2.1 The Nitrogenous Constituents of Fresh Forages

1982 ◽  
Vol 6 ◽  
pp. 25-40 ◽  
Author(s):  
J. L. Mangan

The nitrogenous composition of forage is largely determined by the requirements of plant physiology, with variables such as anatomy, e.g. monocotyledons v. dicotyledons, maturity, fertilizer treatment, climate, light intensity, etc., superimposed. One would therefore expect to find many broad similarities in the composition of plants. Chibnall (1939) recognized this and gave a comprehensive review of early work on metabolism and nitrogenous composition of leaves. Present systems for the assessment of protein requirements of ruminants (e.g. Agricultural Research Council, 1980) require a detailed knowledge of the composition of feedstuffs in terms of rumen degradable and undegradable proteins and of non-protein nitrogenous compounds utilized by rumen microorganisms. It is also apparent that the biological value of protein which bypasses the rumen should be determined. Descriptions in terms of “crude protein” (Kjeldahl N × 6.25) are no longer adequate. The proteins of fresh forages may be considered in 3 main groupings (1) Fraction I leaf protein (2) Fraction 2 proteins and (3) Chloroplast membrane proteins.

1978 ◽  
Vol 91 (2) ◽  
pp. 483-486 ◽  
Author(s):  
E. R. Ørskov ◽  
D. A. Grubb

SUMMARYMilled barley straw, either untreated or treated with 70 g of NaOH/kg straw was supplemented with four levels of urea, namely 0, 6, 12 or 18 g/kg and fed ad libitum to young sheep. For the untreated straw, dry-matter intakes were (g/day) 423, 451, 441 and 463, while the digestibility of organic matter was 458, 467, 490 and 483 g/kg, respectively. For the treated straw, the intakes of dry matter were 355, 402, 531 and 567 g/day and the digestibility of organic matter was 423, 480, 589 and 628 g/kg respectively.The different responses to urea supplementation of treated and untreated straw are discussed in relation to a new system of estimating protein requirements for ruminants put forward by the Agricultural Research Council.


1970 ◽  
Vol 75 (1) ◽  
pp. 11-18 ◽  
Author(s):  
R. P. Andrews ◽  
E. R. Ørskov

SUMMARYThe live-weight gains of male and female lambs were measured during growth from 16 to 40 kg live weight when five cereal-based diets varying in dietary crude protein concentration (from 10 to 20%) were given at three levels in a 5×3×2 factorial design.Males grew faster than females by about 15% (P < 0·001); this difference increased with age and with the amount of feed given (P < 0·05). Growth rate responded linearly to increase in feeding level (P < 0·001) and curvilinearly to increase in dietary protein concentration (P < 0·01). A significant interaction (P < 0·01) occurred whereby growth increased with higher protein concentrations as feeding level increased.At the highest feeding level (near ad libitum) the results suggest that the optimum dietary crude protein concentration for growth was about 17·5, 15·0, 12·5 and 12·5% at body weights of 20, 25, 30 and 35 kg respectively. The overall optimum dietary crude protein concentration for growth between 16 and 40 kg body weight was about 17·0, 15·0 and 11·0% when the mean digestible energy intake was 3·0, 2·6 and 2·1 Mcal/day.The results agree reasonably well with estimates of protein requirements for lambs given by the Agricultural Research Council (1965).


2009 ◽  
Vol 33 (6) ◽  
pp. 1637-1642 ◽  
Author(s):  
Rodrigo Palomo de Oliveira ◽  
Juan Rámon Olalquiaga Perez ◽  
Joel Augusto Muniz ◽  
Antonio Ricardo Evangelista ◽  
José Camisão de Souza ◽  
...  

The experiment was carried out in the sheep division of Universidade Federal de Lavras, aiming to evaluate the effect of different concentrate : voluminous ratio on the performance of Santa Inês lamb after wean. 40 lambs, male uncastrated, were used and fed with four different diets: diet A (100% concentrate), diet B (75:25 concentrate : voluminous) , diet C (50:50 concentrate : voluminous) , diet D (25:75 concentrate : voluminous). The experimental diets were isoproteic, differing only on its levels of concentrate : voluminous and balanced to meet the nutritional demands according to the recommendation of the Agricultural Research Council (1980). The experimental period was not pre-established, because it corresponded to the necessary period for the last lamb to reach the live weight of 35kg. The dry matter consumption (DMC), crude protein consumption (CPC), fiber in neutral detergent consumption (FNDC) and fiber in acid detergent consumption (FADC), were affected by the different concentrate : voluminous ratio, in which, the animals that received diets with higher concentrate inclusion presenting better results for the variables related to the development. The lambs fed with the diet containing higher inclusion of voluminous did not present weight gain, on the contrary, presented weight loss, since none of the animals reached slaughter weight and the mortality rate was extremely high (80%).


1982 ◽  
Vol 6 ◽  
pp. 99-106
Author(s):  
R. H. Smith

The system put forward by a working party of the Agricultural Research Council is fully described in a recent publication (ARC, 1980) and will be outlined only briefly here. Most attention will be given to considering the usefulness of the system, some of its limitations and probable ways of future development.It is proposed in the scheme that a diet should be formulated in terms of metabolizable energy needed for the required performance. This energy intake largely determines the maximum amount of microbial growth possible in the rumen per day and therefore the amount of N that has to be made available to the microorganisms to achieve this growth. This is referred to as the rumen degradable nitrogen (RDN) in the diet (the crude protein equivalent (RDP) = RDN x 6.25) and its utilization forms the first in a chain of events relating the N compounds eaten with the compounds deposited in the animal's body or products. All the events in the chain are affected by a variety of factors and some of these will be discussed later but, in order to demonstrate the principle of the scheme, average values derived from the literature and given in ARC (1980) will be assigned to them.


1985 ◽  
Vol 25 (2) ◽  
pp. 257 ◽  
Author(s):  
DJ Barker ◽  
PJ May ◽  
PER Ridley

Weaner steers were fed to attain either fat score 1 or 2 by the time that they were 1 year of age. Animals at each fat score were then either slaughtered or fed ad libitum on a basal barley and hay diet containing 11% crude protein or similar diets supplemented by either urea, meat meal or sweet lupins to contain 13% crude protein in the dry matter. Those fed were slaughtered as they attained fat score 3. Compared with those starting at fat score 2, the yearlings at fat score 1 had the same daily feed intake and thus a 10% higher relative intake, grew 15% faster and required 11% less feed per kg liveweight gain. However, they required only 6% less feed per kg carcass weight gain, owing to their 1% lower dressing percentage. The diets supplemented with the three different sources of supplementary nitrogen gave similar improvements over the basal diet in intake, growth rate and efficiency, and there were no interactions between diet and fat score. It was concluded that both the National Research Council and Agricultural Research Council feeding standards underestimate the nitrogen concentration required in grain and hay diets to ensure maximum performance and efficiency by yearling cattle growing from 220 to 370 kg liveweight, and that supplements of either urea, meat meal or lupins providing an extra 2 percentage units of crude protein improve performance to a similar extent.


1951 ◽  
Vol 64 (3) ◽  
pp. 257-276
Author(s):  
D. P. Cuthbertson

The Rowett Institute for research on animal nutrition had its origin under a scheme for promoting scientific research in agriculture adopted by the Development Commission in 1911.The Governing Body, which originally consisted of an equal number of members appointed by the Court of the University of Aberdeen and the Governors of the North of Scotland College of Agriculture, was constituted in 1913. Within recent years it has been expanded to include persons nominated by the Secretary of State for Scotland, the Royal Society, the Royal Society of Edinburgh, the Agricultural Research Council, and the Medical Research Council. Research work was begun in temporary accommodation in Marischal College in 1914, under the direction of Dr John Boyd Orr—now Lord Boyd-Orr—who continued as Director until his retirement in 1945.


1984 ◽  
Vol 102 (1) ◽  
pp. 135-139 ◽  
Author(s):  
G. D. Braithwaite

SummaryThe effect on phosphorus and calcium metabolism of a high rate of Ca infused directly into the blood of 10-month-old sheep, already receiving an adequate Ca and P intake, has been studied by a combination of balance and radioisotope techniques. Ca retention was significantly increased during the infusion and most of the extra Ca was retained in bone. Urinary Ca excretion also showed a small but significant increase and the efficiency of Ca absorption a small but significant decrease. Because of the close association of Ca and P in bone, the increased skeletal retention of Ca resulted in an increased skeletal P retention and hence an increased demand for P. This increased P demand was met partly by a decrease in the rate of endogenous faecal loss of P and partly by an increase in the rate and efficiency of P absorption. Because the increase in P demand was relatively small, it was not possible to decide whether the endogenous faecal loss of P can be reduced in response to increased demands to the level found at zero P intake as suggested by the Agricultural Research Council (1980) or whether higher losses at normal P intakes are inevitable.


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