Kilogram Of Dry Matter Research Articles

Optimizing the Level of Wet Corn Gluten Feed in the Diet of Lactating Dairy Cows

Twenty-four multiparous Holstein cows averaging 566±43kg of body weight and 83±49 d in lactation were assigned to treatments stratified by age, days in milk, and milk yield to evaluate the effects of feeding increasing levels of wet corn gluten feed (WCGF) on lactational performance and milk composition. Complete diets containing 0, 15, 30, or 45% of the total ration dry matter (DM) as WCGF were formulated to be 17.2% crude protein and 1.72 Mcal of NEL per kilogram of DM, and fed twice daily to individual cows in Calan gates for 15 wk. All diets had a positive metabolizable protein balance. WCGF did not alter DM intake, but feed intake variance tended to be more consistent among cows fed 15 and 30% WCGF (DM basis). Weight gain was numerically greatest for those cows receiving 45% WCGF. Efficiency of energy and protein utilization was not different among treatments. Milk components of fat, protein, and casein were not different among treatments. Milk urea nitrogen was greater for cows on WCGF. Serum urea nitrogen was greatest in cows fed diets containing 15 and 45% WCGF. Serum insulin was lowest in the groups receiving 30 and 45% WCGF, but serum glucose and total protein were unaffected. The concentration of the ruminal volatile fatty acid, valerate, was greater in cows on the WCGF diet and highest in cows fed 30% WCGF. Ruminal ammonia was greatest in cows receiving 30% WCGF. It was estimated that 18.6% of the dietary DM fed as WCGF as a replacement for both portions of the concentrate and the forage in similar diets would have maximized milk yield without negatively affecting milk composition or feed efficiency.

Optimizing municipal solid waste combustion through organic and elemental carbon as indicators.

The temperature, redox conditions, and residence times of the solid waste on the grate and of the raw gas in the secondary combustion zone determine the mineralization processes of organics in municipal solid waste incinerators. An improved knowledge of the influence of these factors on the incineration process might help to optimize incinerators with regard to mineralization efficiency of organics. This paper presents a method for investigating the influence of process parameters on mineralization of organics to CO2 by using the elemental carbon (EC) and organic carbon (OC) concentrations in the solid residues as indicators. The results obtained by experiments in full-scale incinerators show that the EC concentration in these residues is a good indicator of oxygen supply, whereas the OC/EC ratio is a good indicator of temperature in and above the furnace bed. Very effective burnout of the bottom ash up to 0.95 g of TOC (EC + OC) per kilogram of dry matter (DM) and of the electrostatic precipitator (ESP) ash up to 0.24 g of TOC per kilogram of DM was achieved in a full-scale incinerator.

Barley Processing, Forage:Concentrate, and Forage Length Effects on Chewing and Digesta Passage in Lactating Cows

Dietary factors that alter fermentability, NDF content, or particle size of the diet were evaluated for their effects on chewing behavior and distribution and passage of feed particles in the digestive tract of dairy cows. A double 4 × 4 quasi-Latin square design with a 23 factorial arrangement of treatments was used. The dietary factors were: extent of barley grain processing, coarse (1.60mm) or flat (1.36mm); forage-to-concentrate ratio (F:C), low (35:65) or high (55:45) (dry matter basis); and forage particle length, long (7.59mm) or short (6.08mm). Eight lactating cows with ruminal and duodenal cannulas were offered ad libitum access to total mixed diets. Chewing time, expressed as minutes per day or per kilogram of dry matter or neutral detergent fiber (NDF), was increased with high F:C diets due to increased eating and ruminating times but was decreased when expressed per kilogram of NDF intake from forage. The influence of forage particle length or grain processing on chewing activity was less pronounced than F:C ratio. Chewing activity was positively correlated to proportion of long forage particles in the diet but not to particle length of the diets. Influence of feed particle size on particle size distribution in different sites of the digestive tract was minimal. Particle size distributions of duodenal digesta and feces differed; the proportion of particles retained on the 3.35- or 1.18-mm screens was higher, but proportion of particles that passed through the 1.18-mm screen was lower in duodenal digesta than in feces. Relationships between chewing activities and ruminal pH or fractional passage rate of rumen contents were not significant. These results indicate that particle size of barley-based diets was not a reliable indicator of chewing activity. Forage particle size and NDF content of the diets were more reliable indicators of chewing activity than was the NDF content of forage. Fecal particle size was not an appropriate means of estimating the size of particles exiting the reticulorumen, at least for barley-based diets. Breakdown of coarse particles was necessary, but not a rate-limiting step for particles exiting the rumen. Passage rate of the rumen contents was affected by numerous factors including chewing activity.

Nutritionally Directed Compensatory Growth Enhances Heifer Development and Lactation Potential

The objectives of this study were 1) to examine the interactive influence of a compensatory nutrition regimen and lasalocid supplementation on dairy heifer growth performance and 2) to document the extent to which compensatory growth sustains lactation potential over the first two lactation cycles. Twelve Holstein heifers, weighing an average of 160kg (about 6 mo of age) were randomly assigned to treatments arranged in a 2 x 2 factorial design. Treatment variables were two dietary regimens (control and stair-step compensatory nutrition) and two levels of lasalocid (0 and 200 mg/d). The control heifers were fed a diet containing 12% crude protein (CP) and 2.35 Mcal of metabolizable energy (ME) per kilogram of dry matter. The stair-step compensatory nutrition heifers were subjected to a phased nutrition regimen and reared according to an alternating 3-2-4-3-4-2-mo schedule. The first stair-step (prepubertal phase) consisted of energy restriction [17% CP and 2.35 Mcal/kg of ME] for 3 mo followed by realimentation (12% CP and 3.05 Mcal/kg of ME) for 2 mo. The second step (puberty and breeding) consisted of energy restriction for 4 mo followed by realimentation for 3 mo. The third step (gestation period) was energy restriction for 4 mo concluding with realimentation for 2 mo. Dry matter intake of heifers during the restriction phase was limited to 70% of the control intake. Heifers were given ad libitum access to a high energy density diet during realimentation to allow compensatory development. Stair-step heifers supplemented with lasalocid had the highest efficiency of growth (body weight gain/dry matter intake), suggesting synergistic metabolism of lasalocid with compensatory growth action. Compensatory growth induced during the last trimester enhanced metabolic status by increasing circulating insulin and decreasing triglyceride levels. Heifers on the stair-step regimen had a significant increase in milk yield during the first (21%) and second (15%) lactation cycles. These results support our thesis that compensatory growth induced during an allometric growth phase improves mammary development and energy and protein metabolic status of dairy heifers.

DESEMPENHO DE GENÓTIPOS DE NOVILHOS PARA ABATE AOS CATORZE MESES, GERADOS POR FÊMEAS DE DOIS ANOS

O objetivo deste trabalho foi avaliar o desempenho de machos Hereford (H), ½ Jersey (J) ½ H e 5/8 H 3/8 Nelore (N), gerados por fêmeas acasaladas aos 14 meses de idade, confinados do desmame, aos sete meses, até o abate aos 14 meses, quando atingiram em média 195 kg de carcaça. A relação volumoso:concentrado foi decrescente, iniciando em 70:30 e finalizando em 40:60. O volumoso utilizado incluiu silagem de sorgo forrageiro, cana-de-açúcar e feno de aveia. Os consumos diários de matéria seca e de energia digestível dos três grupos de novilhos não diferiram significativamente, mas os novilhos ½ J ½ H apresentaram maior consumo de matéria seca por 100 kg de peso vivo em relação aos outros dois grupos. Não houve diferença no ganho de peso médio diário durante os 193 dias de confinamento. A eficiência de conversão, expressa em Mcal de energia digestível e em quilogramas de matéria seca, para cada quilograma de ganho de peso, também não diferiu significativamente entre os três grupos testados.

Evaluation of the physical structure of fodder beets, potatoes, pressed beet pulp, brewers grains, and corn cob silage.

The physical structure of fodder beets, raw potatoes, ensiled pressed sugar beet pulp, ensiled brewers grains, and corn cob silage was evaluated in diets containing concentrates and either corn silage or grass silage as the roughage source. In one series of experiments, the chewing activity of eight cows was measured over 4 d. The beet pulp and fodder beets were added to the two roughage sources at two ratios [20:80 and 35:65, dry matter (DM) basis]. Potatoes, brewers grains, and corn cob silage were fed in a fixed amount (5 to 6 kg of DM) with corn silage. The chewing indexes (eating and ruminating time per kilogram of DM ingested) for fodder beets and beet pulp averaged 34.3 and 32.3 min/kg of DM, respectively, and were hardly affected by the nature of the roughage or by the inclusion ratio. The chewing indexes for potatoes, brewers grains, and corn cob silage were 23.7, 56.6, and 41.6 min/kg of DM, respectively. In another series of experiments using 8 to 11 cows, the ratio of roughage to concentrates was lowered weekly by 5 percentage units, and the critical rough-age portion of the diet was determined (i.e., the amount just before a lack of physical structure was observed). The roughage source was either fed alone or supplemented with about 4 kg of DM of the experimental feed. The critical roughage portion of the diet decreased when the experimental feeds were added; the decrease was greatest with ensiled pressed beet pulp and was lowest with corn cob silage.

Effect of Dietary Energy and Protein Concentration on the Concentration of Milk Urea Nitrogen in Dairy Ewes

To study the effects of dietary crude protein (CP) and energy on milk urea N concentrations in dairy sheep, eight pelleted total mixed rations were prepared to obtain two levels of energy density (1.65 and 1.55 Mcal of net energy for lactation per kilogram of dry matter for high energy and low energy rations, respectively) and four concentrations of CP within each energy level (mean CP concentrations, 14.0, 16.4, 18.7, and 21.2% of dry matter). The experimental design consisted of two 4 × 4 Latin squares (one per energy level) with two replications per treatment within each 3-wk period. Milk urea N concentrations were similar between dietary energy levels. Within each energy level, milk urea N was linearly and positively associated with dietary CP content and intake (range of milk urea N concentrations, 12.2 to 25.8 mg/dl for ewes fed high energy rations and 12.9 to 26.7 mg/dl for ewes fed low energy rations). The comparison of these results with those from other trials suggested that milk and blood urea N concentrations are closely correlated with dietary CP concentrations and less closely correlated with dietary CP intake. Our results suggest that milk or blood urea N concentrations can be used as indicators of protein metabolism and intake of lactating ewes.

Ungulate Grazing in Sagebrush Grassland: Mechanisms of Resource Competition

In many areas of western North America, populations of Rocky Mountain elk (Cervus elaphus canadensis) avoid snow at high elevations during winter by migrating to sagebrush grassland communities in mountain valleys, communities that are used by cattle in the spring and early summer. As a result of these patterns of habitat use, the impact of elk on forage supplies for cattle has emerged as an important issue in range and wildlife management throughout the West. We examined effects of variation in population density of elk on the availability and use of forage resources by cattle in a randomized complete block experiment conducted in sagebrush grassland during four years. We manipulated elk numbers to achieve four levels of population density (0, 9, 15, and 31 elk/km2), replicated each level three times, and observed responses of vegetation and cattle to these manipulations. At high densities (31 animals/km2), elk annually removed 57% of the standing crop of dead perennial grass and 12% of the total annual production of live perennial grass. Standing crops of dead perennial grass in early spring declined in direct proportion to increasing elk density (linear effect F1,6 = 10.0, P = 0.02) from a mean of 8.7 g/m2 in the controls (0 elk/km2) to 3.3 g/m2 in the high density (31 elk/km2) treatment. Early spring standing crops of live perennial grass also declined as elk population density increased, but these trends only approached significance (linear effect F1.6 = 3.4, P = 0.12). Effects of elk grazing on herbaceous aboveground net primary production were not significant (minimum P > 0.38), but the total supply of herbaceous dry matter available to cattle (standing dead + primary production) declined in linear relation to elk density (linear effect F1.6 = 7.7, P = 0.03). Canopy cover of shrubs was least and canopy cover of grass was greatest at intermediate levels of elk density (quadratic effect F1.6 = 9.4, P = 0.03). We found weak enhancing effects of elk populations on nutritional quality of spring forage. Elk grazing caused linear increases in the digestibility (F1.6 = 5.0, P. = 0.07) and nitrogen content (F1.6 = 15.1, P = 0.008) of perennial grass available to cattle. Nitrogen content of cattle diets increased in the moderately grazed treatments (control vs. 15 elk/km2, F1.6 = 4.3, P = 0.06), but dietary digestibility and fiber content did not change significantly with treatment. Daily forage intake by cattle (kilograms of dry matter per cow per day) declined in direct relation to elk density (F1.6 = 5.2, P = 0.06), primarily as a result of reductions in intake of standing dead grass. Consequently, cattle daily intake of digestible energy (linear effect F1.6 = 5.1, P = 0.06) and nitrogen (control vs. others F1.6 = 5.4, P = 0.06) declined as elk population density increased. The mechanism responsible for this decline was a Type II functional response of cattle to forage biomass. We conclude that effects of elk on cattle represent a composite of facilitative and competitive effects. When forage production is low and cattle density is high, competition is a much stronger force than facilitation.

Response of rainbow trout (Oncorhynchus mykiss) growing from 50 to 200 g to supplements of dibasic sodium phosphate in a semipurified diet.

Effects of increasing dietary concentrations of phosphorus on growth, feed intake, feed conversion, composition of gain and concentration of inorganic phosphate in plasma were studied in rainbow trout. Twelve groups of 20 trout initially weighing 53 +/- 0.6 g/fish were fed semipurified diets containing 19.6 MJ digestible energy per kilogram of dry matter. Twelve levels of phosphorus ranging from 1.03 to 10.96 g/kg dry matter were achieved by replacing inorganic binder with dibasic sodium phosphate in 11 graded levels. Nonlinear responses of trout to increasing dietary phosphorus concentration determined over 53 d were described using exponential functions. Feed intake, growth rate and feed conversion ratio as well as plasma inorganic phosphate concentration increased with increasing dietary phosphorus concentration. The concentrations of phosphorus, calcium, magnesium and potassium in weight gain increased, whereas concentrations of lipids and energy in weight gain decreased with increasing dietary phosphorus concentration. Concentrations of protein and sodium in weight gain were unaffected. Different concentrations of dietary phosphorus were required for achieving 95% of the plateau value determined for desired traits. In growth rate and phosphorus deposition, the required phosphorus concentrations were 3.7 and 5.6 g/kg dry matter, respectively. However, dietary phosphorus was utilized most efficiently (88%) at a dietary concentration of 2.5 g/kg dry matter. At the dietary phosphorus concentration that resulted in maximum phosphorus deposition (5.6 g/kg dry matter), phosphorus utilization was about 60%. Supplemental phosphorus from dibasic sodium phosphate was completely available to trout which must be considered in formulating recommendations. Based on this work, 0.25 g available phosphorus/MJ digestible energy is recommended for trout diets.

Effects of Varying Sulfate Concentrations on Growth and Mineral Nutrition of the Greenhouse Tomato

In hydroponic recirculating systems, sulfate ions can accumulate to excessive levels and interfere with other nutrient ions. The objective of this research was to determine the effects of four sulfate concentrations on growth and mineral nutrition of greenhouse tomato plants (Lycopersicon esculentum Mill. cv. Trust). Tomato seeds were sown in flats and subsequently transplanted into rockwool slabs. Ten days after transplanting, plants were given four sulfate concentrations in nutrient solutions (S0 = 0.1, S1 = 5.2, S2 = 10.4, and S4 = 20.8 mM). The plots were arranged in a randomized complete-block design with four replications. Treatment S0 reduced dry weight of the top portion of the plant. A sulfate shortage in the nutrient solution decreased S concentrations in the leaf and decreased fruit number. Activities and concentrations of major ions in solutions expressed in mM or as row-centered logratios were correlated with corresponding foliar concentrations expressed in grams of nutrient per kilogram of dry matter or as row-centered logratios. Data were presented in this manner in order to explore interactive models describing relationships between mineral composition of both nutrient solutions and plant tissues. High concentrations of sulfate ions in the nutrient solution up to 20.8 mM did not affect tomato growth or yield. Tomato plants appeared prone to sulfate deficiency, but tolerant to sulfate concentrations up to 20.8 mM in the nutrient solution.

Tailor-made co-generation important to save energy

A daily time step model simulating growth and quality of cool season grasses was developed and validated for smooth brome (Bromus inermis Leyss.) under varying environmental and management conditions. Growth predictions are based upon genetic potential, environmental temperature, leaf area, soil moisture and nitrogen fertilization rate. Daily potential growth rate is a composite of two functions; one relating grass species maximum growth rate to minimum, optimum and maximum temperatures for plant growth, and another relating daily minimum and maximum air temperatures to time. Multipliers are developed for available leaf area, moisture and nitrogen, and the minimum of these values modifies the daily potential growth rate to determine daily plant production. Change in sward dry matter digestibility (DMD) is a function of forage material present, daily forage growth and environmental temperature. For dry matter (DM) production, the relationship between model (Y) and observed (X) estimates (kilograms of dry matter per hectare) yielded the regression equation: Y = 218 + 0·94X; SE = 431; R2 = 0·98. The relationship between model (Y) and observed (X) estimates of DMD (%) gave the regression equation: Y = 2·24 + 0·97X; SE = 1·78; R2 = 0·90. The above validation shows that the mathematical logic contained within the plant model accurately predicted smooth brome production and changes in forage quality. Intercept and slope values were similar to 0·0 and 1·0, respectively, and standard error values were similar to observed experiments.

Epidemiology of trichostrongylidosis in cattle: development of infective larvae in the second part of the grazing period and their contribution to infections in the same year

A grazing experiment was performed in the Swiss midland region with 22 first-season calves which were grazed together from May to mid July when they were allocated to two equal groups, one receiving a morantel sustained-release trilaminate bolus (Paratect Flex®) bolus, Pfizer, Zurich, Switzerland) and the other one remaining as an untreated control. Each group was moved to a clean pasture on 21 July. The larval contamination on the pasture with the control animals reached 4652 third stage larvae (L 3) per kilogram of dry matter (L 3 kg −1 DM) after 10 weeks. Parasitic gastroenteritis was observed in two calves of the control group in August, and mean serum pepsinogen levels exceeded 4000 mU tyrosine in this group in September. Eggs from Ostertagia sp. and Cooperia sp. that were excreted by the animals at the beginning of July and the end of August showed similar hatching rates of 94% and 99%, respectively. In the calves of the bolus group the egg output was reduced by 95% within 14 days of administration of the bolus. Larval contamination on the pasture of the bolus group was zero until the beginning of September when a slight increase occurred, reaching 793 L 3 kg −1 DM in October. At the end of the trial the bolus-treated calves had a mean weight gain advantage of 18 kg ( P<0.05) compared with the controls. The results confirm that a second generation of larvae developed on pasture in August and September and caused parasitic gastroenteritis in first-year grazing calves in late summer. The relevance of the results for the prophylaxis of parasitic gastroenteritis in calves in mixed grazing systems with calves and older cattle is discussed.

EFFICACY OF ANHYDROUS AMMONIA AND SULFUR DIOXIDE AS PRESERVATIVES FOR HIGH-MOISTURE GRAIN AND THEIR EFFECT ON THE NUTRITIVE VALUE OF BARLEY FOR GROWING-FINISHING CATTLE

The effectiveness of ammonia and sulfur dioxide as preservatives for high-moisture barley grain and their influence on digestibility, rate and efficiency of gain, and the selenium and thiamin status of feedlot steers were examined. Duplicate 18-t plastic-bag bins were prepared with the following type and amount (wt/wt, dry matter (DM) basis) of preservative applied to low (23%) or high (32%) moisture barley: (1) high-moisture barley, no preservative (control); (2) high-moisture barley, 1.1% ammonia (1.1%-NH3); (3) high-moisture barley, 2.3% ammonia (2.3%-NH3); (4) low-moisture barley, 1.3% sulfur dioxide (1.3%-LMSO2); and (5) high-moisture barley, 1.7% sulfur dioxide (1.7%-SO2). Heating occurred in the control barley. Mold and yeast populations were substantially reduced in barley treated with ammonia which appeared well preserved. Considerable deterioration occurred in the core of one 1.3%-LMSO2 bin. Crude protein digestibility was lower (P &lt; 0.001) for an all-concentrate diet containing 1.1%-NH3 barley fed whole (66.8%) than for three other diets containing rolled barley (mean 81.1%), although apparent digestibilities of other feed components were similar (P &gt; 0.05). When the preserved grains were each fed to a group of 12 steers (363 kg initial weight) along with 1.0 kg hay daily, gains were 1.46, 1.72, 1.67, 1.33 and 1.31 kg d−1 (P &lt; 0.05) for steers fed control, 1.1%-NH3, 2.3%-NH3, 1.3%-LMSO2, or 1.7%-SO2-treated barley, respectively. Corresponding kilograms of DM required per kilogram of grain were 6.11, 5.41, 5.53, 6.76, and 6.72 (P &lt; 0.05). Serum selenium concentrations and thiamin status were similar (P &gt; 0.05) for steers in all treatments at the end of the test. Key words: High-moisture barley, steers, preservatives, ammonia, sulfur dioxide

Development and validation of a dynamic model of growth and quality for cool season grasses

A daily time step model simulating growth and quality of cool season grasses was developed and validated for smooth brome ( Bromus inermis Leyss.) under varying environmental and management conditions. Growth predictions are based upon genetic potential, environmental temperature, leaf area, soil moisture and nitrogen fertilization rate. Daily potential growth rate is a composite of two functions; one relating grass species maximum growth rate to minimum, optimum and maximum temperatures for plant growth, and another relating daily minimum and maximum air temperatures to time. Multipliers are developed for available leaf area, moisture and nitrogen, and the minimum of these values modifies the daily potential growth rate to determine daily plant production. Change in sward dry matter digestibility (DMD) is a function of forage material present, daily forage growth and environmental temperature. For dry matter (DM) production, the relationship between model (Y) and observed (X) estimates (kilograms of dry matter per hectare) yielded the regression equation: Y = 218 + 0·94 X; SE = 431; R 2 = 0·98. The relationship between model (Y) and observed (X) estimates of DMD (%) gave the regression equation: Y = 2·24 + 0·97 X; SE = 1·78; R 2 = 0·90. The above validation shows that the mathematical logic contained within the plant model accurately predicted smooth brome production and changes in forage quality. Intercept and slope values were similar to 0·0 and 1·0, respectively, and standard error values were similar to observed experiments.

Effects of pasture type and grazing management in autumn on the performance of dairy cows in late lactation and on subsequent pasture productivity

An experiment at Kyabram, Victoria, studied the effects of pasture allowance on the production of grazing dairy cows in late lactation (autumn). Cows strip-grazed paspalum dominant or ryegrass-white clover perennial pastures for 60 d from March to May. Mean pasture allowances were 23.2, 13.3 or 6.9 kg digestible dry matter/cow.d. Reduced pasture allowance during late lactation reduced milk yield and body condition. This occurred because pasture intake was positively related to pasture allowance. Each additional kilogram of dry matter (DM) eaten produced 0.93 kg milk and 0.045 kg milk fat. Cows grazing ryegrass-white . clover pastures produced more milk and milk products at equivalent DM intakes than did cows grazing paspalum dominant pastures, and they were in better condition. This was due to herbage quality: cows grazing ryegrass-white clover pastures were able to select higher quality diets than could those grazing paspalum dominant pastures. When the results were compared with those from two previous stall-feeding experiments, the marginal efficiencies for milk production in all experiments were not significantly different; an extra 1.19 kg fat corrected milk was produced for each additional kilogram of digestible dry matter of pasture eaten. . The pastures were not grazed from May to September but their growth and quality were measured during this period. The amount of pasture left at drying off influenced the growth and quality of the pastures throughout winter: daily growth declined by 3.31 kg DM/ha between May and July, and by 6 56 kg DM/ha between July and September, as herbage yield at drying off (May) increased by each additional tonne of DM per hectare. Also, the ryegrass-white clover pastures grew more herbage at equivalent DM yields than did the paspalum dominant pastures. The implications of these results for grazing management are discussed.

Whole Sunflower Seed as a Fat Supplement for Lactating Cows

Complete rations containing whole sunflower seed at 0, 10, 20, and 30% of concentrates were fed to 16 Holstein cows during early lactation. All rations consisted of corn silage, alfalfa hay, and grain mixtures and were formulated to be isonitrogenous at 16% protein and nearly isocaloric at 1.50 Mcal net energy lactation per kilogram of dry matter. Intakes of total dry matter were not different among ration groups. Cows fed 10% sunflower seed produced more milk and were more efficient energetically. Treatment did not affect milk composition. Average secretion of shorter chain fatty acids in milk from caproate to palmitate was depressed, whereas oleate was increased by sunflower seed. Molar percentage of acetate was increased, and remaining variables measured in rumen fluid were not altered by dietary treatment. No health or feeding problems associated with whole sunflower seed supplement were observed during the entire trial. Graded increase of sunflower seed in the diet elevated cholesterol in blood serum with no effect on cholesterol in milk. Blood urea nitrogen remained unchanged, and total serum protein decreased with increasing sunflower seed in the diet.

Rumen Volatile Fatty Acid Production and Nutrient Utilization in Steers Fed a Diet Supplemented with Sodium Bicarbonate and Monensin

Effects of feeding dietary supplements of monensin and sodium bicarbonate singly or in combination on production of rumen volatile fatty acids, nitrogen balance, and rumen water kinetics were studied. Four rumen fistulated steers were fed a diet (50% concentrate mix and 50% corn silage) ad libitum in a 4×4 Latin square design (21-day periods) with a 2×2 factorial arrangement of treatments.Sodium bicarbonate increased feed intake, water intake, rumen pH, fluid dilution rate, and decreased both molar proportion and production rate of propionate in the rumen. Alteration of the ratio of acetate to propionate reflects the large decrease in propionate production relative to the small increase in acetate production. In contrast, monensin did not alter significantly rumen fluid dilution rate or ruminal pH but did decrease the molar proportion of acetate and increase that of propionate. Monensin increased production of both acetate and propionate in the rumen; however, the large increase in propionate production appears to account for more of the increase in molar proportion of propionate in the rumen. Increases in total volatile fatty acid production per kilogram of dry matter consumed with monensin supplementation appears to result from decrease in feed intake, thereby increasing ruminal retention time of dry matter and potentially the extent of digestion. Efficiency of nitrogen utilization was not altered by either sodium bicarbonate or monensin.

AN ESTIMATION OF THE VARIABILITY IN THE COMPOSITION OF ORTS FROM FEEDING TRIALS WITH LACTATING COWS

A total of 320 samples of feed refusals (orts) were obtained from 16 cows fed four different forage mixtures. These samples of orts were analyzed for dry matter, protein, acid detergent fiber and lignin. The observations on amount of orts expressed as kilograms of dry matter or percent of intake and the chemical composition of orts were statistically analyzed to determine differences between cows and rations. Regression analyses were run to determine the influence of amount of weighback on its chemical composition. Analyses of the data indicated that there were differences between rations in the degree of selection that cows exhibited for protein and for acid detergent fiber. These data indicated that there are substantial differences among cows in their ability to select components of a mixed silage ration. The results of this study demonstrated the need to obtain individual weighback samples for each cow on a feeding trial rather than obtaining a composite sample. It was suggested that the feeding of complete feeds to lactating cows may not necessarily result in a uniform consumption of nutrients.

Effects of concentrate type and leveland forage type on chewing time of steers.

Four double 3×3 latin square experiments were conducted to study the efforts of three concentrate-to-forage ratios (10:30, 40:60 and 70:90), three concentrate types and four forages, on chewing time of steers. Diets were fed for 14 days and chewing was monitored for the last 48 hours. Chewing time was reduced (P<.05) with each increase of concentrate level. Long hay and coarsely cut wheat silage resulted in more chewing time (P<.05) than finely cut sorghum or corn silage. Citrus pulp increased chewing time over ground corn or soybean mill feed. While there was some indication of interaction among forages and concentrate levels, mean values were linear, so we assumed the effect of concentrate and forage dry matter on chewing time was additive. Chewing time for the concentrate and forage was partitioned by regression. Roughage value index (chewing time per kilogram of dry matter) was 68.9 ± 3.2 SE for wheat silage, 67.3 ± 1.2 for corn silage, 59.7 ± 2.4 for sorghum silage, 78.5 ±5.5 for bermudagrass hay, 30.9 ± 15.4 for citrus pulp, 5.1 ± 4.2 for ground corn, and 8.4 ± 2.8 for soybean mill feed.

Nutritional Myopathy Due to Vitamin E Deficiency in Calves Fed Fish Protein Concentrate as the Sole Source of Protein

Thirty male Holstein calves 3 to 7 days of age were used in an initial experiment to compare four rations containing fish protein concentrate (FPC) as the sole source of protein with two rations containing dried skimmilk. Necropsy examination at the conclusion of 8 weeks revealed a greater incidence and severity of nutritional myopathy in FPC-fed calves than in milk-fed calves despite all diets were supplemented with 46mg vitamin E per kilogram of dry ration.A second experiment to determine optimal dietary tocopherol supplementation for calves on fish protein diets as compared to calves fed skimmilk diets used 19 8-day-old Holstein calves of both sexes. Clinical signs of illness such as weakness and diarrhea were common among calves fed a fish protein ration unsupplemented with vitamin E. Histopathologic examination of tissues from two calves from each of five groups revealed no myopathy in calves receiving fish protein or skimmilk rations containing 46 or 92mg DL α-tocopheryl acetate per kilogram of ration. Of those receiving no supplemental vitamin E, both calves on fish protein and one on skimmilk had myopathy.Calves fed skimmilk gained more weight than fish protein-fed calves. Vitamin E supplementation improved the growth rate of calves fed fish protein, and calves on fish protein rations containing 92mg DL α-tocopheryl acetate per kilogram of dry matter gained more weight than calves on such rations containing only 46mg per kilogram. Tocopheryl supplementation did not increase growth rates of skimmilk-fed calves. Plasma tocopherol of all calves declined during the experiment, but among calves receiving supplemental tocopheryl, declines were greater in fish protein-fed calves than in those fed skimmilk.