the resulting estimate of the herd-mean reticuloruminal pH. The study made use of 815,475 observations of reticuloruminal pH values obtained from 75 cattle in three herds (one beef and two twice-daily milking herds) to assess sampling strategies for the diagnosis of sub-acute rumen acidosis (SARA), and to evaluate the ability of different numbers of bolus devices to accurately estimate the true herd-mean reticuloruminal pH value at any time. The traditional criteria for SARA provide low diagnostic utility, the probability of detection of animals with pH values below specified thresholds being affected by a strong effect of time of day and herd. The analysis suggests that regardless of time of feeding, sampling should be carried out in the late afternoon or evening to obtain a reasonable probability of detection of animals with pH values below the threshold level. The among-cow variation varied strongly between herds, but for a typical herd, if using reticuloruminal pH boluses to detect a predisposition to fermentation disorders while feeding a diet that is high in rapidly fermentable carbohydrates, it is recommended to use a minimum of nine boluses.

Impact of diet composition and temperature-humidity index on water and dry matter intake of high-yielding dairy cows.

The temperature-humidity index (THI) is widely used to characterize heat stress in dairy cattle. Diet composition is known to induce variation in metabolic-associated heat production. However, the relationships between THI and diet are poorly characterized with regard to performance and intake behaviour. Therefore, the objectives were to evaluate the impact of THI on water intake (WI), dry matter intake (DMI) and the frequency of drinking and feeding bouts in lactating dairy cows offered four dietary treatments: each contained 20% grass silage and additionally (i) 20% maize silage, 60% concentrate (M-HC); (ii) 60% maize silage, 20% concentrate (M-LC); (iii) 20% pressed beet pulp silage, 60% concentrate (BPS-HC); or (iv) 60% pressed beet pulp silage, 20% concentrate (BPS-LC) (DM basis). Individual WI and DMI were recorded from April to July 2013. Furthermore, dietary effects on milk production and reticular pH were estimated. Milk yield was lowest for M-LC, while energy-corrected milk was similar for all diets. Milk fat percentage was higher and milk protein amount lower for cows offered both LC diets. Reticular pH below 6.3, 6.0 and 5.8 lasted longest for BPS-LC. WI was higher for HC diets. However, the frequency of drinking bouts was not influenced by the ration. Lower DMI occurred for BPS-LC compared to M-LC. Frequency of feeding bouts was significantly higher for LC diets. THI was significantly related to WI, DMI as well as drinking and feeding bouts. Per increasing THI, WI increased slightly more for LC diets and DMI decreased more for HC diets. Frequency of drinking bouts increased slightly higher for BPS rations per rising THI, while the decrease in feeding bouts was highest for M-HC. In conclusion, TMR composition and moderate heat stress impacted WI and DMI of dairy cows, while both dietary energy density and ruminal filling might intensify the THI impact.

Reticulo-rumen mass, epithelium gene expression, and systemic biomarkers of metabolism and inflammation in Holstein dairy cows fed a high-energy diet.

Feeding a higher-energy diet by increasing cereal grains at the expense of forage during the last 3 to 4 wk prepartum is a traditional approach to help the rumen "adapt" to the traditional diets fed at the onset of lactation. Increasing grain/concentrate in the diet changes ruminal fermentation and in sheep and goats elicits marked changes in mRNA expression of immune-related genes in ruminal epithelium. Whether such changes at the epithelial and systemic levels occur in dairy cows when the dietary energy content increases at a fixed level of concentrate is unknown. Fourteen nonpregnant, nonlactating Holstein cows were fed a control lower-energy (CON, 1.30 Mcal/kg of dry matter) diet to meet 100% of estimated nutrient requirements for 3 wk, after which half of the cows were assigned to a higher-energy diet (OVE, 1.60 Mcal/kg of dry matter) and half of the cows continued on CON for 6 wk. Levels of forage and concentrate for CON and OVE were 80 and 79% and 20 and 21%, respectively. Plasma samples were collected 1 d before slaughter to examine biomarkers of metabolism, liver function, inflammation, and oxidative stress. The reticulo-rumen mass was recorded at slaughter, and samples of epithelium were harvested from all cows. The expression of 29 genes associated with tight junctions, immune function, and nutrient transport (volatile fatty acids, urea, and trace minerals) was examined. Overfeeding energy led to consistently greater dry matter intake over time, and lowered plasma concentrations of haptoglobin, paraoxonase, bilirubin, fatty acids, and myeloperoxidase (secreted by neutrophils). In contrast, OVE resulted in greater hydroxybutyrate and cholesterol concentrations. A greater reticulo-rumen mass in cows fed OVE did not alter genes associated with tight junctions (CDLN1, CDNL4, OCLN, TJP1), immune function (IL1B, IL10, NFKB1, TLR2, TLR4, TNF), oxidative stress (SOD1, SOD2), or most nutrient transporters. However, feeding OVE upregulated the acute-phase protein SAA3 by 3.5-fold and downregulated a volatile fatty acid transporter (SLC16A1) and a Fe and Cu transporter (SLC11A2). The lack of effect on mRNA expression along with lower plasma concentrations of inflammation biomarkers indicates that long-term intake of a higher-energy diet ad libitum was not detrimental to ruminal epithelium integrity. In that context, a protective function of SAA3 could be envisioned with a role in opsonizing gram-negative bacteria that produce endotoxins. The long-term control of volatile fatty acid absorption and trace minerals from the rumen in cows overfed energy does not seem to be controlled at the gene transcription level. The relevance of these findings to the nutritional management of pregnant dry cows merits further research.

Changes in reticulorumen content temperature and pH according to time of day and yearly seasons.

The monitoring of rumen content temperature can be useful for the evaluation of cow health condition and heat. The aim of this research was to evaluate the influence of the circadian rhythm (time of day) and season on reticulorumen acidity (pH) and temperatures (RT) in lactating dairy cows. The research was performed on ten 2nd - lactation, clinically healthy Lithuanian Black and White fresh dairy cows (up to 1 day after calving). The cows were milked twice daily at 05:00 and 17:00. The cows were kept in a loose housing system, and were fed a feed ration throughout the year at the same time, balanced according to their physiological needs. Cow feeding took place every day at 06:00 and 18:00. The pH and temperature of the contents of cow reticulorumens were measured using specific smaXtec boluses manufactured for animal care. The temperature starts rising 6 hours after the evening feeding and milking, whereas 1 hour after the morning milking, it starts decreasing. The lowest temperature observed in the springtime was 38.81±0.001, and the highest was in autumn 39.17±0.001. The pH starts decreasing 3 hours after the morning feed, whereas 4 hours after the evening feed, it starts increasing. The lowest pH was observed in the summertime - 5.99±0.001, and the highest was in autumn and springtime - 6.18±0.001. In conclusion the reticulorumen temperature in lactating cows was found to be influenced by the circadian rhythm and season. The acidity of the reticulorumen content changes similar to the temperature. The pH of the reticulorumen contents was also found to be influenced by the circadian rhythm and season.

Distribution of ki-67, alpha smooth muscle actin and vimentin in the reticulum and omasum of Baladi goat

Seven Baladi goats of both sexes (9 to 24 months old) were used to describe the distribution pattern of ki-67, alpha smooth muscle actin (áSMA) and vimentin (VIM) in the reticulum and omasum. This study was carried out using the avidin-biotin immunoperoxidase method. Ki-67 immunostaining was restricted to the basal cells layer in the epithelia of both the reticulum and omasum, suggesting the importance of ki-67 in epithelial cells proliferation and keratin biosynthesis. Immunostaining for áSMA was detected in smooth muscle cells in reticular folds, omasal lamiae and muscularis in both the reticulum and omasum, indicating the critical role of áSMA in muscular motility. The widespread distribution of VIM immunostainings in epithelia, fibroblasts in lamina propria and submucosa, and endothelia of blood vessels supports the importance of VIM as an intermediate filament protein. Detection of VIM in glial cells of enteric plexuses indicates its supportive role in the nervous control of both reticulum and omasum. Overall, this immunohistochemical study revealed non-significant differences in the expression of ki-67, áSMA, and VIM between the reticulum and omasum. This study thus verifies the important roles of ki-67, áSMA and VIM in the structure and function of the reticulum and omasum of Baladi goats

No disponible

Continuous measurement of reticuloruminal pH values in dairy cows during the transition period from barn to pasture feeding using an indwelling wireless data transmitting unit.

This study was performed to investigate the effect of the transition from barn feeding to pasture on the pattern of reticuloruminal pH values in 8 multiparous dairy cows. A indwelling wireless data transmitting system for pH measurement was given to 8 multiparous cows orally. Reticuloruminal pH values were measured every 600 s over a period of 42 days. After 7 days of barn feeding (period 1), all of the animals were pastured with increasing grazing times from 2 to 7 h/day over 7 days (period 2). From day 15 to day 21 (period 3), the cows spent 7 h/day on pasture. Beginning on day 22, the animals had 20 h/day access to pasture (day and night grazing). To study reticuloruminal adaptation to pasture feeding, the phase of day and night grazing was subdivided into another 3 weekly periods (periods 4-6). Despite a mild transition period from barn feeding to pasture, significant effects on reticuloruminal pH values were observed. During barn feeding, the mean reticuloruminal pH value for all of the cows was 6.44 ± 0.14, and the pH values decreased significantly (p < 0.001) during period 2 and 3 to 6.24 ± 0.17 and 6.21 ± 0.19 respectively. During periods 4, 5 and 6, the reticuloruminal pH values increased again (pH 6.25 ± 0.22; pH 6.31 ± 0.17; pH 6.37 ± 0.16). Our results showed that the animals had significantly lowered reticuloruminal pH during the periods of feed transition from barn to pasture feeding. Despite these significant changes, the decrease was not harmful, as indicated by data of feed intake and milk production.

Solute and particle retention in a small grazing antelope, the blackbuck (Antilope cervicapra).

Digesta retention patterns have been suggested to play a major role in ruminant diversification. Two major digestion types have been proposed, termed 'cattle-type' and 'moose-type', that broadly correspond to the feeding categories of grazers and intermediate feeders on the one, and browsers on the other hand. We measured and calculated the mean retention time (MRT) of a solute and a particle (<2 mm) marker in the gastrointestinal tract (GIT) and the reticulorumen (RR) of a small grazer, the Indian blackbuck (Antilope cervicapra, n=5, body mass of 26±4 kg) and an intermediate feeder, the nilgai (Boselaphus tragocamelus, n=5, body mass of 168±21 kg). MRT(solute) and MRT(particle) were 29±4.1 h and 60±6.6 h in blackbuck and 28±2.5 h and 54±8.9 h in the nilgai for the GIT, and 14±1.7 h, 45±5.0 h, 19±2.0 h and 45±8.4 h for the RR, respectively. With a selectivity factor (SF, the ratio of MRT(particle) to MRT(solute)) in the RR of 3.2±0.28 for blackbuck and 2.3±0.36 for nilgai, both species are clearly in the category of 'cattle-type' ruminants. In particular, the high SFRR of blackbuck, in spite of its small body size, is remarkable, and leads to specific predictions on the RR anatomy of this species (such as a particularly large omasum), which can be tested in further studies. The adaptive value of a high SFRR is mainly considered as an increase in microbial productivity in the RR.

Ultrasonographic assessment of reticuloruminal motility in 45 cows.

The goal of this study was to investigate the feasibility of ultrasonographic assessment of reticuloruminal motility in 45 healthy cows. The transducers of five ultrasound machines were connected to a digital video recorder and placed simultaneously at five sites on the left side of the cows to scan the reticulorumen (reticulum; ruminal atrium; dorsal sac of the rumen; left longitudinal groove; ruminal recess, caudodorsal and caudoventral blind sacs). The video streams from all five ultrasound machines were recorded synchronously with the same time line and displayed on a single monitor. Time 0 was defined as the start of a biphasic reticular contraction. The reticulum was visualised in all cows and had 11.0 ± 2.12 biphasic contractions in 9 min. The ruminal atrium was visualised in 40 (89%) cows and had 10.7 ± 2.10 contractions in 9 min, which started at the time point 5.0 ± 0.83 sec and lasted 7.0 ± 2.14 sec. Contractions of the dorsal sac of the rumen, visible in all cows, were visualised in 29 (64%) cows. There were 9.5 ± 1.8 contractions in 9 min that started at the time point 4.0 ± 0.85 sec and lasted 8.2 ± 1.04 sec. The left longitudinal groove was seen contracting in 39 (87%) cows. There were 10.2 ± 1.98 contractions in 9 min that started at the time point 4.1 ± 1.81 sec and lasted 7.8 ± 1.19 sec. Contractions of the ventral sac of the rumen (ruminal recess) were seen in 31 (69%) cows. There were 7.5 ± 2.59 contractions in 9 min that started at the time point 14.3 ± 4.30 sec. Contractions of the caudodorsal and caudoventral blind sacs were seen in 34 (76%) cows. There were 9.0 ± 2.75 (1.0 ± 0.31) contractions/min and 9.4 ± 2.09 (1.0 ± 0.23) contractions/min of the dorsal and ventral blind sacs, and they started at the time points 6.2 ± 1.32 sec and 21.3 ± 6.20 sec, respectively. Primary contraction cycles were seen in all cows and secondary cycles in 22 (49%) cows. The former were complete in 37 (82%) cows and incomplete in 8 (18%). There were 11.0 ± 2.12 primary and 4.5 ± 2.15 secondary cycles in 9 min, and the ratio between primary and secondary cycles averaged 2.4:1. Ultrasonography is suitable for the assessment of reticuloruminal motility

Digesta sampling sites and marker methods for estimation of ruminal outflow in bulls fed different proportions of corn silage or sugarcane.

The objective of this experiment was to assess ruminal outflow and apparent total-tract digestibility using digesta samples from 3 sites (reticulum, omasum, and abomasum) and 3 marker methods (single marker: indigestible NDF [iNDF; sample without separation]; double marker: iNDF + Co-EDTA [filtered sample]; and triple marker: iNDF + ytterbium [Yb] acetate + Co-EDTA [filtered and centrifuged]) in bulls fed corn silage and sugarcane-based diets. Eight crossbred (Holstein × Zebu) bulls (353 ± 37 kg of BW; 24 ± 1 mo of age) with ruminal and abomasal cannulas were randomly distributed into two 4 × 4 Latin squares that were balanced for residual effects. The following experimental diets were used: 1) 60% corn silage + 40% concentrate, 2) 40% corn silage + 60% concentrate, 3) 60% fresh sugarcane + 40% concentrate, and 4) 40% fresh sugarcane + 60% concentrate. Reticular, omasal, and abomasal digesta samples were collected at 9-h intervals over 3 d. At the end of the experiment, a composite sample was prepared for each bull, and these samples were subsequently assigned to the 3 marker methods. The concentrations of CP, NDF, and iNDF of reticular digesta differed (P < 0.01) from those of the omasum and abomasum. Use of omasal and abomasal samples led to similar estimates of ruminal outflow and ruminal digestibility for DM (P = 0.65), OM (P = 0.68), CP (P = 0.85), and NDF (P = 0.57). In contrast, the ruminal outflow of digesta based on reticular sampling appeared to be underestimated. We recommend sampling from the omasum because sampling from this region is less invasive than sampling from the abomasum. Although we did not observe differences in ruminal NDF digestibility among the different marker methods, we did observe that ruminal digestibility of CP was greater for the single marker method than for the double and triple marker methods; we therefore recommend the use of the double or triple marker method.

Effect of feeding fine maize particles on the reticular pH, milk yield and composition of dairy cows.

The particle size of cereal grains has been found to modulate the rate of passage from the rumen and the digestibility of starch and neutral detergent fibre (NDF), but few studies have examined its impact on reticular pH. The study aimed to evaluate the effect of feeding finely ground maize on the risk of ruminal acidosis, milk yield and composition. Twelve Holstein-Friesian cows were assigned to one of two experimental groups and fed according to a cross-over design. Diets were isoenergetic and isonitrogenous and were characterised by the same NDF and ADF, differing only in maize particle size. In the control diet (Ct), the maize meal was ground to 1.0 mm, whereas in the experimental diet, it was finely ground (Fg) to 0.5 mm. The pH and temperature of the reticulum were continuously measured in eight cows throughout the trial using indwelling sensors. Dry matter intake was higher in cows offered Fg diet than in Ct (19.0 vs. 20.3 kg/day; p = 0.067). However, milk yield (p = 0.855) and the 3.5% fat-corrected milk (FCM) (p = 0.724) did not show any differences between the diets. Casein (2.48 vs. 2.57%; p = 0.035) and crude protein (CP) (3.18 vs. 3.31%; p = 0.021) resulted higher in Fg. Similarly, starch digestibility increased in animals offered Fg diet versus Ct (0.94 vs. 0.98; p = 0.078). Among the reticular parameters, the Fg-fed cows spent a significantly higher time below the 5.5 pH threshold (15 vs. 61 min/day; p = 0.047) and had an average daily variation in reticular pH characterised by a lower nadir pH (5.95 vs. 5.72; p < 0.001) and a higher pH range (0.79 vs. 0.94; p = 0.003). In this study, grain particle size affected the risk of the onset of ruminal acidosis. Therefore, it should be carefully considered when formulating rations.

Short communication: Feeding linseed oil to dairy goats with competent reticular groove reflex greatly increases n-3 fatty acids in milk fat.

A crossover experiment was designed to compare the effects of 2 ways of feeding linseed oil on milk fat fatty acid (FA) composition. Ten lactating goats, trained to keep competent their inborn reticular groove reflex, received a daily dose of linseed oil (38 g/d) either with their solid (concentrate) feed (CON) or emulsified in skim milk and bottle-fed (BOT). Two groups of 5 goats received alternative and successively each of the treatments in two 15-d periods. α-Linolenic acid in milk fat rose up to 13.7% in the BOT versus 1.34% in the CON treatment. The n-6 to n-3 FA ratio was significantly reduced in goats receiving bottle-fed linseed oil (1.49 vs. 0.49). Contents of rumen biohydrogenation intermediates of dietary unsaturated FA were high in milk fat of goats under the CON treatment but low in those in the BOT treatment. These results point to a clear rumen bypass of the bottle-fed linseed oil. This strategy allows obtaining milk fat naturally very rich in n-3 FA and very low in trans FA. Translating this approach into practical farm conditions could enable farmers to produce milk enriched in specific FA.

Feed restriction reduces short-chain fatty acid absorption across the reticulorumen of beef cattle independent of diet.

The objective of this study was to evaluate the effects of the forage-to-concentrate ratio (F:C) of diets fed before and during short-term feed restriction (FR) on rumen fermentation, absorptive capacity of the reticulorumen, and apparent total tract digestibility. Twenty ovariectomized and ruminally cannulated Angus × Hereford heifers were blocked by BW and individually penned in box stalls (9 m(2)), having free access to water throughout the study. Heifers were randomly assigned to 1 of 2 dietary treatments, receiving either a high forage diet (HF; F:C of 92:8) or a moderate forage diet (MF; F:C of 60:40). Diets were fed ad libitum for 14 d before 5 d of baseline measurements (BASE) followed by 5 d of FR where heifers were restricted to 25% of ad libitum DMI relative to BASE. Dry matter intake was measured daily and ruminal pH was recorded every 2 min throughout the study. Ruminal fluid and blood samples were collected on d 3 of BASE and FR whereas short-chain fatty acid (SCFA) absorption was assessed in vivo using the isolated washed reticulorumen technique on d 5 of BASE and FR. Indigestible NDF was used as a marker to estimate apparent total tract digestibility. Diet × period interactions (P = 0.030 and 0.025) were detected for DMI and ruminal SCFA concentration, respectively. The interaction was the result of greater DMI and numerically greater SCFA concentration for MF than HF during BASE, with a reduction observed for both during FR, although treatment effects were no longer present. Period effects (BASE vs. FR) but not treatment effects (P > 0.05) were detected for mean ruminal pH (P < 0.001) and the total SCFA absorption rate (mmol/h; P = 0.038). During BASE, mean pH was reduced (6.4 vs. 6.9) and the SCFA absorption rate was greater relative to FR (674.5 vs. 554.8 mmol/h). Diet (P < 0.001) and period (P < 0.001) effects were detected for DM and OM digestibility with greater digestibility occurring for heifers fed MF than HF (70.5 vs. 63.3% for DM and 73.0 vs. 66% for OM) and greater digestibility during FR than BASE (69.5 vs. 64.3% for DM and 71.7 vs. 67.2% for OM). During FR, NDF digestibility was also greater than during BASE (P < 0.001; 62.4 vs. 55.8%). The effect of FR on serum NEFA differed by diet (diet × period, P < 0.001) with NEFA being greater for heifers fed HF than MF during FR (474.4 vs. 377.7 µEq/mL, respectively) with no differences observed between HF and MF during BASE. It can be concluded that severe short-term FR had a negative impact on ruminal SCFA absorption and energy balance and that altering the F:C of the diet does not mitigate these effects.

Influence of breed, milk production, season, and ambient temperature on dairy cow reticulorumen temperature.

Automatic monitoring of core body temperature in dairy cattle could be useful for identification of illness, heat stress, general physiological stress, and estrus. The SmartBolus (TenXSys Inc., Eagle, ID) system used a reticulorumen bolus to automatically record and transmit dairy cow temperatures. The objective of this research was to characterize the influence of milk yield (MY), time of day, breed, ambient temperature (AT), and season on reticulorumen temperatures (RT) in lactating dairy cows. Continuous RT and AT were collected by SmartBolus transponders every 15 min (96 records per d) from 93 cows (65 Holstein, 18 crossbred, and 10 Jersey) for 615 d. Mean (±SD) daily RT, AT, and MY were 40.14±0.32°C, 12.20±10.61°C, and 33.85±8.67 kg, respectively. The maximum and minimum RT were recorded at 2330 and 1000 h, respectively. Ambient temperature increased RT. Summer RT was significantly greater than spring, fall, or winter RT. The effect of MY on RT varied by breed, season, and AT. Crossbred RT was significantly lower than Holstein RT after adjusting for MY. Crossbred RT responded less to increasing AT than did Holstein RT, potentially indicating improved heat tolerance among these crossbred dairy cows. Reticulorumen temperature increased more dramatically for cows with greater milk yield as AT increased, demonstrating that high-producing cows are more susceptible to heat stress than low-producing cows. These results could be useful in interpretation of automatic temperature system data, heat stress management, and genetic selection of heat-tolerant cows.

Using temperature-sensing reticular boluses to aid in the detection of production diseases in dairy cows.

The objective of this study was to investigate associations between increases in reticular temperature (RT) in dairy cows and the diagnosis of metritis, mastitis, lameness, and pneumonia by dairy personnel. A prospective case-control study was conducted on a 2,175-cow dairy operation in Colorado from May 2010 to April 2011. Each cow received an orally administered temperature sensing reticular bolus after parturition and RT measurements were recorded 3 times per day as lactating cows exited the milking parlor. A cow was identified as having an increased RT when a deviation of 0.8°C above baseline (average of readings of previous 10d) was recorded by the TempTrack software (DVM Systems, LLC, Greeley, CO). During the same study period, dairy personnel without access to RT data recorded health events and classified them according to clinical signs observed. A total of 201 health events (cases) were included in the data analysis. Cows with clinical mastitis and pneumonia had significantly higher odds (6.7 and 7.5 times higher, respectively) of having an increased RT of 0.8°C above their baseline within 4d preceding diagnosis when compared with control cows. Specificity and sensitivity for an increase of 0.8°C above baseline RT within 4d of disease diagnosis was 76.85 and 66.97% for mastitis, and 69.23 and 76.92% for pneumonia, respectively. No significant difference in RT was found for cows diagnosed with lameness or metritis. Results of this study suggest that RT monitoring can be a useful tool in the early detection of mastitis and pneumonia in dairy cows.