Ground Hay Research Articles

Influence of Ration Physical Form and Nitrogen Availability on Ruminal Morphology of Growing Bull Calves

Male Holstein calves were fed complete diets containing three physical forms (ground and chopped hay and all concentrate) and three rumen degradable protein percents. Calves were slaughtered at 20 wk of age. Weights of reticulorumen with and without contents were recorded. Proportions of mucosa and muscle and gross morphology were determined on excised rumen wall. From nine additional calves rumen epithelial tissue was obtained for light microscopic examination of papillae to determine length, width, surface area, and morphological condition.Weights of reticulorumen with contents were heaviest for calves fed ground hay and tissue weights heaviest for calves fed concentrate. Ruminal content volume was greater for calves fed diets containing hay compared to all concentrate. Hay contents tended to be drier and less dense than concentrate contents.Ruminal epithelial lining was heavier in concentrate-fed and had more mucosa to muscle compared to rumen of calves fed ground or chopped hay. However, papillary length, number of papillae per field, and surface area/field was greater in calves fed hay. Morphological abnormalities of the rumen epithelium occurred more frequently in calves fed concentrate. Reticulorumen measures were unaffected by degradable protein percent. Absorptive capacity of calves fed all concentrate diets decreased compared to calves fed diets with 40% hay.

Short and long term effects of feeding supplements of oats, wheat and lupin grain on the production of ewes lambing in autumn

Four groups, each of about 40 Border Leicester x Merino ewes due to lamb in May, 1978, were held on bare ground and hand-fed poor quality hay, either alone or with oat, wheat or lupin grain at 270 g dry matter/head.d, from two weeks before until six weeks after lambing. A fifth group of ewes grazed separately on green pasture. After hand-feeding ceased in July 1978, ewes from all five groups grazed together and were re-joined with rams in November-December. Increases in wool production (90-230 g greasy fleece), milk production (9-23 ml/h) and growth of lambs (20-4 1 g/d) resulted from feeding supplements to the hay-fed ewes. Ewes fed oats and lupins performed best and, compared with those fed wheat, produced fewer fleeces with major faults (8 and 12% vs 29%, respectively) and less milk (58 and 62 ml/h vs 49 ml/h, respectively). At the end of hand-feeding, the ewes were 18-23 kg lighter than those that had been at pasture, but by the time joining took place in November-December, the difference was only 4-8 kg. Ewes fed hay alone mated 8-12 d later and lambed 5-9 d later (May 1979) than ewes in all other groups. Also, 6% of the ewes fed lupins or allowed to graze pasture during lambing in 1978 were barren in 1979, compared with 25% of barren ewes in all other treatments. It was concluded that wheat, in contrast to lupins and oats, was an inadequate supplement for lambing ewes consuming only low quality roughage.

Associative effects of mixed feeds. II. The effect of dietary addition of bicarbonate salts on the voluntary intake and digestibility of diets containing various proportions of hay and barley

1. (1) In the first of two experiments, fixed amounts of barley were offered, with hay freely available, while in the second, fixed ratios of hay and barley were offered ad libitum. 2. (2) Grinding the hay increased daily dry matter (DM) intake in both experiments, but decreased the digestibility of DM, organic matter (OM) and acid detergent fibre (ADF). The addition of barley depressed the extent of fibre digestion in both ground hay (G) and chopped hay (L) based diets. 3. (3) In the first experiment the inclusion of bicarbonate salts increased the DM and OM digestibility of diets based on ground hay, but not the digestibility of the chopped hay diets. Barley did not depress hay digestibility when it was given with chopped hay or with ground hay diets containing bicarbonate. Both DM and OM digestibility were markedly depressed when barley was added to ground hay diets without bicarbonate. The DM digestibility was reduced by up to 12.2% and that of the hay fraction by 37.2% when ground hay was supplemented with 60 g barley/kg 0.75 per day. 4. (4) The second experiment demonstrated that although DM and OM digestibility increased linearly with the proportion of barley in the diet, the coefficients were significantly less than those calculated as the weighted mean of the separately determined coefficients of the component feeds. The maximum deviation from linearity (i.e. the expected digestibility) occurred when a diet composed of ground hay/pelleted barley (1:2) was offered, the DM digestibility being depressed by over 9%. If the digestibility of barley was not affected, the digestibility of the hay was reduced to 31.2%, compared with 51.1% when it was given alone (i.e. a depression of nearly 40% in the digestibility of the hay). 5. (5) When bicarconate salts were included in the second experiment there was no evidence of such associative effects. 6. (6) It was concluded that negative associative effects could be largely avoided if the rumen pH was maintained above the level inhibitory to cellulolysis. It was suggested that this could be partly achieved by offering roughage in a long form, so stimulating salivation, or by the inclusion of additional buffering material, such as bicarbonate salts, in the diet.

EFFECTS OF POSTWEANING PROTEIN REGIMENS AND UREA ON THE PERFORMANCE OF INTENSIVELY REARED LAMBS

Seven hundred fifty artificially reared lambs that had been weaned from milk replacer at 3 wk of age were randomly assigned, at weaning, to 12 ration sequences: 20% vs 17% dietary crude protein from weaning to 56 days of age, 17% dietary protein from 57 to 98 days of age and 17 vs 14% dietary protein from 99 to 140 days of age and each of the resulting four dietary protein concentration regimens with the protein being provided as natural protein throughout, with 30% of the protein being provided as urea throughout or with 30% of the protein being provided as urea from 57 to 140 days of age. The diets contained 72% corn-soybean meal, or corn-soybean-meal-urea and 20% ground hay, providing about 3 mcal/kg of digestible energy. Maximum growth performance was achieved by the lambs fed diets containing only natural protein in the concentration sequence of 20/17/17. However, the advantage (though statistically significant at a probability of 0.05) was small and slightly lower gains with the protein sequence of 17/17/14 might prove economical because of the savings in expensive protein supplement. There was generally no advantage in growth performance as a result of 17% vs 14% dietary protein after 98 days of age. The results also indicated that such lambs can adapt to, and utilize, urea but that introduction of urea should be delayed for about 2 wk after weaning to allow sufficient time for development of fully functional rumens. Key words: Lambs, protein requirements, urea, artificially reared, early weaned

Replacing Twenty Percent of Concentrate with Ground Hay in an Alfalfa-Based Diet for Cows in Early Lactation

The objective was to observe performance of cows in early lactation when high quality ground alfalfa hay replaced part of dietary concentrate. Multiparous Holsteins were in two groups of 10 based on previous production and lactation number. Rations consisted of alfalfa-grass hay, alfalfa haylage, and concentrate based on corn, oats, and soymeal. Ground alfalfa replaced 20% of ingredients of the concentrate fed the experimental group. Individuals were fed to extent of appetite with restriction that concentrate dry matter did not exceed 65% of intake (52% if ground hay was considered as forage). Cows were on trial for 109 days, beginning 3 days postpartum.Daily intakes of dry matter averaged 26.0 and 25.1kg by the control and experimental groups; that of protein was 4.4 and 4.1kg. Dry matter digestibilities, determined by the acid insoluble ash procedure, were similar. Milk yields were 36.9 and 33.5kg per cow daily by control and experimental animals. Fat percentages averaged 3.2 and 3.7 making yields of fat-corrected milk similar. Both groups averaged 3.2% milk protein. Changes of body weight were similar.

The inclusion of ground hay, straw and paper in the diets fed to growing rabbits

In 3 experiments growing rabbits were divided into 2 groups. In each case half received a basal ration while the other half was given this ration supplemented with a ground fibrous material: 20% hay, 10% straw or 10% paper. All the diets were fed in pelleted form. In all the experiments the rabbits fed on the diets containing the added fibrous materials gained in weight slightly more rapidly and had slightly higher food conversion ratios than did those on the control diet, but the differences in the means were not significant. A study of the small intestine and caecum weights expressed as percentages of body weight and as the weights of 1-cm lengths showed that the added fibrous materials increased these weights except in 1 instance where the results were the same. Significant changes were recorded in the case of hay in both the percentage weight and the weight of 1-cm lengths of caecum and in the straw experiment in the weight of 1-cm lengths of small intestine. There were no significant changes in the results from the paper-fed rabbits.

Zooplankton production and manipulation in striped bass rearing ponds

Zooplankton production and survival of striped bass fry ( Morone saxatilis) were examined in ponds treated either with organic fertilizer (in 1980) or with a combination of organic and liquid inorganic fertilizers and inoculated with Daphnia pulex (in 1981). In 1980, there were significant differences in water quality variables and chlorophyll α levels among treatments in three series of three ponds fertilized only with different amounts of ground hay. Production of crustacean zooplankton was low, and rotifer populations increased as the number of crustaceans was reduced by predation. Electron transport system (ETS) activity was low in all treatments. Survival of striped bass differed greatly within and between treatments, ranging from 1 to 64% and averaging 17%. In 1981, water quality variation was less among treatments in four series of three ponds inoculated with Daphnia and fertilized either with chicken litter-chicken manure in combination with liquid ammonium nitrate and phosphoric acid, or with ground hay. Rotifer species were less abundant and numbers of crustacean zooplankton, total protein, and ETS activity were higher than in 1980. Survival of striped bass in 1981 ranged from 1 to 96% and averaged 45% in the ponds fertilized and inoculated with Daphnia. Numbers of striped bass fingerlings produced per hectare and percent survival were significantly greater in 1981 (manure-fertilized ponds) than in 1980 (hay-fertilized ponds). Combinations of organic and liquid inorganic fertilizers and zooplankton inoculation are suggested to develop and maintain the zooplankton forage base in striped bass rearing ponds. Management effort (including the amounts and timing of organic and liquid inorganic fertilizers) should be shifted to maximize crustacean zooplankton foods during the period 2 weeks before and 2 weeks after the fish are stocked.

Título en español

En dos pruebas realizadas en el Valle de Lajas se evaluó el potencial nutritivo del mosto de melaza deshidratado al incluirse en dietas completas para novillas Charbray en crecimiento con aproximadamente 16% de proteína bruta (CP), que contenían 50% de heno de yerbas tropicales molido, 15% de harina de atún, 10% de melaza y diferentes proporciones de maíz amarillo y mosto. En las dos pruebas, se usó el ritmo de crecimiento, la eficiencia de utilización de alimento y la salud general de los animales como criterios comparativos. En la primera se les suplió cinco niveles de mosto deshidratado (0, 3, 6, 9 y 12%) por 64 días, a cinco grupos diferentes de tres novillas cada uno, cuyo peso inicial aproximado era 190 kg. Los grupos originalmente incluidos que recibían 15, 18 y 21% de mosto deshidratado, fueron eliminados por la falta de crecimiento o crecimiento lento, y porque algunas de las novillas fueron certificadas como preñadas. En el segundo estudio se compararon cuatro niveles de mosto deshidratado (0, 8, 12 y 16%) en dietas idénticas a las usadas en el primer estudio, en novillas de peso inicial aproximado de 280 kg, que se alimentaron por 84 días dentro de las mismas condiciones del primer estudio. En ambas pruebas, niveles de mosto superiores al 6% de la dieta disminuyeron la tasa de crecimiento de los animales, pero más marcadamente a partir del 9%. La utilización del alimento fue menos eficiente cuando se usaron niveles de mosto más altos del 12% de la dieta. Ningún animal, ni aun los que recibieron dietas con 21% de mosto deshidratado, padecieron de diarrea, como ocurrió en estudios anteriores con pollos, gallinas ponedoras, cerdos en crecimiento y guineas, al usarse dietas con niveles de mosto deshidratado entre el 10 y el 15%. La salud de todos los animales que se usaron en ambas evaluaciones fue excelente. El ritmo de crecimiento y la eficiencia de utilización del alimento de los animales disminuyó según estos aumentaron de peso (al comparar datos del estudio 1 contra el 2). No obstante, dietas completas de este tipo que contenían niveles moderados de mosto, promovieron un crecimiento muy bueno para las condiciones semiáridas del valle de Lajas y el sur de Puerto Rico en un sistema de corral de ceba, una tasa de y crecimiento y una eficiencia de conversión que se podría superar aún más en futuros estudios si se aumentase la densidad calórica de la dieta según los animales aumentasen de peso.

Growth and Nitrogen Balance of Calves Fed Rations of Varying Nitrogen Degradability and Physical Form

Effects of degradable nitrogen and ration physical form on dry matter intake, gain, feed efficiency, and digestibility were tested in a 3 x 3 factorial arrangement of treatments in a completely randomized design with 54 male Holstein calves. Nine rations were formulated from data obtained via the bag technique. Calves were fed from 8 to 20 wk of age. Three calves from each treatment were in a nitrogen balance study, and digestibilities of dry matter and nitrogen as well as nitrogen retention were measured. Calves fed all-concentrate rations had greater digestibility and nitrogen retention than calves fed rations containing hay. Calves fed chopped hay consumed less dry matter and gained less than calves fed either ground hay or all-concentrate rations. Feed efficiency was highest for calves fed all-concentrate rations. Nitrogen degradability did not affect dry matter intake, weight gain, or feed efficiency. Calves fed rations with the lowest degradable nitrogen retained more nitrogen per unit of metabolic body size and utilized nitrogen more efficiently than calves fed rations containing higher ruminal degradable nitrogen although not always significantly more. Protein degradation determined by the bag technique may have potential for formulating rations to improve efficiency of nitrogen utilization.

Silage and milk production: a comparison between long, chopped and ground hays as supplements to silage of high digestibility

AbstractGrass silage made in May from S24 perennial ryegrass had a DM concentration of 262 g kg‐1 and an in vitro D‐value of 0·698, and was given ad libitum to twelve Ayrshire cows in a 16‐week feeding experiment. In addition supplements of hay with a mean in vitro D‐value of 0·603 were offered in one of three forms—long, chopped (12·1 mm) or ground (0·80 modulus of fineness) and cubed—and of concentrates given at either 2 or 4 kg per 10 kg milk. Hay averaged 18·2% of total forage DM intake with mean daily intakes of 1·28, 1·22 and 2·26 kg DM per cow in the long, short and ground forms respectively. The highest daily intakes of forage, i.e. silage plus hay, occurred on the ground hay treatments, with values of 10·24 and 9·25 kg DM per cow on the 2 and 4 kg concentrate treatments respectively. The mean daily milk yields were 18·2,18·2 and 19·2 kg per cow on the long, short and ground hay treatments respectively but the increase in yield with the ground hay was only significant at the low level of concentrate intake. The hay treatments had small and non‐significant effects on milk composition. It is concluded that ground hay was superior to either long or chopped hay as a supplement for silage, but the small advantages depended on the level of concentrate intake.

Influence of Ration Physical Form, Ruminal Degradable Nitrogen and Age on Rumen Epithelial Propionate and Acetate Transport and Some Enzymatic Activities

Holstein bull calves were used to determine the influence of degradable nitrogen and ration physical form on rumen epithelial transport and enzymic activity. Rations contained 30, 45 and 60% ruminal degradable nitrogen (RDN), each with three forms (ground hay, GR; chopped hay, CH; and all concentrate, CONC). Rumen tissue samples were obtained by biopsy (8 weeks) and at slaughter (20 weeks). Acetate transport across rumen epithelium increased between 8 and 20 weeks in calves fed GR and CH, but not in calves fed CONC. Propionate transport was highest in calves fed GR and lowest in calves fed CONC at both 8 and 20 weeks. Transport of acetate and propionate was incresed with increasing RDN at 20 weeks. There were no differences in ruminal tissue lactate production. Rumen papillae of calves fed CONC were abnormal in morphology and at 20 weeks dry mucosal weights (mg/cm2) were highest. Lactate dehydrogenase and NADP-malic dehydrogenase activities were not different. Propionyl CoA synthetase activity was higher in 20-week calves fed CONC, compared to GR to CH. Glutamate dehydrogenase and aspartate aminotransferase activities were highest in 20-week calves fed 60% RDN rations, regardless of physical form.

Effect of Feeding Isoacids with Urea on Growth and Nutrient Utilization by Lactating Cows

In the growth study 10g each of isobutyrate, isovalerate, 2-methylbutyrate, n-valerate, and phenylacetate were mixed with 80g of urea, 50g of molasses, and 270g of ground hay and fed to nine dairy heifers for 90 days. The control group was fed the same diet minus isoacids and phenylacetate. All animals were fed ad libitum timothy hay as the sole roughage.In the digestion trial, two mixtures of isoacids and a control ration were fed to nine lactating cows in a 3×3 Latin square design with 28-day feeding periods. Corn silage was the sole roughage, and concentrate was fed in proportion to milk production. Collection of feces and urine was for the last 5 days of each period.Mixture 1 of isoacids contained on a molar basis 28, 24, 24, and 24% of isobutyrate, isovalerate, 2-methylbutyrate, and n-valerate, respectively. Corresponding for mixture 2 were 36, 17, 17, and 30%.Addition of isoacids increased growth rate of younger animals but not older ones. The isoacid mixtures improved utilization of nitrogen by lactating cows. Urinary nitrogen decreased, and retention of absorbed nitrogen increased. Digestibility of dry matter and nitrogen were not affected by isoacid additions.

Ensiling Characteristics, Digestibility and Feeding Value of Ensiled Cattle Waste and Ground Hay with and without Sodium Hydroxide

Ensiling Characteristics, Digestibility and Feeding Value of Ensiled Cattle Waste and Ground Hay with and without Sodium Hydroxide

Starting Rations and Procedures for Stressed Calves

Many interstate and intrastate shipments of yearlings and calves occur each year throughout the United States. Because they have been exposed to a wide range of conditions, it is difficult to decide on which rations and management techniques should be used to obtain efficient, economical gains. These studies were designed to help develop procedures and starting rations for stressed calves so that some of the above management decisions could be made with a higher degree of confidence. In summary, calves performed better when fed a ground alfalfa hay ration. Yearlings performed best on the corn silage ration. Therefore, results from these trials substantiate results from other studies that suggest that prior nutrition (feeding regime) of cattle greatly influence their adaptability to various rations. These results indicate that stressed calves undergoing weaning stress seem to adapt and perform better on ground hay rations while cattle past the stresses of weaning appear to perform well on either corn silage or ground hay rations.

The effects of shearing on the heat production and activity of sheep receiving dried grass or ground hay

SUMMARY1. Oxygen consumption was measured in two experiments using castrated Romney male sheep both shorn and unshorn. The sheep were fed either ground hay or dried grass. An ambient temperature of 13°C ± 1°C was maintained at all times. In Experiment 1, oxygen consumption was measured with eight sheep using a respiration chamber and in Experiment 2, oxygen consumption was measured with four sheep using a ventilated hood. The times spent standing, lying, eating and ruminating were measured in Experiment 2. Heat production was calculated from the measured values for oxygen consumption.2. Heat production increased following shearing in both experiments. In Experiment 1, heat production of the sheep receiving dried grass was significantly greater (P<0·05) on days 1, 8 and 16 following shearing, compared with pre-shearing values. For sheep receiving ground hay, heat production was greater on day 1 (P<0·05) and day 8 (P<0·01) following shearing, compared with pre-shearing values. The mean maximum increase in heat production following shearing was 2·3 MJ/24 hr (25% increase) for sheep receiving dried grass and 1·2 MJ (17%) for those receiving ground hay.3. The patterns of change in heat production following shearing in Experiment 2 were similar to those observed in Experiment 1 although the maximum increases were smaller: 21% for the sheep receiving dried grass and 13% for those receiving ground hay.4. The time spent standing increased considerably after shearing and this change in behaviour made a large contribution to the increase in energy expenditure after the sheep were shorn.

The influence of the level of feeding on fermentation in the rumen of sheep receiving a diet of ground barley, ground hay and flaked maize

SummaryFive rumen-cannulated sheep were given a diet of ground barley, ground hay and flaked maize in quantities which were increased progressively throughout the period of study. The rumen concentration of total short-chain fatty acids increased (P < 0·05) and the pH decreased (P< 0·05) as the level of feeding was raised and pH was correlated with the fatty acid concentration. There were no systematic effects of the level of feeding on the volume, outflow rate or clearance rate of the rumen liquid phase or on the ruminal concentration of ammonia. The molar percentage of acetic acid in the rumen fluid tended to decrease as the level of feeding was raised and there were compensatory increases in the percentage of propionic acid. However, there were wide variations in the composition of the mixture of rumen acids between sheep at each level of feeding and changes in fermentation pattern with level of feeding were not consistent between animals.A broad inverse relationship was observed between the molar percentage of propionic acid and the clearance rate of the rumen liquid phase which supports the suggestion that there is an important association between the pattern of fermentation in the rumen and the liquid clearance rate.

FEED INTAKE AND NUTRIENT DIGESTIBILITY OF GROWING LAMBS SUPPLEMENTED INTRAGASTRICALLY WITH FULL-FAT RAPESEED (CV. TOWER)

Seventeen lambs were used to study the effects of ruminal and/or abomasal infusions of rapeseed on voluntary feed intake, nutrient digestibility and nitrogen retention. The basal diet (65% barley, 30% ground hay) contained 92% dry matter, 12% protein and 3.9 kcal/g of gross energy as fed. In experiment 1, full-fat rapeseed (FFRS, 25% protein, 50% fat) was either heated in boiling water or non-heated and infused into the abomasum of lambs as a 20% solids suspension to provide 25% of the daily energy requirement for maintenance. The intake, nutrient digestion and nitrogen retention of lambs were not affected by the heat treatment. In experiment 2, abomasal infusions of 0, 100, 200 and 400 ml of saline did not affect the "hunger drive" or daily feed intake of lambs. In experiment 3, FFRS (20% solids) was infused into the abomasum at levels of 12.5 and 25% of the energy requirements for maintenance with no infusion as control. Within 30 min post-infusion, voluntary energy intake decreased with increasing levels of FFRS infused (r = − 0.68, P < 0.01), but the total of the energy consumed during this time period plus that infused was not different. Nutrient digestibility, nitrogen retention and average daily gains were not affected by the infusion level. In experiment 4, 15% of maintenance energy requirements were infused as FFRS into the rumen or abomasum. Voluntary energy intake at 30 min post-infusion was lower following infusions into the rumen or abomasum as compared to no infusion (P < 0.01). Daily energy intake, weight gain and nutrient digestibility were not affected by the site of infusion. Nitrogen retention was lower when FFRS was infused into the rumen. In experiment 5, partially extracted rapeseed (31% protein, 15% fat) was infused into the abomasum to supply either 0.1 or 0.2 g of nitrogen per kg0.75 body weight and compared to non-infused controls. Voluntary intake at 30 min post-infusion was lower for lambs that received the infusions (P < 0.02). Daily energy intake and nitrogen retention were not affected by the level of infusion. Nutrient digestibility increased gradually with each level of infusion (P < 0.01). These experiments indicate that intra-abomasal supplementation with Tower FFRS does not improve the performance of growing lambs fed a pelleted diet containing about 12% crude protein. The FFRS protein had low solubility in rumen fluid, in vitro, and therefore may be only partially degraded in the rumen in vivo.

Milk Fat Depression and Rumination Stimulation ,

Stimulating rumination by feeding polypropylene ribbon had no effect in alleviating milk fat depression. In two experiments with six cows in each, milk fat depression was produced by feeding a ground pelleted hay with concentrates and limited long hay. Feeding this ration resulted in a large reduction in time spent ruminating. Adding polypropylene ribbon, 5cm long, returned rumination times to normal but had no effect on milk fat depression. Replacing ground hay with long hay returned both rumination times and milk fat to normal. The effect of long hay in preventing or reversing milk fat depression is due to factors other than its potential for stimulation of rumination.

A relationship between the molar proportion of propionic acid and the clearance rate of the liquid phase in the rumen of the sheep

1. Four rumen-cannulated sheep were given a forage mixture (F) of chopped hay-ground, pelleted, dried grass (92:8, w/w) and two concentrate mixtures (C and S) of ground barley-ground hay-flaked maize (46:24:30 and 56:24:20, by wt respectively) in twenty-four hourly meals each day. Each of the diets was offered in successive periods of 16 d to give a feeding sequence F-S-C-S for one pair of sheep and C-S-F-S for the other pair. 2. The average composition (mol/100 mol) of the mixture of short-chain fatty acids, acetic, propionic and butyric, in the rumen was respectively 70-1, 18-5 and 7-5 with diet F, and 55-8, 24-8 and 13-6 with diet C. With diet S, the pattern of fermentation varied both between animals and in the same animal for different periods having either 'high' (28-39 mol/100 mol) or 'low' (16-21 mol/100 mol) proportions of propionic acid. On average when diet S followed diet F there was less propionic acid in the fermentation mixture than when diet S followed diet C (59-3 acetic, 22-2 propionic and 14-1 butyric as compared with 52-7, 29-4 and 13-1 respectively) but this trend was not significant and there was evidence of interactions between the feeding sequences and the individual sheep. 3. The mean concentrations of ammonia, sodium, potassium and chloride were similar for all diets but the pH and concentrations of calcium, magnesium and phosphorus tended to be higher and the buffering capacity lower for diet F than for diets C or S. In animals receiving diet S there was no relationship between the concentrations of minerals, the pH or buffering capacity and the pattern of fermentation except for ammonia, the concentration of which was high when the molar proportion of propionic acid was low. 4. Rumen volume, outflow rate and clearance rate, determined using polyethylene glycol, were higher for diet F than for diets C and S but within each diet, particularly for diet S, values varied considerably between sheep and between periods. 5. There was evidence of an interrelationship between the molar proportion of propionic acid in the fermentation products and the clearance rate, which indicated that the clearance rate may be an important factor influencing the pattern of fermentation in the rumen.

Pecan Shells as a Roughage in Steer Rations and Use of Rib Cut Density in Estimating Energy Gain

One-Hundred-Ten Angus and Hereford steer calves were assigned by stratified randomization to 11 outcome groups of 10 steers each. One of the 11 groups was slaughtered at the outset to facilitate the use of Lofgreen's comparative slaughter technique, with certain modifications, for estimating energy gains during a feeding trial with the other groups. The remaining groups were randomly assigned to five ration treatments designed to compare ground pecan (Carya illinoensis) shells (GPS) with ground hay (GH) as a roughage in a steer ration. The GH and/or GPS were included along with ground shelled corn, soybean oil meal and minerals in the various ration treatments as follows: (1) 20% GH; (2) 20% GPS; (3) 10% GH; (4) 10% GPS; (5) 10% GH+10% GPS. The steers were self fed on their respective rations for either 140 or 161 days. The GPS caused no reduction in feed intake nor the development of any apparent health problems. However, on the basis of rate of live weight gain, rate of energy gain, feed efficiency and various measures of carcass quality, GPS were inferior to GH as a roughage material. The GPS lowered rumen pH. Also, they had a significant influence on certain other measures of rumen fermentation. In this test GPS contributed very little, if any, nutritive value to the ration. GPS were more effective than GH in reducing the incidence of livers condemned due to abscesses, especially at the 10% level of roughage. A rib cut was used effectively as an indicator of carcass density in estimating energy gains of test animals.