Rumen Ammonia Levels Research Articles

COMPARATIVE VALUE OF SOYBEAN, RAPESEED, AND FORMALDEHYDE-TREATED RAPESEED MEALS IN UREA-CONTAINING CALF RATIONS

Twenty-four Holstein calves were fed three experimental rations containing either 14% soybean meal, 20% rapeseed meal, or 20% formaldehyde-treated (0.7 g formaldehyde/100 g protein) rapeseed meal from 8 to 22 wk of age. No significant differences (P > 0.05) were observed in feed consumption, dry matter intake, liveweight gain, and feed conversion among the three groups. There was a significant (P < 0.05) reduction in rumen ammonia levels in calves receiving the treated rapeseed meal compared with the untreated rapeseed meal rations. Plasma urea levels and rumen fluid volatile fatty acids (mmol/100 ml and molar percent) did not differ significantly (P > 0.05) among treatments. There were no significant differences in the digestibilities of dry matter, nitrogen, acid detergent fiber, and gross energy among treatments, although treating the rapeseed meal with formaldehyde tended to reduce dry matter, nitrogen, fiber, and energy digestibility.

The performance of calves given concentrate diets treated with formaldehyde

Five groups of Friesian bull calves were given concentrate diets containing 70 % barley in which low (12 %), medium (15 %), and high (19%) protein levels were obtained by varying the amount of peanut meal included. The effects of protein level and of formaldehyde treatment of the complete diet at the low and medium protein levels were studied in terms of liveweight gain, voluntary food consumption, digestibility of the diet, ammonia nitrogen in rumen fluid, and urea and a-amino nitrogen in blood plasma. Observations were begun when the calves reached 70 kg liveweight and continued until they reached 130 kg liveweight. The calves given the low protein diets grew more slowly than those given the higher protein diets. The calves given the high protein diet grew no better than those given the medium protein diets. Formaldehyde treatment was associated with an increase in the rate of liveweight gain of 9% (P = 0.11) at the low protein level but had practically no effect at the medium protein level. The treatment did not adversely affect voluntary food consumption but was associated with decreases in the digestibility of nitrogen and in rumen ammonia levels and small increases in plasma urea levels.

Digestion of two legumes and rumen bacterial growth in defaunated sheep

Defaunated sheep offered lucerne hay or dried red clover were used to study digestion in the stomach of dietary organic matter, plant cell wall constituents, and plant cell contents. Digestion in that section of the tract was, for dietary organic matter, 50 % with lucerne and 60% with red clover, for plant cell contents 65–70% with both diets, and for plant cell wall constituents 30% with lucerne and 60 % with red clover. Estimates of growth of rumen bacteria in these sheep indicated that about 32 g of bacterial organic matter and 23 g of bacterial crude protein were synthesized in the rumen for each 100 g of plant organic matter digested. Comparisons of apparent digestion in the stomach and intestines were made between the defaunated sheep and the same sheep carrying a normal population of rumen microorganisms. Levels of rumen ammonia were lower in the absence of protozoa. However, only small differences were observed in the flow of digesta along the tract and in the apparent digestion of organic matter and nitrogen in both the stomach and intestines as a result of defamation. Hence it is suggested that data on the digestion of forages obtained with defaunated sheep can be applied to sheep with rumen protozoa.

SOME EFFECTS OF RUMINAL INFUSIONS OF UREA AND UREA-SUCROSE ON UTILIZATION OF OAT STRAW BY COWS

Four diets, straw, straw plus urea, straw plus urea and sucrose, and straw plus urea but with a different mineral supplement than fed with diets 1 to 3, were compared using rumen-fistulated cows. Urea or urea and sucrose were dissolved in water and administered as continuous ruminal infusions. Increases of about 29% in dry matter digestibility and 17% cellulose digestibility were obtained with urea but not with urea-sucrose. Bacterial protein in rumen fluid was increased by an average of 63% by both urea and urea-sucrose treatments. Rumen ammonia and blood urea levels were increased tenfold and threefold, respectively, by the urea infusion, but the response to urea-sucrose was only one-half as great. Sucrose appeared to be used as an energy source in preference to the straw, as indicated by the increased rate of urea utilization, but tended to depress intake and digestibility of straw as compared with urea only. Dry matter intake, nitrogen balance and total short-chain fatty acids were not significantly altered by the treatments, but all snowed response trends. Effects of dietary treatments on proportions of short-chain fatty acids in the rumen were not consistent.

The effect of Water Loading on urea metablism in Cattle

SUMMARYSteers fed low nitrogen diets were infused intraruininally with water.Increasing the water load increased the urine volume and urinary urea excretion and depressed the plasma urea level.The effect of intraruminal water loading was studied in association with intravenous urea loading of 25 and 65 g N/day. When 25 g N/day as urea was infused intravenously, water loading did not significantly increase the urinary urea excretion but the plasma urea level was depressed. At 65 g N/day water loading increased the urinary urea excretion and decreased the plasma urea level.Significantly different relations between plasma urea and urea load existed for the ad lib. water and the water-loaded treatments but the relation between rumen ammonia level and plasma urea level was not affected by the water loading.The results are discussed with reference to the recycling of urea.

Relationship Between Rumen Ammonia Levels and the Microbial Population and Volatile Fatty Acid Proportions in Faunated and Defaunated Sheep

Cheviot wethers were defaunated by using dioctyl sodium sulfosuccinate and were constantly infused with urea to provide 2.87% of the daily N intake. Defaunation resulted in higher rumen dry matter and lower rumen p H. The molar per cent propionate was higher in defaunated sheep, whereas the molar per cent butyrate and acetate was lower. Apparent nitrogen digestibility, nitrogen utilization, and nitrogen balance were higher in defaunated sheep when compared with faunated animals. Urea infusion resulted in lower apparent nitrogen digestibility, nitrogen utilization, and nitrogen balance in faunated sheep, but did not affect nitrogen metabolism in defaunated sheep. Rumen ammonia-N levels in defaunated sheep were lower than those observed for faunated animals, and urea infusion into faunated sheep increased rumen ammonia-N levels to a greater extent than did the urea infusion into defaunated animals. Significant correlations were demonstrated between rumen ammonia-N levels and C 2 /C 3 , C 3 /C 4 and C 2 /C 4 volatile acid ratios. From this it was concluded that, as rumen ammonia-N levels increased, there was a shift from propionate to higher proportions of butyrate and acetate.

The effects of increased nitrogen intakes on plasma urea nitrogen and rumen ammonia levels in sheep

A series of five roughage rations providing increasing amounts of nitrogen (6.8, 16.8, 23.5, 37.3, and 46.3 g/day) and some changes in dry matter intakes (720, 710, 704, 1056, and 1408 g/day) was offered to sheep. The first four rations were given hourly and the fifth ad libitum. Urine outputs, urine total nitrogen, urine urea nitrogen, and urea clearance values increased with nitrogen intakes. Water intakes were linearly related to dry matter intakes. Plasma urea nitrogen and rumen ammonia levels both increased linearly to about 30 mg/100 ml, but did not increase further on higher levels of nitrogen intake. At these levels of intake both plasma urea nitrogen and rumen ammonia levels were no longer related to urine nitrogen excretion rates. The results are discussed in relation to the role of the kidney tubules in nitrogen excretion in the sheep.

Relationship Between Rumen Ammonia Levels and the Microbial Population and Volatile Fatty Acid Proportions in Faunated and Defaunated Sheep 1

Cheviot wethers were defaunated by using dioctyl sodium sulfosuccinate and were constantly infused with urea to provide 2.87% of the daily N intake. Defaunation resulted in higher rumen dry matter and lower rumen pH. The molar per cent propionate was higher in defaunated sheep, whereas the molar per cent butyrate and acetate was lower. Apparent nitrogen digestibility, nitrogen utilization, and nitrogen balance were higher in defaunated sheep when compared with faunated animals. Urea infusion resulted in lower apparent nitrogen digestibility, nitrogen utilization, and nitrogen balance in faunated sheep, but did not affect nitrogen metabolism in defaunated sheep. Rumen ammonia-N levels in defaunated sheep were lower than those observed for faunated animals, and urea infusion into faunated sheep increased rumen ammonia-N levels to a greater extent than did the urea infusion into defaunated animals. Significant correlations were demonstrated between rumen ammonia-N levels and C(2)/C(3), C(3)/C(4) and C(2)/C(4) volatile acid ratios. From this it was concluded that, as rumen ammonia-N levels increased, there was a shift from propionate to higher proportions of butyrate and acetate.

The effects of intravenous urea infusions on nitrogen metabolism in sheep

The effects of intravenous infusions of measured amounts of urea solution into sheep, providing c. 5 g urea nitrogen per day, were studied in sheep on four rations differing in crude protein and readily available energy content. Nitrogen balances, water intakes, urea nitrogen excretions, and diurnal variations in plasma urea and rumen ammonia levels were compared over 8-day collection periods. When corn starch and dried molasses provided readily available energy in addition to crushed pure cellulose the retention of infused urea nitrogen was 50 % compared with 40 % with crushed pure cellulose. It is suggested that as nitrogen retention was similar to the increases in nitrogen balance, the nitrogen retained was first transported into the rumen, where it was synthesized to microbial protein. Thus corn starch, molasses, and crushed cellulose provided suitable energy levels for utilization of the extra nitrogen by the rumen micro-organisms. On a low protein, all roughage ration the nitrogen transferred into the rumen produced increased rumen ammonia levels and was subsequently reabsorbed and excreted in the urine.

Effect of Supplementing Predominantly Roughage Rations with Oats Grass, Trace Minerals, or B-Vitamins on Nutrient Utilization1,2

Twenty-four wethers were utilized in a 2×2×2 factorial experiment with three replicates, to determine the effects of trace minerals, B-vitamins, and hydroponically produced oats grass on a high-roughage diet. Addition of oats grass had no effect on the digestibilities of any nutrients. When trace minerals were added to the ration, the digestion coefficient for nitrogen-free extract was increased significantly (P<.05). Trace minerals depressed the digestibility of ether extract (P<.05).Addition of oats grass resulted in a narrowing of the acetate-to-propionate ratio (P<.01), decreased the amount of acetate (P<.01), and increased the amount of propionate (P<.01) and butyrate (P<.01).Blood ammonia and urea levels were not affected significantly when oats grass was present. Similarly, addition of trace minerals and B-vitamins plus vitamin E had no effect on the rumen ammonia levels or rumen pH.

The effect of antibiotics on ammonia accumulation and protein digestion in the rumen

A study was made of the feasibility of using antibiotics to reduce ruminal deamination of protein that comprised 27% of the organic matter in a diet of lucerne hay and casein. Six sheep were each dosed with a different antibiotic. At the levels given, penicillin and erythromycin reduced rumen ammonia levels by about 35%, but also reduced food intake. Chloramphenicol reduced rumen ammonia by about 50% but neomycin, oxytetracyclene, and streptomycin had little effect.When all six sheep were subsequently dosed with chloramphenicol at 1 g/day the levels of rumen ammonia were reduced only to 85% of the control. The antibiotic had little effect on the extent of digestion of protein, organic matter, and cellulose, both in the stomach and in the whole alimentary tract, and on parameters associated with the movement of digesta through the stomach The quantity of nitrogen passing from the stomach in forms other than ammonia was 52–54% of intake during both the control and treatment periods. Much of this nitrogen probably passed from the stomach in the form of microbial protein, which indicated that the dietary protein was extensively digested. In consequence of the loss of nitrogen from the stomach, the protein apparently digested in the intestines was equivalent to only about 14.5 g/100 g digestible organic matter.

The nutrition of the early-weaned calf. X. The effect of replacement of fish meal with either urea or ammonium acetate on growth rate and nitrogen retention in calves fed ad libitum

1. A growth trial and nitrogen balance studies were carried out on 32 early-weaned calves fed on a basal diet containing fish meal or diets in which the fish meal nitrogen was partially replaced by urea or ammonium acetate or totally replaced by urea.2. Growth rate and feed conversion efficiency were highest on the fish meal diet and fell as urea replaced the fish meal.3. Rumen ammonia levels and urinary nitrogen excretion were highest, and nitrogen retention lowest, in the calves receiving the diet in which fish meal nitrogen was completely replaced by urea nitrogen.

The functional development of the calf II. Development of rumen function in the calf

1. Two experiments were conducted to study the development of rumen function in young dairy calves under different feeding regimes.2. The volume of the rumen contents increased with age whereas the volume of the abomasum contents tended to remain constant.3. The concentration of total volatile fatty acids in the rumen liquor of milk-fed calves with free access to pasture reached constant levels at 5 weeks of age. Restricting calves to an all milk diet delayed the development of adult levels of volatile fatty acids until such time as roughage became available.4. Levels of rumen ammonia were high soon after birth but showed a decline with age. An absence of roughage in the diet tended to maintain higher levels of rumen ammonia.5. The pH of rumen liquor showed a steady increase from birth to 17 weeks of age.6. Both volatile fatty acid and ammonia levels in the rumen showed a characteristic diurnal pattern of variation.7. High figures for the digestibility of pasture by young calves were obtained. When calves which had been restricted to an all milk diet were offered roughage they quickly attained a digestive efficiency comparable with calves which had access to pasture from birth.