Effect of particle size of forage and rumen cannulation upon chewing activity and laterality in dairy cows

Validation of automatic monitoring of feeding behaviours in sheep and goats

Monitoring the feeding and ruminating behaviour of ruminants can be used to assess their health and welfare. The MSR-jaw movement recording system (JAM-R) can automatically record the jaw movements of ruminants. The associated software Viewer2 was developed to classify these recordings in adult cattle and calculate the duration and number of mastications of feeding and ruminating. The purpose of this study was to evaluate the performance of Viewer2 in classifying the behaviour of sheep and goats and assessing their feeding and ruminating. The feeding and ruminating behaviour of ten sheep and ten goats on pasture (observed live) and of five sheep and five goats in the barn (observed by video) were compared with Viewer2 behaviour classifications. To assess the technical and welfare issues of the JAM-R, its application was tested in a feeding experiment with 24 h monitoring of the feeding behaviours of 24 sheep and 24 goats. Viewer2 worked equally well on both species. The mean (95% confidence interval) performance of Viewer2 was at a good level for feeding (accuracy: 0.8-1.0; sensitivity: 0.9-1.0; specificity: 0.6-0.9; precision: 0.7-0.9) and ruminating (accuracy: 0.8-0.9; sensitivity: 0.6-0.8; specificity: 0.8-1.0; precision: 0.9-1.0) compared with human observations, with minor differences between the conditions on pasture and in the barn. The performance improved when recording frequency was increased from 10 Hz to 20 Hz. Applying the JAM-R in a feeding experiment, 71% of the recordings executed were defined as technically error-free and produced plausible values for feeding behaviours. In conclusion, according to the values of accuracy, sensitivity, specificity and precision, the presented JAM-R system with Viewer2 is a reliable and applicable technology for automatic recording of feeding and ruminating behaviour of sheep and goats on pasture and in the barn.

Rumination and Activity Patterns in Angus and Angus-Cross Beef Calves: Influences of Sex, Breed, and Backgrounding Diet

The objectives of this study were to evaluate the influences of sex, breed, and backgrounding diet on rumination and activity patterns in Angus and Angus-cross beef calves; and the daily variations in rumination and activity in Angus and Angus-cross beef calves under different backgrounding systems. A total of 62 freshly weaned calves were vaccinated and randomly stratified by sex (heifers and steers), breed (Angus and Angus × Simmental cross), and assigned randomly to 3 backgrounding treatments for 55 days. The peak values for rumination and activity in heifers, steers, Angus, and Angus × Simmental cross occurred during the dark and light phases of the dark/light cycle, respectively. Beef calves backgrounded on cover crops had higher (p < 0.05) rumination (45.33 ± 1.57 min) compared with calves backgrounded on a perennial pasture (43.96 ± 1.47 min) diet. Similarly, drylot calves (24.16 ± 0.68 min) had higher (p < 0.05) activity compared to perennial pasture (23.49 ± 0.72 min). The results showed that sex and breed did not influence rumination and activity of Angus and Angus-cross beef calves during the study period. We concluded that the time of the day and backgrounding diet influenced rumination and activity patterns of Angus and Angus-cross beef calves.

The Value of ‘Cow Signs’ in the Assessment of the Quality of Nutrition on Dairy Farms

The aim of this review is to provide dairy farm advisors, consultants, nutritionists, practitioners, and their dairy farmer clients with an additional toolkit that can be used in the assessment of the quality of their dairy cattle nutrition. Cow signs are behavioral, physiological, and management parameters that can be observed and measured. They are detected by examining and observing the cattle. Other physiological parameters such as fecal scoring, rumen fill, and body condition scoring are also included in ‘cow signs’. The assessment should be both qualitative and quantitative; for example, is the cattle individual lame and what is the severity of lameness. The ‘diagnosis’ of a problem should be based on establishing a farm profile of ‘cow signs’ and other relevant information. Information gathered through assessment of cow signs should be used as an advisory tool to assist and improve decision making. Cow signs can be used as part of an investigation and or farm audit.

Effect of dietary protein level and corn processing on behavior activity of high producing dairy cows

The objective of this experiment was to evaluate the effects of corn processing and protein level on the feeding, lying, and post milking standing (PMS) behavior in high producing cows. Eight Holstein cows were randomly assigned to diets containing either finely ground (FGC) or steam flaked (SFC) corn based on either low (LP) or high (HP) protein content. Cows receiving LP had lower milk yield than cows receiving HP with similar DMI. Moreover, FGC-fed cows had higher DMI than SFC-fed cows with similar milk yields. Eating and rumination time tended to be lower and chewing time was lower in HP-fed cows than LP-fed cows. Cows fed SFC tended to have higher laying rumination interval and lower lying rumination bouts than cows fed FGC. Total and average PMS were lower in cows fed HP than LP. Cows fed LP had higher chewing activity in the daytime than cows fed HP. Our results suggested that the protein level and corn processing affect the standing and lying behavior of high producing dairy cows, although, this effect is marginal. Results also indicated that probably any change in the diet that increases the rumination and eating times could also improve the PMSThe objective of this experiment was to evaluate the effects of corn processing and protein level on the feeding, lying, and post milking standing (PMS) behavior in high producing cows. Eight Holstein cows were randomly assigned to diets containing either finely ground (FGC) or steam flaked (SFC) corn based on either low (LP) or high (HP) protein content. Cows receiving LP had lower milk yield than cows receiving HP with similar DMI. Moreover, FGC-fed cows had higher DMI than SFC-fed cows with similar milk yields. Eating and rumination time tended to be lower and chewing time was lower in HP-fed cows than LP-fed cows. Cows fed SFC tended to have higher laying rumination interval and lower lying rumination bouts than cows fed FGC. Total and average PMS were lower in cows fed HP than LP. Cows fed LP had higher chewing activity in the daytime than cows fed HP. Our results suggested that the protein level and corn processing affect the standing and lying behavior of high producing dairy cows, although, this effect is marginal. Results also indicated that probably any change in the diet that increases the rumination and eating times could also improve the PMS

The Effect of Frequency of Fresh Pasture Allocation on the Feeding Behaviour of High Production Dairy Cows

Simple Summary

In pasture based systems dairy cows spend more than 50% of their time grazing and ruminating, thus these behaviours require a lot of time and energy. Understanding the impact of management factors such as pasture allocation frequency on animal feeding behaviour will assist with the development of systems that support natural and efficient animal feeding behaviour. The aim of this study was to investigate the effect of frequency of fresh pasture allocation, three treatments offering fresh pasture every 12, 24 or 36 hours on the grazing and ruminating behaviours of high-yielding dairy cows. Animals displayed diurnal feeding patterns, irrespective of treatment, concentrating the majority of their grazing activity during the day (90%) and their ruminating activity during the night (73%). Peak grazing activity coincided with fresh pasture allocation in the 12 h and 24 h treatments. However, in the 36 h treatment peak grazing activity did not correspond with the allocation of fresh pasture and grazing was more evenly distributed over each 24 h period, indicating the animals’ inability to anticipate feed. Increased competition for resources in the 12 h treatment likely resulted in the greater grazing and ruminating times exhibited by primiparous animals, indicating greater overall energy expenditure on feeding behaviour.

Abstract

For ruminants, grazing and ruminating activities are essential in nutrient capture and ultimately animal performance however these activities can demand significant time and energy. This study evaluated the effect of three different pasture allocation frequencies (PAF’s; 12, 24 and 36 h) on the feeding behaviour of grazing dairy cows. Eighty-seven spring calving dairy cows were divided into three treatments. Animals were rotationally grazed with fixed paddock sizes of 0.14 ha, 0.28 ha and 0.42 ha paddocks for the 12 h, 24 h and 36 h treatments, respectively. Animals (14 per treatment) were fitted with behaviour halters that monitored feeding activity. Diurnal feeding patterns were evident for all animals irrespective of PAF, concentrating the majority of grazing during daytime (90%) and ruminating activity during night (73%). Treatment significantly affected feeding behavior patterns. Peak grazing activity coincided with fresh pasture allocation in the 12 h and 24 h treatments. In the 36 h treatment, grazing was more evenly distributed over each 24 h period with peak grazing activity witnessed daily between 17:00 and 19:00 regardless of fresh pasture allocation, suggesting lack of anticipation of fresh feed delivery. In the 12 h treatment primiparous animals exhibited greater grazing and ruminating activity relative to multiparous animals in the 12 h treatment highlighting the impact of competition for resources within each feed on lower dominance animals.

From Science to Practice: A Review of Laterality Research on Ungulate Livestock

In functional laterality research, most ungulate livestock species have until recently been mainly overlooked. However, there are many scientific and practical benefits of studying laterality in ungulate livestock. As social, precocial and domestic species, they may offer insight into the mechanisms involved in the ontogeny and phylogeny of functional laterality and help to better understand the role of laterality in animal welfare. Until now, most studies on ungulate livestock have focused on motor laterality, but interest in other lateralized functions, e.g., cognition and emotions, is growing. Increasingly more studies are also focused on associations with age, sex, personality, health, stress, production and performance. Although the full potential of research on laterality in ungulate livestock is not yet exploited, findings have already shed new light on central issues in cognitive and emotional processing and laid the basis for potentially useful applications in future practice, e.g., stress reduction during human-animal interactions and improved assessments of health, production and welfare. Future research would benefit from further integration of basic laterality methodology (e.g., testing for individual preferences) and applied ethological approaches (e.g., established emotionality tests), which would not only improve our understanding of functional laterality but also benefit the assessment of animal welfare.

Pelleted-hay alfalfa feed increases sheep wether weight gain and rumen bacterial richness over loose-hay alfalfa feed

Diet composed of smaller particles can improve feed intake, digestibility, and animal growth or health, but in ruminant species can reduce rumination and buffering-the loss of which may inhibit fermentation and digestibility. However, the explicit effect of particle size on the rumen microbiota remains untested, despite their crucial role in digestion. We evaluated the effects of reduced particle size on rumen microbiota by feeding long-stem (loose) alfalfa hay compared to a ground and pelleted version of the same alfalfa in yearling sheep wethers during a two-week experimental period. In situ digestibility of the pelleted diet was greater at 48 h compared with loose hay; however, distribution of residual fecal particle sizes in sheep did not differ between the dietary treatments at any time point (day 7 or 14). Both average daily gain and feed efficiency were greater for the wethers consuming the pelleted diet. Observed bacterial richness was very low at the end of the adaptation period and increased over the course of the study, suggesting the rumen bacterial community was still in flux after two weeks of adaptation. The pelleted-hay diet group had a greater increase in bacterial richness, including common fibrolytic rumen inhabitants. The pelleted diet was positively associated with several Succiniclasticum, a Prevotella, and uncultured taxa in the Ruminococcaceae and Rickenellaceae families and Bacteroidales order. Pelleting an alfalfa hay diet for sheep does shift the rumen microbiome, though the interplay of diet particle size, retention and gastrointestinal transit time, microbial fermentative and hydrolytic activity, and host growth or health is still largely unexplored.

Effects of a Change from an Indoor-Based Total Mixed Ration to a Rotational Pasture System Combined With a Moderate Concentrate Feed Supply on Rumen Fermentation of Dairy Cows

Simple Summary

In temperate climate zones, cows are in spring traditionally transitioned from a silage and concentrate- ration to a pasture-based ration. This transition requires complex nutritional and metabolic adaptions for the cow, resulting in a lower feed intake with consequences on energy metabolism. Normally concentrate feed is supplied to support the cows after transition to pasture. Depending on weather influences and growing stage, grass contains high amounts of fast fermentable carbohydrates and low amounts of physical effective fiber. In a previous trial, pasture feeding combined with low amounts of concentrate supply did not prevent an energy shortage after transition to pasture but led to changes in ruminal fermentation patterns indicating a possible risk for rumen health. However, the impact of ration change has not been extensively researched so far when moderate concentrate feed was supplied moderately in order to prevent an energy deficiency. To investigate the influences different rumen variables were documented, using continuous pH measuring devices and weekly diurnal fermentation assessments in rumen fistulated animals. Influence on rumen epithelial morphology was measured by the collection of rumen papillae biopsies and subsequent surface area, as well as histopathological analyses. With the help of this data, a greater understanding of the adaption period of the animals during transition from confinement to pasture is made possible.

Abstract

In spring, transition from a total mixed ration (TMR) to pasture requires rumen adaptions for the cow. It had been shown that transition period does not necessarily mean an increased risk for subacute ruminal acidosis (SARA). After adaption to pasture, however, supplying low amounts of concentrate did indicate increased risk, but caused no adverse effects on rumen morphology and absorption capacity. The present study aimed to investigate the effect of transition, and how a supply of 4.5 kg dry matter concentrate·cow⁻¹·day⁻¹ during fulltime grazing influenced different rumen parameters. During a 12-week trial eleven rumen-cannulated dairy cows were observed during transition from confinement to pasture (PG; n = 6) and compared to cows fed TMR indoors (CG; n = 5). The CG stayed on a TMR based ration (35% corn silage, 35% grass silage, 30% concentrate; dry matter basis), whereas the PG slowly switched to a pasture-based ration (week 0 and 1 = TMR, week 2 = TMR and 3 h pasture·day⁻¹, week 3 and 4 = TMR and 12 h pasture·day⁻¹, and week 5 to 11 = pasture combined with 4.5 kg DM concentrate·cow⁻¹·day⁻¹). Papillae surface area decreased during transition and increased again during fulltime grazing, while the fractional absorption rate of volatile fatty acids (VFA) was not influenced. This suggests only a limited effect of papillae surface area on VFA absorption rate. Feeding changes resulted in different fermentation profiles of VFA. Changing ratio of starch to sugar during transition to fulltime grazing plus concentrate supply did not lead to lower rumen pH. In conclusion, the concentrate supply combined with high fermentable grass during fulltime grazing increased papillae surface area but did not affect absorption rate or rumen pH, so that risk for SARA was not increased.

Invited review: Current perspectives on eating and rumination activity in dairy cows

Many early studies laid the foundation for our understanding of the mechanics of chewing, the physiological role of chewing for the cow, and how chewing behavior is affected by dietary characteristics. However, the dairy cow has changed significantly over the past decades, as have the types of diets fed and the production systems used. The plethora of literature published in recent years provides new insights on eating and ruminating activity of dairy cows. Lactating dairy cows spend about 4.5 h/d eating (range: 2.4-8.5 h/d) and 7 h/d ruminating (range: 2.5-10.5 h/d), with a maximum total chewing time of 16 h/d. Chewing time is affected by many factors, most importantly whether access to feed is restricted, intake of neutral detergent fiber from forages, and mean particle size of the diet. Feed restriction and long particles (≥19 mm) have a greater effect on eating time, whereas intake of forage neutral detergent fiber and medium particles (4-19 mm) affects rumination time. It is well entrenched in the literature that promoting chewing increases salivary secretion of dairy cows, which helps reduce the risk of acidosis. However, the net effect of a change in chewing time on rumen buffing is likely rather small; therefore, acidosis prevention strategies need to be broad. Damage to plant tissues during mastication creates sites that provide access to fungi, adhesion of bacteria, and formation of biofilms that progressively degrade carbohydrates. Rumination and eating are the main ways in which feed is reduced in particle size. Contractions of the rumen increase during eating and ruminating activity and help move small particles to the escapable pool and into the omasum. Use of recently developed low-cost sensors that monitor chewing activity of dairy cows in commercial facilities can provide information that is helpful in management decisions, especially when combined with other criteria. Although accuracy and precision can be somewhat variable depending on sensor and conditions of use, relative changes in cow behavior, such as a marked decrease in rumination time of a cow or sustained low rumination time compared with a contemporary group of cows, can be used to help detect estrus, parturition, and some illnesses. This review provides a comprehensive understanding of the dietary, animal, and management factors that affect eating and ruminating behavior in dairy cows and presents an overview of the physiological importance of chewing with emphasis on recent developments and practical implications for feeding and managing the modern housed dairy cow.

The Effect of Hock Injury Laterality and Lameness on Lying Behaviors and Lying Laterality in Holstein Dairy Cows

Simple Summary

Dairy cattle may experience discomfort in a myriad of ways throughout their life cycle, particularly when sustaining hock injuries or suboptimal locomotion. Lactating dairy cattle divide their lying time equally between left and right sides; however, discomfort experienced during pregnancy or following cannulation can cause a shift in the normal lying laterality. The objective of this study was to determine the effect of hock injuries and lameness on the lying behaviors of dairy cattle, particularly lying laterality. Lying laterality did not differ from the expected 50% (left side lying time) in cattle with hock injuries, lameness, or both. The current results suggest that lying laterality does not differ between varying levels of hock injury or lameness severity. Going forward, further research could determine if lying laterality shifts over the course of the animal developing a hock injury or lameness.

Abstract

Lactating dairy cattle divide their lying equally between their left side and their right side. However, discomfort, such as pregnancy and cannulation, can cause a cow to shift lying side preference. The objective of this study was to determine the effect of lameness and hock injuries on lying behaviors, particularly lying laterality, of lactating dairy cows. Cows from four commercial farms in eastern Croatia that had lying behavior data, health score data, and production records were used in the study. Health scores including hock injuries and locomotion were collected once per cow. Severely lame cows had greater daily lying time compared to sound cows and moderately lame cows. Overall, cows spent 51.3 ± 1.2% of their daily lying time on the left side. Maximum hock score, locomotion score, hock injury laterality, or parity did not result in lying laterality differing from 50%.

Effects of a completely pelleted diet on growth performance in Holstein heifers

Forage neutral detergent fiber (NDF) content and particle size are important factors that affect rumen function. The aim of the current study was to evaluate the effects on rumen health, NDF digestibility, and animal performance of pelleting a forage-based diet. Eight Holstein heifers (age 336±30d, body weight 346±35kg) were randomly assigned to a repeated crossover design. Animals were housed in tie-stalls and fed for ad libitum intake. The study included 4 periods of 3 wk, the first 2 wk for adaptation to the diet and the last wk for data collection. Diets had the same ingredients but had a different physical form: total mixed ration (TMR) and pellet (diameter=8mm). The physically effective NDF (peNDF) differed between the 2 treatments (39.8 and 11.8% of NDF in the TMR and pellet diets, respectively). During the trial, dry matter intake (DMI), water intake, rumination time, rumen temperature, and pH were evaluated daily. Fecal samples were collected in wk3 of each period to determine total-tract digestibility of the potential digestible (pd)NDF. Average daily gain and feed conversion ratio were calculated at the end of each period. With the pellet diet, DMI, DMI/body weight, and water consumption were higher. We observed no significant difference in average daily gain or feed conversion ratio. Rumination time was lower for the pellet diet than for the TMR diet (241 vs. 507min/d, respectively). Diet had no effect on rumen temperature or rumen pH. The total-tract digestibility of the pdNDF was greater with the TMR diet than with the pellet diet (90.25 vs. 86.82% pdNDF, respectively). The results of the current study suggest that a complete-feed pellet diet was well accepted by the animals, as demonstrated by higher DMI. Rumination time was reduced with the pellet diet, but rumen pH was not different. The pdNDF digestibility was high for both diets, but significantly higher for the TMR diet. Given that animal performance was similar between the 2 diets, although they differed with respect to DMI and fiber digestion, we hypothesize that the 2 diets had different retention times, related to their physical form. A complete-feed pellet diet formulated to provide a sufficient level of NDF from forages could be fed to growing ruminants without apparent negative effects on rumen health and animal productivity, at least for a short period. More research over a longer growing period is needed before recommending this feeding strategy for growing heifers.

Methodology for quantifying the behavioral activity of dairy cows in freestall barns

The objectives of this study were to 1) evaluate the validity of automated monitoring systems as assessment method for the behavioral activity of dairy cows compared with video recording, and 2) determine the sampling intervals required to obtain reliable estimates of the daily behavior. To determine lying, standing, and walking, 12 cows were equipped with automatic recording devices (IceTag = 12 cows, HOBO Pendant G = 5 cows), and their behavior was simultaneously recorded using a video recording system. The correspondence between the IceTag, HOBO logger, and video recording data was analyzed using 2 × 2 contingency tables, and we determined the sensitivity, specificity, and predictive value (positive and negative). Both types of loggers demonstrated high sensitivity (Sen ≥ 0.961) and specificity (Sp ≥ 0.951) for lying and standing behaviors with predictive values near 1.00. The HOBO logger can accurately describe the laterality of lying behavior, whereas the IceTag device inadequately recorded walking, with probability predictive values ≤ 0.303. Daily behaviors of the dairy cows were compared for 10 different sampling intervals (1 s, and 1, 2, 3, 4, 5, 10, 15, 30, and 60 min) collected by the IceTag, using linear regression. A strong relationship (R(2) ≥ 0.978) was found between the total lying times from data on a per-second basis and estimates obtained by 1, 2, 3, 4, 5, 10, and 15 min sampling intervals. The sampling intervals of 1 and 2 min were comparable for all aspects of lying behavior (R(2) ≥ 0.813; P > 0.05 for slope = 1, intercept = 0). Long sampling intervals (30 and 60 min) showed positive relationship for estimating time spent lying and standing (R(2) ≥ 0.774), but were inappropriate for predicting these behaviors, because they lacked accuracy and precision. Both the IceTag and HOBO logger accurately measured all aspects of lying and standing behavior. Reliable estimates of lying and standing time can be generated using relatively short interval lengths (e.g., 3, 4, 5, 10, or 15 min). Shorter sampling intervals (≤ 2 min) are required to accurately measure aspects of lying behavior such as number of lying bouts per day. The automated monitoring systems are time- and labor-saving tools that can be used by research or on farm to assess cow comfort related to lying behavior.

Sex-Age Related Rumination Behavior of Père David's Deer under Constraints of Feeding Habitat and Rainfall

Extensive studies have been conducted on the rumination behavior of domestic herbivores. However, studies on wild animals are limited, particularly wild animals with specific ruminating parameters. In this study, Père David's deer, a previously extirpated species, was observed to analyze the effects of sex-age, feeding habitat, and rainfall on rumination behavior in the Dafeng Nature Reserve, China. Rumination behavior was investigated based on four parameters: proportion of bedding time spent chewing, bolus processing time (s/bolus), chewing frequency (chews/bolus), and chewing rate (chews/s). Results showed that all three factors affect rumination behavior. The extent of their effects varied based on the four rumination parameters. Chewing rate and frequency decreased based on sex-age levels, i.e., from fawns to juvenile female, juvenile male, adult female, stag, and harem holder. Therefore, body size played a major role in shaping rumination behavior. Deer found in grasslands could chew faster compared with deer found in woodlands. This result might be caused by the effects of dietary composition and sunlight intensity. A deer spends a longer time ruminating while bedding during rainy days compared with rainless days to maximize energy and nutrition intake and compensate for the loss of feeding time during rainy days. Therefore, rumination behavior is plastic and is shaped by intrinsic and extrinsic factors.

Effects of dietary nonstructural carbohydrates and protein sources on feeding behavior of tethered heifers fed high-concentrate diets

To describe the feeding behavior of growing heifers fed high-concentrate diets with different sources of protein and nonstructural carbohydrates, and to explain the ruminal fermentation pattern, 4 ruminally fistulated Holstein heifers (BW = 132.3 +/- 1.61 kg) were assigned to a 4 x 4 Latin square design with a 2 x 2 factorial arrangement of treatments. Two non-structural carbohydrate sources (barley and corn) and 2 protein sources [soybean meal (SBM) and sunflower meal (SFM)] that differ in their rate and extent of ruminal degradation were combined, resulting in a synchronized, rapid fermentation diet (barley-SFM), a synchronized, slow fermentation diet (corn-SBM), and 2 unsynchronized diets consisting of a rapidly and a slowly fermenting component (barley-SBM and corn-SFM). The corn-SFM diet resulted in a lower frequency of feeding (P < or = 0.05), longer meal length (P < or = 0.043), and larger meal size (P < or = 0.037) than the other 3 diets. Dietary treatment had no effect (P > or = 0.09) on the daily percentages of posture and behaviors. In general, heifers spent 9.97 +/- 0.83% of the day eating, 2.11 +/- 0.42% drinking, 25.13 +/- 1.36% ruminating, 16.97 +/- 1.42% in other activities such as social behavior and self-grooming, and the rest of the day (45.82 +/- 2.55%) resting or doing no chewing activities. Eating, drinking, and social behaviors were performed while standing (P < or = 0.01), whereas resting and ruminating occurred mainly while lying (P = 0.001). Eating took place mainly in the first 4 h after feeding (P = 0.001), whereas ruminating occurred mainly at night (P = 0.001). When chewing activities (eating and ruminating) were expressed per kilogram of DM or NDF from roughage intake, more time (P = 0.004) was spent chewing per kilogram of DMI for barley-based diets, and per kilogram of NDF from roughage intake for barley- (P = 0.01) and SFM- (P = 0.002) based diets. Tethered heifers fed the more fermentable and rapidly synchronized diet (barley-SFM) reduced intake and increased chewing time. With these high-concentrate diets, time spent chewing was inversely related to roughage intake.

Chewing activities and oesophageal motility during feed intake, rumination and eructation in camels

It was the aim of this study to characterize rumination behaviour, eructation and oesophageal motility in camels to identify similarities and differences between camels and domestic ruminants. Recordings were carried out in five camels fed on a hay-based diet. On an average, the duration of rumination, feeding and resting was 8.3, 5.6 and 10.1 h per 24 h, respectively. Rumination activity peaked in the morning between 9:00 and 11:00 and in the night between 02:00 and 04:00 a.m. During rumination periods, on an average 67 boluses were regurgitated per hour. Each bolus was chewed for an average of 45 s with 68 chews per min. The pause between two rumination cycles lasted on an average 9 s. Hay intake took 61 min/kg dry matter (DM), rumination lasted 71 min/kg DM of hay consumed. The regurgitation of a bolus started with a contraction of cranial compartment 1 (C 1) during a B-sequence, followed by a deep inspiration with closed glottis. Digesta enters the oesophagus, and an antiperistaltic wave transported the bolus orally. Eructation starts with a contraction of the caudal C1 during a B-sequence when the cranial C1 is relaxed. After entering the oesophagus, a rapid antiperistaltic wave transports the gas orally. Results revealed that the parameter values obtained in the camels were remarkably similar to those in domestic ruminants despite profound morphological differences and different patterns of forestomach motility.

A new method of measuring diet abrasion and its effect on the development of the forestomach

Twelve newborn Holstein bull calves were used to evaluate the effects of dietary abrasiveness, determined by a new method, on ruminal development. Calves were blocked by age and body weight and were assigned to one of three different diets. Each diet had the same ingredients but different particle sizes, which resulted in different abrasive values. No differences were detected in molar percentages of volatile fatty acids in ruminal fluid or in plasma concentrations of urea, glucose, or beta-hydroxybutyrate. The pH of ruminal fluid was lower for calves fed the fine and intermediate diets than for those fed the coarse diet. Digesta-free weights of the stomach and stomach compartments were similar among calves fed the three diets, except that omasum weights were heavier for calves fed the fine diet. Length of the ruminal papillae increased as the abrasive value of the diet decreased. Measurements of ruminal tissue layers from the ventral floor of the cranial sac were not different among diets, but the keratin portion represented more of the epithelial layer for calves fed the diet with the lowest abrasive value, thus decreasing the percentage of metabolically active tissue for those calves.

Interactions among forages and nonforage fiber sources

Source, amount, and physical characteristics of dietary forage can interact with nonforage fiber sources and influence ruminal and total tract fiber digestion, passage, and performance of dairy cows fed diets containing substantial nonforage fiber in place of forage. Dietary NDF from forage can be reduced to < = 60% and still provide sufficient amounts of effective fiber for FCM production that is similar to or superior to that with high forage diets. Because of small particle size and high specific gravity, increased ruminal rate of passage may be responsible for lower ruminal NDF digestibility of nonforage fiber sources fed at high dietary amounts. As the amount of soybean hulls increased from 50 to 95% of a pelleted mix for dairy cows, passage rate increased by 8%. In five studies, the digestion of soybean hull diets was improved by the addition of coarse forage. Fiber digestibility might have improved because coarse hay increased ruminal retention time of nonforage fiber sources and allowed more complete digestion. Addition of coarsely chopped alfalfa hay to diets based on silage containing 25% soybean hulls increased ruminal mat consistency by 49% and tended to slow the ruminal escape rate of soybean hulls by 16%. When high percentage of nonforage fiber are fed, the amount of dietary forage is necessarily low, and forage particle size should be adequate to stimulate rumination and entrap small feed particles. The amount and particle size of forage in the diet interacts with the substituted nonforage fiber source to determine the net impact on the rate of ruminal digestion and passage of nonforage fiber.

Creating a system for meeting the fiber requirements of dairy cows

Current NRC recommendations for dairy cattle provide limited guidance to nutritionists for meeting the fiber and carbohydrate needs of lactating cows. The NRC provide only minimum recommendations for fiber and no accommodation for factors such as physical effectiveness of fiber, interactions with nonfibrous carbohydrates, or animal attributes, which can affect the optimality of dairy rations. To be an improvement, any new system for meeting the fiber requirements of dairy cows must be based on 1) feed characteristics that can be defined and preferably be determined quantitatively using routine laboratory methods and 2) animal requirements that correspond to critical feed characteristics and vary with feeding situation, ration composition, and attributes of the animal. Published data were used to develop coefficients for defining the physical effectiveness or roughage value of feeds and the fiber requirements of dairy cows. Information in this paper is intended to provide practical guidelines for improving current fiber recommendations and to serve as an idealized framework for future research on meeting the fiber requirements of dairy cows. The system is based on NDF as the measure of total chemical fiber in feeds. Adjustments for the effectiveness of NDF in maintaining milk fat production and optimizing ruminal fermentation are based on the particle size and inherent characteristics of NDF that affect chewing activity, ruminal pH, and milk fat production.

Relationship between fermentation acid production in the rumen and the requirement for physically effective fiber

The content of ruminally fermented OM in the diet affects the fiber requirement of dairy cattle. Physically effective fiber is the fraction of feed that stimulates chewing activity. Chewing, in turn, stimulates saliva secretion. Bicarbonate and phosphate buffers in saliva neutralize acids produced by fermentation of OM in the rumen. The balance between the production of fermentation acid and buffer secretion is a major determinant of ruminal pH. Low ruminal pH may decrease DMI, fiber digestibility, and microbial yield and thus decrease milk production and increase feed costs. Diets should be formulated to maintain adequate mean ruminal pH, and variation in ruminal pH should be minimized by feeding management. The fraction of OM that is fermented in the rumen varies greatly among diets. This variation affects the amount of fermentation acids produced and directly affects the amount of physically effective fiber that is required to maintain adequate ruminal pH. Acid production in the rumen is due primarily to fermentation of carbohydrates, which represent over 65% of the DM in diets of dairy cows and have the most variable ruminal degradation across diets. The non-fiber carbohydrate content of the diet is often used as a proxy for ruminal fermentability, but this measure is inadequate. Ruminal fermentation of both nonfiber carbohydrate and fiber is extremely variable, and this variability is not related to the nonfiber carbohydrate content of the diet. The interaction of ruminally fermented carbohydrate and physically effective fiber must be considered when diets for dairy cattle are evaluated and formulated.

Effects of feeding practices on milk fat concentration for dairy cows

Thirty-seven dairy farms, using high producing (7500 kg/yr per cow on average) Montbéliarde cows that were fed hay-based rations, were included in a detailed survey involving the structure of the farm and the herd, the quality of forage, the feeding practices in winter and summer, and genetic characteristics of the cows (breeding values and herd effects). These data were used to analyze variation in milk fat concentration among farms, particularly variation linked to environmental factors, as assessed by the herd effect. When farms were ranked according to herd effect of fat concentration, farms with the highest herd effects fed concentrate to cows in rolled form, distributed forage before or with the concentrate, and provided hay in the trough in summer. The effects of such practices on digestive phenomena in the rumen are discussed. This study supported the use of herd effects to identify factors related to variation in dairy cow performance.