The effect of urea on the utilization of ground, pelleted roughage by penned sheep: II. Utilization of organic matter, nitrogen and minerals

Coombe, JB; Christian, K. R.

doi:10.1017/s0021859600022164

Cited by 8 publications

(5 citation statements)

References 25 publications

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“…1), but differences in Ca and Mg intakes may have also been involved. This lack of response is surprising because P intakes of unsupplemented sheep were well below recommended levels, and these sheep were always in negative P balance, as in a previous experiment (Coombe & Christian, 1969). However, serum inorganic P values generally remained within the limits recognized as normal (Dukes, 1955;Meier, 1963;Hemingway, 1967) and this was probably due to the influence of live-weight losses.…”

Section: Discussionmentioning

confidence: 76%

“…Based on the health, food intake and growth of animals, nutrient balances and, in some instances, blood levels, mineral requirements for ruminants in terms of dietary composition have been given as 0-1-0-15% S, 0-16-0-2% P, 0-15-0-32% Ca, 0-06-0-07% Mg, 0-35% K and 0-16-0-2% Na (National Research Council, 1964;Agricultural Research Council, 1965;Underwood, 1966;Hungate, 1966;Hemingway, 1967). Required actual daily intakes of minerals have been summarized by Coombe & Christian (1969). Since ruminants' requirements must meet the needs of the rumen micro-organisms as well as the tissues of the animal, some efforts have been made to establish minimum rumen requirements of various minerals.…”

Section: Discussionmentioning

confidence: 99%

“…Dried, clean wool samples were ground with liquid air, using a pestle and mortar to obtain a homogeneous sample for S determination. Preparation of samples of food, food residues, faeces and urine and their subsequent analysis have been described previously (Coombe & Christian, 1969;Coombe & Preston, 1969). Serum inorganic phosphate was estimated, after precipitation of serum proteins with 10% trichloroacetic acid, by the method of Briggs (1922).…”

Section: Methodsmentioning

confidence: 99%

“…During the second and third weeks of each period, four sheep from each treatment were placed in metabolism cages for digestibility and balance studies as described previously (Coombe & Christian, 1969). Dilute acetic acid (1:1, v/v) was used to AGS77 maintain acid conditions in the urine containers, and 5 ml 10% (w/v) cupric chloride (CuCLj.2H 2 O) solution daily were also included as a urine preservative.…”

Section: Digestibility and Balance Studiesmentioning

confidence: 99%

“…Low-quality roughages are generally deficient not only in N but also in other elements, particularly sulphur and phosphorus, and it is possible that the value of protein supplements is partly due to their content of nutrients other than N. In a previous experiment described by Coombe & Preston (1969), sheep fed ground, low-quality roughage supplemented with urea showed marked improvements in food intake, live-weight performance and wool growth following a change from a commercial to a laboratory-prepared mineral mixture, while sheep fed the same roughage without urea showed no such response. Retention data indicated that a substantial improvement in the utilization of urea-nitrogen had occurred, and it was suggested that this was most likely due to an improvement in mineral status (Coombe & Christian, 1969). This paper describes an experiment designed to establish which supplementary minerals are important, and to determine the increase in animal productivity which may be expected from their use.…”

Section: Introductionmentioning

confidence: 99%

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The effect of urea on the utilization of ground, pelleted roughage by penned sheep: III. Mineral supplements

Coombe¹,

Christian²,

Holgate

1971

J. Agric. Sci.

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Seven, groups of adult Merino wethers were fed for 16 weeks on a diet of pelleted oat straw and urea, either alone or supplemented with trace minerals and various combinations of the major minerals. In some treatments, the same diet was fed throughout; in others, diets were changed after 8 weeks.Sulphur (S) was by far the most important mineral supplement; sheep fed diets supplemented with all minerals except S performed as poorly as those on the basal diet. Of the other minerals, only calcium (Ca) and magnesium (Mg), which were fed in combination, had a small, additional beneficial effect. Supplementary phosphorus (P) had no effect whether or not S was included.Intakes of sheep on S-supplemented diets increased over the first 6 weeks to reach stable levels of 1200-1400 g D.M./day compared with approximately 800 g/day for controls, while O.M. digestibilities stabilized at about 40 and 33 % for S-supplemented and unsupplemented diets respectively. Live-weight change and wool growth were closely related to intake. Mean live-weight losses during the first and second 8 weeks for sheep without supplementary S were 9-5 and 4-8 kg respectively, and were about 50 % of this for supplemented sheep. Sheep which were changed from diets without supplementary S to S-supplemented diets after 8 weeks showed slight increases in live weight from then on. Wool growth was about 115 g clean wool/sheep on all treatments during the first month, after which it remained steady at about 105 g/month on S-supplemented diets and fell to 60 g/month on diets without supplementary S.Sheep without supplementary S were in negative nitrogen (N) and S balance throughout. With the S-supplemented diets, urinary excretion of N and S was high, and few positive balances were recorded until the final 4 weeks of the experiment. Serum urea levels were high (60-130 mg/100 ml) throughout, and showed no effect of diet or period. Phosphorus balances were uniformly negative in sheep without supplementary P, and generally positive in P-supplemented sheep. Serum inorganic P levels were apparently affected by P intake and by live-weight loss, but mean values never fell below 4-5 mg/100 ml.Sheep without supplementary Ca were in negative Ca balance throughout the experiment; however, Ca supplementation generally resulted in high faecal Ca losses and few positive balances were recorded. In some sheep, serum Ca fell to moderately low levels (7-5 mg/100 ml), but this appeared to be associated more with high serum inorganic P levels than low Ca intake or retention. All sheep were practically in Mg, Na and K balance throughout, and supplementation had little effect on the retention of these elements.All sheep were in very poor condition at the end of the experiment, even when their D.M. intakes had been high, and wool growth rates were mediocre throughout. It appears that urea was poorly utilized in this experiment, and that satisfactory sheep production on diets of ground straw supplemented only with urea and minerals is unlikely.

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Section: Discussionmentioning

confidence: 76%

Section: Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Digestibility and Balance Studiesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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The effect of urea on the utilization of ground, pelleted roughage by penned sheep: III. Mineral supplements

Coombe¹,

Christian²,

Holgate

1971

J. Agric. Sci.

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Utilization of nutrients by the dairy cow and optimal N:energy ratio in the diet

Paquay¹,

Godeau²,

Baere³

et al. 1973

Journal of Dairy Research

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The dietary and individual animal factors influencing the utilization of digestible nitrogen and of metabolizable energy for milk production were studied and change in. the optimal nitrogen:energy ratio during lactation was investigated using 35 different experimental diets and the individual results obtained from 119 Friesian cows whose daily milk production varied from 4 to 30 kg.The amount of N secreted in the milk and the daily milk production depended above all on the metabolizable energy intake and on the stage of lactation. They were related to the dietary N: energy ratio.The percentages of digestible N and of metabolizable energy utilized for milk production were also related to the dietary digestible N: metabolizable energy ratio of the diet.The optimal digestible N:metabolizable energy ratio ranged from about 2-2 g/MJ during the first 3 months of lactation to about 1-7 g/MJ in the sixth and seventh months and 1-3 g/MJ from the tenth month. When expressed in g N intake per MJ energy intake, this optimal ratio ranged from 1-6 after calving to 1-1 at the end of lactation.In the ruminant, close relationships exist between N metabolism and that of other dietary constituents.In a previous paper (Paquay, De Baere & Lousse, 1972a), the factors which influence the digestibility of N in the cow were studied. The results obtained for dry cows and lactating cows were studied together, since it was observed that the production of milk did not modify the digestibility of ration constituents. In agreement with other authors (Elliott & Topps, 1963a;Van Niekerk, Smith & Oosthuysen, 1967), it was found that N digestibility is strongly related to the crude-protein content of the diet, and the amounts of digestible N are determined by the N intake level and also by the dry-matter intake level.On the contrary, when studying the utilization of digestible N, it is necessary to consider separately the values obtained for dry cows and lactating cows, since the production of milk largely modifies the fate of dietary N and the interactions between the dietary constituents. The influences of dietary and individual animal factors on N utilization in the dry cow were studied previously (Paquay, De Baere & Lousse, 19726).

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Intake and digestion of mature Flinders grass (Iseilema spp.) by sheep and their response to the addition of urea and minerals

Stephenson¹,

Weston²,

Margan³

et al. 1983

Aust. J. Agric. Res.

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Studies were conducted of the voluntary feed consumption (VFC) and digestion by sheep offered mature Flinders grass hay containing, on a dry matter basis, 4.2% crude protein (CP), 71.8% cell wall constituents (CWC) and 12.6% total ash. The nutritive value of the hay was low, as indicated by the relatively low values for organic matter (OM) digestibility (40.9%), VFC (879 g OM/day) and CP digested in the intestines (5.8 g CP/100g feed OM intake). Digesta flows from the rumen and abomasum per unit OM intake, rumen and abomasal digesta pH, ammonia concentration in rumen liqour, and CP reaching the intestines relative to CP and digestible OM intakes were similar to values previously obtained with temperate grasses. Supplementation of the hay with urea increased VFC by 16%, and minerals in addition to the urea enhanced it by a further 6%. The supplements substantially increased OM and CWC digestibilities (by 16-17%) and CP digested in the intestines (DCPi) per unit hay intake (by 10%); these improvements could be attributed to changes in ruminal digestion. The higher levels of intake and digestion with the supplements were accompanied by increased concentrations of volatile fatty acids (VFA) in the rumen. It was calculated, by using the ad libitum feeding results, that the supplements of urea and minerals would have increased the intakes of digestible OM and DCPi by 44 and 36% respectively. However, with the supplements, DCPi per kg digestible OM remained low at 13.3 g. The data facilitate interpretation of previous animal production studies with Flinders grass hay and indicate that production may be limited by inadequate amino acids in the supplemented diet.

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The effect of urea on the utilization of ground, pelleted roughage by penned sheep: II. Utilization of organic matter, nitrogen and minerals

Cited by 8 publications

References 25 publications

The effect of urea on the utilization of ground, pelleted roughage by penned sheep: III. Mineral supplements

The effect of urea on the utilization of ground, pelleted roughage by penned sheep: III. Mineral supplements

Utilization of nutrients by the dairy cow and optimal N:energy ratio in the diet

Intake and digestion of mature Flinders grass (Iseilema spp.) by sheep and their response to the addition of urea and minerals

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