Relationships between reticular contractions and digesta passage in steers consuming alfalfa hay and barley straw combinations ad libitum

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.

Alfalfa hay improves nursing performance of Awassi ewes and performance of growing lambs when used as a source of forage compared with wheat straw

Two experiments were conducted to evaluate the effect of replacing wheat straw (WS) with alfalfa hay (ALF) in diets fed to Awassi lactating ewes (exp. 1) and weaned lambs (exp. 2). In each experiment, sheep were fed 1 of 3 treatment diets containing WS only, WS and ALF mix (50:50; WS-ALF), or ALF only as the forage sources. In exp. 1, 33 lactating Awassi ewes were assigned randomly to treatment diets (11 ewes/diet) and fed ad libitum for 56 days. Intakes of dry matter (DM) and crude protein (CP) were greater (P = 0.001) in WS-ALF and ALF diets than WS diet. Ewe weight-of-lamb weaned, and nursing-lamb average daily gain (ADG) was greatest for ALF, intermediate for WS-ALF, and least for WS treatment groups (P < 0.0001). Milk production (kg/day) tended to be greater (P = 0.07) in ALF diets compared with WS diets. Milk protein, total solids, and lactose production (g/day) were greater (P < 0.04) in ewes fed ALF and WS-ALF diets compared with WS diet. In exp. 2, 27 newly weaned lambs were randomly assigned to treatment diets (9 lambs/treatment) and fed ad libitum for 70 days. Intake and digestibility of DM were greater (P < 0.05) in lambs fed the ALF diet compared with the WS diet. Lamb total gain and ADG were greater (P < 0.01) for lambs fed WS-ALF and ALF diets compared with WS diet. Replacement of wheat straw with alfalfa hay improved most of performance and productivity measured variables of Awassi lactating ewes and growing lambs.

Effects of the dietary nonfiber carbohydrate content on lactation performance, rumen fermentation, and nitrogen utilization in mid-lactation dairy cows receiving corn stover

Background

Corn stover (CS) is an abundant source of feed for livestock in China. However, it is low in nutritional value that we have been seeking technologies to improve. Previous studies show that non-fiber carbohydrate (NFC) might limit the utilization of a CS diet by lactating dairy cows. Thus, this study was conducted to investigate the lactation performance and rumen fermentation characteristics in lactating cows consuming CS with two contents of NFC compared to an alfalfa hay-containing diet. Twelve Holstein cows were used in a replicated 3 × 3 Latin square design with three dietary treatments: (1) low-NFC diet (NFC = 35.6%, L-NFC), (2) high-NFC diet (NFC = 40.1%, H-NFC), and (3) alfalfa hay diet (NFC = 38.9%, AH).

Results

Intake of DM was lower for cows fed H-NFC compared to L-NFC and AH, while the milk yield was higher in AH than in H-NFC and L-NFC (P < 0.01). The feed efficiency (milk yield/DM intake, 1.15 vs. 1.08, P < 0.01) were greater for cows fed H-NFC than L-NFC. The contents of milk protein and lactose were not different among the groups (P > 0.11), but milk fat content was higher for cows fed H-NFC and L-NFC compared to AH (P < 0.01). The rumen ammonia nitrogen concentration and the concentrations of urea nitrogen in blood and milk were lower for cows fed H-NFC and AH compared to L-NFC (P < 0.05). The concentrations of rumen propionate and total volatile fatty acids were different among groups (P < 0.05) with higher concentration for cows fed AH compared to H-NFC and L-NFC, and acetate concentration tended to be different among groups (P = 0.06).

Conclusions

From the results obtained in this study, it was inferred that the increased NFC content in a diet containing corn stover can improve the feed efficiency and benefit the nitrogen conversion.

Quantifying body water kinetics and fecal and urinary water output from lactating Holstein dairy cows

Reliable estimates of fresh manure water output from dairy cows help to improve storage design, enhance efficiency of land application, quantify the water footprint, and predict nutrient transformations during manure storage. The objective of the study was to construct a mechanistic, dynamic, and deterministic mathematical model to quantify urinary and fecal water outputs (kg/d) from individual lactating dairy cows. The model contained 4 body water pools: reticulorumen (QRR), post-reticulorumen (QPR), extracellular (QEC), and intracellular (QIC). Dry matter (DM) intake, dietary forage, DM, crude protein, acid detergent fiber and ash contents, milk yield, and milk fat and protein contents, days in milk, and body weight were input variables to the model. A set of linear equations was constructed to determine drinking, feed, and saliva water inputs to QRR and fractional water passage from QRR to QPR. Water transfer via the rumen wall was subjected to changes in QEC and total water input to QRR. Post-reticulorumen water passage was adjusted for DM intake. Metabolic water production and respiratory cutaneous water losses were estimated with functions of heat production in the model. Water loss in urine was driven by absorbed N left after being removed via milk. Model parameters were estimated simultaneously using observed fecal and urinary water output data from lactating Holstein cows (n=670). The model was evaluated with data that were not used for model development and optimization (n=377). The observations in both data sets were related to thermoneutral conditions. The model predicted drinking water intake, fecal, urinary, and total fresh manure water output with root mean square prediction errors as a percentage of average values of 18.1, 15.6, 30.6, and 14.6%, respectively. In all cases, >97% of the prediction error was due to random variability of data. The model can also be used to determine saliva production, heat and metabolic water production, respiratory cutaneous water losses, and size of major body water pools in lactating Holstein cows under thermoneutral conditions.

Ultrasonographic evaluation of reticular motility during rest, eating, rumination and stress in 30 healthy cows

A 3.5 MHz linear transducer was used to assess the motility of the reticulum in 30 healthy, standing, non-sedated cows while they were at rest, eating, ruminating and under stress. The ultrasonographic examinations were made over periods of nine minutes and video recorded for analysis. The reticulum contracted in a biphasic pattern while the cows were resting, eating or stressed. The first contraction was incomplete and was followed by a period of incomplete relaxation. A complete second contraction occurred immediately afterwards, followed by an interval of complete relaxation and the return of the organ to its original position. When the cows were ruminating, a regurgitation contraction, which was incomplete, occurred immediately before the biphasic contraction. The number of reticular contractions in a nine-minute period was largest when the cows were eating (13.9 contractions, or approximately 1.5 per minute) and smallest when they were stressed (9.3 contractions, or approximately 1 per minute). The duration of the first reticular contraction was shortest during rumination (2.4 seconds) and longest when the cows were eating (3.0 seconds). The interval between two biphasic contractions was shortest when the cows were eating (31.6 seconds) and longest when they were stressed (53.8 seconds).

Development of a Mechanistic Model to Represent the Dynamics of Liquid Flow Out of the Rumen and to Predict the Rate of Passage of Liquid in Dairy Cattle

A mechanistic and dynamic model was developed to represent the physiological aspects of liquid dynamics in the rumen and to quantitatively predict liquid flow out of the reticulorumen (RR). The model is composed of 2 inflows (water consumption and salivary secretion), one outflow (liquid flow through the reticulo-omasal orifice (ROO), and one in-and-out flow (liquid flux through the rumen wall). We assumed that liquid flow through the ROO was coordinated with the primary reticular contraction, which is characterized by its frequency, duration, and amplitude during eating, ruminating, and resting. A database was developed to predict each component of the model. A random coefficients model was used with studies as a random variable to identify significant variables. Parameters were estimated using the same procedure only if a random study effect was significant. The input variables for the model were dry matter intake, body weight, dietary dry matter, concentrate content in the diet, time spent eating, and time spent ruminating. Total water consumption (kg/d) was estimated as 4.893 x dry matter intake (kg/d), and 20% of the water consumed by drinking was assumed to bypass the RR. The salivary secretion rate was estimated to be 210 g/min during chewing. During ruminating, however, the salivation rate was assumed to be adjusted for the proportion of liquid in the rumen. Resting salivation was exponentially related to dry matter intake. Liquid efflux through the rumen wall was assumed to be the mean value in the database (4.6 kg/h). The liquid outflow rate (kg/h) was assumed to be a product of the frequency of the ROO opening, its duration per opening, and the amount of liquid passed per opening. Simulations of our model suggest that the ROO may open longer for each contraction cycle than had been previously reported (about 3 s) and that it is affected by dry matter intake, body weight, and total digesta in the rumen. When compared with 28 observations in 7 experiments, the model accounted for 40, 70, and 90% of the variation, with root mean square prediction errors of 9.25 kg, 1.84 kg/h, and 0.013 h(-1) for liquid content in the rumen, liquid outflow rate, and fractional rate of liquid passage, respectively. A sensitivity analysis showed that dry matter intake, followed by body weight and time spent eating, were the most important input variables for predicting the dynamics of liquid flow from the rumen. We conclude that this model can be used to understand the factors that affect the dynamics of liquid flow out of the rumen and to predict the fractional rate of liquid passage from the RR in dairy cattle.

Biogenic amines in silage, apparent postruminal passage, and the relationship between biogenic amines and digestive function and intake by steers

A 4 x 4 Latin square experiment was conducted to examine abomasal passage of biogenic amines in steers fed silage and their related effects on intake, digestibility, and digestive function. Thirty percent of the dry matter (DM) in the diets consisted of alfalfa forage, which was fed as either hay or silage. The DM from alfalfa silage DM was substituted at 0, 33, 67, and 100% for DM from alfalfa hay and was fed to four ruminally and abomasally cannulated steers. The roughage component of the diet constituted 50% of the DM and consisted of 60% alfalfa silage or hay and 40% tropical corn silage. The concentrate was composed mainly of ground corn. The concentrations of putrescine and cadaverine in abomasal digesta increased as alfalfa silage in the diet increased. Abomasal recovery of biogenic amines, a product of their concentration in abomasal digesta and the passage of DM through the abomasum, was negatively correlated with intake. Abomasal recovery of most amines was 5 to 20% of intake. Abomasal recovery of cadaverine was correlated with depressed intake. Total DM intake was reduced 8.3 to 25.8% as the proportion of alfalfa silage in the diet increased. Frequency of reticular contractions, intake, ruminal DM digestibility, ruminal outflow, volatile fatty acids, and total tract DM digestibility decreased in steers fed diets that contained more alfalfa silage. Ruminal fluid pH and NH3 concentration increased in steers fed more alfalfa silage; however, mass and the DM percentage of ruminal contents decreased linearly. Postprandial insulin concentrations were quadratically related to the proportion of alfalfa hay or silage in the diet. Intraruminal metabolism of biogenic amines is extensive based on the relatively low quantities recovered in abomasal digesta; however, the amounts recovered in abomasal digesta were related to intake depression and associated physiological effects.

Forage source alters nutrient supply to the intestine without influencing milk yield

Eight Holstein cows in early lactation and fitted with ruminal and duodenal cannulas were used in a 4 x 4 Latin square design experiment to determine the influence of forage source on microbial digestion in the rumen and nutrient supply to the intestine and to determine relationships between DMI, ruminal fill, and NDF content of silage. Cows were fed a TMR formulated to contain a 50:50 concentrate:forage ratio. A significant negative correlation was found between dietary NDF concentration (range 32.2 to 37.9%) and DMI (16.7 to 19.6 kg/d). In addition to forage NDF concentration, the lower DMI of cows fed oat or triticale silage (16.7 and 17.2 kg/d, respectively) relative to that of cows fed barley or alfalfa silage (18.6 and 19.6 kg/d, respectively) might reflect a lower true rate of NDF digestion (range 2.39 to 4.09%/h), higher ruminal turnover time (12.9 to 17.1 h), and lower rate of NDF intake (3.31 to 3.96%/h). However, differences in ruminal bacterial yield, ruminal metabolites, and nutrient supply to the intestine associated with different silages had no major effect on dairy cow performance. We concluded that the dairy cow can maintain similar milk yield despite marked differences in the type of end products arising from carbohydrate and protein digestion.